8 Life-histories of Northern Animals 



waters of both Saskatchewan rivers, discharging into it, found 

 their overflow near the Elbow and went by way of the 

 present Qu'Appelle Valley into Lake Souris. The sandhills 

 extending west of Griswold are the delta sands of this old 

 Saskatchewan. 



Lake Souris, receiving the waters of the Saskatchewan, 

 Assiniboine, and Souris Rivers, found its overflow in a mighty 

 flood that swept down through Lang's Valley, Rock Lake, 

 Swan Lake, and Pembina Valley to discharge into Lake Agassiz, 

 where it formed an extensive sandy delta, now represented by 

 the sandhills where the Pembina River issues from Pembina 

 Hills, in Dakota. 



But probably the receding of the supposed glacier allowed 

 the overflow of Lake Souris to find a lower channel into Lake 

 Agassiz, by way of the Grand Valley of the Assiniboine, at 

 Brandon. The Carberry and adjoining sandhills are the delta 

 deposits at the new mouth of the great river. The varied 

 forms of these hills are due to the piling and sculpturing power 

 of the wind. 



A further recession of the glacier lowered Lake Saskatche- 

 wan to the level of Lake Agassiz, joining them together at 

 the north of Pasquia Hills, as shown in the map. Thus 

 Manitoba lost the Saskatchewan; for now that famous stream 

 had dropped lower than the slight ridge that cuts it off^ from 

 its ancient channel — the valley of Qu'Appelle — and following 

 the low lands to the north it settled into the bed wherein we see 

 it to-day. 



The average altitude of this Second Prairie Steppe is, 

 according to Dr. George M. Dawson,' i,6oo feet above the sea, 

 or about 800 feet above the first Prairie Steppe. The rise is 

 well shown between Morden and Thornhill where there is a 

 difference of over 300 feet in six miles. 



Dr. George Bryce considers' that the Tiger Hills, Brandon 

 Hills, Arrow Hills, etc., are vast moraines, or dumps of drift 

 material that was side-tracked from the glaciers. 



' Geol. and Resour., 49th Parallel, B. N. A., Bound Comm., 1875, P- 5- 

 * Surface Geol. Red River Trans. Hist, and Sci. Soc. Man., No. 41, 1891, p. 5. 



