Drift in Mitmeapolis, Mitm. — Upham. 291 
changes, but predominantly or wholly eastward. Whatever 
fluctuations of glacial movements may have conspired to pro- 
duce the interstratified condition of the red and gray till, they 
must be ascribed to a time earlier than that of the moraines, 
while yet the ice from the east and west, confluent on this area 
and above the later site of lake Hamline, pushed back and 
forth, interbedding ice and its drift from each side in one con- 
tinuous ice-sheet, to be soon melted and allowed to deposit 
its englacial material. 
Xot far westward, in the region of lake Minnetonka, and 
thence north through the larger parts of Hennepin and Wright 
counties, a great congeries of moraine hills is variously group- 
ed and spread in scarcely distinguishable series. The broad 
confluent belt of the ice-sheet had received much englacial 
drift from each side, far exceeding its average amount, and it 
was heaped during the glacial retreat in these al^undant hills. 
Plains op Modified Drift. 
When the surface melting had reduced the border of the 
waning ice-sheet to the thickness of only two or three hundred 
feet or less, it was covered by the drift which had existed high- 
er in the ice; and at the same time the water of its melting 
and of rains-, washing the drift-laden surface and gathering 
into rills, brooks, and even rivers before coming to the edge 
of the icefields, brought to the land just beyond their boundary 
a vast freight of gravel, sand and clay. This occurred most 
abundantly where the ice held much drift, as upon this belt of 
its former confluence from opposing directions of movement. 
Such plentiful deposition of modified drift, however, was 
not limited to the areas of St. Paul and Minneapolis, but it 
was a very remarkable feature of the time of final melting of 
the ice-sheet upon all the belt of its confluent currents from 
the northeast and northwest across this state. Extensive sand 
and gravel tracts reach from the Twin Cities north-northwest- 
erly through Anoka, Isanti, Sherburne, Benton, Morrison, 
Crow Wing, Cass, Wadena, and Hubbard counties, to Itasca 
lake, and onward in the same course by Red lake and the west 
side of the Lake of the Woods, to the vicinity of Winnipeg.* 
*The Glacial Lake Agassi/., U. S. Geol. Survev, Monograph XX\\ 
1895, PP- 181-188. 
