![G]A Iation of T E Puo·Et Ound R O·· N](http://data.docslib.org/img/ee91da8b655eb6112cd528c647df3c3d-1.webp)
L ------HENRY LANDE , tate ol "'I t
G]a iation of t e Puo·et ound R o·· n
B J. RE
OLY ll'IA, WA.SH,; l'lliNK .i. l:.illJIO&N l'UBLIC rnu,na 1918
B ARD O G •O VEY.
Governor Ex~rasT L TEll, ltairman.
i utcnant Gonrnor Lo F. fuRT. tate Tre ur r EDWARD 11 ! e TH, ecretary. Pr ident T. F. KAlra. Pr ident E. A. Ba.YAN.
HE '11Y LA1.'l>ES, tatc G ologiat.
o Cf I 7 LETTER OF TRANSMITTAL.
Governor Ernost Lister Chairmam, and Members of the Board of Geological Swrvey: GEN'l'LEMEN: I have the honor to submit herewith a. report entitled "Glaciation of the Puaet ound Region,' by J. Har len Bretz, with the recommendation that it be printed as Bul letin No. 8 of the Survey reports. The surface deposits about Puget ound, as shown in the ea-cliff C..'{cavation for street , tunnels and elsewhere have always attracted much attention. They a.re of economic im portance, not alone from an agricultural standpoint but be cau e of the valuable bed of clay and and gravel which they contain. Local chapters in the tory of tbe glaciation of Puget Sound have been contributed by dHferent writers at different time but thi bulletin by Mr. Bretz i the first de tailed account covering all pha es of an interesting portion of the geological history of tl1e region. This 1·eport by Mr. Bretz ha .involved several year of field-work and study, the expen es of which were ustain.ed by him personally, except that a small allowance toward the co t of the field-work was granted him by the ur ey during the ummer of 1911. Very re pectt'ully, HENRY LANDES, State Geologist. University tation Seattle May I, 1918. TABLE O CO -rTE TS.
Paue [NTRODUCTION 9
CHAPTER I. 00TLIN'E OF T1IE PLEI TOOEN'E HI TORY OF THE REGJO • . . . • . • . . .• • . • . • .• • . • . • . • . • •• • • . • • • • 13
OHA.PTER JI. THE TEllli:INAL MORAINE OF PUGET Sou::..'D...... 23
CHAPTER III. EXTJU· foRAlliIO 0tJTWAS:S: OF TRE PCGET Somm RrotON • • . . • • • . • •• • • . • • • • . • . • • • . . • • . • • • • • . . 38
CHAPTER IV. VASHON REcEB roNA.L Mon, TN£ ANO ATTENDANT OtJTWASR • • • • • . • • . . • . • . . . . • • . • . • . . • • • • • . • • • 61
CHAPTER V. THE Momws OF THE V AfillON OUTWASII. • • • • . . . • 81
CHAPTER VI. Tm;; GLAOIA.L L.uo.:s A 'D DRA!NAOE CHANGES OF nu: VASHO!', GLACIAT.JON ••.•••...••••••.•••. , 109 CHAPTER vrr. TRE ADAmw::rY GUC!ATION •..•....•...... 173
CHAPTER VIII. 0RIGUI" OF TRE TnOUGRB Oli PuGET SOUND ••••.••• 195 CHAPTER IX. R.Er.ATJONS OF GLACTATJON Ol" TUE FU.NKINO MOUNTAINS TO TIIAT OF TRE PUGEl' SOUND BA.SIN ...... 221
CHAPTER X. Pu:t TOOE,·E AND Po T-Pu:tS'l!OCENS DIASTROPJIIBM 226
WASH!~ G STATE L1BRAR ILLU TR.A.TIO Facing Plate Page I ...... 40 Fig. 1. The Satsop Red Gravel Terrace. 2. Surface o·f Satsop Red Gravel Terrace. 3. Section of Red Gravel tn Satsop Terrace. IT ...... 48 Flg. 1. Mound Section i.n N. P. R. R. Plt, Mlma Prairie. 2. Mound Topography on Muna Prairie. Ill ...... 56 Fig. 1. Large Intermound Area on .Mima Prairie. 2. Typical Mounds on Mjma Prairie. IV ...... 64 Fig. 1. Mounds on the orthern Portion of Mima Prairie. 2. Kettle Among Mounds, Mirna Prair1e. V ...... 72 Fig. 1. Rocky Prairie Mounds with Intermound Cobbles. 2. Rocky Prairie Mound . VI ...... 80 Fig. 1. Mounds of Rocky Prairie. 2. Mounds of Rocky Prairie. VII 88 Fig.1. Delta at Corner Seneca St. and Sixth Ave., Seattle. 2. Mounds cut by Highway, Muna Prairie.. VIII. An rea of Typical Mounds on Mlrua Prairie...... 96 IX 104 Fig. 1. Ford Type Mound on Grand Mound Prairie. 2. Bedding of Mirna Prairie Outwash. Gravel. X ...... 112 Fig. 1. Prairie Oalc, killed by Invading Fir Forest. 2. Upper Falls of the Des Chutes River. XI 120 Flg. 1. Section in the Steilacoom Delta. 2. Section in the Richmond Delta. xn 152 Flg.1. Distorted Admiralty Sediments, McNeil's Island. 2. Structure of lbe Quatsap Point Delta Beds. Illustrations 7
Facing Plate Page XJTI. Cole Point, Anderson Island...... 160 xrv. Denny Hill Regrade ...... 176 xv . , ...... •...... 184. Fig. 1. Old River Channel above Kennydale Delta. 2. Percival Creek Channel. 3. "Spite Hlil" of Denny Hill Regrade. XVI 192 FJg. 1. Portion of Denny Hill Regrade, Sea tle. 2. The Grade on Bell SLreet, Denoy HUJ Regrade, Se attle. xvn. Crumpled Olay Stratum of Camano Island...... 200 XVIII 208 Fig. 1. Vashon Till Sea curr at Tip of Cape Horn. 2. Drumllnoid Forms or Vashon TW on Fox Island. XIX 216 Fig. 1. Vashon Till Sea Clltt, Brisco Point. South End ot Hartstene Island. 2. Vaahon TIU on Marrowstone Island, AdmJralty Inlet. XX ...... •...... •...... 224" Fig. 1. Drowned alley of Chambers' Creek at Low Tide. 2. Cattle Poln1. Hill, San. Juan Island. XXI 232 Fig. 1. Sea Cliff in South R111, San Juan I land. 2. Erratic on Vashon Ground Moraine, near Port Gam· ble. XXTI. Pleistocene Surface Deposits of Puget Sound Basin .. ln Pocket XXIII. Moraine and Outwasb South of Puget Sound ...... In l'ocket XXIV. Bathymetrlc Map of Puget Sound ...... •. In Pocket 8 Illustrations li'iqure. Page 1. Profl.le of the Vashon TennJnal Moraine...... 36 2. Glacial Drainage from Eastern Lobe ot Puget Sound Glacler, at its .Maximum Elxtent...... 44 3. Glacial Drainage from Eastern Lobe of Puget Sound Glacler, during building of Mima and Tenalquat PralrJes ...... ,... 55 4. Glacial Drainage from Eastern Lobe o! Puget Sound Glacier, during bu.ilcling of Rocky Prairie...... 63 5. Diagrammatic Cross Section of Tenalquat Prairie...... 65 6. Glacial Drainage, etc., during building of Yelm Prairie...... 70 7. Time and Space Relations of the Glacial La.lees durlng Vashon Retreat ...... ll.1 8. Lak Puyallup and Elru:Jy Lake Russell ...... 124 9. A _portion of the City of Tacoma, showing Location of the Tacoma Delta, the Various Pits in it, the South Tacoma Channel Head, and Position of Ice Front at Time ot Delta Formation ...... • . . . 129 10. Lake Tacoma, Lake Nis.qually and Early Lake Russell...... 132 11. Lake Skokomish and L~e Russell ...... •. 144 12. La1i:e Hood and Lake Russell ...... 147 13. Mouth of the Dusewalltps River Valley, drawn from chaTt 6450 of the U. s. C. & G. S., suowlng the Brtnnon Delta ..... 149 H . Glacial Lake Sammamish ...... 152 15. The Redmond Delta and Elnvlrons...... 155 16. Lake Snohomish and Ma.i:imum Lake Russell ...... , .. . •.... 158 17. Relation of the Richmond Delta to Lake RusseU e.nd the Puget Sound Glacier ...... 161 18. VlcinJty of Arlington and Marysville ...... 167 19. Profiles of the Glacial Lakes of Puget Sound, projected on a orth and South L1ne...... 169 20. Profiles ot the Glacial Lakes of Puget Sound, projected on an East and West Line ...... 172 21. Relation of Admiralty Sediments to Vashon Tm ...... 198 22. Oblique Truncatlon of Que.tsap Point Delta For:eset Beds .... 201 23. Interglacial Drainage Pattern ...... 203 24. North Shore of Hales Passage ...... 206 25. Course of Radiating Till Ridges on Wollochet Bay...... 207 26. Chambers Creek and Environs ...... 285 27. Diastrophic Movements of the Puget Sound Basin since Ad· miralty Gia.elation ...... 237 INTROD Tl
GENERAL PHYSTOGRAPHY OF THE p ·GmT sou.:n REGION. Tlle hn.in or ,1 pre i n of Puget und in we-tern Wo. h- ington Jies betw •n h Olympic Muunla.in on the we t and the a cade Mountain on the ea t. Iu it noi-tbern portion it open to the Pncitic cean through th reat valley cupied by the trait of ,Tuw:1 de Fuca betw en the Olympic fountain nnd Vancouver 1 land. The ba in i n lo al on the outh by a low divide be w n the. ound nnd the behali iv r, the latter flowing to tl,e Pit ific outh of lhe Olympic . The name' Puget ound" wa ori innlly ,..iven by Vancouver to thn porti n of th inland a.rm of th ea which Ji outh or the ' lll'row ' near Tacoma. , anc uver distin ui hed t o th r main portion o( the e inlet • Hood anal and dmiralty Inl ,t. Hi u a.g wn r pected by Wilk of the Tnit d tates Exploring E ·pedition a half century later but today the term 'Puget ound' emb1·aces all three p01tion and i fre qu ntl u ed lo in<'lude all marin · wnt rs conned d with the lroit f Juan d • u a outh oC the Int rnationa.l boundary line. In this bro11d en c it is a cd in the Litle of tbi paper. The dcpres ion of Puget ound i gcnelica.lly yn Jinnl, be longing to the mo t we t rn ,yn ]inorium of North m ricll. Tl1c Gulf of G 01·cria north of it, and the Willamette valley of r •gon the Great. full y of California and the Gulf of Cali f rniii utb of it nr likewi e portion of thi tructurnl hough. here are interruption in it, and rliff t' nt pttrts ha e doubtle s had different hi tori The Puget und deprc i n it.elf i pllrtially interrupt d by a mountain u pnr of LLe ,iscndes e t ndi ng diagonall 11cro s toward the northw t ju t nortl.1 of Lh trait of Jll/lll de Fuca. The nu,untf1in rnngc of Van- couver 1 land i rhn a continuo.ti n or the pur. Th nrca tudi d rt nds from tl1c lnt •rnational b unde.ry on the north to U1 divide betwe n Ute h bali nnd ·otnm it, ri er on th ou Ih a distance of 170 miles. and from the 10 Bttllettiln No. 8, Washington Geological wroey ba e of the Ca cade to that of the 01 mpics, i:n an east and we t direction this di ta.nee averaging 50 mile . outh of the Olympic , the hehali Yall y ha b en tudied from the low di vide between it and the ound ba in to the Pacific oa t. Though beyond the limit · of glaciation outwash from the Puget ound Glacier wa carried througl1 everal gap in the 1·0 k hilJs to the Chehalis River aud thence down the valley of this rjver to the head of Grnys Harbor oo the Pacific. 1he fore ts on the we tern coa t of rorth Am 1·ica., from Puget ound to Ala ka have been repeatedly de cribed as almo t tropical in den ity. ewben-y Russell, Willis and other 1vho have worked on the O"eology of Puget ound, note the r markable luxm-iauce of the fo1·e t and their almost im penetrable character, except along routes of travel. The pre ence of this primeval fo1·est over a c011 idm:able po1·tion of the country embraced in thi. tudy ha offered the greatest difficulty encountered in i.ts pro. ecution. It ha beet:1 po ible to examine many large area onJ along raifroa.d grade road ' ay and tTail a.nd in ucl, case no detailed tudy wa at tempted. Burned-o er or logged-off lands of Puget Sound, u.nle taken up for ~gricultu1·e, ar u uall quickly refore ted and th second growth i almo t a g1·eat an ob truction to the tudcnt of topograpl1y as is the original fore t. Fi-ve nited State Geologic l urve map have been made thus far in the area embrac d in this paper, covering about three tenth of U1e whol . ~ b ence of uch mo.ps for the larger part of he region ba been an ob tacle to ati factory interpre tation. Altitudes have been determined hie-By by aneroid u ing railroad profiles largely -for che k tation . A fen· United Sta.te G ologica! Survey bench ml.nk have been available in ome part of the region. Much of the country along the in let ha b en examined with no better ch ck tation than the coast line with it tidal rang varying with ea on, locality, tc. PREVIOUS WORK ON TH:E SUBJECT.
1845 B.All:L:Es WILKE • aptain barlc Wilkes of the "United tates E:\.-ploring Expedition," now known by hi name, Glaciatum of the Puget ownd Regicm 11 spent seve1:al month in urveyina Puget ound. is mura- tive, , ol. 4, pp. 313 and 415 ref 1· to the puzzling m und on the outwa h plains outh of the ound.
1873 G.EOI\ n Gm.n . Thi nuthor publi bed an ac ount of a g ological reconnai a.nee of the northwe tern bountla.ry 0£ th cited tate in the Jow·naJ of the .American Geograph ical ociety for 1 73. He de ·ribed and figured the .monnd. of tJ.1e o\1twa h prairie gave ections of the drift of Puget ound and noted elevated marine terrace on an Juan I land.
187S and 1874 Jo El'B' LE O:N'l''.E. In a paper entitled On the Great Lava Flood of the Wet and on the t:ructu:re and Age of the Ca cade Mountain " publi.hed in tbe Pro eeding of the a}j£oroia Academ of ci nee in 1873 and in more complete form in tbe .American Journal of cience in 187'4, Jo eph Le ante di. cu sed the origin of the Puget SoQud fiords and the g ne is of the mounds occurring on the plain outb of the OllOd. He recognized the occurren e of a Glacial a Champlain and a Terrace epoch in the region.
1884 J onN EW-DE1UtY. paper pre ented by John ew- berr bef r tl1e e,v York Academy of cience, entitled ' On the rigin of the Fiord of Pug t ound , i printed by title in the ' Tran action ' of tha.t bod for l 84. Kimball, noted be low C'reruts wberr ,vith the idea that the Bord were glacially erod d by northward flowing ice, and with frankly confe ing the mounds to be inexplicable. 1 93 G. O. Roo·n . The American Geologi t. Vo]. II • o. 6, ontain ruJ article on the ever popular ubjcc of the re- ma1·kable mound of the oul;wa h 1·egion of Puget ound. The paper bri fly de cribe the e form , di cu e various hypo the e for their origin, and Add a new one to h li t.
1897 J rn P. Kll\nULT.. In the American Geologi t. Vol. 19 o;;. 4 nnd 5, thi ob. rver d 11cribes the '~h iographic Geology of the Puget Sound Ba in. He con ideT a Pliocene ba elevelling to have preceded the Plei tocene, a.nd further excavation to have been accompli ·hed by later glacial ero ion . H! Bulletin 'I\ o. . JV ashington Geological urvey
But one glaciation i nlluded to. Po t glacial tream ero ion produced the valle now o cupied by the ound. Po t glacial crustal movement thu hnve been (1) an elevation, (2) 11 sub- idence and (8) from the p1· ence of raised beaches, a slight re-elevation~
l 9'7 B.m.n ILLt . paper publish d in the B Uetin of the Geological i t merica ol. 9, n itl d ' rift Ph nomena of Puget und Willi present" hi generaliza tion of Puget ou.nd" rr1Aci11l hi tory from work on th Tacoma quadrangle. FoUowin , Ru ell whose note on hi r gion were never publj h 1 h distiagw he b o gl11 iation and makes inference a to the character of the intergli-1.cial epo h. The ntact of Puget und i e with Ca. 1id ic i partially drawn Yariou features of the last glaciation ar d cri ed and the origin of the fiord-like valley and their eparatiug high land i considered.
l 99 BAILEY Wrtt.1 .U.'D EOllG.E Ons MITH. To.coma Folio o. 54. olo ical urvey. The Ple.i cene his- tory of the Tacoma quadrangle i de-cribed in detail.
1904 WARJtEN UPTI.AM. American Geologi t Vol. 34 o. 4 . The article here noted on "Glacial and Modifl d tift n ar o.ttle, Tacoma and J mpia. wa based on too lit le field work and much of it is in nor.
1905 ALBERT RE.Ao :::.. Kan as Academy of ien e. A de cription i given of ome Plei tocene and r cen feuture of U1e region between B Uingham and the International boundary and interpretation arc attempted.
1908 WA11REN UPHAM. A brief paper comparing the Puget ound coa t line with thnt of the SagueDO.y River. Ab strach published in Sc-ien e. 1910 J. H. Bn:ETz. preliminary paper on the 'Glacial Lake of Puget ound. • Journal of Geology Vol. l o. 5. 1911 J. H. BRETZ. "T rminal 1\foraine of the get ouud laci r.' Journal of logy, Vol. 19 o. 2. CHAPTER I. OUTLINE OF THE PLEISTOCENE HISTORY OF THE REGION.
SYNOP81S.
CHARA.OT.EB. 01!' THE PLIOCENE. PLIOCENE ELEVATIONS YE'l' EXISTL.-.G IN TR:E BASIN. Ei>ocxs ol!' THE PLEISTOCENE KNoWN IN WESTEllN W ASR- INGTON. ADMIRALTY EPOCH (GLACIAL). PUYALLUP EPOCH (INTERGLACIAL). VASHON EPOCH (GLACIAL). D1AS-T.llOPHISM OF THE PLEISTOCENE IN THE REGION.
CHARACTER OF THE PLIOCENE. Most of the formations outcropping in the Puget Sound basin are of Tertiary age, a.nd all of them south of the Strait belong to this division of geological history. Eocene and Miocene sedimentary beds record a shallow sea, with frequently changing depths and shore lines. Beds of terrestria.1 sediments are inter stratified with the marine, many of the Tertiary coal seams of Puget Sound preserving forest floors with tree stumps iin situ. The Tertiary Sound region was one of constantly shifting land and water areas, and of frequent alternations of fresh and salt water. Contemporary lava flows, both from fissures in the basin and from extrusions ,vhich originated in the surrounding areas, are intercalated among the sedimentary beds. For this region, the Pliocene period was primarily a time of die.strophic movement and erosion. The Eocene and Miocene beds were domed and folded, the whole area was lifted higher than at present, and subaeria.l erosion developed great relief in the weak Tertiary rocks already deposited. Further lava Bows occurred, of the same character as the earlier ones, but appar ently no "Volcanic cones were produced. H Bulletin ~ o. , TI a8hi11gton Geoloaical urucy
PLIOCE :E ELEVATION YET EXISTING I,' THE B IN. In the u ceeding l i t en great edimcntary depo it of glacial orjgin buri d th Pliocene topogra.phy. drift plain wa aggl'ad d whi h r ach d from one id of th basin to lh other. b ve thi ro i land-like, a few re ion f originally greater uplift. '!"he chief Pliocene elem nt of the r ent topography r ( ) he diagonal mountain , pur from the Ca cade aero to , o.ncou,·er I land includin the an unn Island group, (2) tb lu Hills betwe n food anal and dmiralty Inl , (3) wcu tle Hill and uak fountain ea t of eattle, an ( 4) h Black Hill Bald Hill and oth r marginal elevated area on th outh.
EPOCHS OF THE PLEISTOCENE KNOWN IN WESTERN WASH I GTON. Ru ell fir t noted the .·i tenc of two till h t nd of inter-till ediroent in Pug t. ound. illis later named the three recorded epo h dmiralty (glacial) Puyallup (inter gl cial) and Va hon (gfa ial).
AD UR 1/rY EPOCH (GLACIAL). Good ~rpo ure of th tilJ f the Admiralty glaciati n arc rar , there being harrlly l\ or in the man mile of ca-cliff on Pu ct ound. Th epoch e.nd it till are named from d miwlty Inlet, along wh 11or the till wo. xomin by both Ru ell and \\ illis. 'I he b~ e of the till, o !nr u known by the wri er i expo cl in but two or three plu in the ntir r gion an nowher along dmir-alty Inlet. illi note the nb ence 0£ evi enc of rlier glaciation , within he limit~ of hi tudy. Th dmiralty till, in po iti vcly identifi d e.xp . ur nowhe1·e d eply w ath r ll, hough in ome -place ·tt in d b p ' lating water. t p bbl , nr for the mo t part fin11 but de cay bu ofteued them in omc ca . Th e varinti n in the amount of weathering nppear o hin1e been d t rmin l b • the thj kne of co er o r th till of any Iocwty duri g th int r glacia.l epoch. To e tim t an e given of the thickne of the Glacia,tio-n of the Puget ownd Region 15 til1 hee.t, and the topography oE its u:rface i unknown. The character of the urface o er which the Admiralt ice e.dvanced i also w1known. A few expo urea of deepJ weathel'ed glacial drift have been found jll which t:he de.cay of nll but highly iliceou mate.rial fa:r mrpas es the Iteration of Admiralty till where the latter i dearly identified. u picioo ha iuisen from di covery of the e exposure, that a drift older tba.n the Admiralt xl.t in Puget ouod. - dmiralty till, howe,1(ff ha not b en idenlifi d m ection above the uppo ed older drift.
PUYALLUP EPOCH (INTERGLAClA L).
Exten ive tTenm aggradation occun-ed in U1e ound ba in 1.Lfter ll1e de.po ition of Admiralt till and be-for the advent of the foll wing glaciation. It is not au e..•u.1.ggerntion prob ably, to ay tlHlt nine-tentb of th Pl i to ene depo it of Puget onnd e..'--po ed above ea level belong to this ri . Tbe material is a orted lacia] d1·ift and probnbly wa deri ed largely from the won:ino dmira.Jt ice. Its b ds, u- po ed i.11 the pre ent ea-cliff , rarely retrun the ame haracter for inore than a mile; Jen tructur abrupt tran ition or gradual change in cha.rad r being the ru1e. In mo.n place fore t floor and wamp ed are pre erved in the erie as lie-uitic earns, and a few day beds at the base contain marine mollu can nnd cru ta e8Jl remain. . hcam bedding i common in ll1e gravels de1ta bedding i Ttu·e. In the outhern part of the ba in the trncture of the depo it indicn.t outbwn.rd flow 0£ the depo ii.ing water. A few intercalated till lenses prove that glacier ice , as till in the re ion. o indication are known of extended ub,m·ial ~'Po me of the dmiralty till before deposition of these bed . In brief n ,greo.t plain of terrestrial d po its containing a few marine beds in the lower portion, i conceived to hnvc been aggradcd in front of the ,vnoing Admfralty glacier, a it withdrew to the uorth. Thi conception i e ential1y similar to that advanced by Tan and 16 Bulletin No. 8, Wasliington Geologicai Survey
by Blackwelder for the genesi of the Yakutat foreland of Ala ka.• Following this e:den ive aggradation, uplift of the 1."egion, relative to sea level, occw·red, and a long period of atmo pheric e,~posure and tream erosion n ued. The gravels and ands became tained and locally cemented witb iron oxide, and near the surface were omewhat decompo ed. The impervious clays, howe'Ver, w,ere unaffected by the percolating waters which stained the gravel many feet below the weathered zone. A soil must have been formed du1·ing thi time of expo ure, but it has not yet been found pre erved beneath the later till. onsequent drainage developed on the sm·face of the plain. The outhern portion appear to have drained southward to the Chehalis River and G:ray Harbor, while the northern por tion sent its waters to the ea by way of the Juan de Fuca Val ley. A part of this interglacial drainage system can be recon structed today with considerable probability. Stream ero·ion v.dv1;1.:nced in the uncon olidated drift to sub maturity. The area became deeply inci ed by broad t1·tlllk valley , and minor tributar valleys were well distributed. on the divide slopes. A general north to outh orientation of main valleys prevailed throughout largely determined, presumably, by the original lope of the Admiralty drift plain. Willis name this interglacial epoch from stratified and typical of the sedimentary serie which, with Va hon till uncon formably overlying, are e;,rposed near the town of Puyallup. The sand truly are inte1·-till in po ition, but only their staining and the erosion of t11e w1Uey in who e ides they a.re ~·po eel' are con idered as interglacial. According to thi interpreta tion no iJlterglacial sediment are known in Puget Sound and the Puyallup interglacial epoch is to be con ide1·ed chiefly as one of -weathering and ero ion, o far a thl region is con-
• Tarr, R. S. "The Yakutat Bay Region." Professional Pa.per No. 64, U. S. Geological Survey. Blackwelder, Eliot, "The Yakutat Coa.stal Platn. ot Alaska," .Am. Jour. Sci. Vol. 27, 1909. Glaciatum of the Puget ownd Rcgicm 1 "{
ccrned. Presentation of the e idence fo~· this and other con du ion briefly o.ted in tbi chapter will be given later.
VASHON EPOCH (GLACIAL). The late t glacier of Puget ound advanced from the north, a did it predecessor the Admintll:.y the ice being upplied,.,../ largely from the snow fields of Bdti 11 olumbia. r6nly a minor pint of the ice of the Puget · ow1d Glacier came from the margining mountains, and tha portion outh of the trait of Juan de Fnca cannot be loo'ked upon as a piedmont glacier fed by valley glaci s from the Olympics and Cascades. Evi dence will be pre ented to how that the Puget Sound ice of the Va hon glaciation wa actually thru t up into some of these mountain valley , in the face of heir des ending glaciers. At the maximum, the ice of thi epoch extended at least as far as that of the dmiralty ep ch. Admiralty drift j found beneath one portion of the Va hon terminal moraine but no where beyond it. El ewhere, the fre h Vashon till of the ter minal moraine overlie rock apparently, never glaciated pre ious]y. A terminal moraine , ings aero the outhern portion of the depre ion from the Ca cade to the 01 mpics. A a topo graphic form it i insignificant in mo t places becoming here and there ll mere moraine t.crrac on the north ide of rock hills against which the ice impinged at its maximum and in oth r placei , e pe ially in valley , being larg ly buried by outwa h "'rllveJ. In its great t d velopment it apparent height i due in po.rt to buried rock hill who e tu.ta outcrop on the southern lope. Its course record the exi tence of two lobes of the glaci r front, the 1·e-eatrant being cao ed by th domed uplift known a the .Blnck Hill . Compared witn thi minol' moraine development, the extent of the outwa h from the Vashon Glacier i a.toni hing. Rela tively grent ar n ar covered deeply ,vith coarse, clean gravel producing broad ste1·ilc plain of low gradient. Two wide ptithway exi tcd aero the roe&. bill south 0£ the ha in of 18 Bullotim, No. 8, Wasl1imgton Geological urvey the ound at Gate and ab u Matlock. Thl'ough the e cbiefly, the gra el flood ent~ed the hebali alley, and a part of it wa canied to the bead of Gray Harbor. The Black Hills con titutcd the elevated area tancling be ween the e two path way. and minor gravel train were al o carried aero them to th hehali . Witl1 ravel entering the latter valley at cvernl p int along it course l:'llrli t by the iite Pathway, and later by the more we t rn ro\1te, an imperf ctly imbri ated erie of grave.I d po it wa con truct d which in i pr eut fragm ntary condition through ub eg\Jent trca.m ro io.o i difficult ati factorily to r olve into it component el ment . R ce. ional moraine and outwa h plain for a few mile. back of the terminn.J. moraine record a. varied histo1' of mar ginal drainag(l in the early ta.ge of retreat. Gravel plain adj u ted to po ible outlets at one po ition of the ice front were trenched and in ome ca e largely removed by the open ing of new cour e 11 retrcn progr ed or were abandoned and left a high-lying gravel la.teau with moraini depo· it, and ice-contact slope on their northern descents. On man of th e outwA b plain. , peci111ly tho e lo e1y a oC'iated with th terminal m rnine there i a remArkable devel pment of thou and of ymmetrical grav 1 mounds of fairly uniform size, clo el paced but of a ymrnetrical di tri bution and of hetcrogcneou tructure. M&ny hypothese ha e b en a.dva.nced to account for them but no one e:iq>lAnation is ·ttti factor . The writer lrn failed to find in pby. io(J'raphic literature an de cription of nnturul n1ound imil81' to the e, a.nd believe them to be unique so far as present knowled(J'e goe . The mound are 1·e olvable -into two typ . The origin of one type will be explain d but that of the th r remain an un olved problem. The c.~ensi-ve moraine and outwash depo its In.id down dur ing early n hon reb·ent appear to have mpletel oblite1·0. ed the int rglacio.lly rorled valley lying in th outhern pa.rt oi the Pu et Sound basin. The. produced ttn upland plnin notably different from the tlceply tr nchcd depre ion ontaining Puge-t Glaciation of the Puget ownd Region 19
ow1d. Farther north however, the supply of debri wa much le per w,it aTea, a.nd in mo t places a thin mantle oF ground mm·a.ine alone ove-rUe the interglacial topography de veloped in the Admiralty drift plain. The Va hon t.jU heet i thu largely a wide pread veneer of fre h ruaterial on the lope and ummit of the interglacial hm , lUld in many places on the flool" of the interglacial valleys. Locally, s~nd le de- po it of Va!:ihon till attain n thicknes sufficient to obscur the interglacial, i.tream-formed topography. Locally al o ero ion by the Va hon iee notably deepened the e trunk val ley . Thi deepening, however i submerged beneath the waters of Puget Sou:od, and i revealed only by the sounding of the oa t o.nd Geodetic u rvey, After the frontal margin of the Va hon Glacier had 1vitb drawn ome di ta.nee from the outhern region of heE.Lvy tiggr11d1;1. tion, it appear to ha,,e been melted back more rapidly than during the fir t few mile of retreat. Except at the outh the vaUey exposed by glacial retreat were little modified by outwash or recessional moraine depo it . The nggraded outh ern region, howc er prevented free drainage from the e valley into the Chebali . Wit.h a mountain range flanking the depre:-- ion on both the east and west, and w:i th the glacier complete] filling it north of the bared portion, the e vnlleys filled with water until overflow occurred aero the outwa h plain and through the Gate Pathway to the ehalis Yallt1y, Thu wa begun the omplicatcd history of the ice-dammed lake of Puget Sound. Further retreat e..xposed more vall J developed by interglacial tream.s and modifi d by the Vashon ice. uch of the e all y . a belonged to the river y tern whicl1 di cha1·ged through the Gate Pathway during the Pu allup interglacial epoch became a part of the glacial lake behind the divide of a. hon dri~, then but newly formed beti11een the ound and the hehalis Valley. VVher , however trot,gh belonging to the two other interglacial rh• r y tem of Pug t und outh of the Strrut wei·e fre d from ice they filled to the level of the lowest place 20 Bulletim, No. 8, W ashvn,gton Geological Survey in their borders aero. which they di charged to the master lake of the Sound basin in the Gute Pathwa valley system. Later, the retreat of the ice from suoce ively lower pa ses determined uccessive level in the e -independent lake . In most ca e , open connection with the ma ter lake was eventually ma.de, and all the lakes beca.me one. Though the Vashon Glacier left no definite rece ional moraine north of its aggraded plain until after tbe Strait of Juan de Fuca 1vas opened and the glacial lake were destroyed evidence of an o oillatory beho. ior of the ice edge ha been found in the l'ecords of the lake . These record are limited cb.ie.fl to de]t(l. and outlet channel , and the general rule i that lake level b come progre ively lower throughout the period of their exi tenoe. Where, how~ ever, a delta how alternating fore et and top et bed in the ame ection we have indi potable evidence of an abrupt ri e in ta.tic water level. 0th r data show this ri e to be due to re-advance of the glacier and clo ure of the lake's outlet. The large glacial foke of Puget Sound, by increase in length northward as the ice front retreawd, and by the addition of the area of former tributary lake , eventually became more exten sive than thn.t portion of Puget ound which lie south of the latitude 0£ Everett. In an earlier paper• this water body wa named Lake Russell, though its northward e..uent was not then definitely known. The northern margin can be drawn .now ,vith a fair degree of certainty. Eventually, the we tward-opening Strait of Juan de Fuca wo. cleared of ice, and Lake Ru sell was drained to ea level. marine water replacing it in ttie valleys whose bottom were be low sea level. A few glacial lake entirely unrelated to Lake Rus sell and bo the drainage into the Chehalis River, were formed a the .ice front. retreated acros the mountainous region which partially interrupts the Sound ba in. ucceeding the glacial lake of Puget ound there wa an epoch of submergence be-
•J. H. Bretz, "Glacial Lakes of Puget Sound," Jour. Geo1. Vol 18, No. 5. Glaciation of tl1c Pug t uumd Begum, tl neath ea 11ter. Thi introduc U1e abject of cru tal move ment in the Puget ound r gio11 during the Pleisto~11e. DlASTROPBISM OF .TBID PL1i11STOCiilNE IN THE REGION. The eurlier cru tal movement of the Pleistoc ne in thi •·egioo can be de ciphered only in their broad outline . The po t Vn hon movement . howe er cnn e d a1t · · b guontit tiv •ly. The land wa bjgb during the Ji c r re uma ly higher th n at ny ub equent. tim . If we I i i nally c rrelate the known glacial epoch o( Pu •t ound the lat st wo ( lhe northern hemi.phere a pltlu ibfo cor tion u great pai-t of the on.ternary period ha no 1· cord · the ediment- of the r gion. Altitude and mov m nt of the P uget ound ba, in for mu h of 1:.he Quaternary th r fore are unknown. i urther v ry litll i known of the dmirnlty glti iation. At th time of the r treat of tbe Admir lty ic , ho\ ev r, the re.gi n a sli htl_ • lower than at pr ent: murin rgaru m in he \dmir nll)· cdim 'n having been f uurl in Jtitu n few feet abo"Ve pr ·- 11t high tide. • arJy in the Puyallup iuterglncial epoch, the region wn probably a thou nnd feet high >r than now. Thi permitt d the tJ· 'l1tn of tha time to curv tl1 d trough in the .Admiralt drift plain \ hjch are now oc upi d by the Sound. At th maximum of Vashon glaciation oubn1 h gravels were pour w tward down the Chehalis as fat· as the pre ent head of ray H r or where they now lie 85 feet nl1 ve tide ith lrenm eddin . From thi we may cou ·Jude that the land 11 d 1 " •r d from it · high intergla.cilll po ition to one near that of tbe pr ent. ~ fter Va.hon retreat opened the trait, and urnrine water r placed Lake Ru ell in the Sound outh of it, ub e qu ntly outwa hed gravel w re adju ted to the new bltic water level ·. Though U1c videnc i not as clear fl could be 1 i hed tl1e ea appear to Jm v fiJJed the ound bt~ in and to have tood 50 feet or 1 a bo\'e the pre en t level. farine littoral hell lllLv b n Iouncl on the bluff· of uget ' und, in ome places accompanied y wtwe-cu.t terr ce ev r - wher v rlying the \ ashon till heet and in ~ome depo its 22 Bitlletim No. 8, n a. hi11gton Geological ur cy
lying on tbe Lake Ru ell delta , and even back in the valley of Plei tocene river di charging into thi lake. In the pre - ence of these shell there is positive evide1-1ce of a po h-glacial ubmergeoce of the Puget ound ba in to a depth of 250-280 feet more than now. hells are most common at the lower level where fairly definite strand rnay be wo1·ked out. The bjgher occurren e of littoral hells are rare and yield no more evidence than. that of the erity of the o cutrence. Data w-ill be pre ented in hapter X to show that these shell occur in situ. When the submergence wa 120 feet or more in e..'\'.ce s of the present, G.rn.ys I arbor and Puget ound were connected by tide water aero the ite of Lake Russell' discharge-way, and the Olympi.c Mountain on tituted an island. The topo grapbic effect of thi ubmergence are today almost nil. o definite shore Lines higher than 100 feet remain, no river delta of the time have been found and were it not for the shells, there would be n.o evidence whatever, to record po itively the higher level of the ea during tbi epi ode. ince trikingly developed river deltas record Lake Ru sell today, and ince el ewhere tJuoughout the region pot-Va hon tream ero ion has been ve1·y light, jt is to be concluded that no bore or tream features of prominence were ever developed during the marfoe ubmergence. We conclude therefore that it was very brief. During the dia trophic movement wbicb have submerged the ba iu of Puget ound to at lea t 250 feet below the pre ect sea level, and which have re-ele ated it approximately to it immediately po t-gfo.cial po itio11, the level of Lake Ru el] have not been appreciabl tilted or warped. The evidence for this couclu ion will be pre ented in hapte1· VI and CHAPTER II. THE TERMINAL MORAINE OF PUGET SOUND.
SYNOPSIS.
CONTACT OE PUGET SOU1'."l> AND CASCADE 1\foUNTAIN GLACI.ERS. 'l'HE l\lollAJNE AND THE NonTR-EltN HrLLS OP Tm:: Humc.LE- BEnnY ~loUNTAIN GROUP. TEI.E Mon.u..-.E ON 't'RE GATE PATRWAY PLAIN. TH.E B LACK lin.Ls AND ·rin: Mo.n.A!NE. '.f.FJE l\,fonAtN.E ON Tlra ~L\Tl.OCK PATHWAY. <..:oNTACT Ol' PucrnT Sou.ND a.""n OLYMPI C l\,l ooNTAL"< GucmRS. G.E11.'llilAL CoNsmEllATI ONs.
T he eastern and western margins of the Puget Sound Vashon Glacier are indefinitely reco t•ded in the glacial deposits. It appears that coalescence between the ice from the nodh and the glaciers from the Cascndes occurred in the northern part of the region, imd that no east and west margin can be said to have e..usted. Fa1iher south, lines of contact appea1· between the great cenb·al invading mass from British Colw11- bia, and the Cascade and Olympic glaciers which descepded to it from either side. A definite margin belween the area covered by the Puget Sound Glacier and the driftless sw·iace south of it is usually to be found. rl'he description of lhis margin is the chief purpose of this chapter.
