Fraser River Tertiary Drainage-History Placer-Gold Deposits

Home , McGregor River, Monkman Pass, Nechako River, West Road River

BRITISH COLUMBIA DEPARTMENT OF MINES Hon. W.J. ASSELSTINE, Minister JOHN F. WALKER, Deputy Minister

BULLETIN No. 11

Fraser River Tertiary Drainage-history in relation to Placer-gold Deposits (PART 11.)

DOUGLAS LAY

1941

VICTORIA, B.C.: Photooffset by CHARLES F. BANFIELD. Prinkr to the King's Most Excellent Majeay. 1941. CONTBNTS

Page

INTRODUCTION . 1

SmmY 3

TOPOGRAPEY 7 Fraser River Valley 7 MeGregor River 12 Neohako River 14

. ILLUSTiiATIONS

Facingpage

Plate I A. Pinnaclein Tertiary gravel of the inter-volcan-ic Fraser River at the BigBend, 10 miles north of Quesnel...... 46

B. Differential weathering in intra-Upper Volcanics - sedimentslying between

lavabeds, near Macalister...... 46

Plate I1 A. Drag-linedredge of the North American Goldfields Ltd., Praser River 1 1/2 milesup-stream from AlexandriaFerry...... 50

B. Placeroperation of H. Craig,Fraser River 2 milessouth of Quesnel 50

Keymap showing locationof Figures 1, 2 and 3...... 9

Fig. 1. ?lan of FraserRiver extending from WilliamsQuesnel. Lake to 21

Fig. 2. Plan of FraserRiver extending from Quesnel to Summit Lake ...... 23

Fig. 3. Tlan of FraserRiver extending from Prince George to Monkman Pass...... 31

Fig. 4. Plan of Nechako RiverDelta 37

Fig. 5. Plan ofTertiary the Mine. 49 FRASZR RIVZRTlRTIARY DRAINAGZ HISTORY

IN RZLATION .TO

.PLACZR-GOLI) DZTOSITS

(Part11)

1NTROI)VCTION

This report supplements 3ritish Columbia jjepartmentof nines Bulletin No. 3, 194.0, and continues the investigation the of Fraser River drainage as far as the Grand Canyon, 109 miles up-stream from Frince George. The river, confinedfor 120 miles up-stream from this point, emerges from the Rocky MountainTrenc'h through a wide local breakin the north-westerly continuity thht of great valley.

Reference is invited to British Columbia Departmentof' Mines Bulletin No. 3, 1940, for much preliminary information whioh is not repeated in this report.

For convenience the terms usedto desipate' the Fraser River at different periodsin its history, givenon page 2 of Bul.letin No. 3, 1943, are repeated here. The terms "pre" and "inter" are used ip the ordinary geologic sense. The term "pre-volcanic Fraselr' River" designates tne river antedating the volcanismex- presssd by the Lower Lavas. The term "inter-volcanic Fraser River" is applied to the river flowing between the two periods of volcanism expessed respectively by the Lower Lavas and the Upper Volcanics. The term "intra-Lower Lavas Fraser River" is applied .to the river flowing during or before actual cessat.ion of volcanism expressedby the Lower Lavas. The term "intra-Lipper Voloanics Fraseriiiver" is applied to the river flowing duringor before actual cessationof the volcanism expressed by theCpper Volcanics. Zxposures of sediments of the last-mentioned were found during the field work of 1940.

To facilitate examinationof all rock-outcrops on both banks of the Fraser River, investiration during 1943 was made by outboard-enginad motor-boat, between Macalister and the Grand Can- yon. The XcGregor iiiver and Herrick Creek were ascended as far as the junction of Fontoniko Creek with the latter.'&ere deemed necessary mountains adjacent to the river were examined, and after completion of reconnaissance by boat, regions more remote from the Fraser River adjacent to its large tributary, the Nechako River, were explored.

Although this report does not deal with the Pleistocene drainage-history of the Fraser River, it was found necessary to devote some time to study of Pleistocene features to decipher Tertiary drainage-history.

-1- Nostelevations mentioned were determined. by altimeter, the instrumentbeing checked as frequently as practicable bycomparison withGeodetic Survey monuments atPrince George,Stratnnaver and 2uesnel. .In some casesthe context renders clear that elevations givenare those determined by the Department of Lands.

It is desired to tenderthanks to C. C. K.ellyof the British ColumbiaDepartment of Agriculture,in charge of thesoil survey of a largearea centerinc in ?rinceGeorga, for kindassistance extended in various ways.

Thanks are also due 3. IIobe and X. Framstatfor timely and invaluable assistance in navigating the difficult waters of Herrick Creek.

Assistance in the field was renderedby Alan R. Smith and Lorne 2. Rowebottom.

-2- A summary of the more important facts ascertained in the course of field work during1940 is g.ivenbelow. Detailsfollow in the body of thereport. . ..

(1) On theeast bank of theFraser River, somewhat over 3 miles north of Shelley,exposures of sediments(conglomerate.and sandstone) of thepre-volcanic Fraser River, occur in the Canadian NationalRailway-cutting and .extend below river-level. Eo fossils werefound inthese sodiments and the state of preservation of silicifieddriftwood proved.too poor for identification. The hi&h degree of lithification of thesediments suggests that their age is early Zocene or possiblyeven iate Cretaceous. This exposure is deemed of high critical value as it proves not.. only . the far northern early deep incision accomplished by the pre-volcenic Fraser River, but also the exact position of the river at tnat t ime .

(2) This examinationdisclosed a wide brea!c inthe Rocky MountainTrench near the Grand Canyon. At thispoint the southern wall of the Trenchends abrupt1y;while thenorthern wall coztinues but a fewmiles farther to terminate near Sinclair Mills at the great gap about 12 mileswide, caused by thejunction of the McGregcr RiverValley with theFraser River Valley. This break in the continuity of the Rocky XountainTrench continues until it is restor.ed to norm1 proportions at the junction af the valleys of the Paclc.andFarsnip Rivers, from when-ce it continues north.- westerly for many miles.After flowing confined within the Rocky MountainTrench for 120miles, the.Fraser RivSr emerges from it . .just above the Grand Canyon; and then'flows over the eastern edge of the Nechalco Plateau.. The river makes a bend at its most northerlypoint by reason of thesurrounding structural features. The Arctic-Pacific Divide, but a few miles west of the McGregor River Valley, trends directly across the direction of flow of the river up to this point, and it is apparent that at no time in its history canthe Fraser River have continued to flow in a north-westerly directionpast the mouth of the KcGregor River. It is, hoxever, quite possible that there hasbeen a reversal of-flow of t:he waters in that part of the Fraser River down-streamfrom the mouth of theMcGregor.River, as sugEestedin (4) below.

(3) . In thecourse of thisexamination, an intrusive .tongue of diorite was discovered at the north-western endof thejearpaw Mountains,,north-east of Sinclair Mills (Fii.3). This' range of mountainshe.re forms the northern wall of the Rocky ?lounta.in Trench,the north-we'sterly continui,ty of which is at this point interrupted by a .wide breakas rnentioned in (2.) above. The occur- rence of intrusive rocks in the northern wall.of. the Rocky Mountain Trench ani north of Eaglet Lake indicatesthe far eastward extent of theeffects of theJura-Cretaceous revolution. The presence of intrusiverocks at thesepoints, also suggests the likelihood that the Rocky MountainTrench and some parallel trenches in this region weredeveloped prior to the Laramide revolution and gradual uplift of the Rocky Mountains.Pronounced trellis-typedrainage is ex- hibitedlocally to the south-east of the McGregor River(Fig. 3).

(4) The evidenceobtained suggests that drainage in thesouth- westerly flowing parts of Berrick Creek and'the McGregor Riverhas beenreversed (these waters are virtually oneand the same stream occupyingthe same valley, and are referred to in this report as the "SerricL"McGregor" River). In lateCre-taceous time; possibly extending to early Tertiary time, these waters were likely the headwaters of the Murray River,then flowing north-easterly throughthe site of theMonhan Pass in the Rocky Mountains.Quite possiblythe r'raser River at the great bend at its most northerly pointnowoccupies the deepened bed of a former tributary of the Herrick-McGregor River,then flowing in the opposite direction. Reversal of drainage was due to two causes:(a) Cap-ture of its headwaters by the ra~idly-rejuvanating southerly-flowing Fraser River(evidence cited in (1) above), nlhich sappedthe power o'f the IIerrick-McGregorRiver tomaintain its flow,as did the Peace River,against (b) the slowupheaval of the Roclcy Kountainsduring the Laramide revolution in early Tertiary time.

(5) Supported by strongalthough indirect evidence, it is postulatedthat in late Cretaceous time the ancestral Fraser Riverdrainage was northerly.ðer this drainage was mainly by thePeace River and partly by the Herrick-McGregorRiver, or partly by thePeace Ziver and mainly by the Berrick-McGregor is conjectural, but the result of this examination favours the adoption of the latter hypothesis.

(6) Reference(Fie. 2) will renderclear, that the Fraser River makes a wide detour to the west between %kites Landing and tie mouth of theCottonwood.River. Exposures leave no doubt as tothe reason. The pre-volcanicsoutherly-flowing Fraser River, intra-LowerLavas Fraser River and the inter-volcanic Fraser River, occupied a valley trendingalmost duesouth between T,Pnites Lading and the mouth of the Cottonwood River,the approximate position of which is indicated(Fip.. 1 British ColumbiaDepartment ofMines Bulletin Eo. 3, 1940). Thisvalley is now largelyfilled except at its north-westernextremity where it is occupiedby the northerly-flowingpart of Canyon Creek. The westernrock-rim of tiis valley is therocky region west of WhiteslandingCreek, and theeastern rock-rim is exposed on Government,Hixon, Terry and Ahbau Creeks,and on the Cottonwood River at the highway crossing. Prior to theinter-volcanic Fraser River, the waters occupied the easternpart of this valley. From exposures of Australian members (a) of theFraser River formation, and' ofsediments of thepre- volcanicsoutherly-flowing Fraser River on Canyon Creek, it is believedthat the accumulation ofsediments in the eastern part of thevalley caused the inter-volcanic Fraser River to shift to thewestern part of thisvalley. 2xposures also demonstrate conclusively that up to this timethe WestRoad (Blackwater)River joinedthe Fraser River at h'hites.LandinE, and that that part of the present Fraser Ri-ver Valleybetween the mouth of the West Road River and the mouth of the Cottonwood River was not than in existence. \,;hen theFraser River was subsequently dammed at down- s-tream points by the .Upper Volcanics, it abandoned its ancient valley in this region which was .largely filled with an imme:nse accumulation of sediments. A new valley was incised between the former mouth of theKest Road River(half a mile above the ?resent mouth of this river) and the mouth of the Cottonwood River, and drainage was reversedin the former nort'n of its mouth. The Cot- tonwood Canyon is largely a post-glacial and Pleistocenefe;%ture, but the Tertiary Mine-Canyon Mine channelquite possibly re?re- sents the Tertiary cutting of thelower end of thedetour.

(7) No evidence was foundof damming of theFraser 9iver by either Lower Lavasor iipper Volcanics sp-stream from Quesne:t. On the ot'nerhand there is veryconclusive evidence of the damming of the ilechakoXiver and its tributary,the Chilako River, by the Lower Lavas. If theselast two rivers were dammed by the Upper Volcanics no evidence of it was found.

(8) During 1943, largeexposures ofsediments of the Fraser River damqed by the Upper Volcanics werefound (to which theterm "intra-UpperVolcanics Fraser River'! is applied),near the top of the east rim of the Fraser River Valley near Macalister.

(3)Lacustrine deposits, believed to be of Tertiaryage, were discovered at severalpoints: west of theFraser River near PrinceGeorge; on bothbanks of theFraser River near the Junc- tion of Tabor Creek, and on Government,Hixon and TerryCreeks. These depositsfor= a false bed-rock on which, inseveral instances, imi)ortantconcentrations of placer-gold are found.

(10) Comnercial Possibilities

(a) T'ne cssociation of a concentration of placer-.gold- with thelacustrine deposit on theeast si2e of theFraser F:iver near Tabor Creek,indicates the advisability of prospecting on thewest side of the river in -this region where' a similardeposit exists.Unless post-glacial pavels directly overlie the 1a.tter Ynerecanno-t, of course,be any placer concentration due to the excellentfalse bed-roc:: formedby thelacustrine deposit. This furthercondition must therefore.besought. Prospecting a1E.o seems merited on the east side of the river north andsouth of t'ne points at which the lacustrine deposit is exposed.

-5- .It is a rational inference that there mustbe a concentration of placer-gold in the bed OS the river %here it cuts the deposit,but in viewof thedepth and velocity of the river, it seems unlikely that the gold.can be profitably recovered..

(b) The exposures ofcompacted sediments of theTer- tiary '/Jest Road River,and. of the well-lithified sediments of the pre-volcanicFraser River near Sh.elley, described in detail in the body ofthis report, are in both cases of considerableextent. The questionarises as to whethercommercial possibilities exist in eithercase. Recovery of bed-rockvalue's could only be made by deep-leadmining methods, the cost of whicheven although no dif- ficulties wereencountered due towater or badground, would be unavoidablyhigh. Unfortunately, moreover, important critical factors are entirely unknown, for example thedepth to bed-rock, and t'ne bed-rockvalves. In both^ casesbed-rock is below thelevel of theFraser River. The valuesfound in the Tertiary Mine (see Bulletin No. 3, 1940) mightserve as anindication of what may be expectedin the case of tieTertiary Kest Road River. In thecase of theexposures of thesediments of the pre-volcanic Fraser River, nearShelley, it is even mor~a difficult to form an opinionof bed- rockvalues. In thiscase all that canbe said is thatthe river possibly eroded a quartz vein terrain up-strea- at its mostnorth- erlypoint. The presentoutcrops of theseveins ar- only slightly aurifer0u.s.

-6- TOPOGRAPHY

Fraser River Valley

In its upperreaches the Fraser River enters the Rocky Mcun- tain Trenchby the Yellowhead Pass, a &ai: in the northern wall of the Trench oppositeTete Jaune. From this pointthe river flows north-westerlywithin the Rocky MountainTrench in which itt is imprisoned for a distance of 120 miles.Just above the Grand Canyon 103 milesup-stream from PrinceGeorge, the Rocky MountainTrench endsabruptly but temporarily. The southernwall merges i.n the Nechako Plateau, at thispoint, while.the northern wall terminates a few miles farther at the southwesterly-trending McGregor River Valley, which is about 12 mileswide at its accordantjunotion withthe Fraser River Valley. Bearpaw Mountains, which hereform the northern wall of the Rocky MountainTrench, rise to a height of about 3,503 feet above theFraser River, the elevation of the nor-tn-westend of this rangebeing 5,557 feet.

The topoeraphyboth to the north-east and to thesouth-west of the Fraser Riverin this region is noteworthy.There me six ciosel;f-.spaced parallsl northwesterly-trending mountain ra.nges to thesouth-west of thecentral ranges of the ilockyMountains al.1 of which terminatenorth-westerly at this point. These are, naming them from eastto west, the Eazaiko Mountains, McGregor Mountains,Bearpaw Mountains, Caribco Range (whichforms the southern wall of the Rocky Mou.ntain Trench, upstream from the Grand Canyon), the unnanedrange between the Bowon and 'Glillow Rivers, and the unnamed rangebetween the Killow and Fraser Rivers, at thenorth-westsrn end of which is "SixMile Mountain" to theeast of TaborLake.

At the northern end of the last threemountain rang's is a large valley of mature relief about 20 inilesin length'which trends directly across the direction of the majoraxes of the ranges; between thesouth-westerly and north-westerlytrending parts of the FraserRiver Valley. In short it forms a more gradualbend of the FraserRiver Valley than that occupiedby the river at its most northerly point and is followed by boththe Canadian Natio-?al Railwayand by the highway. This valley is largelyunfill

-7- -53-

Key map showing location of Figures 1, 2 and 3.

-8- thecourse of this valley near its mergencewith the Frase:r River Valley. On theother hand, the Bowrcn River,nearby,makesan abrupteasterly turn, flowingparallel to it untiljoining the FraserRiver. Rock-rims about a quarter of a mile apart,rise some hundredsof fee-t above and on either side of SagletLake.

The rise on thesouthern side of thelake is less sha:rpand the rim somewhat lower than on thenorth where it formsthe south- ernslope of a mountain,elevation 3,117 feet, in the central part of which is a granitestock. Easterly, the height of both rims of thisvalley decrease towards mereence with the Fraser River Valley somewhat down-streamfrom Hansard Post Office. It is apparent that the bottom of this valley can be but little abovetha-t of the FraserIiiver near Bansard station, elevation 2,006 feet. .As determined by altimeter on Aupst28th, the elevation of theFraser River at the end of themotor-road near iiansard station was only 20 feet below thelatter point. Tne elevationof Aleza Lake station is 2,307feet, that of Giscome 1,364 feet: and the Fraser River a.tPrince Georgeon thedate mentioned was 1855 feet.

Anothernoteworthy valley contains TaborLake, elevation 2,273 feet, and TsadestsaCreek which trends north-easterly between TaborLake and the 1,:illow RiverValley, near the north-wes-:ernex- tremity of the ranee dividing the Fraser and ';:illow RiverValleys. The elevation of theI;illow River at the junction of this valley is 2,105feet, th'e junctionbeing about S milessouth or" the western end of SagletLake. The topogr,F>hysuggests that this valley may representthe up-stream course of a formerlargt? drainage-system (for example the northerly Fraser Riverdrainage) throughthe Eaglet Lake - Aleza Lake - Hansard Lake Valley to the Herriok-McGregor River.

The break in the continuity of-the Rocky MountainTrench extends to thejunction of the Packand ParsnisRivers. There the Trench is of normal size and position in relation to the Rocky Mountainsand continues north-westerly without further interruption.South-east. of thejunction the Trenchappears tospl.it in-to two smallerbranches. The easterlybranch occupied by theParsnip Rivertrends in a south-easterlydirection, but far to the east of the normal position of the Kocky XountainTrench. The westerly branchoccupied by thePack and Crooked Rivers extends in a more southerly direction to the west of the normal position of the Rocky MountainTrench, gettingshallo.wer in this direction and finally merging intne Nechako Flateau at Summit Lake. The triangular-shapsd terrain betweenthese trenches becomes pro- gressively higher to the south-east reaching a maximum at the Arctic-PacificDivide, which trendsin a north-easterlydirection fromSumnit Lake directly across the normal position of the Rocky MountainTrench. One of thehichest points in the Arctic-Pacific Xvide,Averil Plountain, elevation 4,27'; feet,lies almost directly north-west of the end of the.RockyMountain Trench.near the Grand Canyon,where thenormal proportions of the Trench are restored and comtinuesouth-easterly without further interruption.

It is apparent(Fig. 3) that the bend of theFraser Rive.r after it .emergesfrom the Rocky MountainTrench near the GrandCanyon, is influenced by thedisposition of localmountain structures, although thevalley containing Hansard, Ale.zaand iagle-tLakes appears a more naturalalternative than the course followed by the river.

.Upon emerging from the Rocky MountainTrench,:the Fraser River enters the Grand Canyon 'incised .in.a low range of hills; and then. ,unconfinedby any hig,h wallsmeanders for a few miles at the extreme eastern edgeof the Nechako Plateau. Below theJunction of the McGregor River,the Fraser River makes the great bend at its most northerlypoint (Fig. 3), entering a valleyincisea between Averil Eountain,elevation 4,275 feet; on thenorth side of the river, and an unnamed mountain,elevation 3,117 feet on thesouth s'ide of the river. Here thedirection of flowchanges from.north-westerly to south-westerly;.In this region, the northern rim of thevalley rises sharply from the 'river to'form the flanks of AverilMountain, butthe rise ofthe valley-rim on'the south side' is less steep. Although this part of the valley is steep-sidedlocaliy androck- outcropsare numerous onboth valley-rims, there.is no suggestion of a canyon,and the.term "GisccmeCanyon"Gapp1ied to' the lower end of this part of the valley and so marked.on some maps is a misnomer. Below Tay Creek,the river again enters the Nechako Plateauproper, and aithough the depth of incisionincreases down- stream,there is marked topographiccontrast be'tween thoseparts of the valley 'below andabove "Giscome Canyon." Below it the valley considered as a whole is one of subdued relief with gently- sloping rims. Thisgeneral aspect is notobscured by the high banks of. glacial materials which flank the river on both sides at numerous pointsin this region. The number and size of thesein- creasetowards ?rince George, where the deposition of glacial drift evidently derived.botii from the north-west and.north-eastis particularly heavy. Giscome Rapids,almo.st 7 miles .in length, com- mence about 1 milebelow Giscome Portace. These rapidsappear to bedue tothe great accumulation of largeboulders washed out of the glacial debris.by the river in cutting: down through this material.

Below thejunction of the Nechako River at Prince George the FraserRiver flows almost due sauthto ivlites Landing.

