JEFFERSON COUNT¥ ENVIRONMENTAL GEOLOGY STUDY Geologist (125 days@ $125/day) • $ 15,600 * Editing (65 days@ $77/day) • 5,000 * Cartography. 4,000 * Supplies. • 750 * Printing. • 4,900 Travel and per diem Per diem - $27.50 x 60 days •••••••••• • $1,650 Travel to job - 566 (mi. round trip) x 12 x 14¢. 948 Travel on job - 100 x 60 x 14¢ • • •••• 840 3,438 * Overhead on* items above - $28,788 x 20%. 5,757 TOTAL. • • • $ 39,445 Maps: (1) Geology - 4 or 5 color (1 inch= 3 miles) (2) Mineral deposits (combine with geology?) (3) Urban - 7~' - 1:24,000 (black and white) Bulletin Start August 1 if no ERDA uranit.nn study Start March 1, 1978, if ERDA uranium study Contract for flat fee - 60% from county •••••••••••••• $ 24,000 )< Gs-C!J~C-/j' ~ )( -· /-J t:Cl rT,; >-J c; .,, /~ 6DO ;,, Cdjvz To_; 5;0CJO ;Jl(d-, p F J' cL..,.-'.=. 5 ~ (;Yoo -:? / rtZ,, ✓ J /; ✓ (-; -7so y/- ) <",,,..., •..f10 -0, 4 / 9 CJO 77.o, v _, /-O,.tz: T ;,s ... ~ /.J; L:>Vt 7e.,, u 7o JD";, z 8 3 fl? ,. ,. 2- x: / z. ,c /~ ~ , ' Q ,,,-1 ;;;;-~ / ,,...,,c"? )('. 5 y / 2- )C / ,3. ~ /L~/-'.,'/~5 /4 G'~?--8~·-r - 4 -c,-r 5°' Cr?n-c;;,.>c - ~"'--,s ;' /./'I.,.,,, ✓ ~ "'1L /JJSPc,s,-,s Cc ~&-rs/--. i-v~ ,,'-( qco <- oc,-r- •;,; LJ «: ~,e,o,/ - 7£/ / - - ✓, ~,.G ~ t' )OO -/3Ch/ . • . C),,..J t:,..._,?. ~s "7? .)(/ -0.,...-e:. ~~r. T>m1,~ --<--. ~$r ', 1 ,·? J y ~ /tf. tr--0 ro.. A Jz.&.o If/. IJO '1.i,,,,{ • /tJ.oo /'J.-6-C)O 3, Cf I 00 tJ(tt':ll' 5! 00 ,, .:2,..S~ .56',oo ·' .5t' ro ')..&,/, 00 ,, ~)-1, (co ,. t, 3, §o ~fµ,. qt),/t, D~ 3 I, IO /tJJ& . 4fto3 tJtu« 75;, 33 If 79. So f>a<h,,v-­ 73,oo / (t) 7, / 0 .J.)/IA-;r:-- ;5J,oo 1 o/, fc,O cJ.J!clevJ /2t. oo f1, 3S- l/t76.77 4.-¥ ~/:.. It~ 31/ f1<!:V ~bu-~ 612.00 /o;;.3,oo /.t/lo/,00 58'3,£'0 .. J ' i) '),, 5'(/) Z. o O D · s-e ~jl~ J uoz . .fo ca ✓,;R) G~- ~ ~ ~ 6~ _,__ &~ ~ ~ ~ ni~ ~ ~~ Y'-'<-~-- ;11/J-~- (t L~ z~._$:_ ~ rep~~-<,I / / Nttn-'JnZT~ c-,.,.£u- ·" ~\ ~~ . ' /~~- ESTil-tATED SCHEDULE OF COSTS A. Field mapping and inventory of existing operations (6 weeks) $3,700 B. Field analysis (3 ueeks )1 1,800 1 .. compilation of base map data 2o minera~ resource revie,~ C. Report uri ting and editing (5 weeks) g g O (j D. Co.rtoCTI"aphic drafti~g 2-, c: 0 E. Typing and correcti~g final manuscript (4 ,meks) 700. F. Transportation and incidental expenses G. Map supplies and equipment --500 TOTAL ESTIMATED COST $13,500 Quaternary glaciation and volcanism, Metolius River area, Oregon WILLIAM E. SCOTT'· Department of Geological Sciences, University of Washington, Seattle, Washington 98195 ABSTRACT INTRODUCTION ington, Cali fornia, and the Rocky Mountain states, few detailed studies of Evidence of three major Quaternary During Quaternary time, the Cascade glaciation in the Oregon Cascades have glaciations is recognized in the Metolius Range of Oregon was repeatedly subjected been published. River area on the east flank of the High to both valley and ice-cap glaciation. The The present study involved the geologic Cascades. T he latest glaciation (Cabot effects of glacial processes in modifying the mapping of surficial deposits along the crest Creek glaciation) is multiple, with evidence original volcanic topography are well dis­ and eastern flank of the High Cascade of a late readvance (Canyon Creek ad­ played by deep U-shaped va ll eys, numerous Range in north-central Oregon near three vance) well displayed in cirques. Post­ cirques, well -developed end moraines, and large Quaternary stratovolcanoes, Mount Altichermal glacial activity is restricted to a deeply eroded stratovolcanoes. However, Jefferson, Three-Fingered Jack, and Mount twofold lace Neoglacial advance on Mount compared with well-studied areas in Wash- Washington (F ig. 1 ). This report describes Jefferson and Three-Fingered Jack. Scone­ weathering characteristics and soi l devel­ opment are used to differentiate and corre­ late the drifts throughout the area. The de­ gree of soil development on the drifts suggests that there was a longer period of time between the oldest and intermediate glaciations than between the intermediate and youngest glaciations. Volcanic activity may have been re­ stricted to times of little ice cover, since no evidence of intraglacial volcanism was ob­ served. Tephra and lava flows were erupted during two Pleistocene interglaciations and during Holocene time at scattered loca­ tions. The High Cascade platform and probably the scratovolcanoes were largely cons!ructed prior to the earliest recognized glaciation (Ab bott Butte glaciation). In formation on extent of ice cover during the Cabot Creek glaciation and the Neogla­ cial advance is sufficiently detailed to re­ construct past glacier margins and estimate former eq uilibrium-line altitudes (ELA). An accumulation-area ratio of 0.6 ± 0.1 was employed to calculate past ELAs. During the Cabot Creek glaciation, ELAs ranged from about 950 m lower than present at the maximum to 700 to 750 m lower than present for the Canyon Creek advance. Neoglacial ELAs on Mount Jefferson glaciers were lower than present by 200 to 250 m. ELA gradients across the Western Cascades during the Cabot Creek glaciation averaged about 5 m/km, increased to 14 m/km across the High Cascades, and were greater than 38 m/km farther east. This re­ 0 10 20 30 flects a pattern of precipitation similar to km that of the present. • Present address: U.S. Geological Survey, Federal Center, Denver, Colorado 80225. Figure 1. Location of study area. Geological Sociery of America Bulletin, v. 88, p. 11 3-124, 12 figs., January 1977, Doc. no. 70113. 