CONTAC'f OF PUGET SOUND AND CASCADE M.OUNT.AIN GLA· CIERS. Froni the work of Willis and Smitl, on the Tacoma. quad rangle, Puget SollJld di·ift is known to overlap tl1e deposits of a Cascade pie contact between the two contemporaneou drift beet . Thi i not to e con idered as mru·ldng tl1e ontac of the two ice ma e , in e he po 'tion of uch contact h.iftcd and no one line can indi(.'ate it for all tage . The writer ha not worked in this region of the O ceola (Ca - cade) Glacier, and the work of Willi and mjth is ac epted for mo t of the acoma quadrangle. rror bas been found however, in their ma:pping o.f the contact between Pug t ound and Mount Rainier glacial ice i.n the outhea. tern po1-t of the quadrangle. The northern glacier pu hed well up against the flank of :Mount Rainier and it ground morai11e completely covers the drift hjll of the Pu(J'et ound plain which abuts against the flank of the foothills. o fragments of Mount Rainfor l1wa have been een in thi ground moraine, while bowld of various kind of grani e typical oI Puget ound drift arc abundant up t the ba e of the foothill. . Tl,e char acter of the till - it color texture degree of lirmne s and coherence, tructur and compo ition - agr with that of ill which i undi putably of Puget oun.d origin. This i tru of th counh-y for 11 few mil s outh of out.h Prairie about Kapow in and on the a t i.ide of the Obop glacial drninao-e channel at Eatonv-i.lJe.. The Tacoma folio map the li-c1e of on tact a 1·unnfog diagonally to the southwe t from the region of Orting but the contact re.all lies alor~g a line drawn almo. t Stl"t.>.1ght OU 1 from tbat place. hop Valley i a long deeply -inci ed m1u·(J'inal drainage channel wl,ich onnects the Pu aUup \ alley fr m a point two mile outh of Orting with the Nisqunlly River yalJ y a few mile outhwe t of Eatonville. It a tbe discharge.way for the glacial water of the White, arbon and Puyallup river from M unt Rai11ie:r while the Puget ound la ier blocked the lower drainage course ,vest and north. It also carried e ca.ping , ater from the Puget ound Glacier, much of wh.icli gath re iJl a high-level Jake in the Puyallup trough ubout Orting. A nearly north to south line from Orting to Eatonville lies frotn on t two mile we t of the pr bable ontact of the Glaciation of the P~tget oamd £legion !5 Rainier nnd Puget und ice when the latter , a at it maxi~ mum. It will al o appml..-imu.tel. divide the plain on the we t from the rock hills which 1•i e toward Mount Rainier on the east. Eatonville is built on early outwtl h grnvels of the Puget ound Glacier which reco1·d caping glacial water before retreat had b gun on the north aml northw ide of Mount Rainjer. The Puget ound Glnder at it ma.ximwn, however pu hed up on the roek hill lope ovedooking Eatou\'ille on the a t to an al itude of 1:60 feet above thi outwa h plain li60 feet above the a. fairly d finite moi·aine ridging bn k on the hill ummit here benr nn abundnncc of Pncr t ound drift material, uch a ·uriou gr nit I g1trn •tifcxou mica chi rt gnei etc. the pre ·enc of whi ·h in futin.ier glacial drift is unkno,wn and alto gether improbable. Ea - of thi terminul llloraine d po it at tLe top of the teep ro k lope, there i little evidence of any glacintio11. The region ar a magnificent primeval fore t and e.,po ure a.r aft'orded dnJy by overturned tr s and by shallow uts o.loug an old rOL-1.d b tween Eidom'ille A.nd Elbe. In ~pite of the paucity of dato. it i apparent Lhn Raini r glacial ice never altel"ed le region more than to remm•e a re idual oil . nly three erratic fragments were found along about ten miles of road. The i qually Ri er cruerg from the foothills five mj]e outh of Eatonville and en ler th Pug t ound drift plain at it mo · out.hen tern poi•tion. l'e th Rainier foothill on the a t and the altl Hill and the Huckleberry l\1 untnin on the outh form a right angle in the wountain wall o ei·looking the plain which lie to the northwest. The Pug t Sound Glacier crowd d up on hese lop a at atonville, and g,,anite erratic have been found a hjgh a 1,100 f t above ide. Deposits of the Puget mmd Glacier partially obliterated the pre-, a hon • i qua.lly Yalley at l:.hi angle and the po t glacio.1 trcam: failing to follow- it former cour e, ha subse quently cut thr ugl 40 feet of outwa h containing Puget ound drjft, and SOO feet into ande ite ltl:va. The canyon thus form d in the rock i a.· deep a it is wide \l'Lere cro cd b ~6 Bulletin No. , Jf'ashington Geological uro y the cabl footbridg nt 1·,mde. The gravel ab v the t n- •oo brink i nearly 1 00 feet above tide, the high• · altitude kn wn to have been attained by oub a h gravel · of th Pug t ound lacier. The r'v 1· i 1\ppiu·ently flowing ou the pre Vu. hon val]ey floor e.t 1h head of the can on two ruil . l,ove the footbridge at LeGrand . The city of Tacomn ha lop d l he wat r power re uJ ing fr m thi glacinl di,,er i n of h ri er our' b.' th . a vnt ion of n tunnel throu O'h th n nde it , t k ftoru the head ( tli> r11oyon to the de p ·t point at c- rand and the con lru ti n of pen tock and turbine at th t pln . 'lHFJ fORAI1 :EJ AND THE NORT • N HILLS OF THE HU KLE BERRY MO NTAIN GROUP. Th Bald Hills from L · ,rand w ward f 1· veral mile pr · nt a bold northcl'II foec toward tJ1e drift plnin. The c untry i den ely fore e'1 1111d Jjtfle i known of th• moraine in th: l region. Th hut River head in th un .. une~, d r •gion ]ying outh of the Bald Hill and flow out 011 th• ch-ift lnin f Puget ound w t of thi hill group. The north rn lnci r crowded back up thi nll y ornewhat impinging on both no.rlh and we t Iopa· f the Bald Hill . fin r valle. s. on the e lopes have b n dammed by the moro in , producing lake and mar.he.. One m•h ,•alley po es c lhl' e Illar he: d ending in order from :-outh to north, each with 11 perfect 111 min ridge dammin the wi.11 , and the high ·t wi h o,, !' looking rock cliff ri ·ing THE MORAI ~ 0 THE GATE PATHWAY PLAIN. A fairly definite moraine begins north of Mclnto h and wing westwal'd past T enino to Black River near 1\1:ima. It topo graphic prominence i not due entirely to its own ma s as will be hown nor doe it mark the ma,ximum e:d;en of ..the Puget ound Glacier throughout it length. lear Lake, at Mclnto h Station, lies in a pre-Vashon tream valley, which i drift dammed at the ea tern end. Altno t no drift is c ntuined in the valley. The rock hill wrucb consti tute it northern divide b a.r Puget ound till only on their northern lope . Yet the Puget Sound Glacier ovenode the e hill filled the Cleu.r Lake valley and crowded up on the hills outh of tlte lake more than 800 feet above it. cattered erratic pebbles and obblcs of fre h material cover these hill lopes up t.o 650 feet above tide, occul'l'ing more than a mile outh of the lake. No till however was detected on thern, t. Tenino, the same conditian obta:in. Rock hill north of the alley iu which be town lie are capped with till, and bear heavy till depo it with typical morainic topography on their .northern slope . How much i till and how much is rock cannot be stated, but the chance favor th predominance of till, The valuable Tenino and tone""~ quanied from the outh ern lope . But the Puget Sound Glacier cro ed the Tenino 1 alley and left cattered erratic on the ot1th ide of the valley a 360 fe t above tide 80 f eet above he town. H ere al o till failed to be depo ited on the outh_ ide of the valle . About hree mil e we t of Tenino Grand Mound Prairie i bordered by the moraine on the north and by unglaciated rock hill on the south. Though no erratic have been found on the northern slope of the e hill , evidence from the outwash gravels of this prairie and of the valley from T enino to th Skookum Glaciati,mi of the Puget S01JJnd Region !!9 huck at 13ucoda, indicate that the glacier abutted against the e hill at it ma.~imum and forced drainage to take a circu:itou course that it abandon d cnrl , in the retreat. The data on thi que tion are mor fully di cu ed in the following chapter. The only known inci. ion in the moraine ridge between the De Chute Rive1· near Mclnto hand the Einck Hill near Little Rock occur on and one-half miles ea. t of Tenino and at Mima Prairie. The tntn -m rainic hnnnel near Tenfoo never carried a. great volume of "·ater aero from tbe north and the exten sive oub a 11 ravels of the wo Te11ino- nmd Mound 1·oute were tlms depo ited by drainage direct] from the ice when i overtoppcd the monune. Th 15mu Prairie incision i. vir- tually a mplete bteakina own of 1e moraine topography perhap larl'l'ely l,ccau c pl'acticully all gltt ial drainage f1 m PuQ'Ct oUlld, from the earl r ece ·sional focre of ice retreat to the op ning of the trait ah t]1e north und the de&truction of Lake Ru ·s~U pn .ed aero the moraine 11t thi place. orth of Tenino th moraine ri. e to 550 feet above tide. 250 f t above it ba. e on eith r ide. n outcrop of hale appear in a road cut aero its ci· ~t, more than l O f ect abov the base of the moraine. 1'he width more than the altitude ap p ar to be a function of drift depo ition. It is two mjles wide nor h of Tenino and a few mil farther w t it increase to a w-idth of 11.bout four mile b ing in this portion witho t the rock outcrops at lower o.ltitude and broken into a number of eparatc ridges. The recent con truction of the Chic.ago .Milwaukee & Puget Sound Railroad through thi region ha afl'orded a number of valuable ections in the moraine. The railroad follows a route of escaping glacial drainage along the north s.ide of the moraine from Rocky Prairie to Little Rocle where it use the Mirna Prairie incision to cro to the outb of the moraine. Almost ev ery cut how the fre h Va hon till underlain by decomposed and stained drift of much greater age., and in ma.-ny places al o by rotted Tertiary hal . on idero.ble commingling of fresh and 30 Bull tint No. 8 Washingto11 Geological 11,,·vey decompo ed matcrjal oc ur , tJ1e fresh drif in ucb case being di colo1 d b iron ox:id from the olde1· material. Va. hon till · e.::.."J)o ed in road and railroad cuts betw·een Little Rock Md l\Iima Prairie. n the we t ide of thi prau:ic it overlie an old 1·edden and decayed till in a railroad gravel pit close to the ea. ter.n ba e of the d1·i!He Dlack Hills. THE BLACK HILLS AND THE MORAINEl, From :Mi.ma Prairie, th mar in of the Puget ound o-Jae-ial h·ift ha an altno t dil'c ·t northward cour for nearly ten mile , and in that di tance ri e gratluo..lJ higher on th flank of the Black Hills. W addcl l ree.k i a ou tlnni.nl-flowing trcam ju t within the ea tern mar in oi the ·e bill , e.merr,oincr from i;hem on Mirna Prairie. The hill ro ufficicnt]y high nbout it head water and o.lon(J' it a tern idc to bar the ic and drainage from the Puget ound lacier for mo t of the ream' length. But, tutoma.Jou ly tbi outh-flowing tr am \l"R ice dammed at it exit from the hill and t;hough the glacier never uc ceeded in enteri.n"' the valle glacial drninag wa turned into it from the lower portion, and the vall filled mtl1 wat r until an outl t I a found we tward to edar r ek. C(lttered glacial pebble are found ju the -re idual oil on the lop of Waddell reek valle lo an altitude o! about 650 feet the altitude of the outlet to e.dar Cre k. ove thi hcight, errati inF.lterial abruptly cea e . The highe t glacial drift found on th ea lope of the hill in the vicinity of the former dam i about 350 feet above tide though the ic mu t have been a high a 65'0 feet. Th ea tern lope of the Black Hills is densely fore ted and exc edingly difficult to xarnine. The present tudy ha been content to locate the upper limit of the drift in n ufficient num ber oi place to indicate the genel'al cour c and altitude of it mo.ram. l\Ioraine ridge are not known an where about the Black Hill . The re idual oil of the Bla k Hill· m triking contrast ,nth the drHt flanking it. It u ually on titutc a deep red Glaci.ation of the Pug ·t otmd Regi THiil l\rDRA.INE ON THE MATLOCK PATHWAY. From imp on ol the g lacier mnrgin wing in a wide curve, con\'e..x we tward o.cro the 1\ atlock Pathway to the outh ca teni foothills of the Olympic . It position is recorded by a few till hill ri ing above b gravel plain which hen dominates the topograpl1y. A definite cour e ma. ome da be found -in the e hill , but the pre cnt fore. ted condition and the lack of road lvn tdlowcd 01tly a r connai ance thu far and the moraine course is mapped on] approximately. The till in the . hill i imilal' in almo t Q.11 detail - to that on th northern lope of the Ila.Id Hill and to that of tllC' ground moraiue in the region of the Poge ound l'ougl\ . The uniformity of S~ Bulletitn No. 8, Wa.ahington Geological Survey character of the Vashon till of the Puget OlUJ glac.ier is re markable. Almo t everywhere, it i light bluish gray in ,color, arenaceous in teA-tlll'e, filled with rounded fr~ament of 11ock which re emble tTerun pebble. and which are seldom triated or pla.n.ed. It rarely carries bow Ider in i mas though uch are abundant on jts orface in me place . From the Black Hills to Matlock the till commonly how " a large proportion of deep red clayey material intermingled , ·ith fre h pebbles. The gravel of the Wildcat valle train likewi e p e a reddish color he sugge tion of age which it give being belied by the fr hoes in the interior of the pebbl . It e m pr bable tht incorporation of re idual oi l from the ba a1tic country rock i respon ible for thi co1oration. Lake o.hwatz l li es in the most exten. ivc morainic country known in thi region. Tbe g eneral e.....:pre ·si011 of the topography is identical with that about Clear Lake near the Bald Hills. M raine hills heTe rise 50 feet above the lake urface on all ide . The moraine i ne11.i. found at Lake Cushman in the koko mish River valley. It cour e between Matlo k and Lake '.u h man wa doohtle . controlled by the rock hills a.Jon"' the north side of the l\fiatlock Pathwa , and it i thu mapped. CONTACT OF PUGET SOUND AND OLYMPIC MOUNTAIN OLA- ClERS. The genesi of Lake u hman is intimately related to the Puget ound Glacier. The Ink lies in t,he- course f the koko mish River at an altitude of 00 feet, hemmed in by mountain w1,tUs except to the ea t, where a bwad di·ift plateau, from ':1,00 to 950 feet 9,bove tide lies between it and :a'oods Canal. Puget ound hown on the lope facing the lake are fore.ign to the drift de posited b the Puget Sound Glacie1·. The valley of the kokomi h River is thus seen to be dammed by e. gTcat deposit of the Puget ound Glacier wJtich here crowded up the 1·iver valley and held Lack the local glacier that nol'mally would have deployed in the Puget ound ba. in. The deposit of the local glacier in the kokomi h aUe give tl1e lakeward face of the dr· t dam it different cba.racter. A till daJ:ker than that of the Puget ound lncie:r, po e ing angular rock fragments of kind eotii•ely different from those of Puget ound drift lie back of Lake u hman on the lope of Mount Ellinor about 1 800 feet above tide. It doubtlc s is a deposit of a local glacier which o cupied the Lake ushman basin of tode. y. Views of Lake u hman and vicinity from the trail up 1\lount Ellinor show the relation described a ovc a.Imo t with the clear ne s of a diagram. From the socalled 'Hlllf Way Rock > along the trail it requires only a slight effort of the imagination to ee below one the dammed-back kokomisb Glacjer oppo cd by the mighticl' Puget Sound ice mas which crowded westward against the mountains. Lake ushman in early po t-glacial time wa much larger than at pre ent. The Skokomi h River i rapidly filling it with a delta whicb now has a greater area than the portion of the lake remaining. lnci ion o·f tl1e morainic dam ha lowered the lake level probably as much a 100 feet. .At it former altitude the lake must have reached con iderably farther back up the river valley. Stratified clay of the former highe1· lake level. are e.xpo ed along the tage road near the ferrJ, and a fine serie of river terrace i i ible from thi road a few miles be low the lake. It has not been practicable to determine clo ely the form and position of the Puget ound Glacier on the ea t £ace of the Olympic Mountain . Granite pebbles ~ t at least four mile up the valley of the Du ewallip River, and no granite in situ -2 S4 Bidletiri. o. 8, Washimgton Geological Stirney ha ever been reported from the lyropic 1ountain . The Puget ound drift cover th region we t of Dabop Bay for fi e miles or more back from the wnt r. It a o con titute the surface material on Quimpcr P nin ula, about Port Discovery, and between Port Di cover and Quilcene all of which are LD tl1e tl'Uctura.1 valley an LAGRANOE. 1?20 Mc IN TOSH 660 cl ~... ~ -;;;., 9... LITTLE R'OCt< ISO CJ E< =0 "'gj > SUMMIT LAKE. 1"16 QJ :5" 7 ... Cl> 0 ...J ., o3 SIMPSON 9SO 111 0 I» ~ 1/) ..; c {;; CLOQU,C..LLUM 4.SO MATLOCK 4.SO LAl Matlock Pathway lie about 1,000 feet lower than thi higbe t point that in the Gate Pathway about 1 300 feet lower. (See Fig. 1.) Tl1e thicknes of the Puget ouod Glacier nortl1 of the moraine region is not definitely known. ince the neighbor ing mountains were glaciated by ice of local derivation, the height of glaciated urface ca.n be no criterion. Jor can the height of erratic material serve our purpose, save where such material i po itively identified a foreign to the whole adjoining mountain region which might ha e contributed to former glacia tion. IV_fid-bas.in lulls of u:fficient height to have risen above the glacier are nece ary for an accurate e t-imate, and uch do not exi t. A hill which an wer the purpose to ome extent is .Mount Is aquah, 16 mile east of eattle. It i an i olated peak about 3 000 feet above ea level without the usual mantle of finely comminuted roc"k fragments found on unglaciated hills of the region. The comp ra.tive fre bne s of material covering the top i .in harmony with the pTe ence of scattered erratic pebbles on the summit, t1,e number of which increa e on the lower lopes. Both indicate glaciation of the peak b the Puget Sound Glacier. mce dmiralty Inlet attain depths of nearly 1,000 feet "'est of fount Is aquah, the total tlucl.-n.e of the glacier in the latitude of Seattle wa at lea t 4 000 feet. The only e,•idence of ero ive action of the Puget Sound Glacier near its margin are a few in tances of incorporation of weathered material from the pre-Va hon surface into the fre h Va hon till. Knobs of old drift and hillock of decayed hale are seen beneath the Va hon till .in many place with no sug gestion of deformation from tlm1 t of the overriding ice. This, of course, i not true ome di t.an.ce back from the moraine. Pre ent data how that the Vashon glaciation of Puget ound, probably to be qr-related with the Wi con in glaciation ea t of the Cordillera wa fully as extensive a any preceding glacia tion of the region. The tel'minal moraine from Mclnto h aero the Gate Pathway pJain to Little Rock overlie a former region Glaciation of the Puget Sound Regi® 37 of low hills of old drift, some of which j undoubtedly till. o old tiJl has been found outh of the moraine limits, and no obvi ou ly old and weathered erratic are known in positions indica tive of farmer and more ex ten ive glaciation. CHAPTER III. EXTRA-MORAINIC OUTWASH OF THE PUGET SOUND REGION. SYNOPSIS. THE PnE-VasHON R1m GR.Av.ELS OF T.ff.E CHEHALIS VALLEY. ADMIRALTY GucIATION AND THE CowuTz VALLEY. VASHON GLACIATION A.~.D THE CHEHALIS VALLEY TRAIN. SKOOXUl\! CHUC'!{ GRAVELS. ST0.11.'Y PoorT VALLEY TRAIN. T El In the two kno,rn glaciations of the Puget Sound Basin, the invadi11g ice came from the Cordilleran Glacie1· of British Co lumbia, and advanced sufficiently far southward between the Cascade and Olympic mountains to close effectually the basin at the oorth. Water dischargiog from the Puget Sound region was forced into stream valleys lying south of that basin. There ate two river valleys to be coosidered in this connection : the Cowlitz nnd the Chehalis. T he Cowlitz Rivel' heads in the glaciers on the south side of l\Iount Rainier a.nd flows west to the stm ctura1 valley of which Puget Sound is a part. H ere it turns south to enter the Columbia. There arc two low areas across the oortbern divide of the Cowlitz Valley where glucinl drainage could have entered it from Puget Sound. The Che- Glaciaticm of t'Tie Pzigot ound Regi<>71 S9 bali '\ alley head in the low con rang . outb of the lyu pie d cend tbci:r ea tern lop to the . ame huctural ,•alle ' which it a:i er 15 mile north of th enhance of the owlitz Vnlle . He1-e it ha a nortlnvard cour e for 1 mile· and then wing· about to a we tward cour e outb of th Black Hill· whence it continue to th Pacific. Th 'helutl:i, Vall li clo ·er to Puget ound han the owlit~ alley and between it and Puget ound there are several gaps in the rock hills two of considentble width. The e gap afforded ample opportunity for the entrance of glacial wat · in th va1ley. TfIEl PRE-VASHON REJD GRAVELS OF THE CHEHALIS VALLE . The maximum extent of the Pug t Sound ~ dmiralty Glacier i not known. Id rirt, -pre umo.bJ of AdmiraltJ· age, und r lie the Va hon terminal mor tine i11 the ,,i inity of Littl R ·k but is not known ueyond that locality. Tliei-e i , however an old gravel depo it in the ChehuJi. Yall y found n~ intenrat~ from Gate t the ocean and be.i1 ·e along the coii t ·hich i. vcr probo.bly Pl i toe ne in age, and a portion of which may he outwa h of the Admjrnlty glaciation. The mort ea, e.rn remnant of the old gravel known 1\t pre C!nt is at H iug Junction on the oulh ide or the Chehali Valle· oppo it Gate where the Oregon- a. ·lungton Railroad aL1d a\".igation ompany and. the hicngo Milwaukee and Puget ound Raib ay unjte on their common truck do",i to Grny Harbor. Th ra. 1 ci,p the blu.lf above the .rai]wo.. gritde o.lortg the river for two mil . It maximum thickne s i 35 feet and it overlies the Tel'tiary hale unconformubly with the conttl.c about 1'1'0 feet abo e th ri el' nl](l nbout 190 feet above ide. The gnwcl i d cpl tain d by iron oxide, po c - ing a true · ferrett.o color almo t throu0 hout. I ebble o.re o ·oft ned b deca that a blow of the hammer ,vill bren.k them ea, i1 . Mo t of them can be caned l\;t11 a. knife Like 11ardened clay. The bedding i horizontal. No granite, nnd no metamorphic or edimentary rock w re found nmong tbe peb bl ·, the depo it being compo ed aLHo t ntirely of fragm nt of ande itic lava. 40 Bulletvn l\ o. 8 Washington Geological Survey A deposit of cattere.d gr11.vel on the north ide of the 'hchali River lie a mile we t of Oakville at the summit of u. quarry ection perhap 160 feet above tide. In thi grnvel, gro.nite is abundant. Tl1e p bble are som wha softened on the surface but are firm within. The are less tained than the Helsing Junction gravel appearing fr her al o than the old drift near ittle Rock. Th are howev r older than Va hon out wa h \ hlch lies a a broad terrace a the foot of the liff. Th re are everal occurrence of fhe re gravel about Elma. It i Jound on Wild at Creek at White fill, and here pos e e current b dding dipping outhward down the pre ent valley in which it lie . It con titutes he larger part of a great ter race which form the north ide of tbe hehali Vu.lley :from Elma to Sat op, with a ummit level of about 3fl5 feet above tide. It i well expo ed a mile and a half we t of outh Elma, on the joint lin of the Oregon-WLishington and Chicago Milwnukee and Puget Sound railway . Here jt bn e i 100 feet u.bo e tide and its summit con titute a considerable plain urface probably to be correlated with the terrace on the north ide and visible fol" several mile from the north ide of the valley (Pl. I, Fig. 2). The decay and taioing of the gravels in this cut are comparnble to that of the Rel ing Junction. gravel , which the re emble also in compo ition. More of thi early gravel filling remains in die vicinity of Elm and at op than at an othel' place in the he.halis alley. This al o appear to be the only place \ here the urfa.ce of the fillit1g i till pre er ed. A mile , est of at op village, a prom.inent table-topped pur projecting from the north ide of the valley (Pl. I Fig. 1) i composed of thi red gravel. It ummit is 180 feet above tide. and its thic:l,'Jle. - is about 90 fe t. The atsop River, which enter he hehali Valle here bas eroded 15-9l0 Jeet below the ba e of the gravel and has e.'\.-po cd the.ir unconforro nble contact with the under! ing Tertiary and tone. On the top of the terrace the red gravel h been excavated for road ma teriaJ e.nd is appal'Cntl identical in degree of decompo i ion in tructure and in compo ition with the Helsing Junction and the ( 1 141\ 'l'f.: I F111 . 1. 'l'lle SatsoJJ n cl 1·nv l T rrace. 'l'h,• high 1'1'11 l,'l'OWl I 'l'l'll('I' 011 the $01111' •l(lf• f I Ill' l" l1~J,a!J rau h,• r11111u.1• •'I'll. F in. "' u1·rn.ce or r,tsop Ii cl Gm. el '!' rrnc . Frn. :1. ·Liou or Red rav I In al-op 'f rrac . "i'IJl\ 1,tru \'PJ ts d(lcolorrrl 0How1 1hf" lrr(Agulnr I rnll""-\'••l'"N.c• Iltw. hut I~ n mut1b ,J1 1cuycd u 1,r lnw. 'urr •ut hL- South Elma g1·ave) • Locall it urface part are complete! taining is pe1·ceptib]y greater near th top, the bu. al tro.ta b~ ing in place a.Imo t Lm tain d. The a.rue gradation i . howu in the oftenin by decay. Near the sit of the old ra. Harbor Cit , a median bed of clay lie b tw en two g.ravel members. Ero ion urfuee pnrnt the thr e. artber we t, one ection how verul nlterMting b d · of r d cla,y and red gravel ach b •a.turn averaging fom or five feet in tb.ic1me . Jame I land i u. pictu1· que tack of tl1e red gn1.vel I ing off the north hor of the arbo1·. R cl tained partiaJl decompo ed and partiall ceme.n ed graYel of tlte a.me character u that of the hebali- alley is known a.long the Pacific o t north to the trait of Juan de FuC!l. B t, en Gray Harbor and Moclip at lea t it corupo n forela.nd 11bou-t 12 miles wide. Wherevei· tl1e ba of tbi old gravel is een, it re t un on formubly on Tertiary formations. In di tribution, it j limited to valley and the coa t line. Di tortion of tbe underlying trata i ommon but no di tort-ion i k-t1own in the graYel it elf ·uve a outh Elma. ,vbere a liue ba evidet1t.ly been h cau e. The conclusion ·cems probable tbat the e red gravels arc Plei to cene tr am depo it in the Pliocene or early Plei tocene he hnli Valley and on a Pliocene or early Plei tocene wa e-cut coa tal heir. Their cl cay a.nd .taining are omewhat greater than that of known • dmira.lty O"J'll el. i:n th Pu..,.et ound ba in and with one e ·ception no granite or othel' ro k ha been found in them by which they could be identified with Pug t ound glaciation. The 011e exception the akvill quarry ·e tion it lF foil to onfonn a.ti factorily to the otb r e.-.. po ure. ~or the pr ent, thel'efore we mu t conclude that ·uf.fici nt e ideoae i. not known to show the e old Plei tocene gravels of the hebali to be related genetically to the .A.dmiralt glaciation of Puget ound 01· to be glacial at a.11. ADMJRALTY GLACIATION AND THE COWLITZ VALLEY. ince the pa e from the Pu,,.et und to the owlitz a11ey are higher and fa1·thc1· d.i ta.nt than those of the 11ehali it Glaciation of the Pu,get ownil Regio1i 4S seems unlik 1 that th owlitz r eive ou wa. h of th..i glacia- tion if ucb faiJec.1 to ent · tu o old drift of an kind i known at present in t.hc owlitz \ all y. VASHO GLACIATIO AND THE HERA.LIS VALLEY TRAlX KO K .:1.1 H K" GttAV'P.l • Th kookum huck River head in tbe un urveyed Huckleberry :i\lountuin , which lie outh we t of Mount. Rainiel' b twe n Pu t ound and lhe owlitz Riv r, and .flow we twarcl t join th hehalis nt ' ntrnlia. It rou lily parallels the Puget ound terniurnl moraine for ome di tance lying a few mile outb of it. It cour e, bow ver i within the T rtinry hill r ion outbea t of the Puge ound ba in. For mo t of it lengtl th ~c hill Yo c sufficientl hi<>'h to preyent entrnnce of dnlina.g from the lo.cier whi h pu hed up oa their 11orther11 ftu.nks. The tream vall y \ here tbu protected however po e · e a con idcrabL quantity of griwcl w11ich appear to hn e been o rapid] inh·oduc d that derange ment of dntinage followed. n abandoned farm known a Iu] queen (Fig. Q) lie' ome mile up the kookum hack , all y on an nlluvial flat among th rock hilJ . Immcdintely below thi the ·trerun enter a r,,orge with vertjc(L) wall appenrin l"I' to ha e been fairly r centl upcrpo.ed on a rock pur into which it ha cut. ucb an incident ould Joa,j u.lly follow er ion of a vo.lley tl'a.in, But a ca1· ful earcb for i mile along thi length ha failed to bring any Pu et ound d.ri ft material to light and the flat at Mulqueen lie 1 0 feet nbove the Puget ound moraine directly north of it. The filling, whatever it· ourc i not to be referred to the glacin ion of Puget ound. TO IY PoINT ALLEY TnAI •. There a.e till' e gap through which Puget ound outwa h dicl ent r the kookum buck Valley two of them of con iderable ize. ( ee Fig. !.) The mo t a tet·ly of the e will b de ignated the tony Point gap. At th mnxinmm of , a hon laciation outwa h from the entil margin of the glacier lying ea t of thi gap entered the koo kum Chuck throul'l'b it. The outwa 11 built a gravel train which contain many granite p bble and other Puget ouncl drift ma- ' I I \ \- - I ' ' 1- - _, _ I '( ' I I-The Gate "Pa\hwQy i:-Ten·,no -Bucoda Route 3- Glacial LaM Soulh o( Mc lntosh 4-Slony Point Channel S- La.Ke Cheholis 6-Gla.c·,al Lake of Waddells Creel< ll'10. 2. Olnclnl Uru.lunl{ll from tho Ew;tcro Lobe o! l'uget Sound Gloclcr, nt It~ Mllrlmum J!lz.tcnt. Gl(Jciation of the Puget Sound Region 45 terials. The coa.r ene s of the gravel is probably re pon iblc for its unlore ted condition. The altitude o( th col in the. tony Point gap ha not yet been accurat~ly detennin l, but it Jje below 350 feet. l ar Lake at Mcinto ·b ttttion altitude 346 feet, was never used by marginal drainage tbouah as the ice withdrew from it maximum tand the Jake valley la.y in o fa orable a position and at such an altitude that the gap was earlier held to have been unaYoidabl o u d, in pite of the ab ence of glacial gravels. The onJy explanation for outwa h holding to the tony Point channel until a route on the north ide of the hi]l north of Clear Lake was opened we tward is that the tony Point channel ,vas lower than the lake. Hence the confidence in the inference regarding the altitude of the gap. From the col to Bucoda along the valley train the di - tan e i 11 miles, and the de ent cannot e.'!ce d 100 f et. Thl i a grnde of less than 10 feet to the mile. A few miles west of the Stony Point gap the glacier clo ed a northward descending valley and produced a la'ke who e di - charge was south to the Skookum Chuck. But ince thi lake eaught 11 11 outwash ""ravel , the gap u ed b the outlet was unim portant in building the- kookum Chuck valley train. TENINO-GRAND Momrn Gu.CIAL DnAIN G-~ RouT:&s. The Tenino-Bucoda ap j the large t of the three which led glacial water to the koo.kum huck. Together itlt the °'kookum huck Valley belO\ tl1e poin of junction it con titute a through va.JJey from Tenino to the hehali at entralia. lo thi there wa probabl • a preglacial lO\v divide. 'I he greatest constriotion o<:cur ju t outh of Bucoda nnd it i po ible that the pl'eglacial kookurn huck turned northward near that town and flowed to the de-pre- ion now occupied by Grand Mound Prairie. A triangular dri£tle area i sul"rounded b the Te nino-Bucoda-Centralia gravel train on the outhen t Grand Mound Pn:irie on !:he north, and the gravel-6lled h hali al ley on the outh\,e t. ( ee Fig. ~ and Pl. XXIJI.) utwa h from the viciruty of Tenino ,vbich took the Bucoda route round d the outhern tip of thi area and returned to Grand found, 46 Bu,llet·in J:i o. TV asllingto11 Geological 1.wvey from whence it wa carried to, Gate and down the hehalis Val ley. Th di tance from Tenino to mnd Mound by thi c.ir cuitou. route i 16 mile and the de cent of the g1·M· l floor in that di tan e i u~ feet. lonO' Grand Mound Prairie on the north 'de of tlli area tJ,e di ta.nee i nine an one-half mile and the route i tra.ight. Outwa h \ ould nc er have taken the longer route ,vith ·o low a gradjent if the more direct route along Grand found Pn"Lir.ie had been open. The only cau e which could have operated to clo e it i ad,ran(·e of glacier i e from tJ1e po it.ion of the teuninnl moraine bordering tJ1e prairie on the north un iJ it io1pinged on the triangular hill t.1.rea. Though no rrtttic mat rial ha been found on the northern lope of the e dri-ftle bHl , the grade of the .,.ravel outwa h make it obviou that the Puget ound a hon Glacier at it maximum a tua11 ' reached thi po ition. The grade of thi Tenino- entraJia-Grand Moun floor i sUl'prisingJ Vtll'iab1e. .Between Tenino nnd Bucoda it de end ·x feet to tl1 mile· between Bue da and ' nb·alin nearly th.ir te n Feet to he mile; and from entr Iia to Grand Mound the descent i llut fiv f et to the mile. Thi la . gradient i prob abl of no value ince the vicirut of Grand Mound received grav L from the north after transportation b the Te11ino- entralia route cea ed. But the change ~ gradient near .Bu coda in a grav l rain which today floor · the entire vall , and obviou 1 i pra ticlllly the urue s. when abandoned by the glacial ri er need e::-..l)lan11tioo. Two h rpoth are ad vanced · one that the to:ay Point gravel train which entered the tlu·ough valley nt Bucoda wa of o much greater volum that it virtually damm d the Tenino-Bucoda 1 ngth, the other that a pr Va hon rock di,ride e._"G ted in th ornewhat con trict cl valley ju t outh of Bucoda and erved to back up the gravels to form a lo gradient. Fragments of a higher gravel filling Ue 810 to 8!0 feet above tide on both id of the valley at Tenino and cnttered glacial pebble occur up to 360 feet. The !80 foot terra e on which the town i built i continued without break toward Bucoda but GZaciati()'Tl, of the Puget ouncl Region, 47 end u.bruptlJ witJ1 a 30-45 foot de cent to catter reek val ley, wbfob lead westward along Grund l ound Prairie. mile or o we t of Tenino only a broad median ri g e in the axial part of th pwiirie re.main at the le\'el of Tenino the lower ul·foce 1 ewl1l're recor ling th later work of g lncial drainage along the dir ct route from Tenino to Grand l\.found. The prairie surface is undulating and no one figure can be given for it gradient. From th broad bottom of ca.tte.r reek at Tenino to Grand Mound however1 t] e i scent i not ciwte ten C e't to h mil , and U1' may be tak n a nn approximation of the gradient of the gravel- a1onb Gn1ud found Prrurie.. Tai; G ,\ TE PATHWAY. The Gate Pathwn from Pug t ound to the heha.li River i folly eil7ht mile in width. It i inter rupted by the i olated hill from which the tation itnd the pnurie of Grana Mow,d are named, and by u plateau-like ou ·er about a mjle in diameter near Roch ter. The gra cl plain of 'a hon outwn ~1 completely urround eac11 bill. Tbe plain i highest on the ea rn ide of th pathwa , and low t on the we t at Gate thi being ecau e glacial wnter ent I' d it on the ea t and northeast and tlowed diagonnlly aero s to the we t and ·outb we i and al o becau e a the volume of e caping wat r waned it beCD.me couccn rat d on the we tern _portion, perhap lowering th.i till morl!. The altitude of the mounded "'ra el prafri at Gute i ttbout fl feet tlbove tide, and it j 40 mil di tant from the mo t we tern occurrence of Vashon gn veJ in the Che baJi Valley w·l.rich lie nt SO feet alio e tide. Furthermore gravel terrace which contain Pu.,.et ound Vn hon mnterial ituated fat· down the valley lie a high or nearly a high, tl" at ate. It i immecliately obvious that no one imple gravel train can embrace the e diver cly ituatc valley tra:in in the hehalis. In each of the e tributary train the entering gravel "l\1a higher than the wface of the out1 ash (J'ravel which lrn.d entered some di tance. farther up the valley. By relays, a it were, the a hon gravel succeeded in reaching the head of tide water on the Pacific oast. ( ee Plate xxm for area1 di tribution of the e di..lf e.ren t gravel . ) GATE VALLEY TnAIN. The remnant of the Gate tl'ain con stitute an almost continuou t trace urface from tlle. town of Gate we tward to Malone ,; here it blends with and become ob cured by the younger Mock ChehaH train. Gate or Baker s Prairie Oak,-,iJ1e Prairie, edarville Prairie and Ford Prairie are portion of \he Gate train. Smaller fragment al o e:xi t in the valley mouths of Cedar and Porter creeks. The topoaraphy of about half the prairi area of the Gate train i remaxkabl mounded. The genesi of the e mounds i treated in hapter V of tbi, paper. Their presence involving a relief of a much a SO feet, with many delta-formed terrace and other irregularitje of doubtfnl origin, make the construction of a sati factory profile for thi rain almo t impo ible. Under the limitation. of thi tudy it ha not b en attempted. In general however the gradient of thi train is urp,risingly al most unbelievably low. The longe t di tance between bench lilark on thi train i from Gate to Porter. Railroad altitude are J1ere depended upon, and they give a (J'radient of i and one· third feet to the mile. The gravel, wherever shown, i hori zontally edded or po e a we tward dip, and the material was -undoubtedly tran ported by running water to it pre ent position. In consideration of the m.inimum grade a gravel train may po se , the pre ent Chehnli River grade js in tructive. Thi stream de ce:nds about four feet to the mile from He1 ing Junc tion to at op, a.t the head of tide water and is today weeping the re.handled outwa h grave.ls eaward along this tretcb dur ing flood ea on at lea t. The glacial Chehali , receiving at Gate at lea t hall of the drainage of the Puget Sound ba in south of the Stra:it, was thus pre umably capable of carrying the gravel of thi valley train even on the lmv gradient noted. w.,SU IN(;'j'{IN C:EOLOOICAL SPnVEY B trLLETlN No. S Pl.M't: 11 FIG. 1. Mound Section in Northern Pacific Railway Pit. Mlma Prairie. Doublu conYex rorru of the block sllt. Clean strntllicu griwel below. Frn 2. Mound Topography on 1\[ima. Prairie. Glaciation of -the Puget Sownd Region 49 Terrace occru· along Porter reek for a mile above its j unc tion with the hehali . Their material i entirely of local deri vation but they are believed to be contemporaneou with d posi tion of the Gate train. Here tbe gnwe) flood dammed the trib utar valfoy which in consequence wa · aggraded by b·eam debris brought down from its unglaciated upper cour e. Though Porter CJ-eek i the only valley Jo1own at pre ent to ho~ this filling it i to be expected in man tributary valley of that portion of the Ch hali affected by glacial outwa h. OuT\VASH WES'l' OF THE BLACK Hn.1.. . The function of the Black Hill in the production of the double lobe of the Puget Sound Glacier ha been noted. In crowdmg up on the northern flanks of these ]1ills the glacier overtopped low divide in two place and ent lender train of fre h light-color d glacial gravel oulhwn1·d along tlie tream valleys. The gra el of these trains i in remarkable contra t with the blaclc pebbles and deep I red re idual oil derived from the ba.saltic bills. Te::& 1\focK REH.ALIS VALLEY TR.AIN. The mo tea tern of the e valley train is that of the Mock Chcliali , a creek enter ing the Chehali at 1\falone. Two tenaces of glacial gra el occur at t1,e mouth of Porter reek and Cedar Creek but uch are simply remnant o-f the valley tram filling , hich entered by the Gate Pa.thway, and the e creek valle above their mouth are entirely without glacial gravel. The Mock behali train begin somewhe,re in the fore ted region of umm.it Lake. No altitude are known io it valley and it grade has not been deter.mined. It exi tence ha detennined the location of a number of fa.rms along the stream while both Porter and edar Creek val1ey , la king the flat bottom are yet covered by U1e primeval fore t. or but party logged oft' and have no farms above lheir mouth . Most of the fock Chehali train till bears the origina1 fore t, and no higher terrace have been found except at Sine and again near the head in the vicinity of umm.it Lake. Between Sine, on the l\lock Chehali and McCleary, on ildcat 50 Bulletin No. 8, Washington Geological Survey reek a tributary of the Joquallum, the rock hill fi.ui and a bToad, fairly level area. ri e only a few len of f et tlbove either place. foCleary lie on tb outwa h plain which pour cl down Wildcat reek from the vicioi t. of ummit ( or Hillgl'Dve). The pre nee of catter d grnnite pebble among the ub anguhu ba ult cobble wbi h over the lo1v divide pro1•c a. former conn ction beh een the Wildcat aod l\Iock heba.li train. and, together with a terrace 30 feet high ju t ea. t of ine nod oth · terrace near urumit Lake prove the present lock hebali trnin to have been originally aggraded to a level higher than it now po. . e , B etween l\Ialone and Elma it i probable that commingling of gravels from the Gate and l\Iock hehali. train occurred; but the Gate tra-in her lo tit fodividuality, aud in two or th1·ee miJes below fa.lon e the am el largely lie too high to po ibly come into the Gate train profll . significant terrac lies two mile ea·t of Elma on the high way along the north id of the river. It· tlltitw]e i 80 feet, higher than the large loqua.Jlum train entering o..t Elma and higher than the Moel. he]111li train ""here it i e at l\falone. Inclined tra.ta shown in it sections djp con isteotly westward. Thi. re ove the po ibrnty of the teri-ace being a portion of a form r fan-like pr adin of the oquallmn tmin which ente1·s the hehali j t below it. It i confidently referre to outwa h through the lock bebali ·, befor tl1e filling of that valley wa eroded by later glacial drainage to its pre ent dim n ion , It thu corroborate the eyidenc of the terraces at and Rbove ine. TnE CLo ALL M VALLEY Tn.,w . The foU1·th vnJle train to enter the Chehaii River valley i that of the Cloquallum, near the mouth of which Elma i itua d. Thi i compo ed of b o li tioct uniting t1·ain ; one from ummit, or Hillgo e in the valley of Wildcat reek the oth r cL ·cending the Clo- qu JJum prop r. The iJdcat .member pJ'Obabl the lar.,.c.r, i the econ I train to the we t 1 hich wa poured aero the Bia k Hills the grnve1 floor a ceoding w1th a con taut] iocrea ing gradient oorthwru·d to imp on col a definite notch at the valley Glaciati THE AT OP V..u.LEY T1u.1i;. The outwa h Ul the Matlock P ~;i.thwa. .i largely cover d ,\~ith fore t. It po e e but fe, prairie , none of them cornpar11ble in e.'I': cnt wi h tho e on the outwa h of th~ ca tern l be. Th altitude of tl l ·oute is known only approximately fro1 l . w·ve of the logging l'aiJ wa · both Iatlock nd loquallmn being given as 400 fe t above tide. Th width of the plain in the broa.d gap i probably qual to that at Gate about eight or nine mile though the fore t and the wa e of logging where the heavy grO\vth ha been remand have prevented mor than a reconnai a.nee of the region. 5fl Bulletvn No. 8, H aa7ii1ngton, Gcalogical urvey The outwa h plain imd moraine of the Matlock Pathway are drained by several a tern branche of the Sat op River, and by Cloquallun1 reek. The 1vest fork of the atsop never re ceived ou wash from the Puget ound Glacier. The valley train heading in thi outwa h uea and extending down the Satsop and thence down the hehali , i the longest of all the e.xtra-morainic train of tbe a hon Glacier of uget ound. It also originally lay higher above present all y bot tom than any other and further, ha been more largely de stro ed by post-glacial erosion. Its lowe t level con titutes a terrace reachlng from a point two miles above the junction of the Satsop with the hehali Valley, to Monte o.no, a di tance of seven miles- At l\:lo11te ano terrace of fre h glacial gravel with stream bedding dipping we tward lie at 40 and 66 feet above tide. In the north part of the city is a terrace lflO feet in altitude, in hlch well without exception find fre h gra el beneath a few feet of yellow oil. Though no pits exi t in this terrace to show- the material, there can be little doubt that its gravel is of Vashon age. There i no higher fre h gravel in the hehalis Valley below Gate. Half way between Montesano and .Aberdeen the highway for about two mile traverses a terrace surface well above the valley bottom, one mile of it being 80-85 feet above tide. It topography practically unbro1cen by ravine , is indicative of youth. ections show tJ1e material to be typical Va hon glacial ou.twas]1, with many fre :h granite pebbles. The stream bedding records a westward current at the time of deposition. ome ex posure show a peculiar mingling of stained and un taioed g1·avel trata or ma.sse of stained lll6-terial alternating with fresh granite-bearing gra el. The staining is :irregular and never very dark. It may perhaps be due to local infiltration of the fine 1·edclish alluvium which cover the tei:i-ace top, and po - ibly to the incorporation of older Plei tocene red gravel which underlie thi terrRce. The be t re :idence di trfot of the ci y of Aberdeen is ituated n a gravel terrace whose ummit is SO-S6 feet above sea le,,el. Glaciation of the Puget owntl Region 53 The gra el i perfe tly fre b and un tllined m ome ctions, hut near the ba e o! the bill -lope 11gaiu ·t which the terrace lies i material is red lik an old gravel lbough the tnining i not o deep or uniform. Granite peobl tue not common bnt can be found and are firm and unw nth r d. The beddin i hori z ntal w-itl1 r w trata clippin we ward. The pebl le are noticeably small ·r than in grav 1 n ar r the morain . n the hill slop abo,1e the terrace coD iderable tr t grad ing ha revealed man· tream-worn p bbl in the r idual earth, and ain d by it to it own hue. lid and creep eem o have interru e any continuity which ma have e ·i tcd orig inall but a con iderable b d lie bu. 1 of the old hi h school building, ea t of tl1e ravine back o{ th t. Ro e ademy. It i 90-95 feet abo,·e tide. ome pebbl in it are f irly £re h, but mo t of the mnterial i w-eath red. The e biah gravel terrace along the lower heltali , in pince actually overlooking tide wo.te •, can mean u one thing; no.mely that th o.t op valley train where .it enter th he- htllj Valley ho. degraded far elow its ori ina.l le el. The e terrace mu t be remnant indicating the level to which he ,,a.Ile wa oD e filled. They ugge t that high terrnce rr ponding ilh he e urvi-ving -portion of a former deep filling hould e foun up th nt p towa.r the ! fotl k out- a h plain uni th have een r m ved by ero i n. The a - op Valley boul 110, be examin d. For the lo er portion of the • at. op Valley, th re 1tre few gl ci l gravel, ahov the pre ent fl d plain. Tl1e low t ter race urfac . which .tends d°'' )fonte a.no mny fol low d up the atsop f r wo mile . In one place a mnll t ri·o.ce ri e ti.bout !5 f t above 1t. n the a t ide of th lream, a lender tena •e f fre h grn.v l Ii nl no the valley lope for 11. mile and n hnlf. Between the .i unction of the ea t and we t fork of the a op. he road whi h r llow the ea t fork n cends to hafer' rairie who e al itud i about 180 feet 11 o e tide. rrhi i compo e of luciul g1·av 1 u i not hin>h noul'Ph to be 54 Bu,llctin No. 8 W a.Ahvngton Geological urvey con-elated with the high terrace at Monte ano, or \\ritb any ter ra e we t of tlmt place. The bluff \ hich border ho.fer Prairie on the we tis reall a ridg par,ttllcl to the edge of the prai1·ie. Beyond it ere t there i a mall tream valley beyond which ti ere i still higher laud. The ridge appear to be stream-formed though lying parallel to the adjacent prai.rie. It altitude i 90 feet above the pl'airie or ~920 feet aho tide, and it bow, fre h glacial gravel on both lope and ere t. imihn· grnvel occui·s a1 o on the a c •nt to tl1e higJm· land be oncl but d e not reach above .220 feet in ~ltitudc. Tbouah the de cribed 1·idge parallel to the prairie which lies in the at op alley i omewhnt unusual and .not to be con idered a terrace it appears to have be~n left b the ero ion of a former plain, aggra.ded by glacial gm el to the lev 1 of it ere t. The pre ence of th gmvel i the vitall important fact. It here lie high enough to allow· u de cen of 11 feet to the rnilc to the highe t terrnc at fonte ano, and a continu ation of a imilar grade down the heh11li . will touch the 0- 5 foot tel'l'ace betwe n fontesano and berdeen and the S0-35 foot tunace at berdeen. From the outwa h gravel about Mat lock, there i a de cent of 15 feet per mjle to tl1is high gravel overlooking hafer Prairie. The outwa. h plain about fot lock i probably contemporaneou with the lower ]eve] of the at op train and earlier filling about Matlock co1Telati e with the higb gra el above Shafer' Prairie ha probabl been de troyed in produ tion of the lower 1 vel . Th g ·adient of 15 feet per mile shon1d therefore be indefin.itely in reas d. Thu with one exception the whole e.rie fall into a con i t ent trenm prnfiJe from the moraine regiou to tli ca the grade becomfog more gentle und the material more fine witl1 incrt'as ing di tance from th moraint. The cxc pti011 noted i the high gruvel at Aberdeen, 90-95 feet above tide. N otlling more than J.ender hypothesis can be advanced for the occu Tei1c of thi g.rav 1, and ince its pre ence is not helieved to affect con- 4 -S+ony Po int Chot1nel \ ~ 1 s-Ter:ial~uat "'Pra'1r'1e . \ / / \ ,, 6-Terminal M or~ .,...... - _ /.. \ 1 sooND GLACIER-- ~ . / 1 J:: lN'n Loli, rui:,•t 'ouncl GI Arrows ln clusions on our present problem, it i not further con idered here. When it is con idered that the western lobe of the Puget ound lacier advanced to within 15 mile of the Ohe.hali Val ley where it stood 400 feet above tide a reu on (or the orio-inal great development of the atsop Valley train i apparent. Thi train probably 1·eacbed the Chehali Valley before tho e enter ing at Ima and Malone since the fatlock route wa. doubtle much Im er at the clo e of tl,e inte.r(J'lacial epoch of ero ion and perhap wa a th1·ough valley from Puget ound to the Che h li . maxjmum development, the Satsop , alley train must have effe tivel dammed the hehali , alley nbove the point of entrance. The ab ence of higher errace of glacial gravel in the Clo quallum Valley i taken to mean tbat it train did not extend to the hehali at the time of the at op train maximum de- elopment. Had it done o trenching would have re ulted when the Sat op train do.m wa removed, and terrace ivould be pre - ent.. ub equent loweri11g of the surface of the Satsop train y less heavily laden water • brought the outwa h dam down o that the loquallum train could extend out to and down the Cl1ehali . There wa no ubsequent lowering of the Cloquallum train pre umably b cau e glacinl water did not co11tinue to u e the vall much afte1· the time of maximum d :po-ition. Terrace in the Mock hehalis gravel both within the creek 'Valley and out in the widei· Chehalis Valley lll'e thought to ha.Ye been cau ed by a imilar damming of the Chehali at Elma by the loquallum train. Lowering of this banier by the glacial Chehuli permitted the lower levels of the Mock Chehalis train to form. A con iderable sand terrace lies against the north ide of the valley betw en Elma and Satsop. I altitude i r ecorded a 90 fe t abo e tide with con iderable chance for error becau e of barometric changes. It is higher than the gravel of the Clo quallum train between Elma and Sat op. ince tratified sand is ahno t never found in the outwn h depo it of the Puget W.\l Fto. 1. Large l1llermound Area on :.!Ima Prairie. F10. 2. Typical Mounds on Mirna Prairie. For('gruund o. portion o! Plntc ,~11 I. S11nrlng dl•v,•lopment of Jntrrmouud 1whtilc11. Glaciation of the Puget ou,nd Regicm, 57 ound Glo.cie1·, ome pecial conditions pre umably operated to produce tbi terrace. It i here noted b cau e a po ible cau e may have been a lackened current or ponded water pro duced 1, the atsop trttin dam in the Cbehali Valle . The an:u:uit of the prominent flat-topped pur of old red gravel in the ea tern angle between the at op and Chehalis valleys ha an lcva ion of 180 feet above tide and it udace gradually a cencl nor hward along the at op. It. i lower thaa th le,•els o.f Ule re As a on.sequence of the e fact01·s the glacial gra,•el of the hehal.i Valley ar of great value. Hunched of pit have b e11 opened in them from mere road ide excavation to the ambitiou xploitation of the Ford P rai1·ie pit covering everal hundred acres, which i owned jointly by the rego11-Wa hington Rail- 11>ad and aviga.Lion ompany and the }1j1.ago :Iilwauk e and Puget ound Railway. The glacial gro. el have thu uff red a secondary di tribution by mun into linear pattern of diver e chu.mctcr. In the citie of Aberdeen and Hoqu:iam th y ha e been di Lribut d in 1·ectangular pattern over t:h residual red cla of the region; on the country road-, the radiate in general from the riYcJ· · in the Black Hills they have entered 'edar r ek a tie bnlfo t of a logging raihvay, whe.1· the gla ier jllilt f ilcd of pouring th tbxough ~ a valley h·ain from the uo rth, and on the railroad they have been di po eel in long rib bon aero mile of countr where the on e exi t cl re po - glacial erosion removed tbem, and o e1· di"id into region whither th y could l1a e been arried onl by man. VA HO GLACIATIO AND THE COWLITZ Y.ALLEY. 