Eighteenmiles below PrinceGeorge, the Fraser River enters theFort George Canyon, a rock-canyon 2 miles in lengthincised to a maximum depth of about '90 feet. It is apparentthat the can-' yon lies immediatelywest of a formerchannel of theriver, the down-streamend of which is cut by the'river at the lowerend of

- 10 - thecanyon. Bere the 6eviation of.the river fron its form.er channel has been very slight.

ZnerginE;from this canyon, the rivercontinues its southerly flow. Between thesouth end of Wood2ecker Islandand a 2ointjust belowthe mouth of Canyon Creek,the Fraser River Valley is almost gorge-likefor 1 1/2 miles. 80th valley-rimssteepen and theeast rock-rim rises abruptly to a height of some hundredsof feet above theriver. A shortdistance below Canyon Creek,the Fraser River Valleyagain assumes its character ofmature relief. These fea- tuxes suggest that the short piece of valleymentioned may be youngerthan that part of the valley aboveand below it, and,in conjunctionwith an embayment on the east side of theFraser River atthe south endof 1,ioodpecker Island,suggest that a segment of an older valley.lies buried to the east of theFraser River Valley inthis region. At WhitesLanding, the river makes anabrupt bend, turningsharply to the west to flow south-westerly past theJunc- tion of the !.lest Road River, and finally south-easterly to the point of entrance to the Co-ttonwood Canyon andbelow the latter to the mouth of the Cottonwood River.

There is sharptopographic contras-t between two parts of -this bend. BetweenSJhites Landing and the mouth of the \Vest Rosd River theriver-valley is oneof mature relief, whereasdown-stream from the mouth of the WestRoad River, the valley may best be dsscribed as a maturerock-gorce hundreds of feetin deptn. It is apparent that these two parts of the bendwere incised at different times, and tha-t theformer is olderthan the latter, which was mo:re rapidlyincised.

Another large valley now ,occupied by the northerly-flowing part of Canyon Creekand its tributary Pleadow Creek, lies consid- erablyto the east of theFraser River in this region. The east rim of this valley is formedby the western slopes-of the range of mountainsbetween the Fraser and SJillow Rivers. Rock is cut by all the'larger creeks (Government,Bixon and Terry, and the westerly-flowingpart of Canyon Creek)draining the western slopes of this range. To thesouth this rangemerges in tine plateau,but thedeeply-incised rock-canyons on Ahbau Creek and the Cot5onwood Riversuggest the southerlycontinuation of the eastern rock-rim. No rock-outcropsoccur on the western rim of this valley contigu- ous to the northerly-flowing part of Canyon Creekand Meadw Cree!:. Still farther to the west, however, imrediatelywest of Whitesland- ingCreek, rocks outcrop in a north and south direction.lulites- landingCreek having its source.in Lazaroff Lake, with many western tributaries whichmeander on the plateau, maintains an almost due northerly flo:Y to its Junction with the Fraser River, hcreas- ing its depth of incisionin the plateau down-stream. About 1 1/2 miles above its mouth it enters a rock-canyonabout half a mile in length,and 320 feetdeen, rock-walls being exposed for a height

- 11 - of 140 feet. From thispoint south rock-outcrops occur at inter- valsin analmost due sou-th direction(Figs. 1 and 2 ). Among the most southerlyrock-outcrops are the canyons on McIiardieCreek and its branohes,'and the' Cottonwood Canyon on the Fraser River. it has already been mentioned that the Fraser River occupi, as a maturegorge some hundreds of feetin depth between the mouth of the West Road R,iverand the CottonwoodCanyon. These facts sug- 'gest that the valley occupied by the northerly-flowing part of Canyon Creekand Meadow Creek is the unfilled part of a still larger valley trending in a southerlydirection from near Whites Landingand hounded by the rock-rimsmentioned and .joining the FraserRiver Valley near the mouthof the Cottonwood River. it is further.strongly suggested .that the Fraser River re-enters its former.valley,cutting through the western'rim at theextreme end of the, Cottonwood Canyon about 1 mile above 'the mouth of the Cot- tonwood River. The easterrrim of theancient valley in this re[,ion is the Cottonwood River Canyon at thehighway-crossing.

The topography of t"e FraserRiver below the Cottonwood River isdescribed on pages 6 to 11 of British ColumbiaDepartment of Mines aulletin No. S, 1943. The rampart-likerock-exposures, chiefly of the Upper Volcanics, whichcap the valley-rims of both theFraser River and its tributaries at so many pointsbetween Quesnel and Soda Creek;forming an outstanding topographic feature in this' region, werenowhere observed north of Guesnel in theregion examined. if therewere.flows of the Upper Volcanics they have. sincebeen eroded over a large area.

MaGregor River ""

The sou.thwesterly-flowingparts of the McGregor .Riverand SerrickCreek are virtually one and.the same stream,which.forms thenavigable waterway 0ccupyin.g a largesouthwesterly-trending valley, which is about 12 milesin width at its junction with ihe FraserRiver Valley. The northern wall of the Rocky Mountain Trench is terminated in this region by the gapcaused by this valley-junction. The water-systemindicated is forthe sake of brevitytermed the "Berrick-McGregor River'! in this report,' and its containingvalley Vne "Berrick-PicGregorValley." This waterway was ascendedby motor-boa-t as far as the junction of Fontoniko and SerriskCreeks, an estimated distance of 55 miles. On the northwesterly-flowingpart of the McGregor River a boatcannot be used owing to numerous canyons,whereas Herrick Creek is navig- able for a considerabledistance above the junction ofFontoniko Creek.Navigation above the Junction of JamesCreek is dangerous andshould not be attempted without a local pilot. From a boat on the Kerrick-MoGregorRiver it is very difficult to detect the junction of thenorthwesterly-flowing part of the McGregor River owing to the great width of thevalley, and to the number of parallelstreams into which thewaters divide. It is easy to pass

- 12 - from the McGrecor River to iIerrickCreek without perceiviq any differencein the volume of water.Although the northwesterly-. flowinzpart of the McGrefc'r l?iver is notnavigable, its volume may be ereater than AerrickCreek, but there can be no question that the largest and oldest valley in this region is theB:errick- IlcGreeorValley.

Near its junctionwith the Fraser Kiver, the flow of water in the McCreeor River is sluggish, the river meanders in the wide valleywith many ox-bow bends, and'repeatedly splits into a number of channels. Feat bogsoccur atseveral points in this part of thevalley. The velocity of thewater gradually increases up- strean. Frorr, a width of closeto 12 miles at its mouth, the Aerrick-McGregor Valleydecreases in size upstream to between 3 and 3 1/2 miles near the junction of thenorthwesterly-flowing part of the McGregor River. Its widthfurther decreases somewhat to its end atthe mouth of FontonikoCreek. The greatsize, depth of.incision, andmature aspect are noteworthy features of this valley. There are nohigh glacial banks within thevalley and few rock-outcrops dose to the river except in a rock-canyonabout 3 1/2 miles longand from 35 feet to 75 feet deep in which the river flows between points about 20 1/2 and 24 miles above its mouth. A gap in the canyonabout half a mile in length at about three-fifths of a mile above thelower end, divides the canyon into two sections: a down-stream sectionthree-fifths of a mile long, and anup-stream section somewhat under 2 1/2 miles :long.

The mountain-structure to the east of this valley is noteworthy.North of thePraser River andbetween it and the(central ranges of the Rocky Mountainsare three separate parallel, northwesterly--Lrendingranges, namely the Bearpaw,flcGregor and Dazaikoranges, all of which terminatenorth-westerly at the Eerrick-McGreyorValley. The Bearpaw rangeforms the northern wall of the Rocky MountainTrench, and the valley between it and the McGregor Mountains contains the Torpy River. The upper reaches of the McGregar River areconfined between the McGregor andDazaiko ranges,while the upperreaches of Herrick Creekflow betweenthe Dazaiko range and the western slopes of the central ranges of the Rocky Mountains. A notworthy example of trellis- type structurally controlled drainage is exkibited by the rivers inthis region. Tllese localranges all riseto elevations of not lessthan 3,509 feet above theriver-systems at their bases. Cn the northern side of theiierrick-McGreEor River Valley and the FraserRiver Valley below the junction, is anirregular mountain assemblage,along the high points ofwhich theArctic-Pacific Dividetrends north-easterly. The elevation of points on this divideincreases from little more than2,300 feet south of Sumit Lake to 4,275feet at AverilMountain, and to over6,503 feet (Fig. S) nearthe Rocky MountainDivide.

- 13 - Noteworthy is the fact that the direction offlow of large tributaries of the Herrick-McGregor River on the north-western side, is ascordant with a northeasterlyflowing parent stream, which suggests a possiblereversal offlow in the Herrick-?kGreg,or River. .-

There is a densegrowth of vegetation and underbrush in the bottomand lower valley-slopes of the north-westerly trending part of the Fraser River Valley and of the Xerrick-McGregorRiver Val- ley, and for the mostpart mountain-slopes are heavily timbered up to anelevation of about 5;OOO feet. The underbrush is markedly lessdense, andt,imber-erov&h less heavy in .tiat part ofthe Fra- serRiver Valley which is incised in the Interior Plateaux.

Nechako River

Only thelower 13 miles of the Nechako RiverValley was examined in'detail. A-brief examination was made of a few points farther up-stream in viewof their bearing upon the Fraser River Tertiary drainage-history.

After flowing north-easterly with many meanders in a wide valley of mature relief, the Nechako River makes a bend, 8 miles up-streamfrom Prince George, the directionof flow changing to south-easterly and easterly. Immediatelydown-stream from this bend.to its.,junction wit'n theFraser 'River at Prince GeOrEe, terraced flats of great size flank both banks of the Nechako River, save directlynorth of Prince George. This has formed a delta- likearea, extendinE mainly' sou.th of the river at the mouth of the Nechako River, on which the city of Prince George is situated. The lenrth'of this delta is about 6 1/2 miles and thewidth a6 the mouth is about 3 3/4 rniles(Fif:. 4). On thesouth side of the river this area.is bounded at its westernextrernity by a rock- rim about 675.feet in maximum height, Nhich rises sharply to the Nechako Plateau. On the northside of the Nechako Riverthe valley-rin rises even more sharply at the northern edgeof the delta-likearea, but consists wholly of banksof clay, sand, silt and gravel,about 3% feet inheight. The deposition of g:lacial 2ebris is heavy for many miles north of the river in this recion androck is obscured. So far as is known, -theonly rock-outcrop is Pilot Mountain,elevation 3,275 feet, an erosion remnant on which there is 'a "Look-out'' station, erected by theForest Branch of theDepartment. of Lands. It is about 5 miles due nqrth of the river(Fig. 2). Due tothe deepincision of theFraser and Nechako Rivers in this region, whichreaches an averagedepth.of about 570 .feet near the rivers, the delta-like area is hemmed-in on all sidessave by thegaps formed by river-valleys. Near tne mouth of this area are two prominentflat-topped, oval-shaped knolls. .?he distancebetween them is somewhat over a mils, and the elevation of the top of the more northerly is 190 feet above

- 14 - theFraser River; the more southerly is about 20 feethigher. It is clearthat these are erosion remnants, because a s1oue.h still existsat the northern base of eachknoll. The one at tkebase of the southern knoll, known as the "Iiudson Bay Slouch,"energes inthe Fraser at South Fort George.These sloughs undoubtedly indicate paths followed by the post-glacial waters of the Kechako Riverin cutting down through the great mass of glacial debris whichmust formerlyhave occupied the Nechako and FraserRiver Valleysin this region. A progressiveshift of thepost-glacial Nechako Riverchannels to the north indicates an attempt by this river to again occupy a pre-glacialchannel lying to the north fromwhich it was diverted. Although the slopes of the Nechako RiverValley are well-timbered, the underbrush is less densethan in the north-westerly trending part of the Fraser River Valley and h'errick-McGregorRiver Valley.

- 15 - GLACIAL GEOLOGY .. AlthoughPleistocene drainage-history is not pertinent to the subject of.this report; it was.foundnecessary to devote some time to the study of Pleistocene features to"differentiate between cer- tainPleistocene and Tertiarydeposits of lacustrine type. The attention of the writer was directed to one fact by C. C. Kelley of the Department of Agriculture which, it is believed, is not generally known. Within a large areacentering about Prince George, following or during the final retreat of'ice, but before restoration of drainage, a largelake, or lakes was formed adjacentto the FraserRiver'and its tributarydrainage-system. In thislake or lake deposits ofvarved clay were laid down on the top of the pre- existentglacial deposits. Many exposuresproving this were found at points within a radius of 20 miles of Prince.Gecrge and.fartier south inthe Fraser River Valley. Althoughde-bails of sec-tions are given subsequently in this report, it mightbe mentioned that exposuresinvariably show thevarved clay above tke glacial drift, but not alwaysdirectly above. Sometimes a few feet of river silt overliesthe glacial debris, indicating restoration of sluggish drainage for a brief period, followed by cessation of flow and formationof a lake. In Seme instancesthe varved clay is directly overlain by soil, in others by a few feet of post-clacial gravel. The varvedclay deposits ape apt to escape2etection unless examined closely,because from a distancethey closely simu- latedeposits of river-silt. The exactarea occupied by the glaciallake or lakes is beinginvestigated in detailin the course of thesoil survey of a largearea centering about Prince George now being undertaken by the Dominion and British Columbia Depart- ments of Agricu.lture,under the direction of C.C. ICelley ofthe latter Department.'Apart from its particularpurpose, this survey will be of direct' geologic interest and utility, not only becau.se of' theinformation supplied concerning deposits ofvarved clay,but inasmuch asthe survey involves a traverse of boundaries of all pre-emptionlots,.few if anyrock-outcrops will escapede- tection. The exactlocation of these in a large drift-obscured area wi1.l beof much value.

Fi'ithin that part of theFraser River Valley examined to date, it is evident that deposition of glacial drift within t'ne valley is responsibleonly for local and quite minor deviations of the presentriver fron it3 Tertiarychannels. As mentionedunder "Topography" the two bendsof this river originated before the Pleistoceneepoch. On theother hand, because the deposition of glacial drift within a large area centering in ?rime .George was heavierthan at other points, there is much to suggest that the course of the Nechako Rivernear Prince George hasbeen influenced by thedeposition of glacialdebris. The coursesof two successive post-glacialchannels of the Nechako Riverare plainly indicated by sloughs on thedelta-like area,near the mouth of thisriver. These

- 16 '- indicate the uncommon feature of a prop-essiveshift of thepost- glacialwaters to thenorth, in opposition to the southerly flow of its master-streamthe 3raser River. It is reasonableto sup- 2ose that the Nechako River was caused to bend to the south near Prince Georgeby t'ne reversal of flow inthe r'raser River from northerlyto southerlxin late Cretaceous time. The deposition of lacustrine,sedimentsin Tertiary time near the mouth of the Nechako River in its Tertiarychannel, followed subsequently by a great mass of glacial debris, may bethe reason for the shift of post-glacialwaters to thenorth. Before reversal of drainagein theFraser River, the Nechako Ziver may haveoccupied a channel considerablynorth of its presentcourse.

The nature and distribution of theglacial boulders leaves no doubt that the movement of the.ice-sheet across tiie Intsrior Plateauxwest of theFraser River was south-easterly. It is equally clear that within a large area centering in Prince George, drift was also derived from the south-westerly movement of an ice-sheet from the Rocky Mountains.This is provedby thedevel- opment of many roches mountonnees on the granite stock to the north of SagletLake, the 'south-westerly dires-tion of which plainly indicatethe south-westerly movement of theice-shee-t.

There is thus a mixture of drift from severalsources near PrinceGeorge. The boulders of batholithicrocks were doubtless derived mainly from the north-west, as were also the boulders of post-Palaeozoicrocks, whereas boulders of the Falaeozoic rocks may havebeen derived from either the nortii-west or north-east. Boulders of peissic rocks wereprobably derived from the north- east. Some of theglacial banks on thenorth side of the Nechako Riverare 465 feetin height. The numerous deposits of stratified sand, silt and clay which flank tne rivers indicate that the gla- cia1debris was cutthrough slowly.

In striking contrast to the heavydeposition of glacial drift in tiieFraser River Valley near Prince George is thealmost entire ab'sence of glacial drift in theadjacent Zaglet Lake - Aleza Lake - HansardLake Valley. This lattervalley is largely unfilled, andeven assuming that some drift was shifted by post- glacial waters it is improbable that much hasbeen removedby this agency. To supportthis theory there is anabsence of travel terracesflanking the rims of thevalley. The probablereason seems to be that the region in which this valley is situated re- ceived drift mainly borneby thesouth-westerly moving ice-.sheet.

The Fort George Canyon is a post-glacialfeature, and it is clear that a formerchannel of theFraser River lies buried. immediatelyeast of the canyon. The down-streamend of thisctannel is cut by the present river at the lowerend of the canyonand an excellentsection exposed. This channel is possibly of late

- 17 - Tertiary age, although it may be interglacial. The matter is discussed later in' this report under ."Terti.ary Fraser River Sediments."

The greatdepth of -theCottonwood Canyon suggests .that incision may havebeen commenced in Pleistocenetime. In thecase of this canyon also, a formerchannel of the baser River lies buried to the east, naqely the Tertiary Kine - Canyon Mine channel,describedin British ColumbiaDepartment of Mines.Sulletin No. 3, 1940, but this is of undoubted Tertiary age.

- 15 - BZD-ROCK GZOLOGY

Bed-rockgeology was studied primarily in connection with its bearing on Tertiary drainage-history as indicated bygeographic distribution,topographic position andform. In thecase of fossiliferous formations, age was determinedfrom palaeontological evidence,following exarrination of all specimensby the Palaecnto- logical,Section, Department of Mines and Resources, Ottawa, but no attempt was made to correlatewidely-separated rock-mtcro,?s. In descriptions of thelatter, the context renders clear that any'suggested correlation with known formations,based upon such:factors as degree of metamorphismand lithology can be regarded as ten- tativeonly.

Points of interest are:-

(a) The number of intrusivebodies in therocks cut.by the FraserRiver between the Cottonwood Canyon and a poini; west of 'ricodpecker .

(b)Batholithic stocks of considerablesizeoccur at the following points:

(1) Quartz-diorite on thewest side of theFraser River nearWhittier Cree!<.

(2) Diorite on thewest- side of theFraser River opposite IfcIlardieCreek.

(3) Dioriteeast of theFraser River west of a point about 4 milessouth of WhitesLanding.

(4) Granite,alaskite and diorite on tnesouthern rim of the Nechako River Valley near Prince George.

(5) Graniteto the north of ZagletLake.

(e) A tongue of dioriteintrudes limestone at the summit of the northernwall of the Rocky Mountain Trenc!?, to thenorth- east of Sinclair Mills.

In thedescription which follows, to facilitate reference, all exposures of thevarious Tertiary channels of theFraser Riverare grouped together and describedunder "Tertiary Fraser RiverSediments." Zxposures of sedimentsof the Tertiary Xest Road (Blackwater)River are also separately described under, "Tertiary WestXoad (Blackwater)River Sediments."

- 19 - Fraser River Valley

The GrandCanyon, about 9 mi1e.su?-strearr. from Sinclair Mills, is incisedin an isolated.rock-ridge of intra-valley.type situated.immediatelybelow the point at which thesouthern wall of the Rocky MountainTrench ends (C-eol. Surv.Canada, Sum. Rept'. 1839, pp.123-130). At tie time of examination it was not possib1.e to navigate the canyon, 'owing to the constant passage of logs, and for this reason only the' lower endof the canyon was examined. The rocksexposed ther's consist of anassemblage of interstratifiedbeds of quartzite,sandy limestone, shale and slaty argillite. 'Fossils were.found both in the shale and in the underlyinglinetone, at thelocality indicated (Fig. 3). Speci- mens were submittedto the Palaeontological Section, Department of Minesand Resources, and Dr. F. H. McLearn reportedthereon asfollows: Specimenfrom carbonaceous shale - "Containsbadly distortedspecimens of at least two species of trilobites, Olenellus, sp, and ____Bonnin, sp. T'ne preservation is too poor for identification of speciesand even too poor for exactdeiermina- tion of thegenus. The age is Lower Caqbrian."

Specimensfrom limestone underlying shale: "Contains the trilobite Bonnia,sp. The age is Cambrian,probably Lower Cambrian. ''.

Thisassemblage of rocks strikes mostly from north 37 to 72 degrees west and dips fron 32 degreesto 65 degreessouth-westward. At one goint a north-eastwarddip was observeddue to folding, and at anotherpoint a strike of north 73 degreeseast, with southward dip.There is some coppermineralization in these rocks.

One milebelow the GrandCanyon, is a smalioutcrop of lime- . stone on thesouthern bankof theriver, but no otherrock- ou.tcro?soccur close to the'river between this point andone about S miles below the mouth of the McGregor River.

