FORMER GLACIATIONT OF BRITISH COLUMBIA. 91 



be apparent from the following quotation from the summary of his remarks 

 on the glacial geology of the region in question* 



" In attempting to cover with any general theory the traces of the last 

 great period of cold, generally known as the glacial period, in a district the 

 physical features of which are so well marked and so varied as those of that 

 under discussion, much difficulty is felt, owing to the great number of pos- 

 sible combinations of circumstance. The earliest recognized traces of the 

 period of cold are doubtless the markings on the surface of the plateau, or 

 high lands, in connection with it, which indicate the southward passage of 

 massive ice. These, by the observations above detailed, have now been found 

 in different parts of the interior jilateau, for a distance of over 300 miles, and 

 traced up, on Iron Mountain, to a height of 5,280 feet. Erratics and drift 

 material, with evidence of water action, occur to a like elevation. Ulieii 

 compared mth the ice-markings found in the lower vallei/s, and io those of the south- 

 eastern extremity of Vancouver Island, known to be due to glaciers, those of the 

 higher j/aiis of the interior plateau are less definite.^ The rocks are frequently 

 ■well polished, with stria3 faintly marked, and varying several degrees in 

 direction. Ileavg grooving or fluting like that frequently observed inhere true glaciers 

 have been at ivork, is seldoni or never seen, the nearest approach to it being on 

 the summit of Tsa-whuz and Iron Mountains." 



Dr. Dawson infers from all the facts observed by himself that it is " not 

 improbable " that a great confluent glacier did, at an early stage of glacial 

 time, cover the interior of the Province of British Columbia. This sheet, he 

 SAys, need not have been much more than 2,000 feet in thickness, and its 

 greatest efflux was doubtless by the valley and comparatively low country of 

 the Okonagan. If, however, this enormous glacier did discharge itself chiefly 

 through the valley of that river, the evidences of such outflow Avould, bej'ond 

 doubt, be of the most striking character. Enormous moraines would be 

 accumulated all through the region, and the surface far and wide would be 

 covered by erratics, and the piles of debris formed by the action of the water 

 resulting from the melting of the ice, on the detrital material previously 

 brouu;ht down from the reo-ion to the north. An examination of all that has 

 been published by trustworthy observers in regard to the surface geology of 

 that region indicates that nothing of this kind is to be found there. As ad- 

 mitted by Mr. Dawson, however, a considerable portion of this great ice sheet 



* Geological Survey of Cauada. Report of Progress for 1S77 - 78, ji. 150. 



t The author has taken tlie liberty of italicizing one or two passages in the qiiotation cited above. 



