THE PRE-WISCONSIN DRIFT OF NORTH DAKOTA 523 



of 15 to 20 feet. The bowlder clay appears in a number of the cuts 

 along the Minneapolis, St. Paul & Sault Ste. Marie Railroad north 

 of Bismarck, here generally associated with water-laid drift. It 

 also outcrops at several points on Apple Creek, where it shows a 

 thickness of 10-12 feet. 



DRIFT IN MORTON COUNTY 



West of the Missouri River in Morton County the glacial drift 

 is represented almost wholly by gravel and bowlders, the latter 

 occurring in great numbers. These bowlders, which are mostly 

 granite, thickly cover the surface in many localities, resting 

 directly on the bedrock, and except in rare instances no drift 

 clay is associated with them. In some places they are scattered 

 loosely over the ground, but in many others they form a bed or 

 pavement in which the individual bowlders are in contact with 

 each other. These bowlder deposits or bowlder beds are especially 

 noticeable on the tops of divides and on upland areas. The bowl- 

 ders vary in size from 6 or 8 inches to several feet in diameter, 

 large ones measuring 8 and 10 feet being seen occasionally. 



MORAINES OF LITTLE HEART RIVER BASIN 



The most interesting and notable occurrence of glacial till 

 in Morton County is found in the basin of the Little Heart River 

 where the drift has 

 been heaped up into 

 mor ainic hills . D uring 

 the Glacial Period this 

 basin was probably 

 occupied by an ice 

 lobe of the continental 

 glacier, and this lobe 

 formed the belt of ^ IG " r# — Bowlder-covered moraine hill of the 



. . .... ... pre-Wisconsin drift, Little Heart Basin, northeastern 



moramic hills which Morton County . 



nearly encircles the 



broad valley plain and deposited more or less drift in the pre- 



glacial valleys of the Little Heart and its tributaries. As the ice 