1nnmAL LAKE ,AP. A noted in the opeuinO' paragrap1t of thi • chapter there are two pa e into the m litz Ri er \ al le from the north through which dnuna.g from Pug ma have entered at the time of ma~rimum O'laciation. the e i the va]ley lying between l\Iount Rainier and the Huckle- b rry !\fountain gl'oup. Th Tacoma Ea tero Railway u c it to r ach the "Big Bottom couutr of the Q\1 litz making this agJ"icultul'nl region tributary to a Puget ound cit . Tl,e ulle north of the pu i occupied by 'i\lincl'lll 'reek tributary to the i qually the valley outh of th pu . i occupied hy Tilton River, tributary to the 'owlitz. Tb cxi tenc f i\Iin- eni.l Lu.k in the valley ugo-e t gla ial occupo.boo an~l a plau ible h po he i in ab cnce of field tucly would be that Puget ound ofaciation wa re pon ibl for it xi tenc . Ex amination of the i quail. Valley between • aton ille and Pii.rk__. Junction bows a definite southern limit to the Puget ound ice at LeGrande, a ta ed in the preceding chap er. The r i - Glaciati01i of the Pi,gct , ound Region, 59 qua.Uy Valley for a few mile above that place po se e e1·y few trace of form r glaciation. The ame i true of tb valley of Iinei al reek a far up a the la.kc. Iineral Lake lie in a v Be tributary to 1\lineru] '1·e k, do.mm d by a moraine , bicb cro e th mn.joT vall al o. Grru:tite i abundant in i but doe not exhil it th wide range of character ho\\•n by th gran itic bowlder of the Puget ouml drift. Thi moraine witL other till depo its -f artlier outh, i to be refen d to glncie1· from ]\fount Rainier. The col between l\Iinero.] r ek and Til ton River i 1660 feet o.bo e tid . It i il broad drift-fill d val- 1 but it wa doubUc s clo ed by 1\lotmt Raini i.ce long be fore the Puget ound Glacier crowd cl up on the north lope of the Bald Hill , in a po ition wher it migbt conceivably have cnt a valley train over to the Cowlitz. Further the altitude of the col i about 4 0 feet above the higbes Pu.get ound drift about LeGrande o that even if the i qua)] ValJey up to Park Junction and the 1\linerul l' e.k-Tilton River val le had been open it i doubtful if dl'ainage woul l ha c flowed a.cro . NAPAVINE DITlDi::. The lowest place in th dh,ide b tween the behali and owlitz River lie in the nxi of the great ·tructural vall y of which the Puget ound 1·egion i a pottion. The village of Tapavine 444 feet above tide li near it. 10\ve t point and 11 mile outh of 'entrufa1, wher the ou wa h rnvel which enteT d tlle kookw:n buck reach d the. 'heh.alis. At .en tralin he e grnvel lie 1 8 feet above tide and eon titute th ,•alJe fillin on which the city i built. But the .h nrdl T a h beyond th city limi and uo txn e of Puget ound g ravel ]1as be n found . outh of tlu place ·u,'I'! whru·e man has obviou I. tran ported it. The divide lies about !50 feet higher and, uJmo t without further on idcnition might be dismi ~ eel 11. R po ibJe rout for glacial outwa h from Pug ound. Railroad cu aero - it give po itive e"idence that only a deep re idunl ojl occupie. th divide. i;:w.Au:s: r Rn'En o'L. \ grellt ou wa b filfo,g oc upie he 'owlitz Rinr ,•all b low lo Rock. In the vici11ity of 60 Bulletin No. 8, Washington Geological ur ·ey Ethel it is several miles wide, and well 150 feet deep fail to penetrate through it. It con titute an almo t flat divide be tween Lacamas 1·eek and ewaukum River, and its gravels were carried down the latter toward the Cbehali . Thu we find that no outwa h from Puget Sound glaciation ever crossed to the Cowlitz Valley, but on the contxary, drain age from the outh ide of Mount Rainier actually invaded the p1·ovince of the Puget Sound Glacier. CH.APTER IV. VASHON RECESSIONAL MORAINES AND ATTEND ANT OUTWASH . SYNOl'SIS. REGION OF Fn.oNTAL l\i!oRAn."Es. RECESSIONAL 1\iollA.U,"ES .AND OuTWASR OF THE EASTERN Lo:nE. INTRODUCTORY. TEN-ALQUAT AND Roc:KY PRAIRIE OuTWASH. THE lNTERL011ATE l\ifoRAINE, AND DnAINAGE UNDER ITS CoN Tll.OL. REcEss10NA.L FEATi:-m,s OF PlEllcE CouNTY. lNTu-Mon.,o.n.1:c 0UTWASH OP THE WESTEllN Lo11E. Mo.&AINEs NonTH OF THE CASCADE 1\fouNTAIN SPun o.F TRE PUGET SOUND BASIN. WHATCOM COUNTY i\foR.AINES. SAN J UA;--. CotrnTY MollAINEs. REGfON OF FRONTAL MORAINES. The great relief of much of the Puget Sound basin was un favorable to the development of distinct moraine ridges. As a consequence, they are well developed only ( 1) on the upland plains between the Sound and the Chehalis Valley, and about Matlock, and(~) on the lower plains in Wbatcom County, near .Bellingham. Their complete absence elsewhere seems to indi cate that there were no long pauses as the edge of the ice re treated northward. The absence of frontal moraines was noted by Willis in 1897. RECESSIONAL MORAINES A.ND OUTWA.SH OF THEJ EASTERN LOBE. INTRODUCTORY. For the successful delineation of the sys tematic relations of moraine ridges, a forested country is about the last place to choose. Since much of the Puget Sound region possessing these moraines is densely wooded, the data. herewith presented, and the correlations suggested, are to be considered as the result of reconnaissance only. 6fl Bulietin No. 8, Washington Geological ur ey Ex.cept the Bellingham area., the reces · onal moraine lie o clo e to the terminal moraine of Puget ound that they might almost be con idered a part of that mora,ine belt. But change of ome magnitude in the d1·ainage during the early stages of retreat and in the outline of the glacier mar[J'm, are thought to ju tif the u e. of the term 'rec sional. The belt of rece ional moraine .tend from nettr Ort.ing and apow in on the ea t to Little Rock on the we , lying tluougb~on the Puget Sound drift plain. It one great feature i au interlobate moraine the mo t ma ive moru.iue of Puget ound, which records the re olution of the ea tern glacial lobe into two during retreat. lntra-morninic outwash p1ain and drainage channels offer the be t data with which to work in any attempt to re olve the 1· oes ional moraine ridge of Puget ound into a equent.ial scheme. They have been relied on entii·ely in the pre ent chapter. When the glacier wa at it maximum four different routes carried e ca.ping water from its ea tern lobe to he hehali River; the Stony Poin channel the outlet of a mall glacial lake just south of l\lclnto h the Tenino-Bucoda Toute, and the Gate P athway. The tony Point channel so named from Stony Point chooThou e where thi va11e train enter the Skookuo, hue k, rece.i ved dl drainage from the en tire glacial margin ea ·t of it at maximum advance, and remained in u e during the early stag of retreat. The glacial lake outlet and the Tenino-Bucoda route oon cea~ d to carry glacial \tater, while the Gale Pathway 1·emained a drain g line 11. long a the glacier kept th ba in clo ed north of U1e lympic Mountain . (See Plate XXUT for areal distributioJ1 of moraine· and out wa h.) 'I'ENALQ AT AND RocK PRAnttE O TWA H. Tcnalquat Prai rie j ' a gravel plateau seve1·a.l quru:c mil in extent, ]ying north of the villag of Rainier. Its udace i di po ed in great ter races running ea t and we t, the eries d c nding northward. In generl;ll, the urface of each terrace ha a we h ·ard lope. The highest and large t plane urface of the prlliri desceod Fro -L la outhwestward. The fac of the teep de c nt b t n the t nace are in ome pla cl n cut ero ion carp· and in others definite ice contact lope. . The ea tern margin of th prairie like he northern de ·end by b1·oad terrace whi h at· parated by i contact or e.i·o i n I p . Tenalquat. P1•ail'ic i mpo ed of horizontrul grav L, good ection · { , hi h are expo ed in cut 1 ng the hi lfilwnukee iind ru t ound Railway w of (dnier where the depth of uch m~lerial i at lea ·t 50 r t. The prairie ren.che a maximum altitude of abou 510 feet oea.1· the northea tern µorti n of it highc t plane urface. Thi wide tract of unforc t d countr overlap all adjacent land. The floor of the glncial drainage chann J n which Rainier is built Ii t the foo of an abrupt lop de ccnding 70 feet or more to tJ1e ooth and outhwe t. The de c ding ea em and northco. tern lope from thi high plane are covered with till and tl1e tlorn i characteri tic of till. urther the pre ence of bow]d r up to e eral fe t in diamet r on the lope t make it oleo.r that the front of the aJac-ier r t d a.go.inst them while the grn 1 pl in o the outh wa a ga·ad d. .Mo rainic urfaces to the north and ea t lie about 75 feet lower than the highest plane f the prairie. Tenalquat Pi-airie, thu bounded on the north an F10. 1. Mounds on the Northern Portion of Mirna Prairie. FJC. 2. Kettle among Mounds, Mirna Prairie. A r~w ra1n1-1r deveto1wd mounrt,; IIP on slope$ and h•>ttom. Glaciation of the P,uget S<>und .Region 65 the Rainier channel and by the po t-glacial ero ion of the Des Chutes River. That the oricrinnJ gravel filling between Tenalquat Prairie and the tony Point channel did not posse s a gradient of 50 feet to the mile i hown by the lope of the highe t level of the prairie, whlch probably does not ex eed 20 feet to the mile. If tony Point channel recci,,ed drninage from Tenal quat Prairie the pre-ent low col could not have existed at the time. " ... t ' ' ", ' ' ' ' ' ' ,, 2' ',.. ' ", ' ~;-', ' ', ' '\,, ' ' ' :B '' D ' , North Soullll F1a. 11. Dlagrll.Dlmatlc r0S11-seet1on ut Tenlllguo.t PrDJrlc. A. Pl11tean po,:otlon. Wa.tl!rs ilowlng southward tu tony rolnt bannel. Glaolu front at 1. B. Terraces ot ortbem Slope. We.tera Oowtng westward to Rocky EroJrle (toward obsl!rver). Glacier tcont at 2 Wbll.C 10111vrnulll terrace obov B, llDd tee-contact slope lcom B to C, wece .formed. 0. Margtnol Dro.l.naga CllaJlnc1 !or lee at 3, dlschargt westward to llocl.-y Pre.Jr!e. D. Moraine. The ice front immediately we t of Tenalquat Prairie reached its maximum po ition a. mile outh of 1\Iclnto h on the rock hill of that region 650 feet above tide. The ,,alley of l ar Lake at McIntosh was expo ed by ice r treat onl after the highest 1evels of Tenalquat ra.irie bad been nggraded ruJd after the tony Point clumnel hnd been ]O\ ered by the ero ion of les heav ily laden water . The altitude of the col at the w tend of thi valJe i but littl above 350 feet and tl)e T nino Valle 1 a westward e-0ntinuation of the same axial line. But the abund ant outwa h gravels about Tenino were :not ca.n-ied through the Clear Lake valley. No evidence i known that glacial -3 66 Bulletin~ o. 8, Washi1tgton Geological 1irvey waters ever u ed thi valley a a drainage route. It altitude appear to have been ju t enough higher than that of the Stony Point channel to keep it free from the invading gravels. ot until the glacier had withdrawn from the northern lope of the moraine which is banked up on rock bills from McIntosh to Tenfoo, did glacial drainage ab1mdon the Stony Point channel. The lower route then expo ed led we tward across Rocky Prairie and through the foytown channel to Rutledge and Mjma prairies 011th of Little Rock, there cro ing the mo raine and ntering the Cbeho.li Valley a few mile farther south. ( ee flg. 4.) Glacial drainage from the east, cros ing the outhern and lower portion of the plain, oon cut a channel that eparat d the Tennlquat Prairie gravel from the head of tony Point channel (flg. 4). To th' later drainage cour e b long the out wa h plains of mith Prairie Ruth Prairie and the channel floor on vhich the town of Rainier tand . T errace rt e above the ea ·tern end of Rocky Prairie. South of Lake O.ff ut they are 285 feet above tide on the north ern flank of the moraine 15-~0 feet above the adjacent prairie level. Rocky Prairie thus wa aggraded to a high T leve1 by early glacial drainage and eroded by later drainage at its head to the depth indicated. Many outwa h area of the Puget ouud lacier 1· cord the . ame glacial hi tory of early maximum depo ition and sub equent removal of a portion of the depo it. u h ha ahead been no ed for the outwa h about Tenjno and on the Mock beha.lis and atsop valley train . It will be em to be true al o of Tenalqaat Prairie, Mirna Prairie and other outwash area . The mjnor tran -morainic channel a mile and a half ea t of Tenino (fig. 8) had no part in the hi tor of the Rocky Prairie ontwa b. It i a narrow valley without gruvel tenace with a wampy 6oor and with its col 335 feet above ea le el. Thi altitude how that d1·ainage from Tunalquat Prairie Glaciatio-n of tho Puget ownd R~gion 67 never used this 1·oute which obviously wa of but local un porta.nce. By the titt1e tha 1' treat of the ice had opened Rocky Prairie a a drainage TOute, the front of the glacier had with dra,vn from the nortl1ern carp of 'I'ennlquat Pra:irie plateau and drainage which i u d from it retreating edge built the ucce ive terraces that characterize the northern part of Teoalquat Pi-airie. Each terrace i genetic11.ll a broad valley floor, po e sing but the outhcm wan the ice having formed it n rthern side. ( e fig. 5.) 'l'he eries, de cending in order towa.rd th north i to be correlated probably with the terraces of Ro ky Prairie. There i a lope of nearly 50 feet to the mile between the first terrace on the northern descent from the Tenalquat plateau and the highe t terrace of Rocky Prairie to the we t. A on the south Jde of the plateau so on the west, the later work of glacial and po tg]acia] drninage bas jsolated Tenalquat Prairie from the gravels which lie farther down the former cour es of drrunage. We t from Rock Prairie, glacial waters conv rged into an inegular channel among moraine hills leading to Rutledge and Mima prairie and con titllting the drainage route here described a the Maytown channel. [This i hown on Plate XXIIl and fig. 4.J Locally a at Maytown, mall pro.fries wt on tbe outwash gravel in tbe channel, though swamp and fore t cover much of thi drainag cour e. The Mn ~town channel i n 1\1 drained b Beaver Creek which enter Black Ri er at Little Rock. THE bTERLOB TE Moll.AINE, AND DRAIN GE UNDER JTS CoNTllOL, 1·0.gments of rece sionaJ moraine lie north of Rocky Prairie and W a Irick Prairie and probably indicate po itions of the glacial margin while the drainage , a following the cours mentioned above. orth of Tenalquat Prairie, the morainic urface gradually becom s more pronounced until it reaches a maximum altitude of ~00 feet abo,,e the pla1D in a great spur of morain.ic bill projecting northward bet\veen Lake t. lair and the i qually Rjver. The material of the e 68 B1tlleti11 No. 8 TF ashington Gco1ogical urvey hill till. Erratic bowlder of granite are common and lakele bog n.nd w1drn.ined depres ·ion an1ong hort choppy bill characteriz the topography. o outc1·op~ of bed rock are koO\vn by r id nt of the region who nre fa.mili r with th e hill . Tbi northward proj ction of the moraine, graphically hown on accompanyjng .map (Plate XXIl nnd XXIII and fig. 6) re 'Ord a considerable indentation in tbe "'Inc.ial mti.rgin in which depo ition took pl ce from the ice on both ide , form· ing the inte.rlobate moraine. A long n the glacier lay again t thi hi"'h moraine depo it which j tbe rrtat t produced by the Puget Sound Va hon Glacier, glacial drainage from the ea t wa forced to pa south of T enalqutit Prai1·ie and acros Rocky .Prairie to the Maytown channel. 'When the ice retreat d from thi spur a low r pa ,vn opened around jt nor hern e.nd for the water coming from the glacier mugin and from local drainage east of thi point. The Rainier channel alricks rairie and tbe east end of Rock-y Prairie were abu11d ned o.nd a new gravel plain •a buj]t, lying long the a tern flank of the high mora.tru area. ec fig. 6. The portion of thi plain which j now t.l'eeJe , i known n 1: elm Prairie. The water Bow d to"·a.l'd the no1·thwe t and aggn.ded a pfain who e lope i not more than 15 f eet to t.he mile. The altitude a th northern angle of the in.terlobate hill i al.>out !70 feet above the ea. The cour e of the current after rounding thi • pw.· wa ou th ward for a f w mile turn.mg west a.gain near the outbern part of the Wm. White donation claim, and ontinuiug thence to the pn~ent cour e of the De hut River. During tl1e et1-rli r period of this drainage a gra, 1 plain wa built along t11e route de cribed to the no.r-thern end of Rocky Prairi . The northern nd of Rocl---y P1·airje is too high bowcvcr o allow corr lation with the !Z70·foot terrace uortl, of the moraine hill near Lake t. lair and mu t be con idered as a depo·it of wate1· dir ctly from he ice. Later u e of th.i drainage route from Y lm Prairie and Lake St. lair, developed a definite channel from the prairie land oc- Glaciation of tlie Puget , ownd Region 69 cupied b the m. bite donation claim, lo tbe course of the De Chute . ~ drainage from he Puget ound Glaci r ea t of tJij channel and £ro1 Iouot Raini~ (except the owlitz River) flowed in the clean ut old river bed no, occu ied b' pu 1·geon reek. ( ee fig. 6.) Anothrr northward projecting moraiaic ar a exist we t of Rocky Prairie and in a way imilar to that alread de cribed, the gla ial drainage Imm it lowe t route north of the hill . On the wet ide f thi econd moraine pur th wn.ter pread out a road, fiat gri:w 1 plain in the vi inity of outh n1on . Between thi place n.nd Little Rock the ountry i 1 r I and e...xcept wl1ere ditched, · co\'er d with \'ll.mp. It i doubtle an ouh a ]1 plA.io of xc ptional flatne , and is probably com posed of material finer han the pr vaiLing gr1wel. The hig1, moraiuic hills lying OOTth f T eo11lqu t Prairie, which controll d th formation of Yelm Praisie and the depo i tion of ou~wa h outh of Lake t. 'lair nre i.nterlobtite in ri"'in. The 1•idll'e which compo e th~m in their northern an mo 1phatically morainja portion lie parruJel to tl1e two id of the acute angle which the moraine mn form . The , atcr h.ich flow cl oortlnvard along ~ elm Prairie directly tow rd the iee front m t ome ob tacle which doe not no"' ex:i t. namely. the glacier it If, and turn d i hack t the outh for t1nee or foul' mil to the purgcon reek course, wh ·eas l wer urfnce at pre ent lie farUier aol'th. T\vo morain.ie hiU · lie on the north side of this outhward loop and doubtle mark th, po·ition of the ice front when it hnd fir t vithdrnwn from the i11terlobate depo it. Thl'l·c i tliffi ult in mapping morn.ine and out,rn h are in the northern pa.rt of Thur ton ou11t . Reli ,f of the moruinic tract i Ji ht in mo t pl1we. and they ma ' b ar but a thin out- a h grav l cov r and yet be eff ctnally concealed unlc·· es.ca ,•ation reveal their rue nature. Kettle cannot be taken n~ cri eria for di tingui hing b tween moraine and ou wa. h b cau e th . al'e commou in l\l'Cll. , of deep outwa h g1·avels. Both topog raphy and oil ma fail to di tingui h the two type and, how- F10. 0. Glac1n.1 D r..,.nK' I!!! rr,;,01 UI E 11Mcrn Lob<> r b An·ow6 llldlC::e d('I~ Prairie. c ru t ound Glaclcr during Ult> LulldJ ta ngo co11rece ol tbla etage. D Glaciation of the Puget Sownd Region 71 ever the pre ent mappin"' may delineate th re pective area , it i probable that sue eeding tuden of the rec,ion will disagree with it. RECE SION L FE TUn.E IN P:mn :& o ;NTY, Ea t of th i qua.lly River ]jtt]e record ha been found of varied and changing condition during glacial retreat from the terminal moraine. Much of the region i heavily forested, and road aero it are few. On the whole, the 1·eg.ion between McKenna which i '1 miles east of Rainier and the Ohop Valley ma, be characterized a ground moraine and an area outh of McKenna and west oI the i qually River al o pos e t.hi character. The Ohop Valley and Yelm Prall'ie alone ghre data on which to ba e conclu ions regarding the po ition of the ice fron . These will be con idered pre entl_ . Morainic elevation ju t we t of Eatonville ri e 150 feet above the outwa b on which tlte town i . ituated. They are ituated with longer diameter a.st and we and 11.re pl'Obably of rece ional moraine character. Theil- pa.rallelisrn with the outhe.rn drift bound~t"J and entire indill'erencc to the much nearer eastern mar,,.in of the Puget S0ur1d drift which lie at o. right an le to their cour e indicate that the Puget ound Glacier , a not wa ting on it ea ern margin in a wa at all comparab1 with t11 r ~treat of its outhern edge. The e ele,ation near EtitonviUe con ti ute the onl known reces ional moraine deposits in thi part of the countr . From here north ward and norlhwe tward the ountry i apparently a uniform plain of til1 here nd there inci ed b minor glacial drainage Jin , . The region i t-ravcr ed from r1orth to outh io it central part by th fount Rainier highway . .Anotlm· good road between McKenna and Eatonville allows exrunination of the reaion. To the north, and at a lower altitude, lie the c,reat teilo. oom out wash plain of Pierce ounty ituated northea t of all outwash thtt far de cribed in U1i paper. A cent from the teilncoom plain mo t of which are prairie, to the densely fore ted till/" plain i in many place over definite mo1·ainic ridge who e orientation parallel lbe lin of contact between graYe1 and till. 72 B1illeti!n No. 8, Washington Geological Survey An a ce11t of 200 feet i made in one mile on the Mount Rainier highway over mora-inic country on the northern margin of the till plain. outh of Muck and three miles we t of the Mount Rainier highway harp, morainic ridge· exi t, bearing mall ks.me-like hiU of gravel on their southern lopes. Again, be- ween Ro and Mc1Cenna a eries of at lea t three till ridges lies ea t of the Chicago Milwaukee and Puget ound Railway, trt!nd ing W. Their trend i out of harmony with evidence from the outwa h a to the po ition of the edge of the ice on thi area, a will be hown a little later. The till plain ea. t of McKenna on the Eatonville road is abundantly strewn with angular granite bowld · . R cent road grading ha left them freshly exposed in a region where a heavy growth of lichen and mo ordinarily effectually conceal the character of roadside bowlders. A few cut in the con truction of the road bow the characteristic Vashon till of the Puget ound Glacier. To 11nderstand the correlation here attempted between mo raines and outwash of thi region, and the ame of that portion of Thur ton County already de crib d lying west of the i - qua.lly River, a bit of gl1tcial Jake history mu ·t be con ider d. From Orting northward the Puyallup River flmv in one of the troughs of the int rglo.cia.Uy erod d topograph which a hon glaciation failed to obliterate. Being a. northward trending valley it held a marginal lake while the glacier withdrew along its length. Thi lake, named from the river now flowing in the tl'Ough, fir t had it outlet into the Ohop alley, which then ca.rried the di charge from the White, Carbon and Pu allup river in adrutioo . But mo t of the western margin of the Pu allup trnugh :i lower than the col in the Ohop alle outb of Lake Kapow in, and to hold the lake and the river named lo this cour e the ice edge mu t have lain o. far outh as Orting. ( ee fig. '1.) ow the altitude of the hop \ alley floor where cro ed by the Mount Rainier road near Eatonville, 465 feet, allows a de cent 0£ a.bout 10 feet to the mjle from thi cro ing to the l'J..\ 11-. \' Fw. o ·ky Pra!rl lound will! lntermou:nd bble. , ·a hon tt•rml,rnl mornlnl' In t l, ~ (11•t1tn~,·. Fm. 2. Ro l,y Prah'I Mottnd . Smull mouodle • 1m •t Rt lhL• 1,,fL Glaciation of tlic P·11,get o•umd Regio1i '13 lowe t terrace of the glacial i qually at ~IcKCJma. Thi ter race li too low to be orr lated with the 270-foot ten·ace on the noril1cl"11 pu1· of the interlobatc moraine, and hence i younger than the purgeon reek hanne1 it elf youn er than all other outwo. h feature of Thor ton om1 y thu far de scribed. It tliu ma be concluded with ome degree of confidence that the Pug t ound Glacier hugged the northern flank of 1\:Iount Rainier 11ot retrea ing 11orth of Orting until the mo ra.inic lake region of Thur:ton ount wa ei·po ed b the re treat of the ice. ha.mber Prairie, ju oath of the e lake , is thought to have carried the drainage of thi time we t to Du h Prairje and the l31ack .River cJ1annel. The corr lative of Y 1m Prairie i found fo i qually Prairie on the a t ide of the Ni qually River. The river vall y be tween the c two prairie i younger than the depo ition of tb gravel and is con equent on the northward lope of a once con tinuous outwa h plain. TJ1e ero. ion of thi valley ha divided the original plain into two longitudinal portions, cons-ti uting 1 - quo.Uy and e1m pt·ai1·ie re pe tivel . From the grade of the out,va h gravels on both ide of th interlobate pur west of the river the ice front -i kno, n to ha e po se sed an acute re-entrant angle in thi part of the ea t ern lobe. Per i. tence of thi an 1e a the front of the glacier retreated i indicated b phenomena of isqually Prairie de scribed in the following paragraph. Along tl1e northeastern side of this prairie sharp ere ted hill of Va hon till ri e in three or four group above the gravel plains. They eparate isqually Prairie rrom the broad teila coom gl'a.vel plains farther northea t. Through the gap be tween the e group outwa ·h gravel appear to have been poured laterall onto i qually Prairie who e descent · to ward the nortb,ve t, at right- angles to the direction of this tributary flow. Only , ith ice well removed from the lake country of Thur ton County, could glacial drainage on is qunlly Prairie flow so fur toward the northwest· and only with l"/4 Bulletin No. 8, Wasltvngton Geological Survey the ice front resting on or directly behi11d thi linear seri of moraine hill , could glacial dninage have been poured simul tan ou y from the gaps among them onto i qually P1·ai-rie. nle error has been made in ob ervation, the conclu ion is valid that there i h re reco1·d d the eastern id of the re-entrant angle which developed early in the retreat of the larger lobe of the Puget Sound Glacier. In Pierce County, further ret1·eatal tag of the gl.acie1· are poorly record d. The great predominance of outwa h gl'avel on the teilacoom Plain outh of Tacoma, i the trik ing featur of the topography. Since the are uninterrupted by morainic eminence , it hn. not b eo po ible iJ1 thi tudy to di.ff erentiate them in the manner which ha been attempted for the outwa h of Thur ton County. Their northem portion will, however, be di cu sed in connection with the glacial lake hi tory, m which the ar a played an important part. L.'ffRA•MOR~C OUTW ASH OF THE WESTERN LOBE. The difficulty of examination of the region occupied by this lobe ha been noted in the chapter on t.be terminal moraine. In four traver es between tidewater of Puget Sbund and this moraine covering about all the route of travel ~ hich exi t in the region no rece ional moraines have been found. Outwasb plain back of the moraine of the we te.rn lobe are identical in almost all detail with outw11 b of the ca tern lobe. There i the a.me clean well-rounded gravel of perfect1y f:re h appearance in ection , and he ame topoo-raphic di po ition in terraces with low gradient of the plane urface . Thc~e plain , unlike the plains of the ea tern lobe ore fore ted but the fore t i thin, It con ist of a cattered tand of fu- with the fore t flool' entirely free from bu he or oung tree in many place . From an agricultural view point the country is n arly hopele . The.re i no inhab'tant for 11 mile along the road between 1at lock and helton and for 16 miles no stream is cxo ed by the road. Ba.snit bill ri e above the ground moraine and outwa h about U1e headwate1·. of heJton and Gold borough creek and com- Glaciation of the Puget Sownd Regio'll, 75 plet ly enclo e Go ncll-.Mill and Little kookum creek outh and outhwc t of helton. They may be con idered a a low northern portion of the Black Hill . Th west m lobe of the glacjer d:i charged its drainage into the at op and loquallwn valley aero a ummit altitude of approximate] 40 feet, while drainage from the ea te.rn lobe cro cd the t rminnl more.in on a floor no higher than 175 feet at tl1e Leginuinr:, o:F retreat. It i ther Io1·e to e expected that when the ice of the r -entrant angle about the Black Hills with drew to an a.ltj tnde below about 850 feet, the lowe t glacuil chru1~ ncl 1..'I!o,vn aero th Matlock Pathway dive1· ion of the drainage of the we tern lobe from the at op to the Gate alley train would follow. But the hill aboYe d ci·ibed beneath the ice at thi re-entrant a11gl off ' 1" d uc e ively po ed barrier , so that not unb1 the interglacial valley of helton Creek was ice tree did the diver ion re ult. And because the open valley of helton Creek became an arm of Lake Ru ell a oon a cleared of ice aTI oubrn b gravel carried oulhward by the hifted current came to re t in a "'rent delta who. e lakewa1·d face con titu e the northern alley bluff nt belton. About 15 mile of tandino- , at r in Lake Ru ell intervened between the helton delta and Black River channel by which drll.lnage of the we tern lobe reached the Chehnli at Gate. By the time th.i diver ion occurred the whole hi tory of the eastern lobe review d in this chapter had b n on ummated. and the su ceeding hi tor of the glacial lak ,ms being enacted. The tardy reces ion of the we tern lobe of the ice may find ex planation in it more northern lo a.lion and it omewba.t higher altitude. It i nl o to be noted that the region of the we tel"n lobe re eive at pre ent about 30 inches more rain annually than the region o,,ered b tl1e ea tern lobe. If a. similar greater pr ipitation prevailed dm·ing he V n hon glaciation llnd callle in the form of now it hould have effectively retarded retreat of he western lobe. In adj u tment to the new and lower level only tho e intra morainic gra"el plaius lying between the kokomish River and 76 Bulletin No. 8 Tf'asliington Geological Survey helton re k lvere altered. A per istent terrace carp along he road from Seo t Prairie, northwe t of helton, to the kokomi h River i attributed to such adju t:ment by glacial drni.rtage from the he d of Hood anal to helton. The carp p es e feature "·hich no ice-contact lope or delta face could ht~ve, and lack character the hould po e . Terrace carp de cenc3ing ea hvard, are cro ed between cott Prairie and Lake rahwatiel, and are thought to be attributable to the same cau e. The later change on the gravel plain between the kokorni h River and helton belong properly to the history oi the glacial Jake , nnd will be di cussed und · that ubj ect. MORAINES NORTH OF THE CASCADE MOUNTAIN SPUR OF THE PUGE'.l' S0U1'.'1J BASIN. Tm;: WHA'l'COM OUN'l'Y MonAlNE . The plain region of Whatcom County lies we t of U1e Ca cade and north of the pur of mountainous hill which were described in the introduc tion as interrupting the Puget Sound ba in. It is included jn the Blaine and Suma quadrangle of the . Geological u1· v y and it topography is almost entirely determined by round moraine and b the post-Cl'lacial alluvial depo it of the ooksak River, A fe, areas exist where the glacial till ha been left in true frontal moraine 11.dge , among the fir t to be built in the retr at of the Puget ound Glacier after those of Pierce and Thur ton counties. moraine ridge begin outhea t of Ferndale and e:\--tends northca twru·d for five miles pa ing ju outh of Luurel. An o her moraine ridge lie immediately ea t of thi . tber mo nuruc area. somewhat cattered, occur along the Bellingham Bay and Briti h Coluruhia Railroad near W a.bl and Go hen, and al o clo e to learllrook and uma . Yet other areas of imilar chara ·ter lie between ook ak and Getir chool (Darn- town). The Laurel moraine i the one oi most i.ntere t. It orie11ta tion afford a clue to the form of the Puget ound Glacier's front on witbdrawa.l from the mountainou iutenuption of the ba in. '!he moraine ground plan describe a curve with it Glaciatio1i of the P~1,get owul, Regfo,i 77 concavity to the north. The heav frontal moraine depo it on the ea tern face of the large interglacial hill , e t of 'erndale, together with the Laurel moraine, ghre a complete outline for thi portion of the front of the glacier. It indicate that the ice wa. moving a.}mo t directly from tl1e north when the de po '1t in question , ere formed. orroborative evidence for th.is conclu ion i ecurcd -from glacial grooving on the huckanut sandstone in Lh southern part of the ity of B lingham, the trend of which i magnetic north and outh. An element of doubt remain a to e:·act di rection of movement becau it could not be d termine whether the edges of out ropping trata , ere re pon ibl for the exact direction tuken. In general however, the ice. mu t have moved approx.irnatel south in production of the groovings. Another item of con iderable inter t attaching to the Laurel moraine i the -fact that marine hell occur in j . An i olated moraine hill two mile west and one mile outh of Laurel WllS opened om ear a.go under the impre ion that it wa a drift~ covered rock outcrop with the hope of finding coal which exi ts in the Tertiary edimentaries of the region. The tunnel which wa driven penetrated a tony hardpan o firm that no timbering wa reqnired. lam shells were reported a-s occurring in large numbers in this till. The writer picked up a few fragment of barnacle hell from the old dump of the tllllllel. Half a mj}e_ south of Laurel, a gravel pit has been opened in the same mornine. The ection thu ma e how abou tllree fe t of Vashon till at the top, ver like that near the urfa e in the mo t outhem depo it~ of the Puget ound Glaci r. Be low it is three f et of a tony clay different from the ov rlying till. It contains and and ravel, but ha no folintion like the overlying till. Instead it i cu by roughly vertical crudely conchoidal joint along which the cla · part on drying. The e urfu.ce are tained a dull ptupli h-brown b percolating water the clay el ewhere b ing gray. Beside their prew1ilmg ,erti ality, these joints al o 1·ndia.te to a minol' deO"ree in all direc- tion from he larger pebble. in the ma . ·harp line of con- 78 Bulletin No. 8, Washington Geological wrvey tact exists between tlie till and thi clay. In the clay were found a number of fragile marine h Us, ome with the valve still 11.ttached. Ben ath tJ1e hell-beari11g clay is stratified and, and beneath this in turn i the gravel for which the pit. wo. opened. The gravel is undoubt dly of a hon age. It shows fore e.t bed whicl1 ip towa.rd he outb and outhwe t. The upper urface of the e beds wa irregululy eroded by rwm.ing water before depo ition of tbe overlying and. All the e eviden e U1dicate that the moraine wa ubaer.ially depo ited, and the in.eluded marine hell of the peculiar clay apparently mu t be explained a having been plowed up by the glacier. The hell-bearing clay therefore is a till of peculiar f acie . Further discus ion of thi ubject will be found in hapter X in connection with data on sbell-bea:ring ground moraine of the region. TE'.E SA JuA.N CoUNTY Moll.AINE, The rocky an Juan Island group, constituting the count of the a.me name, lie in the .line of prolongation of the ascade Mountain pur 1vhicb is south of Bellingham. A a role, the drift deposit of the e islands are limlted to he valley . Grou11d moraine, however, con titute a large ptll't of Lopez I land and i pre ent on much of San Juan Island. But he only topographic features of con siderable relief which are composed of glacial drift, occur on an Juan I land. Cattle Point, the mo t outhea tern tip of San J aan Island, is an e.longat d penin ula trending a little outh of ea t. It bears a triple ere ted hill of drift near the end ri ing nearly 300 feet above t11e ea at its foot. Between the hill and the main part of the i land i a ridge of drift, le than half the height of the hill. The Cattle PoiDt hill {Pl XX, Fig. 2) is fore ted onJy on the northern lope and the ridge h completely treele s. The soil when the fore t ha failed to grow is gnvelly, a.nd bears the flora of the outwa h prairie south of the ound. On the northern lope borings w-ith oil aug r by l\,lr. Geo. B. Rigg of GlaciatiO'll of t/t.e P11,gct ownd Rcgfrm, 79 the Univer it of W a hington have hown the presence o1 a cla ey gravel or till beneath the forest hwnu.s. A eacliff along the outhern foot of the hill hows the ur face grovel to attain depth of iO to 50 feet. Belo"· it i a zone of intimately mingled till and gravel trata, U1e product of water escaping in the pre ence of glacial ice. a hon till of ypica.l facie appear beneath thi zone and in turn re t on trongly glaciated country rock, with groove as much a six inche deep. Plucking ha interrupted the grooves to ome extent. The gravelly outhern fa e of this great hill of Va hon rift i jnterpreted a having been origin.all a teep alluvial fan built on a frontal till ridge at the debouchure of a glacial tree.m. The gra el in the :,eacliff show an imperfect and variable outh wnrd dip, which i never a teep a the fore ct true ure of a delta. I is believed to be the original alluvial fan bedding. The till on the northern lope records the ice wall '1.ga..in t which the deposit wa banked. The ridge which connects the trifid hill with the ma.in part of the island constitutes the mo t perfect frontal moraine in the Puget Sound country. It outhern slope is an outwa h apron of more gentle de cent than that of the Cattle Point hill It bears many larg bowlder strewn over the urface. The north ern lope i teeper and i imilarly bowlder- trewn. This moraine ridgewa the ite of the American military camp during the years when Great Britain and the United tate held joint po e ion of the i lands. E cava.tion for the earth , orks thrown up in 1869 expo ed til1 which ha never subse quenUy become covered with vegetation. few miles north of the attle Point moraine and within a mile of the town of Friday Hal"bor i outh Rill almo t a replica of the Cattle Point bill except that it ha not the trifid ere t. It outhern lope is compo ed of treele prairie gravel, and it fore ted northern lope i composed of till. Till inti mately a ociated with the gravel i h wu in tt eacliff on it outhern lope. o moraine ridge i as ociated with it. a ~ ith 80 Bulleti1n No. 8, W r;ahingtO'n Geological Survey the Cattle Point hi1J and it i considered to record a b1·iefer pause of the retreating edge of the ice. The absence of fore t on the outhern lope of the e two hill ha.s been explained a due to the trong ind from the broad Strait of Juan de uca to which these slope are expo ed. The tree at the ere t are gnarled and wind-twisted, and the wind i cel'tainly of ome importance in the ecological problem -in ,,olved. It i here held, however that the difference in soil on the two lope i the hief cau e fol' the distribution of the fore t. The moraine ridge of Cattle Point, with a gravelly soil on_ both slope , i unfoTested, and the rock hill of the i lands are fore ted on all lope alike. The gravelly lope are tl'eeless for th.e ame l'ea on that the outwa. h plain outh of Puget ound are prairie. The an Juan I land e..xhibit many flue illu trations of striated rock urface . pace ca.nnot be given to a catalogue of them, and uch is not nece ary ince all known striae and grooves trend b tween true north and south and magnetic north and outh a range of 24°. The Cattle Point moraine lie at right angles to thi di:i:ection, a to be eKpected. The great glacier which overrode the e i land , overtopping even Mount on titution, 2,409 feet above tide, had a dominant southwud movement toward Puget ound, a. movement re col'ded alike on the broad top of Mount Con titution, and on the rock shore of the i land group. UL,,1,ETIX No. 8 Pr.ATJ!l VJ Fm. 1. Mounds of Rocky Prairie. ~oh• 11lon~<'rri or a pos•1hl.r h11·Alllng rores1. ~~Ill. 2. l\lounds or Rocky Prairie. CHAPTER V. THE MOUNDS OF THE VASHON OUTWASH. SYNOPSIS. CHAJlACTER OF THE REG.ON. NATUllE OF THE J\foUNDS. TY:PES oF MouNl>s. Tim MnrA TYPE l\Iom.:os. Fo1tM Al'tD SIZE. GROUPING, SPACING. COMPOSITION OF MouNl>s AND 1NTERMOU1''J> AREAS. STRUCTURE. TIIE Fon:o TYPE MouNDS. Four AND SIZE. GROUPING, SPACING. COMPOSITION OF MouNDs AND lNTERMOUND AREAS. STRUCTURE. TAlluLATED CoMP.AltISON oF CRAllACTEns OF THE Fon.n AND MIMA TYPE MouNDs. AREAL DISTRD3UTION OF TnE 1\fo-UNDS. DISTRIBUTION OF ~foUNDS WlTH RELATION TO PRAIRIES. DisTnmuTION oF MouNDs WITH RELATION TO MoRAINJ::s. DxsTRD3UTION OF l\fouNDS WITH REU.TION TO ALTITUDE OF PnAIIUEs. D1sTRJllUTION OF l\fouNDs WTT:e: RELATION TO Dlll'n:RENT AGES OF THE O u Tw ASH GRAVEL, DrsT:nlDuTtoN OF l\IouNDs WITH RELATION TO SLOPE OF PLAIN sURF ACES. AREAL INTER-RELATIONS OF THE Two MouND TYPES. SU1t0\1A1lY OF AREAL DISTRD3UTI0N OF TH.E MOUNDS. HYPOTXESES. T:a:E Mnu TYPE. CONDITIONS CONTROLLING CONSTRUCTION OF ACCEPTABLE WoRXING HYPOTHESES. HYPOTRESES PREVIOUSLY ADVANCED. WEAK1''ESS OF AllovE HYPOTHESES. Ln.rlTATIONS OF A SucoESSFUL HYPOTHESIS. THE FoB..D TYPE. LDnTATIONS OF A SUCCESSFUL HYPOTHESIS, 89a Bulletin "l\o. 8, Washimgtcm, Geological urvey CHARACTER OF THE REGTO . The Vashon drift of Puget Sound may be div.ided into two different ueas the northern portion being predominantly ground moraine and the outb rn part being characterized by outwash plain . These plain a.re largely prafries, because of the coar ene s and sterility of the oil. The latitude of Tacoma affords a convenient divi ion line between these two area . The outwash from the Va hon Glacier of Puget Sound di - charged into the hehali River by two main route , one on either side of the Black Hill . The Black Rill lie on the we t side of the axi of the tructural valley containing Puget Sound. They bear till on their northern :flank and are entirely mttounded by out-wash gravel. NATURE OF THE MOUNDS. The remarkable mounds which have often been referred to, cover large areas of the e gravelly outwa h plain . Their char acter, distribution and gene is are the subject of thi chapter. T"Fl'ES O'F MOUNDS. At the outset two types of these mounds a1·e to be distin gui bed. They will be termed the 1\l!ima type and the Ford type. Though a ca ual ob erver might fail to discriminate be tween them, they are believed to be distinct in origin. TH.E Mll1A TYPE .MOUNDS. Four AND S1ZE. Where be t developed, the open prame bearing mounds of this type ap ar lik a meadow dotted with haycocks. The mound have a mmetrical, flowing outline, appear.ing to the eye to be egment of phere • though their lower slopes blend into the adjacent ground with a surface con cave upward. They range in height from tho e o little a to be just preceptible to a maximum of seven or ejght feet, and in diameter from si....: to ev n feet to sixty feet or more. In any one locality there i a striking uoiformity in the size of these mounds. Almost none exceed the dimen ions prevalent in that locality, and few fall below. This is the te timony of the eye, Glacfotian of the Puget ownd Region 8S though if careful mea mements are made a number will be found failing to reach the avernge dimen ion which by rea on of in con picuou ne were not not d in a vi ual urvey. (Ulu trn.tions of the {ima type mound a.re pre ented on Plate Il to Vll.) They ure uniform in bape a well ns ize. There i common ly aI'l elongation o that one di meter exceed the other at right ang1es to it by a mall fraction. T,vo mound rests may be so clo ely placed that the bn.ses blend with only fl addle between di er ts. The longation,, when pre ent, does not conform to nny definite orientation. Gno PING, SPACI 'G. All ob erver agree that no orderl ar rangement of the mounds in ground plan can be detected. Plate VIlI i a map of n area on .i.\limn Prafrie 400 by 500 feet, on .;,hich the mound have been care.fully located and measured. 'I'be lack of orderly grouping i apparent. In th matter of pacing the 1',.Iima type mounds are usually clo el set. There -i but rarely an intermo®d area, with a dia meter g1·eater than that of the larger mounds of the vicinity. An exception to thi tatement is found on certain pro..irie . The urface of Rocky Prairie in particular is affected by long sags ond well with a relief of cai-cely more than ten feet. The mound are almo without exception limited to the higher portions and from the e portion more like platforms tban 1.wells the descent i abr~pt to the bottom of the sag . CoMFOS1Tlo • OF Mo NDS .uro INTER"M'.O ND Anus. A con- tant feature of the gravel oubva h betning the mound is he pre ence of a black urficial silt. Thi ilt i present in many phice where no mound ~re developed but i never lacking in mound-bearing area . Road nnd railroad ections on everal different prairie how that the mounds are composed of a mixture of loo e gr vel and black ilt. Tl1e gravel below the mound is strati6 d and free from the blac"k ilt. The transi tion betwe the mound materfa.] ... nd the underlying clean gravel is harp. A gravel pit 40 feet deep, is being worked in Mi.ma Prairie by the Northern Pacific Railroad, in which cross sections of 84 Bulletvn No. 1V nshington Geological urvc y mounds nre con tantly bein made. The black ilt here ha a thi. lme of but a few inche between the mound . In the mound ections, howev r, the ilt i een to de cend lower than in the intermound space , giving, with th mound ·profile, a di tinct double convex len hape to the black . ilt aggregation as hmm in Plate II, fig. 1. The lower funjt of the ilt in the 1\Jima ections in many places ha broad, blunt, root-like downward projection eldom more than a foot in length. ' he e bend abrupUy heri? and there in the plane of the ection, or appear a patches of black silt in the gravel ju t below the mound , where the ection cro e their direction of bend. Roots of the herbaccou plants which grow on the mound are found practically a abundant at the lower margin of the ilt as cl ewhere in it, but they term inate abruptly in contact with the clean gravel below, e.~cept where eepage line occur. ample of the mingled gravel and ilt ompo ing the mounds on Mima Prnirie were WtJ.shed and the fine black materio.1 was thu removed. An. ordinary gravel and and like that immed iately b low the mound wa left. Practically all of the u - pended black material ettled in twenty-fom- hour . A ample of it wa ignited to determfoe the organic content. Almo t no lose of weight r ulted the material imply lo ing it dark color and becoming a fine gritty clay. The organic content thu i ve1· Ill.all. Black ilt unmingled with gravel or 11.nd taJ and Pla.le YI fig • 1 and fl). one were een with a maximum diameter of more than two feet. There i no hint of a closer pacing 01· piling up of the e boulder on the margin of t.he mounds than el ewhere~ uch a would ocei.n· if they had been dis tributed evenly at the out et o,•er the whole area and had sin e gravitated to the iotermound pace. . .At the we end of the pran:ie, mounds of pronounced development w-ith abundant intermound cobble , lie with a harp line of eparation adjacent to lower mounds on a lower surface and with no cobble6 what e-ve.1· among them. Among the e lower mound i an area 200 feet long and 20 feet wide elongated ea t and , e. t wl1ich. ha no hint of mound but i overed with cobble , (PL VI fig. !) . It i on thi. prairie al o that the be t development of sag and platform i found. In many cu e the cobble cease as abrupt ly on the upper edge of the platform a-s do the mound here and there overlying the brink, but showing no tendency to move down nnd accumulate at the foot of the lope. umerou road and railroad section on thi. prairie ho, the mounds tl1em elves to contain no cobble or bowlder . Other prairie show thi intermound cobble accumulation in varying frength of development. In place the tones are very few, and only large pebble in size. This i the case over much of Mirna prairie and here deep ection bow the entire g1·avc] bed to be lacking in cobble and bowlder , while a ell in Rock Prairie how the underlying clean gravel to po sess mru1y large tone , comparable in size to tho e in the intermound area . On Wah·icks Prairie railroad ections e-...Jubit the truct w·e of a mound-bearing portion 'With bowlder- re, n intermound pac . The bowlders or cobbles here ar seen in the ection to continue from one ide of n mound 01 n plane dire tly beneath it and reappear in tl1 e inte1mound area on the oppo ite idc. TR TTI1J,E. l r o stni.tification or other structure I1a ever been oh ervcd in ection. of the l\Iima type mound.. (See Plate II fig. 1.) All ob erver wl10 ba. ve pu l>lish d on the u bj ect find thi. unre ervedly true. There i , bown in all section a loo ~ homoge.neou ma of small gravel mL... ed with bfo.ck silt. 6 Bulletin o. 8 Wa.sl,ington Geolog'ical un•eu Th 1·e do not eem to l, o. "'1' ater proportion of silt nenr the ndac of the moWld mn. thAn nt the ba e. In prairi I: eking the mound bu hiwing the urfi ial ilt depo it gravel bbl d not o ur di tributcd through the -iJt a th y do in the 111 unds. Tfl · }' OllD TYPE lllOTh"'D • FollM ~o tz:E:. Where a beautiiul ymroetr and uniformity cJmrncterize tbe Iima t rp mound tho e of the Ford typ are un ymmelrical and irregufo.r in form and ,~ariabl in izc. The large ·l ar a of the. e mound i. on edarville Prairi in the be hali Vall y. The urface of hi pntirie in oml' plac · i almo t tumuJtuou ly heap d w-ith the gra el pil · in other places it is nearly pl1.1.11e and in th r. it is disposed in 1 ng g 11 le l pe . ndo ed hollow ar common, drainage by eepo.g l, ing p r f t however. ircuhu 01· Lightly elliptical mound are not 'Omm n. The ma.>cimurn ran in altitude between mound top and adjacent depre. ion i a out !O feet. On r nd found Prairi , one Ford typ mound tand 25-3 feet ahove it ur rounding . Thi particulnr mound {Plate fig. 1) po - even peculiar aucer-like depre ion on it u1 mi ar ranged in a somewhat elongate group transver e to the len th of he medial broad rirlg of ~he pra.irie. With the nn.rrow rim a inter- aucer area th y over the ntire um, it. Th i1· av r a e diameter i ten fe n.nd 11.verage depth 12- in he . Each b 01· n small Bat mound in the centeT and thus con tilu e only a marginal circu1ar d pr _. ion hein nearly fill d in the c nter. obhl occur 1n th annular depte ion and also tr , the idc of thi ord mound. The e aucer with the mound in the center are triking] · imiltlr t tho e descri e in h i inity of Mu k. The general charncteT of the form of the ord type mound may be be de crib d ns e sentiaJl knmc-Jik I a tate men which cannot be mt~de on rning the Mirna t pe mound . ROCTl'lNG, PA r G. tr ha been found of any y - temo.tic di po ition ol th e mound or of the hollow among them. Glaciation of the Puget ownd Region 87 COM.PO ITIO,' OF Iou.•n AND lNTET!M ND REA . umer- ous excavation ho1V the ord type mound to be , l,olly of gravel. There i no more black ilt on their urfaces than on the intermouncl pace , and none enter jl\to the composition of the ma of he mound. No agO'rcgation of cobbles among the e motmd ha b en a erved. ST1WCTURE. In Ford Pi-a.irie belmv edarville cavations by the Ore-gon-Wa hington Rnilway and aviO'ation ompany for railroad balla t have afforded section of the mound of this type, comparable to the ection of the l\Jlima type mound in the l\lima pit. The male.rial is mainly b01·izonta.l]y bedded but i o erlain in one part of the pit by delta bedded gravel dipping westward down the valley the depth of U1ese beds not e...\".ceed ing 8 feet. Above the deJt·a,,,bed the tructure i confu ed, cur rent bedding -prevailing with no definite fore et or horizontal tratification. Thi extend to the top of the cut and at the time of the writer' examination included ections of several Ford type mounds. The beds in the. mound section in a few co.ses bowed ioreset structu:re, dipping toward the ce.nter. One such foreset strntum had grown from one side of the mound aero ll alm t to the oppo ite ide. TABULATED CO:M.l:'Al!.ISON OF THE CH.AR.ACTER Ol!' FORD A.ND MIM:A TYPE MO NDS. The following tabulation give the point of dislinclion be tween the t\vo mound type Above de cribctl: M.tMA TYPE ll'OllD TYPE Named from the perfection of Nam d from Ford Prairie wbl b development on the upper portion bas given sections that reveal the ot Mlma Prairie. origln of thfs type. 1. Symmetry of form. 1. Asymmetry of Corm. 2. Unllormlty of sl.ze In any one 2. Lack or u.nJtormlty of size. area. 3. Foreset bedding dipping to· 3. tructureless. ward center. 4. Black prairie sou to base. 4. No 1ncreased thickness of 6 Ma.x.lmum relief between i)rai rie soil. mound summits and ln 5. Maximum rellef between rmound areas, 7 fee . mound summits and lnte - 6. U11ually wlt.b. int8T.Dl.ou.nd cob mound areas SO reet. bles. 6. Never wUh lntermound cob 7. Closed depressions rare-. blea, 8. Unlrormity of distribution the 7. Closed depressions cofl]mon. rule. 8. No uniformity or d.JstrbtztlOD. 