482 THE GLACIAL LAKE AGASSIZ. 



permanent uplift has advanced from near the southern border of the glaci- 

 ated area to its central portion, where the ice-sheet was thickest and where 

 it ling-ered in remnants probably long after its principal mass was melted.^ 



According to my correlation, the highest Ijeach observed by Mr. Tyr- 

 rell east of Riding and Duck mountains belongs to the upper Norcross 

 stage of Lake Agassiz, which now has an ascent of 410 feet from its mouth, 

 near Lake Traverse, to Pine River, in a distance of about 420 miles. The 

 rate of ascent of this beach from the latitude of Gladstone to Valley River 

 is about 1 foot per mile, but thence for nearly 50 miles northward to Pine 

 River it somewhat exceeds 3 feet. The same rates of ascent continue, with 

 only slight changes in the Tintah and Caiupbell beaches, for the distances 

 from the latitude of Gladstone to the Valley and Pine rivers. This portion 

 of the western shore of Lake Agassiz had risen almost uniforndy through- 

 ovit its extent while these beaches were being formed. It had been lifted 

 as a whole to the same amount as its southern part near Gladstone, but it 

 experienced scarcely any differential elevation or tilting until after the 

 formation of the Campbell beaches. 



The rate of northward ascent of the upper McCauleyville beach is 9 

 inches per mile between Gladstone and the Valley River, and thence 

 northward for 56 luiles to the Duck River it ascends a little more than 

 2 feet per mile. In the case of the upper Blanchard beach, the lowest 

 noted near the Valley River, these rate- of ascent are respectively 8 inches 

 and 2 feet. 



After Lake Agassiz began to outflow northeastward, the differential 

 northward uplifting of this district of the Riding and Duck mountains went 

 on rapidly, .anaounting probably to 70 feet within the distance of 50 miles 

 next northward from the Valley River during the time between the upper 

 Blanchard beach and the lower Emerado beach. The latter has an ascent 

 of only 60 feet in about 110 miles northward from Gladstone to the Pine 

 River, while in the next 40 miles north to Kettle Hill it rises, like the 

 preceding Hillsboro beach, 1 foot per mile. 



Below these shore-lines the later lake levels have been changed com- 

 paratively little from their original hoiizontality. In the distance of 150 



'Jotirual of Geology, Vol. II, iqy. 383-395, May-June, 1894. 



