392 THE JOURNAL OF GEOLOGY. 



tions of the beaches noted by Mr. Tyrrell with those determined 

 by my surveys at the south, I am enabled to correlate very sat- 

 isfactorily the two sets of shore lines. The northern continua- 

 tions of the successive lake levels from the upper Norcross beach 

 to the Niverville beaches, which mark the latest stages of the 

 glacial lake, just before the recession of the ice-sheet from the 

 district crossed by the Nelson river permitted it to be reduced 

 to the Lake Winnipeg, are thus identified upon a region lying 

 50 to 200 miles beyond the area examined by me. 



Along the base of the escarpments of Riding and Duck 

 mountains, where Mr. Tyrrell has traced the beaches and deter- 

 mined their heights for a distance of fifty miles between Valley 

 and Duck rivers, that is, between latitudes 51° 15' and 52° N., 

 it is found that a very important differential elevation, increasing 

 from south to north about three feet per mile, took place after 

 the Campbell and McCauleyville beaches were formed, since 

 they are thus remarkably changed from their original horizontal- 

 ity. It is clearly shown here that the uplifting was not uniformly 

 proportionate and regular for the whole area of Lake Agassiz. 

 The chief movements of elevation of its southern and central 

 part, as far to the north as Gladstone, seem not to have extended 

 farther, at least in their full proportion. The district next to the 

 north along an extent of 120 miles, to the north end of Duck 

 mountain, was perhaps only so far disturbed by these movements 

 as was necessitated to connect the rise of the country on the 

 latitude of Gladstone with the continuing condition of maximum 

 subsidence on the latitude of the lower part of the Saskatchewan 

 and the north end of Lake Winnipeg. But there ensued in this 

 district, after the date of the Campbell beach, a great differen- 

 tial elevation, giving to these late shore lines two or three times 

 more northward ascent than that of the Herman beach from 

 Lake Traverse to Gladstone ; and the total change in level of 

 the highest observed beach, probably representing the upper 

 Norcross stage, situated at Pine river, on latitude 51° 50' to 52° 

 N., is approximately 400 feet, as compared with this shore line 

 at Lake Traverse, about 420 miles distant to the south. Nearly 



