428 W. UPHAM ESKER NEAR WINNIPEG, MANITOBA 



surface, on an extensive area stretching from the vicinity of Birds Hill 

 southeasterly to the southwest part of the Lake of the Woods and to the 

 Eainy Eiver, and continues on large tracts in Minnesota, to the lakes at 

 the sources of the Mississippi and to the Leaf Hills, and thence south- 

 eastward to Minneapolis and Saint Paul. The contour of the greater 

 part of these deposits, through their extent of 400 miles, is flat or moder- 

 ately undulating, and their surface varies in height from a few feet to 50 

 feet or rarely more above the adjoining lakes and streams. In central 

 Minnesota these tracts of. gravel and sand have an elevation that increases 

 from south to north, being 825 to 950 feet above sealevel in the vicinity 

 of Minneapolis and Saint Paul, rising gradually to 1,200 feet in the dis- 

 tance of about 100 miles northwest to Brainerd, and ranging from 1,350 

 to 1,500 feet between the Leaf Hills and Itasca Lake. Thence their sur- 

 face sinks to 1,150 and 1,075 feet in the vicinity of Eainy Eiver and the 

 Lake of the Woods, and is between 750 and 875 feet in the district here 

 especially described, northeast of Winnipeg. 



On each side this broad belt is bordered by areas of nearly the same 

 general elevation, which have mostly a surface of till; and it is to be 

 remarked that the heights of the tracts of modified drift and till are 

 alike determined by that of the underlying rocks on which these super- 

 ficial deposits are spread as a sheet of slight depth in comparison with 

 the gradual change in their elevation. The drift-sheet on this belt, in- 

 cluding both the sand and gravel and the underlying deposits of till, 

 probably varies in its average thickness from 50 to 150 feet, while its 

 central portion rises 400 to 600 feet above ij;s south and north ends. 



The distribution of the modified drift thus foimd on large tracts along 

 a wide belt from Saint Paul to Winnipeg, while it is very scantily devel- 

 oped on a still wider region of Minnesota, North Dakota, and Manitoba 

 southwest of this belt, and likewise is scanty or wanting on its northeast 

 side in northern Minnesota and about Eainy Lake and the northeast and 

 north portions of the Lake of the Woods, seems to be attributable to 

 converging slopes of the surface of the ice-sheet and the consequent con- 

 vergence of its currents, which brought an unusual amount of englacial 

 drift into the ice along this belt, and by which also the streams produced 

 in its melting were caused to flow thither from extensive tracts of the ice 

 on the east and west. The glacial strise of these adjoining areas show 

 that on the east the course of the motion and the descent of the surface 

 of the ice-sheet were from northeast to southwest, but that on the west 

 the glacial currents moved and the ice surface sloped toward the south- 

 east. 