8 Bulletin 'l\'o. 8, Was71i11gton Gr.ologi al u1·vey AREAL DISTRIBUTfON OF THE MOUNDS. DISTn.fBUTto, OF THE MO ~"D W'JTH RELATIO~' TO l"RAillIES. There ar three cla e of prairie in the Pug t Sound coun try (1) tho c occuning on rock hill lope , where the oil doe not support a fore t growth, (~) tho e where the oil j. too wet for tree growth and (3) tho e on the glacial outwash. Our problem deal only with prair1e on gla.ciru gravcl . The outl ash gravel dealt with in thi, chapt r are of a hon age probably to be coucli1tcd ";th the Wi con -ju drift. They occur largely as outwa h plain with moraine or ice contact lope along theu· highest margin. ince a.ll di charg"mg water frorn Puget ound wa re eived by the wide Chehali Valley th gravel carri d farthe t. take the form of a valley train which d.i:ff er in no e ntial d tail from the outwa h plains. Fragmc:nt of the valley train between Gate and .Aberdeen which have esc11ped po tg1acial ero ion con itute prairie with all the feature of those of the gravel plain nearer the glaciated region. In all prairie of the outwa h grn el, vidence of flow ing water at the time of their formation i to be found (1) in terra e (~) in tJ1e bedding, where expo ed, or (8) imply in the general lope. 1n the map accompanying this bull tin, the a;1:eas of gla cial ouh a h are 'hown and the Ollter margin of the terminal moraine i indicated. The mound-bearing prairi are indicated on Plate X., ID. In ord r of development of he iima. type mounds, Miwa and Rocky Prairies lead all the other though each bn areas without mound . Wamck or Eaton Prairie follow in ord r with numerou but lower mound ·. Grand Mound Prairie po e a strongly accent d mound urface near the ea tern end, but the mound gradualJy become flatter we tward until they die ou in tbe vicinjty of Grflnd Mound. edarville Prairie po e e the best development of the Ford type mound . Gate or Baker Prajrie and Oakville Prairie follow. Ford Prairie Mirna Prairie and Grand Mound Prairie al o pos s a few mounds of thi type. Th prairie above noted are all loca.ted on the outwn h gravel w .ISHIS(lTOS Gt::lll,fllll('Ar, St r,n;Y Bt' LI.ETI ~ ::--11. rr TE n, FI . 1. Delta nl orn r or en a treet aud ixth Av nue, attl • 'l'h1• tlnrk ror,·•et 1Jed8 ,u·~ com110•1•1l or 11,;:ultr·. Fm. 2. Mound ut by HI hway, Mirna Prairie. Glaciaticm of the PU,gct ownd Regi01i 9 of the glacial lobe lyina ea t of the Black Hill re-entrant angle. 'fhe e co.ping water f-rom thi lobe com'erged at Gate into one valley, and produced a. all y train which reinforced b ucce - ion of outwn h from the \ e tern lob wa origina.11 continuous from Gate to Gra Harbor. Mound-bearing portion do not occur below !ah.me, e.t the mouth of tl1e Mock ,bebali , which i the first point of entrance of gravel from the \Ve tern lobe into the. Cheha.Jj '\ all y. The large t area of prairie oan ry lie uorthea. t of the isqually River the region being known in general n the Steilacoom Pl.a.ins. Imperfect Mirna type mounds are found here and there on tbi al'ea well within the limit of the tenninal moraine. On the outwa h from the western lobe, b t1Veen the Dla k Hill and the Jympic .Mow1tain. , prairie are le common in proportion to the extent of gr1.wel-covered m·face than ea t of th Black Hill . i\Iound are known in but one place. Thi i on Lost Lake Prtlll'ie, within the limit of the moraine. The mounds are low and incon picuou , and do not occur over the whole prairie. There can be little doubt however, tha~ these mound 1;1.re of the ame genesis R.s those o well developed on Mirna and Rocky Pwiri . DISTlUB TIO~ F MO U11.'D WlTB REL\ TlON TO .Mon 'E . In general distribution lhe mound-bearing prairie are a o ciated with depo it of the ea. tern and low r lobe of the glacier. Th Mima type a.ttain it ma..i,:imam deve1opment on Mi.ma Prafrie ju t out ide he t rminal mor ine and on Rocky P ra.irie, betw~ the terminal mor-aioe and n rece ional mo1·ainc; Grand Mound Prairie, fourth in order of development of 1\Iima type mound flanks the terminal moraine on its outer ide. n Mimn Prairie the mound may be tn1.ced up on the ba al lope of the lo\\' morainjc are which lies n01·th of tl1e prairie. In tlii position they are irTegu.lar in izc form and pacing, and are a ·ociated with a few ha.Uoiv kettle hole . One kettle (Pl. TI Fjg, ~) i 20 feet deep and UO feet in diameter and bears a few weakly developed mound n the ide and bottom. 90 Bulletitn ~ o, 8 Washington Geological. urvey On Grand Mound Pra.irje, in the place examined, they are lacking in proximity to tl1e moraine. On Rocky Prairi they exist within l •s than flOO feet of the front of tl1e rccc io®l moraine, uniform in ize, hape and pacing with tho e el e where on thi · prairio. .At thi cli tance from the moraine lopes, they terminate on the prairie surface a mound.Jes level zone of the indicated width margining the frontal edge of the morame. Wah·icks or Eaton Prairie lie ju t ea t of Rocky Prairie and, li.ke it, is bounded on the north and outh by the terminal and a rece ional moraine. Its mounds are Jow in relief. No relati-on between tbe proximity of the till ridge at the nortl1 and the ha.ra.cter of the mound wa e n. North of Offut Lake i a thinly fore t d country with small prairie area inter per eel 'rh topogntph 1. very much broken by kettle , but no moraini knob occur in the immediate vicinity the uea being apparently a pitted plain. 1ima. type mound are ommon on the level area. between the kettle but do not oc ·ur on the sid or bottom of the depre ion . drift surface bearing mound-like fonu , which hould be noted here, i to be found on the frontal or outhern slope of the most northern rido-e of the till area. outh. of Muck Po t Offi e. The mound here arc cattier d and irregular in form, both •ord u.nd Iimii type apparently being pl·e ent. About a dozen Mirna type inounds were een on the ou hern lope of the _ridge, which i heavily covered ·with outwa b gravel. TilJ expo ed beneath the gravel how the ridge to be of morainic origin. Ea.ch mound lies in a more. or le di tinct aucer shaped depres ion the rim of which i broken in most case and the depth of which was about equal to the height of tlte mound. The e mound-and- auc r arrangement do not occur on the teeper lope but lie at the foot. Cobble and mall bowider lie in the aucer surrounding the mound. The gravel outwa h here is iO f et or more in depth. The form de cribed are thus of outwa h dev Jopme:nt and not mora.inic in nature. The ea tern porti n of Grand Mound Prairie bear a median Glaciatfon of the Puget Bat high r area elongated ea t and we t in harmony with the longer diameter of the prairie and parallel to the moraine at the north. n it are the few Ford t pe mound po e sed by this prairie whil Iima type mounds arc di tributed every wl1e1•e exc pt along the pre ent floor of ca ter reek Valley aod the t eeper de cent to it. Mirna Prnirje i di po ed ia two level the higher being almost plane and abutting again t a moraine. A long pur of thls higher portion ru.n outhward a ross tl e lower lev 1 and bear the Ford t rpe mound of thi prairie. Mirna type mound are common on much of the lower urface. Both north and outb of the terminal moraine, the ruouads dimini h in degree of development though they extend farther beyond it tl1an back wi bin the gla iated area. ednrville Prairie ll! mile eyond the moraine ha the g1·eo.te t develop ment of Ford type mound of the region. DI TRID TlON OF 'MO .:OS WITH llELA TION TO ALl'lT DE OF PB.Alli.IE . An examination of the altitudt'l! of the mound-beariu and mouodl prairie of both lobe of the Puget ouud Glacier hows the Mirna type of mound on th higbe t Tenalquat Prai1·ie 500 f e t above tide and on one of the low t near Elma, 60 f et abo e t:ide. Grand Mound Prairie de c nd from fl"IO feet to 160 feet in ten mile , Md the !ima type mound Rre large t nnd b t developed at the head and lackii1a- at ti1e foot whHe on Rocky Prairie tl1e e motrnd are be t developed on the lower extcn od ab ent at the heAd. Ford type mound have their highe t known occurrence on rand i\Iound Prn.irie, !l80 feet above tide a11cl their lowe t 011 Ford Prairi ,. 60 feet above tide. Dl TllIB TJON OF MOU ']) WITH lU!:LATIO},,I TO J)Jl,'FE llENT G-E OF TRB OUTWA H CB. VEL, utwn h from the ic at the time of ma:xjmum ex.tent formed ce1·taio graYeU areas whfoh were abandoned by escaping water a oon a lbe ice retreated a mile or o from the terminal 9fl Bullefo, No. , TV ashitngto11 Geological Survey moraine and expo ed lower drainnge line . nc of the earliest outwa h o.1•ea to be abandoned wa the rrenino end of Grand 1\lound Prairie and the nille trnin which ~'t nd outh from Tenino to the Skookum huck at :Bucoda. The e gravel just we t of ' enino ar mound-bearing. Both type a.re well de veloped, though the • ord type mound - Ell'e f w in number. The black silt and in term und cobble of the 1'1ima type arc pre ent South of Bu oda tbe mound · di appeal" and none have be n !ow.id on the wjdc gtnvel plain about entralin. Di charging glacial water cea ed to flow th.rough the m r ginal drainage channel debouching at Tenino t the h nd of Grand Mound Prairie when th ice retr ated to a po ition north of Rock Prairie. ( e Fig. 4 ). D epo ition of outwa b gr v I therefor ceu d at th head of Grand Lound Prairie and at no ub equent time wa renewed. The mound near Tenino there fore lie on th olde t Va hon outwash. Durh1g the pau e 11.t t11e rece iona.1 moraine north of Wa1- rick and Ilo k Prairi , the grav l of the. e p1·ai.ri we.re de po i d. Th e caping water fl.ow d we. twn:rd nl DO' the rear of t]1e terminal moraine to iI.ima Prail'ie. everal mall prairie e.xi t along tbe route on of the e Rutledg Prairie bearing well de,·eloped i\fimo. t pe mound . Mirna Prairie therefore wa an area of ago-radation durrn"' the two pnu e of th i e front, and the moUJ1d of at lea lo"'er p rtion ar no older han tho or Walrick and Rocky Prairie de pite the ·tra moruinic po ition. Farth r back from the terminal mol"ain of the ea tern lobe than th prairie above di cw e there are bu four group of mound known to th wTi er and the are all of the .Gmtt type. The. :we rehdiv ly in ignificnnt, beina faint jneo-ular and cattering. o t Lak Prafri on th area ov red b the w t rn lob lie a few mile back of the limit attained bJ tl1e glaci.er. It mound are faintly developed and con titute the on] · known occunenoe of the e form on the outwa h from thi lobe. 'ro1u th above unr ·, i would appear tha ou1 outwe. b Glaciaticm of t71 Puget ou11d. Region 93 gravel immediatd a ociated with moraine de ·elopment are mound-bearing and that onl. outwo. h of early depo ition bear mormd . Thi. generA.lization i omewhat weak ned however, by the following data coneernin"' the 'hehalis Valle t l'tiin. be ea tern lobe of the 'a lion Glacier retr ated nortb of the latitude of Olympia, the trough of Puget ound became g1·11.dually uncovered, w,.d tandin.g water at the ice front re sult d. Exe pt on local divide and over the troughle area south ot Tacoma outwa h gro.veJ cea ed to he depos·ted. E - ca.ping water from Lake Ru ell• ponded in front of the ice, flowed do e along the ea tern foot of the Bl ck Hill to Gate ther entering the hchalis Yalle.. Thi water rehandled the drift over hich it flowed and carri d a con iderable quantity of graveJ into he hehali Valley. I eroded it outlet channel at lea t t.tO feet deep at the pre ent col. It appear t have eroded u wid channel on the ea t ide of 1\lima Prairie. The di charge of Lake u i,ell ontinued to flo tbrou.,.h this vall y; now occupied by Black Lake and Bio.ck River, and thence down the h hali until the -ice had re rented at lea a far north as ou]weather Bluff, between ood 1inal and Admiralt ln1et. omewhere north of thi h~adland the ice dam failed and the level of LaJ..-e Ru ell w11 lo111 er d to that of the ea. The out wa h gravel along the Bhl.ck- hehali drnint1.ge line tbu may have r ocived their uppenno t d po it at a time when the ice front wa many mile to the north in it final r treat. n alterna i,•e yfow i that the ii charge of Lake Ru ell eroded a channel in th hcl1alis ,,a.Ile train and did not pread over the whole urface. Let u now ·amine thj urface. - fima P1·ai1·ie i cli po ed in two great level eparated b. a more or le . abrupt lope de ·cending about 20 feet. 1\lound al'e be t d veloped on the upper level but occur in typical devel opment on the lope and on the lower level. Thi low r u.rfo.ce gradually de cend ea tward o the pre ent floodplain of Black Rivet· and bear mound so far down the lope that flood I ater • J. H. Bretz, ''Glacial Lakes or Puget Sound."' Jour. Geo!.. Vol. 18, No. 5, and chapter VI of this bulletin. 94 Bulletin No. 8, Waahingtcm, Geological Survey of the present river alma t reache them. Their occurrence here po sibly ma.y be a. oc-ie.ted with the operation of the Black Lake outl t of Lake Ru ell. At Gate, the prairie i mouud-bearing, the mound belong ing to the Ford type. cattered ord type mounds o cur on the highe1· area of the Oak ille Prairie. Cedu.rvllle Prairie po - esse splendid Ford type mound oi-er mo t of its surface. Ford Prairie has a few of thi type. Tlu·ee mile above Elma is ti low fragment of the ,,aUey train who e gravel probab] cam from the a tern lobe though below the point of entrance of the Mock hehali vaU train. It bears faint mound of the Mirna type, th lowe t and -mo t west n ocou1·.rence komvn. There i thu abundant ev.idence to sugge t that tlie ·auses of mound formation operated at a considerable distance from the edge of the ice, and perhap late in Va hon deglaciation. These mound of the heha.li valle tmin belong to be Ford type, there being but one oc urrence of weak llfima type mounds. The 11lte1mative view con ide1· that later di charging water through the Black~Ch hali drainage line did not occup the whol width. of the gravel-filled valley and hence mounds on the higher portions of the valley train may have been formed at tln early date. Po tglacial erosion ha removed o much of the Chehali vall y train that thi quc tion can hardl ue ettled atisfactorily. Dill•.rnmoTIO. O:F MO :1) WlTJl llLATlON TO LOP.E OF PLAIN nF E , Mo t of the fiat gravel plain of the region po se a gentle grade de ceuding in the direction U1e w1.1.ter -fl.01ved at the time of their depo ition. Here and he.re are teeper lope of the gravel occurring on the flanks of moraine ridge , on the lopes l:ietween terrace or on the id of kettle . Tu one direction the gravel plain may extend from an almo t lev I urfaoe up on low moraine flank the mound here In.ck.mg characteri tfo form and arrangement; in an oppo ite direction the plain may descend acros a terrace carp without notable cliange in the character of the mound . Glaciation of the Puget ound Region 95 In general mound on a moraine lope do not po ses char acteristic form and distribution. They are best developed on a gravel plain with a slope too gentle to be dete ted by the eye and they at·e rarely pre nt on th lope of kettle . A.REAL INTE1lr1lEJ. TIO.N OF THE TWO MO ']) TY-Pl':S, Mirna and Ford type mounds have not been found as ociated with each other in maximum areal development. Grand Mound and l\,lima prairie pos es a few Ford type mounds on the. higher portion of the. prairie urface surrounded b thou sand of tbe Mi.ma type mound . The rever e relation a fe.w Mirna type mound di tcibuted among many of the larger kind, has not been £ound. On both the above-named prairies Mirna type mounds lie undoubtedly up on the Banks of the Ford type, othiug h been een to sugae t superposition of the Ford type on mound of the Mima type. SmntARY OF ARli:AL DISTiilBUTION Oli" THE 11.{0UJ,.".D • (1) The mound- occur on outwu h grave1 from the ea tern and lower lobe of the Puget ound Glacier, only one occunence of faint l\,lima. type mound and none of the Ford t pe being known for the we tern Jobe. (2) The be t Mirna type development i found on prairies closely associated w-ith the terminal and ea1·lie t rece ional mo raines though faintly e eloped mounds of thi type are found on the hebali "'i alle. train far from the moraine . (S) Ford type molllld haYe been found alm.o t entirely on the Chehalis Va.Iley trajn a.nd adjoining ui;ra.-morainic outwash plains. ( 4) o significant relation ha been found between the altitude of the gravel plain and the occurrence of mound of' either type. (5) l\llima type mound are mo t typicaU developed on the earlier outwa h of Va hon age though large area of thi are moundle . The Ford type finds it best development on that portion of the Cbehali valley h·ain which entered by the 96 Bulletin No. 8 Washimgton Geological Swi-vey Gate Pathway. The question reginding its age ha been indicated. (6) Mirna type mounds attain their best development on nearly plane gravel urface , depre ed or ste ply loping area being commonly moundles . Ford type mounds, where scattered, occur on the higher prairie area i ol ted abote the urround ing surface. HYPOTHESES. Previou field work on the mound of Puget Sound glacial drift ha been limited to ha: ty examination of the chief prairies bearing the Mirna type. The Ford type mound have not been previou ly recognized. The Mi.ma type mounds are so striking in appearance, and o different from topographic forms ordi narily seen that e eo the car-window observ r i at once inter ested, and the range of hypothe e for their origin h.a.s been con iderable. '!:he study herewith pre ented will be justified if it ucceeds in showing the intricate nature of the problem, and in narrowing the range of hypothes . Di inction of the two mound types must be made, hence each wi)] be treated independ ently. THE MIMA TYl'E, CoNDITIONs CoNT.n.oLLING THE CoNsrn c-r10N o:F AocEPT Al3LE Won.JUNG HYPOTHE Es. Any working h pothesis for the origin of the e mounds to be of value mu t include recognition of the follo ing genera] facts : (1) The mound have a regularity of form that is remark able. In the hundreds of acres of the mound prairies there aTe but few exception to the general form of a spherical egment. (~) Mound in any one locality are nearly uniform in size. There are nowhere large mound cattered in an area of small mound though the couver e i tl'Ue in ome place . For any one region there i a maximum ize, above , hicb almo t none go and to which most attain. (S) There i almost invariab1 an accumulation of cobbles or pebbles on the urface among tl1e mounds, Where ection • l . 'I I .. Glaciation. of the P,ugct Sownd Region 97 are aftorded. stone of the ize of tho e in intermound areas .in ome places continue as a cobble ·tratum tlll'ough the mound them elve . In other plac where the intet·mound areas are cobb]e-bea1·ing no cobble are found hi the molllld ection . ( 4) All prairie of the region bear a urficial black silt. In the mound , the ilt ha accumulat d to a thickne a great as the mound height, and in place greater o that it form a Jen - haped accumulation, while b tween the mound the ilt i thin. ( 5) The mounds are be t developed on plane urface of ligh.t grade. They ne\ler occw· on urfaces other than those of glacial gravel. ( 6) The mound are structurele . HYPOTH.E ES PtLE\llOU LY .An ANCEO. ( ) ilke . The earliest discu ion of the Mirna type mound kno, n to the writer i that of Charles Wilkes in volume four of the Report of -the United State Exploring E pedition during the y ars 1888-184i. Wilkes twice cro d one of the mound prairies, probably Mirna, and on the econd trip be had thr e of the mounds e.....:ca 1,1.ted in the endea\lor to find relic of human agency which he conceived a 1·e pon ib1e for their origin. oth ing was found indicative of the 1i.vo.ge labor" of which he notes that they po sess the mark , ~cept a pavement of round tone at the ba e.'' He wa certain that they were not place of bux.ial and a inclined to attribute them to the Indian medicine men, though be found no tradition e..x.i ting among the Indians concerning their origin. (!e) Gibbs ( gas iz). In. the Journal of the American Geogl'aphical Society for 1873, George Gibbs describes a re onnai a.nee of the northwe tern boundary of the nited tnte in , hich he e.·amined a number of the mound p1•aicies of Puget Sound. On his return to t.he ea tern !:ate he de cribed the b"llcture and exhibited a sketch of the mound to Louis Aga iz who ' unhe itatingly pronounced them to be the nests of a pecie of ucker. Aga siz tated that 'this 6 b -4 98 Bulletin No. 8, Washington Geological urv y was nt that time con tructin.,. similru· mound in the ponds about Boston. Gibbs ace pt the lll..--planatitm noting that it 1.1,gree with the occur1·ence of 'la u trioe 1 terrace hich are com- monly as o iated with the prairies. (S) L eConte. In the a.me year Joseph LeConte pub lishe a hypothe is for the 01;gin of the e puzzling features, in the Proceeding of the alifornia Academy of cience. He con ceived bat the gravel and silt were ediment in the water of Puget ound, which he as umed to ba e on e covered the re gion. u ceeding the wi hdni.wa] of the ound waters, ero ion attacked the urface and r emoved the finer oil in certain 1uea . Vegetation encroa •hed at the same lime and obtained a foot hold m the higher region , holding them while the inter-areas were lowered. Increa ing dryness of lhe climate has caused the di appearance of this vegetation. (4) ewberry. In 18 4! John e1 berry pre ented a paper before. the i-ew o k Academy of c:ience on the origin of the fiords of Puget ouod. He frankly cottfe ed the mound to be ineYplicable. (5) Roger . The American Geologi t for Jttne, 1893, con tained an article by G. 0. Rogers on "Drift Mound near l.vm pia Washington.' Thi writer reviewed LeConte de cription and argument and objected to hi statements that the inter mound area contain linger pebbles than occur jn th mound LeConte having presented thi a evidence. of the ero ion of the finer material. Evidently Roger ex-amined tl1at portion of Mi.ma Prairie which i without cobbles among the mound while Le- ante may have een Rocky or Grand Mound Prairie where cobble di tribution is remarkably developed. Rogers s hypoth e i i that the gravel plain wa covered by a piedmont ice heet which on ablation, wa travei· ed by e caping drainage in 60 els so that tbe entire surface wa covered by wa hed debri . uch material on coming to re t tended to accumulate in heaps. Insol!Ltion cau ed the e bea.p to ink in the ice and liding of scattered material into the depre ion forth r tended to con- Glaciati011, of the Puget 8m1111d Region 99 centu.te the washed drift. Final melting of the tagnant ice depo itcd the heap as the pre ent mounds. (6) pham. In 1904 Warren Upham published in the American Geologist ome ha ty ob ervations from a reconnais- ance of a par of the Puget ound countr . e cros ed Mima a.nd Gnte or Baker prairie and concluded that the mounded 01-faces were correlative with the commonly hilly moraine belt of other drift area'.' rom personal o'hservntion of the e two prairie and from verbal de cripti011s of other prnirie of th region having mounds, he mapped th terminal moraine belt of Puget. ound a a broad curve convex outhward with the most extended portion reaching to Gate. (7) Other Explanation .• Conception of the origin of the mound more or le related to tho e pre ent d abo e, have emanated from ruany ourc . Mo tare valueles because based on no careful study of tht! region. Two lea.ding ideas ar those of plant or animal origin. One farmer who ha lived on Mima Prairie for a number of year i convinced that the mound which bear clump of the stunted oak common to the gravelly soil are increasing in height. Be tated that in leveling the mound for a. roadway the hor e plunged knee deep repeatedly in the gravel and ilt af te1· the sodded urface of the mound had been brolcen infening from thj that hollow exi ted where tree root had decayed. WEAKNESSES OF THE .A.DOVE HnoTHESEs. rom the pre- ceding de cription of the structure form, number, and distri bution of the mound and from the fact that no re.lie of human origin have ever been found in or 11. ociated ,1-ith them though hundred ltave been opened the hypothesi of human origin for any PW'P e whatever m t be abandoned. It is not held today by re ·ide.nb3 of the r gion though it i the mo t eductive of all explanations to the com.n1on mind. • M. R. Campbell discusses "Nature.1 Mounds'' 1n the Journal of Geology, VoJ. 14., No. 6. His study was devo~ed to mounds in. the valley of the Arkansas, ditferlng widely 1n compoaitlon, and l.n. char acter of the subsoil, l'rom those features found in the -PugeL Sound country. IDs conclusion ot animal ol'lgln can.not apply here. 100 Bulletin l\ o. 8, Washiington, Geological urvcy o ·one who ha been in the region a:nd een the splendid sweep of billowy topography over a thickly mounded prairie urface can give credence to the idea that fi h have heaped up tl1e Mi.ma type moUDds. It i obvioa ly mucb farther from the truth than the bypothe is of human origin. The prll.iries have never been submeraed in fresh water and probably only the lower ones were beneath the postglaoial ea water and that but for a hort time. !f.irna type mound al o occur on the plateau like summit of Tenalquat Prairie 500 feet above tide, untouched by any water but direct rainfall ince ces ation of the glacial outwash. The impos ibility of depo ition of the gravels in Puget Sound does not weaken Le onte idea. The objection which i fatal to hi conception i that the porou gravel so cffecti ely ab orb rainfall that hardly a trace of ero ion has been detected on any praixie, ave that of a few traver ing tream who e run off i largely ecured from other area . Consider ble tream flow on to ome of the e prairi from adjacent a,nd more impervi ous urfaces after heavy rain , and the water i o greedil ab sorbed by the gravel that the stream disappMr in a fraction of a mile. The pits in 1ima Prairie how "open work" gravel for a depth of SO- 0 feet below th surface oil In the lace of · evidence LeConte compari on with the mound pro duced by ero ion in ea tern Oregon is invalid. Roaer ' conception of the inter-action of glacier ice and escaping water fail to explain the mound of Grand Mound Prairie about Bucoda and ju t above Elma on the hehalis, o.11 of which lie beyond th t rnrinal moraine and ome of which were pe.rhap form d on the beh.ali "alle train during the last tage of glacial retreat from the Puget Sound basin. Fur ther the many ections in the outwa h prairie ba-ck 0£ the terminal moraine fail uniformly to record any re-advance of the ice over their urfaces after stream aggradation on them bad ceased and Roaei•s s hypothe i foil here a well. In view of thi la t point, and since the termino.1 moraine GlcLCiatio1~ of the Ptiget ownd Region 101 of lne Puget ound Glacier i a definite till ridge o.t one place two miles wide and !50 feet high flunked by the e outwa h prairies, Upham ha ty conclu ion e.nnot be on idered erj ously. In order to flt hi bypothe i thi w-riter ul o gues ed Lake Kapow in to lie in a keltle hole wl ich it does not, and mRpped the moraine a.s traver ing the Black Hill from Ga.t to Elma, all of which tretch i driftle , nnd ome of it l 500 feet or more above tide. Many other enor in the paper re ferred to make it almo t valuele . A pecies of large black ant, Formica sanguim.ea, inhabits the sparse fir forest growing in many places on the gravelly area of Puget ound outwa h and con truct 1,ill some five feet high. uch ant hills are built almo t entirely of bits of twig and pine needle . o ant hill could contain the pebble found in the mound . Jeither ant nor burrowing unimru could p1·0- duce the regula.rit of form and the uniformity of size in any one locality. The gravel trata. below tlie Ii.ma mound are undi tnrb d nod no burrow have e r exi ted beneath lhem in any way competent to account for the ma of the mound . That tree have grown on the Mirna mounds where none now exist is ugge. ted by th loo oe of the interior which allowed ho1·se to plunge to the knee in ilt and gravel b the o ca ional occurrence of . unlcen area a foot or o at:.ro on the e mound , and by the root-like forms in which the black ilt in place pene trate the underlying grn cl.. The mall unken area are o recent that the . od ha not healed over the margin.al cracks. To te. t thi bypothcsi mon carefull . an area wa sought where the oak and other fon:i t tree are growing on the mound . Such .II region was found on a part of Rocky Prairie. But no hint of tr e clump or groups ould b made out the di tdbu tion and thriftinc s of the tree not being rclnted in any way to the occurrence on mounds or intermound area . It j tated tnnt the Indian formerly bumed ove-r the e prai rie annuall and destroyed the tre growing on them. It i certain that today the fore t i encroa hing. In retracing sur veyor'· lines run 50 ears ago the limit of fore t growth n.re 102 Bulletin No. 8 Washmgton Geological Swrvey found to have advanced on the prairie .• The western pa.rt of Rocky Prairie bear many attei'ed mall fir . {Pl. VI, Fig. 1.) The e were found to po e from eight to ten annual ring at the ba e though ome were ten fe t high and some bardl ten inche . Evidently a wet ea on a few year ago allowed the eedling to end their root deep enough to urvive the drought of orclina:ry ummer . The older Te "dent all testify to the former greater ~-tent of the prairies. Many cruarled keleton of the broad- preading prairie oak ar found mouldering in a d n e growth of oung fir which ha killed them in the la t half c ntury. ( ee Pl. Fi . 1.) Though much prairie l,.md thu i being invaded by the fo1·est there are larg mound bearing area 1vhe1·e the dry oil probably never can upport tree growth and probably never ha . l.n.rrTA.TIONs OF Sue OE sFUL HnoTmm . ( l) The mound were formed at the time of depo ition of the gravel out wa b. Many fact already cited l d toward thi general con Ju ion. The ab ence of mound on the kettle lope and their pre ence b tween e kettle of the pitted plain north of Offut Lake u.nd tbe ntire lack of topographic cbange over the prairie urface ince glaciation ave rare trea.m inci ion , are the mo t definite fact upporting thi conclu ion. (!) The mound were formed only during the ]a t stages of outwa h action over u.ny one area. o trace of th i.r forma tion during depo ition of the tratified crra.vel on the grad uaUy aggrading plain in front of the ice now con tituting fima Prairie i hown in the orthern Pacific Railroad gravel pit. The section which hi pit afford :i half n. mile long and 30 feet :in mean depth and i dispo ed pa1:allel to the direction of flow of e ca.ping water. The rune conclu ion i drawn from the hicago, Milwaul ee n.nd Puget ound Raih-oad cut of the nme prairie dispo ed at right angle to the a ove direction. Wer the mounds formed at any earlier horizon. tructurele len es of gravel hould appear in the ection . • Com.mu:nlcatecl by Henry Landes, State Geologist of Washington. Glaciation of the Puget Sownd, Region 103 (3) The mounds are essentially con tructive forms. The evidence again t postglaciaJ ero ion of the gro."el plain has been presented above. The form of the mounds is trongly op posed to any conception of partial ero ion by glacial water, of previous depo it . In Plate VIII i hown one of the mo t definite cbannel-lik areas among the mound on Mi.ma Prairie. The impo siliility of channel origin. f r that area i at once ap parent from the map. The sags of Rocky Prairie might be accounted for by the a sumption of ero ion b e caping glacial water but he mound e,nd intermound cobble are found on the .intervening platform and are rarel ' in the ag . (4) The intermound obbles were probably not depo ited or aggregated b. the. agency which formed the mound. . It has ah·eady been explained that they have not gravita. ed to the in tennound areas from an original equable di tributian over the prairie urlace u equent to formatfon of the mound . T11e Wal:ri ks Prairi ection bow beyond an doubt that a portion of thl prairie urface wa uniformly cobble strewn and tl1at ub quent to tl1is the lima type mound were con- tructed on tru floor, bur ing the co ble eneath them, nnd leaving Hie portion in the intei·mound 1ll'ea till cobble trewn. Cobbles of the intcrmound type are not known t occur in the gravel nnd ilt of the mounds but a:re found in the stratified gravel immed· ely below tl em. Where the cobble are large, the gravel below contain large stones and where lie cob les are lacking or repre euted only by lsrge pebble the ubja ent gravel is deficient in fragments of cobble tone ize. The cobble on Grand Mound Prafrie decrease in ize to ac- ompllDy dec:rease in dirnen ion of tbe mound we tward. .But in the town of Tenfoo at the head of this oubva h area mound are not prevalent though the urface cobble are veritable bowlders and of great abundance. In order to ecure lawns, in the ea tern part of the town, the inhabitants di pose of tl1em by on tructing tone wall about their property. The ex:planation of t.lecrea e in ize of bowlder. nd cobbles w tward from Tenino i plamribly that of weakening current of e cap- 104 Bulletin No. 8, Washington Geological Survey ing glacial drainage. H does not follow that this proves their djstribution to have been contemporaneous with the formation of the mounds, !!ince the mounds may be due (a) to a re.han dling of the upper few feet of gravel, assort-ing the coarser from the finer and heaping tbe latter into the mounds, (b) to addi tional deposition to form the mounds after the cobble sti·ewn surface had been produced, as -well as ( c) to the pos ib)e forma tion at the lime when the upper few feet of gravel w-ere first deposited. (5) The origin of the black silt jg not believed to be inti mately related to that of the mounds. The black. silt seems best explained as being largely the clay and fine sand of the o.riginal unsorted drift, uot thoroughly removed from the gravel. In the l\1ima P rairie sections, beds of clay occur iuterstratified with the gravel and considerable clayey material may be seen on close examination on pebble surfaces and in interstices among the pebbles, though the "open work" effect is found practically throughout. T he black color appears to be a color only, the vegetal material imparting it being insign_ificant in amount in the silt. This same black silt bas been found on small level prairies of the Chehalis valley train as far down as l\fontesano, and on steeply sloping prairies of glacial outwasb as far nor th as the San Juan Islands, in ueitber place being accompa,nied by a sug gestion o-f mound topography. Tbe prairie vegetation and the ch-yness of the soil arc believed to be in some way intimately related to its occunence. T he subj cct affords an interesting ecological problem. The mounds a.re thus to be conside1·ed as composed virtually of a11 the constituents of till, save bowlders, and to be as lack ing in structure as till. There is a great difference, howeyer, in the appearance of the loosely aggregated mound materialf and the compact till of the adjacent moraine, beside that of color. The sharp demarkation between black silt and gravel at the base of the mounds is thought to be due to some local factors Bt"tL&TI'< X. run; IX Fu... l. 1' rd Trn lound n Grand Mound Pmlri . Fth. 2. B dding or ;\lima Pr:.llrie Outwn h ravel. Glaciation of the Puget ownd Region 105 controlling the prairie vegetation. Re ult of ucb factors are perhap expressed (a) in the abundllil.ce of mall plant root in the silt and gravel, and (b) their ab1·upt termination at the upper urface of the clean gnwel and po :ihly also (c) in the dow-m ard exten ion of black ilt beneatl1 ome of the molllld , re ulting in th double conv . · Jen form of the bin.ck oil in mound sections. (6) Agenci which might have operated under he limita tion ab ve enumerated are practicallJ 1hnited to i e and water, either of which may have been tanding or moving, or both. The time of operation wa during Va hon glacial reheat and de.po ition of the outwa h. urrent edding and delta bedding in the Mirna gravel pit how that water operated in both , ays during the aggradation of the gravel plain. If ice wa pre ent, :it obviou ly wa .in fragmentary ma se £ram the ad jacent glacier, 01· had formed on the surface of ta.nding water beyond the ice. If it operated ind namic pba e in con truction of the mounds it motion mu t have come from the energy oF flowing ,vateT or from e:xpan ion due to freezing ince no gln cia1 ice thru t could have occurred in many mound localitie > nor in mo t of them where adjacent to the moraine, ,vithout ha - ing left some indis_putnble record of its occttrrence. I may be ugge ted tentatively that if a l1eet of ice several fe t thick could be formed over the urface of an outwa h gravel plam and could ubsequently be flooded so that tream-carried debris ,vould be deposited on its surface it migh , on melting develop p-it into which the urficial dcbri would gravitate. in e water i densest at S9" F. the lower inter tices of the gravel in the pits of the p tulo.ted beet of ice would become filled with water at this temperatun?. Since uch water would be 7° warmer than the adjacent ice it would cause deepenjng and enlarging of the pit after the earthy accumulation had become o thick that Wlll'ming of the gravel by the sun cea ed to be a direct factor in formation of the pit . Sliding and wa,sh.ing of the urfac debri into these pit would expo e inter pit area and the melting of uch aFea would then proceed 106 Bulletin o. 8, Washington Geological Survey mot·e lmvly than when rock fragment trewed it and ab orbed the sun's heat. ome sucb et of conditions might gi e ri e, on final melting 0£ the ice to mound ; these being without structure without a ortment and uperpo ed on cunent-b dded gravels a are the Mirna type mound . Cobble tre,vin.g of the prairie ur faces i known at lea t locall to ha e ant dated the formation of the mound and require no place in the conception. The great range :in altitude and the wide pread di tribution of the l\firoa t pe mounds con titute a. eriou objection to tbi hypothe i . We might concei e of an ou:twa h plain becoming flooded with water and a beet of ice forming over the whole through ome ·ceptional and local combination of conditions but it is almost impossible to postulate the -repetition of uch an occurrence on every mound-bearing urface, e pecia.lly lopes. ~ - The explanation o-f the origin of the Mima type mound of Va hon outwa h of Puget ound gla iation i belie ed to lie in ome combination of water and ice action under the limitation impo ed above, uch effective combination being unique so far a the writer j aware. Detail of th:i ~---planation can prob ably go no farther until observation has detected the formation of imilar depo it :in ti e outwa h of ex:i ting piedmont glaciers or ice sheets. l"ORD TYPE. LIMITATION Ol!' A SuccEsSFUL HY'POTKESIS. A ati factory hypothesis for th gene is of the Ford type mounds mu t rec ognize-- (1) Their prevailing extra.-morainic position. (2) Their notable development on that part of the heha.li valley train which entered the valley at Gate. (S) Their great variabilit in size and form. (4) Their relation to adjacent Mima type mounded sm fa.ces. ( 5) Their compo ition, and (6) Their tructure. The hypothesis need not necessarily Glaciation of the Puget owuJ, Region 101 explain each item. but it must contain no incongruou element i.n their consideration. The compo ition and tructure of the e mound it m. (5) and (6) form the bas.i for the explanation to e adYanced. umerous e ti n how tl1at the e mound are compo ed entire ly of stream grav J . The ection of Ford Prairie have hown the tructuxe of th e gravel to be largely foreset, with the bed dipping toward the center of the mound from different sides. This delta structure i confu ed and impe1·fect the layers dip ping in diverse dire t-ion , ome bein"' uperpo ed on other with a. different dip. But every bed how- the original flow of the water which deposited th gravel to have been rougl1l cen tripetal with reference to the center of the mound. The onl sati factory explanation of the phenomenon of hum mock or mound compo ed largel of centripetally fore et gravel is that the mound ite were originally pool , and that water flowing into these pools and cauyi:ng tbe gravel which fill d them came from adj a ent uria e higher than the pre - ent hwumock ummi.t lying where the depre ions and inter mound area are situated now. From thi it eem that we must admit the pl' ence of ice block trand d on the ur:face of the delta- and tream-bedded gravel on whic11 the mound are built. deposition of tteam gravel ta.king place in the space among them. The soppo ed ic blocks may ha.ve b en derived from the Puget ound Glaciei· or th breaking up of lake or tream ice, and then transported down the glacial Chehali or they may have been marine floe ice drifted back up the Chehalis. All the evi dence favors glacial, tream or lake origin for the ice. Th practical limitation of Ford type mound to the Chebn.li vo Ile train item (~ , i ignifi ant. Limitation to that portion which received i upp)y through the Gate Pathway may be taken to show that the ice blocks were civer-bol'ne glacial berg ecause the greate t volume of e caping glaci 1 water pa sed through here and at Little Rock, but a few miles from Gate, the Va hon Glacier front reached its lowest altitude. 108 Bulletin No. 8, Washitngton, Geological Survey Tbe great variation in form and ize among the Fo1·d molllld , item (3) with the con equent production of undJ:ained hollow among them, and the la.ck of any orientation of hummock or hollows, are fact wholly consonant , ith the hypothesis ad vanced; indeed wholly corroborative of it. An extra-moraine po ition item (1), ugge t formation at the maximum of a hon glaciation though occunence in intra-morainic itua tion would not nece arily weaken the hypothesi . i\tlima type mound lie on the flank of the few Ford type mound of fima and Grand Mound prairies. This appear to show the ame r 1ation that i believed to obtain between the M:ima. type mound and their intetmound cobble · namely, that uh equent uperpo ition has placed the smaller ymmetrical mounds on the slopes of the older kame-like pile. The absence of the black ilt tluoughout the mass of the Ford type mounds and jts presence in the Mirna type mounds i har monious with the preceding vie,v . The Ford type mounds are composed of stream gravels, which would contain little or no ilt; the 1\1ima type mound , according to the explanation ten tatively held, hould po se a con iderable proportion of silty material. In both ca e , thi is the ob erved fact. If the black ilt has had the origin uggested, it should be found throughout the Mime. type mounds wruch have afforded a better oil than the "open work" gra els and not at a11 in mounds of the Ford type. This al o i borne out by ob er ation. CHAPTER VI. THE GLACIAL LAKE AND DRAI AGE CHANGES OF THE VA HO GLACIATIO YNOl'Sl.S. !.NTRODUCTION. GLACIAL LAKE Du1tING .AllvAl CE OF TKE VASHON PUGET SouND GLAcmn. GLACIAL LAKEs OF THE TIM:E OF :MA..UMUM V HON GLACIATION. 1\imon LAJrns OF THE BALD Hu.Ls. Gt. ClAL La.KE OF TKE DES HUTES Rrv-E& VALLEY. GLACIAL LAKE SouT:e: OF MclNTO H. LAKE BucODA. LAKE CHE.HALIB. LAJOss Oll' T.HE CHEHALIS VALLEY TRA.tN. w ADDELL CREEK LAKE. GLACIAL LAXES DU1lING RETitEAT OF THE VASHON PuGET SOUND GLACIER . EARLY- LAKE RussnL. BLACK LA.KE 0uTLET. S:a:EllLOCK DELTA, LAXE PuYALLUl', O:e:o.P CHANNEL. CLOVER CREEK CHA.IDolEL. LA.KE TACOMA. TACOMA DELTA. Sou:ra T co C11ANN.EL. C01in.ELATION OF TACOMA DELTA AND CHANNEL. AUllURN DELTA. KENNYDALE DE:LTA. ComtELATCON OF LAXES PUYALLUl", T COMA AND RussELL. STEILACOOM PLAINS. STEILACOOM DELTA. SEQUALICHEW DELTA. LAKE Nr QUALLY AND OnLJTERATION OF EA:RLY LAKE R ussELL. 110 Bulletin No. 8 Washim,gtcm Geological uroe-y GLACIAL LAKES ON OltTJD'!llN SLOPE OF TlIE BL C.li Hu.LS. L ATER L.urn RUSSELL AND THE HELTON DELTA. LAJrn KOXOMISH. LAKE Hoon. LIFTON O UTLET. BRINNON' DELTA. Pou-LSBO CHANNEL. L cJC O:F aoN D ELTAS OF OLYMPIC RIVER GLACIAL LAKE AlliMAMISR. FmsT STAGE. ECOND TAGE. THIRD T G, RirnMo m DELTA. LAKE SNOHOMJ:SH". HlsTOitY OF LATER LA.JtE Ru ELL, RJCaMOND DELTA. UO-FooT LEVEL OF LAKE Ru OIi.THEIi. LIMIT Oll' Lura R LACK OF V R O. D ELTAS OF KAME TERRACES. Dll.AINAGE MODIFICATION OF THE STILLAG AMlSH fuvEit. GLACIAL LAKE WHATCOM. INTRODUCTIO . The general topog aphic relation of the Puget Sound ba: in -closed on the east and we t by mountain ranges, at the outh by a low divide, and open to the north whence came the invading Cordillere.n ice-favored tl1e accumulation of tand.ing water in the basin wbile the ice front retreated northward. Be au e the last glaciation found a topography of strong relief in the Pu et Sound ba in and failed to obliterate it by er ion or deposition the opportunity for a lake hi tory of varied cha.racter during th epoch of Va hon glaciation was greatly increa ed. The lake hi tory may be subdivided into three periods, deter mined by the ad ance the maxi.mum and the retreat of the Vashon Puget onnd Glacier. Lakes of onJy the la t of the e divi ions of the Va hon epoch have left record of much impor tance. Little i known of lake of the advance of the Va hon Glacier. Tho e o! the maximum glaciation were but mall bodie LAKE PUYALLUP (Ohop Outlet) EARLY LAKE RUSSELL Clover Cr; tlet EARLY LAKE TACOM LAKE NISQUALLY LAKE.TACOMA LATER LA~E. RUSSE.LL lAKE SKOKOM I SH LAKE. HOOD GLACIAL LAKE SAMMAMISM (E.arl'I Outlets) LAl YorK Outlet F ihu"e of lhe ice drun a.nd enlran e of the ea.. F10. 7. Tl.me 11.Dd Space Relations or the Gtaclfli Lakes du.rlllg Vllllhon Retreat. 1U Bulletin No. 8, Wa~hington Geological uruey of water fringing the margin of the glacier where it closed the mouth of the arlier tream valleys. The retreat of tl1e Vashon Pug t ound Glacier permitted the formation of Lake Ru ell a water body occupying the alleys of PuO'et ound and di charging to the hehali River at Gate. The level of the lake throughout mo t of -it exi tence was 160 feet above present mean tide, perhap 1SO feet above ea level of that time. 'fbe lake wa lowered 40 feet by ero :ion of it outlet during the later tages of it history. During the early hi tor of Lake Ru ell the relrenting Puget Sound Glacier readvanced a few roile with an altered marginal outline nearly destroyed the ma ter lake, and fo ced the ponded water in the pre-Va hon alleys to di charge b a higher outlet. Thi gave origin t Lake i qually. The level of two contemporary tributary lakes, Puyallup and Tacoma, were not changed by thi rendvance. Sub equent retreat de troyed Lake Ni qually and allowed Lake Ru ell to re-fo rm Lake Puyallup and Tacoma early merging with it. o more o cillat.ion of the gla ier front are known to have occurred while Lake Ras ell lengthened northward to its ma.xi.mum e_·tent. On the west, tributary Lake kokomish and Hood were formed, and then de troyed by uncovering o-f lowe1· outlets during thi retreat; on the ea t, glacial Lttke ammo.mi h and Lake nohomi h were formed. The latter majntained an independent exi tenoe until failure of the ice dam eventually brought. the glacial Jake history of Puget ound to o. clo e. Figure '7 indicate the time relations of the glacial lake dur ing Va.. hon retreat. The pace relation are al o approxi mated if the top 0£ the diagram be considered a outh and the right and left side a. we t and east. The following ynop i correlate the more important events of the olaci.al lake hi tor during Vashon retreat. \\.\SI] I "rrn,; (>}'.ULOOlf'o\l, ~. lll'I:\' I!!'f,Ll:TIS No. PLA·rn X Fw. l. Pralde O:ik, KIiied by lnrncllug Fir Fm. 2. pper Flllls of 1he Des Chutes Rh·er. Forest. Glaciation of the Pu,grt ottnd Region 115 011tc111ponrn ou, OQ11trm11ora11coua Slag~ of JJoMcr Lake. Dulla• of Ma l~r Lake. TNb11lo,;J Laks,. ---1 Early I.Ake Rn 1. L ke Pnt•llup. f 100 tt. Black l.alle outlet) Enrly Lnb Tacoma. and blll1•r11t100 oC Ea.rt:, Lake ftua II. Lllk Nls1111ally. t!!Uncoom nod \ Lake Puyallup. ( .hnmbe.rs l?rnlrle outl t ?) I S~rtnnllcU •w PoltM. Lok 'J'nc mo. Retreat ot Gin I r Front. fte.form111100 ot Lake Rll.Ssell, Contloocd Gh1elnl rtctren Liter Lake Rn II. Lake llokoml9b. (100 tt. PerehnJ n:> k cluuJ. Lake Dood. (m.lBh nel to Bia.ck IAk • outlet. Gladal [.ak a.mma• 11.keti Puye.111111 no Tacoma Lak ooho11.1!1b. coalesced w1th Lnkr nussclL) (J:?O It. Percival ·n•1•k cltnno I Brlnnon o Bh1.clr Llllre 11u!1~t. Lue& lledmond (l lta. Puyallup, Tacoma. kokoiobb. • hl'tlotk e1lll.. ood a.nd ammaml h cont ced Ith Lake Ro .ell. GLACIAL LA! S DURING THE AD NCEJ OF THm VASHON P GET SOUND LACilllR. The low divide l., twe n the ound and the h ali I er ha been hown to be due lar e]y to depo it of th Yashon In. ier. Evid n hn been found ·hicb rgue that th he hu.li - ound divide , a at the arrow near Tn omn during the interglacial epoch, in tend of 1vhere it i now. U U1i onolu ion i <'Qtr ct the tr am flowing in the inter lacinl outh of U1e rurrow were thC'n tributary to th h hali . ati factory ,,idence ugg t that the Rood anal interglacial river flowed t.o the b bali through the .aiatlock ath1 a.y. If lhe interg1acial draina wa di po ed a ug e t d above th advancing Ya h n lo.cier could have ponded water in front of it only in the t · ugh of Admiral y Inlet and it ributary vall y . Enr1y drainage of this ponded water should have occurr cl aero the low country about the northern part of Hood anal to that trou h nd thence to the h hali . Advance of the ic I ould earl • c.Jo thi , however and would hilt the outlet of the upposed lak to the ite of tJ1e o.rrow . lH Bulletin o. , Wa hington Geological 1.1,rvey Ilere it may be con ide1· d to have remained until ad an c of th glacier to that lati u e d tro ed the lalrn. i tle positive data can b ·p cted on such a ubje . 'l'he hyp thetical lake level lo.y below i50 feet a.t. its high• t, and doubtle became lower whil it exi ted, by the dowu- utting of the a.nows. Dclto. dep si hould have been form d in u h a lake but they are not likely to have been pre erved ince t11e were immediat ly o ridden by a grea glacier. delta d po it wbi ·h m1 be connected with thi hypothet i nl lake of Va bon advanc o cur in the city of utt1c, on the harbor lope of • ir t Hill It tructure hn h en ll , p d by treet grad.in , c pecially at the oraer of en a reet and Sixth Avenu . ( l. VII Fig. 1.) Its maximum thi •]we s i about 30 f it 1 d dip outhwe t, u.nd it r t un- onformably on the r tifi d dm.iralty clay i hich b neath th a hon till form the hill of the city. The a hon till co er the delta b d and ha a m · mum thickne · h re of 15 feet. ' he triking feature of the delta ection i the pr en e f frngmen of lignite wbich in ome strata con titut half of th mate.rial of the for t . The small round d many of them b fo fragment worn fragment of a mammoth tooth a al o be n found in the e fore et bed . Th line of contact e w n the fore et beds and th a hon till i about 200 feet abo e l el a. figure whi h u·ould bring the water le el within the limits impo ed y the reti al on ideration . The e foreset gra el trnta nre posed alon the lope fo1· nearly fi e block . Tbey b e not een een to run a k into the hill and thu to beJong to the Admiralty serie . Th ppar ntly constitute a d •po it on the hill 1 pe int rmc The ice oven·ode thi uncon olidated delta material without di tarting it en ibly. In one ection a cobble wa found to hav proje t d f 1· half i d.iurn ter above the ubjacent gravel urface and to have been held o rigidly that a fun-ow at lea t three feet long wa f rme GL CIAL LAKES OF THE TIME OF MAXIMU1\1: VASHON GLACIA 'l'ION. fo impinging on the north rn lopes of the rock hill wlricb lie onth of the drift plain, the Vashon Puget Sound Glacie1· undoubtedly dammed many mall valley , and produced a series of marginal lo.kelets which have left no record ~·cept in a few cases where surviving drift-dammed lake and wamp attest their former exi tence. Larger marginal lake of the maximum stand of the ice a a rul left better record . '.M.lNO:U. LAK.ES OF TltE DALD RILLS. The f ont of the Puget ound Gln.ci r cro ed the i qua.Uy Valley at LeGrande where the river emerge from the foot hills of Mount Rainier to the plain. Though an ideal ituation for a glacial lake if the va.lle above were empty, the probable presence of ice from Mount R ainier is thought to have pre vented the formation. of a lake. On the northern lope of the Bald Hill , there were mall glacial lake , noted in the chapter on the terminal moraine ( Ch. II) . These ai·e recorded by mar hes and drift-dammed lakes which still ex..i t. The1·e ar e several bold outhern lopes among these hills where the volcanic agglomerate ha been weatl1ered so deeply a to leave the larger bowlder of it mass i olated on pedestal , forming anvil- and obeli l<-shaped projec tion . Among the e are cattered erra.tic pebble . Since the e pebble lie higher than the moraine. and on slope facing a,rny f:rom the glacier th y are referred to ice floating in marginal wat-er g1aciaily dammed among the hill . Gla.cibticm of the Puget own.d Region 117 GLACIAL I.AXE OF THE DE CHUTES RIVlm V.U.LEY. The Puget ound Gla ier era ed the De Chutes River valley where it emerged from the Huckleberry Mountain. The upper part of the De hute Valley was protected by the Huckleb rry l\Iounta.in agAin t in a ion of ice from fount Rainier and it wa damm d by Puget ound ice at it de bouchure on the plain. 