08B0R^\ REVIEW OF THE PLEISTOCENE 



25: 



the deposits of this glacial advance are knoMTi as the old "Diluvium" or 

 the "Oldest Drift;" the advance is termed the Scanian by Geikie. In 

 the Alpine Eegion it has been termed the Gilnz by Penck and Briickner, 

 and the drift deposits have a general thickness of 30m. At about the 

 same time a great ice cap was formed in British North America west of 

 Hudson Bay from a centre known as Keewatin which sent its ice sheets 

 into Iowa and Nebraska. The resulting Nebraskan deposits, consisting 

 largely of compact boulder clays, are often thickly set with woody ma- 



West Longitude 80 from Oreenwic^ 



Fig. S. — Chief centers of North American glaciation 

 Keewatin, Labradorean, Cordilleran. After Leverett. 



terial gathered from forests of spruce and other coniferous species that 

 indicate the development of a cool temrperate flora in advance of the 

 glaciation. ^^ 



It does not appear that a glacial cap of any considerable extent was 

 formed in Great Britain ; but Geikie^^ shows that along the British coast 



*The above correlation is presented chiefly on the authority of Penck and Leverett 

 (op. ctt, 1910). 

 38 Geikie^ James : Tbe Great Ice Age. 2nd Ed. London, 1877. 



