THE ASSINIBOINE DELTA. 381 



Five to 10 miles west of Portage la Prairie till with frequent bowlders 

 forms the surface, or is underlain only to the depth of a few feet by tlie 

 sediments associated with this delta. Again, 10 miles farther west, the sandy 

 eastern slope of the delta in the vicinity of McGregor shows very rarely 

 projecting bowlders, the size of the few noticed being from 2 to 6 feet in 

 diameter. They probably lie on till that has been somewhat eroded by the 

 lake waves, so that these bowlders are not embedded in it as usual, while 

 the sand and silt afterward spread there on the surface are not sufficiently 

 thick to conceal them. No bowlders were elsewhere seen on the general 

 surface of the delta and of the great area of associated lacustrine silt, nor in 

 any observed sections of these deposits. 