'l'h.i gave ri e to a glacial lake. The pebbly clay depo ited in thi la.ke probabl i re pan ible for the flat on which j the grnup of mall farm and the Bald Hill chool, a mile or two above the moraine eras ing. The lake depo its and the moraine have be l'I re pan ible for the 'Upcrpo ition of the 11ver on 11 rock spur of it pre- ashon valley, and the consequent formation of the De Chute Fall , a beautiful double cataract with n picture que canyon below it. (Plate , Fig, !) . An intere ting problem is afforded by a comparison between the i qunlly and De Chute rivers where they enter the Puget Sound drift plain, Both were diverted after the gla.cia tio.n, and forced to cut through rock for a hort di tance. Both po ess deep post-glacial canyon , but the Des Chutes has a cataract at the head of its canyon while the grade of , the Ni qually r.i es gradu11Uy through the can •on until it is at the Jevel of the pre-Va hon valley. The rock i a fairly uniform G.LACL\L LA.JU: OUTll 01<' 1\tC tNTOSR. ear Mcinto b and Tenino the glacier at it maximum ex tent rencbed a mile or more beyond the southern margin of the 118 Bulletitn No. 8, Washington Geologicttl Su,·vey terminal moraine. This i recorded in scatter d glacial gravel on the hill south of the Clear Lake valley the moraine lying north of tbe valley. The outhern lope of the moraine here has numerous rock outcrop and it appears that a line of low 1·ock hills, nearly paralleling the edge of the ice wa here o erridden a hort di - tance. The e hills appear to have caught the ba al de ri on thei. northern Hanks and thu to have determined the location of he moraine. The erlra-moraini gravel above noted doe not repl'esent a depo it from ponded water becau e ovcT mo t of the lull lope the topogtaphy is uc that a lake could not have existed wl1erever the ice front tood. Thei·e js further evidence that the ice cros ed the Clear Lake- Tenino Vall y outh of the moraine and rested against the hills on the south ide of this valley. This evidence i found in the delta deposits of the two glacial lake who e existence required an ice dam bard against the hills outh of Clear Lake and Tenino. l3ack among these forested hill there i a beautiful valley fiat lying a ljttle we t of outh from McIntosh, and a. little outb of e1;1, t from Tenino. It ramitie in several green meadow arm among the hills, and drains northward to Scatter Creek. At. the glacial maximum tbi northward-draining valley was dammed, and out.flo,v from the re ultant lake was aero the divide to tl1e Skookum Chuck on the outb. (See Figure 2.) Sediments deposited jn the lake contributed to the filling of the valley though subsequept wamp depo it ha~ done much al o. A delta deposited in the lake i c1·0 sed by a road which enter the valle from Tenino. Its sw·face i 450 feet above the ea and its .structure U'})OSed in a roads-ide gra el pit, i. perfectly and unifonnly fore et, the bed bemg !!O feet thick and dipping to the outh. The 1eve1 top of this delta is a noticeab1e feature of the local topogrnphy. Though the outlet chfl.llJlel ha. not been found the delta probably record the chief level of the lake. The valley today has an outlet northward 100 feet or o Glaciatwn of the Puget Sownd Region 119 lower than the delta, and eroded in a drift filling in the lower part of the vn.Jley. This drift dam held a lake for ome time after the ice ·thdrew, and the outlet mcandexed in cro ing the glacial accumulation of sand and clay. The stream ba sub equently entrenched the e meanders, and, with the a.s ista.nce of encroaching vegetation ha de troyed the fokc. LAKE 13UOODA, A little more than a mile outh of Tenino, near .Blumauer's ~ delta be&, dipping outhward~ are e."" LAXE CKERALlS. The gra l which entered the hehali River valley at en tralia coming from the Tenino-Bucoda and Stony Point routes, con titute the mo t outhel'll occurrcmce of Vfl hon outwa h of Puget ound. They entered the larger 'alley from he north ea t and were wung back to a northwe t cour e at an angle acute to their route to the hehalis. Their volume wa o great a to fill the hehali Valley up to an altitude of 188 feet con- iderably above the pre-Va hon alley bottom. Excavation at eutralia pen trate the e clean fresh gravels for 75 feet with out reaching their ba e. The ity of hehalis i about four mile. up the river from entrnlia, and tand at the ame altitude on the same flood plain. But , herea outwa h gravels are at lea t '75 feet deep beneath Centralia hchalj i built on a alley fillLng of river alluvium and lacn h'ine depo it , tlild no trace of glacial gri:nrel ha been found u.1 the region, save wl1ere tran ported by human agency. The region of the city of hehali received no gravel becau e the flowing water turned down t ream on entering the hehali Valley at entralia and the invading gravel were carried back toward tbe glacier. Only tnnding water ould have exi ted at the ite of beluui when the gravel were de- po ited for the valley wa dammed by outwa h about entra.l.ia and water mu t have backed up he ewa.ukum, hehali and ' Big wamp • valley . Dammed by Vashon outwa b La.ke behali (Plate XXIII) came in o eJ i ·tence at the time of maximum glaciation. It slowly dwindled a river and wamp d po it filled the de-pre - sion, never being lowered more than a few feet b inci ion of the gravel ·filling. Da~ed by a permanent burier it prob ably wa longer lived than any other glacial lake of th region. It position i the mo t outberly of all water bodies originating in con equence of Vashon glaciation. Frn. I. Section in lhe Stell:H·oom Delta. F'm. 2. Section in tile Ril'll111011d Delta. c·ouu,c, lH'tw,•,·n tur.. ~,ii nut\ fo1•··wl h, 1,1" Ii; lti:"'i r.. ,~, nh~\t1• ~,·u lt•v1 1I. Glaciation of tl1e Puget SaW11d Region UH Evidence !01· the exi tence of Lnke hehali are largely in the to ographic configuration of the region and in the pre- eoce of the gravel fi!Li..11g at the north. A the gravel front a.dwmced outhward on the out ide of the curve in the glacial drainage com· e at Centralia. a delta structur must have been formed ill the lake· but ground n.ter i o clo e to the uriace of the flood plain at Cen ralia, that excavation are filled to within ten or fifteen feet of the u rface and tl e g'{avel structure i concealed. The few feet o-f gravel een above the water po e tream b dding with outh vard dip. Wells a.bout hebali have frequent] brought buried timber to ligh , oak tree trunk having been found 50 feet down in lay and and. o gravel i reported in the well record . LA.KE OF "I!HE CILE.RALIS LEY TR.An. When the flood of glacial gra el wa poured down the length of hehalis alley jt dammed the mouths of the tributar val ley which bore no contributing gmvel train . In tl1e e b- tructed valley lake £ll·o e in the same manner that Lak he- halis wa produced. None of the va1J ,y o dammed ere of con iderable size and 110 lake of con equence we1:e produced. everal linear swrunp nmon the driftle bill about Centralia ue referred to damming of preglacial b'eam valle by the valley train. terrace depo it compo ed entirely of local materja} exi. in the lower cout• e of Porter reek whi b flow from the Black I-I.ills. It reache .a mile back £r m the hehali Valley, and it level probably represent the altitude reached by the gravel filling in the main va.lley. Thi depo it affords the soil and the plane urface w11ich have permitted everal farms to be developed in the low r valley. WA.ODELL CR.EEK LAKE. Waddell Creek which enter Black River from the Illa k Hills, wa · dammed by the glacier at the point wher it merged from the hills. -tanding water accumulnted here to a height of 650 feet, at which altitude a pa we tward through the hill to tLe head of Cedar reek permitted e cape of the ri fog water. 122 Bulletim No. 8, W ashi.ngton Geologicai Survey (Se Figure ~.) Floating ice carried glacial drift back m the valley and di tributed the pebbles throughout the finer clay which sett1ed in the lake. Much of the clay i fine res-idual soil whic1 wa derived f-rom the surrounding hill slopes. The scattered pebble axe found no higher than 650 feet on the valley ides. A lacustrine -Aat Te ulted from this lake similn.r to that of the D e Chute and in a imilar way jt is re ponsible for seYeral farm back in a hilly region which is mo t unpromi - iug agriculturally. GLACIAL LAKES DURING THE RETREAT OF Tl:IE VASHON PUGET SOUND GLACIER. Tl1 wane of Vashon glaciation afforded .ideal condition for the development of a complicated series of glacial lakes in the Puget Sound basin. In many ways thi region r embles the Finger Lakes country of central ew York. In both, the trend of the topographic featm·e i north and south and in both the major form wel'e produced before the 1a t glacia'tion. Ponding :in. tbe linear valley occurred in both reo-ion du.ring glacial retreat and the general rule in both wa th.at with drawal of lite jce opened succes ive lower outlet to the north. But in Puget Sound all water e caping from glacial lake i.n the diffe.rent valley wa forced to pa s over the Chehalis Sound divide into one drainage line. The result of this control of glacial drainage by one pa wo. to lfrrut ubsidence of pond d waters whose valley had ucce sively lower outlets ex po d by ice retreat. Grndually water in the. trough and fiord of ufficient depth in the outhern part ol the area W1ited at a common level; that determined by the pTe ent hchali - Sound divide east of the Black Hills. The water body whose level wa thus controlled ha been named Lake Ru elJ*. Its inception wa coeval with glacial retreat from Budd Inlet the mo t southern arm of Puget ound. It maximum wa at tttined just before it final di appearance the lake then extend- • J. H. Bretz, ''Glacial Lakes oe Puget Sound,'' Jo111•. Geo!., Vol. 18, No. 5. Glaciation of the Puget oumd Regiori, l!i3 iug fro Olympia. nearly to • ver tt a di tanc of nt 1 11st fifty mile . EAllLY LAKE ll 8S:ELL, .LA K LAKE UTLE1'. lucial 1·et.r at aero Thur ton ounty de clop d a low drainug lioe clo e to the ea tern f t of the Blnck Hill the u. e of , hich h discharge from Lake u U wa ontinued after th d e of llie ice had withdr wn £Tom th region. Th.ere wer t , and perbap mor , cl1annel lea in out of this la.lee but nnvcrging ,rithin a. r I mile into one whi h continue a a wide, , ampy valley of I w grn to the Lehn Ii . It i uow o ·cupi d by Black Lake nud luck H.i r. Two of these on er, in hann l leave the 1•11.Jley of Budd Inlet. and one may ome from the head of Jd Inl valley. ( ee Plate XXll.) l'he t o hannels from Bud • Warren Upham (American Geol., Vol. 34, No. '1) haa noted thfll ch.a.unel, which ls pla.lnly recognized l'rom the tTaln, and has suggested th.at It micy have carried 0\'8l'flow from a glacial lake In. Puget S0u11d. Ht6 Bull.etin o. 8 W a hington, Geological Survey n m both of the e u ·t cl channel j that 11. ontinuou tracing aero ha not been mad be au of the almo t impa able nntur of the wamp existing there. Withdrnwal of th f th ice from Thur ton ount 1 ft both the i qually rivers fr e t,0 flow di d of wate:r in t11e unublite1·- al d interglacial valle. . j qually carried a large volume f r when it 6r ·t nt red ake Ru sell in e the bop hn.nn 1 till contribut d the drainage of the north rn nnd e tern lope of Mouut. Raini r. It appear to hav ente.r d he we ·tero ide of the interglacial Gate Path ay Riv r valley aod to have contributed c n iderab]y toward th bliteration of that valley by dcpo :ition of the Sherlock Delta. Tm:: H.Ell..LOCK .LT . Th front of hi anci n river cl n. ri e a ruptly 90 feet abo,1 e the .flood plain outh of her lo k. The altitude of it upper margin i 115 feet bo e tide. nr her I e t the front i I abrupt and the ltitnd of the m,u·gin i 120 feet. n h th lop , fine foreset. b d f roanded ravel ar el.']) ed, dippin northwa.rd t.owa.r the ound. The r r t covering of th L l' .ALLUF. The comparativ tudy of ou wn h ~rmce and hanne] h giv n ati factory eviden e that L ake :Puyallup in the I u a.lJup Riv r trough di Tm: Or,ror HANNEL. The Ohop channel (Pl XXII and JI and Fi-g. 8) which wns the outlet of LRke Pu allup and the route of the arbon and Puyallup 1-iver to the isqually, contain Ohop Creek and Obop Lake outh of the pre ent col and Lake Kapowsin a.nd the Puyallup River north of that point. The col i 595 feet above sea level and Obop reek entering the. channel here f-rom the foothills of MolJllt Rainier, divides on the col, the major portion of the stream turning southward toward the N-isqually and the smaller branch entering Lake Kapowsin and the Puyallup River. AJluvjation by this stream has doubtles formed the divide at this point and produced Lake Kapowsin in the Same way tl1at Bergh Creek ha probably pl'Oduced Ohop Lake in the old cbtin-nel. The earlier po ition of the divide was probubly between the north end of Lake Kupow in and entrance of tl1e Puya11up River into the old channel and the earlier divide was omewhat lower than the pre ent one. / At the present col the val] y is about 500 feet wide at the C.. bottom and 340 feet deep. At the cros ing of the Mount Ra.injer road, a few mile from Eatonville, it i 200 feat deep and perhaps !WOO feet wide. B etween these two points there is a descent of about 14 feet to the mile from tbe pre enh divide in the channel. From thls point to the lowe t terrace of g)e. cial drainage at l\fcKenna, the grade i about 10 feet to the mile. The narrows of the Puyallup River vnlley between Ko.pow in and Orting are caused by the superpo ition of Lhe earlier outh- 1vard-flowino- drainage on a rock hill buried in the drift and the maintenance of thls course by lhe present northward-ilowing dra.inage. The we tern side of the PuyaUup trough lie at an altitude of about 550 feet from a point near1 two miles outh of Orting to a point three miles north of that town. We t of this rim i.s lower land lea.ding to Lake Russell. Whether this altitude uf- 1~8 Bulletin No. 8 Washington, Geological Siurvey liced to hold Lake Puyallup to the. Ohop channel bas not been yet definitely determined. If the Kapowsin col ha been rai ed 50 feet or more. by aJluvie.tion of Ohop Creek it i probable that the lake dischaTge held to the Obop channel and with the Car bon, White, and Puyallup rivers swelled the volume of the isqually until the glacier withdrew nearl to tl1e bifurcation of the b·ough ""a.Dey near the tmrn of Puyallup. THE CLoVJm CncEE;K CHANNEL. When this region was cleared of ice, Lake Puyallup found a new outlet we tward through Clover Creek channel to the Steilacoom Plain south of Tacoma and thence to Early Lake Ru seU in the vicinity of Steilacoom. ( ee Figure 8.) The col in the Clover Creek channel on the summit of the bluff outh of Puyallup, is a little below 4,00 feet in altitude. From it a wcll marked glacjal river course leads south, and then northwe t, to the broad gravel plains about Spauaway Lnl..e. Salsioh Junction, on the Tacoma Ea tern Railway, i on the brink of the old valley which the railroad cro ses at thi place. Lake Puyallup persisted with gradual northward increa e of area until t.1,e site of the city of Tacoma was cleared of ice. A lower pa s was then opened, and be au e of thi nnd other change , the history of Lake Puyallup may be considered to end at thi time, :its area be coming part of Lake Tacoma. LARE TACOMA. A very intere ting region in the tudy of the glacial lakes of Puget Sound lie jn the southea tern part of Tacoma. The bluff on which thi city i built is a large reentrant angle open ing northwa.i-d toward the tide Bats of Puyallup River. The busine ection of the cit lies ou the we tern jde of the angle. re idence ectio11 occupie the southern ide wl1ere the glacial lake history is to be read. ( ee Fig. 9.) THE T.ACOM'.A DcELT.A. A number of grnvel pit are located in trus part of Tacoma, forming amphitheater-like niche in the face of the blulf. The all aaree in exhibiting delta-bedded gravel which dip between north and northwe t toward the Fm. o. portion of Lb ~ty o! Taco11111, sl1owlnir lot'lltfon cf the. Tacoma Dcltn, th• ~arloue ilf lo It. Llt~ Ilubll or th• utb 1tuoo11m han.uiol. nod Position ot I~ Fr nt st Time oC Deli.a 1"orm11tlon. 1SO Bulletin No. 8, Washingto1i Geo.logical Survey present Sound. The altitude of contact between top et and foreset bed however, i not the same in each pit. In the_pit e_wt of tl1e Hawthorn School, at Thirtieth Street South and D Street top et beds 10 feet thick re t on foreset bed at an altitude of !265 feet. The delta ul'face above the pit can be traced easily southward with a ri e of 10 feet in half a dozen blocks. The delta flat here is a noticeable feature of the topography. To the northeast McKinley Hill, SSO feet above tide, ri es like a buttre between th.i delta fiat and the adjacent Puyallup trough. Another pit has been opened on tl1e ea t side of Galla her's Gulch, a few blocks nearer tb ape.x of the right angle described. bytheb1uffs. The lower portion of the pit is in .interglacial gravel and expose an intercaL:i.ted stratum of Admiralty till. A thin layer of Va hon till caps the old tained gravel, and is succeeded by fresh unstained unconsolidated gravel with an abundance of granite pebble of variou kind , and none of the oft, pink, purple, or gray lava pebbles found commonly in the lower gra el. This fre h matet·ial can be traced without break to a pit in the delta-bedded gravel near by, and definitely places the delta bed as sub equent to depo ition of the Va hon till. The Harrison pit is focated-at TocWD, :v~e and Thirty- second Street South in the apex of the right angle. Its foreset strata dip to the northwest, and the altitude of their contact with top et bed is SiO feet above tide. The gravel here is ~"PO ed to u. depth of 60-70 feet, all but the upp r few feet being fol'eset bed . If the de}ta flat outh: of the Hawthorn School be followed sout]leastward the direction from which the tream came, as indicated by th.e foreset bed and t11e grade of the surface, it lead to an abrupt descent to the Puyallup Valley, L treet lying along the brink. This lope is omewh t irregular and has no pit like the northwatd slope jus de cribed. Wel1 penetrate a clayey gravel unlike the material in the Hawthorn and Harrison pit . Till i expo ed in ballo\V cuts and at the Glaciaticn of the Puget oumd Region 181 ummit of the lope, gravel bedding record' curr nt flowing northward a, ay from the lope and ont the 6,Lt. On the adjoining higher land about these delta gra"cl there ar no evidence whatever of a tream tour e which could ha e upplied them. All evidence collected point to the L Street margin of tl1e Hawthorn •h ol delta fl t a the ow·ce of the gravel. The bluff here d~ cending to the Puyallup Valley be111·s many of the mark of an ice contact slope. The c-;;;clusion is evident that the river which de-po ited the Tac ma Delta came directly from the w·fa.c of the Pu.,.et ound Glaci r whea its front lay against the ea t ·lope of tbe del a .flu.t de criLed. The lack of harmony among the altitudes of the tops of the fore t beds records 11. water body with changing levels. Thi is to be expected , hel·e a glacial margin is adjacent becau e change in it po ition may change t.he location and level of the outlet. uch was not, however the cau e o·f the vai-ious altitudes of La.ke Tacoma' surface, as will be hown. THE SoUTB: TACOMA Hil."'?\'EL. Q_allagher' _Qul.cl1 aud DeLynn tTeet ulch are two po tglacial ravine which enter the Puyallup trough at the ape...x of tbe reentrant right angle in the bluffs. Both are utilized b railroads to a cend the bluffs. The orthern Pacific follow the DeLynn treet Gulch to an a.ll:.itude of !230 !eet, where the t·a,-rine l1ead in a flat-floored valle:v one-fourth of a mile wide, \nth no pre ent tream. Terrace of thi alle floor into which th D ynn treet Gulch has cut, extcnd toward the ound on bbth ides, while westward along the orthern Pacific track tlJe grade which follow the old valley at once begins a gentl de c nt toll""al'd the Steilacoom Plain . The old vaJley at the he11d of the gulcb i 70 feet d ep. It hl!l'e po ses es o. terrace fl.50 feet above tide. Farther outh, a high level gra el terrace on the we t i.cle of the abandoned valley a.t about 310 f t Above tide ramifies back am.onCJ' the till ridge , hich bound the valley. I location i approximate) ve t of outh 'l'acoma, which i built on the channel 1loor. Glaciation. of the Puget 0U11d Region 133 on11ELAT10 ' OF TA 0111A lilLTA A....·•,rn llA •.xeL. Here then the e apewi. of a con iderable qu ntity of water who e our e wa outhwa.rd. The channel head on the 1·im of the Pu allup trough near tlie ape., de crib d. Water di charging through it deepened it at 1 a t O f et. Behind it wa t11e water d in which lbe Ta ma Del a wa built at level between !65 and 3~ f t. The1·e can be no he its.lion in cor relating outlet an.cl delta level even though altitude are not the rune. It .is ufficient that the rang-e in altitude of the out let inchtde tbe delta level. Tb re i no other place for di - char e o! L ke Tacoma. f the !l.rt'ow had been open, the delta level would have correlated with the Black Lake channel and th Tacoma. Delta would belong o Lake Ru ]] who e high altitude wa more than 100 feet lower than the lo e t 1 vel of th Ta oma lta. The d' repR11 . in levcl of del n. and outlet i imply becau e the cbnnnel continued o carry glaciA.J drainag and wa eroded after ice had withdrawn from the head of the Tacoma Delta. { ee ig. 10.) The mo t we tern level f the TFte ma Delti\ i the bighe t, and tl1 mo t ea. tern i the low t. L, thi i recorded the po ition of the ice front on the ite of Ta.coma while the outl t chaon -1 wa lowered 515 feet. Slight reces. ion during thi time allowed Jower delta urfoc , to form ucce ·iYel 11 hn1rd, their po ition bein..,. determiued by th unknown our e of the gla ia.! tream nnd the local outline of the ice margin, and thei1· altitude by the dowucutting of the 011th Tacoma channel. Bo..iJey Willi bas di cu ed the Tacoma Delta in t, o paper . • H conc.1uded tba the above d crib d outh Tacoma. out1et d1a.nnel , a, ~he cow- e of he river which depo ited h delta ra 1 . In rerrard to thi conclu ion. it i to b noted (l) thu.t lhe clfrec ion of dip of the for eds i in all case toward not away from the outh Tucoma channel, and that the ncarc t bed (Harrison pit) dip n.lmo t directly toward the 11 arb. channel head; • Ta.coma Folio.• 'o. 54, . S. Geol. Survey 11199. Bull. Geo!. oc. Amer.. ol. 9, 11197. 154 Bulletin l\ o. 8, Washington Geological m-vey (2) that the grade of the Hawthorn cbool delta fl.at does not pe1·mit the: application of hj interpretation; and (S) th,at the grade of the South T acoma channel itself a.b o lutely fo1·bid hi int rpretation 1,mle tilting has re er ed tbi,c; channel grade in a region where postglacia.l t' ting has not been recognized. Du.ta on the teilacoom Plains to be pre- ented shortly will throw further ligbt on the ubj ect. TRE Ul3U1l DELTA, A mile a t of the town of uburn the orthcrn Pacific Railroad ompan ha excavat d exten sively in the face of the valley bluff for ballo. t gravel In the ection thu expo d there are plendid fore et delta beds, ome of U1em 50 feet long, dipping we t toward the pre-Va hon trough in which Auburn lie . The delta nature of the blu.ff · ,vould hardly be recognized from the topography. The gn1vel has two ummit level at 235 and 260 feet above tide, but almo t immediately back from the edge of he delta its urface descends in a huge kettle that de troys completely all semblance to a delta urface. Wl1ite. Lake lie in thi kettle at an altitude of 105 feet. The outh side of the kettle completely brea.ches the delta front and pre ent a re embl1.1.nce to a rivel' channel, as Willis has interpreted it. The nOJ:tbern rim ri e to 160 feet however and the pre e.nce of many smaller irregular kettles on the delta urface i ati factory evidence that the Auburn D lta. wa built on the mt1.rgin of the ,vaning glacier block of who e ice were buried in the river depo it to melt out a.!tcr depo ition bad ceased. The obum Delta wa deposited by Green River in glacially _ponded water olong the margin of an ice tongue lingering in the ite lliver trough. The corre pondence of level in the uburn and r.racoma deltas strongly uggests that Lake Ta omn. po e ed a long marginal arm of water reacli.ing northward to uburn on the ea t side of the White River trough immediate!• after the T aconrn. Delta was abandoned and after the ice had withdntwn from contact against the bluff at L treet Tacoma. The lowest level of the Aubw·n DeJta corre pond· w-ith the col in the South Tacoma cbannel and Glacia.tio'fl of thq Puget ourtd Region 135 completes the l'ecord of rrver depo. ition to accompan all stages of erosion of the outh Tacoma chaune1. o other outlet exist for the waters in which the ubuxn Delta was built except the arrow , and if the had b en open, the Auburn Delta would correlate with the level of Lake Ru sell at least 65 feet lower. THE K:EN1''YDALE D:<A, On the ea tern blufl' of Lake Wa hington about Kennydale, lie a broken- urfaced deposit of a.nd and gravel of con idernble extent and depth. Else where the lake bluffs are of till. A level Ul'foce exists at the sWILJD.it of the lope about a mile back ftom the lake, ~90 feet above the sea. ]\fay Creek l1as cut a canyon into tbi perhaps !25 feet de p. Fine sand constitutes the urface material, and well tratified gravel i found in hallow excavation . Followed back from the lake, terrace fragment are re placed y a continuou floor on both ide of the creek. It has a mootl1 urface, ri e gently ea tward, and i composed of w ll wa bed gravel. Definitely ut blu.Jf border the outhern side of tbi valle ,, and the canyon of l\Iay Creek shaUows l'Rpidly until the trea.m tluee mil from Lake ashington, i flo,ving in a wamp , wjdc-bottomed old channel ju places a qaar er of a mil wide 'th bluff 50 feet high. This old alley i ve:r di tinct alon the foot of quak l\Iounta.in (Pl. V, Fig. 1), where a col in it about 315 feet auove sea level divid the head water of l\Ia reek and I aquah Creek. Will.is• note the e..'ti tence of the upper portion of this old valley and a cribe it to the work of Cedar Ri er sometime during lacial retreat. 1'he strength of development shown by the channel j ~ qua] to that ~·hibited in the pre en lower Cedar River valley. and sugge t a con iderable period when the 1· ivcr empti d into the pre-V asbon vaUey four mile north of it p1·e ent junction, and adjusted it channel to a wate.t level about 290 feet above tide. The Kenn dale Delta i too high to he correlated with Lake • Tacoma FoUo, No. 64, U. S. Geol. Survey, 1899, Balley WiJUs and 0. 0, Smith. 136 Bul.letitn 1' o. 8 Wa.shinglcm Geological urvcy Tacoma levels north of the Tacoma Delta. Thi· latter form d flnitely prove tha Lake Tacoma ,va lower d to an a1ti tu le of 265 feet at the ime the ice. ontact lop of L tre t wa abl.llldoned and the lo.ke became free to e-xtend northward. Th Kenoydale Delta j to be interpreted more suti fa.ctorily n. a dep . it in a local lake between tJ1e ic tongue of the Lake Washington Ytdley and the bluff b incr tributary either to Lake Tacoma or to Lake Rus ell which ubsequentlv r placed the ea.l'lier ,vat T level . CORRE.LATIO ' OF LAXE PUYALLUP T OM.A Nl> Jl.USS.ELL. TltE TEILA OOM PLAtN . Thi hi.rge aTea of outw h gravel po e e a uniform we tward de cent from the broad- ning out of lover reek channel near anawa Lake to the abrupt truncation of the plain by th bluff of Puget ound on the we t. ( ee Fig . 8 and 10.) The grade commonly is b l:,ween O and 15 f et to the mile. The lll'face of the plains i di ·po ed in delta-like tenace in many place , and long channel are to be re ·og1lized on th we t 1·n portion, de cend ing westw111•d with the g neral lope. ome portion ar rolling and sugge t morainic topotrraphy, but till j rarely n1>0· cd in ection . Faint ivlimti ype mounds ar found on some of the plains, outhea t of Hi1Ihur t f r x:~mpl . The area i Jargely natural prairie interrup d by for t d portion . Th coo.r gra elly oil prO\•ide at1 exces rv lUlder drainage and the plains are of little value agriculturall . The r gi.on ba gi en tb . S. Bure a of oil thei · Spanaway type of gravelly soil. ak Puyallup empti d through th lover reek hann 1 ont the teilacoom Plains at their astern terminu , hi1 · the northern ide of their area 1·eceived the dischat·g fr m the earlie t t1J.ge of Lake TRcoma then u mall body of water ju th re-entrant angl \ hich contain the Tacoma D lta. Fol lowing retreat oi the i e from the L treet Jo e Ln.ke Puy nllup water fow1d a lower outlet tbrou h th outh Tacoma channel n.nd became a part of Lak Tacoma. By the u. e of b th of the e di chargeway the g lacial gravel pr viou ly Glaciation of the Pu,gct omid Region 137 depo ited on tl1e teilac om Plain were reho..ndl d and added to. Thoagh the gradient i low for trerun-d po it d gra:vel it · pura.lleled in man plnoe in uget ouud outwa h, where oth r condition make it certain that .·uch "rad ,vel'e pro duced only b glM.ial drninage and that the are without di cen1..ible . ub cquent deformation. The we twurd-facing bluff' which terminates the tci.lacoom Plains flfford furth 1· indi putiible c,•id nee that tl1ey al'e tream gravel·. The t wn of t ilac om i built on the we tern lope of a l1iJl of morairuc a pect which d C aboYe gru,-veJ plain on the north ea t and outh. and int rrupt the continuity of th ir bluff lin on Puget ound. ( C'e Pl. XII and Fig. 10.) lmrnediatel north of te.ilac m the bluff i of fr h gravel for two mi.le wjth an e\'Cn ere t line of 180-lOO feet. orth of thi to Tacoma he bluft' e.~o e till irfaces und edge of truncated dmiralty sediments Yi ing to 400 feet above tide. The hill on which teilacoom i buiJ form the blutf for lh1·ee miles outh of the town and i ther1 u c ed d by a bluff of fl-e h gravel , ith e en er t line-, nowhere more than ~O feet high, thi con inuing to the mo11th of the i qua1ly lli er. The. gr-aveJ bluff t·on titut the we tern edge of the teila coom Plains. TllE TEILACOOM DEt.TA. E:artcn ive e;, cavatjon have been made in the fuce of the blu:ff north of Steilacoom by the Pio neer and and Gravel 'ompa.ny of e.attle. The gravel i sluiced out b hydraulic methods carried to the bunker and there orted all by g1·a ity. The pit are abandoned when th ir floor are )01 ered o that running -.. ate1· will not succe fully carry the gravel from pit bend to bunker. Great amphi theater ar thus formed in the bluff, and the tructure of the gravel is spl ndidly hown. ( ce Pl. XI Fig. 1.) Without exception, the material from bluff top to ea level is fre h, un tained uncon ·olidated V ti.Shon gra el and thi gravel i di po ed e erywhere in fore·et and top et bed . It eems evident that the hole wall of Puget ound here has been advanced on the inlet by delta grmvtb. 1S8 Bulletin, No. 8, Washington Geological S·11,rvey The large t pit has ides 100 feet high in which, at the time of e.:xamina·tion, great, unbroken foreset beds certafaly more than 100 feet long, were expo ed without inte:nuption. The e beds de cend we tward toward the Sound witb an avel' age slope of 15° . o faulting or other deformations have affected them. Above the long unbroken fore et bed i a stratum of top et beds, about U feet thick near the eaward end. Shallower fore et beds overlie tbj in turn, witb a depth of 10 feet, and their truncated edges disappear upward in the surface oil. A broad ridge of gravel, overlying the upper fore et. beds, i cut. in section by the outh ide of the pit. With such evidence, no hesitation can be felt in aying that the teilacoom Delta was deposited in rising water. 'l'he water level stood for a long time at the upper plane of the great Ioreset trata which largely compo e the ection. The alti tude of thi is be.tw en 160 wd 165 feet. The delta front wa a-tended at thi time until it reached much beyond the present bluffsJ top et beds being U feet thick here. Originally they must have reached out with gradually diminishing thickne s to nothing at the delta edge. A ri e of the wate1· level to 180 feet n ued. Fore et beds were now begun back on the submerged delta plain and were advanced ell.ward until the second fore et stratum 10 feet thick at the edge of the bluff, wa depo ited. II top et beds e,,er accumulated on the e, they l1ave been removed by ubsequent changes. The cro section of the broad ridge o •e.rlying the upper fore et bed ha a diagonal trati6cation which dips landward at about the ame angle at which the fo1·eset bed dip ea.ward. The ridge lie parallel to the dge of the bluff. ro explanation for this form ha been found save that of a wave-built ar. The trata are not arranged with seaward dip to record accretion on the expo ed face, and the only o.ti factory n'-plan11.tion i that the bar wa being driven inland aero the top of the delta. G1-aciaticm of the P1Lget ou:nd Region 139 by wave which roded the eaward face, and threw the gravel over its crest to be depo it d in the anomalou 1 dipping bed .• 'I h urface of the d ]ta w11.s 01·jgi11all_y thinly fore ted but to upply the gra..-el work with fuel tbe fore t bas been suffi ciently remov d to expo e everal acre of urface. It is sur pri i.ttg hat the configuration of the urface i irregalar and un ystcma ic giving almost. no hint of the natu11e of lhe under lying material. By the aid of the nearb ection , the irregularities are iden ti:6.e~ with ome re erve, a bar and channel on the top of the delta. The occurrence of a terrace !00 feet above tide back a. little from tJ1e bead of this pit, and not cut so as to show tructure, pos ibly indicntes that the water level ro e 20 feet above the upper foreset beds of the section . Tlle pre ence of the sup posed bars above the snme foreset beds is further evidence of such obmergence. Thi highest water level ma be con id ered a of so hort a duration that the delta plain was not completely built up to the new level. The gravel pJain back from the edge of the teilacoom Delta rise very gradually eastward a.nd widens oat as the Steila coom Plajns. A somewhat lower podi n o( it gradually narrows northward until it become the old outlet channeJ of Lake Ta coma. The water of this lake lowered the grade of the outb Tacoma channel from about 13 feet to the mile to a little more than five feet to the mile. TaE EQ ALICREW DELTA. The gnvel bluff between teil acoorn and tbe month of the Ii qually R iver i being a."J)loit d for gravel by tl1e ame company which is operating in the Steila coom Delta. Two pit have been opened half a mile north of Sequa.1ichew reek and in one of them the strueture of lhe gravel is clearly revealed. n the out.h ide of the pit, during the ummer of 1911, the tructure hown wa, identical ,vith that de cribed for the teilacoom Delta. The highe t level • Gilbert. !.D Monograph 1, U. S. Geol. Survey, has described a slml lar procedure or wave actlon ln Toronto Harbor. 140 Bulletin o. 8, n ashingto-T/J Geologicai Survey of foreset bedding i here at an altitude of 185 feet in tead of 1 O feet and no bar ex.ist ab ve it. The am hi to1·y i thu recorded tl1a ha been read for the teilacoorn Delta. The urface of the qualicbcw Delta i omewhat irregular nud fail to 1·e. olye itself into channel or bar . A ati.sfactory explana.tion fo1· the irregularitie ha not been found. For et bed exi t in the ea di.ff of the equalichew Delta and back in the valley of equalichew '.reek. Thi- parallels th occun-ence of fore et bedding in the valley of 'hambers Creek which similai-ly incises the teilacoom Delta. Doth creek vaUey ho, the delta gravel on the coa t to be the full deptb of the blu.ff he-ight, though they become ballowe.r a mile inland. At the head of the equaliclmv reek, near DuPont the gravel i but 50 feet thick. It i here cro bedded in intricate fa hion indicating changing currents during a ri ing water level. rom the head of the ravine, the level prairie surface extend ea t ward with lowly rising altitude, being one and the same plain which form the teilacoom Delta front. Thu the teilacoom Plain are proved to be a g1·eo.t flat o! tream aggradation, who e materials we1·e rehandled and brought to lower gradients by uh quent , ork of les heavily laden waters corning from glacial Lake Puyallup and Tacoma. The ab1'upt we tern face is clearly a delta front -in the glaciaIJy pond d wnter of Puget Sound. El ewber the plain are ur rounded b ground and rece sional moraine uria e of higher altitude . lVilli and mith• have interpreted the teilacoom gravel plains a. the deposit of a glacial lake who e di charge wa north ward by the lover reek and outh Tacoma channels to the Puyallup trough. Thi conclu ion i untenable for the follow ing rea on : (1) The two channels descend toward not away from, the p1ain . • Bailey WUlls and G. 0. Smith, Tacoma Folio, No. 64, U. $. Geol. Survey. Glaciation of the Puget ownd Regio1~ 141 (2) 'l'he plain continue the lope of tbe channel we ward to the bluirs of the Sound. (S) The dcl.ta bedding of the teilacoom and equalichew deltas in LAKE J,,'lSQUALL:Y A rn THE OBLlTER.ATIO • OF :EAl\LY LAKE RUSSELL. The lowe-, foreset bed in both the teilacoom an.d equali cbew deltas, at a.n altitude of 160 feet, are "'ithout que.tion, to be -referred to Lake Ru ell a it highest level. The ri e in level to 180 feet and po ib]y fl O feet can only mean a clo ure of Black Lake outlet while the two deltas were still growing, the lake finding a new outlet at higher level cone pondil:lg to the le el of the higher fores et bed ·. Dif'ferentia.l cru tal movement do not enter n a po sible cau e of thi change in outlet the evidence throughout the Puget . ound country being that there has been no warping nor tilting ince the Va hon ice wa nl jt maximum. Jo ure of the outlet by land lidc would be impo ible. There wn no vul anism in the region dming the Quaternar. . All but one of the po sible way of causing thi rise in water level a.re ruled out. Thi one i the clo. ure of outlet b. readvance of the glacier. Thi conclu ion ha been reached by a proc of elimination becau no corroborati e field e idence for uch ad vance has been found. A readvance of the glacier -ufficient to clo e the Blac.k Lake outlet to drainage from the ca tern part of the region neces i to.ted a frontal po ition ill the ,·icinit of Lacy and the morainic country enclo ing the lake of Thur ton County. ( ee Fig. 10.) Advance to thi po ition would tw·n he i quaJJ River 142 Bulletvn, No. 8, 1Vl4'37tingt01i Geological Surosy and the drainag of the teilacoom Plains aero s Cham er and Bu h prairie , as before the birth of Lake Ru sell. It would o . horten the area of ponded water in Budd Inlet that, at the mo t only a small lake would have remait1ed about Tumwater. During thi advance the areas of Lake Puyallup and Lake Tacoma were not seriou ly encroached on. Doth the Clover Creek and outb Tacoma channel continued to be u ed and drainage acros the gt.·a,•el plain adju ted grades to the 180- foot level. At this time the front of the ice bad an approxi mately northeast- outhwe t cour e between Tacoma and Olym pia. ( ee Fig. 10.) For thi body of water, changed in level and in outlet, the name Lake Ni,qually is proposed. The term Early Laks Ru, sell is -re tricted to the glacial lake occupying the southern por' tion of Puget Sound before the advance which formed Lake i qua.Uy. When the ice retreated again, the lake which re occupied the outhern po.rt of the Sound did not differ mate rially from the fir t in depth or area. It again di charged aero the Black Lake channel at the 01•iginal 160-foot level. It appear, however, that clearing of the arro occuned during this retreat, and that Lake Tacoma was tho lo,vered, and became a part of Lake Ru ell. The evidence for this conclu ion i the fact that the 180-foot le el of the Steilacoom and equalichew delta wa not eroded ubsequent to the re establi hment of the 160-foot level di charge through the South Tacoma channel having appar ntly cea ed. If this conclu ion i correct, the Auburn Delta of Lake To. coma wa building at the time Eady Lake Ru ell wa oblit erated ; the Tacoma Delta had been already constructed and abandoned th ice front having withdrawn from the L S reet lope. At be t there are weaknesses in the preceding orre lation which can be removed only by further study of the region. G-LAClAL LAKE ON TRE l LATER LAKE RUSSELL AND THE SHELTON DELTA, With the clearing of Hammersley Inlet the water oi Lake Rus ell backed up into it and into the two tributary valleys of Shelton Creek and Oakland Bay. A tbe edge of the glacier withdrew from the vicinity of helton, outwash gravels car ried southward across the tract between Hoods Canal and Hammersley Inlet were deposited in a lt,nge delta on the north side of the Shelton Creek a,1·m of Lake Rus ell. (Fig. 11.) The hont of this delta now forms at lea t a mile of the northern bluff of the valley. Seen from Shelton, a few feet above tide, the crest of the delta front is strikingly level According to the aneroid, it ranges between 160 and 175 feet in altitude for the unforested mile of length which ha been e.-umined. Fore ct beds were seen in two places on the teep front. The ma..teria.l is gravel with sand in oroe portion . Back from the edge of the delta, the sW'fa.ce is the typical out, ash prairie of Puget Sound, with a thin fores·t covering much of it a few mile farther north. The w]1ole outwa h plain lope gently oulhward toward the delta. Glaciation of tlic Puget oun.d Rcgi()» H5 There i no grnvel on the outh ide of Shelton 1·cek val- 11? . Tb l p nr o..11 o! round m ra.ine. and ri hi h r than the delta on th north ide. • rom tlu · fa t and fr in the uni form level of the e(lge of the d 1 ,, it i, inferred that the helton lta I a. n v r huilt complet 1. a ro the creek valley thouab a ,•ance of th fr nt of tbe LAKE KO OMI H. The depr n of Hood- anal i · cli,; L!.\.KE HOOD. The second tage thus inaugurated may be named Lake Hood. While the Clifton outlet wa u ed, the water of Lake Hood gradually extended northward for neal'ly the entii·e length of the Canal. As in the ca e of L ake Puyallup, the only record of thi.s lake is its outl t . Figure Hl indicate the area of Lake Hood at it ma.ximuru. TRX CLIFTON CHANNEL. The Clifton outlet channel is a definite Jeature a i·o the divide on which it lies. It is 60 feet deep at Lake Deborah in the col, 220 feet above tide. This Jake now drains both to Cases Inlet and Hoods Canal. Gravel terraces exist along the channel, and one terrace on the east side continues as a small che,nnel directly eastward to Cases Inlet, on who e lopes it opens. The Clifton channel ends in the forest west of Allyn, 160 feet above tide, corresponding with the dominant water plane of Lake Ru sell. Tm;; B:aINNO DELTA. Tl1e only delta of Vashon age known in the valley of Hoods Canal i at the mouth of the Dusewallips River, on the north ide of the valley. (See Fig. IS.) At the seaward upper margjn, it is 120 feet above the Sound. Its surface .is a plane, sloping toward the trough of Hoods Canal. Its altitude make it obviou, ly a feature produ ed subsequent to Lake Hood, whose waters were 100 feet higher. THE PouLsJJo C.IIANNEL. T.he Kitsap County peninsula be tween Hood Canal and .Admiralty Inlet i sufficiently high to have confined Lake Hood a far north as .B1·eidablik, northwest of Dogfish (Liberty) Bay. A meridional trough of the pre Vashon topography, styled the Poul bo Valley in thi paper, cros e the peninsula here Dogfish Bay gring in the southern portion. A wampy col occurs midway of its length at an alti tude of 1~0 feet and a stream t errace lie on the eastern side of the valley near the col, at an altitude o:£ 150 feet. Other FIG. 12. Le:ke IIooa, Glacial Lake Snmmamlsb B.Dd Lake .Russell. CbnUJJele and Deltas or th.ls stRge 11.re ttoseb.ntcheil. 148 Bulletin No. 8, TI a.shington Geological Survey terrace I po ibl of tbc am g ne i occur at 190 and ~~5 feet. There i evidence here of con ·dernble tream ero ion in the Poul ho Valle which can be con i ently correlated with data already pre ented on the glo.cial lake hi tory of Puget ound. In the Poul ho , alley, Lake Hood appear to ba e found an outlet. lower than the Iifton channel and to have ent red Lake Ru ell a the head of Dogfi h Bay 11orth of th latitude of eat tle. (Fig. 16.) The liO-foot col and the 150-foot terrace l'ecord the snme change of 1 vel that are found along the Per cival Creek chann 1. The B1·inn011 Delta is to be corre1ated with the UO-foot lev 1 of Lake Ru ell. The two lakes may be con idered as one u.t this stage, Lake load inking by cro ion of the Ponlsbo channel to the level of Lake Ru ell and be coming e.n arrn of it. If tbe ice dam cau ing Lake Ru ell re mained effective during the next few mile of retreat a there is good rea on for belie ing Lake Russell levels obtained in Hoods Canal with broad connection aero s the low northern tip of Kit ap aunty penin ula a few mile north of the Poul bo channel. Lacx OF VASHo:N DELTAS OF OLYMPIC Rrv:r.Rs. everal vig- orou. tream enter Rood · anal from the Olympic Mountain and a.re depo iting actively in the ound today; but th il' valleys have no delta at the level of the glacial lake . he valley of Quilcene River ha o. long gra el lope gradu ally descending from altitudes above Lake Russell to tidewater. Fore et bedding exi t in this gravel and the urface is ter raced, but no definite delta. 1 vel have been recognized. The Duckabush Valley ha a long terrace on the nortl, side evi dently aggraded to level higher th11n those of the wat · in the Canal now, but falling below the leve1 of Lake Ru ell at its lower end. The valley of th Harna Rama and kokomi h rivers are den ely wooded where Ya hon deltas hould exi t. Though ome labm·iou earch on tbe fore ted floodplain and adjacent slopes ha been made no d lta of the~e tream re f ruble to th glacial luke have- been found. PRESENT DELTA Fro. 13. 'Che Brlnnon ~lta at the Moul.h ot t.be Du •waJUp Bl r. A rock ledge OOCUl'll at the l"Onstrletlim tndJcnt ~. ancl bas "ll<'t<'nd d'' I.hr mtlng portion ot tbl' orlglnJl.l deltL Ura... ,, from hart 6l3U or I.be • S. C. & G. . 150 Bulletin, No. 8, Washington Geological wrvey It cannot be considered a eriou objection to the interpreta tion ad anced that deltas have not b en found at the mouth of all entering river . Sub equent stream ro i n ha appar ently regraded the late Pl 1. tocene gravel of bvo of the e val ley . The other two have not been ufficiently tudied to make it certain that no uch delta ex.i t though if thi i true it will not b trange. • GL C L LAKE S,\l\IMA1,U:SH. The hough occupied by thi ancient lnke is parallel to and ea t 0£ that containing Lake Wa bington. It is about !S mile long and has an average width of three-fourths of a mile. It deepen gradually outhward to its abrupt termination by .tluee rock hill 1 500 fl 000 and S 000 feet above tide near I sa.quah. The ea tern of the two pa e leading south from the valley is 315 feet high and the we tern one is between 350 and 400 feet high. (See Fig. H for a g1·aphic repre entation of the history of thi lake.) Fn T TAG"E. Ea t of I aquah on the northern flank .of Mount I aqua]1, the highest of the three rock hills i a con siderable level area at an altitude of 4i5 feet more than 300 feet above the floor of the trough. Back from the margin the terrace 1·i e 20 feet higher and has a still more exten ive le.vel area continuing eastward. On the southern margin of thi high-level gravel depo it are imperfect terrace a hlgh a 465 feet. At the we tern foot of this plateau gravel spread, out widely on the valley Boor in terraces 215, 195, 175, 160 and 120 feet above tide. The ea t fork of I aquab Creek cuts the gravel plateau to a depth of 300 feet, and sections in the gorge how stream rolled glacial gravel i.n bed of variable positions, indicative of hifting current with considerable variation in velocity. No true delta structure was seen. • The remnant ot a Vashon delta ln the Dusewalllps Valley ls pre served only l.>Y an outcrop of roek at its bead ln the manner of a. "defended" terrace o! alluvium. (See Fig. 13.) Glaciation of the P·ugct Sownd Region 161 The grade of the Ea t Fork of Is aquab Creek fl5cends rap idly ea tward until at High Point the creek i no longer ru hlng a.long the bottom of a narrow gorge but wandering th.rough a wide flat-bottom d, swampy valley, in which the shea.m ap pears focongruou ly mall and inelre ti e. Two mile ea t of High Point, thi old floor uddenly nds at 540 fe t above tide, with the valley at full width. There i a de cent here of about 100 feet to Raging River which come. in from the outheast and turns northward at thi point. Rep1·e ented b terraces, the old valley floor continues up the volley of Raging River for four or five miles , here the grade of the latter ha risen to the level of th old floor. Fragmentary terraces along Sno qualmi River, between the Fall and the junction with Raging R iver, and along this river between the jUJ1ction and Preston, indicate that the e stream formerly united at Pre ton, and that their combined water built the Issaquah depo it. t the time of thi gravel deposit, the e ca.ping water of these river wa held back, probabl by an ice tongue in the am mami b 1'alley which dnmmed the tream where the depo it now lie . The col in the two pa e among the hill termin nating the San1ruo.mi h trough at the south are too low to have ca.used the ponded water in which the I aquah gravels were la.id down. Thi , hardly to be con 'dered a n lake de posit i the olde t record of glacial water in the ammami h Valley. The di charge of the Snoqualmie River through the Preston-I aqaali volley was cau ed by ice blockade of the more northern and lowel' route followed later by that stream. SECOND STAO-E. A gia iul lake of limited extent mu t have formed in the southern porti n of the ammo.mi h Valley a little after d po itioo of the I nquah gravel . Di charge from this 1 lake wn outh, Md through the two rock-walled valle , bo1h of w-hich are floored with coar e tream gravel the etuitem on carrying the larger amount of water and for the longer time. A channel exist a.eras the till 1·idge between Lakes W a.sb igton and armnarru h at the north ba e of ewcastle Hill, the lowest of the three rock hill de. cribed. It altitude is some- ~ "Roc.K Hills §} Issaquah Gra"els ondl?edmond Delta Gl~cial Droinai;;ie Channels ~ Ground Moro,ne D ancl G\ociol Lal ll't G. 14. Map Showlog Prloclpnl Event's in the E!lstor_y of Glaclal Lake Sammamlsh. WMIUl:Sll'fON (;1,:0LOOl{".H, SPll\°"P.\' Fw. 1. Distorled Admirally Sediments, J\icNeil's rsland. Fw. 2. Structure o( the Quatsap Polnl Deltu Beds. Glaciation of the Puget , hat bo,·e 500 fe ul.i v ti e. It i 6 or d ll'ith c r gr v . n ll1cr ehannel nt , liahtl low .r nltitude exi t n mile far her nor~ alon h Line of Phant 111 nod Lar n lak both of these lyio iu ,, J finit cLann~I wu n.nd a half uiiJe long tlcro s the ridg . uthwnrd di char from the aouru.iJiii ·Ji alley betwe u tJ1 hill. TmlilJ T .\GE. i::o.:.mND ELTA. Th r ,uc terrnC<' in I I -uqut1h gnwel dep ~it nt nl itud •lwe •n 215 Rnd l O fo t low •r than any out I •t cbu.nncl thu f1 r rl · · ·rib d for h\ciril Lak • Smn11mrni. h. '1 h ir ri in will b h ·tt r under t.o I 11ft r elta. l the north eud f th pre ent hlke 11nd no the ea. t . id • of all her i u d<' o it of tr tun g nv ·I· hich hn!> b en re tud than any otl r featur of the enti1· r gion. alled th R crlmo11d Delta. 154 Bulletin No. 8, Was11ingto,n, Geological S·urvey East of Redmond, a considerable trough from the nortb unites with the Sammami h depre ion. In common with the majority of valley in the region it i of pre-Va hon age, not the product of postglac-ial erosion. Depo ition by streams has produced a fairly level floor in thi alley, the altitude near the mouth being 50 feet abo e tide. Southeast of this alluvial plain a semicircular scarp ri es abruptly. It is convex tow-a rd the pla:in, and faces we t, north and east. It is a conspicuous feature from the valley floor wherever the view i unobstructed. Its ba e line is nearly hori zontal and about 50 feet above tide. Its summit profile .i made up of four levels at UO, 130, 140 and 160 feet re pectively. On examination, the carp i found to be compo ed of coarse gravel everywhere di posed almo t a teeply as they will lie. On reaching the top., level terraces of coarse gravel are seen stretching back at the several altitudes noted, covering about a square mile. The 160-foot area is be mo t exten ive and lie in the outh and we t portion of the de o it. The nor h and northea t ide are made by the UlO- and 1SO-foot ter races. con iderable portion of the ea t ide i broken 11,Jld inegular from the pre enee of two large rouabJ linear ket tles. The lack of a teep de cent a.long much of the a t ide is due, probably to bw1cl1ed kettle along that edge. On the south, the 160-foot terrace abuts again t higher till hill . Th e relation are hown in Fig. 15. Evans Creek a.pproache Lake Sam.ma.mi h from the ea t, the Redmond Delta lying in tbe direct continuation of its upper course. The tream make a detour to the north to pass around the delta". and reach the lake. I ri es in a mar hy col in a wide valley which e..