113 114 W. E. SCOTT the stratigraphy of Quaternary glacial and TABLE 1. CRITERIA USED TO DIFFERENTIATE AND CORRELATE DRIFTS volcanic deposits, the extent of former glaciers, and estimated equilibrium-line al­ Criterion Application References titudes (ELA) of present and former glaciers. Discordance in Well displayed in some valleys with moraines Sharp and Birman (1963) moraine t'rends of both Cabot Creek and Jack Creek age Previous Work Morainal Made subjective judgment of crestal sharp­ White (1962), Rampton (1971) morphology ness. Proximal and distal moraine slope From their early reconnaissance studies, angles measured by inclinometer Dutton (1889, p. 161) and Russell (1905, p. Weathering characteristics of stones 30) realized that the entire summit platform Surface- Counted number of boulders in 3 m X 30 m Blackwelder (1931), Sharp of the High Cascades had been covered boulder area on moraine crests. Of limited use due (1969) with an ice cap and that outlet glaciers had frequency to variable tephra cover descended the eastern and western slopes Stone-weather- Collected 40 to 186 cobbles and pebbles from Blackwelder ( 1931), Birman and constructed conspicuous end moraines. ing ratios surface to 30-cm depth at sites on moraine (1964), Sharp (1969), Carver Multiple Pleistocene glaciation was first crests and high points on ground moraine. (1972) suggested by Hodge (1925, p. 38-40). Used ratio of unweathered:partly weath­ ered (rinds, pitting, interior staining, but From studies in the valley of the North San­ cores still fresh) :totally weathered (no tiam River west of Mount Jefferson, Thayer fresh cores, easily pulverized) (1939) presented firm evidence for a Crandell and Miller (1974 ), threefold glacial sequence that he correlated Thickness of Used pebbles and cobbles from surface to weathering 30-cm depth at sites where stone-weather­ Porter (1975a) with the Sherwin, Tahoe, and Tioga drifts rinds ing data collected. Measured rind thickness of the Sierra Nevada. Crandell (1965) to nearest 0.1 mm under magnification on summarized glacial-geologic studies in the 15 to 30 stones with best developed rinds Pacific Northwest and delineated the extent Degree of soil development of ice in the Oregon Cascades during the Profile Profiles were described from similar settings See discussion and references in last glaciation. His map shows a continuous development on moraine crests and high points on Birkeland (1974) ice cap extending from 30 km north of ground moraine; all soils are developed in Mount Jefferson to Mount Mcloughlin in till from andesitic source rocks. Noted southern Oregon, a distance of almost 300 horizon thickness, color, consistence, km; a small ice cap around Mount Hood; texture, structure, and boundaries and small valley and cirque glaciers near the Free iron oxide Used Jackson's (1969) citrate-bicarbonare­ Ugolini and Bull (1965), Mountain Lakes Wild Area and in the oxide and dithionite extraction and measured Fe on Jackson (1969, p. 44, 49- Western Cascades. Most recently, Carver hydroxide atomic absorption spectrophotometer. 51 ), Alexander (1974) (1972) completed a study of Cascade glaci­ content Determinations made on samples from ation south of Crater Lake and in the each horizon or at 20-cm intervals vicinity of the Mountain Lakes Wild Area. Using weathering characteristics of the TABLE 2. UNITS RECOGNIZED IN THE METOLIUS RIVER AREA drifts, he differentiated six Pleistocene drifts, a Neoglacial drift, and a variety of Geologic Glacial-stratigraphic units Rock-stratigraphic units Pleistocene and Holocene periglacial de­ time units posits. ..c u Till facies 0 Geologic Setting of the w0.. Jefferson Park Jefferson Park Outwash facies ., Holocene advance } formation Rock-glacier deposits High Cascades c:: } 1:l interglaciation } Protalus deposits 0 Forked Burte } Forked Burte formation Apparently the volcanic acnv1ty that 0 nonglacial interval formed the Oregon Cascade Range was :r: episodic. McBirney and others (1974) con­ Till facies cluded that four relatively short eruptive Canyon Creek Canyon Creek Outwash facies intervals occurred during Miocene, Late advance member Miocene-Early Pliocene, Pliocene, and Cabot Creek } Rock-glacier deposits Quaternary time.