194 W. UPHAM — MODIFIED DRIFT IN SAINT PAUL. 



in the high moraine belt of West Saint Paul and Inver Grove, where in 

 its course from north to south that great moraine sinks sufficiently low. 

 This was in or near the northwest quarter of section 7, in the northwest 

 part of Inver Grove township, with discharge thence south through Rich 

 Valley to the Mississippi.* When a slight recession of the ice on the 

 west uncovered two lower passes to Rich Valley, of closely similar height 

 and each on porous gravel and sand, one near Westcott station and the 

 second (necessary to be crossed by the outlet after flowing over the former) 

 two miles farther southeast, on the small plain in the northeast quarter 

 of section 29, Inver Grove, just east of a church and cemeter}^ having 

 in each case an approximate height of 880 feet above the sea, the last 

 small eastern plateaus in Saint Paul, at about 880 and 875 feet, were 

 amassed. 



Englacial Transportation of the Drift. 



The deposits of lake Hamline supply important evidence, as I think, 

 of the englacial transportation and finally superglacial position of a large 

 part of the drift. at the melting away of the ice-sheet. The areas of the 

 several tracts of modified drift described in this paper are approximately 

 as follows : 



Square 

 mile?. 



Summit Avenue plateau 2.0 



Hamline plateau . ] . 8 



Esker ridge extending northeast from the last, with modified drift in Calvary 



cemetery and westward . . 0.3 



Rolling tract connecting the Hamline and Como plateaus . . 0.7 



Como plateau 2.0 



Esker extending northeast to the reservoir 0.4 



Plain southeast of the Reservoir hill 0.2 



Plateau of Western and Phalen avenues 0.3 



Plateau of Western avenue and Lawson street . 0.2 



Plateau north of East University avenue .* 0.25 



Three small plateaus northeast of the last 0.15 



Total. 



» 



Upon these combined areas, somewhat exceeding eight square miles, 

 the average depth of the water-deposited gravel and sand doubtless ex- 

 ceeds 50 feet, and may be fully 75 feet. All this modified drift I think 

 to have been brought by streams which had gathered it from the melt- 

 ing ice surface, where it had become exposed by ablation of the upper 

 part of the ice-sheet, as the Malaspina glacier or ice-sheet in Alaska is 



* N. H. Winchell : Geology of Minnesota, vol. ii, 1888, p. 90. Warren Upham : Bulletin of the 

 Minnesota Academy of Natural Sciences, vol. iii, 1889, p. 56 (read May 8, 1883). 