~tend. outhea twa:rd for 11 mile from the R ed mond De.1ta to the present noqualmie River valley. The broad floor at tl1e col i 160 feet in altitude, and two splendidly de veloped river tenace betw en the col and the delta are 140 and 200 feet above tide. East of the col, fragmentary ter race continue the a cending profile of the old floor ea tward Ii] Delta Area ~ Hig\ierAreas O Vl:l\ley Bottom PIG. 111. Tbe llf!dmonll elta ud Environs. eltn Brea do1t.c Is aqunh, pa ed through the pre-Ya 110n aJley to Bothell by which the two parallel le.kc arc connected toda at the north. T]1 160- flJld 1~0-foot ter.race of the Redmond Delta, with short, open channels connecting GlAcial L ke ammamish with Lake Wa hington Vall indicate tlll:'i:t thi third tage of the local Jake, recorded by the Redmol'ld Delta, is really a portion of Lake Bus ell' hi tory. Glacial retreat by this fone had allowed the norlhwa1·d-extending water of the ma ter lake to occupy the Lake a hington trough and to control the later static ·water record in the Sammami h Valley. LAKE NOHO:MISR, The old noqualrrue River channel now occupied hy Evan and .Patter on creek leading to the Redmond Delta, docs not con inue unintcnupt dly up into the a cade founto.in . It breaks off abntpt:ly on reachiug the pre ent noqualmie Val ley which i mu h Jo,ver in the ame fa bion that the old val le east of High Point break off at Pre tm,, except that in the present case, sub equ n ero ion b Patter on reek ha 1 rgely de tro. ed the a tern portion of the old tr am floor, and it is really a prnjected profile wbfob i abruptly termiuated. noqualmie River i fl.owing in a trough va!Jey of .inter glacial ero ion which lies arall 1 to and ea t of, the Sammam i h Valle and i open to Pl1get ound at it norlhern end. The abrupt d cent which take place at the ea t end of the projected profile up the rnlley of E ,·001s and Patter on creek to the pr cut noqualmie River alle thu i not the work of postgla ial ero ion, a it is at Pre ton. n the contrary pond ed water mu t have fiU d thi rnlley to the height ol the trun cated profile in order to flow we tward acros the divide to the Redmond Delta. Thi water con tituted Lake 111ohomish. (Fig . 14 and 16.) Few definite data can he pre ent d concerning tl1is lake. Its altitude wa about 250 feet when di charginrr to the Redmond Delta. Earlier outlet channels to Glacial Lake runmami h oc cur parallel to the Evan -Patterson C1·eek cl1annel and south B'10. 16. L1tke Snohomlah s.nd Lllkl! Ru ell, at mru:lmum extent ot 100-toot stnge. ChllD nels a.nd Deltas ot tbls Btage o.re ci:os hatched. GLaci.atian of the Puget Sound Region 169 of it, but their altitudes are unknown. It appear probable that this lake backed up at it higher tages to the foot of Snoqualmie Falls into which that cataract plunged. The lake extended northmird a long di ta.nee, perhap nearly to Everett, but apparently never ank to the level of Lake Russell. HlSTORY OF LATI;:11, LAKE RUSSELL. The retreat which de troyed Lake isqually and allowed the re-formation of Lake Rus ell early cleared the Narrow and brought about the destruction of Lake Tacoma aJ o. Lake Russell then extend d ea t and outh up the Puyallup trough, and north into the White River trough where the uburn Delta of Lake Tacoma records the earlier presence of tand.ing waler. The Hrunmer ley Inlet arm of lie lake originated oon after ward, and the helton Delta was then formed. Lake Skokomish quickly pas ed through it brief history and Lake Hood be gan wh n the Clifton outlet came into existence. Its 1 vel persi ted while the glacier retreated for a di ta.nee of lil6 miles. Du.ring th.is time, the channel of the Clifton outlet wa cut to a depth of 60 feet, but at the time it w~s abandoued its grade was still 25-50 feet to the mile. A rapid retreat for the foe for the length of Lake Hood i thu. indicated el e the grade of the outlet would have teen reduced to a lower slope. The opening of the Poul ho channel records the pre ence of the 160--foot level of Lake Russell in Dogfish Bay, and con equently in the great trough of Admiralty Inlet as far north as this latitude. Presumably the hi tory of Glacial Lake Sammami h and Lake Snohomi h was being enacted contemporaneou ly with that of Lake Hood. Both Glacial Lake runmami h and Lake Hood becnme 11 part of Lake Ru ell before the Percival Creek channel to Black Lal,e outlet had lowered the master lake to the UO-foot level. THE RrclU\ioNn D:nu. Fo-r rnore than a mile south of Richmond the bluff of dmi1·alty lulet are compo ed largely of fresh , n hon gm vel, with a hon ti.11 u ually e11.-po ed be- 160 B'll,lletin No. 8, Washington Geological Survey neath. Foreset truabue i to be r ognized in e ea cliff despite the loo e character of the rnate1·ial though the opening of a lp.rge pit by the Enamel Bri k and oncrete ompany offer the be t opportunity for tucly of the gr1wel. Fredomi nan.ce of for et tructure (Pl. . I Fig. i) immediately recall the pit .in the teilacoom and Seq'llali~hew Deltas. The re- emblance i complete, excep that thei·e i no econd s t of fore et beds above the top et. The altitude of the upper plane of the e delta stra.ta i 165 feet above the adj a nt ound. At U1e head of th pit topset b d are flO fe t thick. Back from the edge of the pit the urface i plane, 1·i ing from 185 to 200 feet in half a mile Ol' o to the lop of higher hills. breached kettle in the face. of tbe delta south of the pit interrupts the continuity of the bluff. '.rhe bottom of the kettle be1J.rs no gravel, and the ice block mu t have come to the m'face of the delta, or even projected above when the "'ravel wa depo it cl, and must have remained until depo ition cea ed. Another kettle 60 feet deep and with an frregular form lie back in the plain, tl1e ea.ward face of the delta being wiaffected by it. A narrow elongated depo it uch a the Richmond D elta with the trough of dmiralty Inlet on one ide, and ground morajne on the othe1· higher than the agO'raded plain can find explanation only .in the a umption that ice wa pres nt in the great trough at be time ot delta growth an formed the retaining wall which ha nmv vanished. ( ee figuTe l '7.) The p1·e ence of the kettles corroborate thi hypothe i . The fore e b cl dip we twud ho, ev r, at right angle to the lengtl1 of the delta. The stream which depo .ited the gravels wa confined to a southward cour e between highe1· urface of ice on the we and earth on the ea t. On reaching tbe begin ning of the curv of the ice front in~ dmfra.lty I nlet, the stream tumed abruptl westmud to the trough. the ice front with drew along the mile where the delta QOW exi t tl1i procedure of the tream was ontinned the de1ta depo it growing noJ'th ward a the ice rctr ated and he fore et bed dipping wesbv:ud throughout. The nortJ1ern portion of the d ]ta therefore is Cole Point. And r on I land. A a <'.llll" or .\()1ulrt1lh.' ond. Glaciati \ / _/ F10. li. Relal:lo.o. O! I.I.I tllrbmond lea to IAll flu 11ell ftild th •11 tit owul lnclcr. treo.m-cut bluffs s pn:rate nnd the surfo e becomes brok n nnd moraini . In thi di tun c the channel floor ri ·e gradually from the ltitude of the delta plll.in to 340 feet. Lit c ting d t ii· f the head of the channel io the mora.inic ll'l\ct ha,·e been , orked out, but pace cannot be given for thei1· r entation. uftice it to y th t th treum here originnt d 1\ tl1e glacier fton -6 16! Bulletin No. 8 Waslmi,gton Geological urtJey and flowed a mile or so before entering Lake Rw,sell. Its be havior was imHar to that of tb tream which built tl1e Tacoma Delta. The edge of the ice over he pre-Va.$bon ridge which is par allel to Admiralty Inlet on the ea t, apparently la but a mile or so north of that in the inlet, though the ridge bere is 400 feet above the ound and t.be Point Jefferson Deep (Pl. XXIV) 918 feet below ea level lie directly off the delta face, It would be expected that 'll1i relief would cause the ice in the trouo-h to linger long after the bill had been bared and thu produce a notably fingered margin to the glacier. THE HlO-FooT LE,'EL OF LAKE R SELL. The Richmond De]ta e tabli lie the presence of the 160-foot tage of Lake Ru ell a far north a.s tl1e latitude of Richmond ( ig. 6). It prove that Lake Hood sank to tbi ta.ge when the Poulsbo hanne1 came into u e and e tabli he the fact of a broad con nection at the 160-foot level between the ammanri h and Lake Wahington trough through the pre-Va hon valley at Bothell. The front of the glacier retreated and the Richmond Delta wa abandoned by tJ1e gla ial river before the lake ank to UO feet. Yet a retreat of the ice front of but a few mile from the Richmond Delta would have allowed open connection between Hoods Canal and dmiraJty Inlet, and the Poulsbo channel never would have been eroded to the UO-foot level. It i therefore evi dent that Lake Ru ell wa lowered to the liO-foot level immedi ately after the Richmond Delta was made and that a con ider able pa.u e of the r treating glacier f:ront ju north of the delta was nece ary to hold Lake Hood to the Poul bo channel, until it likewi e had been lowered to UO feet. The Brinnon Delta and the lowest portions of the Sherlock Delta and the Redmond Delta are tream deposits in Lake Ru - ell when it surface wa 120 feet above ea level TRE NonTHE1lN LIMIT OF LAla;: Russ:ELL. It i probable that a definite northern limit of Lake Russell will never be de termined. Evidences of t.he lake' ex:i tence are cattered, and a continuou record, uch as a hare line i required to e tabli h Glaciation of the Puget Sown.d Region 169 a definite margin. 'l'be limit cnn be di·awn however, fo the form of an ea t and \ e t zone at th north end of the lak north of the outhern edge f which the ice undoubtedly retTeated, and beyon the northern edge of which it never retrea.ted during the lake exi t.ence. The .outhern edge of uch a zone is dra,wn ju t north of the Richmond Delta. The northern edge may be drawn through the city of Ever tt for the following rea on : (1) The nohomish trough wbi ·h contained Lake no homi h and now i u ed by the Snoqualmie River for mo t f :its length i open to Admiralty Inlet only at Everett. It one other openfog i the Evan -Patter on Creek channel, the outlet of Lake Snohomi h the u e of which built the Redmond Delta.. The exi tence of the UO-foot level in the Redmond Dclta. proves that the glacier retreated from the 160-foot Richmond Delta and that the lowe t tag of Lake Rus ell wa foaugurated before the Redmond Delta, the product of the outlet of Lake Snohomish was completed. In other words, L11ke nol1omisb did not hare in the 120-foot level because the glacier front till la uth of • ver tt where open connection ex:i ts with the trough of Admiralty Inlet. ( ee • ig. 16.) (2) The Pilchuck River, which nter the nol1omi h trough at the town of nohomi b (Pl. XXII), carried also the waters of the outh Fork of the Stilagu111ru h River for a time du1·ing glacial retreat. Condition thu were favorable apparently for the formation of a delta in the noh mi h trough~ and a channel fioor ndju ted to it level. Since no trace of either has been found but in tbei1· place i a glacial river valley ;vho e floor is clo e to pre ent ba e level, it i evident that no ponded water near Lake Ru ell Jevel exi ted in the Snohomi h alley when the region north of Snohomish and Eve.rt-tt wa bared by glacial retreat. Failur of the ice dam which had held up Lake Russell and ih tributary lakes, i thus indicnted to have occurred while the glacial margin wa omewhere between Richmond and Everett. LACK OF VAS RON DELTA OF Tl!E CASCADE RIVERS. a med in order from south to north, the Puyallup White, Green, Cedar, 164 Bulletin No. 8, Wa,11iington Geological Sur'Vey and Snoqualmie ( outlet of Lake Snohomish) river entered Lake Russell from the a cade Mountain . Only one of these po - sesses a delta built into that lake. The Puyallup Ri er ha. aggraded it trough o largely in the viciruty of Orting that the valley floor now lie above the level of Lake Ru ell. Any former delta that may ha e ex i ted at tho e levels is of cour e completely concealed. lite and Green river enter the meridional White River trough but two or three mile from ea.cl1 other. Po t-glacial depo ition ha. form d a wide plain here about 100 feet above ea level, on which the river meander in con tantly shifting cour e • White River ha divided until recently into two dis t.ributarie ; one, tuck River flowing to the Puyallup a.nd thence to ommenccment Bay at Tacoma. the other continuing north to Elliott Bay a.t eattle. Though Green Ri er made ad ltn in Lake Tacoma no trace of a delta made by either of the e tream in Lake Ru ell ha been found. A ufficient rea on may exist in the meandering behavior of the e river which ea ily could have d tro ed such formei· depo its. The Auburn el.ta, or ucb pa.rt of it as re mains ha been pa1·ed because of its location at the tip of the divide between the two treams. No d lta made by edar River in Lake Ru ell remains, but gravel pits on both ides of the valley at Renton, where it en ters the Lake Wa hington trough, expo e fore et beds dipping down tream and lying against the higher till-covered slope . Their altitude f 1l a little below Lake Ru sell level but the upper portion of the delta which would how contact of foreset nnd top et beds ha een removed by ero ion. The e foreset trata may be interpreted confidently a the remnant of a delta of edax Riv in Lake Russell the main ma of the de po it having been de troyed by lateral planation of the river during po t-Va hon time. LAcK. OF aonE LmE ,u n EDtMENT OF LA.ll Rus ELL. The narrow land-locked arm of Lake Ru ell were not favor able for the development of v.er. effective , aves such a would Glaciation of tlte Puget Sownd Region 165 produce la ting result in a comparatively hort time. The bluff a.re generally o steep that, were ea cliff's and wave-cut terrace once developed, the clumce for escape from de truction by ubsequent sliding, or by Wt\\'e undercutting at the present ea level, , hich has exi t d much longer than did Lake Russell, would be small. ,nder uch circum tance • no attempt will b made to co1Telate the few doubtful old shore records lying high on the Puget SoUIJd bluff which might e a cribed to the glacial lake . For the rea on that Pun- t ound at pre ent occupie roo t of the area covered by La.ke Ru el4 and other portion once occupied by the lake are now covered by fre h-wate.r lake or r cent alluvium few occurrences of sediments of tbi lake can be expected. And becau e, ub equent to the lake's exi tence, the ba in wa even more deeply submcrg d, hhi time beneath tbe ea unfo iliforou s dim nt • found ovedying Va hon till below the former lake level cannot be uohe ib1tingly referred to Lake Ru sell. One area only Jia1, been found where a lny and and deposit without much qu tion may e ref ned to deposition in Lake Rus eU. This i a few mile northeast of lympia, near] north of Lacy. The area j ~ n pitted plain gradmg laternll into ground moraine on all ide . The dcpo it is composed of fine sand and clay practically free from gravel and affotd an ex llent oil. The area now i largely cleared nnd culti vated while adjoining surface of ground moraine are tiD i.11 fore t or have a few trnggling or abandone !arm . It i worthy of note in this conne tion, that till from the adjacent ground moraine has been n ed on tbe road of thi tract with remarkable ucccss a urfacing ten yea1·. old being today in a nti fa tory ondition even in the rainy winter • K ME T.e.&11.ACE • Kame terrace form a prominent feature of the modjfied drift of the Puget ound country. The were fir, t identified in the region and have beeu de cribed in the Ta oma quadrangle by illi , They have been found by the writer to be abundant on the eatt1e quadrangle immediately 166 Bulletiln, No. 8 Washmgton Geological Surney north of the former. in e kame teuaces are the product of stream with ice pa ively cooperating the should be expected to terminate wherever th depo iting tream entered t&nding water. And if the water of Lake Ru ell e.Tiended northward into all the trough which were sufI:icientl low a the fingers of ice hxa.nk within the valley. 1 karoe terra.ces hou]d be com pletely lacking below the l vel of that lake. No ka.roe terrace of the region are known below the 160-foot contour. everal well develop d tena e end at about thi level, and the topogrnph of the gra el becomes very subdued whe1·e the de.po it i continued farther uown the valley. oi:th Greek .flowing into Lake W a hington near Bothell has a karne terrace be mile long which nt an altitude of about !200 feet behaves a described above. From Bitter Lake to Green Lake in the northern part of eatt1e, i a large kame terrace which di appears beneath the la ter body in a peninsula heavily covered with gravel reappear beyond the lake and continue down the general trough toward Lake Union. It de cends be- low 160 feet in a short distanc south of Green Lake, its char acter changing at thi point to tl1at of a water-laid depo it, and it mass dimini hing notably. ther instance of the ame character might b cit d but the e two illu trate he di tribution and behavior of li:ame terrace ufficiently to how their bearing on the existence of Lake Ru ell. The pre ence of tanding water in the e valleyi; at the altitude of 160 feet i reco1·ded by the failure of kame terrace to extend below tb.i altitude. Ull.AINA.G-E '.l\IODIFIC TJ.O OF TH:E 8T1LAGUAM1SH lUVEl\, The earlie t expo ed part of the tilaguarnj. h River valley wa the South Fork which emerges from the Ca cade Moun. tams on the drHt plain at Granite Fall . The river now fl.ow eight miles north before j oin.ing the 01·th Fork; but when fir t expo ed. by glacial retreat it water were turned south ward into Pilcbuck River, a tributary of the Snohomish. At Granite Falls little more than n mile of low land sepuates the two stream . ( See Plate XXII.) Glaciation of the Puget Sownd Regi-071. 167 When retreat of the ice had progl' sed sufficiently to fr e the valley of the North Fo1·k, the two stream joined at .Ar lington and flowed south throu"'h the broad. interglacial Mary ville Valley to Port Gardner at he town of Mary ·ue. 'l'his valley wa filled to AD unknown depth with nnd and gravel Fra. 18. Vicinity ot rllllgtoo lllld lltnrysvllle, which now con titutc a plaiu about three mile wide by nine miles long de cending 145 feet from A1·lington to Mary ville a grade of 15 feet to the mile. ( ee Fig. 18.) The urface in the vicjnity of Arlington i strongly terraced The town i built on two benche both compo ed of gravel to their ba e. The bu ine portion is on lhe lower bench llO 168 Bulletin No. 8, Washing-ton Geological urvey feet above tide, and the residence pol"tion i on the higher bench at an alti ude of 160 fe t. umerou pit and street cut expo e the material which i tumultuou ly tream-bedded in botl1. The upper terra<.'e correspond with one aero the ri er to the north. Bot) are obviou ly r mn I'll of a valley trajn which cam down the North Fork alley from the Ca. cade l\Iountain . The 110-foot terrnce at Arlington i too low to belong to drainage wbjch flowed southward from Arlington to Mary - ville. It as formed by the firt drnina e whlcb flow west ward along the pre ent com e of the Stilaguami h River from Arlington to Stfmwood. Thi later route ~ as blo ked by the r treating glacier 11t the time the Arlington-Mar Vllle valley train l\'a formed, but when opened pro, ed to be the lower and ha held po tglacie.l drainage to it OUT e. Ero ion in development of the present route west from Ar lington ha e."'<'.po. ed a section of the filling of the far , ville Valley at its northern end. Thi i compo d entirely of and and ravel to a. depth of 50 fe t. rond cut in one pince expo es a great deal of pumice and volcanic and or a h in tennce cor.re paneling to the 110-foot .rlington bench. The Stilaauamish quadrtmgl ea t of the a.rea. di en ed in the present pap , how ome int r ting dr inage chanae which make j e,rident that the auk uia.ttle and Skagit River formedy fl.ow out on th drift plain of Pug t ound at lington, and contributed to the formation of th Arlincr ton-Mary vme valley train. From the til guami h quad r ngle tl1e vall y train con be trnced up the orth •ork valley to Darrington with a orade of abou 16 feet to the mile. Big Lake and M •1\1ul'l'ay ;Lak lie in a no1·th and south al- ley in the diagoMl . pur of the ca.de Mountain which jut out into the drift plain north of .A.rlington. The valley at Big L ke i floored with till. No glacial tream passed through the valley, thouc,,h the till i di po ed on the lower lope in huge :fluting and furrow that r mble the tenac of a grav l train. -- LA. KE. PU'tALL UP--, !.SOtOHOP) LA.KE. PUY ALLUP 400 tCLOVlJH .R.) I LAKE SKOKOMISM 3SO ' EARLY LAl LA )If. HOOD ?ZO I LAt HORTH F>R'E.5ENT t1ARIN~ OCC.IJPA.NtY SO UTH 10. 19. ProOles o! lbe Glaalal Lli'kes o! Puget Sound, proJtcted on a North o.nd South I'lanr. Position of outlet In the plnnc 11hown by the abort vertical line 11tto.cbed lo encll proOle. ne.Jnllve nllltuf.lcs, lengths, and laUtu!llna.l p09ttlona B.bOW'D, tbe latmr corrupoudln g rougbl7 to I.be sc.que.nOD o! lalre formaUon. 170 Bulletin No. 8, Washington Geological Swrvey A glacial lake occupied the valley now containing both Big Lake and McMun-ay Lake, and had its outlet southward to Pilcbuck Creek, a tributai:y of the Stillaguamish below Arling ton. This stream is to be distinguished from the Pilchuck which flows to the Snohomish River. The divide in the old channel toda-y is just south of McMurray Lake, and about 250 feet high. A long glacial d.rai-nage channel leads south from it to the village of Pilchuck where postglacial erosion has ob scured the outlet. The two lakes now drain northward to the Skagit River. The ice dam held up a glacial lake probably eight miles long north of the divide, and tm·ned its drainage to the Stilnguamish. A lower spillway appears to have been used for a. brief time across the drift pin.in to the vicinity of Mount Vernon before final disappearance of the lake. GLAClaL LAKE WHATCOM. Lake Whatcom occupies the valley of a northward-flowing stream of pre-Vashon age, eroded in the northern slope of the diagonal mountain spur of the basin. The retreating Vashon glacier left a heavy moraine deposit in the mouth of this valley, causing the present lake. There are two b1·oad drift-filled valleys opening northward to the low plain of Wbatcom County from the northern end of the lake. They are separated by Squalicum Mount.run. Either of them is oriented favorably for the continuation of the preglacial valley, but without data on the depths of drift in them, the question cannot be settled. The lake extends farther into tbe western valley and discharges through it. Whatcom Creek, carrying the outfl.ow, crosses bed rock close to the lake, but is so far over to one side of the filled valley that the rock in the stream bed is probably only a portion of the preglacial valley slope on which the stream has been super posed. During the retreat of the Vashon ice across this region the glacial front formed a dam too high for northward Bow and glacial Lake Whatcom was formed, with discharge from the Glaciation of the Puget Sownd Region 171 southeast tip to a tributary of Samish River. The col in the outlet valley lies just north of Mirro1· Lake at an altitude of 375 feet. A drift filling here has been incised to a depth of SO feet. The valley which canied di charge of the glacial lake unites with a larger one at Wickersham. High terra.ce of glacial gravel occur in thjs larger valley. At :Prairie, three mile outb of Wicker ham, these terraces are S4!0 fe t in a1titude and farther south of here the widen out into a broad plain which lead to the kagit River. This train which floor the valley to which Glacial Lake Whatcom di charged came down the main valley from the north. Its extent north of Wickersham ha not been studied. After the margin of the ice had withdrawn from qualicum Mountain, and after Glacial Lake Whatcom had ceased to dis charge over the Mirror Lake col, the gravel train wa largely eroded by the diverted South Fo1·k of the ooksalt River, which for some time after the di appearance of Glacial Lake What com, was blocked by ice at the north and forced to be tn'bot&ry to the Skagit. It course at thi time was southwest from Prairie to the present Sam.ish emerging on the Skagit Delta three miles north of Burlington. At the inception of standing water at the south end of Lake Whatcom valley, the southwestern arm contained a mall in dependent lake with outlet to Sami h River about three mile below Sa.mi h Lake. The outle ch1,i.nnel lies on the north side of the drift-filled vaUey connecting th Whatcom and a.mi b valleys, with an altitude of about 415 feet. t LAK--r-E. PUYALLUP S50 (OI-IOP OUTLE.1) LAKE PUYALLU P ,400 (CLOVER CREEK OUTLE..T) LAKE SKOKOMISH 350 E.ARLY LAKE TACOMA 320 1 LAKE 'oAMMAl'IISH 300 LAKE SNOHOMISH· 250 L0AKE TACOMA ?35 LAKE HOOD ?20 LAKE NISQUALt'I 180 LAKE RUSSELL 160 I LAKE. RUSSELL 1?0 WE ST ------'P-'R~E=-S=-E=-N;...;..;.T_M....;A....;R~l~N....;;E.;...... ;;0...;C;.:C....;U_P....;A.;.;.N_C;;.Y;...______EAST Fro. 20. Prolllc of th GlacJ&I Lll.kes of Pugl!t und, proJ cied on no o&t and west plane looklng north. rosltlon ot Olltlct l.n th plan shown by short vertlCJll line attach d o eacb proOle. Rolntlv altitudes ond longltudl.Dal poaltlon, lllld l.'Tco~st ca t aod west extents ebown. Tbc grou])l.ug sho\VS tho eastern or Cascade side of the bas1D to bnvo b.ad lbu more varied bJstory. CHAPTE ll. THE ADMIB.ALT L IATIO . YNOP lS. TB.E \J) UJ1ALT\' TILL. GnE PomT • .HA.RTSTE "£ Js~ro. DENNY Hn.L. Po 10 • HEAD, GE:t-.'ER~ IIARACT.ER. THE AD illlALTY EDD\I:ENT • GENERAL DESCRIPTION. T NIN(; AN.D D:i:: AY OF THE ADMIRALTY .EDIMENT • VEGET L REMAINS. ANIMAL RE u.ws. INTERCALATED Tn.L. THE IN TBE ADMIRALTY EDllCENT • GENESIS OF TJJB ADMIRALTY EDIMENT • UMMAllY OF THE CSA.PTfilL, THE ADMIRALTY TILL. The hi tory of glaciation in uget ound preceding the Va hon ep ch i "ery meager in detail nd probably al ays will remain o. The cover of a hon till and outwa h in the Puget ound ba in i almo t complete. Drift older thao the Va hon i po d only in excavation in tream bluff and in the ea cliff along the bore of the ound. In uch ituations the Va hon till Ji almo t everywher on ta.in d und weathered strat ified drift of con id rnble thi kn . ' his tratin.cd material j known in a f w place to re t on an older till heet, named the Admiralty 1'ill by Willis. GR.EE.,; POINT, .Admir lty Rnd \ a boo · Rre rpo d in the ame sea cliff in a few in tanc the e aft'ording exceptional opportunity for 174 Bulletin No. 8, Waal1,ingtrm Geological Survey the compa1·ison of the two till . The cliff at Green Point be tween Hales Pas age and C~rrs Inlet (Hender on Bay) show.s both tills, with brO\v:n-stained sand between the and consti tuting probably only a part of the tratified drift eries. The two tills are ery imilar in olor composition, degree of con solidation, ue, abundance and -rounding of pebble ab ence of bowlder , etc. Both are gray, the Va hon till being some what lighter. KAltTSTENE ISLA.ND. Both till , separated by ained ediments, are hown on the ea tern ide of Hartstene I land. o greo.t dilrerence in the two till is to be detected, the Admiralty being , eathered or stained near its uppet' urface, and the Vashon being lighter gray throughout. The Admiralty till here may contain a slightly larger proportion of pebbles tban the Va hon till, and they are somewhat more angular. DENN'Y RILL. In the Denny Hill regrade of the city of Seattle a hill com po ed largely of dmi ·alt sediments wa removed by hydraulic methods from more than twenty city blocks the maximum cut being Hl5 feet. (See plate XIV XV Fig. S and VI.) Va bon till capped and ven ered the hill with an average thickness of 10 feet, and Admiralty till was e..xposed in the deepest sluiceways on Bell treet. The only difference between the two tills thus clo ely jtL"l::tapos d was (1) the omewhat weathered condition of the upper portion of the Vashon till involving a difference in color, and (2) the greater consolidation of the lower till. l'OSSES 10:N RlllAD, Rus ell, \ ho f.irst recognized the exi tence 0£ two till beets in the Puget Sound basin, cite Po e ion Head, at the outh end of Whidby Island, a e.xhibjting the two tills eparated by "medial' ands, gravels and lignite. The writer bas found Pos se ion Head to show three di tinct till stu,ta eparated by tained sediments. There i little difference among the till , each being gray in color, and compo ed apparently of fre h Glaciatio-n of the Puge.t Sownd ReguM, 175 aterial. The upper urface of each i somewhat stained. The lignite beds J:eported by Rtt sell lie in the ediment b tween the upper and middle till·. '!'Ile. lowe·t, who e ba e i below bigh tide contain many pockets and lenses of gravel, the presence of which may explain hy Ru ell did not recognize it as a till. The Posse sion Head section i not closely pa1·alleled in Puget ound. It ugge tion of three glnciation , the till of the oldest being apparently a fresh a that of the younge t is not borne out by a study of the sea cliff e:\.-posures elsewhere in Puget ofilld, The explanation advan ed tentatively i tbat both or the two lower till are of Admiralty age a light re treat and rea.dvance of the A G-ENER.A.'.L CKARACT.ER • In the other ·posure of Admiralty till known about Puget Sound the char!lcter is very siruilar to that of the younger Va hon till. Foliation is shown in many expo ure , rounded pebbles are usually &bundant, the matrix i arenaceous and the color i u ually an unwealhered gray. Granites of various kinds are a common in it as in Va hon till. The.re are no e ential diagnostic differences in the character of the tills themselves, and traligraphic relations must usually be taken into account in identification. Willi • has described the Admiralty till as changing to a dense stratified clay in many places both horizooui.lly and ver tically. A similar relation was expo ed in the Denny Hill re- grade of eattle ub equent to Willis' tudy of the region. • Jsewhere in uget owid tl1e writer ba. failed to find thi rela- • Balley Willis, ''Drift Phenomena. ol Pttget Sounrl,'' Bul. Geol. Soc. Am., Vol. 9, 1897. 176 - Bulletin 'ttlo. 8 Washington Geologicnl u,rvey tiou the till bein distin •tl differentiated from the overlying sediments nn nuely contairunc,, water-laid d po its. '!"he ba e of the .Admjro.Jty till was found in digging the Bell trcet shuc way tunnel of th Denny Hill regrade. Dark gray quicksand wa npo1·ted to underlie it the thickne of the till being about ~O fe t. An expo. ure of tbe ha e of the till is al o afforded in the ca cliff at the outh end of Bolton peninsula, Hoods anal Po t-Adminuty cm tal movement has locally tilted the bed of the section o that the ba e of the till lies above ea level. The till i overlain by coar e, dark- tained decayed gravel and rests on a weathered and leached stratified clay containing numerou concrelionary masses but with no gravel or and in it. Tbe clay outcrop nTong the beach slope belo,v high tide for a quarter of a mile and po e e throu"'b out a dip of .i5°. It i thus remarkably thick for a glacial deposit. It may be interpreted more a.ti factorily a Tertiary or early Quatel'Ilary, than Admiralty in age. The Admiralty till i generally um en-thered, and i in marked contrast with the ov rlying gravels, which l;\re deeply stained almo t every,rhere. There are many case of direct contact o·f these unlike mate.riaJ . The cau e for this i probnbl the same as that for the imilar con trn t of W1 tained clay trata inter stratifi d with tained gravels; namely the impe.rviou nature of the mat rial and the con equent ab ence of percolating water. In ome eA'J>OSUre a till which is thought to be Adm:iralt iu age a:nd which ce1·tainly i not of Va hon age, i con i.derably decayed o much o that p bble may be carved with a knife blade like ha.l , though the were originally of igneou and met nmorphic ma lerial. Thi deca ed till ha been found in cliff along Port Wa hington arrow , in many expo ure beneath the Va hon terminal moraine a out Little R ock and el ewhere. It i probably of Admfralty age, but becau e of po ition near the surface during the interglacial epoch wa weathered, while the more deeply buried till of the ame g1aciation was un affected. A till occur in R ed Bluff', near Ayer P oint, ood Canal, WASUl:-'OTl'I!< GF.OLOGICAT, SOR"\'El'. 131"'1, T,ETI N 1\0. 8 PLATIJ 3-'TV Denny Hill Regrade, Seattlt,. Gl,oaiation of the Pii,get oumd Region 177 in which decay has been more pro1ound than is shown else where in Puget ound. The extent of this decay exceed that hown b the Ted gravels of the Chehali Valley. Excepting the p bblc of quartz a knife ut through pebble and matrix alike without difficulty. The larg t fragment 8 inches in diameter, htrve no trace of a firmer ce.ntral plll't. Decayed gl'llnite pebble retain the appearance of the parent rock but cru h lo and and clay between the fingers. The reddish color of the whole i deeper than i u ual for the drift of Puget Sound, and gi,,es the bluff it name. Above and on both ides of thj e>.."}lO ure of old drift the bluff i covered with vegeta tion. The tratigrapmc relation of the decayed drift are there fore unk-'Tiown. It may be very pos ibly the deposit of a glacia tion preceding the .Admiralty epoch. With but two expo ures of the ba e of the Admiralty till, no estimate of its thickne can b made. It is wholly a matter of inference to tyle it a till shcPt.. Whether this till overlies older glacial drift or Pleistocene sediment!), or re ts on Tertiary rock i unknown. Ther are no data regarding tbe character of the topography ovenidden by the Admiralty ice and almo t none regarding the topography of its deposit . o glacial d-l'jft in the Puget ound basin i ln1own to lie south of the Va hon terminal moraine and its attendant out wa h, and in many place tbi moraine lie directly on previ ou ly unglaciat d rock. Con ide.ring OUl' pre ent meager knowl edge of the Admiralty glaciation, it is perhap idle to inquire into the cau es which allowed the Va hon ice to exceed the limit reached during the dmiralt epoch. A local cau e may be found to obtain. It may be uggested that if the Puget Sound ba in lay .higher, relative to the trnit of Juan de Fuca during the Admiralty than during tbe Va hon epoch, a greater propor tion of the Cordilleran ice would hare pas ed we tward to the Pacific during the Admiralty epoch than in the succeeding epoch. 178 Bulletin No. 8, Wa hvt1,gtorn Geological Suruey THE ADMIRALTY SEDIMENTS. GENEJUL DESCMPTtoN. The stratified bed between the Va hon and Admiralty tills are approximately horizontal in po ition wherever exposed in the hundred of sea liff s of Puget Sound. The e beds are truncated abrupUy by t11e bluffs, and by tbe lower surface of the Va. hon till where that overlie lopes in which a. sea cliff ha been developed. The e 1·elation are hown in the aocorn panying diagrammatic sketch. (Fig. !el.) Fully nine--tenth of the glacial drift ~'Cpo ed in the sea cliffs is composed of the e ioter- t-ili sediment . From the few expo ures of the Admiralty till above ea le el, the average altitude of it upper surface rnay be inferred to be somewhat below that plane, and the total thickness of he stratified bed must be correspondingly greater. The mate.i·iaJ of tl1e depo it range from clay to fine gravel. Coarse gravel with pebbles fist-size or larger is known only along the border of the Olympic Mountains on the lowland. In some places the material i clay for a considerable area. and depth. The busines portion of Seattle and the residence dis trict on First, Capitol, Mndrona, Renton and Beacon hills are underlain by a finely laminated clay which, in the Jack on Street and Dearborn Street regrade has been excavated to a depth of at lea t 75 feet without exposing its base. Other areas how a predomjnllllce of sand in the sections. This is notably the ca e in the sea cliff of Camano and Gedney {Hat) i land , and ome of those of Wbidby and Marrow: tone islands. A a rule, there are numerous (llternation of material, both vertically and horizontally. Willi bas attempted to cla ify these deposit for the Tacoma quadrangle, di tinguishing the Puy allup ands, the Orting gravels, etc. Tl1e method can hardly be applied to the entire basin of Puget Sound since the char acter of any one deposit seldom per fat fo1· more than one or two miles. Usually the gravels are bedded horizontally, but they possess stream cro s-bedding in almost every ection. They rarely form extensive or thick deposits, as do the finer mater1als. Glaciation of the Puget ownd Region, 179 STA.ININO AND DECAY OF THE ADMIB.ALTY SEDTh!E:?P' • The gravel and and of this series are ahnost everywhere tained by iron orid, in ome places to a. color as deep a that of the r d gravels of the Chehali Valley. The and i commonly buff colored, the gravel a e.llow or orange hue. Rarel , uffi cie.nt iron ox.id i · pre nt to i.nduxate tne gravel o that w ve ero ion cuJptw-e mall tacks and cave in it. The ta.in is uttiformly di tributed in the thickest beds seen. The clay beds of the erie a.re no stained. though gravel be.lo, lay ma.y be notably stained. Though decay has not greatly affected the e sediments, none of the gravel i a fre h and firm a that of Vashon age. U ually a test with a knife blade will ho r. a con id ra.ble difference in average bi:u·dness. Admiralty gravel is not u ed commercially because of it oftnes , while the Va hon gravel depo it are opened everywhere for building and road material Vl!:GETAL REMA.IN • Depo its of peat or lignite are interbedded with these st.J:ati Jied material in many place . The lignit i u ually compo ed of wamp depo it , the bulk of it being finely macerated mate rial with seed I cones, twjgs etc., scattered through it. Rarely tree and brushwood stump are found iin, situ a.t th bottom of such bed . The deposit in some ca are of water-worn d.J·ift wood · in t.ber bed , the presence of in ect wing , thin-bladed grasses, etc., shows accumulation in tagnant water. A bed of this lignite with a maximum thickne s of 10 feet wa di • covered in the Denny Hill regrade its area covering several blocks. Mo t of it wa of finely comrninuted org11.Dic material, in some places with con idera.ble clay, but large tree trunks, crushed flat by the pre ure of overlying bed were expo ed in the excavation. This depo~it and one on the outh side of Ander on I land have yielded charred logs and stick and many fragments of c11arcoal soatteired throughout the com.minuted material. A lignite bed on the east bluff of Admiralty Inlet f.1.t De Moine is composed ®tirel. of drift wood in one portion and 180 Bulletiin No. 8 H ashington Geological Survey pebbles of pumice ar plentifull di persed among the drift wood fragments, the pumice being likewi e tream-drift mate rial Such material could not have come from the glacial drift, and it reoord the pre ence of a. Ca cade river on this central pot tion of the plain during the depo ition of the Admiralty sed iments. In two instance , at least the lignite beds of the Admiralty ediment ha e been mi taken for Tertiary coal strata and prospect tunnel ha e been driven in them. One of these is at the head of Hood Canal near nion it . The other i in the valley of Feeny reek, olvo (We t) Pa ag . In the latter case, two horizontal tunnels were driven for a number of feet with the hope that the material , ould get ' harder" farther back from the outcrop. The lignite in thi pl ce occurs in two bed , three and five feet thick re pectively, eparated by 10 feet of clay. The upper Jigoite bed is more re istaut than the clay, and has given ri e to a pretty little wat rfaU in the creek. Lignite ha been found from ba e to summit of the tratitied drift between the Admiralty and Va hon till sheets, outcropping below Low tide in several place along .Admiralty Inlet. Any e~-planation of the origin of the tratified beds between the Ad miralty and Vashon till mu t take account of this vertical dis tribution of the lignite. ANlllAL REMAINS, The dmiralty ecliment have yielded mammoth teeth and tusk throughout mo t of the Puget ound region. o ma to don teeth have been foUJ,1d. A fragment of a tu k 6ve feet long and eight inches in diameter at the butt wa. found in gravel below the Ve hon till in a bluff along Hood Canal. l\iammoth teeth were found in the Denny Hill Tenth Avenue and eneca treet regrade m attle. Many ea1 lier find are on record. Two occurrence of marine hell in the cla of the dmiralty erie are known. A tony clay out rops a few fe.et above tide at the bu e of FouJweather Bluff. l\larine hells are a.brmdant in it fragile peoimens occurring with valve till attached. The Admiralty till lies direct1y beneath. Dr. Wm. H. D all has Glaciation of the Pug t ownd R gi,on. 181 kindly examined pecimen collected Crom thi bed nnd ha identified the follo\\·i11g pecie : (I) Mac<>n&a balthica in. (2) fl!a coma calca,rca Gm lin. (3) M nC0'/11,a (probably young middc'Tldorffii, Dall), (4) Ca,rdiwrn islandicumt F br. (5) crrip I gronlandicu, Beck. (6) Mua. tru1tcata Lin. oung. (7) ucula sp. (like bt•lloti Ad .). (8) axicti a arctica, ( 9) Leda f 0111,a, Baird. (10) Bel-0, p. ind. Dr. Dall tate that aU .pecie found ore living at pr ent in the colcler water of Puget oun • an thence northward to the retie. o clay pit at outh ee.ttJe cnvated in the ba e of the we tern lope of B a on Hill. have al o r vealed marine r~ main • The cla i like tl1at o frequently exposed beneath the busine s portion of the city of attle in the Ja k on, Dearborn and T th Ave. regrade ·, and el ew·bere. Iuch the ame mollu can !11.una wa found a in the Foulweather Bluff' section a.nd in addition ru tacean clnw were di cover d. In the outhern pit owned and operated hy {r. iederge aes elk untler and 11 whale ( ?) vertebra hnv heen found a r feet above the horjzon at which the mollu can remains occur. Mr . .Terb rt the foreman of the pit who witne ed the di covcry of lhe antler j careruJ to di tingui h Lidden materiaJ from la in situ, and bj laternent may be taken without h sitn- lion. areiu] w tch wn kept for verlebnlte remain dltring the destru •tion of the D n11y Hill lignite bed, but none w re found. The occurrence of rnnrine hell in Foulweather Blulf clo e to the bn e of the dmiralty ediment. , o..lTord a pr bl •m ·hich will be olved only b. t.he dj cov-er. o( more marine remain in the e emment . The problem i wh thel· the ea entered by way of the trait of Juan de Fuca or extended back from an 18.2 Bulletin No. 8, Washington Geological urvey e tuary in the Chehalis Valley. If the e ecfunen are largely outwa h from the dmil·alty Glacier it eems impos ible tb1,1t the ea. could have enter d from the trait at the north at the time of their depo ition. The occurrence of marine remain only at the ba e or close to the ba e of the stratified drif erie , o far as observation ha gone, is a ignifica.nt fact which mu t enter into any expla nation of the genesis of the secliments. INTERCALATED TILL. Till bed intercalated u~ith the edimentary strata baV-e been found in a few places. The ea tern bluff of Admiralty Inlet two mile outh of De Moine the south ide of Danas Passage and T utsko Point on Toa.ndos Peninsula, exhibit such relation. The section of Pos e ion Head de cribed in a p1·eceding' para- graph, i thought to belong in this category. Deposition of till in thi position must have been contemporaneous with ac cumulation of the edimentary series and i explained as the pro duct of an oscillatory re-advance of the ice dming the Admiralty retreat. THE MC NElL lSLANU SECTION. A few in lance of con iderable deformation of the e Admir. alty ediments are known. The mo t. pronounc d ca e i the bluff of McNeils Island a.long the water front of the United tates P enitentiary. The deformation here take the form of folding, in places so pronounced that the anticlinal fie. ure ar harply apexed and omewhat overturned. ( ee Plate II Fig, 1.) The matel'ial affected i unconsolidated and and gravel and the folds are probably not more than ten feet a.eras . That thi cli turbance wa not produced by the over riding of the Va hon ice is shown by the exi tence of horizontal bed of the Admiralty erie above the folded t.rata the fresh Vushoo till overlying both. Sliding or slumping cannot have caused the deformation, ince it i persi tent in greater or less degree for a mile along shore, and is in coar e material \ hich does not ordinarily lide. There are al o no fault ucb a liding would produce. Glaciatio·n of the Puget Sownd Region 183 Two other e..xplanations remain; ice thrust during deposition of the series, and CJ·usta1 movement subsequent t-0 deposition. There is apparently a till layer in the upper part of the bluff at the Penitentiary dock, with stained grave1s above it. In accessibility of the summit of the bluff prevented positive iden tification, but the presence of contemporaneous till is practi cally required, if ice thrust produced tl1e defonnation. Crustal movement seems totally inadequate to produce the sha1 p crumpling of the g1·avel beneath nearly horizontal strata of the same age. The surrounding region has not suffered severe d.iastrophlsm since the T ertiary. The disturbed gl·a.v els of McNeils I sland are therefore interpreted as due prob ably to ice thrust immediately subsequent to theii- deposition. SECTIONS OF USELESS BAY, ETC, An unusual distorted structw·e of stratified sand and clay is shown in the bluffs (1) on the north side of Useless Bay on Wbidbey Island, (2) near .Algiers Bay on Camano Island, and (S) along Hoods Canal a. few miles south of Fouhveather Bluff. The sea.cliff of Useless Day referred to, a mile east of Double Bluff, is nearly SOO feet high. It is composed almost entirely of stratified clay, sand and gravel, a. few feet of Vashon till appearing in places at the top of the section. Lignite is pres ent in strata not exceeding two a..nd a half feet in thickness. The thickest lignite stratum is of considerable length, and is uniform in thicl"Des-s, indicating formation on a Bat plain in stead of in a channel or kettle hole depression. There is no evidence of the proximity of ice during deposition of the series, and no till is ex.posed at the base of the section. A zone about twenty feet wide is exposed in the lower part of the entire bluff, composed of clean gray sand mingled with yellow clay in a most striking fashion. The clay occurs in fantastically irregular masses, ten feet or so in diameter, and distributed horizontally SO to 50 feet apart. These masses are usually elongated vertically, and possess very irregular arms projecting vertically and horizontally into the sand. 184 Bulletmi No. 8, Washiington Geologfoal Swrvey urrent-bcdded and lies below and horizontall b dded and and clay lie abov he deformed tt'ata. rl'be scacliff on the ea t ide of Hood anal t)Hce miles outh of Foulwea.ther Bluff pre ent a imilar tructm·e. In the e ection the yellow clay ma e bear a rude i-e emblance to 11 heu.f of ribbon , bound at tbe top, and crumpled and pread at the bottom under it own weight. Smaller rna e of the clay re emble prre thru t ertically up into the overt ing ma . Horizontally tratifi d clay lie below the e di torted beds, and pra tically horizontally tr tified clean gra sand lie among the ' heave . J Distorted clay trata of the ame nature are expo ed in ea. cliff of amano Island. a little south oi Algier Bay. The distorted stratum i about two fe t thick, and in mo t place is so completely bent and crumpled a to have lost re mblance to a tratum and to po es the ragged appearan e of the clay ma e in the . ea cliff north of ele s Bay. ome of the e clot-Uke ma e are 1 completely defo1·med and the stratum of yellow clay can be traced from either ide into them and to the ummit a bown on Plate VII the appelll'a.nce then being mo1·e like th heaf form of the Hood Canal occurrence . Very little trace of bedding can be een in the sand which lie betw n the crump} d ma. of clay. The trata of and immediatel overlying the distorted zone are un disturbed. ,-' In the production of the di tortion, the clay tratum either I ha been hortened by lateral oompres ion thu lo ing a large fraction of i original length or ha been. queezed thinner by vertical compr ion which ha forced the cla to ri e in the e fanta tic ' dots" or "sheave ,, o di po e or the di placed material. There i n0 evidence in any of the e ection that the sedi ments abo e or below t.he deformed zone ha e been affected. In two a es a light unconformity e ri t above the deformed zone in one of which the tip of an upthru ma i truncated i z c ...:; Glaciation, of the Ptt,gct Sownd Region 185 (Plate X II). Thi indicates depo ition of the o erl ing bed after di tortion of the clay. The deformation f these bed certainly occurr d dru·ing the depo ition of the and immedi tely o erlying the deformed cla.y ·trata. ru tal mo\'cment or action of glac.i r ice can hard.1 have been the cau e eii:ber of whlch would have affected the beds 6 bove and b low and the latter of whi h ould ha e left it 01vn di tinctive depo it uperpo ed. nly vertical com pre siou could prndnc th deformation and lea e the under lyfog trata uneff ected. It i a. ianif:i ant fact that quick and are. expo ed at low tide at the foot of the prevailing sand bluff of ronano and Wh.idbey I land . ucb beach material i deriv d without doubt from the erosion of these sea lift' of fine and. Quick- ancL arc not .ln1own to the writer to occur el ewhere on the hore of Puget ound. A omuination of pla ti day beneath quick and e pecially when th material contains rnucb i11ter titial wat · because of t11e r cency of d position and the lo.ck of complete eltling, might po se a rn bilily which c uld allow th deformative change known in the Hood anal Whidbe land and Ca mano I la.nd ections. The force producing the deformation mu t have b en dir ct) rnvit ti e. The change produced a greater compa tne of th material by n---pu] ion of inter- +.itia.1 water, o that ub equent depo it of qui k and were not affected. The uggested gene · of the e di torted m11. ses is ome, hat imilar to that advanced by HilO'ard for the Mi - si ippi Delta mudlump •i and the cro ection. here de-- rribed po s i11 ome place omething f the 'onion·• huc bue of the mud.lump . DELT. I. TH..E ADMmALTY $:eDlM.ENT • In the identification of cle)tn b dding in tl1e Admirnlty edi ment distinction i to be made between the long fore trnta. of 11, deltn ma s, and tlie horter and common! iuterrupted • E. W. BIJgard, Science, Dec. 28, 1906. 186 Bulletm. No. 8 Washington Geological Survey foreset beds of small d ta-Jike deposit built in channel depres :ion . The latter are ommon in the horizontally stra.tiJied gravel of the Admiralty erie , while only four o currences of for set delta bed o.f Admiralty age are known. (1). A eacliff on Dabop Bay about a mile north of Palali Point, expose horizontall bedd d dadtl taincd coar e gra el lying laterally and unconformably again t and over finer gravel of the sa.me character but with a dip of 9W 0 . E. outh of thi gravel with northward dip are other old gravels of the same chw:acter, but w-ith the tumultuous bedding produced by swift treams. Pebble of granite, though rnre, ex:i t in each of tbe three portion of the bluff. The whole is of dmiralty ag . The bedding with !'l0° dip doubtless originated a the delta depo it of an 01 mpic river in a lake formed durina the Admiralty retreat. Later the lake wa drained, the delta partially eroded and the rea then aggraded with the horizontal] .., and urren·t-bedded et>atse gra~rel . The granite pre nt wa probably earlier carried up into the lympics by Admiralty ice at it maximum ju t a wa · done during the Vashon glaciation. (2) . The peninsuJa tipped by Quat ap Point forms an ex.