THE UPLIFT GEADUxiL, WITHOUT FAULTING. 483 



miles uortliward from the latitude of Gladstone to Kettle Hill the lower 

 Ojata beach and the Gladstone beach ascend, respectively, 60 and 45 feet; 

 and in 200 miles from Gladstone to the Mossy portage and the mouth 

 of the Saskatchewan the successive ascents of the Burnside, Ossowa, and 

 Stonewall beaches are 55, 40, and 25 feet, or only about 3 inches to 1^ 

 inches per mile. 



The very regular northward rise of the beaches of this lake throughout 

 all their explored extent, nowhere having any abrupt changes of level, 

 indicates clearly tha;t this region has not experienced violent orogeuic dis- 

 turbance nor faulting since the departure of the ice-sheet. Its changes of 

 level, which have been of large amount, as shown by the tilted planes of the 

 former lake surfaces, took place gradually and continued through the entire 

 duration of the lake. They went forward most rapidly vipon the areas 

 which had been latest bared from the retreating ice-sheet, and they were 

 essentially finished, bringing the basin to the same height and attitude 

 as now before the ice barrier was removed from the course of the Nelson 

 River. The continuity of the beaches and the slow and gradual changes 

 in their gradients prove that no faults or dislocations attended the uplifting, 

 tilting, and bending of the subjacent rock formations. 



EASTWARD ASCENT OF THE FORMER LAKE LiEVELS. 



Exploration of the beaches formed on the east side of Lake Agassiz 

 has been mostly limited to Minnesota, because the eastern part of this lake 

 area in Manitoba is covered by forest and is almost wholly without settle- 

 ments or roads, so that for the present a survey of the shore-lines there is 

 impracticable. For the same reasons the upper shores in Minnesota have 

 not been exactly traced east of Maple Lake, which lies 20 miles east- 

 southeast of Crookston. Within the prairie area across which the highest 

 eastern shore has been surveyed and its elevation detei-mined by leveling 

 its northward ascent is about 115 feet in 140 miles, from 1,055 feet above 

 the sea at Lake Traverse to 1,170 feet at the north side of Maple Lake. As 

 on the western shore of Lake Agassiz, the rate of ascent gradually increases 

 from south to north, ranging from 6 inches to 1 foot per mile in its southern 



