IMAGE EVALUATION TEST TARGET (MT-3) / O ^ ■^j *#A ^ ^ :A 1.0 ^ a, IIIIM I.I 11.25 la m *^ 140 M 1.8 1.4 111III.6 9> y] /: ^^c^: 7 ^"^ .* ^^^^j' ^^*, <*■ R? CIHM/ICMH Microfiche Series. CIHM/ICMH Collection de microfiches. Canadian Institute f Historical Microreproductions institut canadien de microreproductions historiques 1980 Technical Notes / Notes techniques The Institute has attempted to obtain the best original copy available for filming. Physical features of this copy which may alter any of the images in the reproduction are checked below. L'Institut a microfilm^ le meilleur exemplaire qu'il lui a 6t6 possible de se procurer. 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The last recorded frame on each microfiche shall contain the symbol — »► (meening CONTINUED"), or the symbol V (meaning "END"), whichever applies. The original copy was borrowed from, and filmed with, the kind consent of the following institution: National Library of Canada Maps or plates too large to be entirely included in one exposure are filmed beginning in the upper Iflft hand corner, left to right and top to bottom, as many frames as required. The following diagrams illustrate the method: Les images suivantes ont 6x6 reproduites avec le plus grand soin, compte tenu de la condition et de la nettetd de I'exemplaire film6, et en conformity avec les conditions du contrat de filmage. Un des symboles suivants apparaitra sur la der- nidre image de cheque microfiche, selon le cas: le symbole — •► signifie "A SUIVRE", le symbole V signifie "FIN". L'exemplaire film6 fut reproduit grflce d la g6n6rosit6 de I'dtablissement prdteur suivant : Bibliothdque nationale du Canada Les cartes ou les planches trop grandes pour Stre reproduites en un seul clich6 sont filmdes d partir de I'angle sup6rieure gauche, de gauche d droite et de haut en bas, en prenant le nombre d'images ndcessaire. Le cJiagramme suivant illustre la m^thode : 1 2 3 4 5 6 hh /2. (From the Canadum Naturalist, Vol IX. Xo, 1.) " " "^ i iNOTES ON THE GLACIATION OF BRITISH COLUMBIA. By GE.)nr;K M. Dawsox, U.S., A.ss.,, . K.S.M , I'.G.s., (if tin- (i, t)lo-i(a) Siirvty of Caiiiida. While engnoed in ooological work in Briti.li Columbia duriu-. the reasons oflHTo and ISTil many points bearing on the -.laci^d period, or epoch of cxtrome cold and ureat accumulati;ion of the con- tinent. T])C Rocky Mountains, properly so called, form the boundary bf tweeu tlic belt of tlic Cordilleras and the great plains to the east. Tlie south-eastern flank of this system is defined by a remarkably deep and straight valley, in which lie consider- able portions of the courses of the hirgest rivers of the country. Beyond this valley to the south-west, is a second and broader mount.'iiu region, called by various names in different parts of its length., but which may be designated as the Selkirk or Gold Kange. Many of tlie summits of tliese mountains are scarcely less in altitude than these of the llocky Mountains, which fref|uently surpass 90(10 feet. Nearly parallel to these two great ranges is the Coast or Cascade ]{angc, in wliich the average altitude of the higher peaks may be stated as between <>000 and 7' occured during botli the first and second eold periods, or during tlie second only. !>. If the north-tn-south glaciation has been produced by glacier-ice, it must have been either ('/) by the action of a great northern ice ca]) (against whicli grave difficulties appear), or (/>) by the accumulation of ice on the country itself, especially on the mountains to the north. In either case it i^ probable that the glacier filled the central phiteau, and, besides passing south- ward, passed seaward throuuh the gaps and fjords of the C'oast Kange. The boulder-clay must liave been formed -dong the front of the glacier during its withdrawal, in water, either tliat of the sea, ()!• of a great lake produced by the blocking by local glaciers of the whole of tin; valleys leading from the plateau, to a depth nf ovei' :)t»00 feet. 10. If general submergence to over 50(M) fct be admitted, the Japan current would flow strongly through Behring's Strait. and over part of Ala>ka, while arctic ice-laden water, passim; south across the region of the great plains, would also enter the central plateau of British ('olumbia, accounting for the north- to-south glaciation and sin)ultaneous formation of tlie boulder- clay. To these conclusions the facts met with during the continua- tion of the geological work in ls77 and the past summer, enable some very interesting additions to be made, all which tend to show that the opinions previously formed are in the main correct. The region examined in l!