- eptional projection into Hood anal. I northern ho:re iB composed of basalt, and its sou hern bluff p-re ents a plendid ection of anotlJer delta of Admiralty age. The sea.cliff for a length 1of half a mile is compo ed of brown-stained stratified gravel with a notth at dip of about 20°. (See Plate XII, Fig. 9l.) Va hon till overlies its eroded upper . urface. The gravel contain no pebble, of granite or o her holocr tnlline t,ock. t the we t end of the ection the d ]ta bedding has e n truncated by ero ion and a Inter depo it of buff-stained horizontally bedded and ov ·lap the gravel. Doth are of dmil'alt, ag and overlain by the Va hon till. Th tratified gravel of Quo.tsap Point cannot be interpreted a tilted trata for two reason . ( ) The thick'"Il , if the trata were horizontal would far exce d that of any known Admiralty ediment and would po se s the unique feo.ture, Glaciation of the Puget Sownd Region 187 among the e seilimcnt of being of one character throughout. (b) There is n obliqu truncation of ome of the fore et beds by overlying one whi h are di po ed nt a lightly flatter angle, aB in £i.gure i~. This could not be formed in strata. deposited horizontally whi1e it i a nol'mal delta tructuxe caused by (I. slight shifting of the direction of current, just at the de boucLure, on the cdo-e of the deltn top. The Qua ap Point Delta wa built of Olympic o-ravel by the Duckabu 11 River at the time of Admiralty retreat and in a lake ponded in front of the Admfra.lty Glacier. Like t:he stream which depo ited the Pulali Point Delta the direction of the flow w'luch con tructed the portion now existing wa northward though in each ca e thi portion may be imply the nol'th m parl of o.n ori inaJJy emi-circula.r delta. The base of the Quatsap Point Delta i below e11-level, and it ummit plan bn been. eroded, o that the d ptb and alti tude of the surface of the former lake can not be kno\Vn. That the two deltu belong to one lake i probnl,le. Tbe e.ti ting remnant of ea h delta has been protected by an outcrop of rock directly north guarding it from ero 10n by the Pug t ound Glacier of the Va hon poch. (S). orth of Point Lowell, on the we t ide of amano Island, fore et-bedded gravel appeur .in the ection o erla.in b Va hon till. It i irregularly tained, but apparently be lonO', t the Admiralty ediment . The dip i north.ward and the truckne e.,-po ed i about 25 feet. A lake whi h teceived drainage from the outh during Admiralty retreat i. thu rec rded. Like the Admiralty lake of the Quatsap Point and Pulali Po.int delta , it was probably ice-dammed. (4). Willi ha de cribed and figured delta-b dded g1·avels of the Admiralty series in the bl11ffs above the 1orthern "Pacific dock at Tacoma•. They are not a well develop d as are the fore et beds de c1·ibed above. They are to be referred probably to ome 'a cade Rivci· which i ted during the retreat of the Adrrurtllty ice. Willis wn not fully 11iti tied that they and • Willis, Bailey, Bul. Geol. Soc. Am., Vol. 9, 1897. 88 Bulletin No. 8, TV ashi1igt()'TI, Geologiaal urvey the Tacoma (Va hon) Delta were dis inctly di.fferent deposit . ince they are separated by the Va hon till there :i little doubt that they are ery different in age. GENESIS OF THE ADMIJI.ALTY SEDibffi T , The tratified mat rial between tbe Admiralty and Va hon till sheet wa depo ited during the later tage of glaciation of the basin by the Admiralty ice- beet. This conclusion · supporled by the following evidence. {l) Rock material f reign to the neighboring mountains are present in the trata. Thi is especially notable along the Olympic margin of the ba in, where pl ndid expo ure by the sen cliffs of Rood Canal how no dominance, and indeed no con- iderable proportion, of Olympic wa te in the material. (~) Till i interbedded with the tra.tified depo. it . (S) The trata in ome pla e al'e deformed apparently b tl,e thru t of glacier ice. ( 4) There i an ab,ence of tructure and of gradation in material which 1rould indicate derivation of the detritu from the flanking mountain . Two onception may be advanced for he origin of the Ad miralty ediments both ba ed on e ame ptemi e ; that they a1·e compo ed largely of glaciall trnn. ported material, an.d ha e been derived onJy to a maJ.I extent from the drainage ba in of the ound. I. It may e conceive first that tongues 0£ Admiralty ic lay where the trough or inlet of Puget ound now are and that t11e inter p ace became aggraded by water-borne debri from melting of the ice, and by dcpo its from the ice directl . Final melting would then leave the pr ent hills or ridges s p arating the d pre ion , hich were pr erved by the ice durin the agc:,,radation. By uch method of origin certain struc ture ,Yottld be formed in the depo i the presen e or ab ence of which in the ea cliff of Pug t ound bould rea onabl te t this hypotbe j . II. The dmiralty ed iment a] o may be conceived a hav ing been continuou originally over the whole of the drift-cov- Glaciation of the Puget Sound Region 1 9 ered lowland of Puget ound, the trough o.nd 1·idge being the result of subsequent ero ion of thi plain. The melting ice ltl.l'gely responsible for the .a.ggradation, lay to the north and as its margin retreated the tream and standing water de po it buried its till. The plain, during aggradatfon, was trave.r ed by river ,vhicb were continually filling theil' chan nels and shifting their coUI'ses over the stretches of low, flat land between them. Tract of quiet, hallow water probably stood over considerable area at different times. By th.is method of origin of the Admiralty edirnents certain structures also would be formed who e pre en e or ab euce in the sea cliff and other e tion will be the te t of thi hypothe is. Th difficulty met at once in con ideration of be fir t hypoth.. es.is is tl1e la k of a ati fa tor e.."q)hmat.ion in harmony wi h the fa ts !01· t]1e occurrence of glaci1u tongue on the Puget Sound lowland oriented in g ueral north and ou~ and sepa rated by interval of low but i e-free )and. Willi who ha previou ly u.d,•anccd thi hypothe ·i , concei e thick lake clays could never overlje horizontally tratified gravels unless the Jake level rose after the ice-bound depression had once been filled. (2) wamp depo its of peat £md lignite likewi e a.l'e po i- ble in uch a erie only alter the lake ha been hallowed by filling with ediment, or by lowering of outlet. Lake clay above peat or lignite might ·ceptionally be produced by a ri e in lake le el (3 Marin depo it in the lower bed of such a ecie would be very improbable. (4) Ice thru t from the adjacent glacial tongu might be of common occurrence. Tm would give ri e to crumpled sediment and layer of intercalated till. (6) in e most of the erie would accWDulate under tand- ing water ero ion uncomformities between strata ( caused by hilting trea.ro channel , ould be very improbable in the lo er bed . (6) There would be no pos ibility of correlation of strata in any two such Jake deposit . If the Admiralty ediment were depo ited by heavily laden stream wmch hifted to and fro o er an aggrading plain a the econd hypothesi hold the following character hould be formed in the tratified series : (1) Deposit from wift tream sluggi h tream and standing water would be superpo ed above each other in all parts of the region without regard to what lrind of ediments lay beneath. Thus there would be no vertical equence of sedi ment , and horjzont.8.lly ht1-tified gravel would belong a much among the ba al bed as among the uppermo t. (2) Since wamp might form at all stages of tl1e aggrada tion lignite and peat might occur from ba e to u:mmit of the se:ries. (S) Marine organisms would be most likely to oc ur at the ba e of the eries, before aggradation rai ed the level of the plain above the ea. Shell of marine mollusc would not occur in the upper bed unless the region ank during aggradation. Glaciation of the Puget Sound Region 191 (4) The immeclie.te presence of glacier ice i not required by this conception nnd crumpling of the ediments by its move ment should be rnre. orre ponding1y Jen e Ol' enm of till, interbedded with the tratified materials hould be uncommo1', and associated chiefl with the lower bed-. (5) The lateral shif ing of rlream over a plain which i being aggraded would erode the surface of ed already de po ited and ould produce unconfo:r-mit in the b dding. This phenomenon should be common f.rom bo. e t-o uinmit of the series. ( 6) Correfo.tion of trata aero the. present troughs migbt be po ib]e in ome p]nce though the repeated horizontal change in character of the ecliment would render correlation difficult, if not impo sible, in most ca es. To bring the whole problem into conci e form . a summary of the feature hown. in the ea cliff i h rew-ith presented, and their bearing on the two hyp the e i indicated. (1) 1 orizontally bedded gravel and clays are inter- trati fied without re.fe~·ence to U1e vertica.1 sequ nee demanded by the fir t hypothe i but in entire conformity with the econd. Delta bedded aravel are rare in tbe g1·eat ma s of ediment and wJ1er pre ent do not dip from the troughs toward the ridges. (!e) Lignite bed range from the lowest to the- hlghest por tion of the edimentary e1·ie . Thi i very improbable under the 6r t bypothesi , but in perfe.ct accord with the econd. (8) Remains o:f marine orgnni m have been found only in the lowest bed abo e tide, thi evidence f avo:ring the econd hypothesis. (4) Crumpling of the e.diments by ice-thru t during depo- ition of the eries j rare, and is practically confined to asal b d . H hould be fairly common throughout the whole vertical range according to the fu t hypothesi . terbedded till i rare. B the fir t hypothe i it should be a fahl common f e1;1.ture in the ection in the periphery of the ridge and hills. (5) nconfoTmities of a few feet :in ,•eTtical range, ca.used by tream ero ion, exist fwm sea level to the highest sections 19l Bulletin No. 8 Washington Geological Swvey throughout the entire erjcs being e pecially common in the gravels. Thi is practically impo ible by tbe firt method of origin. (6) Fairly probable conelation of depo its aero trough have been made mdicatina the:ir former extent completely aero , and 01·igin of the troug11 by ub cquent ero ion. UD.lltlary of thjs "amination find . lh fir t hypotbe i - t hat of aggradation of the rido,es etwe.en tongue of i e hopele Iy di puted on everal point , and without definit :up port from any. Tbe umulntive value of the evidence cited houJd e tabli h conclu jvel that th hills and ridge of Puget ound a1·e remnant· of a once continuou plain of tratified drift. The hypothe i of accl' tion, or glacj l con tru ·tion of the Puget Sound ridge anid hills may be applicable in ome cases for the Va hon glacial depo it when tongue of Vashon ice lay in the alley of interglu ial ero ion and outwash accumu lated on hilltops but it fails for the earlier d po its which com po e by far the greater bulk of the drift of Puget oun . The Puget ound basin then i to be on idered a having been floored from rim to rim with a great plain of mmgled muine lacu trine fluvial and g lacial depo it b the clo e of the Ad miralty epoch. ub eq ucnt ero ion ha produced the troughs in this plain. ummit l vels of the major drift hill and ridges of Pu..,, t Sound accord triking!_ in the profile of a plane extendin"' from the Olympics to he n ca.de . Wl1 re the a cad diagonal tnoUJ1tain pur inter ec the bn in fine view are o.:fforded of contra ted d1·ift JJj]] and rock biTI profile • ong and n arly horizontal lines mark the runmit of the dt·ift hill o.bov which the rock hiJl ri e from a. few hundre I to a f w hou and of feet. Thi ontra t is a trongly mark d on the south or lee side of the mountain pur as el wher , a feature to be expected in a plain aggrnd d 1 rgely by runrun .... water. In a study of the lympic margin of the Puget ound ch-jft plau.1 alluvial fi,..n and delta stn,1ctu re urrent b dd.ing with P1srP. \'I FI . 1. Porlion of Denny Hill R gra I , a1rle. F1 . 2. Tile Gl'ade of Bell tr t, D nny Hill R grade. at I • Glaciatum of the P11,get ou,nd Regi The great thickne of the Admiralty ediments in the Puget ound basin contra t trilcingly with the light amount of pre Va hon Pleistocene nggradation in the portion of the struc tural valley to the nol'th and outh. This difference clearly indicate favorable local conditions and the one dominant con dition appear to have been the lingering of ordilleran ice in the ba in. SUM iAltT OF T.EtE CHAPTER. (1) trati6ed ediments between the Admiralty and Va hon tills compose at least nine-tenths of the Plei tocene deposit of Puget ound above ea level. (2) The e sediments were deposited probably larO'ely by water flowing from the melting Admiralty Puget ound Glacier. ( 3) The level of the ea during ilieir depo ition was dose to pre ent ea level lignite being found today from below tid to the ummjt of the erie 400 f et above tide and marine fo il occurring only in the lower beds close to the pre ent sea level. (4) The tratified depo its were laid down a a wide plain in the geo yncline of Puget ound. (6) The ba al portion of these Admiralt sediments is ma rine in part. The greater part of tbe eries i terrestrial. CHAPTER vm. ORIGIN OF THE TROUGHS OF PUGET S0U~1D. SYNOPSIS. GENEllAL DESCRIPTION. ~ OntGIN OF THE TnouG:as. TnE lNTERGLAOIAL DRAI.NAGE SYS'rEM Sounr OF THE STRAIT OF J uAN DE Fuca. ITEMS CONTROLLING RECONSTRUCTION OF TKE DlLAINAGE SYSTEM. PLIOCENE ELEVATIONS A:noVE TTIE AnMmALTY PLAIN. SLOPE OF 'l'H.E ADMmALTY PLAIN. PosT-AD1\11RALTY DuonMATIOJS. Onr.eNTATJON OF T.nousHs OF PuGET So.nm. RELATIONS OF VASHON TILL TO Tll:E TROUGHS. RECONSTRUCTION OF THE DRAINAGE PATTER~. THE GATE PATHWAY RIVER. TnE :.M ;ATLOCK PATHWAY Rn·En. THE Ao~trRALTY RlvEn. Su:n-i\>fATmirrY OF THE INTERGLACIAL E1t0SI0N. THE L'ITERGLACIAL DRAINAGE NORTH OF TKE STJUl'l' OF JUAN DE FuCA. TKE "DEEPS" OF PUGET SOUND, lU.INoR RIDGING OF VAsa:oN OnIGIN. GENERAL DESCRIPTION. The most noto.ble feature of the topography of the Puget Sound basin, south of the Cascade Mountain spur, is the meridional parallelism of major forms. The observer with au eye to the origin of this persistent feature is at once impressed with the fact that these meridional valleys and divides, at least above low tide, have been fashioned almost entirely in glacial drift ~d strati:fied Pleistocene sediments. The only part of the basin south of the mountain spur where 196 Bulle-tin No. 8, Washinigt()'fl, Geological Survey tl1e trougbed and ridged topography fails, is south of Tacoma and Olympia, in the region of greatest deposition during the Vashon epoch. The greatest trough of Puget Sound occupies the meridional axis of the synclinal valley, and contains Admiralty Inlet. The length of this inlet is 60 miles and its 1.1.verage width is S to 4 miles. It maintains a depth between 575 and 900 feet below sea level for a distance of 45 miles. The avenige height of the bounding bluffs is about !00 feet. The deepest place in the trough is probably off West Point, Seattle, where the water is 800 feet deep, and the bluffs on both sides ai-e 300 feet high. Like the other smaller but still considerable troughs of Puget Sound, this great valley is a Pleistocene p1·oduct. The lai·gest trough west of it is Hoods Canal, and the La1·gest on the east is the Marysville-Snohomish-Snoqualmie Valley. The vigorous rivers from the Cascade Mountains have filled the eastern troughs with allu'1ium, so that the Sound today -floods only the middle and western part of the trough system. THEl ORIGIN OF THE TROUGHS.• Three different modes of origin have been suggested for the Puget Sound trough valleys ; stream erosion, glacial e.l'Osion and glacia.l accretion. Considered from a map alone, the origin of Puget Sound appea1·s a simple problem. Many have referred to it as a drowned river system of preglacial development, confusing it with the 1;ver- and glacier-carved fiord coast northward to Alaska. Upham uses it to prove bis high continental eleva tion which brought on the ice age, and when visiting the region, _persistently mistook the stratified Admiralty clays for T e1·tiary shales. Kimball has argued for the postglacial erosion of these valleys. Newberry probably was the first to bespeak an origin by glacial erosion for these troughs. He thought the glaciers • Re!ereuces to the literature wlll be found in the introduction to this paper. Glaciation of the Puget Sound Region 197 moved northward toward the Strait of Juan de uca. ub sequent1y others have r r d the direction of glacial move ment, but have held to the idea that a piedmont ice ma s or broad glacial tongue developed the ple ·u of trough valley beneath it elf. The eductive featun of thj bypothesi of glacial erosion is the rnde -pa-ralleli m of the trough with the direction of glacial movement. Ru sell bas advanced, and Wjllis ho upported the accre~ tion or con truct;ion hypothe i for the origin of the Puget ound valley . This view i e entia11y he flt• t h po hesi advanced in our di cu ion of the origin of Admiralty ecliment . illis remove the d_jfficuJty of securing independent ice tongue on the lowllllld by as urning a pre-existing valley ystem cor r ponding to that of tl1e pre ent on the divide, of which the glacial and edimentary 'erie wa deposited. 'By repetition of this pro ·es , [ice occupancy of the troughs and deposition on the inlcr-area ] the antec dent divides were built out to plateau forms and the a.,."{es of !:he original valley were maintained a relatively hallow hollow which are thu the ca ts of glacial tongues."• In the above tn.tement illi definitely commits him ·ell to the hypothe i of glacial con truction. His tu.tement o.ppar ent1y includes .Admira.lty as well a Vashon glaciation. The great .improbability of uch origin ha been shown in the pre c ding chapter, and it may be added further that a tudy which ha included almost every ea cliff of the Puget ound country ha· failed uniformly to fwd any trace of underlying rock DJll es uppo ed to exist in the ridges and plateau of gh1.cia.l drift. Where rock does appear in a ea cliff it bear no relation to the hill of drift, and in many place interrupts or con trict the trough , a relation which would be impo ible if U1ey were pre glacial volley . In th volume on Glacier and Glacfotion of the Harriman Ala ka E1"Pedition report, G. K.. Gilbert ug c t that Admir alty Inlet may have been th lower course of the Columbia River • Bailey WllUs, Bui. Geol. Soc. Am., Vol. 9, 97 . 19 Bulletin rilo. 8, Washington Geological ·urvey which in pre-glacial time ma have flowed northward rn the tructunl valley, from Portland to the h-ait of Ju n de uca. Datt\ p1·e ented in pTeviou chapter of thi paper make it clear that ucb n bypotb is find nothing in the field to sup port it, and that there a.re in operable obj ction to it. The divide at Tapavine probably ha never b n crossed b a tream, ertainJy not since the deep decay of the Tertiary rock. The Gate Pathway interrnpted b) two rock hill too na :-row for the pa age of a b·eam like the ohunbia. T11e Pliocene vel or H I h Ticle Fm. 21. Rel11tlon of Vashon Till to .Ad.mlralty edlmeDts. OiugrlllD &bowR crucc11tion of strnWl a .Adllllr1Llty seillmt'nt& by 11 s IL Qlllf I faeillg observer and t,y IL pre- eshon roslon slope (OD the lllft bear ill g Vll8llo.n Ul.1. heha.li Valley i wide open from Gat to the ocean and the olumbia would have taken that cour e, had it ever cro ed the divide at aptwme. And, .finall. , U1 troughs of Pug t ound eroded in Plei tocene deposit , are interglacial not pre gJacial, in a.ge. It is belie,·ed that any attempt to explain the oi:igin of the topography of uget ound by on p1·oce i doomed to fail ur I that the trough have ha.cl a polygeneti origin and tbat study of uch trough i nece ar to olve the prouJem of it gene i T Latei· in thi chapter, the variou trough will b con idered indivjduall and thi on ption developed in more detail. evera1 of the htpothe es ad anced arlier have tooched upon the truth. Preglacio.l nncl interglacial tr m ero ion have function d glacial ero ion ha operated apparent] in cer- Gfocirition of tltt Puget Sownd Region 199 ta.in ituo.tion o.nd glacial depo ition ha incl'ea ed th he.in>ht of ome hill relative to the adjacent trough during the Va hon glaciation. Of the e severu.l p1•oce e that of interglacin.l stream ero ion has been by far the most important. The evidence. for the pr domjnance of thi proce ma be summarized n follows : Mo t of the troucrh how the char acter and r 1ation of t.ream valley , and they post-df\te the deposition of the Admiralty ediment and ant date the Va hon glaciation. Data. have already been pre ented ( b. VII) which bear on the abo e points and more will be advanced in the following paragraph . THE INTERGLACIAL DRAINAGE SYSTE J SO TE OF THE STRAIT OF JUAN DE FUCA. After the Admiralty glaciation, uplift of the region of Puget Sound eccurred accompanied by locnl deformation of the gla cial depo it . Thi po t- dmiralty uplift wr-1. p1 obnbly about 1,000 feet gretder than that which ha follow cl the Va hon glil.ciation and proc'luced pr eat altitudes. A long pau e in ru ta1 mov -ment followed while l'eam e:ro ion cut deep val ley in the urfac of the plain. ince the mat rial wa un con olidated and the tream gro.di nt were hi.,.h, the work of eroding a drain&gc . 'tem wa brief compared to the dev elopment of uch on a rock t:er:rune. The stream vnlley which w e eroded at thi time in the Admiralty glacial depo ·t wer il'lll. k d but little in gen al by the Vu.shoo glaciation. Lo •ally, they were apparently deepened by ero ion of the , a hon Glacier. Valley I ing at right angle to the com: e of ice movement were ohscw·ed more tban tho e with oth r orientation. In the outbern part of the ba in, the troughed topography wa completely obliterated by the periplu~ral depo it of the I a hon Puget ound Glacier. lTElr ONTROLLING TKE RECON TRUCTION OF THE DRAINAGE :Y 0l'E~t. Any attempt at recon truction of the in el'glacial drninage sy tem mu t recognize the follol\·ing it ms: (1) The elevatio1 of the Pliocene topography which ro e iOO Bulletin No. 8 Wa.shington Geological Swrvey above the Admiralty drift plain and controlled the inception of the int rgla ial drainage pattern: (!e) The original lope of the Admiralty plain: (3) The pos ible d foi•mation of thi lope. (-41) The orientation of the mll.jor trough of Puget Sound. (6) The relation of the Va hon till to the intercrlacie.1 val- ley . (1) ELEVAT.IO' OF TH:E Pl.IOCEl'..-B TOPOGRAPHY AllOVE TIU AnMDbU, TY PLAIN. In the con jderation of thi item account need be taken of but two arens be id(> the hiJls and mountain .nta.ra-ining the tructura] ha in. Tlw Blue Hil14 ar itu ted entrally in the ba in. They ri e a few hundred feet ab~ve th ridg and plateuu of drift which sepa:rate the hough of Puget ound. Tb . hill. lie between the two ma ter trough now flooded ; Hoods anal on the west, and dmiralt InJet on the east. Thou h not suf ficiently elongated to er e a a mvide the area of the Blue HiJI mu t have be n the eff c ive factor in deterrnining th cons gueot drainage which pr du d the tw great trough . The Blac7. Hills con titute a larger and higher remna11t f th pr glacial topography. hey lie north of the hehali Ri er and pa.rate th Gate and Matlock Pathl a.y :which are al o pr olacial topographic feature . In the ab nc of deep boring n thing i kno, n of the depth of the dril in each broad gap. In thi lie the wea.ke t point in the recon struction of the interglacial dJ"ainage y tem of Puget ound a ,vill a.pp ar . bortly. It htt not been proved e that the red gravel of- the Ch holi Valley nre outwa h of dmitalty o. carried throu h the Gate and Matlock Pathway though the current b dding of the Admiralty gravels in the ou her mo t part of Puget ound po e es a per i tent outh, a.rd dip toward the Gate Pathway. {fl) LOPE Ol!' 'l'HE AD mU.LTY PLAIN. Since the Admir- alty plain wa aggraded probably b, water flowing toward the outh ( h. VII) the debri and water being upplied larg ]y by the Admiralty Glacier at the north the original lope must 0 E :, Glaciation of the Puget Sound Region !!01 have been southward. The comwon hallow foreset- or cuuent bedding of the Admfralty outwu h gravel nearly everywhere rup in conformity with tbi theoretical con ideration. Thi fact make it probable that th red gravel of the ltehali alley are correlative of the O"ravel of the Admiralty plain though granite, the characteri tic rock of Pug t ound drift, has not been identified in them. Though the region of Puget ound ha een elevated and depre ed rep atedly since the n.ggradation of this p~n, th sea.cliff sections reco1·d onl local and light deformation of the trata re ulting Crom the e movement . The ummits of the ridges and plateau of the former plain become gradually lower Jl'10 . .22. Oblique Truncation of tbe Foreset Beds of Qnatsap Polnt Delta. southward from the latitude of Seattle or Tacoma and thi de cent may record tbe original lope of the Admiralty plain. We have ee.u that during the retreat of the Va hon Glacier from the ound, di.version of glacial water from the hehali Valley at the outh to the trait of Junn de Fuca at the north occurred before the front of tl e ice had rec ded to the trait. It is entiiely probable that the history wa imilar during th retreat of the Admiralty Glacier. If so t.be Admiralty plain in the no1·tbe1•n part of the basin hould have had a northward nd we tward lop , nnd this lope 11ould be record d today in a northward and westi ard dip to the current-bedded edi meut and perhap al o in a gradual lowering of summit levels in the ame general direction. tO!!! Bulletin No. 8 Tf nshington Geological Su,rvcy The Tacoma attle and Mt. Vernon quadrangle together coyer a meridional di ta.nee of about 100 miles in the ba in of Puget ound a.nd mu t include the latitude at,; hich UH! dmir alt dro,joage abandoned the outhward our e and beg,tn to flow to the b:ait. Except near the mounts.in the ummits of the rid es and plateau of drift for the whole di tan e are ab ut 550 (eet in altitude and no vid nee of th former di ide i found in the pl'escnt topography. urrent bedding in fine and of Admiralty age ben ath a hon till i expo ed in the ea cliff on the ea t id of far row tone I land. The dip j almo t without .xception toward he north. and of much the ame character .aero drnirnlty Inlet on hidbey I land po e current bedding with dip in the ame direction. Though · dip doe not prevail in the dmi)·alt sediment of thi part of tbe ound, it is seldom disputed by outhward dip in the cro . -bedding, and the con clu ion appear ound that water flowed nortl1wa1·d r north we tward aero thi . portion of the drniral y plain dudng the time of Jt nggradation. The deduction from thi consideration of the slope of the Admiralty plain i that the interglacial drainage pattern wa probably controlled by a mid-ha in low divide which cros ed from the a cade to the Olympic outh of tbe latitude of Ever tt. The hehali River received the water from the outhem lope and from river debouching on it from the bordering momrtain while the trait of Juan de Fuca re cei,red the direct and conti·ibuted runoff of · he northern part. {S) Po -r-Amcm.ALTY D.ruro1tMATI0N. The strata of the Admjralty drift plain ha,•e been elevated twice ince thei1· depo- ition. a downw,n·d mo em nt intervening. ince however the plain i made of terre tial depo its with the stratification pro duced by on ta.ntly , arying condition of wift 1uggi h, and tandu,g water in different locnHties no stratigraphic method for dete tion of deformation other tl1an continuou tracing of inwvidual bed , can be u ed. Deformation hown in the ea cliff of Puget Sound are onl G/acioium of th Puget (rllntl RcO'i01i 203 ------local. though httrpl ~ a cent d in p1uc and by far he lar r numb r of expo arc i en ugge ·ti n of i turb occ-. lint~ ver influence the e m v ment may lrnve hod i.i1 hupin the topogrt phy and in tennining the ('on uent drninage, it , •. 2S. lDtert:laclal Dre.1011 e Patt r11 ot tba Adnur<r Pia.In, pro ably wa not reneral. The third factor thu nppar ntly i negligibl . ( 4) Om T TIO.N OF TUE TaouGHs Oll' PuGET ouND. The o:rienttl.tion of the v Hey of Puge ound i ob,,iou ly the factor of greo.te t importanc in a recon truction of the inter- 204 B'Ulll!tin No. 8 Washvngton Geological u1·v1MJ glacial drainage sy tern. It mu t be conditioned, however by consideration of (a) relati e depth of trough (b) relative len!l"th (c) 1·elative w:idth, and (d) the exi tence of trou"'h conte.ming fre h water or with floor above ea level. The fifth and last point mu t al o be considered in thi connection ; namel , the rela ion of deposits of Vashon till to the trough . B construction of bathymetrical lines from the ounding on the U. . Coast urvey charts of Puget Sound (Plate XXIV) the form and proportionate size of tho e part of the trough no,v below ea level are well shown. For the por tions of the trough above ea level the proportions are ap proximated by 20-foot contours on the e chart and are cor rectly delineated for the Seattle, T oms. and Mount Vernon quadrangles on the topoarapbic map of the U. . Geologic(d urvey. The e map and chart and a field tud. of the entire region are the ba i for the election of certain trough as hunk channels, and the groupino- of others as primary or econdary tributarie . (5) R£LATIO.Ns oF V.t.sHoN TILl. To THE T11.0uGas. The detailed examination of nearly every trough ha hown that the Va hon till mantle their lopes down to sea. level at lea t truncating the edges of the horizo.ntal Admiralty tratn. (Se Fig. U.) Tbi position is entirely in harmony with the fir t two topics d-i cussed and elearl shmv the trongbed topo graphy of Punet Sound to be pre--Vash n in origin. RECO • TB CTtON OF TIU: Dll.A.INAGE P TT.Ell.N. Briefly wnmeriz d the interglacial di·ainage tem of Puget Sound ou b of the Strait is elieved to have consi ted of three river ; one flowing north to the valley now occupied by the Strait of Juan de Fuca and two flow:ing south to the hebalis River (Fig. 23). Admiralty InJet is th trunk val ley of the north-6ow:i11g river ( 11..dnnira7ty River) . and Hood ruia.1 i the main alle of the western river ( ifatloclc Pathr oy Ri1;er) di charging to the hehali . The main poTtion of the valley of the second soutlnvard-flowing river {Gate Pcithway River) i thought to be largely obJiternted by Va hon moraine Glaci.aticm of tlip Puget o-um.d Region ~05 and olltwash ac umulation , but to have la.in b twe n i qual1y Reach and th wn of Gate, pa ing th1·ough the Gate Path way to the behali . '!'he lower portion of the Hood Canal river througb the Matlock Pathway i thought to be buried deepl in a. similar manner by deposits of Vashon drift. ( ee k th map, fig. !3.) It wa note earlier that he weake t point in the recon truc tion h re advanced j the ab en e of data on the depth_ of the drift in these two pathway . The ugge ted recon traction must remain hypothetical until deep borings ba,e been made in one of the e pathways. t the same time t11ere i o much evidence corroborative of the view advanced thnt thi recon- tru :tion ha been ventured. The pattern ecured by gr uping the trough of Puget ound int thr e different :river .Y terns has ome incongruous el ments though in aeneral it i harmoniou with con equent drainage on the AdmiTalty drift plain. THE GAT'E PATHWAY R rYElL remnant of the former trunk valley of thi river proba ly ist in the trooghed por- tion of the i qually River valley, between the mouth of the river and the bead of Mc.Alli ter Creek. A broad pre-Va hon valley e..xtend here about five miles outhward from Puget Sound. Early in the hi tory of Lake Ru ell. th i qually River mpti d into tbi valle , building the herlock Delta. on the southeast margin of the then exi ting bay of the glacial lake. Thi delta -partially obliterated that -portion of the in terglacial vnll , ~ l1ich had previou ly remained because of it position north of the zone of g1·ea.te t depo ition. The remaining portion of the trough lying north of the Sh rlock Delta ( ee Plate XXIlI) i amply proportioned for n trunk alley fo1· the regjon bdie,•ed to ha e been tributary to it. Toward it, th Carr lnl t (Hender on Bny) and a e 1n1et ( 01th Bay) trough converge, deepenin o- und widening like normal on equent t.l·ibute.rie on n. loping plain, and to them in turn mo t of the minor trough and valley of pre- !06 Bulletitn No. 8, TV asl,.ington Geological Survey Va hon origin also converO'e1 de pen, and widen.. A. study of the bathymetri a.1 line on Plate XXIV will show this clear] . In this outhern portion of Pug t ound which is the original Puget ound of ancouver the average thiclme of the Va hon till exposed in the ea cliff , doe not ·ceed 10 feet. It i locally thicker .in end 01· lee end deposit. as on Hartstene Island (See PL Fig. 1), outh Head, and el ewhere, but tbe evidence i- overwhelming that the interglacial topo- F10. 24. North bore ot Hnl a 'Passngc, sbowlag drumUnold. t!H l'ldges trun cated by se.e. Cliff~. Drawn .trom n pbotogrnplL graphy of thi portion of the ound basin lies now almo t a it did before the Va hon glaciation. There are many mjnor bay and inlet in this region, of which Wollochet Bay on Hales Pa age and Vaughn :Bay on a e Inlet are typical examples of large ize. In such valley the Vashon ti.JJ entirely veneer the lopes n.nd de cend to ea level with long smooth lopes. W'he1·e in pla e these even-flowing outline are cut by sea cliff , Va hon till 1 everywhere e}..-po ed at the top with tn.ined Ad miralty sediments below con t-itut.ing the real relief features. It i evident that the e minor valleys ant date the Vashon glacia tion from which they have received a veneer of £re h glacial till over t} e weathered and stained mface of the interglacial topo graphy. Hale Pa sage i a drnwned cro -trough of the old river system the former divjde in it probably being nea.T the w t end. Almo t at right angle to the direction of glacial movement, it show an interesting modification of the Vai;hon till venee.r Glaciatfo,n of the Puget Sownd Rcgum, 20'1 a modification which con titute the di tingui rung topographic feature of the pa age. The north slope bears many elongated drumlin-like ridge de cending toward tide wate1· at right angle to the length of the trough. (See Fig. ~4.) A few exj t on the 011th side al o. ( ee Pl. XVIII, Fig. fl.) At sea level the e rounded ridge are truncated by ea cliff , and are bown to be ompo ed entirely of Va hon till The summit FtG. 2ti. Cour11e of lladl11tl.Dg TUI Rlages nbout Wollocbet Boy. Arrow ln· dl~ate the rli:1ges. of the bluff along the north side of Hale Pa age thus ha a. calloped appearance jn section as shown in figure -4.. In the angle between Ha.le Pas age and WoUochet Bay, twelve distinct, trunca ed ridge of till are to be seen along the hore. They appear to radiate somewhat from the higher lund in thi angle as though in de cending ,the north ]ope of the pa age ba al ice wa deflected by the valley of Wollocl1et Bay. (See Fig. fl5.) A few minor alleys opened northward to ard the ice which overwhelmed them. Three such valleys lie side by ide on the 208 B·ulletm No. 8, Washi111gt01i Geological wrucy ·outh sbore of an Inl t (Henderson Bay). The northern tip of each peninsula between the drowned a.Dey i a to end depo it of Vashon till. The till thin out and it ba e ri from ea level with approach toward the mafoland along the length of the penjn ula until the bluff .po e only pre-Va hon material severely crumpled by the overriding glacier. outh ead is the mo t con picuou of the e to , end accumulation of till. The ori nation of Eld Inlet (Mud Ba ) Totten Inlet ( y ter Bay), and Skookum and Hammer ley Inlet i appar enUy anomalou -for on equent drainag on this portion of the clmiralty drift plain. However, incc each i the di·owned low r portion of a trea.m valley de cending the north . lope of the Blnck Hills their orientation doe no violen e to he hypothe i . Budds Inlet does not I ad back to a valley in the Bia k Hill ·. Its our e i directly north and appear out of harmony with the re tored Gate Pathway trunk river. But low rock hill lie between the head of thi inJ t and Little Rock and probably de id d the original consequent drainage whi h produced a northward-flowing tributary to a outhward-flowing river. The cour e of the trunk tream aero Thur ton ounty to the Chehali River can be outlined within (airly narrow limit . From the vicinity of Sherlock, it probably flowed southwe t toward the location of Offuts Lake thence along the a--rea now bearing Rocky Prairie, pa ing lo to Grand Mound on entering the Chehali . Practically all other route are clo ed becau e of the known existence of bed rock or dmiralty drift w abo e the channel level. The crucial region for the future tudy of th' que tion i the we tern part of Rocky Prairi and the terminal mora· e from three to five mile we. t of Teruno. The mo t con tricted portion of the entire valley was here, rock outcrops b ing ·known within 2 or ~Yz rnile of ea h oth r, between which the stream mu t have pa ed. 1nce the ystem of interglacial valle that di char.,.ed through Gate Pathway is now in open connection with dmir alty Inlet, direct evidence mu t be pl'e ented that a divide exist- WA 'IItNG . • Gr. 11. IC..U, • (;ll\"Y.Y Bl'l.l,ETI-S !so. Pu.n: . "Yl 11 F10. 1. ashou Tlll ea lift ul Ti11 of ap Horn. Fro. 2. Drumllnold l<'orm o.f Vu hon Till on • o · 1 lnnd. Lon rJtufllnul nxe,. trnu \"t1r~e l lhl" ll'IIJ.;"(h f (I I l' SStl "1 \ lu whkh tlH.!,) ll+ •. Glru;iatioii of th P1,1,get Sownd Begfrm, 209 ed between the Admiralty Ri,•er and th Gate Pathway River previou to the Va bon glnciution. hould this evidence fail to be ati factory the entire h rne well may be rej ted 0.1 too tenuou for eriou con ideration. The arrow , near 'l'acorna, uniting the trough of the Gate Pathway RiYer -with tho e of 1the Admiralty Rivel' cro e the suppo ed fol'm r divide at about it narrowest place. A tidal range avel'aging 16 feet for the inlet con titutin"' Van- ou,·er's Puget ound result in a current of si - mile an hour through_ the rarrow with every change of tide. ndonbtedly t}u urrent j widening the pas age and perhap deepening it. All indication are that the arrow ha been widened and de pened b tidal current ince the reti-eat of the Va hon ice. The pa age i a mile wide, and no w-ind wave of imp rtanc an develop on it, yet -it wall a.re a te p a the .A,.dminuty and and gravel will tand, and much of them is bare cliff face. nJy the surging tidal current can b re pon ible for their notable dev lopment in a water body o narro\ . The maximum depths of th Nu.rrow i O fathoms. olvo (Wet) Passan-e and Admiralty Jul t, a few mile north a.r 65 and 100 fathom deep re pcctively. Fi e miles outb of the a.now the deptb i again 100 f,:ithom . Though glacial ero ion probabl ha had ome pa.rt in this deepening both nortl1 and south of the arrow the arrow is much too ,hallo\\" and constricted even in its pres nt enlarged condition, to be on idered a trunk channel connecting troughs to the north and outh f it. The relation of t.he Va. hon till to the 1arrow· Valley form the final argument fo1· the existence of a pre-Vashon divide at this place. 1'he sea clifts 0£ practically all inlet of Puget Sounu fail to reach to the top of the valley slope , a more gentle slope covered with ashon till lying abo e the top of the cliffs. In place the Va hon till d c ud the ide of the valley to en. le el and theoreticall did o originally for aU inlet . ave work ha ince teepened the lower portion of the ide of the trough and removed the veneer of till, leaving 210 Bulletin No. 8, Washington Geological Survey it capping the section and covering the lope above the cli:ff , In the 11,rrow , the cliff reach nearly to the height of the urroU11cling land, and in the Point Defiance ection, on the ea t ide of be arrow a few fe t of Vashon till con titute a flat over to the ummit of the hill. The i11terglacial hill no1,th of Point Fo click which j at the junction of Ha.Jes Pa age and the a now , ha · a long gentle lope to Hales Pa age on the outb cover d with , a hon till, while the ide ow-nrd the arrow j abruptly truncated to the top, "\ a hon till overlying the tra.tified utwasb of Admiralty age. Figure. 21 ·pres e this relation, the ob en•er looking we t from the a.nows along the trough of. Hales Pa age. From such relation , it appe r probable that at the be ginning of the Vashon glacintion there was onl a. mall valley at the ite of the arrow perhap tributary to the Gate Path way River. A low divide at it head wa cut a 1·0 s during the Va hon. epo h. A considerable part f uch inc:i ion wa produced probably by di charge from the hypothetical lake which existed during the advance of the "\i a hon Glacier. When / Lake Ru sell level gave place to the po t-Vashon marine ub mergcnce, and tidal curr nts we.re initiated aero this divide, hei1 ero ive owe.r i tbourrht to have been sufficient to com plete the trough to the pre ent proportions. THE MATLOCK PAT..t,n Y Rxv:1m. Evidence for the former exi tence of a 1·iver flowing from the Admiralty drift plain through the Matlock Pathway i le definite than for the. ate Pathwa: stream. Theoretically dmiralty outwa b hould Jmve pa ed tlil'ough both brond valley in the manner of the Va hon outwa h of later date. But it doe not follow that both val ley would drain the r gion afterwArd t.he Va hon filling b ing a ca e in point the Matlock Pathwa being left 300 feet rugber than the Gate Pathway. The trough whi h are connected with Hood anal, and which 1ue with little doubt tr~ valley of the interglacial epoch of erosion afford th mo t uggestive evjdence in favor of the exi tence of the hypothetjcal 1·ivcr of the 1''.!atlock Path- Glaciatimi of tlie P,uget oumd Region 211 way. The -valley of the Great .Arm of the anal which joins th a.nal at it outhern nd, i a continuA-tion of Union River valley, thi · h·eam b ing the ucce 01• of the pre-'\ a hon river which ga e origin to the valley. The broad deep valley of the Tahuyeb River a. tributar to this arm, i imilarly oriented toward the outbwe t a normal po ition for con equent tribu tarie on a southward-sloping plain. kokom.i h River valley, the lower portion of which i of inter glacial age -is likewi e headed toward t::he Matlock Pathway. The Hood Cana.I trough continue outh for three miles be yond the head of tidewat r and there top abruptly with the outwa h and morainic accumulations of , o.shon age apparently damming i from further e.~tension in that direction. Dewatto Creek occupie another tributary valley of intergla cial origin correctly oriented for . outhward flow of the trunk tream. This arrangement of tributary trough i found a far north a Qu.ilcene nnd Dabop Bay. Hood anal trough it elI fail to harmonize with it tributary trough in deepening and widening outhwud. It deepen graduaJJ from botl1 n rthern a.nd southern extremities to a ma..x.imum dept11 in th middle. uch cannot be due to original stream ero ion. El where in thi paper it will be explained a a re ult cg , a~hon glacial era i~n. Whether due to tin or to cru tal movement, whi hi the only plnu ibl alternative view does not concern u here. The ea Jjlf e tion in tJ1e northern part of Roods anal fail ignally to indicate an interglacial divide as at the ar rows. From the tip of Toando penin ulo. northward to Port a ble th ea tern lop of the anal are low and bear a cover of a hon till with characteri tfo flowing contours. The till here attain a mn..nm1Dl1 thickne of more the.n 50 feet, and Admiralty mate.ria1 i ~ldom expo ~d. A more favorable tretch fo1· tJ1e location of an interglacitd di ide i between Port Gamble and Hood Head where dm.i.ralty edimcnt are more common in the bluff , and where few gentle lope bearing Va hon till exi t. flUl Bul.letin No. 8 Washimgton Geological Survey certain feature of the region of Foulweather .Bluff rend r the location of an interglacial divide difficult: indeed mak it problematical , hether any uch divide ever exi ted. It i the occunence of 'through valley , ' trough which appear to have cro ed the ridges b tween Hoods Canal aud Admimlty Inlet, though not to ha e been very deep, being more like con iderahle notcbe acr the bill . uch ar (1) the trnugb containing the P ul ·bo channel of Lake Hood, (fl) the valley aero the penin uJa ju t outh of Foulweatber Bluff, and (S) the valley w t of Hood Head. If formed by interglacial trcam erosion they apparently must be referred to head, ard ero ion of tream on oppo ite ide oi a divide. The ballm ing of Hood anal about FouJ1 ea her Bluff ac- cord with the conception of a. former divide in tm re ion, but hallowing of the ame apparent character exi t at the mouth of Adrnirnlty Inlet wher without doubt a principal drainage way to the Strait formerly exi ted. The , hole region must be treated at pre ent a one too greatly altered during Vashon glaciation to permit the interglacial topography to be deciph ered -with tl1e degree of succe po sible farther outh in the Sound. TRE ADMlD.ALTY RIVER. Thi river sy tem uffered mo t from the Va hon glaciation. (1) Ero ive a,ction of the i e in the pre-e.xi ting trough wa greater becau e of it more n rth ern. position and becau e of the greater capacity of its trunk valley. (i) Vo. hon till i thfoker than in region farther south in ome places attaining a thickne s of 100 feet. The evidence bow ver is convincing that the reatest f h inter glacial rivers of the Admiralty plain flowed northward tlu·ough the valle. now oc upied b dmiralt. Inlet. The Admiralt River y tem i widely at ariance wi h a con equent tream pattern. Bathymetri al line and the ea cliff ection make it appear tbo.t the Colvos (West) Pas age ·rj er flow ed south po 'bly from Dog6 h (Liberty) Bay, and vary probably from Blake I land at lea t,. to Tacomn., there joining the Admiralty River and completely rever ing j direc- Glaciaticm of tlie Puget ownd Region, 213 tion of flow, flil impo ible thing for con equent drainage on an aggrad d plain. The D e Inlet and W hington arro\ tream also fl.owed outh to Sinclairs Inlet, which \l'Wi tributary to the Colvo · Passage ri.ver. inclairs Inlet an cD.l'Ved th minor vaUey whicb today con titute th indentation in the i land oa t line. The 10, 20 and SO fathom lines ff the Cfl. t bore of lhe i land atro1·d fu1·ther i.nfornuition on thi ubj ect. Blakeley Rock which lie off the mouth of Illakele Harbor i situated at the tip of a ubmergcd divide continuing out from ing Point. The Eagl Harb r drown d any continues outb from the mouth of the harbor to lhe Blakele Hubor vnlle. , ithin .Blakeley ock and the ubmerged divide before entering the major trough of .Admimlt Inlet. ( ee Plate X ~ . ) Thi di po ition of tLe ubm rg d contour ha.rmonize perfectly with the concepti n of origin of tbi topograpt1y b tream era ion, and can hardl be explain d othet"wi e. Tbe great iocrea e in gradient ju t after union of the two valley hown on Plate XXIV i due to deepening of the main trough ob equent to d velopment of the e minor alleys. It will be dealt with pres ently. It j evident from the pr ceding paragraph that the problem of the interglacial drainage ystem a lea t north of the ar rows i highly complex and till far from solution. Careful and d tailed e."amiuation of the trough b future tudent shouW throw more light on th ubje t. -1\CATURITY OF 'l'HE INT.EltGLACL\.L ERO ION. By the clo e of the Puyallup jnterglacial ep ch in Pug t ound the b:cam of the region had brought the Admiralty drift plain largely to a condition of lopes. The broader plateau portion of tbe drift of Puget ound at p1•e ent are due u ually to depo ition of Vn hon till and outw h, Willi ha well hown for the Tacoma quadrangle. Few 11.at-topped clivide of the inte.rglacial topography with a width of more tbo.n two mile exi t in the region. INTERGLACIAL DRAINAGE ORTH OF THE STRAIT OF' JUAN DE FOOA. The extent of the AdmirnJty drift plain north of the moun tainous pur interrupting the ho.sin ha not been ati fac t01·il determined. ontemportwy drift deposit were laid down ~16 Bulletin No. 8, Washitngton Geological Swrvey in the Whatcom County lowland a.nd were eroded du1·ing the interglacial epoch by the ook ak River and other treams. Pot-Vashon m1:n·ine and alluvial depo it in the e interglacial vall y have produced the fertile farming land of Whatcom and Skagit Counties. THE "DEEPS'' OF PUGET SOUND. The soundings on the two Coa t Sur ey chut of Puget Sound how a number of remarkably deep depre ions in the bottoms of the major trough . ( ee Plate .) They are elongated with the length of the trough in all ca e and curve with the trough where located at a bend in its a.xis. Deformation j totally inadequate to e -plain them and their ituation in tream formed valleys give no clue to their gene i . They bear a definite relatfon to the form of the troughs, however which throw much light on heir origin. The following li t tabulates the important data for each deep. nrtt..1rr1~ • ·o. 1·1. II' XIX Fi . 1. Vashon Till ea II.fl', Brl c Point. outh .Elnd of Hnrlsl n C land. FJG. -· \ ashon Till n lnrrow ton I lnDd, Admlrtlltr lnl t. Sit111.1«011. ,·ornl. t11r. Drpth, Deyl/1 Na.me of Docp. Bofo,o R.1111. B0008 CANAJ.,- Hood11 Culal deep ••.•• • •• • ..• 1 South of two l'&lle111 nolLlDg I Leoirtb lndelllllte, w1dtb balf of I 05 fathom~ from Uw north, Cao&!. (570 ft.} Dabop Bay deep •...• • .•• • • ···1 S0ntb or two v11.11e,·s unJtlDg I t,;Joo Led, 8 m!. long .••.•.•• • 1 10~ fatJJoms "-0 Cn tbom• froro north- Br sJde ot coo (61:ltq. (180 ft.]. slJ'Jcllon caused b)' T'ulaJI Pt. ~ frock). ;;·.... Browns f'Olnt deep .•..•• • ...• onslTle&Jou I.ti trou&b chldlY 68 fathom~ above irea level, cau,ccl by high 878 rt.). j" blul'fs ot Admiralty material. 0 Bood• Dud deep •• • • .. .••.••. onrrletlon caused bf Etoods 78 tatbolll 13 talhOllll Beail loter:glaclal hll (438 lt.) . 178(-t.). -::,-- .ADMIRALTY TNLET T,ngoon Pt. deep ..•.. • •.•..•. 1 Co.nstrlctloo aJ>ove sea lewl I),!' I Genii\! "lo.l)ee t,elow &NI. level, au 1 104 !alhon1e 24 Cntho•n~ "'t:I blgh bl oft' or A1hnlraJ ty 1110.- ezccpllou to rule. (62~ lt.). (lH ft,). terlol on WbJdbey lel11od. ~.... S. · c102 rt._)._ ....i,S) 4 Daptll Na,m of Deep. B~tuatian.. Fonn.. Mae. Derrth. Be-1010 R/111,. ADMIRALTY I LlilT ooUoued. Point PuJly-RobLDson Polar d • p on trlctlon by two proJcctlng lillongate with max.Lmnm dcptb Pt. Polly, 27 rothoms points, oue ot acb end. ot cncb end. 127 tu. 702 !t. (162 ft.). l'L Robinson 123 tn. 78 fL 2,'.I fathoms Mld·l(lllbrl:h, (1:1 rt.). 111 tu. 660 ft. OLV PA GE- Colvos Pnssuge . • • . . • . . . • • • • • 'o CODlltrlcllon or nnltlng vol- Very l!longate wllb trough.. • . • 06 fRtboms 36 fotboms I ys. pens to 70 tatborus (396 tt.). (210 ti:.). west oC Bink I I.. 1vlllch CornlS a co1U1trlctlon. POS ESSTON OUND- [{aodall Folnt deep...... • . . Constriction by subm rged sn.11- 104 t11tl\oms 4 fathoms o.ut. (824 tt.). (24 ft.). Po cflSlon II call! deep. • . . • . . . • on trlctlon below sen level. ... 127 !atboms 27 !nthoms (702 ft.). 1102 rt.). Mu.kJlteo de p Constriction by olnt lilllloL 10~ .tatbOms 10 fathoms Va!lcy narrows. (62Ht.). (60 tt.). SARATOGA PA AGE- amnno Be.ad deep...... Constriction t,y aocly Point ... , 101 flltbom 11 tnlboms (008 ft.). (60 ft.) . Point Lowell deep...... onstrletton by two opposlt 78 (11tboms 1 rat.horns points. (468 ft.). 108 Ct.). SOUTH OF TB.ID NARROWS- Day Isl nod dce(I...... Comrtrlctlon by pre-Yosbon 11111 . 