Mesozoic and Ccanozoic Geology and Paloiontology. 231 



In Nova Scotia and New Brunswick tlie Bowlder clay or unstratified 

 drift varies from a stiff clay to loose sand, and its composition and 

 color generally depend upon those of the underlying and neighboring 

 rocks. Thus over sandstone it is arenaceous; over shales, argillaceous; 

 and over conglomerates and hard slates, pebbly or shingly. The great- 

 er part of the stones contained in the drift are, like the paste containing 

 them, derived from the neighboring formations; though, in some in- 

 stances, the}' have been transported from a distance. The transported 

 bowlders have generally been drifted southward, though some have 

 been carried northward, and others in different directions. They have 

 especially been drifted from the more elevated and rocky districts to 

 the lower grounds in their viciuit}'. The striae upon the rocks vary 

 from north and south to east and west, though there is a general ten- 

 dency' to a southern and southeastern course. 



Alfred R. C. Selwyn* found man}^ fine examples of ice-grooves and 

 scratches on the rocky shores of Vancouver's Island, where they 

 occur in different directions, and sometimes nearly at right angles to 

 each other. He quoted, with approval, the statement of Prof. J. D. 

 Whitney, that northern drift does not occur in California, and that no 

 evidence of its occurrence has yet been detected on the Pacific coast, 

 as far north as British Columbia and Alaska. This conclusion having 

 been arrived at on the authority of Mr. W. D. Dall, naturalist, attached 

 to the Collin's Overland Telegraph Company, and who states that 

 though he had carefully examined the country over which he had 

 passed, in Alaska, for glacial indications, he had not found an}^ effects 

 attributable to such agencies ; and that no bowlders, no scratches, or 

 other marks of ice action had been observed by any of his party, 

 though carefull}' sought for. And that inland, neither Mr. Selwj'n nor 

 his assistant Mr. Richardson observed any. 



That the superficial deposits of British Columbia are chiefly de- 

 veloped in the ancient terraces or benches, which, throughout the coun- 

 tr}', are wonderfully regular and persistent, occuring from the coast up 

 to elevations of nearly 4,000 feet, in the passes of the Rocky mountains. 

 The}' give a marked and peculiar character to the scenery of the river 

 valleys, rising like gigantic stairs, to elevations of sometimes more than 

 four hundred feet above the adjoining river or lake. In some places 

 two, three, four and five distinct steps can be seen ; while often they 

 have either become merged into one by subsequent denuding agencies, 



* Geo. Sur. of Canada. 



