210 Dr. N. 0. Hoist— The Glacial Period and 



colour, containing glacially striated stones of many kinds of foreign 

 rocks. This boulder-clay is overlain by sandstone with Gangamopteris, 

 belonging to the Carboniferous or the Permian system. What cast 

 suspicion on the glacial deposits of Australia was the great thickness 

 ascribed to them, namely, as much as 5,000 feet. But this estimate, 

 which sounds so fantastic, is really founded on a mistake that arose 

 in the following way : — In the valley where this thickness was 

 calculated the morainic beds are obliquely inclined one above the 

 other. By measuring each of these beds and adding the apparent 

 thicknesses together a total was obtained which naturally was not 

 the true vertical thickness. That this in reality is not so extra- 

 ordinarily great is clear from the fact that the solid Silurian rock 

 crops out both at the bottom and on the side of the valley in question. 

 For a 5,000 foot thick moraine to find room between these outcrops, 

 it must lie in a very deep hollow of most unusual and inexplicable 

 shape. 



For my part I think Upham must be accounted right in his 

 contention that the glacial phenomena of South Africa, India, and 

 Australia can be explained only on the supposition that these districts 

 formerly lay much higher than now. Especially does this apply 

 to the Indian glacial district, situate only 20° from the equator. 

 There is no place here for the interglacialist hypothesis, and if 

 a former elevation be not admitted for this district we may justly 

 ask what else can have produced glacial phenomena so near the 

 equator. On the other hand, we may adduce the fact that Kilima 

 Ndjaro in East Africa, said to be about 6,000 metres high, exhibits 

 glaciation although only 3° from the equator. 



But if an elevation of the land in equatorial regions can produce 

 glaciers, what glacial results may we not expect from an elevation 

 in the latitude of Scandinavia, Greenland, and North America? 

 The question is reduced to this : Can we show that during Quaternary 

 times such an elevation really did take place in the three great 

 glacial districts ? It is as a rule difficult to prove former elevation 

 of the land if the region once raised now lies sunk below sea-level ; 

 but in proportion as the oceans that bound North America and 

 Scandinavia have been more closely investigated this proof has been 

 forthcoming, and a considerable elevation of Quaternary age is now 

 fully established both for North America and Scandinavia. 



As regards North America, many geologists, of whom I shall 

 cite only J. W. Spencer,^ have demonstrated that the larger rivers 

 on the eastern side of the continent, from the Mississippi up to the 

 St. Lawrence, have channels clearly excavated beyond the coast to 

 a depth below the sea of " 3,000 feet or more " ; and this naturally 

 indicates that formerly the land was elevated to a corresponding 

 height. Similar observations have been made on the Pacific coast 

 of North America. That this elevation took place at a relatively 

 recent period follows from the fact that the submarine channels are 

 not filled up as they would otherwise have been. 



* "The High Continental Elevation preceding the Pleistocene Period": Bull. 

 Geol. Soc. Amer., 1890, i, p. 65. 