54 tatboms 14 fathoms {S24 Ct. . ( 7'1 tt.). Ketron Island a ep. . . • . . • . . . . Con trlctlon by tl1lll lslnncl, m1oni;ote, gcadually sh11llowlnii: 02 tnthomij 60 fathoms which Is an Int rglnclo1 blll, nurtbworcl up Cllrrs lolet and (612 ft.). (860 -rt. I. and by n. narrowing of Inlet. southward along NI quolly Reoch. Glaciaticm, of the Pu,get Sou11d Region !19 The above co.ta.I gue bring· ut the clo e corre pondence of deep to con t.rjctions of the troughs of pre-Vnshon 01·jgin. The com•er e relation i al o largely true; that no p1·e- ashon con striction in a major trough i without an accompanying deep. Another relation of these deep to the pre-Va hon topography i tlleil• o cun nee at the junction of two outh,rnrd-trending trOUO'h , These deep places in the Puget ow1d trough are refened to erosion by the nshon Glacier of the ha in. The special conclition for their formation wa the pa age of he ba al ice through a con tricted p01·tion of a rough which otherwise all'01·ded free onwa cl mo,•cment or , hat j the ame thing in principle the rowclin of ha al ice from wo troughs into one. uch condition houl MINOR RIDGl 'G OF VASKO. ORIGIN. ote ha already been made of rounded till ridtr , oriented in the direction of gfocial tllOYement and omp THE OLYMPIC MOUNTAIN GLACIATION. In chapter II the re1ation of the Vashon Glacier of Puget Sound to the Skokomish Glacier was discussed, and it was shown that tl1e greater ice mass pushed op into the lower end of the Olympic Mountain valley in the face of a descending local glacier. Theoretically, with the oncoming of glacial climate, glaciers from the Olympic and Cascade Mountains would descend to the Puget Sound plnin before the Cordilleran ice sheet entered the basin. The Skokomish Glacier then originally may have extended some distance farther down its valley, and the arrival of the far greater ice mass crowded it back, or overrode and destroyed its lower portion. No superposition of Paget Sound till on Olympic till is known in the Skokomish Valley, but a locality a few miles north on Hoods Canal affords a section that. is to the point. On the east side of this inlet, midway between the mouth of the Lilliwaup Creek and Rama Hama River, a dark-colored till overlying the weathered drift of Admiralty age is exposed in a sea cliff. The till is unlike either Admiralty or Vashon till any where in Puget Sound. Its color is far too dark, its pebbles are subangular instead of rounded, and it possesses no granite or other ho1ocrystalline rock, Fine-grained, dark-colored rocks prevail~ some being basalt, $Orne metamorphosed sedimentaries. P ebbles with a bright green vein-stuff, and pebbles of bright red jasper are conspicuous in it. The till js very firm. A bloclc 2!l2 Bulletin No. 8, Wa hiington Geological urvey e,•eral feet in diameter fe)] from a ea cliff for a di tance of 40 feet without di ruption came to re t on the beach between tide , and ha ince been carved by the wave into o. tack 10 feet high. The harncter enumerated tamp thi till a Olympic in origm. It fr hne indicate a hon u.ge, and it po ition directly abon the old weather d dnuralty drift bows that deployment of OJ rnpic glacieT had .filled and cro ed the p1·e- Va hon Hood anal trough before. the 01·dilleran ice en tered the field. The po ition of th.i till, in failing to lie oppo- ite a valley from tbe lympics i evid nee that a piedmont condition of the deplo:ed OJ, mpic ice wa nttl,ti:n d to be later destro ed b the ordilleran Glaci r from the north. everal expo ure about the mouth of tJ1e Du ewallip River bow an Olympi till po e ing th ame c,,cneral characte1·s found in the till above d cribed. It underlie the Brinnon Delta, a.nd appears along the hore for a hort di tance north of the mouth of the va.11 , aa,ain indicating a deployment of Olympic ice beyond the mountain before the ordilleran inva ion. Though Puget ound Ya h n till ha not been found to oved.ie it the o currence of pebble · of gr nite in the Dasewallips Val ley, two miles above it exit from the mountain , proves tho.t Puget Sound ice crowded back that far o:ver the local ice. The la.ck of a ground moraine of the greater glacie1·, nd th scar city of Pu et ound drift ma erial in the Du ewallip Vall y may mean that the basal pol.'tio11 of the ice in the valley remained Olympic and onJy lhe upper ice of the Puget Sound Glacier wa pu hed up the valle . Till with pebble of granite Ji on the bottOiu of the Duck a.bush River valley lo e to it mouth. Here the Pug t ound Glaciei· c idcntly a· placed the local glacier in the Lower ,,alley at lea t. Granitjc enatic have be u found by Profe or Henr L ndes State Geologist for 25 or 30 mlles up the Elwha River valley, on the north rn lope of the Olympic . Thi i further ,ridence of th dominance of ordilleran ice on the lowland. Gla iation of the Pugat 011nd Regicm i~S TEE CASCADE MOONTAlN GLACIATIO .. • Willi· nnd tHit.h have identified 11 plane tract of ground morain in the ea tarn part of the Tacoma quadrangle a the depo it of a piedmont glacier upplied from the Ca cade Moun- } tain to the east. '!'his they name the ceo1A Glacier. They also consider that a broad glacial heel pread out from Mount Rainier and met the ordilleran ice on the Puget Sound drift plain. The pre ent tudy ha failed to erify thi latter con ception as hn been noted. It i true however, that Va hon outwn h in the outhern part oi the Puget ound ba in in many places bear a large proportion of 1\Iount Rainier lava even as far ,l'e t as the Rn.inier-Wall·ick Prairie drainage channel, eroded in the earli r-bu:ilt Tenalquu.t Prairie ( hap. IV). A terrace of the glacial isqunU River is b·aversed for two miles out of 1\1cKenna by the road to Eatonville. Its urface · lit tered with coar e material, hu·gely of Mount Rainier la a many fragment being four fe t in diameter. Granite i not abun dant. scent from this terrace i to the ground moraine of the Puget ow1d Glacier which i h·ewn with large, angular bowlders of granite, typical of Puget ound drift, and among which not one b°'dder of Mount Rainier lava was found. The wl'itex s ob er ntion in the Ca cade Mounts.in have been limited to the Snoqualmie ru1d edar River valley in neither of which ha a liue of contact b en found between Puget ound drift and a. cade Mountain drift. edar River valley be.low Barne ton i of po t-Va hon origin and the tream has been uperpo ed on an old drift topography doubtles of Puy allup interglacial age. The Vashon outwasb deposits here are o deep that little has be n made out of the glacial hi tory of the region. The Admiralt ru:ift plain i thought to be recog nized in the great drift filling which extend back into the moun tain alleys. Cedar River appear to ha,•e flowed originall to the Sno qualmie, but by glacial derangement of the drainage to have been turned outhwe tward th.rough a narrow· mountain-walled 224 Bulletin No. 8 Washinigt011 Geological wn•a y valle to enter the Puget ound drift plain at a more outher-n point. The . tt·iking featur of th noq_ualmi River valle jn the mountain are the lower fall !26 feet in height and tl1e broad flo dplain which trctch back from th fa.Jls for ~ven r ile r o up among the mountnin.s. The vi w of tbj floodplain from the ummit of Mount Si, 3 700 feet aim . directly above it, embra e a remarkable as emblage of tream meand 1· , ox bow lakes and ere centic wamp the wh le bein mo t trik in{)'l contra ted with the cntaract who abrupt plwige uc hi aim]e loiterina ourse of tbe river. The low r part of the floodplain de cribed is bounded by bluffs wnich ri e to the rugh plateau of drift alon{)' the we te1·n foot of the a cade Mountain the noqualmie here having inci ed it dcepl . o eJL-p ur of t1, tructure of thi plat au of drift ar known. The que tion of it age mu t be approached from another point of iew one that in olve the origin of he falls . ..,. Snoqualmje Ri er plung o, r a cliff of linn who e outcrop ri ] 00 feet or o above the fall on he outhern ide. On the north m ide of the f 11 i the truncated end of a mora.iruc ridge which cro e the valle in ]in wjtb the cataract. E -cu- ation for a power pla.-n t and a railwa rade have afforded in tru ti e ection of thi moraine, from whi h it i evident tfoi.t the moraine i the au e of the de:flection of the rive1· to the south id of the valle . Thj deflection ha cau ed the tream in it down-cutting to become uperposed on a pur of the pre Va hon noqua.lmie "'\ alley , bicb ha given ri e to the fo.lls. The presence of thi moraine aero the valley, and the la k of down-cutting at the fa.U have au e the broad aggraded floodplain which i so out of harmony with the cataract below it. '/... number of great terrace-lik surface abo e pre ent valley floor. can be een in the valley of edar River and the South and Middle Fork of noqualrnie River from the mountain sum mit of the region. The e terrace appear to lie in a common plane, and have a perceptible desceo we tward. Grouse Ridge \V S 11 INOT0i\ it~ L t Af1 • U\flJ\• PCu\Tta: XX Fi •. 1. Dro ~·ned Vall r or hamber's r k a Low Tld~. ~lnrlnl• IH'II lJO tl'l'l nhov, lh~ ·t•n \ 1•r1• rou ntl nt X. rn. 2. Calli Polnl 1111 , an .Juan Csland. Wuv •-cul l~·n,•hr• on 011th,•rn 1,r lrh· tn 'I', 1l11twn•h 1111rr1n r1r ('llltlt• 1•1,lnr rnornln<' lo ror gerourul. Glaciatim of the Puget Sound Regum 225 one of the e 1fat-topp d a1·ea in the outh Fork Valley. It lie on the north side of the l'iver and is cro ed by the Ellens burg Road. t i compo ed of drift and apparently i to be corrclated with the depo it of drift in which the lmge excava tions have been made at Ragnar on the hicago, 1\1ilw11ukec a.nd Puget ound Railway, on the outh ide of the vall y. The e broad tract in the mountain valle , evera1 of which a.re known to be compo ed of glacial debri , probably can be correlated in a continuou profile of a former drift lilli:ng. uch an aggradation of gla ·ial drift in th capaciou valley of the Ca cad Mountains further probably can be correlated with the Admiralty drift plain of Pu et ouod. Though no . tamed 411.d weathered ediments have been found in the mountain val ley , thi filling bas been deeply and broadly excavated wber the :floodplain of Snoqualmie River above the falls now lie and in it have been depo ited t,1·0 or three rece ional moraines of a Vashon valley glacier, the terminal moraine o curring at the fall beyond the mountain-walled portion. o e"idence has been found to show that the Puget ound Glader ro, ded back into the a cade Mountain a it did iu the Olympic . uch evidenc is not to be e.~ect d since th glaciers from the a cade Mountains were of much greater mass than tho e from the maJler Olympic 1\Iountai:n . -8 CHAPTER X. PLEISTOCENE AND POST -PLEISTOCENE DIASTRO PHISM. SYNOl'SIS, ALTITU'DE DUR1NG THE ADMIRALTY EPOCH. 1:fonMENTs AND ALT1·runE DURING THE P uYALLlJl' Ei>ocR. ALTITUDES DURTNG 'l'HE VASHON EPOCH. TnE Gn.:ERALIS VA 1,LEY T ttAIN. T im CA'r'rLE P OINT Mo1tAI.NE. THE SQUALJCUM: D ELTA. SHELL--DEAil1NG Tn.L OE WtrATC011! COUNTY. PosT-VAsnoN CHANGES TN AtTrrunE OF THE R EGION. HIGH-LEVEL 1\'!ARINF. SHELLS IN SEATTLE. l\lLuI:ll.':E SH.ELLS ON THE Ric:ac1rnNn D ELTA. 1\i!Annra Su.ELLS oN TR:E SEGUALICHEW D ELTA. MA1tnn, SELLS AT RmR ALTI TUDES IN THE SAN J uAN Is1r ANDS. BEACH RmGES OF W HATCOM COUNTY. CHAMllEJtS CREEK AN1) THE STEU.ACOOM D ELTA, GENERAL CONSIDERATIONS. ALTITUDE DURING THE ADMIRALTY EPOCH. The known history of Pleistocene c1-ustal movement of Puget S0W1d begins with the retreat of the Admiralty Glacier. T he lower beds of the Admi_ralty sediments are known to contain marine shells at altitudes of a few feet above present high tide. The altitude of the land wo.s thus slightly lower tlrn.n at pres ent. Its attitude did not depart much, if at all, from that of the present. MOVEMENTS AND ALTITUDES DURING THE PUYALLUP EPOCH. Aggradation of the drift plain was completed while the land lay at this low level. Subsequent to tlie formation o·f tnis ter restrial deposit, regional uplift elevated western Washington at lea.st 1,000 feet above present altitudes. The deeper Puget Sound troughs produced by the interglacial erosion attest a Glaciation of tlu: Puget owrL-d llegwn 22'7 long duration of thi high altitude, probably ufflciently long to permit the d vclopment of a. graded condition in the val leys and the b (!'inning of vaJle widening. The duration of t.hls u fleriaJ expo w·e was ufficie.nily long to allow weathering to soften the gravel and till e..xpo ed at the sUifaoe. Limonite from oxidation of m:ficial material, was wide] di tributed by ground water in h deeper dmiralty gravel and au ed the taming which i a con pi uou fea ture of the porou Admiralty edi:ment in the ea cliff in the Sound. A duration many tim the length of po t-Vashon time was nece sary for the eras.ion and weathering accomplished during he Puyallup interglacial cpo h. The uplift at the beginning f the interglacial epoch pro duced local deforwalion of the Adminlt. ediment . Admir alty gravel at tbe ea. t end of • o · ·land is faulted in place and lightl tilted. Deeply toin d Admiralty and in Mag nolia Bluff cattle Harbo1• i omewhat bowed up in the sec tion ju t south 0£ West Poio . The beds of the Quatsap Point Delta are fnuJted Jigbtl . ( ee Plate XII ig. ~-) V,niou other section how omparable deformation of the variou ediment compo ing th comple ma or the Admitu.lty plain. The great st d formation known in the Admiralty sediment i at the outh end of "Bolton penin ula. Th Admiralt til11 and its over1. ing gnwel and underlying cla are tilted to the northward nJ1d hav a dip of i5°. The movement which produced thi; deformation wa trictly local for the entire ea t rn ide f Bolton penin ula and lie we t rn ide of the adjacent Toando penin u1a are expo ed by ·ea cuffs and no hint of exten ion of tLi cli tu.ruance into them ho been found. ALTIT DES DURING TEE VASHO:N EPOCH, At the time of the maximum a hon glaci8Jtioo, the region tood at about it pre ent altitude. The time of lowering from th interglacial higher altitude ma have pre eded or been contemporaneou with the advan of the Vashon ice epoch; it wa attained at least by lhe time outwash reac.hed Grays Har bor at the moa th of the Cbehali . Tl1e bell-bearing till of the 228 Bulleti,n No. 8, WashilTl,gfm Geological 'wrvey Laurel moraine may indicate that lo a.Jly at lea t the ea had crept back up the intergla ial valley before the advancing Va hon i e had reached the northern portion o-f the ba iu. THE CJ-lElLU.I VALLEY 'I.'RA.l'N. The 'hehali Valley wa fill d by the Puget ound Va hon outwa h to a level much abo e the r ck floor and the graclicn in the valle tn1.in, de cribed in hapter II were adjusted to a sea level not fal' from t11at of the pre ent. The So-foot ter n e of gla ial gra el in th cit of Aberdeen at the head of Gra , Harbor po e es tream-bedding from top to ottom, with cro -bedding in place d · ending , e tward. n i pos i ble that Va hon outwa h built a marine delta in this protected ha but if so it ha been completely de troyed by subsequent change , A ide from the west rn terminu of the Chehalis alley train, no 1·ecord of the altitude o-f tlJe 1· gion wa left un il glacial re treat had opened tbe Strait o-f Juan de uca and Lake Ru ell had been drained. Outwa h gravels which except subglacially, or in delta , had never b en d posited belo Lake Ru ell le el in Puget ound now came to be ndj u ted to the e& le el of the Vashon epoch. The viden from thi i not as c nclu ive as might be expected but give a range of about 40 feet within which the sea level urel la . THE CATTLE l'OINT MORMNE, The material of the outhern lope of Ca tie Point Hill of an Juan I land bas the stratification of an alluvial fan. There i nothing in the tratification to ugge t that it was formed in tanding water. As e,.ii:po ed in the ea cliff the ubaerially depo ited trata descend to within 25 f et or o of high tide. Th ea lev 1 wa. evid ntl om what below tbi level at time of depo ition. In the bluff overlooking the city of Mt. Vernon, in the same latitude a attle Point, Va hon outw·a h gravel how tream bedding to the ba e of he ·po ure altitude 40 f e t. Though delta-bedding is present it occur only in individual horizonta) Glaciati TJ'!E SQ. ALIC lit DELTA. marginal river formed along the edge of the Puget ound Glacier a it withdr w nor hward from Squalicum :Mountain east of Bellingham. It ha.nnel i foll wed by the Bellingham Bu.y and Briti h olumbia Railroad bebreen oon and Belling ham, and descends we twanl to open out toward the bay in a bToad flat of and and gnw 1 in the northern part of the city of Dcl.lingha.m. Extrn h,e scavation and railroad cut in the valley of qualicurn reek expo e the tructure of this delta but the tratificatiao i not in an way co;mparable to the beautiful structure of ome of the Ltlke Ru ell delta . trata dipping award are common though of no great length or thickne . uch fore et be pos e no d finite up- er JiJnit y which the ea level may be d termined. tream- bedding o cur cou picuously at the top bearing andy trata with fine cl'o -bedding dipping scawttl'd. But ravels with rude horizontal tratification occur beneath the fore et bed , at a vertical dHance from the and too great to fall witl1in the tidal range of Bellin ham BrL . Beneath the whole is an ero ed lll'face of and whi h i a f.te b as the gravel above and doubtle belon" to the ame dcpo it. In the upper part of the gra v l is a p r, i t nt clay str/ltum one to three feet thick. Obviou ] tl1i i the deposit of a h a.Yily load d tream which flow d through the qualieum channel. The plain cau ed by this delta-like depo it ha an altitud of '15 fee . Fr m thi mu t be ubtrncted the variable thickne s of the top et bed to obtain the height of the sea at the time ( d po. ition. This wa perhap 50 feet above pre ent ea level. Horizontal and fore et bedding both are to be found within 30 feet of pre ent mean tide. · Tl1e sea cliffs of the northern portion of the qualicum delta plrun show 10-~0 fe t of c1ay at the top. ince thi is at the time level a the andy and gravelly portions it mu t be con- 230 Bulletin No. 8 JV ashington Geological St1Jr(Jey t mporaneou . It may be explained a part of the delta which during the la tage of growth wa not r ached by di tribu- ary current the clay ettli.ng in the till water. Thj on- ceptjon demand , how ver an nltitude of 75 f et for the ea 1 el. The qualicwn lta plain i bounded on th north by ground oraine which ri e 30 fee above i . a lift' ction bow fore et gra. el b n a.th th t-ill. The tiJl i probably the re ult of a light r ad a.nc of the Va hon i c while the delha as being built. The conclu ·jon draw-11 from th qua.li ·um Delta regarding , a level du1·i.ng Va ho retreat i tha thi plane la omewhere between 30 and 75 feet above pre ent mean ti.de. SHELL-11EAllING TILL O'F WHATCOM O .N'£Y, The ea cliff of the qualicum DelLJ.t and of th hore west ward along Be.llingham Ba di play two till heet eparated by brown and, and localJ by the o erriddeu portion of the delta. The ba al till i gra the upp r one i yello-wi h. The brown- tained ands are identical in color with the stained Ad miralty ediments. "Both till . a1·e more argi.llaeeous than is u ual for Puget ound and both contain marine hellis the lower one the mo1·e. large thin entire P eet n valve wa f und in the lower till. The topography ol hi area imni diatel north of the q_ual icum Delta, o erlyiug the hell-bearing ton la hwn mocky and po num rou kettle hole . It i a typical mora-in.ic urfa e. The intercalated fore e b d above de- cribed, afforded further evidence that tb hell-bearing tony clay i a true ,,, round moraine and n a depo i from floating ice near a. glacier front. The taine Va hon age produced by two ucc s i e advance , little hesi tancy n ed be fel in x laining imila.rly he marine hell bearing ton lay of the Luu.rel m raine five and a half mile north. The hell of th Laurel 1.nor ine 100 feet abon tide therefore do not ntei· oar pTe ent problem of the height of the sea level dming Vashon retreat. POST-VASHON CHANGES IN ALTITUDE OF THE REGI01. From the for croing imperf t dn.ta, Lake Ru sell appear. to have been betw en llO and 13 feet above ea level at its maxi mum tage, the plane of which now t ods 160 feet abo e tide. But the histo1·y of post- a hon marine o ·cupancy of Puget ound i complicated more than i indicated by thi videnc of an upward movem nt of S0-50 feet. It i obviou that a. check might be had on the , ashon ea level from marine trand i£ ince the la t glaciation there had been but thi upward movement. But the occunence of ma.cine shell oYerlying Vashon till up to nearly 500 ieet above mean tide, de troy all chBJ1ce of using uch a cb ck. umerous ob erver have reported marine h ll bed on wave cut terrace of po tglacial age 11 high a S0--40 feet in Puget ound. The writer has not d earlier the occurrence of marine ·hell up to 100 f et ab ¥e tide inferring from limited data that the Va hon ·ea l l 11' 0. at that nltitude. fore tudy of th region ha ·hown that po t-PI i tocene marine tl'l\n , re corded by hell beds, lie lSO feet nbov the levels of th PleHo cene Lake Ru ell and perhap !>?50 feet nuoYe the altitude of h Va hon ea. lllGll-LEVEL M.UlD.'E SHELLS IN RATTLE. Tlte u t occurr 'nee of marine hell at high levcl known at pl'e eat i on U1e we t lope of Queeu Au.ne Hill in the ity of eattle. The hell · a re betwe n Tenth and Ele enth .Avenues, directly we t of the end of 1\1cGra1 tr t. The lie on a lop ing terrace a foot or o beneath od nd loo e oil but above the Va hon till. The hell con titute an almo t continuous depo it b tween 195 aud ~n f et abo e tide. Th genera. $!8~ Bulle.tin No. 8, Washington Geological uruey Mactra {clam), Paphia (clam) Cardiwm (cockel) Natica (snail), Thais (periwinkle) Mytilu,s (mu sel) and Balamua (barnacle) were found. The amount and the com minuted na ture of the material the di tribution tbe relation to the ter race and the inedibility of ome of the species repre ented, ren der origin of the depo it by human or animal agenc very im probable. It i a true ea beach with the full tidal range rep resented. Dire t.ly aero the Interbay Valley from this occurrence, on ort Lawton Hill, a f w brittle h·agment of l'Yfytilus hell were found in plowed ground at an altitude of !e08 feet. o terrace exi t here. hell were found al o a; l 80 and 140 fe t above tide on the Fort Lawton ide of the lnterbay all y. MAlt!NE HELL ON THE lUORM'.O D DELTA, hallow cut along a econdary road wruch tra er es the urface of the Richmond Delta a quarter of a mile back from the edge of it de cent to the S und, ha re aled a b d of hell material largely comminuted, beneath the fore t floor. Shells of Balamus Cardiwtn, Mytilus fl. astropod and several other pelecypod were fou11d in thi . The altitude of the bed i 190 feet. A mil north of the delta on the andy floor of the channel which leads to it fragment of Bo.lam:U$ atica and Cardiwm., , 'th other unjdentined hell fragments were found at an a]ti tud of !250 feet. MA.lltNE SHELLS ON THE SEQU LICHEW DELTA. A few pieces of weathered ea shells we1·e picked up on the urfa of the equali hew Delta at an altitude of 190 feet. Alone, they ignify little ince they may have been carried there. The altitude, however 1 the 1.une a that of the bed on the Richmond Delta which is very probably in situ. MAJllNE SHELL AT HIGH LEVELS 1 T:F(E SA.N JUAN ISLA n>s. The e i land are composed so largely of rock that the com- mon b acb pe ie with heavy bell u h a the clam and the llVF))' Tllrr, Llil1'1N N . PL.I.Tfl XX! FJ<,. J. a 111J' ln oulh 111, an Juan lslnad, :llh I-look Ap11 nd d. F1 . 2. EnaL on Va hon round rora1n , n ar Port Gamble. Glaciation of the Puget Sawnd Region 2SS large and-burrowing mail, Natica are rare in the pre ent lit toral fauna. For the rune r a.son, the were lacking during the earlier higb marine levels. Occurrences of shells on these i land are limited to the mar hes and pocket of accumulated finer materials in embayment of the rock hill . The high t po tglacia.J marine h 11 yet known in the Puget ound country occur on rca Island. Ditching in a mar h on the old ap. Olden place near the quarry of the owell Lime Company disclosed mlllly clum heli in the cfoy and peat. The e were o friable tha they crumb1cd completely oo expo su1·e to the air. The altitude of the m11r h i fl70 feet. well on the propert of Mr. H. F. Pearmaul of Deer Harbor has yielded fragment of shell at fl.11 altitude of 290 feet th.is being the hi.,.be t occUl'rence t known. The material in which the bells ccur i. clay for the depth of the well IS feet. It i undo btedly a marine clay ac umulat ,d in a malI mud Bat near the old sea level. an Juan mid Lopez I land po. e s everal hell-beaTing !Dar he 11.t altitudes above 100 feet. Tbe Ile1LVel'ton Valley b tween Friday Harbor and R cl e Harbor i r ported to have yield d lam hell in many ditche . Its altitude i about 10 feet. hell A.Te found occa ionally in tratified clay on Lopez I land near Richard. on the hiD"hest occurrence being fo a well on Mr. W. F. Bolton' farm one mile north of Richard on at an al itude of mo fe t. The mo t onspicuous record of the former marine submerg ence of the an .Tuan Island is he terr~cing of Cattle Point Hill and out.h Hill. Di tinct benches are preserved in the od-bouod gravel on the outhern face of Cattle Point Hill (Plate XX Fig. ~) the two highest being ft40 and 175 feet above the a.djt1.eent ea.. outh Hill has a imilar bench at ~65 feet but none below. BEACH RIDGE OF WHATCOM COU-'.:\'TY. The broad plain of po tglacio.l marine and fluvial aggro.da tion which con tit-ute the fertile farming ountry of Wlmtcom County in places bear beach ridge recording the former ma- ~34 Bulletin, No. 8, JVashimgton Geological un1ey rine ubmero-cnce. uch beache are con picuous on be plain north and west o.f Lamel. The ai:e omewhnt irregular jn crest, and inclined to be duney aod hence are not u ed for ridge rnad . ome are ve1·y low and carce] to be dete ted. They are compo ed of clean brown and with rounded gnt.in . ru m rou thin, wavy earn or trata 0£ clay o cur in them, but no hell remains were found in them. The large t ridge ob erved trend northea t to uthwe t along the edge of a terrnce the ridge being !O f et above the plain on the north, e t, nnd 10-12 feet above that on the outh ea t. This ridge i cut in th1·ee places b the road between Ferndale And Laurel, and once by th Pacific Highwa north of Laurel. The ow· e of Tenmile reek i paralle] to the ridg . Beach ridges o.re numerou between Lynden and uma and are commonly compo ed of fine gravel. A ection afforded by one of these howed trata dipping westward obviously pro du ed by acer tion on the seawa.rd face of the beach. The higbe t k"llown occurrence of beach and on the What com County plain i ea t of E er on at an al itude of about 100 feet. It does not have the form of n ridge, but from it ur ficia.l po ition and fr edom froi11 cla it i be t explain d 11 a shore depo it on the ground moraine. It ontaio a peat layer in a position in entfre harmony with bench origin but difficult to esplain otherwi e. CHAMllEll CRF.EX AND THE TEILACOOM DELTA. The above e idence indicat tbat the region sank after re treat of the Yashon ic , tmd ha ri en ub cquently to 11.n alti ude omewhat g reat r Lho.n that po e cd uring the a hon deglaciation. It i not y t e tabli hed that the e movements con- titute the whole of po t-"'\ n hon diastrophism in Puget ound. Puzzling relation have been found between hambcrs reek valley and the teilacoom Delta whi h po sil,Jy may add to the din trophic hi tor . Chamber reek i a po tgla..cil,ll tream whlch ha deeply in- ci ed the teifo.coom Delta. Grave4 with foreset bedding, ha been recognized on both ide of the mouth of the creek valley Glaciation of the P.,iget oumd Region 285 and the delta plain i easily recognizable in the bluff umm.it on eitl1er ide. It eem evident that the creek valley mu t be po tgla.cial. Y t this alley is dro,vned for a mile back from the ound at high tide. ( ee Plate XX Fig. 1 nnd Fig. fl6 .) In itself ucn drowning might be the result of recent inking but the following fact need an entirely different explanation. On the outh side of the valley fully 1 00 feet back from lhe mouth, marine bell have been found at ,rn altitude of 110 :--- :' .tf I ,.;;) : ll.i Sfeilacoo ' --> Cl ; f Delta z: ,' f :::l : <..::, Top O(l U) : If$ :~ : i1 t.: ___r:,J _ E'IG. 26. Lower alley of Cbamhrr'. Creek rtnd Environ~. X- ccurrences ol .M~IDe bells, Drawn !rolll tbe U. . . G-. . bart No. 6-11.10. 2S6 Bulletvn Na. 8, Wcuhvngton Geological S'1M'Uey feet. Below th m and omewhat nearer the Sound though yet within the val! y heavy hell bed up o 30 feet in altitude are consp1cuou . The equence of event recorded in Chamber -reek valley i apparently a follow ; (a) Depo ition of the t ilacoom Delta in Lake Ru ell and risquaUy. (b) Ero ion of the lower portion of bamber Creek valley. ( c) Submergence in the po tglacial high marine tages. (d) Emergence to pre en.t altitudes thi falling hort of the immediately pot-Va hon al itude leaving the Chamber eek valley partially drowned. Since tl1e land during Vashon retreat wa 30-oO feet lower thttn 1J.t pre ent, and the ba e level to w}1ich 'bambei· reek valley ha been eroded wa lower than that of today, the above bi tory require the insertion of item (a1 ) An· uplift exceedin()' 60 fe. t before e1·0 ion of the bambers reek valley . .Before ace pta11 e of thi additional uplift and de.pre ion with a con idernble interval of ero ion antedating the marine ubmerg nee the hypothesi nrn ·t be veiified from two differ ent point of view: (I) Other occurr nee of marine shells in situ in postgla cially erQded, and perhap poxtially drowned tream valleys 1 ust be found. (2) It mu t e prov conclu i e1y that the lower part of hamber r ek mlley i not larcrcly an emba ment between lobation of the delta front. inoe neither ha been e tabli hed yet, the postg1o.cia.l diast-rophic hi tory of the Puget Sound ba in mu t ta11d for the pre ent a (a) depres -ion which sue reeded Va. hon retrea and ubmerg d the region to at lea t !t90 feet a.bo-ve pre ent ea level, and (b) uplift to pre ent alti udes. GE ERAL CONSID.ElRA.TIONS. It is of intere t to note that thi c1·u tal movement wa down ward after the retreat of the ice. not upward as wa the case on the Atlantic coast. It docs not fn thi in tance bear out the conception of i o tati adj u men t, con equent on deglacia.tion. ,.... . I _!./ I l.t. .. ' ~. - - ... - - ,- - ' ' - '" ------ft --- I µ_ . ,- _..._ I I f+ I I ,_ --A tih.td ~ r IJ I '" " ~ ' L -.., I ,..I r, ,- ,_ - "'. . 1-- ... - .I] -~ -, J ,- .,, ..... - I.,' .... \ I.J ~ ,r - l,~ liih- J ' ·--- ' I I I ' -"' ---·~ I ' I ' I -- '·' - 1-- I - --- ·-- -~ ~ ,_ ti il.. - ,- p >-- D~ ~ --r1- P::: Jl' rn. 2'l. ln~troobJc Mavt mcnta ot tlie Pog t oo od Bn tn slu c The glacial mas wn however, of relati ely light amount com pared to the ontinental ice- heet of K ewatin and Labra dorean origin. i\farinc hell on the luff of PuO'et Souod are 1·arely ac companied by wave-cut terrace . The 210-foot shell bed on Que Anne Hill lie on a fragment of a terrace, and a 106- foot hell bed on Hoods anal, ju t north of the Hama Ham a Ri er, o cur on a definite hen h. But the duration of th higher m1ll'ine stage appea to have been too brief for the development of ma.n shore line trong enough to per ist to the pre ·ent. A further evidence of tl1e brevity of the submerg eu e is the lack of tream delta at the marine levels. During the perhaps equally brief e. i tence of Lake Ru ell the b:eam were heavily laden with glacial outwa h, and deltas probably gr w fti.r more rapidly than at any . n equent time. Little warping or tilting of the r aion ha occurred during the e po t-Va hon moyements. The high t 1 vel of the Black Lake outlet of a.ke Ru ell i 160 f t. The top of the fore t beds of the Richmond Delt~ more than 50 mile nortl1, i 165 f et, and the upp r margin of the R dmond Delta O mile· northea tward, i 160 feet. These altitude have been deter mined with aneroid, and more refined mea urement may how slight deformation. Por general purpo however we roa.y consider the depre sion .ind uplift of po tglncial time to ha e been about equal in aU part of tbe region. The1·e is a final point regardjng the Plei to ene deformation of the rerrion which i intimate! concerned with the hyp thesi of the Admiralty inter 1~ ial river. It i the halJowh1g of Admiralty Inlet near jts junction with the Strait of Juan de uca where the oa ur,•e chart indicate a rocky bottom. If such 1,all wing i due to Va hon depo ition thi gives an unpn.ralleled thi kne of Va hon drift of at least S O feet, the inJet here being h Uowct· than the a erage depth farther outb, by that amount. The thicke t ection of Va hon till above ea l vel are about 100 feet. T his upposed depo it lie further, where ero ion in tead of depo ition, would be e p cted. The GlnciatioJi, of the Puget S0tt11d Regi "rky" of the Coast Suney chart, under lhis hypothesis, must be considered to .indicate n bottom strewn with bow1dery d rift. If tl1is shallowing is due to a differential uplift of the region, it should affect also the hills between the troughs. No evidence of such has been fotmd as yet. The time of the differential movement may best be placed in the Jate Puyallup or early Vashon epoch, when lowering occurred from the high intergla cial altitudes. T be depth of tl1e Strait must be considered he1·e also. The depth is 80 fathoms at Port Angeles, gradually increasing to ward tbe ocean, exactly as a stream valley would deepen, pos sessing a grade of about 9 feet to the mile. CordiUeran ice discharged westward through the Sh·ait, as well as southward into the Puget Sound basin, but has left no hint of its pres ence in the con6gurntion of tlae bottom of the Strait Valley. This valley at its present altitude is too high to have served as the outlet of the Admiralty River, though tl1e evidence that it did so sei·ve is convincing. Its present altitude may be due to differential mo,·ement of the Strait and Sound regions, or may be ascribed to a drift filling which lws left a regular seaward sloping floor. The very deep channels among the San Juan Islands, attain ing a maximum of ~04 fathoms (l ,!224 feet), are largely the product of preglacial stream erosion, and demand a deep Plio cene Strait Valley, as tJ1c Adru.iralty River dema11d5 a deep valley lo the ocean during the Puyallup interglacial epoch. INDEX. Pa(IIJ Aberdeen ••••..•..• , ...... • • . . . • . . . • • • . . . . • • • . . • • • • . . . . • • • • . • • . . . • . • 52 Admiralty OlnC!la.l Epoch ...... 1+-l.73 .Admiralty lnlct, dimensions of. .. . , ...... 106 AdmlraJ!:J Plaln ...•...... •....•...... •••.....•••...•.••.•..•• 200 Admiralty River •••...... •..• . .•.•.• ....•...... •••..•.••...... 204-212 Admlrlllty Sedlments ...... lli·l78 Admiralty TU! ...... l-l-173 Agns!Jlz, Louis . , . • . . • • . • . . . • • • . • • . . • • • . . . • . . • • . • • • • • • • • . . • . . • • . . . • . • 9i Alldel'tlon Iltlnnd ••..... , . . • • . • • • • . . • • ...... • • • • . • . • . . . . • . . . . • . 179 AnJma1 Remains 1n Admll'8lty Sediments ... •. .•.•.•••..••..••.. , . • . . . • . • 180 Arlington • . . . . • . . . . • . . • . . . . . • . . • . . . • • . • . . • . • • . . . . • . . • ...... • 167 Auburn DelCa •..•...••••.•..•...... ••.••....••...•...... ••..•..•...• 13,iX Ba.lubrldge lslaud . , .••...•...•....•..•..•.•• , • • . . • • • • • • • • • • • • • . • . . • • 214 Bald Bllls ••.•...••...... •••.•.....•.••.••.••...... •.•. 25·114 Bellingbrun ...... ••••...•..••.••••...... •...• .••••...... 77!229 Brg Lnke . . . • • ...... • • • . . . • . . . . . • . • . . • . . . • . • . . . . • • . . . • • • . • . . . . • • • 168 Black B1llil •••.••.••••••••..••••••.••..••••••••••.....•••.•.•.•. 17-80-200 Black Lnlce Outlet. .•.•.•...... •..••..•.•.••...•..•••.••...•••..••• 123 Blackwelder. Eliot . . . • . . . . . • . • • . • • ...... • . . • • • . • . • ...... • • . • 10 Blakeley Barbor . • . • • . . . • . . • . • . . • . . • ...... • • . . . . • . • . • . . • . • • • • • • • . . . • 215 Blue RIiis ...•.••...•.•.....•.•....•...•..•.•...... •.•.•.•...•....• 200 BotheU ...... 157·162 Bretz, J. R...... • . . . . • . . • ...... 12 Brlnnon Delta •••.• .•••.•.•. •• ...•••••.. •..•.•• .....•• ••.•••••.•• 1•6-222 Bucoda ...... 294:5·92-119 Camano Jlland ••.••••...•••••.•••••••..••.•....•...•••••...•..••• 184·186 Cal)ll lloru ...... • . • • ...... • • . . • • ...... • • . . • . . . • • . . • . . • • • . 220 C11sC1Lde Mountain glaclatlon • • . • • . . • • • . • • • • • • . • • • • . . • • . . . • ...... • • . 223 Cattle Point Moraine ..•.•.•...... •...••....•...•.••..•.••••...••.• 78·228 Cedar Creek (Black ams) ...... 30-40,58 ~ Ceder Rh'er . • • • . • . . • . • . • • . . . • • . . • ...... • • . . . . . • • • • • • . • • • • . . • • . • . . . • 223-1,; CedarvOle Prairie mounds...... 88 Centralia ...... •••...•..••..•..•.•.....••••..••••••.•...••.•• 45-50.120 )c. Chambers Creek •••••••••.•.....•••.••..•..••••.•.•.•••..••...• • ..•• 234 Chehalis (crty) ....•.••• •.•.. .••.••••.••.••••.••.•.••••• •.• .. ••• ...• 120 Chehalis (glJ1clA!) Lake ••.••....•.....•....•.•.....•...••..•...••.•.• 120 Chehalis glacial gravels, ecouomJc phases of...... • . • 57 Clear Lake (Bald Rllls) ...... • • . . . . 27 Clear Lake {Mclntollh) .....••.••••••..••••..•.....•...•••.•••. 28-46-65-118 Clltton Channel • • . . • . . • ...... • . • . • . • • . . • • • • . • ...... • • . . . • • • • • . . • . 14.6 Cloqua11um valley tralll...... • • . . . • . . • • • . . • . . . • • • • • • . • • • • • . • 50 Clover Creek CbJlnnel. . . • ...... • • . . . . • . • • • . . • . . . • • • . . • • • • • • • • • 128 Cot1Stttatlon, Mount • . . . • . • . . . . • • • • . • . . . • . . . . • . . . . . • . • • . . • • • • . . • • . . . . 80 Cord111eran glacier ot British Columbia•.•.•...•••.••..•.•..•...... •. ,17-88 Cosmopolle • . . • . • . . . . • ...... • • ...... • . . • • • • . . . • • • . • • • . . • . • . • • . . . 41 Cowlitz Valley ....•••.....••.....••...•.•.•.••....•••••••..•...••8842,58 Cy, Yount ...•.•..•..••....•.•..•..••.•.••..••.•... , , • • • • • . . • • • • • • . 224 Dabop Bay . • • • • • • • • . . • • . . . . • ...... • • . . . • . . . . • • . • • . . • . • . . . . • • . • . . . • 186 De.II, Wm. II.. • . • . . • . • • . . • . . • • • . . . • . . • • . . . • • . • • . . . . • . • • • • . • . . . • . . . • • . 180 Deeps ot Puget Sound •••.•••....•.•••••...... ••..•.•••.•.....••••• 216 Deltas lD the AdmtraJty Sediments •..... , ••••..•..•.•...•••...... •. 185 htdetc l'O!JIJ Denny um ...... l 7-t-17 1.Ju,i 'butc~ !tl\ll'r fall •.••.•••...••...•••.•.•••...... •..••...••..•. :!i'-117 Tle Molnus ... .. , ....•. , •• , ••••. , , .• •• , •..• , . , .....•.....•. , ••....•. l iO Dlnl!tropl1!Nm ot the J:'uget • ouna Hegton .....•.....•...... ••.•..••.. 21-:?:?6 D1nunlln-llke rld¢ng of tb.e VB.S.bon till .•...... •...... •...... !!011-2io.X Dnclrnl)u 11 \.,.l'lllcy .••.••.••.•• .• ..• • , . , . • ..•..••.•..•.•..•.•..•.•. J4 :?:?2 wwwnlllps Ynlley . , .....•....•....••.•..•...••.•.....•..•.•..• 3tl-H1!·2:!2 l!logl • IlllJ'bor ...•.••.•••. •.• •..• •• ••.•••••.••.••.••.• •. , • • • . • • • . • • . • 214 .llle.tonv!Il ...... •...... •...•.••.•...•.•...•.•...•.....• , .•..• 24-'.!u•il Blh • . . •• ••••. •. . • . . . . •• . .• . •...... • . • . . •. . • ...... • . • . 26 Elinor. :M unt ...... ail li!Wi(I ••••••.••.••••...•.•••••.••.•••••.• , .•••••••..•.• •.••..•• .•. .-10·50 E.r1>slon, glacl(ll, in troughs ot Puget 'ound. . . • • . . . • . • . • . . • . . . . • . . • • . • • . :!19 i...- 1:lverelt ...... • ...... • • . . . . • . . . . • • . • . . . • . . . . • . • . • • • . • . . • . • . 163 Ford tyr,e mounds. • • . • . . • • . • • • . . . • • . • . . • • • . • . • • . • • . . • . . . . • . . • . . • tl-9;;-10(1 b'oulwcntbcr Blull' ••.....•...... •.•..•.. , •. , ..•..•....•..•..•...... 1 l C,;n.te ...... ~· ·· · ···········"······· · ···· · · · ··· i.t7 Uato Pntbu·ny •. , ••...••.••..•....••.••..••....•.•..•...... :! -3 Poqe M~ 'ells lslll.lld .....•..•...... •...... , . . . . . • • ...... • • . l 2 Mlmo. Pro Irle •... , ...... ••...... ••...•...•...... •....•..•• 29- 9.L-93 < Mlma O'JlC mounds ...... , ..... , ...... •...... •... 2-9:i- Mlneral Lake 1,ap •. ..• ••. , •.•••..••. . • , •••..•••••••••• ,...... 58 Mock Cbl,tlloJJ -.nlley trnln...... • . • ...... • . . . . . 49 Mocllpe: ...... •...... •..•. , ...... •...... ••.. , .. , . . . . . • • • . . • 42 MoutcSll.llo . . . • ...... • • . . . • . . . . • ...... • ...... • . . . 132 Mulquceus •.....••....•...•...... •..••..•...... •...•..•••.•..••• 2i --HI Nabwa~el. Lake . . . . • ...... • • ...... • . . . • 32 'apavln divide •••..••. , .•. , . . . • • . . . . • . . • • • . . • . . • . • . • • . . • • • ...... fi9 Narrow!! ...•...... •...... •.....•.• ll.(l-14.2-l50-:.!b9 , e1vo.uku.m River col •.•••..••..•...•...••..••..••••••.•••.•••..••••. , 59 Newberry, J oll.11 •••••••.••• , ••••••••.•••.••••••••.•••.•• •• ••.•... ll-9 -106 Newcartle bUL ..•••.•....••...... •...•...••..•...••...•.. , .•....••... 101 Nl!!qunlly canyon •••...•••.••••...... •• •..•.• •••.....••.••... •. , , • , 2:'i-111 J,llsquAlly (glacial) Lake • . . • • • . . . . • . • . . . • . . • • . . • • . . • • . • ...... • . . • . . . . 141 Ntsquo.Jly Prairie ....•...... , •...... , ...... • , . . • . . • • . • • • • ...... 73 Oakland Bey .. , ....•...... ••...•..•••...... •.••••... , . . • . . . • 145 Oo.kv·IIJe ...... J0-4 2 Oakville PJ'.ll.l.rl~ mounds ....•. • ...... , •...... , .•.. , •.. , , • , , 88 Offn ts Ln.ke .•••..••••...•. • ...... •. •• .•...... •••.••• 66-90 Ohop Va1l~ ••.••••••••••••••••••.....•••..•...... • , .•••.• 24--72-1.27 £- Olympic . fountain glaclntlon .••••.. , .•••..••..•••..• , .•..•...... •..••. 221 rtlllg •...... ••.•.•.•.••..•...... •...•...... •..•...• 2+62-72...- 0sceola Glacler •••..••..••...... ••...... •.• ..• .. , . • . 28 - .Percival Creek • . • • . • • • ...... • . • ...... • ...... • . . . . • . . . • . • 123 .. l'b an om Lo.ke ••.•..••...••.•••.•...••...•...•... , ...... • Hi3 .Ph.V~logrophy. general, of the Puget ound Region ..... , ....•.•• , . • . • . • . . . I) Pllcbuc:k r k ...... , • ...... • . . 170 Pb1lchuck River •.....••...... ••...... •••.. , •..• , . . • • . • • • . . . . . l H3 Pliocene of tho Puget ound R.eglon .....•.....•...•...... •...•.. 18-200 .Po.rtH Creek ...•....•. , •... , ••...... •..•• , .•...••..••..•• , • . . . . 49 Po scs Ion Uead ...... •...... 17{ 'Poulsbo Cbann~l ..•. . , ...... • . . • . • . . • . . . • • . . • • . • • • . . . • . . Hfl Pte--AdmirDltl' tlll , ...... •...... • . , .••.. , , •.•...•...... 15·1 7 Preston . . . • • . • . • . • . . . . • ...... • . • . • . . . . • ...... • . . • ...... 151 Puget ound, V1m couver'e u ·og~ ot tbe Lerm, ...... ••.•. , ... , .•••.. , .• , O PuyuJJup. (glnchtJ J La.~ r...... 12fl &...- PuyullnJl LntcrglnclnJ ~IJOCh .• , . •....••••••.•.•..•....•• .•.•.• , •. , •.•• ll'i-1°2G QllllU/f Oeltn •...... ••..••.••. ..•.. •.••...... •...... 1 6-227 ullc.cne Riv r . . • . . • . . • . . . ..•.•...... •••..••.•••••.•..•••..... 14 Rn.lnler town) .•..•...... •...••••••..••...••...••...... •.....•...• 114-88 Rnlnler highway . , , , ... , ...•..• , ...•.•.•..•...•••.. , ..•...... , .. 71-72 Ren.!rnD. A.Ille rt ...... •.. , ...... ••.•...... •.. .••.. , .••• , • , . l ;c Red Orn,•els of the b bn!l Volley •.. , ..• , ...•..• , . . . • . . . • • ...... • . . 80 Redmond Deltll ...... •....•...... •..••...... , , .•••.... 153 Renton D ltn . . . • • . . . • . • • . . • . . . • • • ...... • ...... • . . . . • • • • . . 164 Richmond lleltn .•••..... ••...•...••.. ...•.• , •....••....•••...... • 139-232 Roekr Prairie mou.od ...... • ...... -00 oclry Prlllrle Page nm.ma.mlsb, Glactal Lake. •••.••.•••.•. , . . . • . . . . • • . . • • . . . • • . . . . • . • . . . . . 150 ~ Ju11.11 County m.orain-78, hlgb•level marine shells .• ..•••...•.•..••. 232 atsop ...... ••.••.•..••.••.••..• . , . . . . . • . . . • . • . . . . . • . . • • . . • . 40 atsop voJley train. . • . . . • . • . . • • . • • . • • . • • . • • . . • . • ...... • . . . . . 51 eattlle .. . •.••••••••.••... .•• •..•. •.•••••.•••••. •• .•.. l 14-166-178-1 1-231 Sequallchew DeJtn .•.••••••••..•.••.•••••.••.••..••..•.....•.•.••. 130-282 hell•bearlng till •.•..••.•...•....••.•...•.••••...... 70,230 belton Deltn ..••.•.•••.•.••.•••••.•.....••.•..•..••.•..••.•..•..• 75-143 'borloek De.ltn .•••••..• . .•.....• , • . . . • . . • . • • • • • . • • . • • . • • . . . • • • • . • • • 126 kokomlsh, (glaclnJ) Lake •••• ••••••••••• , •..••.•.....••.••.•..••.••.• 1411 $.kookum Chuck volley trllill ...•.••••..••••. , ..•..•..•.••...... •..... 2842 'lo_pe. or sutlace of tbe Puget Sound Gle.cle.r. • • • . • • . • • • • • • • • • • • • • • • • • . • 3\1. Smltb, G. Q ...... 12-23-140 Snobomtsb, (glaclnl) Lake ••.•. , •. , • . • . . . • . . • • . . • ...... • • . . 157 Snoqu11I mle .Flllls .. ...•..•.....•..•.•.•..•...... •... 159-224 noqulll.mfo Blver ...•.•••..•••.•.•••...••..•..•.•..• •.••.. 151-156-157-224 South Ellma •••••••• , • • . . • . • • • • • . • • . • • . • • . . • . • . • • . . . . . • . . . . • • . • . . . • . -10 ontb Prairie . . . . • • • . • . • • • • • . • • • . . . • • • • • . . . . . • . • . . • ...... 24 v South 'taeoma Cbllll.Del .•••.•.••.•..••.•.•••.•..••.•.••.. •..• .••..•.. 131 Spurgeon Creek glac1al dra.ina,ge cha.n.oel., . . . • ...... • ...... • ...... 1,0 quak Mountain •••.••••..•..••.••.•.••.••..•.••..••••.•..•...... , • 153 quallcu:m Delta .....•...•...•.•.•••..•.•..•.••..•...•...••....•...• 229 Squaltcum Moll1lt$1n...... •..•..•.••..•.•••...••••.•••....•..... 170-229 Steflacoom Delta . . . . • . . . . . • . . . • ...... • ..•...... 187-2,H s eUacoom l?le.:lns • . . • . . • ...... • . . . . . • ...... • • . . • . • • ...... • . . . . . 186 St1l11g11aml!lb River ...... •...... , •....•.....•...... •• 108-166 Stony Polnt ChD.llncl and valley train .....•...... •...... •.... 43-62-llO.-'{ Summit Lllke •..•.•...•...•...... •...... •.. , ...... •.••... 81-49 Tacoma •.•.••.•••••.•• ....•...... ••...... •.....•.. 220 Tacoma Delta (Admlr&.lty age) ..••.• ..•. •••..•...•..•..•..•.•..••••..• 1 7 'I'acoma, (gl11.clll1) Lake 11nd Delta ( Vas.hon 11ge) •••••..•.••.••.••.••.•.. 1.28 Tarr, Ralpb . ••.•...... •. • , . • ...... • . • • . . • . • . . • . . • • . . . . . 16 T nn111uat Prairie outwasb. . . • . . • • ...... • . • ...... • . . . . . • . . . . . 62 Tenino •...••...•...••..•..•.•..•..•.••...... •.•..•• 2 -29-46-65-02-J.03 Tenino-Grand Mound gl11.clal dralnage...... • . . • ...... 411 Upbam, Warl'Cll •••••.••.••••••••.••.••.•••.•....•..••••••••••.• 12-99-196 Vesbon gle.alal epoch ...... 17-221' Vas.hon gl11ci11tlon, age 01, .•...... •.... 1 , • • • . • . • . . . • . S6 asbon mora.lnes ...... •...... •...... 17-213 YD.llbon outwasb ...... •...... 17-36-01 allbon l:Ul, relation o!, to be troughs ot Puget ou nd ...... • . • • . . • 204 VegetaJ deposits In .Admiralty sedlments ...... •..•.....•••...... 170 Waddill.ls Creelc. •..•...... ••••....••.•••••.•.•.•....•....••..• 80-121 W·alr(cks Pl:'alrle • • . . . . • . . • . • . . . • . • • . . • . . • . . • . . . . • . . • • . . . . • . . • . . 8-ll0-103 W8Bhlngton, Lake ••••.•.•••..•.•.•.•.•..•.•..•...... • 135-151·156 Whatcom county moralnes-76, beaeb ridges ....•..•.....•..•...... •... 23S Whatcom, Gl&eial Lu.kc •.•.••.•..••.•.•...... •.....•.... •• ...... , . . . • 170 Wb.ldbey !Bland ..•..•••••..•.•.••••...•••..•.•.••.•...... 183-202 Whites .M11L , •• , , , •• , , , , •••••. ; , ••• , , •• , ••• , , • , •• ••• .• • , • , ••• , • • • • • 4.0 Wlckerl!.ham •..••...... •..•.... , ...... • . . 171 Wildcat Creek •...... 40-~9-51 Wilkes, f:harles .••.•...••••.••.••.•.•••.•..•.•.•••.••.•..•..•....•. 10·96 WillLB, l\auey ...•.•.••..•.••.• 12-14.-16-28-61-133-184-140-171'i·l 78-187-189-197 Wing 'Po1nt • . . • . • • . . . . • • . . • • . • . . • . • • . • ...... • • . . . . • • . • . . • . . • . . . . . 220 Wlsbkah Valley •• , • • . . • • . • . . . • . • . . . . • • . • . . . • . . . . . • . . • • . • . • • • ...... • il Wynoocbe VeUey • • . . • • . . • ...... • • . . . . • . . . . . • . . . . • ...... • ...... • ~l Yelm Prairie ••••..•..•.•••.•..•••..••.••.••.•••••••.•••.•.••..•... 68·73 I ) 7 p T OF THE W HINT GEL I AL RVEY. Volume 1.-Annual Report for 1901. Part 1, Creation of the State Geological Survey, and An utline of th Geology of WasWngton, by Henry Landes: tlart 2, The Metalliferous Resources of Washington, IDx oept Iron. bY Henry La-ndes, WHllao, S. Thyng, D. A. Lyoo. and. Milnor Roberts; part 3, The on-M ta.llilerous Resources oC Washington, Ex cept Coal, by Henry Landes: part 4, The ll'OD Ores of Was.hlngtOll, by S. Shedd, and the Coal D poslt of Wasblngton, by Henry Le.ndes; part 5, The Water Resources of Wasblugton, by R . G. Byers, C. A.. Ruddy and R. E. Heine; part 6, BibUo_graohy of the Literature Reterrtng to the Geology of Washington, by RaT}lh Arno1d. Out of print. Volume 2.-Annual R port for 1902. Part j, The Building and Or namental tones of Washington, by S. Shedd; part 2, The Coal De poslti, or Washington, bY Henry Landes and C. A. Ruddy. Postage 20 cents. Address, State Librarian, Qlyn1pla, Washington. Bulletin 1.-Geology and Ore Deposits or Republic Mining DI.strict, by Joseph B. Umpleby. Bound in cloth; price, 35 cents. Address, State Librarian, Olympia, Washlngtoii. Bulletln 2.-The Road Materials ot Washington, by Henry Landes. Bound in cloth; price, 60 cents. Address, State Librarian, Olympia, Washington. Bulletin 3,-Tbe Coal Fields of King County, by Geo. W. Evans. Bound in cloth; price, 75 cents. Address State Ltbrarla.n, Olympia, Washington. Bulletln 4.-The ement Materials ot Washington, by S. Shedd a.nd A. A. Hammer. 1n preparation. Bulletin 6.-Geology and Ore Deposits of the Myers Creek and Oro ville-Nlghlha.wk Districts, by Joseph B. Umpleby. Bound in cloth: prlce, 50 cents. Address, State Librarian, Olympia., Washington. Bulletin 6.-Geology and Ore Deposits of the Blewett Ml.nlDg Dis· trlct, by Charles E. Weaver. Bound in c.loUJ: IJrfoe, 50 cents. Address, State Librarian, Olympia, Washington. Bulletin 7.-Geology and Ore Deposits of- the Index J\UnJng District. by Charles El. Weaver. Bound in cloth; price, 50 cents. Address. State Librarian, Olympia, Washington. Bulletin 8.-Glaoiation of the Puget Sound Region, by J. Harlen Bretz. Bo!Uld Ln c1oth; prlc , 60 cents. Paper cover: price, 35 cents. Address, State Ltbrartan, Olympia, Washington. Bulletin 9.-The Coal Fields or Klttitas County, by E. J. Saunders. In prel)aration. Bulletin 10,-The Coal Fields of Pierce County, by Joseph Daniels. In .Drepara.Uon. Bulletin 11.-The l\tineral Resourcei; or Washington, with sQl.tistlcs for 1912. by Henry Landes. 1n preparation. Bulletin 12.-'Blbllograpby o! Washington Geology and Geography, by Gretchen O'DouneJl. Paper cover; price, 26 cents. Address, State Librarian, Olym_pfa. Washington. Bulletln ta.- Preliminary Report on the Tertiary Formations of Western Washington, by Charles E. Weaver. lu preparation. Bulletin 1 .-The Qulnc · Vu.lley lrrlgutl u Project, b; H .nrr Land s, A. W. Maugurn, R. K. naou, .... J. auuder , aud Jo·et)b .fac bs. Bound In r,aper; price, 20 c n1 . ddr ss, State Librarian. l)'rupla. W 11blngtou. Bulletln 15.-A Preliminary R 11 rt on tbe Tertiary Pal ntology or , eswrn Washington, by Cbna. Ill. W a\· r. Bou.o.d in paJ)er; 1irlce, 20 cents. Address, State Llbrarl n, IYlll{lla, Washlugton. Bulletln 16.-Geology and Or D J)OSlt.s of tbe Covada l\llntng Dls- trl t, bY ho.rles ID. en.v r. Pan •r cov r; price. 25 ents. Address, State l,lbmrlan, OlYII1pia Washington. PUDLI ATIO, S OF THE . . GEOLOGICAL Ol\""EY, L'I O· OPEllATIO • , ITH THE WA lID OTO.' GEOLOGICAL SURVEY. {For co1>les of these publlcatlon ddress the Director, U. s. Oeologl· cal Survey, Washington, D. C.) Touograph1c Maps of the Followlog Quadrangles: 1.ount Vernon, Quincy. Wlncbester, .Moses Luke, Beverly u.nd Red Rock, Cedar Lnke, Pl'lue, 10 ceJJts each. Water Supply Paper No. 263: Water Powers of the Casoad Range, PnrL I, outhern WashlngtoJJ. \ at r upply Paper No. 313: Water Powers of the Cascade Range, Part 11. Cow!U~. ·1sqWl.l!y, Puyullnp, White, Green, and Cedar Dralu· age aslns. Wat r Ut>PIY Paper . ·o.... ~ ~ t r P w rs of the Cascade Range, Parl DI. ln preparation. Wat r upply Paper No. :ni: Surra e Water Supply or tll United Stat s, t. 09. Plll"t Xll, North PacU\c Co11s \ al r Supply- Paper o. 292: urta e Wat.er Supply ot the l alt d St.at a, 1010, Part XII, North acme Coa.sL. Wnter Suvply Paper No. B12, 19J L. Io preparallo.n. W t r Supply Paper No. 332, 1912. ID nr paratlon. PU LI ATIO. S 07 THE . S. DEPARTME1 'T OF AGRICI LT Rm, BeREA OF SOILS, [. ' -OPER TIO.' WITH THE WA..SH1NGTO E LOGICAL VEY. (For co1,I s of the e publlcatlou11 addr ss on of th meml1 •r or congr ss rrom Washington.) R connoless.uce Soll Sun· y or lh Easteru Part of the Puget Sound Ba.sin. Reconnolssnnce Soll Surv y r th stern and Southern Parts of tll Pug uod Basin. Reconnolssa.nce Soil Survey or ou h st rn Wasblugtou. R onnols ance son S11rvey or tb Quincy Area.. WASHINGTON GEOLOGICAL SURVEY BULLE1IN NO.8 PLATE XXII I •Prairie C' , ...•.•. .... o -, .. , V ;:--...... - u 7' -:---.,. ft .... 4. ,-:::-_ _ .A , . 8 ---. -~-1J C}.. 01' ----.-}; Y JUAI! D ... <:> '1>' ~, & \ PLEISTOCENE SURFACE DEPOSITS ~~ OF ~~ PUGET SOU~D BASIN ) SCALE: 1 Iocb =6 ~tiles / / I , / o Outw.. " G,avels / I f:''':'''; I O,I,nlll:' C"annel, 'po ./ o Alluyiu m Ind Mlrine Oeposin \, b 11 D Drift·bea,ini Rock Hm, t-\, o Orlftle .. Ate .. ~•• •• __ , •. 1Oe lt .. ~ ..!..!.e...... ,t U Unsurveyed Are .. f1 \ I -~--,·---·--·- ... --- .' ..... '. ,/: • HtUhu.I'eb . OLYMPIA"." " .. "", I--~-.-- .------.---:<"~-04 FO REST RESERVE ...... ~. co, .....,,~. WASHINGTON GEOLOGICAL SURVEY BULLETIN No. 8 PLATE XX1l1 ----·-·OUTWASH------·-·-·--·-·-·---- MORAINE AND SOUTH OF PUGE··~ T SOUND ---·,----I erm111al &lid Recessional umora' ines i 1-T.2 [I1J] Ground Moraine 3 tS;;:j Maximums outh effl Ektent of the Vu ..'- on Glacier 4~ Outwash of the E,to,ern .. lobe ~ 5 IL: ~o·rj 6--*-1 Mound Praule S IJ>~o}:oJ>I Mock Chehalt$ Valley Train Higher Terraces of the Mock Ch ehalis Valley Train 7 ~~·=·:·= ... ·.·. Cloquahum Valley Tn,in 8[[]t.. • ·.I.. • • . oW}JJ 51.tsop Valley Train. lowest Terraces 10 '& Satsop Valley T1ain' Mlddl e Terracas 11 - Satsop Valley Train• High est Tarr.111te s Gl&ciaf Orain14re Channels 121:::~ •,::.?.•J •s&ll Like Ch.,halls Area •nd the N',squ.a Ily Bottoms I~~ Rock Hills with ttlln or scattered Drift 150 Driltleu Areas • NapCl.nne Scale. 1 inc_h-- 3 mi.es., WASHINGTON GEOLOGICAL SURVEY BULLETIN NO. 8 PLATE XXIV FUG'j! ~ 2:) ~ 0 \:C..... ~ i::, .... 0) ~ \:1 ~ ~ ,-6 ~- ...:I< 000 z.... /l.. "" Breidobl ich. 0z 0 !'-, 0...:i ~ TACOMA BATHYMETRIC MAP PUGET OFSOUND NOTE: BATHYMETRICINTERVAL=20 FATHOMS SC.ALE: l lnch-2.50 MU M OLYMPIA