The northern end of the BearpawMountains was ascended for the purpose&ofdetermining the bed-rock geology. ' This endof therange lies to the north-east of Sinclair Mills, andan indif- ferentfoot-trail about 7 miles in length, somewhat hard to follow, leavesSinclair Mills andswitchbacks up tiedensely- timberedmountain-slope. A triang,ulation-station of theDepart- ment ofLands, elevation5,557 feet, 3,500 feet above theFraser River, is at the sumnit of thenorth-western end of the Bearpaw Mauntains. The bad-rock at the summit of the.rangeconsists of wavy limesohist intruded by a tongue of fine-pained diorite 35 Ceetin width with a marginalphase of pyroxene porphyry. In the vicinity of thelatter the limestone shows a zone of silici- fication several feet in widthcontaining diopside and basic feldspar: The .limestonestrikes from north 2 to 12 deg,r'ees west

- 20 - 101 2 '4 6 x 10 12 Scdc 5Milcr

Fig. 1. Plan of FraserRiver extending from Williams Lake to Quesnel.

.. . .." and dips westward from 75 to 80 degrees. The sizeof the tongue was not determined but it may be considerable in view of the degree of alteration of the limestoneand because of thepresence of pebblesand boulders of batholithic rock in the creek-beds on themountain slo2es..

About three-quartersof a milesouth of the Fraser River, 2 l/Z milesnorth-weot of IIansard station on thesouth side of the motor-road(Fig. S), is anoutcrop of greyj.sh-whitelimestone about 15.3 feetlong and G5 feet hi!&.The limestone is massive and strike anddip are not clearly defined. Apparently the strike is north 29 degreeswest and the dip 75 degreessouth-westward. About 1 milenorth-west of thisexposure, also onthe :south side of themotor-road is another small outcrop of limestone. These outcropsappear to form thesouthern rim of the valley now occupiedby Eaglet, Aleza and Hansard Lakes, near the mergence of thisvalley with the Fraser River Valley. The limestone is possiblythe same age as that exposed inthe GrandCanyon. Outcrops ofthinly-bedded limestone, strike north 42 degreeswest, dip 27 decreessouth-westward, occur on thenorth andsouth banks of the Fraser Rivar about 7 1/2 miles down-streamfrom the month of the McGrecor River,and also approximately 1 mile down-streamfrom this point. A mall outcrop of thinly-beddedschistose quartzite, strike north 67 degreeswest and di;, 83 degreesnorth-eastward, canbe seen on thesouthern bank of the Fraser about 1 milelower down.

About -5 milesup-stream from Averil Creek, a smallcreek, locally named Fish Creek,flows almost due southinto the north side of theFraser River. A large,grey-ooloured, cliff-like rook-outcrop,the most prominentrock-exposure inthe neighbour- hood, visiblefrom the river, occurs to the east of theheadwaters of this creek. approximately 2 miles northerly from the Praser River. Zxanination proved this to bethinly-bedded, grey-white limestone, strike north 39 degrees west and dip 60 degreesnorth- east.Tie top oT thiscliff-like exposure is 1,030 feat above theriver. Coarse-pained quartzite, strike north 32 degrees west and dip 45 degreessouth-westward, outcrops to thsnorth-east of thi-sexposure, 525 feet above the river.

Rock-outcro9sare numerous at and near the most northerly point of theFraser River from Averil Creek down-strea:n for about 4 miles, whore theFraser River Valley is steepsided, and inthe lower part of AverilCreek Canyon. All thesestrike nostly fromnorth 42 to 72 degreeswest and are pronouncedly :nicaceous andschistose. They comprise silicifiedquartz-muscovite schists, quartz-biotite schists and quartz-sericite sshists and are radically different lithologically from the rocks hitherto described on this and the Herrick-McGregor River. About 1 mile above its mouth Averil Cree!< emergesfrom a deeprock-gorge some miles in

- 21 - lengt'n, of which the lower 2 miles wereexamined. Tbe xalls of the gorgeare some hundreds of feet in height and affordan excellent crosc-section of themicaceous rocks. kt a point 3 milesfrom the FraserRiver, the micaceous rocks are apparently overlain by limestone on theeast side oi" the'canyon. Thesemicaceous rocks may be of Precambrianage. The scheeli-te-bearingquartz veins in this regionare described in the Annual Report,Minister ofMines, &-it- ish Columbia, 1935, pp. C30 to C32. The micaceousrocks do not outcrog near the river below a point 3 miles down-streamfrom Aver- il Creek.Between Giscome Canyon andPrince George, rock-outcrops are few.Zxposures of'sediments ofthe inter-volcanicFraser RiveEoccur at points 1 1/2 and 5 miles down-stream from Giscome Portaze,and aredescribed subsequen.tly under "Tertiary Fraser Rivzr Sediments." A smalloutcrop of argillite,strike north 37 degreeswest, dip 20 degreesnorth-eastward, occurs on theeastern side of the river approximately 1 miledown-stream from the last point. Schistosegreenstone is 'exposedthree-quarters of a mile down- streamfrom the mouth of the Xillow River on both sides of the river. At thispoint on theeast side of theriver greenstone with some intercalated tuff beds is exposedover a length of 1,050 feet and height of 120 feet. Theserocks strike nortn 8 to18 degreeswest and dip Prom 53 to 70 degreeswestward. Exposuresof interstratified congldnenerate andsandstone on theeastern bank of the river somewhat over 3 miles to the north of Shelley,are believed to represent the Socene or earlierpre- volcanicchannel of theFraser River and aredescribed later. Between thelast-mentioned exposure and Prince George, no rock-outcrops occurnear the river, but to the east the Nechako Plateau may be but thinly covered with glacial debris as low rock- outcropsare not infrequent. Almostdue east of PrinceGeorge, immediatelyeast of TaborLake, is themountain known locally as "Six-MileMountain" elevation 4,125 feet, atthe northwestern end of therange between theFraser and i~lillowRivers. The rocksexposed on Six-MileMountain, and on the Nechako Plateau to the eastconsist of schistosesediments and intercalate'd volcanic flow-rockslocally intruded by tongues of batholithicrock. The averagestrike is north 10 degreeswest and the dip 20 degrees tothe west. Theserocks contain slightly cupriferous and aurif- erousquartz veins from which doubtlessthe placer-gold found on SkaretCreek in this region was derived (see Annual Reports of theMinister ofMines, Zritish Columbia, forthe years 1932, 1933 and1934). South of Prince George there are no outcrops on the river banks for a distance of 18miles, except clays and other members of thelacustrine deposits aboveand below Tabor Creek, described under"Tertiary Lacustrine Deposits."

The riverthen enters the Fort GeorgeCanyon, a steep roclc- walledcanyon, the length of which is about 2 miles and maxinum

- 22 - 4Nukko Lake

White Mud Rapids

. ~ .. height of walls 90 feet. As will,.beseen (Fig. 2), rock-outcrops are frequent in a length of 4 miles of the river in this region. These rocks consist of anassemblage of wide alternating bands of andesitic and basaltic volcanicflow-rocks and limy ar$illites probably of Kesozoicage, which strike from north 12 to 4:? degrees west and dip from 35 degrees north-eastward to nearly ver'kical. A prominent member of this assemblage is a porphyrywith phenocrysts of hornblende which is locally much fractured andweathered to a deep-redcolour owing to the development of hematite in the numerous fractures. An outcrop of this red-coloured rock occurs on the east side of tie Fraser River just above thejunction of Red- rockCreek. Redrock Creek enters the Fraser River in a gorge85 feet in height incised in well-lithified conglomerate of note- worthycoarseness. A11 pebblesand boulders therein are water- worn and some are between 3 and 4. feet in diameter. The matrix appems to be mainly derived from andesitic and basaltic rocks. Overlying t'ne conglomerateare interstratified argillite md coarse-grainedsandstone. These rocksstrike north 50 depees westand dip 35 degreesnorth-eastward.

On thewest side of theriver, opposite a point 2 1/% miles down-streamfrom Stone Creek, there is a small outcrop of ?or- phyritic flow-rock with phenocrysts of hornblende.

On the east bank of the river 1 1/2 miles above the mouth of TrappingCreek, coarsely-crystalline basalt resembling basalt of the Lower Lavasof Eocene or earlierage, outcrops over a height of 35 feet and length of 300 feet. Small diorite sills about 6 inches in widthintrude the separation-planes between the lava flows.

Just below the mouth ofTrapping Creck, is a small outcrop ofthinly-bedded limestone strike north 14 degreeswest, dip 45 degreeswestward. A quarter of a milefarther down-strear on the sae side ofthe river, are small outcrops of andesite and basalt

Between a point 3 milesdown-streaT from Trapping Creak, and thesouth end of Woodpecker Island, the river runs over bed-rock in many places,and rock-outcrops on bothbanks are frequent. On thewest side of theriver opposite the first point,and on the east side of the river three-quarters of a mile down-stream from. it, argillites strike fromnorth 40 to 54 decreeswest andclip' from 50 to 80 degreessouth-westward. On theeast side of the river they are apparently intruded by a tongueof porphyri.tic rock with phenocrysts of biotite.

Much metamorphosedand contorted argillite, which may be of Palaeozoicage, is exposed on theeast side of the river for a distance of somewhat over a mile further down-streamand on the oppositebank of the river. This rock is intruded by1arp;e chloritizedacidic tonpes. On bothsides of theriver at; the

- 23 - southernend of Woodpecker Islandare large outcrops of calcareous argillite and quartzite, strike north 67 westand dip 53 degrees south-westward. On theeast side of theriver at-this point fossils werefound inthese rocks (Fic. 3). A specimen was sentto the Palaeontological Section of tine Department of Minesand Re- sources,and Dr.. F. H. ?lcLearn reported as follows:"Contains fragments of a pelecypod,Ealobia or Daonella., TheaKe is Triassic."

On the east side of theriver the Triassic rocks form the northern end of a largerock-outcrop which rises to a heightof severalhundred feet above tie river, andextends southerly for 1 3/4 miles,forming the eastern rim of the valley in this region. Volcanic rooks probablyof Mesozoic age with a few intercalated bedsof argillite,overlie the Triassic rooks near the northern endof the large rook-outcrop mentioned, but vegetation obscures thecontact. These volcanicrocks are exposed almos-t continuously on thePacific Great Zastern Railway grade, 383 feet above the river, for 1 1/2 miles to the sout!l of theTriassic rocks.

On the east of the river 1 1/2 miles down-streamfrom the southend of Woodpecker Island,and on thewest bank of the river oppositethis point, are low outcropsof argillite of indicated Mesozoicage intruded by diorite. The argillitestrikes from north 50 to 87 decreeswest and dips from 50 to 75 degrees south- we stward.

;irg,illite of apparent Mesozoicage intruded by dioritio tongues, is exposedhalf a mileabove the mouth of Canyon Creek on the east side of theFraser River and on thewest side of the riveropposite this point in ccreek-bed. The argillitestrikes north 87degrees west and di2s 75 dep"res.southward.

Canyon Creek is contained in a steeprock-walled canyon for a distance of 1 1/2 milesabove its junctionwith the Fraser River,and the mouth of the canyonforms a prominentrock bluff on theeast bank of theFraser River at thissoin-t. The rock' in the canyon is wholly slaty artillite, intruded bynumerous small dioritic tongues. The argillite strikes north 77 degrees west and dips 55 degrees southward. Tine age may be Palaeozoic.

Outcrops of sediments of .the inter-volcanicFraser River occur on both sides of the river near Xhites Landingand are subsequentlydescribed under "Tertiary Fraser River Sediments."

Rock exposuresnear the Fraser 2iver are mostly a few feet in height, except near its confluence.with the West Road River. In this part of theFraser River Valley are exposuresof sedimentsof the Tertiary West Road River which are described later.

- 24 - On thesouthern bank of the river half a mile down-:;'cream fromthe mouth of \.!hiteslanding Cree::, slateoutcrops at the river's edge foralmost half a mile,strike north 51 degreeseast anddip 36 degreessoutkn-eastward. The slate is intrude?%by tongues of diorite. On thenorthern bankof theriver, approxj- mately 3 milesdown-strean from WhitesLanding Creek, beds of slate and interstratifiedlimy quartzite, much contorted,are intruded by acidictongues.' Small quartz gash-veins are devel- oped inthe sediments and intrusivebodies. The slate ma.y be Pa1aeozoi.c.

Three-quarters of a mile down-streamfrom the exposure of slate on thesouthern side of the river is anoutcrop of dark- bluelimestone, strike north 52 degreeswest and dip 75 degrees nor-En-eastward.

Two miles down-streamfrom the last describedexposure on thenorthern bank of the river, argillite intercalated with schistosevolcanic rocks, strike north 34 degreeswest with nearly verticaldip, is intruded by a dioritetongue. This exposure underliesan exposure of Tertiarysediments of the Nest Road River.

On the eastern bankof the river 2 1/2 miles above the mouth of the !.:est Road Riverschistose grey-black quartzite is exposed, strike due east and dip 40 degreessouth. Sirnilar rocks are exposed on thisside of theriver 1 miledovn-stream. Half a mile farther down-stream on the s&?e side of theriver an outcrop of schistosegreenstone strikes north 48 degrees east and dips 35 degreessouth-eastward. In -thetime available it was possi'sleto examine only a few of therock-outcrops situated athigh elevations between the :

From 1 1/2 milesabove McSardie Creek down-stream to the end of t'ne rockexposure 1 mile aboveCottonwood River,the schistose rocksexposed closely resemble those of the Cache Creek series.

On the east bank of the river 1 1/2 miles aboveMcIiardie Creek schistosequartzite outcrops strike north 72 degreeswest and dip 75 degreessouth-westward. On thewest side of the river oppos3.i;e this point a largeoutcrop of diorite form:; the westvalley-rim. McEardieCreek flows in a deepgorge incised

- 25 - in schistosesediments, which erds 1 mile above its mouth. ii bluff of granitic rock occurs one milebelow this creek, on the eastern bankof theFraser 2iver. At thehead of the Cottonwood Canyon quartz-diorite outcrops at the mouth of XhittierCreek and on thebank.of the river opposite this point intruding schistose sediments. The Cottonwood Canyon is. about 1 mile in length;the depth at its headof about 375. feet decreases down-stream to where theriver emergesfrom it atthe Tertiary Mine. Rock is exposed, on bothsides of the river for upwards of a mile farther down- stream. The rocksexposed in the Cottonwood Canyon and on both sides of the river below the canyon areschistose: q.uartzite, limestone,and argillite. Theserocks strike north-westerly and dipsouth-westward mostly at steepangles. Between thelast describedexposures and Soda Creek,with the exception of a small outcro? of argillite on thewest side of the river 1 mile above limn Creek, no outcrops of pre-volcanicrocks (those olderthan the Lower Lavas of Zocene or earlier age) werefound on either bank of theriver. 2aker Creek Canyon is incisedin sediments which at one point are overlain by valley-fill occurrences of the Lower Lavas.Rampart-like exposures of the Upper Volcanicsin. BakerCreek and largeoutcrops of theLomr iavas occurring on thewest side of the river near Narccsli Creekand on both sides of the river betweenMacalister and Soda Creoksare described in British ColumbiaDepartment of NinesBulletin Xo. 3, 1940.

Exposures of Australian members (a) of the r'raser River formationoutcrop at various points from 5 miles north of Quesnel tothe Alexandria Perry, a distance of somewhat over 33 miles. Largeexposures of these sediments occur near Quesnel (where the unconformablecontact between these sediments and the Lower Lavas is exposed at low stages of water in the bend of the river three- quarters of a milebelow Guesnel); at Rich Bar, 4 miles dcwn- stream from Guesnel; 1 1/2 milesbelow Rich Bar on both sides of the,river;on..Australian Creek; on thewest side of theriver opposite Australian Creekand near Alexandria Ferry on bothsides of the river. 'Between Soda Creekand Chimey Creek the river is incisedwholPy'in sediments resemblinc the Cache Creek series.

.Region east of theFraser River between Whites Landing and ~ - . .. .. - - the mouth of the Cottonwood River " A reconnaissance was made of this region to delimit the rock-rims of an ancient..valley, which is now largely filled save at its northernend. The existence of thisvalley is suggested by features enumerated under "Topography"and 'its occupancy by some ,of theTertiary Fraser River channels proved by the occur- rence of sedimentsdescribed subsequently.under "Tertiary Fraser RiverSediments.'' The approximate.2osition of thisvalley is indicatedin Fig. 1, of British Columbiailepartment of Mines 3ull.etin KO. 3, 1943.

- 26 - The most southerlyrock-exposure of thewestern rim is cut by theFraser River about 1 mile above the Cottonwood River (Fig. l), fromwhich point rook is exposedcontinuously t.o the head of the Cottonwoo'd Canyon on bothsides of the river, save for the gapcaused by the crossing of the Tertiary Mine - Canyon _I_ -I'Iine channel. At thispoint, the Fraser River after having left its formervalley at XhitesLanding, and making a detour to the westaround it, againre-enters it, cuttingthrough the western rim.

Zxposures to the nortk of thelast-mentioned point are dis- tributedin an almost due northand south line to the west of !!hiteslandingCreek.

Thinly-bedded fissile argillaceous quartzite, resem'oling quartzite of the Cache Creek series,strike north 23degrees east and dip 25 degreessouth-eastward at elevation 2,665 feet, are cut by a small tributary of VhiteslandingCreek 3 1/2 milesnorth of LazaroffLake.

To t'ne northof the last-described exposure the Fraser Plateau becomes hilly, and at several places to the west of a point ap- proximatelyfour miles south of !.kitesLanding outcrops of diorite occur,and at one pointlimestone apparently of Mesozoicage is intruded by diorite. These lastoutcrops occur at elevations of between2,600 and 2,680 feet on a series of rockyridges, distrib- uted in a north and south direotion.

An outcrop of argillite apparently ofMesozoic age intruded by diorite,occurs 340 feet above the bed of thecreek about 1 1/2 milesnorthwesterly from the last point. In the bed of the creek, 1 3/4 miles above its mouth, argillite intruded by diorite is alsoexposed. A shortdistance below thispoint the creek enters a rock-canyon. The rockexposed in the canyon is chiefly carbonaceousargillite intruded by diorite tongues. A small outcrop of andesite occurs at the lowerend of the canyon. The argillite strikes north 59 degreeswest and dips 53 degreesnortn- eastwar2. The rooksexposed in this canyonresemble those of Mesozoic age.

To the east of Canyon Creekthe east rim of the anoient valley is more clearly defined topographically than the west Tin, as it is formed by thewestern slopes of the mountain range dividing the valleys of theFraser and i!illow Rivers, whichmerges southsrlyin the plateau-like region near Ahbau Creek, and the Cottonwood River. The westernslopes of themountain-range are drained byHixon Creek and its tributary Government Creek; by TerryCreek, and by the westerly-flowing part of Canyon Creek. Bed-rock is exposed at variouspoints on thesecreeks; some hundredsof feet above the floor of the valley containing the northerly-flowing part of Canyon Creek.

- 27 - Government Creekwters a deep rock-walled canyon somewhat over 1 mile above its junction withExon Creek. At the upper and of the canyon -the rocks are argillite intruded by tongues of batholithic rock. Tne arrillite may beof Palzezoic age. U1- stream the creek cuts a seriesof thinly be2ded fissile schistose sediments. In places the strike is east with dip to the northof about 45 degrees; at other points the strike is north47 degrees west, with dip of about45 degrees north-eastwaru. An occasional dip to the south-westwardwas observed. Similar schistose sediments are exposedon Hixon and Terry Creeks, and at all these 2oints resemblethe schists of the Cariboo series, though they may be of Palaezoicage. About 3 miles above its mouth, Hixon Creek cascades over falls 60 feet in height incised in augite-syenite. About2 miles farther up the creek, fissile schistose sediments are exposed in the bed of the creek andon the valley rims at different 2ointsfor a distance of about1 mile. The sediments strike mainly north40 de- gre-s west, and dip north-eastward at steep angles. The character of the rocks changes about6 miles above the mouth of the creek and from thispoint up-stream.for about half a mile on both sides of the creek,. silicified bioti-te schists are exposedat intervals. These also strike north-west and dip north-eastward. The contact between these rocks and the fissile schistose sadiments is not exposed. The fissile schists somewhat resemble members of the Cariboo series.

About 5 miles above its mouthon its northern bank, Terry Creek cuts schistose argillite, strike north1.8 degrees east, dip 65 degrees eastward. The creek wasnot examined above this point in 1943,.and no previous detailed examinationof the exposed bed- rock had been made.It is reported however that the bed-rook exposed at various points up-stream consists of metamorphosed schistose,sediments with some intercalated voloanics intruded at various pointsby tongues of batholithic rock. At about6 miles above its mouth tie creek flows through a rock-gorce and at about 7 miles above its mouth is containedin a rock-canyon about 1030 feet in length, the wallsof which are aboutSO feet in height.

Canyon Creek andup-strem from a point 3 miles above its junction with Headow Creek,is contained in a steep-sided canyon- like valley for a lengthof about4 miles. The rocks exposed in this gorge are volcanic flow-rocks and argillite intruded at one point bya tongue of batholithic rock.

