444 THE GLACIAL LAKE AGASSIZ. 



The remaining six, enumerated in the same order, are designated, from 

 places of their typical dev^elopment in Manitoba, as the Gladstone, Burnside, 

 Ossowa, Stonewall, and two Niverville beaches. Like the shores marking 

 the higher stages of the lake while flowing southward, these beaches are 

 found to have a northward ascent, due to the diff"erential uplifting of the 

 eai-th's crust. The gradual decrease of their ascent from a considerable 

 amount along the earlier and higher shore-lines to very little along the 

 latest and lowest shows that the northward uplifting was in pi-ogress while 

 the ice barrier was receding. It had been nearly completed before the 

 glacial recession uncovered the area traversed by the Nelson, changing 

 Lake Agassiz to Lake Winnipeg. 



Beyond the limit of my survey, which was extended into Manitoba to 

 Gladstone and Orange Ridge and to the south ends of Lakes IVLanitoba and 

 Winnipeg, very interesting observations of the l)eaches east and northeast 

 of Riding and Duck mountains are supplied by Mr. J. B. Tyrrell in his 

 exploration of that district for the Canadian Geological Survey.^ It is there 

 found that the earlier shore-lines of the series formed during the northeast- 

 em outflow were uplifted about a foot per mile from south to north for 150 

 miles northward from the latitude of Gladstone, and that this rate dimin- 

 ishes in the successively lower beaches. According to my correlation of 

 Mr. Tyrrell's observations with my own in southern Manitoba and south- 

 ward, the last shore-line known to have been formed by Lake Agassiz is 

 about 60 feet above the south end of Lake Wimiipeg and 80 feet above its 

 north end, ha\nng thus a northward ascent of only 20 feet in a distance of 

 about 275 miles from south-southeast to north-northwest. Here, too, as in 

 the earlier uplifting of the large region on the south, the upward movement 

 of the earth's crust was interrupted by stages of repose or of only very 

 slow progress, affording time for the accum^^lation of beach gravel and 

 sand; and these recognized shoi-e marks are most numerous northward, 

 where the extent of the uplift was greatest. The Emerado beach thus 

 seems to be represented in Mr. Tyrrell's observations by two beaches on 



'Geol. and Nat. Hist. Survey of C.auacla, Annual Report, new series, Vol. Ill, for 1887-88, Part E, 

 16 pages, with map. Hulletin, G. S. A., Vol. I, 1890, pp. 395-110. Am. Geologist, Vol. VIII, pp. 19-28, 

 July, 1891. 



