WA VE-LIKE PROGRESS OF AN EPEIROGENIC UPLIFT. 39 1 



third distance of 74 miles to the international boundary. Its 

 whole ascent thus in 224 miles is 175 feet, by a slope which 

 increases from slightly less than a half of a foot per mile in its 

 southern third to slightly more than one foot per mile in its 

 northern third. This beach extends only a short distance far- 

 ther north, having been formed when the ice-sheet lay there as 

 the northern boundary of the lake ; but the second of the Her- 

 man beaches, slightly lower and later, reaches as far northward 

 as to the limit of my exploration, in the vicinity of Gladstone, 

 Manitoba, and Riding Mountain, and in this distance of 308 miles, 

 from Lake Traverse to the latitude of Gladstone, it has an ascent 

 of 265 feet. In the four successive nearly equal parts of its 

 extent from south to north, namely, 75 miles, again 75 miles, 

 then 74 miles, and lastly 84 miles, it rises respectively about 35, 

 50, 80, and 100 feet ; and almost the whole of this change of the 

 old beach, from its horizontality at the time of formation, has 

 been produced by the gradual uplifting of the lake basin while 

 the ice-sheet was retreating from it. 



The considerably later upper Norcross beach rises in these 

 distances about 25, 35, 55, and 70 feet, amounting to 185 feet in 

 the entire 308 miles. The upper Campbell beach has ascents of 

 about 10, 15, 30, and 35 feet, or 90 feet in all ; and the lowest 

 of the three McCauleyville beaches, marking the latest stage of 

 southward outflow of Lake Agassiz, ascends about 5, 10, 15, and 

 20 feet or a total of 50 feet. It is thus seen that far the greater 

 part of the uplift of this area had been accomplished before the 

 formation of the Campbell and McCauleyville beaches. 



Beyond the limits of my leveling, portions of nearly all the 

 shore lines of Lake Agassiz below those of the Herman series 

 have been observed and mapped by Mr. J. B. Tyrrell, of the 

 Canadian Geological Survey, at localities in northwestern Mani- 

 toba and eastern Saskatchewan, bordering the northern half of 

 this lacustrine area. ' From a careful comparison of the eleva- 



» Geol. and Nat. Hist. Survey of Canada, An. Rep., new series, Vol. 3, for 1887- 

 88, Part E, pp. 16, with map ; Vol. 5, for 1889-90, Part E, pp. 240, with map, sec- 

 tions, and illustrations from photographs. 