Australian mernbers (a) of the Fraser River formation are exposed on the west bankof Canyon Creek, approximately4 miles down-stream from its junction with Meadow Creek. 36.8.At miles north of .Cuesnel, the terminusof the Pacific Great Eastern Railway, a branchmotor-road leaves the highway and leads to the eastside of Canyon Creek,crossing the railway-grade hilt beyond Quesnel on the west side of this creek about half a milefrom the highway. The aboveexposure is reached by followingthe railway- gradesoutherly for half a milefrom the road crossinc. The exposure is on the bank of the creek about one hundredfeet west of the point indicated on therailway-grade.

At thispoint, interstratified clay beds containing seams of lignite of a maximum thickness of 1 1/2 feet, andbeds of fine gravel,overlain by coarsegravel containing pebbles up to E inchesin diameter, have been gently folded into a syncline. The exposurewhich rises vertically fromthe water's edge on the west bankof the creek is 303 feet long and 45 feet high, and is uncon- formablyoverlain by a few feet of post-glacial gravel.

At theup-stream end of thisexposure the following section is afforded. At thetop of thebank; soil and post-glac.ial gravel 5 feet;lignitic clay, 2 feet:coarse gravel, 13 feet; lig,n%.ticclay 2 to 3 feet;coarse gravel, 12 feet; sandy clay bedswith seams of lignite(one ofwhich is 1 1/2 feet thick) 10 feet. The base of thesandy clay beds is atwater-level. The sedimentsstrike north E degreeseast and dip 35 degreeswestward.

The CaribooSyndicate under the direction of D.D. l.+aserof Quesnel,sank a shaftin 1929 immediately up-strean on a small bench on the same side of thecreek about 5 feet abovewater- level.This is now full of water,but D. D. Fraserstates that the shaft was sunk to a depth of E5 feet, dis.closingthe continuation of alternatingbeds ofcemented graveland silt dipping about 26 degreeswestward. There was a noticeable amount of micapresent in both silt and gravel.Pebbles in the gravel were largely of graniticrock. From thebottom of this shaft a hole was boredwith a Keystone-drill which reachedg.ranii;ic bed- rock at a depth of 150 feet below thesurfacz. This hole was con- tinuedfor a distance of 15 feetin bed-rock. The drill-holedis- closed a continuation of the gravel and silt beds with much lignite.

Distant 840 feetsouth of this shaft on thewest side of the PaciricGreat Zastern Xailway-grade, a tinicknessof 35 feet of poorly-sortedcoarse sub-angular gravel-beds, strike northerly and dip 30 degreeswestward, is overlain by 55 feet of well-sorted gravel,horizontally stratified. The imbrication of thelatter indicates a northerly flow of the waters by which they were laid down, presumablythose of Canyon Creek. The pebblesin the in- clinedgravel are largely derived from granitic rook. The total lengthof this exposure is 180 feet andheight 90 feet. Vegeta- tionconceals the uppermostfew feetof the exposure. On. the eastside of thePacific Great Eastern Railway-grade, distant

- 29 - 3,033 feet southerly from the shaft, cemented beds of coarse sub-angular [ravel,with pebbles u? to10 inches in diameter,are exposed at intervals for a length of 230 feet and hei@ht of 25 feet. The bedsstrike north 53,degrces east and dip 30 degrees south-eastward,and are overlain byfrom 5 to 13 feet of post- glacial and glacialgravel.

The threelast-described exposures plainly indicate that beforethe Australian members (a) of theFraser River formation werefolded, there was a strongflow of waterover them, possibly causedby the Fraser River breaking t'nrough a dam of the Lower Lavas. Thisfeature of coarsetilted g,ravel overlying Australian members (a), is exhibited at ot.herpoints subsequently mentioned.

About thrje quarters of a miledown-stream from the Cariboo Syndicate's shaft is ancutcrop of well-lithifiedsteeply-diTping conglomeratebeds, which is believed to exemplifysediments of thepre-volcanic southerly-flowing Fraser River, and is described vnder "Tertiary Fraser River Sediments ."

&bauCreek a quarter of a mile a'bove the junction of &Torn Creek,emerges from a rock-walledcanyon. The totaldepth of incision in the plateau-like region at this point is about 430 feet, and rock is exposed to a height of 200 feet above thecreek. The rock exposed.at the lowerend of the canyon is volcanic breccia which is in.i;rudedby tongues of fine-grainedacidic rook.

The Cottonwood River is crossedby a bridEe on the Prince George-,Guuesnel highway at thelower end of a stee?-rvalledrock canyon. The rocksexposed at thispoint are volcanic flow-rocks probably Mesozoic in age.

-Herrick-McGregor River Valley

The southwesterly-flowingparts of Herrick Cr,eekand the McGregor Riveroccupy one and the same valley, which for brevity is called in this report the "Herrick-McGregor RiverValley.'! BurntMountain lies to the west of the junction of Fontonikoand HerrickCreeks (Pig. 3) and the elevation of its summit is 5,910 feet. In thecentral part of thismountain is a glacialcirque, the floor of which is at elevation4,915 feet and the walls can bereadily climbed. 4s faras could be determined, all slopes of thZsmountain drain into Fontoniko or HerrickCreeks. Immediately to the west is another hic,hermountain separated from Burfit Moun- tain by a dee? valley (Fig.' 3). The Arctic-PacificDivide passes overthe summit of thishigh mountain, (the elevation ofwhich appeared to beover 6,500 feet) the drainage of its south-eastern slopesbeing into Fontoniko and Herrick Creeks, and that of its northernslopes into the upper reaches of theParsnip'River. Viewed fromBurnt Mountain, the pronouncedsynclinal structure of.the upper part of this high mountain was plainly evident.

- 33 - , (I Pre-Volcanic Fraser RiveF,,&diments ,. . .,. . I .. : !li ' JURA-CRETACEOUS . .. Granite, 8-a quartz-diori

Schistose sediments, %a, possibly Palaeozoic

Gneissic rocks and micaceous schists

0 5 Motor-roads "- "-

1012 4 6 8 10 12 SC& -"~ Mils Fig. 3. Plan of FraserRiver extending from Prinoe George to Monhn Pass. \ The lowerslopes of Burnt Mountain arecovered with dense vegetationand timber-growth up toelevation 3,215 feet, above which a bush-firepassed many yearsago. On the lower s:lopes acd at thebase of themountain, rock-outcrops emerge at several points. These outcrops compriseschistose quartzite and thinly- bedded argillite,strike fromnorth 53 to 72 degrees wes-t, dip about45 degrees south-westward. From thefloor of theglacial cirqueto the summit, theformation whereexposed on thenorthern sideconsists of schistoselimestone, strike north 43 degrees westdip 63 decrees north-eastward.

Save in the canyon,rock-outcrops are few, close to the river inthe Herrick-McGregorRiver Valley. About 3 miles aboveJames Creek on bothbanks of BerrickCreek dolomitic limestone outcrops, strikenorth 52 degreeswest, dip 65 degreessouth-westward. Near the mouth of OtterCreek, mainly down-stream from this point for a distance of somewhat over 1 mile,are four rock-outcrops consisting of crenulatedargillite, andthinly-bedded quartzite. These rocks strike fromnorth 22 to 77 degreeswest and dip north-eastward at steepangles. At 7 1/2 milesbelow the junction of the northwesterly-flowingpart of the McGregor River on the northern bank interstratified,fine-grained quartzite and argilli-testrike north 72 depees west and. dip 73 degreessouthward. One mile down- stream from the last exposure, on Vne northern bank of the river, is an outcrop of limestone, at some pointsthinly-bedded, at others massive. About 24. miles above its mouth the McC-regor Ri-Jer enters a rock-canyon. A gap in the canyonabout half a milein leneth, at aboutthree-fifths of a mile above thelower end, divides the canyon into two sections; a down-stream section three-fifths of a milein length, and an up-stream section somewhat less t!lan 2 1/2 milesin length. The height of thewalls of tie canyon varies from 33 feetto about 75 feet. In theup-stream section, describ- ingthe outcrops in their order fromthe head of the canyon down- stream:

(1) fissile,thinly-bedded, interstratified argill.ite and limestonestrike north 23 degreeswest and dip 75 degreessouth- westward,

(2) one mile down interstratifiedargillite and quartzite contain irregular and discontinuousquartz lenses of maximum width 2 1/2 feet, which followthe bedding-2lanes of thehost- rocks. These rocksstrike north 47 degreeswest and dip 65 depees north-eastward,

(3)at a point 1 1/2 miles down, differentialweatllering has formed a pillar 23 feet high of much fractured quartzite contain- ingresistant quartz gash-veins. The quartzitestrikes north 42 degreesriest and dips 75 degreesnorth-eastward,

- 31 - (4)immediately adjoining down-stream, fissile blue and cream-colouredlimestone much drag-foldedand containing numerous calciteveins is interstratifiedwith quartzite. The formations strikenorth 12 to 22 degreeswest. The dipat some points is 55 degreessouth-westward, atothers 73 decreesnorth-eastward.

The lower section of the canyon is incisedwholly in quartzite. -The bedsvary from 3 to 12 inchesin thickness-with,argil- laceouspartings, which arethe cause of differentialweathering at sorpe points. The strikevaries from north 42 to 57 degreeswest withdips varyin:. fron 75 degreesnorth-eastward to nearly vertical.

EiCh.i milesbelow the canyon on the northern bank of the McGreCor River, lime schist is exposed,strike north 27 degrees west,dip 63 degreessouth-westward. At thispoint the planes of schistosity strike north 42 detreeswest cutting the bedding planes.

The rocksexposed in theSerrick-XcGregor River Valley resemble those.exposed at the loalerend of the GrandCanyon.

Nechako River .Tall%

Only thelower 13 miles of the Nechako RiverValley was examined in detail. Because of theexistence of the Lower Lavas at certainother points, and theevidence of damming bythem, an examination was made of this river at two upstream points namely at the Isle de PierreXapids.and %%ite Mud Xapids,and also of a regionnear the mouth of its largetributary, the Chilako River. These lavasare mainly of basalticcomposition and some of the outcro7sare large. Reasons for correlation with t'ne Lower Lavas are :

(a) A11 outcropsare of thevalley-fill type in contra- distinction to the topographic position of the Upper Volcanics which normallycap the valley-rims andform the floor of the InteriorPlateaux.

(b) The anele of inclination of theseparation planes be- tweensuccessive lava-flows is generally much steeperthan in thecase of the Upper Volcanics.

(d).In one instance,described subsequently, 1ava.eruption was undoubtedlycontemporaneous with the deposition of beds of fossiliferou'sdiatomaceous silt. Palaeontologicalevidence in this caseindicated an Upper 3ocene or Oligoceneage. In the Eorseflyand Kamloops areas the end point of the Lower Lavas is indicated by theemission of enormous quantities of ash in late

- 32 - Zocene time, which continuedinto the-OliEocene. In the ikchako andChilako River Valleys apparently lava eruption continued during the period ofash-emission in the southern regions.

Isle de PierreRapids. These rapids may bereadily reached by a branchmotor-road 6 1/2 miles in length which leaves the highway at a point 32 mileswest of PrinceGeorge.

Near theIsle de PierreRapids (Fig,. 2) theriver flows due southand occupies a valley of mature relief considered as a whole, although banks of unconsolidated material rise sharply from near theriver. The Isle de PierreRapids; somewhat overthree-quarters of a milelong, incise the Lower Lavas,which occur as a typical valley-fill, and rock is exposed up .to pointsabout 50 feet above theriver. The valley-rimsare not steep close to the river. Above therock exposures the valley-slopes are covered with dense vegetationand timber growth. Here the Lower Lavas consist'of basalticflows, breccias, andagglomerates strike north 11 degrees east and dipabout 45 degreeswestward. Locally they are deeply weathered.

It is apparent that originally the Nechako Rivermust have been obstructed or dammed at .this point by the eruption ofthe'se lavas.

White Hud Rapids. These rapidsare about 1 1/4 miles d0.m- streamfrom Bednesti Station. A car may betaken to the top of the south valley-rim directly above the rapids by following a branch- roadabout 3 miles in length from the.Chilakoroad. The latter leavesthe highway 15 mileswest of Prince George. The total distance by road from the latter place to the rapids is about 23 miles. On thesouthern bankof theriver, on theCanadian Na- tionalRailway right-of-way, 25 feet above theriver, about 1 mileeast of BednestiStation at several points in a distance of half a mile, a;.e outcrops of Lower Lavas.These areandesitic incomposition and strike about north 12 degreeswest and dip about 40 degreeseastward. The lavasare deeply weathered and theoutcrops have been converted into masses of white and red- oolouredresiddal clay. Reducing acids resulting from decompo- sition of vegetablematter have doubtless been active in decol- ourizingthe clay. Presumably these rapids owe their name to thedeposits of whiteclay in this region. Thinly-bedded limy shale of possible Xesozoicage outcrops between the exposures of Lower Lavas on therailway.

The rivercuts -through older rocks, exposing in its bed massivepyritized andesite of possible Mesozoicage, somewhat down-streamfrom the most easterlyexposure of the Lower Lavas. Schistosecarbonaceous argillite, strike north 47 degreeswest, dip 75 degreesnorth-eastward is exposed 300 yards up-st:ream from the andesite on thesouthern bank of the river.

- 33 - A detailed account of the lower 13 milesof the n'echako River Valley follows:

At Canadian National Railway Nile-post 13 (13 miles west of Prince George) a small creek flowing north-westerly enters the southern bank of the Xechako Iiiver (Pig. 2). Near the riverfor a length of 303 feet the creek has cut downa maximumto depthof 85 feet, through20 feet of unconsolidated glacial and post- glacial materials overlying beds of compacted areillaceous diatomaceous silt 65 feet in thickness. The lowest beds exposed are black, while those at the top of the exposureare shiny black, except on the southern sideof the creek where cutby the railway- grade 55 feet above the Nechako River, the colour is greyish- white. These last ?roved fossiliferous, and specimens were sent to the Falaeontological Section, Departmentof Mines and Resources, Ottawa. Dr. Walter A. Bell, Chief, Palaeontological Sectionre- ports as follows: "Except for oneor two indeterminate stems the fossils consist of a sing.le species of dicotyledonous leaf, iden- tified asxndus " SF. aawson. Dawson's type specimensof this species seemingly were collected from Blackwater IiYver,so with little doubt from the same formation. Sapindus is perhapsa doubtfvl reference, for the species is muoh like some of Yne live oaks. The light-grey siltstone in which the leaves are embedded is quite diatomaceous, and the leaves are very well preserved showing most details ofthe venation. The ageof the formation cannot of course be defined froma single species, but undoubtedly is of thesame Tertiary age as the plant-bearing beds of Quesnel; presumably Upper Eoceneor Oligocene."

The lower beds of silts-tonein place appear almost black, but on drying, the colour changes to grey. At the lowest point of exposure of the siltstone beds,20 feet above the river, chloritized basalt of the Lower Lavas outcrops and underlies the siltstone beds. Farther up the ,creel: numerous small dykesa few inches in thickness intrudethe siltstone beds, and numerous mall bonbs occur in the bedding planesof the siltstone. On the northernbank of the creek near therailway-cutting isan intercalated scoriaceous bedof lava 4 feet thick exposedfor a length of 10 feet. It is apparent fromthe exposures that volcanism was in progress during. the deposition of the siltstone beds. The attitude of the siltstone is poorly defined. At the lower end of the exposure, below the railway, where a small bed of fine gravel 15 inches thick is interstratified with the siltstone beds, the strike is north 58 degrees east, and thedip about 30 degrees south-eastward. At the upper end of the exposure, on the northern side of the creek, the siltstone, which is here not diatomaceous, strike north 12 decrees west, anddip 45 degrees south-westward, is intruded by dykesof basalt about 2 feet wide.

Distant 220 feet in a north-easterly directionfrom the mouth

- 34 - of the creek described on thesouthern bank of the iiechako River, a bed of lignite 6 feet in thickness, strike north 42 degrees east anddip 35 degreossouth-eastward, is exposed at river-level for a distance of 70 feetalong its striks.This bed is overlain by claybeds of anexposed thickness of. a few feet.Distant 340 fee-t in a north-easterly direction from the lignite is another bed of anexposed thickness of 5 feet, of similar strike anddip partlycovered by water atthe time of examination.This is traceable for a distance of 60 feet along its strike, and is stratigraphicallylower than the first bed. It is directly underlain by beds of carbonaceousshale, and grey and black non- diatomaceoussiltstone. Chloritized basalt of the Lower Lavas outcrops for a length of 150 feet at theriver's edge, 525 feet upstream from the mouth of thecreek.

Three-eighthsof a mile to the north of this creek, a large outcrop of Lower Lavas ooours to the east of therailway-cutting, 60 feet above the Mechako .River,and smaller outcrops we:re observed at points in the railway-cutting between this point and Miworth.Although theactual contact is notexposed, there can be but little doubt, in view of theclose proximity of the exposures to one another that the lignite seams and thebeds of shale, siltstone and clay containing them directly underlie the diatoma- ceousand fossilferous siltstone beds. These described

Two miles down-streamfrom Miworth, the Xechako Riverchanges its direction of flow fromnorth-easterly to south-easterly. In this region a feature of the river is theextensive terraced delta-like area which extends to its junction with the Fraser River atPrince George.This delta-like area is bounded on the northern and southernsides by highvalley-rims (FiE. 4) where its width is 3 3/4 miles. On the northernside of theriver gravel, silt, sandand clay banks rise to a height of from 340 to 465 feet above the river, but no rock-outcropsoccur near the river. On thesouthern side on theother hand, the Pim bounding thedelta- like area is composed for a lengthof 6 1/2 mileswholly of rock, and rises to a maximum height of 675 feet above the river to tne plateau-level. To thesouth, this rim continuesto its mergence with theFraser River Valley. To tienorth near Otway theheight of the rim decreases. On thesouth side of theriver between Otway andMiworth on theCanadian National 3ailway right-of-way 55 feet above theriver, are frequent rook-outcrops, whichsugge?,t that the covering of glacial debris may be thin and that a rock-rim may bscontinuous between these points. The rocksforming. the high rim on thesouthern side of the Nechako Riverare schistose peen- stone,quartz-chlorite schists andthinly-bedded carbonaceous

- 35 - I s

Fig. 4. Plan of Nechako River Delta.

- 36 - argillite; striking fromnorth 17 to 22 degreeswest, dLps mos-ily steep and notless than. 75 decreeswestward. Occasional. strikes tothe nortih-east wereobserved. This assemblage is intruded by a stock or cupolaof batholithic rock of considerable si.ze at the northern end,phases of which are granite,alaskite, and diorite. Reference to mineralization in theserocks will befounc. in the Annual Report of theMinister ofMines; British Columbia, 1926 under"Largeasse." To thewest of thehigh rock-rim, tk.ese rocks compose knolls on the Nechako Plateau,evidently erosior. remnants, or monadnocks. On theCanadian National Railway right-of-way half a milewest of Otway, pyritizedlimestone underlying quartz- chlorite schist is intruded by alaskite tongues several feet in width. Tieintruded rocks strike due northand dip 35 degrees west. Half a milewest of thelast-described exposure in the railway-cutting,quar-tz-chlorite schist, strike north 67 degrees west,dip 35 degreessouth-westward, is intruded by alaskite tonguesvarying from a few inches to 3 feet in width.

Immediately east andwest of Miworth station, and on the east side of themotor-road below the station, chloritized andoarbon- atizedschistose rocks strike north 3 degreeseast, dip 50 degrees eastward,are exposed over a considerablearea.

On the north side of the river between Miwortin and prince George,search failed to reveal any rock-outcrops. On this side of the river, the nearest known rockexposure in this section is on PilotRcuntain, about 2 milessouth-westerly from Swamp Lake. The elevation of the summit of this mountain is 3,275feet or about 960 feet above theplateau. Partly argillaceous a,nd schistose quartzite is exposed a shortdistance below and at the summit of thismountain, strike fromnorth 22 to 48 degreeseast, dip 5O degreesnorth-westward. Quartz veins 'were observedin t:le quartzite.

The Chilako River was examined at points between l mile and 2 miles above its junctionwith the Nechako River,and the evidenceobtained clearly indicated damming of this river is{ eruption of Lower Lavas. In thisrerion three points were observed at which tine rivercuts through the sediments of its Tertiary channelintercalated with flows of pillow-lava of the Lower Lavas. Distant about three-quarters of a milefrom the mouth of the river on theeast bank,one such exposure (overlain by 16 feet of glacial debris) is 150 feetin length and 90 feetin height. At this point theintercalated beds of sandstoneand pillow-lava are in places horizontal, and inother parts of theexposure dip.about 15 de- kreeseastward. One hundredyards up-s.tream on thewest bank of theriver is another some%rhat similar exposure. About one mile fartherup-stream on the east bank of the river is a cliff-like exposureof extremely vesicular basaltic lava, 70 feet high and 200 feetlong. At some pointsare intercalated horizontally

- 37 - stratified beds of sandstoneand diatomaceous material a few inchesin thickness. Distant one hundredyards to t'ne east of this exposure on the east rim of the valley of the.river are well- .stratified volcanicbreccias. These arehorizontal, and are deep$weathered. Immediately tothe north of thesebreccias is a large boll composed of fine-pained basalt of the Lower Lavas. The 'separation planes between successive 'flows strike due east and dip 15 degreesnorth.