-77 embraced the southern portion of the Interior Plateau, with portions of tl\e Coast and Gold Ranges. Evidence of the north to south glaciation above referred to. were found in a number of additional localities, on the higher parts of the sonthern portion of the plateau, and traced to a lieight, on Iron Mountain at the junction of the Rivers Nicola and Coldwater, of 5280 feet. Tliese observations, with those of former years, cover a portion of the Interior Plateau over three hundred miles in length, and sliow that the ice pressed onward over the southern portion of the plateau to, or even beyond the ._ 5 lino of the 4ntli pnriilld, not\vitli.>^tiin(liiiu fhc20iiovally monntt.in- nus character of tliat p.irt of the roojon. Travdled houldors and stones rounded by wiiter action are found at like liri-hts v.Ji tlie striation, occurring even at the suiuiiiir of Trni, Mnnn t'-in ; and over tlic greater portion of the region, from tlie eastern |-lopes uf the elevated land of the coast rangos. is spread a cover- ing of drift material, more or less abundantly char-ed with -rratics, and wliere not modified by water action -ub.LMinent to its deposition, to be referred to tlie boulder elay. Terraces, or "benches," are in many places in this part of the provincn shewn in wonderful perfection, rising tier above ^ier from the bottoms of the valleys, till they are found in a m..re ur l,,ss wasted state encircling tlie higher portions of the plateau remote from the nver-courses. These in several places exceed 35(1.) feet in altitude above the level of the sea, but none so hioh as that previously observa.d on Il-ga-ehuz Mountain, in the nortl.^rn part of the province, were found. In the valleys connected with the Thompson, md specially abcmt Kamloops Lake ana remarkable hori/.ontally-sti;,tifiL'd .h^posit of white .ilt. in the form of terraces. These are evidently remnants of a sliect of similar material, which !ns at one time formed tlie floor of these wide trough-Hke valleys. In composition it resembles the white silts of the Xechacco Basin, but eecurs at a different horizon, reaching :; maximum lieiglit, so far as ascertained, of about ITdO feet abov." the sea. In origin it is probably like tliat of the Nechacco, a deposit from the turbid waters of glaciers at a time when the ice still had a considerable extension iV.un the various mountain ranges, and general depression of the land or the damming up ^of the valleys gave rise to a system of winding water-way.s— lakes oi- fjords—which occupied 'the main depre'T. ■sions of the surface. The heads of these valleys, in the flanks of the Gold Range, still hold long and deep lakes, .m tin- banks of which drift deposits appear to bo scarce and the white silts are not found. I refer in this connection particularly to the system of valleys occupied by thr- Shuswap Lakes. It appears not improbable that at the time the wliite silt- were laid down the portions of the valleys now held by these lakes were filled witli glacin- iee, and that eventually a ratlier rapid dissolution 6 tion occurrinu, tlio beds of the ohieiiTs were left as hollows to become lakes. Whether any of these are true rock-basitis can not be deternilned, as t! e material flooring' the lower portions of the wide valleys is alto-;ether detritul. A moraine appears to lie across the valley at the lower end of Little Shuswap Lake. Explorations along the coast of British Columbia, and more especially in the (^ueeii Charlotte L'ands. durinu; the past sum- mer, have developi'd additional interesting details bearing' (in the glacial period. Tiiese have not yet been worked up, but the main points are as follows. The great glacier which tilled the Strait of Georgia, overriding the soutli-eastern extremity of Vancouver Island, may be attributed with greatest probability tr the earlier and more intense period of glaciation. Its motion was from north to .south, but wliether this indicated a gt-neral glaciation of the coast in that direction, or was due entirely to +he contour of the land, was not known. It was evident that had any polar icecap or southward-moving glaciating ridge of ice been the agent, it must also have followed the wide sound separatitig the north-western end of A'ancouver Island from the mainland, in a south-eastward directiou. This has not occurred, but. on the contrary, a glacier eijually massive with that of the Strait of Geoi-gia has poured out of this sound north-westward, sweepim;- over the nortliern portion of \''ancouver and adjacent islands. From a point nearly opposite thu middle of Vancouver Island, where the channels separating it from the coutinental shore are most contracted, the ice has flowed south-eastward, forming the Strait of Georgia glacer, and north-westward as that of Queen Charlotte Sound. North of \'aucouvcr Island, wherever looked for in the proper situations, marks of heavy glaciation are found in all the channels and fjords, to the southern extremit\ of Alaska where my obser- vations terminated, tliotigh a coast-line similar in its general features, and doubtless characterized by the same signs of a former glaciation. extends far to the north-westward. The glacier ice has not only filled the narrow fjords to a great depth, but passing westward has occupied the wider straits