530 



PRE-WISCONSIN GLACIAL DRIFT IN MONTANA 



the high flat-topped ridges of Cretaceous rocks east of the Eocky Moun- 

 tain front in the region of Glacier Park, Montana, are capped with 

 deposits of glacial drift which, because of its topographic relations and 

 surficial modification by weathering, was regarded as much older than 

 the drift in the intervening valleys. The valley drift was deposited by 

 the mountain glaciers at the time of their last extension, which is re- 



Scale 



Figure 1. — Map of Portions of southern Alberta and northern Montana 



garded as having been practically coincident with the Wisconsin stage 

 of continental glaciation. At that time, in 1911, the extension of the 

 high-level drift eastward from the mountain front and its relations to 

 the quartzite gravels, described by Calhoun, Dawson, and McConnell, 

 as found to the eastward, had not been fully determined, neither was it 

 known what was the relation of this pre-Wisconsin drift to the "Albertan" 

 drift of Dawson. 