- 35 - TZRTIARY FRASZR RIVER SEDIMZNTS-

In classification as "pre-volcanic"the following criteria are deemed essential:

(a) Entire absence of constituentgrains or pebbles composed of Lower Lavas or youngerrock,-formation.

(b)Likelihood of stratabeing tilted as considerable movement is known to havetaken place subsequent to eruption of the Lower Lavas .

Pre-volcanic Fraser River

Sediments of this river werefound at three widely-separated points :

(a) On theeast bank' of theFraser River about 10 miles southof Quesnel for approximately 1 1/4 miles upstream from Sisters Creek.

(b) On theeast bankof thenortherly-flowing part of Canyon Creek nearly due east fromWhites Landing.

A description of each of theseexposures follows:

(a)This exposure may bereached from the highway at a point 10 milessouth of Quesnel where the FraserRiver flows a fewhun- dredyards from the highway.

At this point over a length of 750 feet and heikht of 220 feet,beds of alternatinginterstratified conglomerate andsand- stoneare exposed at the river's edge. These strikenorth and dipfrom 25 to 30 degreeseast. Owinr.to differential weathering, theexposure is pinnacledand as it risessheer from the river's edge its scenicaspect is impressive. The pebblesin the conglom- eraterange from 1/4-inch to 7 inchesin diameter and are composed of diorite,granodiorite, and schistoseandesitic lava. Although poor sorting is evidenced,.imbrication is distinct and indicates thatthe water in which thesesediments were deposited fl.owed southerly. The exposure is overlain byabout 10 feet of post- glacial and glacialmaterial. In the upperpart of Dog Prairie Creek, a smallstream flowing westerly into the Fraser River at a point 1 1/2 miles up-streamfrom Sisters Creek, the tor' of thesesediments is exposed,and there they are considerably

- 39 - weathered and are staineda deep-red colour. This is probably a preserved re.mnant of Tertiary weathering.

(b) The exposure is reachedby following a branch motor- road, which leaves -the highway 36.8 miles north of Quesnel, and crosses-tothe east side of Canyon Creek. The bridge across Can- yon Creek isa little more than halfa mile from the highway and the exposure is about300 yards downstream fromthe bridge.

At this point steeply-dipping, wsll-lithified bedsoon- of glomerate, sandstone and silt are exposed a forlength of 250 feet over a height of 25 feet. These are unoonformably overlain 100by feet of well-sorted horizontally-stratified gravel. Overlying the latter is 60 feet of glacial material including boulder-clay with a considerable thickness of silt in the upper part.

'The steeply-dipping conglomerate, sandstone and silt beds contain some carbonized driftwood and somelipitic clay seams. They strike north 27 degrees westand dip steeply south-westward. The pebbles in the conglomerate range from3 to 6 inches in diameter and are derived from batholithicrocks, quartzite, grey-black cherty quartzite, argilliteand andesite. At least 25 per cent. of the pebbles are composed of batholithic rocks.No pebbles derived from Tertiary volcanicrooks are present. These strata show evidence of considerable movement along the bedding-planes.

The well-sorted horizontally-stratified gravel which overlies the steeply-dipping beds may be of interglacial age.

(c) The exposures may be readily reachedby walking along the Canadian National Railway line north-easterly from Shelley station.

%ell-lithified beds of sandstone overlying conglomerate are exposed in the railway cutting at Mile-pos-t 133 (133 miles west of MoBride), 3.3 miles north-east of Shelley station. The length of this exposure is 270 feet and the maximum height on the east side of the railway-cutting is4.0 feet. The elevation of the railway above the Fraser R.iver thisat point is 35 feet.

The beds strike north 54 degrees eastand dip from 25 to30 degrees north-westward. The pebblesin the conglomerate range from 4 to 10 inches in diameter and are largely composedof hard resistant rock. The majorityare'grey quartzi-te, buta proportion, possibly ten per. cent. of the total, are composeda greyish- of white, feldspathic rocknow kaolinized. Imbrication suggests a southerly flow. Enfortunately no fossils were found in this exposure, and although the beds containa small amount of silicified driftwood, the state of preservation a ofspecimen submitted to the Palaeontological Sec.tion of the DepartmentMines of and

- 43 - ResourcesOttawa proved too poor for determination of age. The degreeof lithification suggests an early Tertiary if not late Cretaceousage.

Distant 300 yardsto the' south-west of the aboveexposure on the east rim of theFraser River Valley which rises immediately east of therailway-line, sandstone beds overlying conglomerate bedsare ex2osed over a length of 250 feet. The top of this exposure is 75 feet, and thebottom 25 feet, above themilway, but densevegetation somewhat obscuresthe exposure. At this point thebeds strike north E degreeseast and dip about 10 degreeswest- .wardand the exposure may be near the top of an anticlinal fold. At 25 feet above the railway an old adit has been driven in the conglomeratebedsfor 63 feet on a bearingsouth 37 degreeseast. Samplesfrom this adit assayed nil in gold, but this horizon is certainly many feet above thebed-rock of thechannel. In this aditthe pebbles range in diameter from 2 to 0 inches,and the majorityare of grey quartzite. Imbrication, although no-t con- clusive,indicates a northerlyflow of water. Balf a mileto the south-westof the first-described exposure on theeast side of the railway-cutting is anoutcrop 33 feet long by 10 feet high mostly of sandstonewith a conglomeratelens.

At a point 2 1/2 milesup-stream from Shelley conglomerate bedsare exposed at.and below river-level for a lengthof about . 53 feet. The extent of thebeds at water-levelcannot he ascertained owing to theaccumulation of sawdustfrom a nearhy saw- mill. Quitepossibly search on theeast rim of theFraser River Valleyto the south-west of thisconglomerate would reveal extension of these beds.

It is apparent that thedescribed exposures arethose of a deeply-entrenched river of largeproportions and distant headwaters. The position .is likelyclose to the former junotion of the Nechako River and thenortherly F'raser River drainage. As theexposure does not afford a sectionnear bed-rook, it is not possible to eain information as to the terrain reached 'cy the headwaters.i'lcreover, but litble information as to the direction of flowcan be gleaned from the2ebbles contained in the conglomeratebeds. These pebblesare largely derivedfrom a resistant rock,quartzite, which indicatesflow for a lengthy period,.but as quartzite is exposednear the Fraser iiiver to the sou.th of this point as well as to the north on the Fraser andBerriok- PIcGregor Rivers(see "Bed-rockGeology"), obviously evidence of direction of flow is inconclusive, as is theconflicting imbrica- tionat different points. The deep incision may suggest a southerly flow of water, and conflictin& imbrication may possiblybe due to eddy currents due to junction of the Nechako and.Praser Rivers. Noteworthy is theabsence of pebblesderived from nearby rockssuch as the schistose greenstone exposed about 5 miles

- 41 - to the north, or t'ne micacaous schists at the north bendof the Fraser2iver. The latter are of resistantcharacter, but the formerare less resistant than quartzite. The greykaolinized feldspathicpebbles i.ihich are present to a smallextent in the conglomerate.mightconceivably be derived from granitic rock, which occursnear Zaglet Lake, and also to the south at thenorthern endof the range between the Fraser and Killow Rivers, and in thesouth rim of the Xechako iiiver Valleynear Prince George.

intra-LowerLavas Fraser River I - _" Zxposuresof sediments of this river are given in British ColumbiaDepartment of Ilines Bulletin Fo. 3, 1940,an additional exposure was discoveredduring the year, which is of particular value,as the age is supported by palaeontologicalevidence.

Thisexposure is on thewest side of BakerCreek 2 1/2 miles up-stream from its mouthand may be a preservedremnant of the down-stream continuation of theriver-channel on theplacer claim of X. Blair (see Annual Report of theMinister of Mines, British Columbia,1938, pp. C36 to '339). It is 1,600feet north 46 degrees east from the latter.

At this point an isolatedoutcrop about 200 feetlong, of white quartzite, rises sharply from thewater's edge'on the west sideof BakerCreek to a height of80 feet above thecreek. The upper 40 feet of the quartzite is much decomposed and i.s directly overlain by a total thickness of about 12 feet of thinbeds of tuffaceousgrit, gravel and clay. A flow of the Lower Lavas 3 to 4 feetthick, extensively kaolinized, of a salmon-pinkcolour, capsthe exposure. The lavaflow is directlyoverlain by soil and a littleglacial debris. Some ofthe beds of grit contain small seams of lignite, and in onebed is a veinlet of fibrous bariteabout 3/4.-inch thick. T'ne followingsection is givenat the highestpoint of theexposurer soil 2 feet: lava-flow, 3 to 4 feet;tuffaceous grit-bed (with small seamsof lignite and veinlet of fibrousbarite 3/4 inchthick) 6 to 8 inches;gravel bedfrom 15 inches to 4 feetcontaining pebbles 2 inches in dianeter composed mainlyof schistose quartzite and argillite with some quartz;tuffaceous grit-bed, S inches;bluish-coloured claywith seams of lignite, 4 feet; decomposed and-kaclinizedrock, a?parentlymainly quartzite, Sut some decomposed lava may alsobe present, 4.0 feet;quartzite to creek-level, 40 feet.

The sedimentsstrike north 52 degreeswest and dip 15 to 23 degreesnorth-eastward.

At the northern endof this exposurethe beds of tuffaceous gritcontdned fossil leaves. The followingsection was exposed: at thetop, soil, 1 foot,kaolinized, red-coloured lava-flow, 3

- 42 - feet;tuffaceous grit-bed, 6 inches;gravel-bed, 15 iaches; tuf- 'faceousgrit-bed, 9 inches;gravel-bed, 9 inches;tuffaceous grit- bed, 2 feet;gravel-bed, 9 inches. The recionimmediately below is obscuredby vegetation but quartzite outcrops in the creek below.

Specimens of the fossiliferous grit-beds weresubmitted to thePalaeontological Section, Department of Minesand Resources. Dr. \!alter A. Bellreported as follows: "The leavesare too broken to be identifiable.' Seemingly theyrepresent a species of birch(Be-tula) like Betula macro&lla Beer. -. The age I thinkis probably UpperZocene orOligocene."

Zxposures of TiltedCoarse Fraser giver Sediments Immediately __""_I_ "" "-Over- Austr'alian Members (a) of Fraser Eiver Formats ""_ """_I__

Althoughbeds of sand,.clay and fine sub-angular {gravel interstratified with lignite beds form the Australian members (a) of theFraser River formation in mostcases, at some pointsex- posures of gravelare of such a thicknessand the constituent pebbles so 'large,from 4 to 10 inches in diameter, as i;o indicate that before tilting of Australian members (a) the flow'of the FraserRiver was restored over the basins in which the lignite deposits Kereformed. To avoid undue complexity,these sediments are mapped asAustralian members (a) (Figs. 1 and2)'artd not 'as separateFraser River. sediments. Zxtensive ex2osures c,f thetype indicated occur on both sides of the Fraser River at the' water's edg,e to the north. of Dog Prairie Creek 7 miles south of2u.esne1, and also on Canyon Creek(previously described).

On the west side of theFraser River somewhat north of a pointopposite Dog Prairie Creek, four seams'of 1,igniteand interstratified clay beds of a total thickness of,'1? feet, .ire overlain by 100 feet of g,ravel;. The. strike is north.'40 to 77 degreeswest and thedip 20 to 40 degreessouth-westward. The horizontal length of this assemblage is 350 feet and the vertical height 85 feet. These tiltedstrata are unconformablyand directlyoverlain by 14 feet o.f boulder-clayand glacial gravel; The glacial material is overlain by 20 feet of horizontally-stratified post- &+.cial' river-silt.

On'theeast side of theFraser River opposite, andup-stream fromthe last-described exposure, are extensive outcrop:; of gravel beds strike north 22 degreeswest and dip 40 degreesnorth-eastward. At theup-stream end these gravels conPormably overliebeds of ligniteand clay. Themaximum height of theseexposures is 75 feet above'the river, andthey are unconformably o+erlai,n by post- glacialbeds of graveland sil-t a few feet in thickness. To avoid undue complexity,however, such sediments are not classified separately.

- 43 - -Inter-Volcanic Fraser___Iliver Sedimentsof this formationare exposed'at Giscome Rapidsand at a point 5 milesnorth of Cuesnel.(Figs. 1, 2 and 3). Wumerou-s exposureseast of the Fraser RiverValley, between those on Canyon Creek and thosenear the mouth of the Cottonwood River,prove that theinter-volcanic Fraser River occupied a valley considerably to theeast of thepresent Fraser River Valley in this region. This ancient valley,was boundedon the west by therook-exposures trending from Laiaroff Lake in a northand south direction immediatelywest of \,!hiteslandingCreek. The rock-outcrops on both sides of the FraserRiver between the Cottonwood Canyon and the mouth of the Cottonwood River are the most southerlyexposure of thewest rim of thi's valley. The valley is bounded on the east by high-lying.rock-'exposures on Government,Hixon, Terryand westerly- flowiq part of Canyon Creek,by the rock-canyon on Khbau Creekand that on the Cottonwood River at thehighway-crossing. Exposures of sediments on the Cottonwood Rivercomparatively close to those at the double hairpin bendof theFraser Rivcr 10 miles north of guesnel,even allowing for meander's, indicate a river of great width.

Between theexposures of thesediments of theinter-volcanic FraserRiver onCanyon Creek.andthe Giscome Rapids, there is a long gap. Consideringthe topography.of this part of theFraser Riverin conjunction with the form andgeographic distribution of rock-outcrops,there is everyreason to believe that up-strem frombioodpecker Islandthe course of thepre-volcanic southerly- flowingFraser Iiiver and all subsequentTertiary channels of the Fraser River deviated but little from that of the ?resent Fraser Ziver. There is little doubtthat between Canyon Creekand 2cod- peekerIsland, the course of theinter-volcanic Fraser River lay immediatelyeast of thehigh rock-rim which is continuous on the east side of theFraser River in this region.

Below Canyon Creekexposures prove that for a shortdistance the course of the inter-volcanicFraser'River coincided with the FraserRiver.. Zxsosures on WhiteslandingCreek prove.that the course of the forner river 'nn'9s approximately duesouth of Whites Landing within the ancient valley.

The exposuresof sediments of theinter-volcanic Praser River aremainly large, such as those at the double hairpin bendof the FraserRiver 10 milesnorth of Quesnel; on the east bankof the FraserRiver above b%itcs Landing and on bothbanks of Canyon Creek,down-stream from the junction ofHixon Creek and on Ahbau Creek. Some ofthese are close to half a milein length and the heightexceeds 203 feet. The impressivesize of theseexposures sugg.ests thelong life of the river and the enormous amount of ension accomplishedby i-t. The nature of thepebbles indicates that far headward erosion was accomplished by this river.

- 44 - Distinctivefeatures of thesesediments are:

(1) The strata arehorizontal or nearly so.

(2) The pebblesin the lowest gravels range in s:ze from 6 to 8 inches, and arederived frox resistint rooks such asgrey and garnetiferousquartzite, an:! gneiss. These rocksare exposed up-stream from Giscome Canyon exceptthe last which is known to occurnear Tete Jaune. ' Imbrication is pronouncedand j.n all cases inciicates a southerlyflow. Lit'nification is welladvanced.

(3) The size of thepebbles decreases from the base upwards and the uppermostbeds in some exposuresconsists of sand or clay.

The foregoingfeatures are common to all exposures. In some thereare thick beds of white or cream-colouredclay in.di.cating approachto lacustrine conditions. Tie cream-coloured clay found at a point on the Fraser 2iver 25 milesup-stream from Prince Gaorge, is suitable for themanufacture of hig.h-grade refractories. As in some instances,beds of ligniteoverlie the clay, doubtless the purity of the lattor is due to thereducing action of the former on percolatingwaters oontaining iron in solution.

The locations of exposures of sedimentsof the inter-volcanic .FraserRiver are shown on (Pigs. 1, 2 and 3).

(a)9alf a milebelow Uhiteslanding Creek on the,nestern bank of theFraser River is an exposure of particulardiagnostic value.There a thickness of 35 feet of typicalinter-volcanic' FraserRiver sediments is inmediatelyunderlain by.10 feet of sediments of the Tertiary \:estgoad River atriver-level. The inter-volcanicFraser River sediments are directly overlain by 4 feet of post-glacial. gravel, which is again overlain by 4 feet of river-silt. The totallength of thisexposure is 353 f.eetand the height about 50 feet. . The sedixlents of the Tertiary We& Road Riverare quite distinctive owing to the number ofpebb1.e~ of grey-blackoherty quartzite present. This exposure is of particular value in proving that the West Road,Riverjoined the inter-volcanicFraser River near this point, and that drainagein theformer was reversedsubsequently.

(b) On tie westbank of UhiteslandingCreek, half a mile above i-ts junction with theFraser River, are two exposuresof sediments of theinter-volcanic Fraser River, 60 feetapart; the distancebetwezn them is coveredby vegetation. Their average heieht is 125 feet, and thelength of one exposure is 60 feet and theothsr 150 feet. The gravelbeds a-t the base of theseexposures show pronouncedimbrication, indicating southerly flow of thestream depo.sitingthem. The pebblesrange in diameter from 4 to 6 inches, andalthough rnainly derived from grey quartzite, show a commingling

- 45 - withthe grey-black quartzite characteristic of thegravel of the Tertiary"est Road River. At one point a dark-colouredstratum in thegravel, G inchesthick, contains much secondarypyrite.

(c) At thelower end of bcqiteslanding Creek Canyon on .the top of theeast canyon-wall, 130 feet above thebed of the creek, a thicknessof 11 feet of sandand fine gravel contains at the base a seam of lig,nite 5 inches thick, overlain andunderlain by white clay a fewinches in thickness. The lower clay is underlain by bedsof sand and pave1 of a total thickness of 20 feet which rest directly on bedrockforming the canyon-wall. A number ofthe constituentpebbles in the gravelare grey-black quartzite. This exposure is directly andunconformably overlain by an exposed thicknessof 60 feet of boulder-clayand glacialmaterial. Sigher pointsare concealed by vegetation. A nearapproach to lacustrine conditions and also comminglingof the Tertiary '&st Road River and theinter-volcanicFraser River are indicated.

(d) A numberof exposures of sediments of theinter-volcanic FraserRiver occur on Moau Creekbetween the lower end of the canyonand the junction of the creek with the Cottonwood River, andfrom that point along the Cottonwood River to its junction with theFraser River. This indicates very plainly that the inter- volcanic Frassr River was deflected south-easterly at Ahbau Creek canyonby the rock at that point and at the canyon on the Cottcn- wood River.

Zxposures on Ahbau Creekhave added interest because most of thesediments of tneinter-volcanic Fraser River are overlain by boulder-clay, which is againinmediately overlain by varvedclay. The significance of the latter has been previously discussed under "GlacialGeology." Its presencehere is indicative of thesize of thelake occupying the Fraser River Valley following the final disappearance of ice and prior to -res-toration of drainage.

On the eastern bankof Ahbau Creek, 1 1/2 miles above Cinerna, sediments of the inter-volcanic Eraser Riverare exposed over a lengtki of 150feet and height of 55 feet. The exposureconsists of we1.l-sor-tedimbricated gravels with a lensof sand, and is directly overlain by 4 feet of boulder-clay on top of nhich rests G feetof stratified silt. Distant150 yards upstream is a larger exposure 250 feet long and 150 feethigh. At thispoint the section of thetotal exposure is as follows: on topunderlying dense timber-growth, silt 15feet; varved clay, 30 feet; stratified silt, 20 feet;boulder-clay andg,lacial gravel, 40 feet;sedimentsof inter-volcanic Fraser River consisting of well-sorted gravel,45 feet, extending to creek-level.

Largeexposures of sedimentsof the inter-volcanic Fraser Riveralso occur nsar t'ne lowerend of iihbau Creekcanyon a short

- 46 - Plate I A. Pinnacle in Tertiarygravel of theinter- Plate I B. Differentialweathering in intra-Upper volcanicFraser River at the Big Bend, 10 Volcanics - sedimentslying between lava milesnorth of Quesnel. beds,near Macalister. distanceabove Ncrn Creek. Near the lowerend of the canyon there is a gap inthe high rock-walls about 1,033 fee’; lory, and in this gap are two largeexposures of theriver-sediments. Gown-stream fromthese the rock-canyon continues for several hundred fee-t, but this part of the canyon is incisedimmediately to the east of tine river-sediments which are again exposedim-nediately below the end of therock-canyon.

At the upper end of the gap is anexposure of the riversediments 300 feet long, and thefollowing section is a.fforded: atthe top underlying timber-growth and soil, silt, 5 to 13 feet; varvedclay, 5 to15 feet; boulder-clay, 25 feet:well-sorted imbricatedgravels lithification of which is welladvanced, 125 fee.’i,. T”e constituentpebbles range from 3 to 6 inchesin diameter and are derived mostly from grey quartzite and garnetiferous quartzite. Anotherexposure 300 feet down-stream shows consider- ablecross-bedding. This regiori is probablyJust at the point at which the direc-tion of flow in the river changedfrom southerly tosouth-easterly, andcross-bedding is to be expected.