which separate the outer islands of the group whicli fringes the coast. In the Queen Charlotte Islands, parted widely from the mainland, traces of local glaciation only, due to ice accumulating on its own mountain system, are found. The northern shore of these islands is however strewn with erratics which may have ■HiiiiiiHiMBMflliHiiil eonic from the uji'iulancl. AIoiil; the oiisteni shore of (jlrahiim Island, a long line of eliffs displays deposits of clays and sands similar to those previously described asoecurrint;' in the southern part of Vancouver Island. .Many of the beds contain boulders and some hold marine shells of the species i'ound in the deposits just referred to, with occasional fraiinients of wood. Quite recently, a great addition to our knowledge of western geology has been made by the publication by Clarence King of the volume of his series on the fortieth parallel, devoted to sys- tematic geology. In this the (|uaternary period is treated at some length, and in a cnniprelu-nsive manner, enabling comjtari- sons to be drawn between the condition during the glacial period of that part of the Cordillera system included in British Colum- bia, and its southern continuation in the vicinity ol' the fortieth ])arallel. King lias failed to find any evidence of a great soutliward- moving ice-mass, or general glaciating agent, and no sheet of boulder-clay covers the region ; the superlieial deposits being either directly due to the descent of torrents from the mountains and high lands, or to the rearrangement of these by water action in lakes. Two great sheets of water which have been called Lakes Lahontain and Bonneville, si)read widely in the high plateau region between the Sierra Nevada and the Kucky 3Iouutains. Local glaciers were, however, extensively developed, coming down to altitudes uf liOoO to 500(1 feet above the sea in the Sierra Nevada, which was exposed to the moisture-bearing winds of the Pacific, but seldom reaehing below a lieight of TOtIO to SOUd feet in the dryer eastern ranges. These constitute the local expres- sions ol' the general change which I'urther north produced great ice-fields, but at no time was more tlian about one-thirtieth of the area embraced in the fortieth parallel survey covered with ice. The most interesting point established by King, however, is the existence of two }ieriods ol' moisture and fiooding of the lake basins, alternating with two of extreme drought, tlie latter of which still continues. The evidence oi' these is I'ound both in tlie relative arrangement of the stratified and unstratified mate- rials of the old lake bottoms, and in the chemical character of the deposit from their waters. These periods of great precipi- tation arc correlated with great probability with the two epochs of glaciation proved in British Columbia, King, however, adopts extreme views as to the power of glaciers in eroding 8 Viilloy.s, attributing most oC the canous of the region he ha.i ex- auiiuoJ to their action. He draws attention to the V-shaped gortrcs whic'li become U-shaped in theu apper reaches, and sup- poses that the former were cutout by flood waters aeeompanyini; and I'oUowinj; tlie lirst period of ghiciation, while in tlie hitter we have the unaltered work of tho glaeiers of tlie second period, statuig tliat the work of erosion in these valleys has been ab- solutely trivial since the glaciers left them. It is also advanced in support of these views that many if not most of the canons (if which the ago can be determined, have been cut out since Pliocene time.-». and Miut in the surface- of the Archajan nias'^cs which mu't have stood out as islands during long geological periods, nowhere shew the junction of newer formations with them, to follow other than broad rounded curves. To this theory of the origin of canons and mountain-valleys, it may be objected that whatever be the case in the fortieth parallel area, vast post-glacial erosion and the formation of deep valleys and gorges ,-«ince that period have elsewhere been dis- covered ; that glaciers are never now found to exert such active erosive power, and that the idea th;it so sluggish and inert a portion of a glacier as its ,:eve sliould produce the great amphitheatrical valleys or cirque> of the central mountain regions, seems incon- ceivable. Further, the post-pliocene age of the canons, supposing it to be correctly assigned to them in .dl cases, may mean nothing more tlian that the progressive elevation of the plateau area ^y which the cutting down of canons may be explained, was most active about that time. Canons and fjords are in any case rather exceptional phenomena, they occur only, on any hypothe- sis, in regions long raised above the sea level, and the cliauces that such features should be preserved during a depression of the land and afterwards brought to light in the particular por- tions of the lines of contact of newer and older rocks exposed by denudation, are exceedingly small