192 W. UPHAM MODIFIED DRIFT IN SAINT PAUL. 



from the northeast, colored by its portions of sand and clay derived from 

 the red sandstone and shales of the lake Superior region, and the blue 

 (or near the surface yellowish gray) till, which is distinguished, among 

 other features, by its boulders, gravel, and fine detritus of magnesian 

 limestone brought from the extensive limestone areas of Manitoba, on 

 and west of the Red river. These two glacial drift deposits meet along 

 a somewhat devious line extending from the mouth of Rain} 7 lake south- 

 ward to Saint Paul. In this city the drift is mainly from the northeast, 

 but this is thinly overlapped in the west part of the city by the north- 

 western drift. Under that yellowish and bluish limestone-bearing drift 

 formation the northeastern drift continues, however, on this latitude, 10 

 to 20 miles farther west. 



In the east part of Saint Paul a moraine belt of characteristically hilly 

 and knobby till stretches from north to south, and on the southwest 

 side of the Mississippi river it continues southward through West Saint 

 Paul and Inver Grove. This moraine consists wholly of northeastern 

 drift. 



Another moraine extends through Saint Anthony Park and onward 

 west of the Como, Hamline, and Summit Avenue plateaus of modified 

 drift. Thence it crosses the Mississippi and continues south-southeast 

 through Mendota, Eagan, and the southwest part of Inver Grove, into 

 Rosemount township. Superficially, this moraine is northwestern till, 

 with some overwash gravel and sand; but in its deeper part it consists, 

 at least north from the Mississippi river, of northeastern till. West of 

 Inver Grove and Rosemount the northwestern drift is amassed in a very 

 extensive belt of morainic hills, which are the united accumulations 

 corresponding to five distinct moraine belts in southwestern Minnesota 

 and northern and central Iowa. The features appear to me to justify the 

 following interpretation. 



Confluent Currents of the Ice-sheet. 



Toward the line of junction of the northeastern and northwestern till 

 the slopes of the surface of the ice-sheet and its drift-transporting cur- 

 rents converged. Where the latter till overlaps the former, as in the west 

 part of Saint Paul, a glacial current which had passed southwestward 

 was pushed back and its place was taken by a stronger invading current 

 from the northwest. The line of confluence of the' slopes of the ice-sheet, 

 under its capricious melting and the attendant precipitation of rain and 

 snow, was shifted here several or many miles from west to east. 



Finally, when the continued melting of this portion of the ice-sheet 

 laid bare the earliest postglacial land of Ramsey county, the ice on the 