(e) On -he eastern bank ofthe .Fraser River 1 1/2 milesbelow Giscome Por’caije, sediments of tine inter-volcanicFraser River are exposed for a length of 303 feet,and the following section is afforded:at the top, soil, 2 feet;varved clay, 25 feet;boulder- clay and glacialgravel, 20 feet;well-sorted coarse gravel, 10 feet;yellow sands and clays, 40 feet;sediments of theinter- volcanic.Fraser River mainly coarse well-sorted gravels, 50 feet extending to river-level.

The pebblesrange from 4 to 6 inchesin diameter and about 73 per,cent.are composed ofserici-tic peissic rock, 20 percent. are of purple-colouredquartzite, and -the remainder of >white quartzite andquartz. The gravelsare horizontal andhave a dead-whiteblenched appearance. The overlyingyellow sand and clay and also the zcarsegravel overlying the latter may be of interglacialage. Possibly some lig.nitebeds, originally overlay the gravels of theinter-volcanic Fraser River and have :sincebeen eroded. The originalpresznce of lignitebeds might account for theabsence of oxidationin underlying beds.

(f) Somewhat over 3 1/2 miles down-streamfrom tnelast exposure a deposit of whiteclay occurs which is believedto be theclay member frequentlypresent in the sediments of the inter- volcanicFraser River. The olay is .atthe base of anextensive densely-timberedbench which flanks the west side of the Fra’ser River, and is exposed atseveral points a shortdistance above river-level for a distance of about a quarter of a mile. No work hasbeen done on the property for years and original open-cuts havesloughed badly. This clay is a high-gradechina-clay ty?e, and?

Intra-U;:per Volcanics Fraszr Xver

Largeexposures of sediments of this riveroccur Just below the Fraser Plateau near the top of the east rim of the Praser RiverValley to the east andnorth-east of Macalister.These are almostcontinuous for a distance of half a mileeasterly from Macalister,and one isolatedexposure is aboutthree-eighths of a milenorth-easterly from the skne place. James il. Macalister kindlypointed out all exposures known to him.In this region t'ne elevation of theFraser Ilateau is about3,030 feet, or 1,620 feet above theFraser River. The plateauhere is drift-covered and near the edgeslopes gently downward towardsthe top of the eastvalley-rim of theFraser River, which is formed'ofcharac- teristic cliff-li!:eexposuras of the Upper Volcanics. The exception is theisolated exposure lying. north-easterly from Macalisterin which thevolcanics overlie the sediments, below which talus andveEetation obscure tine valley-slope.

These exposures of river-sedimentsand associated stratified water-lain breccias are well-lithified and exhibit locally pro- nouncedcross-bedding. Save inthe case of theisolated exposure north-easterly from Xacalister,exposures are larce, exceeding one hundred feetlong and fiftyfeet high. The sedimentsare in most cases directly overlain by pillow-lava, and umderlain by highly ~~ typicalsection: Thichess in Feet Top of east rim of Praser RiverValley Columnar basalt 103 ?j.llow-lava 20 Sediments - constituentsrange in size from pains less thanan eig.:ltn of an inch to pebbles 3 inchesin diameter - horizontal 20 Cross-beddedsediments and breccias 30 Basaltic vesicular lava - horizontal 50 Sediments - horizontal 15 Cross-beddedsediments and breccias 10 Vesicular basalt - horizontal 3 to 5 (obscurity due to vegetati0.n and talus).

- 48 - COMPOSITESECTION ON XYZ, SEE PLAN

SECTIONAL ELEVATION ONAB. BEARING N.23*W.. SEE PLAN

LEGEND

Sediments Cache Creek Series (in Plan) -

Sediments Cache Creek Series (in Sections) TERTIARY MINE Tertiary channel-filling, including bed-rock gravel Plan (from map 6f ownerr) Channel-filling overlying Tertiary bed-rock gravel

Post-glacial channel-filling - . . .

Buildings - - . . . . .

Fig. 5. Plan:of the Tertiary Mine. kt one point differential weatherinc has formed I). detached pillar, about G feetin diameter and 40 feet iwheigh';. This is composed of a capping of basalt 15 feet in thickness restini on 25 feet of slig.htly-inclineds-trstified sediments and breccias, which rests on lava(see ?late I B).

Tertiary Mine - Camine Channel

Thisexamination suggests that this channel, exposed on both sides of the Fraser River at the Cottonvwood Canyon and described in de-tail in British Columbia,Degartment of MinesBul.letin No. 3, 1940,pp. 22 to 27, is closelycontemporaneous with the intra- Upper 'JolcanicsFraser River (Fig. 5).

There is much tosuggest that this channel trend:; parallel to theFraser River for some considerabledistance north-west of the Tertj-aryNine workings, British ColumbiaDepartment of MinesBul- letin Xo. 3, 1940. If so, it likelyrepresents the Tertiary cutting of the down-streai part of the valley incised between the mouth of the %est Road Riverand the mouth of the Cottonwood River.This valley was incised .and drainagein the 'Jest Road River from the Tertiary mouth of this river to WhitesLanding. was reversed when the ancient valley to.the east, formerly occupied by theTertiary Fraser River up to and including the inter- volcrmicFraser River, was abandoned.This aband0nmen.t appears to havebeen due partly to the great accumulation of sediments in the ancient valley and partly to damrning of the'waters of the inter-volcanic Fraser River down-streamby eruptioil of the Upper Volcanics.

SundryAdditional Exposures

0whg to tne criteria being insufficient to determinethe age withcertainty, the following exposures are grouped separately, and are not inserted on thegeologic maps accompanying this report as indicatingdefinite channels:

(1) The verycoarse conglomerate and associated sediments exposed on RedrockCreek, 23 milessouth of Prince George (Fig. 2) anddescribed under "Bed-rockGeology," may represent a late Cretaceouschannel of theFraser River.

(2) Segments of formerchannels of theFraser Ri.ver of probableTliocene age lie buried at thefollowing points:

(a) On theeast side of the Fraser Riverimmediately up- strearn from Diamond Island, near AlexandriaFerry, a se&ment of a Fraser River channel is incisedin Aus-tralian members (a) of the Fraser River formation. The length of the segment is somewhat over a mile, but nogravel is exposed. The post-glaci;ilwaters

- 49 - having swept over the up-stream part, left an extensive bench about 10 to 12 feet above the rivar,on which the draf-line dredge of North American Goldfields Limited is operating. At the down-stream end high glacial bankswhich overlie the west rock- rim of thechannel gravel have notbeen removed by post-glacial waters and the channel filling is preserved a forlength of 333 feet and height of40 feet above river-level. This rim consists of Australian members (a) tineof Fraser River formation.

The topography very strongly suggests that the up-stream continuation of this channel-segment lies buried in the west bank of the Fraser River totiie west of Castle Rock,2 miles up-stream from the last exposure.

(b) At the lower end of Fort George Canyon.A former channel of the Fraser River is cut by the.river at the lowerof the end Fort George Canyon and the fil1ing.i.s exposeda distancefor of upwards of halfa mile between that point and the mouth of Redrock n"reek, and overa vertical height of about230 feet.

The folloxing section is here afforded: at the top, underlying soil and timber growth, silt,3 feet; post-glacial gravel3 to 7 feet; varved clay, 25feet; boulder-clay, 5 fest; cross-bedded glacial gravel, 33 feet; boulder-clay and glacial gravel,25 feet: well-sorted river-gravel, not very tightly compacted,80 feet extending to river-levsl. Some of the varves of the boulder-clay are curved indicating slunping subsequent to deposition.

The river-gravel in this exposure may represant the restoration of flow of the Fraser River subsequentdmming to by the Upper Volcanics, and may thereforebe 0-E Pli.ocene age, although it is also possible that the gravel is of interplacialage. In- sufficient criteria make the matter indeterminate. Lack of any high degree of conpacting doesnot, however, necessarily disprove Tertiary age. In the channel exposed on the north side of Baker Creek, the sediments underlyinr pillow-lava ofUpper the Volcanics, are loose.

(e) On the east bank of the Fraser River directly opposite Sout'n Fort George. The east bank rises steeply at this point to a height of 355 feet above the river. The following section is afforded: At the top overlain bysoil, veptation and timbsr- growth, varved clay,12 feet; silt, 15 feet; obscurity causedby sloughed material,62 feet; interstratified, fairly well compacted beds of fine gravel and sand with one smallof bedcompacted clay 6 inches thick, 146 feet; obscurity to river-level,120 feet,due to sloug.hed material and vegetation. The bedsof sand and pravel are horizontal. The pebbles in the gravel beds rangefrom 1/2- inch to 3 inches in diameterand imbrication indicatesa southerly flowinc stream.

- 50 - Plate I1 A. Drag-linedredge of the NorthAmerican Goldfields Ltd., FraserRiver 1 1/2 miles up- stream from Alexandria Fer1.y.

Plate I1 8. Plaoeroperation of H. Craig,Fraser River 2 miles south of Quesnel. . About 230 yardsdown-stream from the described ex,?csure a small creek hascut a dee.3 incisionin the deposi-t, and clearly reveals that the sand and gravel beds are kirectly overlain by boulder-clay. The followingsection is exposedabove ths beds of sandand gravel:at ths top,underlying soil, weetation and timber-growth,varved clay, 13 feet; silt, 20 feet;boulder-clay, 25 feet;glacial gravel, 15 feet; sandyboulder-clay, 59 feet; horizontallystratified beds of sand and finegravel, !j feet to obscurity due to sloughedmaterial and vetstation.

It seems likelythat the beds of sandand gravel are of Plioceneage representing gradual restoration of flow after damming of tine Frasergiver down-streamby the Upper Volcetnics. It is also 2ossible t'nat t'ne age of thesebeds is interglacial: criteria are insufficient to determine ag.e with certainty.

(d) On the Nechako River,directly north of PrinaeGeorge, the northern bank rises steeply to a height of 345 feet: above the river, affordin!, thefollowing section: at the top overlain by 3 feet of soil andtimber-growth; sandy limy silt, 35 feet;boulder- clay, 20 feet;thinly-bedded horizontally-stratified sand, con- tainingsmall pieces of lipite, with some finegravel beds, 60 feet;beds.of fine sand, 10 feet:obscurity to river-level due to sloughedmaterial. Criteria are insufficient to determine' whetherthe beds of sandand gravel underlying the.boulder-clay are of Pliocene or interglacialace.

- 51 - TERTIARY XEST- -. 20A.C (3LACifh'ATZR) RIVZ? SZDIXZNTS

Thesesediments are exposed on theFraser River at several pointsbetween the mouth of t!le WestRoad Riverand h%it.?s Landing. They are of distinctivecharacter because the large proportion of pebbles composed of grey-blackquartzite are somewhat iron-stained anddiffer greatly in appsarance from TertiaryFraser River sediments. The distribution of thelkst Road Riversedi.ments in the Fraser River Valley, in this region proves conclusively that the drainagein the former river has been reversed between t'ne nouth of theTertiary West Road Ziverand Whites Landing. As these sedimentsunderlie those of the inter-volcanicFraser River near !,,%itesLanding, and commingle with the latter in exposures close to this point, it is clearthat reversal was effectedafter the waters of theFraser River abandoned their inter-volcanic channel.

The largestexposure of sediments of the Tertiary blest Road River is half a mileup-stream from the mouth of the present river. The southern end of theoutcrop 'is at the western edge of the FraserRiver, but the distance of theexposure from the river increases to thenorth. Immediately north of the mouth of the West Road River, a rock-rim composed mainlyof schistose quartzite, rises sharply from the Fraser River to a height of450 feet for a distance of half a mile. The southern endof the exposure of sediments of the Tertiary WestRoad River commences at the northern endof this rim. The rim sloping at from 15 to 20 degrees with overlying sediments is ex2osed for 25 feet. Although some- whatobscured by vegetation, the sediments are exposed for a further 879 feetto the north-west. The averageheight ofexposure is about 40 feet, and thebase is about 25 feet above the level of theFraser River. The sedimentsare directly overlain by soil and consist of horizontally-stratified beds of fine andcoarse gravel,grit and sand. They aretightly compacted, theweathered facebeing almost vertical. The beds show considerableiron- stain. Although therelative thickness of the gravel, and sand beds vary from point to point, the following section is typical: At thetop, soil, 2 feet;fine gravel, (pebbles range from 1/2- inchto 3 inches in diameter), 6 feet;sand, 3 feet;coarse gravel(pebbles range from 2 to 6 inchesin diameter ), 15 feet; talusslope, 8 feet:fine gravel (pebbles range from l/2-inch to 2 inches in diameter)with coarse angular pieces of ta1u.s in sizeabout 1 foot by 1 1/2 feet at thetop, 12 feet.

Imbrication of the gravel indicates a northerly flow of water in which they weredeposited. About 60 Fercent. of the pebblesare composed of grey-blackquartzite. About 13 percent. of pebblesare composed of batholithic rock andvolcanic rocks. Quartzpebbles possibly amount to 2 percent. of thetotal. A few pebbles ofhighly-decomposed basalt are present.

- 52 - X0 opinioncan be formad as to thedepth at .gdhich thebed- rock of thischannel lies. In recent years Andrew Stewartsank txo shafts to de&iis of 40 and 73 feetrespectively in ans-ttempt toreach bed-rock and although vater was nota2parentl.y encountered theshafts were discontinued. Tne laddershave been removed and theyare not now accessible. The shaft sunk to a dept:n of 40 feet is at the-northern end of theexposure, about 1000 fee.t from the FraserRivix, and the bottom is about 20 feet below the river. .The othershaft is 140 feet north 59 degreeswest from the first andthe collar is 45 feet above it.

On the east bank of theFraser River, about 2 1/2 miles above the lnouth of the West Road River,the Tertiary sedimen-ts are exposed over a length of 500 feet andheight of 35 feet. There is little if anyglacial overlie, th'e sedimentsbeing directly covered with soil andvegetation. The topof the exposure is 100 feet above the

FraserRiver ~ The Fenera1character of theexposure of alternating beds of gravel and sand is verysimilar to that previouslyde- scribed. The imbrication of thepebbles indicates a northerly flow of the water in which they were deposited.

About 3 1/2 milesup-stream from the last-mentioned exposure on the same side of theriver, 6 feet abovewater-level. a bed or iron-stainedimbricated gravel 4 feetthick, closely resembles in appearanceand composition of pebbles,the Tertiary sediments of the WestRoad River'. The length of thisexposure is 75 feet, im- bricationindicates an easterly flow of water.0verlyi.ng this bed is anothergravel-bed 4 feet thick also, somewhat iron-,stained, butpebbles show westerlyimbrication. This latter is overlain by a total thickness of 8 feet of post-glacialgravel and silt.

On thenorthern bank of theFraser River, 5 miles~down- stream frox the mouth of Whiteslandin&Creak, 75 feet above river- level,sediments of theTertiary blest Road Riverare exposed ut three points in a distance of 150 feet. The 1arC;estindividual exposure is 25 feetlong and 10feet high. The exposures consist of beds of somewhat iron-stainadsa?d and gravel and the imbrication indicates an easterly flow of the water in which they were deposited.

An exposure of Tertiary WestRoad Riversediments underlying. sediments of the inter-volcanic Fraser River on the northern bank of theFraser River a shortdistance below Whiteslanding Creek hasbeen described under "Tertiary Fraser River Sediments."

- 53 - -TZRTIARY LACUSTRINEDEPOSITS Depositsof lacustrine type, believed to be of Tertiary age, occur atthe following points:

(1) Near i'rinoe George on thedelta-like area near the mouth of the Nechako River.

(2) On bothbanks of the FraserRiver near TaborCreek where thedeposit is somewhat over 190 feet in exposed thickness.

(3) As a valley-flooringin the valleys of Government, Hixonand TerryCreeks, (from remnants left on the valley-rims it is evident that stream erosion has removed a considerablethickness of the original deposit).

In all casss,save the first-mentioned, the deposits form a false bed-rock on which importantconcentrations of placer-gold occur inoverl.yiny poat-glacial gravel.

These depositsdiffer greatly from those lacustrine deposits of Pleistoceneage, which occur at many points close to the FraserRiver, andwhich were caused by damming due to deposition of glacial debris.

No fossils were'found in any of these deposits, and in some cases ?heoverlying material is of post-glacialage. Determina- tion ofage must rest upon the features presentod by the deposit itselfstudied inconjunction'with the known darningof the Fraser Rivarby lava in Tertiary time and its possibleeffect in origi- natingdeposits of thistype. In other cases Tertiary age is indicated by a heavyoverlie of glacial material. In some cases this type.of deposi-L is underlain, in others overlain by a de- positof apparently tumultuoustype. Such association of two radically differznt types of deposit can be explained by the reasonableassumption that at timesthe river suddenly broke throughlava-dam, causing a rapid fall of water-level in the lake first formed.

(1) Exposuresnear Trince Georgeon thePrince George- Hazelton highwayoccur (a) at a point 1 1/2 milessoutherly from the town at thesouthern base and on thesouth-western slope of the more southerly knoll mentionedunder "Topography" and (b) distant 1 1/4 miles to thesouth of (a) on the highway at the point where the lattGr ascends the southern rim of the Nechako RiverValley. (Fig. 4). (a) At thesouthern base of the more southerlyknoll on theeastern side of the highway,compacted greenish-colouredbeds of clay-grit andsand overlie conformably

- 54. - gravelscontaining angular and sub-angularpebbles whioh range from 3 to 6 inchesin diameter. Thesebeds strike n0rt.h 32 degreeseast and dip about 35 degreessouth-eastward. The pebbles of the g.rav-1-beds are composed of schistose rocks similar to those exposed at points to the north in the southern rim of the Nechako RiverValley, with a preponderance of schistose argillite. The combined total thickness of these beds varies from 10 to 20 feet, and theyare unconformably overlain by horizontally- stratified post-glacial gravels 30 feet in thickness on which rest sandbeds 3 feet in thickness cappedby 2 feet of soil and vegetation. ,The faceof the exposure is nearlyvertical, and thetotal length is 475 ?$et. It formsthe southern bank of the "Hudson Bay Slough" at this point.Distant 400 feetsoutherly from the last exposure, md 60 feet higher in elevation on the south-westernslopes of the same knoll on theeast side of the highway, a maximum ex;Josed thickness of 20 feet of beds of angular androunded deeply-kaolinized granitic pebbles ranging in diameter from 6 to 10inches are conformably overlain by a maximum exposed thicknessof 12 feet of gravel consisting of angular' and sub- angularpebbles of chicflyschistose argilli-La. This exposure, 63 feet long and of maximum height 35 feet, is directly overlain by soil and vegetation. The bedsstrike north 32 degreeseast anddip 35 degrees south-eastward. ' (b) About 1 1/4 mi:!es from the last exposure the highway ascends the southern rim of the Nechakc RiverValley. At thispoint greenish-colourad clay-grit beds underlie the road-surface, but their attitude is not apparent. About 350 yardsfarther south on theeast side of thehighway, at a pointabout 110 feet higher in elevation, is axposed a bank60 feet long and.25 feet high consisting of coarseangular andsub-angular pebbles and boulders of the same rooks a.s those found at points to the north on thesouthern rim of the Nechako RiverValley. This exposure is directlyoverlain by soil and vegetation. The pebblesand boulders of averagediameter about 10 inchesare deeply-rotted. This deposit also outcrops at several points in a distance of 200 yardsin a bank to the south- east of this point, and apparentlyunderlies a considerablearea. The attitude is indeterminate. In thecase of exposures described at points (a) and (b)the angular and sub-angularrotted gravels resemble those laid down by a torrential stream flowing for a shortperiod, and inboth cases they overlie.deposits vvhich areobviously lacustrine. The inclination of thestrata may be due to slunping rather than to tectonic movement IafLer deposition,but it is obviousthat the deep r0ttin~aandk:aoliniza- tion of the constituent pebbles must havetaken place af;er deposition, and for this reason a Tertiaryage is inferredbecause theconstituent pebbles of Pleistocenedeposits are seldomweath- ered to such a degree.

(2) On bothsides of theFraser River near the mouth ofTabor Creek.

- 55 - In this region on the east side of the river and on an average of 103 feet above it, a lacustrinedeposit is exposed almost continuously for a length of 2 milesfrom 1 mile above to 1 milebelow TaborCreek. On thewest side of theriver, directly opposite, the deposit is exposed in three places in a length of 1 l/4miles from a pointopposite 1 mileabove Tabor Creek. The largestexposure is opposite TaborCreek, which, 'with the overlie, rises steeplyfrom the river for a lengthof several hundred feet and reaches a height of 235 feet above theriver. Otherexposures on thisside are much smaller.

