GLACIATION OF NORTH CENTRAL CANADA I 59 



Two hundred miles still farther north, along the Grass and 

 Burntwood rivers, the striae of the two glaciers cross almost at 

 right angles to each other, the one being clearly later than, and 

 independent of, the other. A little farther east, north of Gull 

 Lake and Nelson River, is a long narrow sandy esker, from 90 to 

 200 feet in height, running east and west, clearly formed by one 

 of the streams draining the Labradorean glacier. This ridge of 

 loose sand would certainly have been swept away, if any glacier 

 had advanced from the north subsequent to its formation. 



Before the fronts of the two great glaciers had separated the 

 eastern one had again begun to retire, and as it retired a thick- 

 ness of from 50 to 100 feet of stratified clays and silts were 

 deposited in the bed of Lake Agassiz, chiefly north of the present 

 basin of Lake Winnipeg, for there some large streams draining 

 the Labradorean glacier discharged into the lake, bringing with 

 them a heavy cargo of glacial mud. The positions of these 

 streams are still marked by long and high eskers, which may be 

 seen near the banks of the Nelson River, crossing the country in 

 a direction parallel to the later striation. 



The Nelson River, in its northern course, from Playgreen 

 Lake to Split Lake, marks the approximate eastern limit of this 

 deposit of stratified clay, and along the eastern shores of Lake 

 Winnipeg the stratified clays were not found at a greater height 

 than 150 feet above that lake, and, except at one place, at no 

 great distance back from its shore. 



The absence of these stratified deposits would tend to show 

 that the eastern glacier had not retired to any considerable dis- 

 tance east of Nelson River and Lake Winnipeg, before Lake 

 Agassiz was drained by the gradual shrinkage of the Keewatin 

 glacier to a small area in the vicinity of Doobaunt and Yath- 

 kyed lakes. 



Subsequently the Keewatin glacier appears to have broken 

 into two or more smaller glaciers, the centers of which lay still 

 nearer the coast of Hudson Bay than the center of the single 

 glacier. One of these centers rested over the hills southeast of 

 Yath-kyed Lake, and from it the ice radiated in all directions, 



