THE GENESIS OF LAKE AGASSIZ 



633 



small thickness of calcareous till is exposed, passing up into lami- 

 nated, stony clay which is overlain unconformably by Lake Agassiz 

 lacustrine clays containing fresh-water shells. The contact is a 

 wave-cut plain. The lacustrine deposits above the wave-cut plain 

 are clayey in character and evenly and thinly bedded, so that it is 

 evident that the water must have risen to a considerable height to 

 permit of such deposition. In places around the southeastern 

 portion of Lake of the Woods these lacustrine deposits are at least 



Fig. i. — Section exposed on south shore of Lake of the Woods, showing at the 

 bottom calcareous till passing upward into laminated, stony clays unconformably 

 overlain by Lake Agassiz lacustrine clays. The contact is a wave-cut plain. 



30 feet thick and rise to an altitude higher than the divide sepa- 

 rating the Lake of the Woods basin from that of the Red River on 

 the west. Furthermore, the first strong raised beach above the level 

 of Lake of the Woods, at the level of which the water must have 

 stood, if not at some higher level, when the lacustrine deposits were 

 laid down, is in the southern portion of the district from 45 to 55 

 feet above the level of Lake of the Woods; and this beach passes 

 over the divide to the southwest of the lake. 1 Hence it follows 

 that these lacustrine deposits were not laid down in a local lake 



1 Minn. Geol. Survey, Bull. No. 12, 1915 (map). 