The characterof the deposit differs somewhat on the tivo sides of theriver. On theeast side, it consists of somewhat over 100 feet of interstratifiedbeds of arkosic grits, gritty clays, and gravalwith pebbles ranging fron 1/2 inch to 2 inches in diameter. Thesebeds are horizontal, and areoverlain by 1 foot to 14 feet of post-glacialgravel with numerous largeboulders, and underlain at river-level by greenish-colouredclay beds. The post-glacial gravels contain an important concentration of placer-gold.

On thewest bank of the Fraser River opposite a point 1 mile northof TaborCreek horizontally-stratified beds of arkosic grit andclayey grit, of a total thickness of 65 feet,extending along the river's edge for a distance of 125feet, are overlain by 4 feet of post-glacialgravels. Immediately down-stream from this pointthese beds are unconformably underlain by greenish-ooloured well-lithifiedbeds of clay,strike north 47 degreeswest, dip 25 deEreessouth-westward. Directly opposite TaborCreek on the westside of the river, a thickness of 110 feet of well-lithified greenish-cobouredclayey grit beds is overlainunconformably by 75 feet of cross-beddedglacial gravel. The latter is overlain by a considerable amount of silt, which apparentlyreaches a depth of 40 feet.at one point. A thicknessof 10 feet of.varved clay is overlain byshallow post-glacial gravel and silt at the top of the bank. The totalheight of this bank is 235 feet, and althcughthe face is obscured somewhat by sloughing,the order of succession and thickness of the various beds are approximately as givenabove. The greenish-colouredclayey grit beds dipabout 25 degrees or more westward,but the exact dip andstrike areobscured bysloughing.

On theeast side of the river the discharge from thesluice- flume in placer-mining olerations has 'thoroughly washed tine near- vertical face of thedeposit at several points down-streamfrom TaborCreek, and exposures are particularly clear. The followine: section at a point three-eights of a milebelow TaborCreek is typical,(except for the thickness of Tost-glacialcrave1 which varies from point to point); a-t the top, overlain by a fewinches sf soil andvegetation, post-glacial auriferous gravel, 1 foot; alternating -thin beds of coarse and fine arkosic grit andclayey grits, 30 feet(the particles, which areangular or sub-angular,

- 56 - inthe coarser grits average about l/4-inch in dianeter);beds of rounded,and sub-angular gravel, 25 feet (some pebblesreach 2 inchesin d;.ameter, the average size is about 1 inch in diameter but a few graniticpebbles are present up to 15inches in diameter, withlenses of clayey grits); fine grit beds interstratified with beds of clayeygrits, 37 feet(large pieces of lignitized driftwood occurin the lowest 10 feet of thesebeds); oxidized arkosic grits,extending to river-level 20 feet. At river-levelbeds of g.reenish-colouredgritty clay are exposed. The lowermost clay was probably laid down in a lake whereas the gritty rnaterial may repre- sentshore-line deposition in the same basin.

TaborCreek which joinsthe Fraser River at grade has cut down through the top of thelacustrine de2osit. The farthest ob- servedup-strean exposure of the latter (30 feethigh, 25 feet long),occurs on thesouthern bank of t'ne creekabout half a mile above its mouth. On thenorthern bankof thecreek near the mouth is an exposure of the lacustrinedeposit, 100 feet high,and 175 feet long. A section of thisfollows: At the top, post-glacial graveland si1.t cappedwith vegetation and timber-growth 3 to 10 feet;thinly-bedded slightly oxidized arkosic grits 80 feet; bluish-colouredclayey grits andclnys down tocreek-lsvel, 20 fee-t.These beds are horizontal.

On thesouthern bank opposite,an exposure 75 feetlong reveals a thickness of 7 feet of thelowest members of tile same beds in contact with 4 feet of well-lithified greenish-coloured clay (very similar to those described on the west bank of the Fraser River opposite this point and near Prince George); overlying,this exposure is 13feet of post-glacialgravel and silt. Considerable faulting is evident in thegreenish-coloured clay, which has also affected to a lesserextent the lowest members of theoverlying deposit. These greenish-coloured clay beds are also exposed on theeast sideof the river just abovewater-level at several points down-stream from the mouth of Tabor Creek, and i-t is clear thatthey underlie the other deposits described on this side of the river.

Theseexposures indicate that after-the greenish-coloured clays and thelowest beds of the overlying clayey grit:; were depositedthey were tilted either by faulting or slumphg. Then followeddeposition of theoverlying horizontal beds of' clayey crits, gravel and arkosicgrit. Tho attitude ofwhich indicates theabsence of movement subsequent totheir deposition. Their charactercoupled with presence of pieces of carbonizeddriftwood, demonstratesthat lacustrine conditions alternated with those of sluggishflow of water. On theeast side of tieriver post- glacial erosion has entirely removed anyonce existent overlying glacialdeposits such as those on thewest side of the river, and thelacustrine deposit is directlyoverlain by auriferousgravel

- 57 - containing numerous boulders, many of largesize (the dimensions ofthe largest observed boulder were 5 1/2 by 3 1/2 by 3 1/2 feet. The depthof -the overlying post-glacial gravel varies from 1 footto a maximum of 14 feet. !in importantconcentration of placergold has been laid down on topof the impervious lacustrine deposit.

A carefulexamination of the boulders was made in order to determinetheir source, and the matter is furtherdiscussed sub- sequentlyunder "Placer-gold Deposits." Tossibly there has been a comminglingof drift fromseveral sources (a) From the.north- westby an ice-sheet which moved south-easterly (b) From the north-east by an ice-sheet moving south-westerlyfrom the Rocky Mountains.

Fieldobservations indicate that thegeneral features of this deposit are radically different from those of Pleistocenelacus- trinedeposits and more nearlyresemble those of Tertiaryage. It appears to trend in a north-westerlydirection, and the underlying tilted greenish-coloured, clay beds are similar to those previously describednear Prince George. Both deposits may havebeen laid down in thesane lake or in two closely-adjoininglakes.

(3) On Government Creek.Placer deposits on thiscreek occur on a false bed-rockformed by a deposit of lacustrine type with which apparently the valley is floored for a distance of about one mileabove the canyon.

The thickness of this deposit is unknown and theonly information.nowavailable concerning i-t, is fromexposures only a few feet high at wide-separatedpoints on thebanks of thecreek and from shallowshafts sunk in it at various points, some of whichhave now caved. About 1 mileabove the canyon, the low-lying benches on the creek are underlain bycompacted thinly-bedded clay-silt. The latter, as shown by the dump at the collar of a shallowshaft now full ofwater, is apparentlyunderlain by angularand sub- angularpieces of quartzranging from 1/2 inch to 2 inches in diameter mixed wi-th an6uls.rand sub-angular pieces of schistose rocks ofabout the sane size. Similar rocks occur in place within the valley at up-stream points.

Near the head of the canyon on eachside of the creek, within 10feet of thewater's edge, four shafts havebeen sunk opposite eachother at intervals ofbetween 35 and 40 feet, on small low- lying,benches which flank the creek at this point. As thecreek flows overbed-rock quite possibly bed-rock was reached in all ofthe shafts. Those on thewest side of thecreek are filled withwater, to within 10 feet of thecollar. The materialpassed through in eachcase consisted of thinly-beddedtight sand, clay, and fineacplar and sub-angular material with some quartz. Huch

- 58 - the same material was encountered in the shafts on the east bank of the creek,as far as can be judged from their sloughed condi- tion, save that in the most southerly, below the lacustrine beds, a bed of coarse sub-angular quartz pebbles was cut. This bed is directly underlain by bed-rook. The quartz pebbles range from6 to 10 inches in diameter.

(4) On Hixon Creek. Exposures of deposits of lacustrine type occur on Placer-mining Lease No. 2118, held by E. Hann and J. Strbac, about 1 1/4 miles from the old camp of Quesnelle Quartz Mining Company Limited.

R branch-road 4 1/2 miles long, leaves the Prince George- Quesnel highway, a short distance northof Canyon Creek, and leads to the propertyof Quesnelle Quartz Mining Company, Limited. From this point the propertyis best reachedby following the wagon road to Little Rixon Creek, and thence along tie flume-gradeof Exon Guesnelle Tlacers, Limited,on the north side of:Llixon Creek.

Hixcn Creek in this region flows north-westerly and westerly. The placer-Norkings of the formof a shallow hydraulic pitof maximum depth 20 feet, are on the south sideof tie creek, and extend for 450 feet along it, and to a maximum distance of375 feet south of the creek. These vuor!cings follow boulderypost- glacial gravel, several feet thick, which overliesa false bed- rock, described below, ator near creek-level. The post-glacial gravel contains coarse ,placer-gold of residual character. The elevation of the floor of the pit, which is but littleibove creek-level, is 2480 feet.

Up-stream and down-stream fromtine hydraulic pit, schistose rocks are exposed at intervals 30th on sides of the creek at creek-level. Farther up-stream granitic rocks are knownto occur. Underlying the post-glacial gravelis a false bed-rock consisting of white clay in which are angular and rounded frag.- ments ranging from 1/8-inch to several inches in diameter. These constituents. consis-t of high-temperature bluish-coloured quartz, vein-quartz, schist,and granitic rock; some are extensively kaolinized. The thickness of this material is unknown. A fine-Erained, thinlybedded deposit of a salmon-pink colcur direotly overlain with soilor shallow veneer of glacial debris, is exposed at the western edgeor" the hydraulic pit fora dis- tancs of 200 feet and maximum height 20of feet. Under the hand-lens this salmon-pink coloured deposit is seen to consis-t cf quartz and rock-particles with abundant sericitic material. Ferruginous bandsup to 1-inch in width occur at several points. Underlying this deposit there appears toa considerablebe amount of lignitized wood, but owing to sloughing this was not claar. This lignitized wood presumably occurs at some points between the salmon-pink deposit and the kaolinized false bed-

- 59 - rock,but at others the salmon-pinkthinly-bedded deposit directly overliesthe latter, according to information supplied by the ovmers of thelease. Some years'ago two shafts weresunk in the hydraulicpit about 200 feet.apart a shortdistance south of the creek. The more westerly one was sunk 14 feetin the salmon-pink coloureddeposit bottoming in the white,kaolinized, false bed-. rock. The other shaft was sunk it is stated to a depthof 37 feet, and at a depth of 20 feetpenetrated the white, kaolinized, falsebed-rock, in which the shaft was continued for theremaining di stancl.

About 1000 feet down-streamfrom the hydraulic pit on the oppositeside of thecreek is aninformative exposure resulting solelyfrom natural agencies. The bankof thecreek is steep, sloping at from 35 to 40degrees, and thefollowing section is exposed: at the top immediately overlain by soil and vegetation boulder-clay, 35 feet:clayey silt, 2 feet;fine andcoarse sand, 1 foot:arkosic grit, with rounded and angularparticles of quartz and feldspar, andcontaining considerable mica, 6 ,feet(the lowest part of this bedcontains some salmoc-pinkcoloured material); thinly-boddedsalmon-pink coloured deposit, identical. in character with that describedin the hydraulic Tit, 29 feet; sloughedmaterial 45 feet, which obscuresthe base of thesalmon-pink coloured deposit,extends to creek-level. The attitudeof all bedsbelow .theboulder-clay is horizontal. The totalthickness of boulder- clay is quite likely much greaterthan 35 feet, as the top of the valley-rim is about100 feet above this exposure, and covered withvegetation and timber-growth. This exposure proves that thedeeply oxidized salmon-pink coloured deposit is of Tertiary ags, as it is altogetherimprobable that oxidation could have takenplace subsequent to the deposition of theheavy cover ap- parentin .the section.

The kaolinized white fragmental material which underlies the salmon-pinkcoloured deposit, save where the latter has been swept offby post-glacial waters, and which forms the false bed- rock on which a concentrationof placer-cold occurs, somewhat resemblss a tumultuous streamdeposit. It certainlycontains some placer-goldin its upperpart. This gold may havebeen deposited with the formation or it may have originated from the overlyingcoarse bouldery post-glacial g.ravel. Tie post-glacial gravelcontains many largepebbles and boulders of the samecom- position as the constituents of thekaolinized false bed-rock, andmight possibly result from erosion of it by a powerfulstream. Unfortunately,only the top of thefalse bed-rock can be examined, no sectionbeing exposed. It is possiblethat the salmon-pink coloured,stratified deposit and underlying vqhite kaolinized falsebed-rock occur at other points on EixonCreek down-stream, butthe deep weathering and kaolinization of rock-exposures coupled wiYn obscurity due to vegetation leave a factor of

- 60 - uncertainty. Forexample, about half a mile down-stream from the hydraulic pit on .thenorthern bank of the creek, a shai't was .sunk' in 1927 to a depthof 53 feet in a salmon-pink coloweddeposit, and at this dep-th is reported to have penetrated auriferous white kaolinized fragmental material.

(5) on TerryCreek. On this creekconcentration:; of placer- goldoccur at different points of thecreek in post-glacial gravel a few feet thick overlying a false bed-rock of kaolinized granitic material which contains many large roundedboulders of quartz. At the date of examination on September 14thArchie Stewart and as- sociates at a pointabout 1 1/2.miles above the mouth of thecreek wereengaged inshovelling post-glacial g.rave1,overlying the kaolinizedgranitic material, into a sluice-flume. The post- glacial gravels here are several feet thick and form the low- lying banks of thecreek. Discovery of a three-ouncegold nugget was reported in 1940 by Stewart.

Just below.the junction of Tom Creek, a small tributary flow- ingnortherly into Terry Creek 4 miles.above its mouth, on the steepsouthern bank of TerryCreek, a particularly informative section is afforded: at thetop, overlain by veeetation and timber-powth,boulder-clay and glacialgravel, 50 feet;red- stainedsand and gravel (stated to contain some placer-gold) 25 feet;stra'Lified clay, 5 feet;boulder-clay, 35 feet;kaolinized materialconsisting of sub-angularand rounded boulders of quartz,quart.z-feldspar (some 2 or more feetin diameter ), and graniticrock, 35 feet, ex.tending to creek-level.

A shor-tdistance up-stream, from this point on the same sideof the creek, immediately above Tom Creek,the following section is exposed;-at the top overlain by vegetation and timber- growth,boulder-clay 30 feet;kaolinized fragmental gra:nitic material vvithlarge boulders, 25 feet. The fragmentalgranitic material overliesgreenish-coloured clay beds atcreek-level.. The greenish-colouredclay is similarto that describedas occurring nearPrince George, and on theFraser River near Tabor Creek. The kaolinizedfragmental p-anitic material has points of resem- blanoe to the white kaolinized material described on Hixon Creek. The exposures on TerryCreek prove the Tertiary age of the kaolinized frapental granitic material andof the underlying greenish-colouredclay. The formerappears to be a tumultuous strearndeposit and the latter is of lacustrineorigin. The exposureof two sheets of boulder-clayseparated by therod-coloured sandand gravel beds is of interest as proving two advances of ice. The 'interglacial aee of theslightly auriferous red-stained sand andgravel beds is alsoclearly indicated. It is possiblethat the placer deposits on this part.of the creek result in' part from the re-sorting of thered sand and gravel by post-glacid waters.

- 61 - PLACER-GOLDDEPOSITS

LEASES W THE Five placer-mining leases held by the FKX?ZRTSON S20TIlZRS Robertson&others, of FrinceGeorge, are on the east bankof tie Fraser River imme- diatelyto the south of Tabor Creek. In 1940 N. G. Thomas held a workingagreement on this ground.

The property is reached bji a branchmotor-road, 4.2 miles in length, which leavesthe Prince George-Quesnel highway inmediately southof the TaborCreek crossing 13 milessouth of Prince George. The roadleads almost due west across to the western edgeof the plateau,then crossing the Pacific Great Zastern railway-grade descends on good grade to a large bench on which the property is situated.

The propertycovers the greater part of a large triangular- shaped,well-timbered bench situated about 105 feet above the FraserRiver. This bsmh ?having a totalarea of about 375 acres is bounded, on the north by thesouth valley-rim of TaborCreek, on the west by the Fraser River and on the east very nearly by thePacific Great Eastern railway-grade, save that thebench extends to theeast of it in thevicinity of TaborCreek. There are variousshallow depressions in thebench due to the differential cutting'of post-glacial waters such as frequentljroccur on large benches;chisf of these depressions is one abouthalf a milelong of a maximum depth of 25 feet, which crossesthe bench obliquely to theFraser River abowt a nile below the mouth ofTabor Creek.

Tfle placer deposit is a concentrationby post-glacial viaters in boulderygravel which varies from 1 foot to 14 feet in thickness andimmediately overlies a falsebed-rock formed by a tightly-compactedimpervious lacustrine deposit (see Lacustrine Deposits)which is of unknown thickness but which is exposed at %heedge of the bench for a height of 105 fee% above river-level. Huch of thegold is coarseand nuggety although some is fine.

The existence of thisdeposit has long been known and the lower part of TaborCreek, which cuts the deposit to a depth of some-what over103 feet, was 2ossibly workedby the early miners. in 1925, 8 mineralclaims named SixMile Goldfields group, were staked at t'nispoint, owing to the reportedoccurrence of gold values in the lacustrine deposit as distinct froa the placer-gold in theoverlying gravel. in 1932, Prince GeorgeGold Mines, Limited, was incorporatedand acquired both placer-aining and lode-mineralrights near the mouth of TaborCreek, but no material activity resulted (see knnual Reports of Minister of Mines, British Columbia,1925 and 1932).

In 1934, E. P. Caus and 3. Vulsonacquired thrae placer-

- 62 - miningleases on the bench to the south ofTabor Creek, and in- stalled a pump at river-level to deliver wash-water to the bench. They reportedencouraging values, but subsequently discontinued operations.

In 1039 J. S. Robertsonand Tal Xitt tested the btanch farther to the south than previoasoperators, reporting good vtrlues in the region workedby N. G. Thomas in 1940. A high-lying beanch such as exists at this property offers a difficulty to thesmall operator, if no readily available supply ofwater can be broue;ht to the groundby gravity.

In 1939 I\[. G. Thornas broughtwater on theground from the upperpart ofTabor Creek,installing a flume 24 inches by 15 inchesabout 1 1/2 milesin length, for thispurpose. N. G. Thomas statedthat after sinking forty-two test-pits over an area of.50 acres, hedecided to instalmechanical equipment,.

The gravel was loade?,by a shovelwith 5/8-cubic yard bucket operated by a gascline.engine,into motor-trucks, whichconveyed it to a washint-binset upover a sluice-flume at theedge of the bench. Grizzly barsover the bin werespaced at i.ntervals of 5 inches, and the washed oversize ivent tothe waste dump at the river's edge,.the underside passing into the sluice-flume.. At thetime of examinationthree motor-trucks were employi:d, con- veyingan estirnated 3 cubicyards of gravelper load, the total maximum amount of gravel trucked in a shift of 8 hours being about 360 cubicyards.

The water-flumebringing the water supply is at the northern end of theground, and the gravel is removed inlong narrow sections from the edge of thebench easterly. Themany large bod- ders are piled in rows parallel to the edgeof the benohand so spaaod that there is room for a truok-roadbetween any two rows. At thetime of examination in 1940an area about 750 feet by 350 feet near the northern end of the benchhad bem mined.

The sluice-flumein use was 67 feetlong, cross-sectional dimensionsbeing 2 1/2 feet by 1 foot 4 inches.Riffles used in the first 54 feet of theflume consisted of rails laid both longi- tudinally andcross-wise directly on the.bottom of theflume, but in the central part of the flume the rail riffles were laid on metalscreenin?. over blanke.t-clo.th. Below the rail riffles a lengtn of 6 feet consisted of rubber-riffledcloth. At the end of the latter was anunder-ourren-t in which riffling consisted of expandedmetal on blanket-cloth.

The lacustrinedeposit formine; the false bed-rock is quite impervious,and for this reason in wetweather, the collection of pools of water on the clayey false bed-rock either retards or

- 63 - entirely prevents the operation of the motor trucks.,

Al-though there is some finegold, much of it is coarseand nuggetyand easily recoverable; pieces up to severaldollars in value,ivith one nug.get weighing 6 dwt., werefound. Occasional small nuggets of nativesilver and nativecopper are recovered.

Values are stated to vary from point to point, andalthough theaverage value per cubic yard is not known to the writer, de- tailedtesting of a largearea in this region seems warranted. It is not known if theentire bench is underlain by the lacustrine false bed-rock, but both bench and false bed-rock continue beyond the limits of this property for about 1 nile to the north of Tabor Creek. The benchcontinues for about 1 1/2 milessouth of Tabor Creek,and the edge of thelacustrine deposit is exposed at the river to a pointabout 1 milesouth of TaborCreek beyond which the edge is screenedwith dense vegetation. The lacustrine deposit is exposedover a height of 30 feet andlength of 25 feet on the southern bank of TaborCreek about half a mileup-stream from the mouth. This is thefarthest observed easterly extension of this deposit.

LEASE OF P. 1.1. XUUNRO OI!e placer-mininglease held by P. W. Munro of Trince George immediately ad- joins the property of theRobertson Brothers on the north, and extends for half a mileup-stream .?om the mouth ofTabor Creek coveringground on bothbanks of thiscreek. The property is reachedby a branchmotor-road 400 yards long from the road lead- ing to the property of the Robertson Brothers.

The part of the property now being worked by the owner ic, close to the boundary line be-tween his proper-ty and that of the RobertsonBrothers, and is thenortherly continuation of the same bench. The type of placeroccurrence is the same in both p-operties at this po'int.

By arrangement, P. N. Munro usespart of thewater-supply fromthe flurne andworks his property byhand, shovelling the gravel into a small sluice-box. The size of thehydraulic pit at thetime of exaxination on July loth, was about 100 feet by 50 feet. On this g.round~thedepth of post-glacialmaterial overlying the lacustrine'deposit forming the false bed-rock was about 4 feet, of which thelower 15 inchesconsisted of gravel,and the upper 33 inches of silt. The owner reportsencouraging values. The characterof the g.old is much the sme as that recoveredfrom the Rober-tson leases.

LEASE OF A. DRAGE One lease, No. 4044, it is understoodad- joins that of P. !,!. Munro to theeast. On July lotin, 134'2, no sluicingoperations were takingplace, work tothat date having comprised general prospecting.

- 64 - A careful examination was made of t'ne boulders in the auriferous gravel, and also of thegravel beds in the lacustrine deposit It seems evidentthat there may becommingling of glacial drift in thisreg,ion derived from several sources: (a) From thenorth-west by anice-sheet moving south-easterly,(b) From thenorth-east by an ice-sheet moving south-westerly.

Zxaminationof the Xobertson Brotkrs hydraulic p.it showed that about three-fifths of the boulders were composed of foliated quartzites,about.one-fifth were batholithicrocks, andabout one- fifth werevolcanic flow rocks probably of Palaeozoicage. A few quartzboulders were observed. The largestobserved boulder was 5 1/2 by 3 1/2 by 3 1/2 feet in size.

In P. W. flunro's much smallerhydraulic pit, about: 40 per cent. of boulders were composed ofgneissic rocks, 40 percent. were composed of batholithic rocks, and theremainder of chiefly metaqorphosedvolcanic flow-rocks.

I__General In the post-glacial gravel are some pebbles of pyrite. Two unusualtypes of pebbles wereobserved. One typeconsists of a hard fine-grained core of indurated clay in which are embedded smallerpebbles about l/Z-inch to' 1 inchin diameter. The derivation of this type was found in thecourse' o.E examination of theFraser River st upstreampoints. As previouslyexplained, deposits ofvarved clay occur at a number of points overlying the glacialdeposits. A piece of claybreakiq away rolls down the talus slope below thevarved clay and in its passage smjdl pebbles become embedded in it. Many of thesepebbles become baked hard in the sun to besubsequently transported down-'streamby a rise of theriver. Ano-ther type of pebbleconsists of :iwhite clay interior in v~?ic?!is a smallpiece of lignite, with a Hard shellexterior formed of ferricoxide. These are alsoprobably derived from varved clay containing vegetable matter, which has beenbaked in the sun, and subsequentlybeen imprepated with surfacewaters containing iron in solution. The reducingaction of the lignite decolourizes the clay in its vicinity.

Stocks of batholithicrock of considerablesize occur (see "Bed-rockGeology") both to the corth-west on the southern rim of the Nechako RiverValley near i'rinceGeorge, and also to the north- eastnear Eaglet Lake. Smaller stocks of batholithicrock are found on themountain kno-wn locally as "Six-MileFlountain" east of TaborLake. metamorphosed volcanicflow-rocks outcrop both to the north-westand to Yne north-east of thisregion. Gneissic rocks occur in greatest abundance to the north-east at the north point of the Frnser River,although some are seento the north-west.

A number of cupriferousquartz veins occur on "Six-Hile Nountain"and adjacent region, and the placer deposits, on Skaret Creek also in thisrec,ion, doubtless have a localsource.

- 65 - &uartz veins also ocourwest of Prince George on the southern rim of the Nechako RiverValley and also in an area 5 milessouth- westerly from Prince George.

The-lacus,trine deposit itself was sampled at the eastern part of the benchimmediately east of TaborCreek, where theoverlying post-glacial gravel was known to have been particularly productive. At this pointthe upper beds consist of arlrosio grit. A smple of a vertical section 10 feet high, the top of which was 4 feet below thetop of thelacustrine deposit, assayed: Gold, nil. Another sample of the same section weiEhing 15 pounds was carefullypanned, yieldingpannings weighing one ounce. This assayed: Gold, trace; sulphur,trace.

As explainedunder “Lacustrine Deposits” in this report, the interstratification of beds of gravelcontaining rounded andsub- angular pebbles with clay and grit beds in the lacustrine deposit, indicatesthat lacustrine conditions alternated with thoseof sluggishflow. Six pebbles taken at random from a gravelbed 8 feet thick 40 feet below the top of the deposit below the placer workings on the RobertsonBrothers leases werefound to be composed of tiie following rooks: granodiorite,diorite, argillite (2 pebbles),schistose rock, chloritized andesite. These rocksare known to outcrop to the westof Prince George, on thesouthern rim of the Nechako RiverValley near which is also another lacustrinedeposit. Although thedeposit near TaborCreek appears to trend in the direction of the latter, it cannotbe assumed that both are parts of the same depositas the distance between the exposures is about 5 miles.

n,lne precise orie;in of theplacer gold in the TaborCreek deposits is noteasy to determine. The region at theheadwaters ofTabor Creek is capableof supplying the metals found, namely nativesilver, native copper andGold and perhaps is the most likelysource. The presenceof the two former,and the coarse gold indicates an origin in Tertiarytime through the operation of processes ofsecondary enrichment. Assuming a tumultuous run-offof water during the earlystages ofice-advance, it is conoeivablethat tine material containing the detrital metals mighthave been borne to its presentposition to be subsequently re-sortedby post-glacial waters. Another tenable view is that this material was ice-bornefrom its sourceto its presantposi- tion andsubsequently re-sorted. In this connection on thewest bankof theFraser River at the F0r.i; feorge Canyon, where the rocksafford no evidenceof a localsource of eold,post-glacial gravels,overlie rock-benches, and in th.3 aggregateare probably notvery rich, the gold is of coarsecharacter, onenugget weighing 3 ouncesbeing recovered some years ago (refer to Annual Report,Tlinister.of flines, British Columbia, 1935, pg. C21 and C22).

- 66 - k less likely view is that the placer-'gold orieinates fro3 a strean-erodedpart of thelacustrine deposit. Justification for such a view may perhaps be found in deposits of a tumultuous characterapparently auriferous overlyinA -1acus.trine deposits such as are described on Eixonand Terry Creeks.

- 67 - R2VI2N OF DRAINAGE-HISTORY"

AS stated in British ColwnbiaDepartment of Mines Bulletin Xo. 3, 1943, it is postulated that inlate Cretaceous time a pre- volcanic Praser River and tributaries flowed northerly north of tieChilcotin River. Tie evidence in support of this, although strong, is indirect.This northerly drainage was ultimatelyinto the Cretaceous basin which covered the region now occupied by the GreatPlains and extended to the side of the Rocky Mountains.

kihether this northarly drainage was entirely tributary to the ancestral PeaceRiver or not,must be deemed in a measure conjectural in view of tine ixxense time-interval which has elapsed. There is, however, a sub-stratum of fact whichremoves muoh from the realm of conjecture. An examinationof these factssupports the view that the major part of the northerly drainage may have been tributary to a then northeasterly-flowing Berrick-McGregor River, a minor partonly draining to the Peace River, for the following reasons:

(a) The size of the valleycontaining the Herrick-McGregor River; its low gradient and extent for about 50 miles in a north- easterly direction on the northern side of the Rocky Mountain Trench, are features suggesting that the flow of the river was originally north-easterly.

(b) The presence of a stock in thenorthern wall of the Rocky MountainTrench to the south-east of theMcGregor-River suggeststhe possible pre-Laranide age of the Trenchand possibly two paralleltrenches to the north at thispoint. Inasmuch as commencemnt of a trellis-type of drainageand deepening of the trenches would at once follow origination of these parallel mountain-structures,this suggests that the Herrick-McGregor drainageantedates the Laramide revolution.

(c) The presence of theEaglet Lake - AlezaLake - Eansard Lake Valley extending to the west virtually in line with the Herris!<-McGregor Valley, and the position of both valleys at .the northernends of thesix parallel, closely-spaced northwesterly- trendingmountain ranges, suggests that the same northeasterly- flowingriver may haveoccupied both the valleys. The subsequent reversal of drainagehas doubtless caused the mouth of the McGregor River to shift somewhat to the north of its original position,

(d) The fact that the Crooked-Pack River Valley gets shallower to thesouth and finally merges in the Nechako Plateau at Summit Lake may signify that thesource of these rivers was never far south of this point. The drift-covered Kechako Plateau betweenPrince George and Sumit Lake is to a greatextent topo-

- 68 - graphicallyPsatureless, save .ror thevalley of the Salmon River, and affords no evidence of anyformer northerly-Plowing water- course souYn of Sumi-bLake.

It, therefore, seems a rational hypothesisthat the northerly drainage of theFraser River joined by the Nechako and Salmon Rivers near Shelley was by way of the Saclet Lake - AlezaLake - Hansard Lake Valley to the then northeasterly-flowing Berrick- McGregor iiivar. A conspicuousvalley now occupiedby TaborLake and TsadestsaCreek trends north-easterly between TaborLake and the !iillowRiver Valley. This valley may havebeen occupied by the northerly-flowing Fraser River upstream from the Zaglet Lake - AlezaLake - Hansard Lake Valley. The latter is of more mature relief andappears to be olderthan thatoccupied by the Fraser River at its most northerly point, and when it was occupied by thenorth-easterly drainage there was, presumably, no through- valley where thegreat bend of theFraser River now is. Tay Creekprobably represents the headwaters of a then scutheasterly- flowing tributary of the drainage via the Herrick-XcGrogor Valley. There was also atthis time probably a northwesterly- flowingtributary drainage occupying the Rocky EountainTrench for some distbnceabove the mouth of the iierric%-McGreg;or River. Subsequently,following the Laramide revolution and the uplift of theland surface the rapid headward erosionof the then southerly-flowingFraser River being so-newhat to the west of thenortherly drainage, caused abandorment of theSaglet Lake - .AlezaLake - HansardLake Valley, much stream-reversaland, the adoption of thevalley now followed. The fact tha-t thesoutherly- flowingpre-volcanic Fraser River followed a course somewhat to thewest of that of the northerly-flowing river may perhapsbe explained by the fact that thewestern slope of the pre-existent mountain-structures which trend north or north-tiest would be calculated to havesuch effect.

The fact that thereare two exposuresof sediments of the inter-voloanic Fraser River in the great bend of the river at its most northerly point, proves the adoption of this valle:y in pre- Miocene time.

The Willow River being imprisoned in a trench was thus inde- pendent of the remaining northerly Fraser Riverdrainage, and may havecontinued to flow throughthe Eaglet Lake - AlezaLake - HansardLake Vall.ey for some considerable timeafter reversal of theremaining Fraser River northerly drainage. This may ac- countfor the erosion of theEaglet Lake - Aleza Lake - Hansard Lake Valley to somewhat greaterdepth than the TaborLake - Tsadestsa Creek Valley. The Willow River was presumblycaptured by a then westerly and north-westerly flowing tributary of the southerly-flowingFraser River. These tributariescoincided in direction with Yay Creekand the lower few miles of the Willow River.

- 69 - It will be noter! that the Bowron River makes anabrupt easterly turn and for the last 15 miles of its lengthflows approximately parallel to the Zaglet Lake - AlezaLake - Eansard Lake Valley.

It is probable tiat capture of its headwaters by the pre- volcanic southerly-flowing Fraser River would deprivethe Herrick- MoGregor River of power to hold its own againstthe slowly-rising Rocky Mountains,whereas the Peace River supplied by powerful tributaries retained a curficient volume of' .water to hold its course against the slowmountain-building.

I-t is unfortunatethat palaeontologioal evidenoe of age is lacking in thecase of thepre-volcanic exposures of river- sedimentsto the north-east of Shelley,and also unfortunate that a section is not exposednearer bed-rock be,cause of the information it would yield as tothe terrain eroded. The significance of this exposure has been previously discussed in de.tail under"Tertiary Fraser River Sediments."

The depth of entrenchment at thispoint suggests -that it may bean exposure of a southerly-flowingriver.

To thesouth the northerly-flowing Fraser River appears to haveoccupied the channel extending northward from SodaCreek on the east side of theFraser River to the mouth of Canyon Creek (Fig. 1, British ColunbiaGepartment of Mines Bulletin No. 3, 1940).Although evidence on this point is meagre, it is sig- nificant that there is a gap in the bed-rock on the Cottonwood River, 1 1/2 mileswide, in line with Dragonand Ten Mile Lakes. Elsewherethe Cottonwood River is wholly contained in a rockcan- yon inthis region. North of Ten File Lake,the northerly-flowing river musthave occupied the same valley as the pre-volcanic southerly-flowingFraser iliver, which, save for a shortcoincidence north of WhitesLanding, again joins the Fraser River Valley near :he southend of Woodpecker Island.

Schofieldin "The Origin of the Rocky MountainTrench, B.C.," Proceedingsand Transactions of the Royal Society of Canada,Third Series, Volume XIV, Section IV, 1920,considers that theproto- KootenayRiver eroding headxard captured the Nechako-Salmon-Fraser Riversdraining into the Peace River, and that these headwaters of theproto-hootenay River were subsequentlycaptured by the southerly- flowing Fraser River.

The damning. of thesoutherly-flowing Fraser River by the eruption of the Lower Lavas is discussed in detail in British ColumbiaDepartment of Mines Bulletin No. 3, 1940.Evidence was foundduring the field-work of 1940 that the Chilako and Neohako Riverswere also dammed by these lavas.

- 70 - The height to.which the Fraser River rcse as a result of dam- mingby the Lower Lavasand theconsequent depth of the basins formed in which Aus-tralian members (a) of theFraser R.iverforma- tion(the coal series) were deposited, is wellillustrated at "Rich Bar" 4 miles down-streamfrom 'auesnel on the east bank of theFraser River. T'nere a bench about 15 feet above river-level, between 250 and 300 feet wide, flanks the east bank of the Fraser River for a length of abouthalf a mile. At the back of this bsnch the valley-rim rises steeply to a height of 500 feet above the river and appears to consistlargely of Australian members (a) of theFraser River formation. The latteralso floor the bench andform the bed-rock of the post-glacial deposits of placer-g,cld at thispoint. The oldworkings cover a large part of thearea or' this benoh. '

iluring1940 atseveral different points exposures of coarse river-gravel werefound conformably overlying Australian members (a) of theFraser River formation. These are descri'o3dunder "TertiaryFraser River Sediments," and prove that in these instances flow of the r"raser.River was restored direc-tly over the basins in which thedeposits of ligni-te wereformed, doubtless as theriver cut through lava dams. They are somewhat younger than thesediments of theintra-Lwer Lavas Fraser 'River, bc!t toavoid undue complexity they have not been classified separately.

Followingdeposition of Australian members (a) of the Fraser Riverformation, orogenic movement tookplace and'tne formation was folded.

Exposures of theinter-volcanic Fraser River prova that tie life of this river was long, its headwatersextending at any rate as far as Tete Jaune, and its channel was incised to or below the presentlevel of the Fraser River. ii verylarge amount ofr erosion was accomplished by it.

Zruption of Cne Upper Volcanicswith Consequent damming again causedthe waters of the Fraser River to rise to a greal;height, as shown by exposures of thesedirnents of theintra-upper Vol-. canicsFraser River close to the top of thepresent Fraser Valley- rims. As a resul-l;of this damming, lacustrinedeposits were formed in tributary valleys, and also in the Fraser Hiver Valley near Tabor Cree:?. These depositsare described in detai.1under "Tertiary Lacustrine ileposits."

Possiblydue, indirec.tly, to damning by the Upper Volcanics down-stream, the Fraser River at this time abandoned its former valley,largely filled with an accumulation of sediments,between WhitesLanding and the mouth of the Cottonwood River, and incised a new valley between the nouth of the Tertiary west Road River and the CottonwoodCanyon, of which the Tertiary Mine channel is

- 71 - probably the doi~r~-strean end. Drainagein the Tertiary :;estRoad River was reversed between the former mouth of this river and I..%itesSanding. There was thus formed a detouraround the old valley, v;hich theriver again entered near the mouth of the Cotton- wood River.

The pre-volcanicsoutherly-flowing Fraser River probably followed the present Fraser 2iver Valley as far as the south end of Noodpscker Island,although there are no exposures of its sediments in this part of theriver. Its occupancyof the now largely-filled andabandoned valley between Woodpecker Island and the mouth of the Cottonwood River is provedby an exposure of its sediments on Can- yonCreek and also by thepresence of Australian members (a) of the FraserRiver formation on Canyon Creek, as the latter were the result o.? the damming of this river by the eruption of the Lower Lavas .

The position of this ancient valley is desoribedunder "Topographjr" 2nd "Bed-rockGeology." From Woodpecker Island to a point a short distance below the mouth of Canyon Creek, t'ne Fraser River r"lo:vs just outside the west rim of this ancient valley and occupiesthe western side of this valley for the remaining short distance to IVhitesLanding. At this point the river makes a wide detourto the west flowing westerly, south-westerly andsouth- easterly to cut through the west rock-rim of the ancient valley and re-enter it just above the mouth ofthe Cottonwood River. This ancient valley was occupied apparently not only by the northerly- flowing Fraser River but also by the southerly-flowingpre-volcanic 2nd subsequentTertiary Fraser Rivers up to andincluding the inter- volcanicFraser River. The latter appearsto have occupied a position within it somewhat to the west of thepre-volcanic Fraser Riverdoubtless owin& to accumulation of sedimentsin the eastern part. At this timethe %est Road Riverjoined the inter-volcanic FraserRiver at KhitesLanding. That part of theFraser River Valleybetween the mouth of theTer-tiary !4est iload River (half a mile above the present mouth of this river) and the mouth of the Cottonwood River was non-axistent.

The severalexposures of Tertiarygravels of the \Jest Road Riverbetween its mouth 2nd WhitesLanding clearly prove that this part of the bend is the down-stream part of the Tertiary !,!est Road River,which formerly joined the Fraser River at Xhites Landing,and that drainage in this part of the river has been reversed. An exposureof the Tertiary West Road Rivergravels is overlain at \

Continued uplift in late Tertiary time enabled tho powerful Fraser Riverto again re3uvenate rapidly anderode the dams caused by t'ne eruption of the Miosene (?) Upper Volcani.cs. It is possiblethat sediments on the east bank of theFraser River op- positesouth Fort George, also the buried channels 1yin.g respectively (1) immediatelyeast of the Fort GeorgeCanyon, (2) east of theriver at Alexandria Ferry, and (3) westof the river a shortdistance up-strea? from the last-mentioned point, are all of Plioceneage, although owing to lack of criteria, it is not possiblo to make a definite assertion on thepoint, because all these may be of interglacialage. In anyevent they prove that deep incision hadagain been accomplished at any rate prior to , the endof the Pleistocene epoch.

- 73 - Irrespective of the question of origin at different paints, the formof the.Rocky Mountain Trench, save in the region of the breaknoted in this report, is comparativelysimple. The south- westernwall of the trench is formed by the eastern slopes of the SelkirkMountains, and northerlymountain groups, while tie westernslopes of the Rocky Mountainsform the north-easterly' wall of thetrench. The topographyin the region of the break, thelength of which is about 100 miles, is described in detail under"Topography," and is radically different.

- 74 - Inthe following table, age is based upon palaeon.tologica1 evidence when such is available. All determinations Of fossils were made by thePalaeontological Section, Department of Mines and Resources,Ottaria.

TABLE OF FOWUTIOiiS

(Tentative )

Tertiary Mine - Canyon Ninechannel Lacustrins deposits in Fraser giver Valley and tributary valleys. Miocene Intra-'UpperVolcanics Fraser River sediments. Upper Volcanics,chiefly basalt flows.

Diatomitsdeposits (Members (c) of FraserRiver formation). Flat-lying tuff'beds of Borseflyarea (HnnualXeport, Olipcen Ministerof Mines, British Columbia,1439, Page C 29). Inter-volcanicFraser River sodimsnts (Membe.rs (b) of FraserRiver formation).

Unconformity

Australian members (a) of FraserRiver formation (oon- taia pebbles of Lower Lavas,but no intrusive igneous bodies). Inclined tuff beds of EIorsefly area with intercalated basaltflows of Lower Lavas(Annual Report, Rinister of Nines,British Columbia, 1938, pp. C 1s to C 21).

I Unoonformity Zocene Lower Lavas--dykesand sills. Intra-LowerLavas Fraser River sediments Lower Lavas--andesiteand basalt flow.

Unconformity I Pre-volcanicsoutherly-flowing Fraser River Sediments.

- 75 -