178 THE GLACIAL LAKE AGASSIZ. 



moraine, forms a series of six or seven long and narrow lakes, indicating 

 that a larger river flowed here during the recession of the ice-sheet, its 

 deeply eroded channel having since been partially filled by alluvium from 

 tributaries. 



Continuing westward, the Mesabi moraine is apparently represented 

 by liilly drift deposits north of Pokegama Falls of the Mississippi, about 

 Bowstring Lake, the head of the Big Fork of Rainy River, and on the 

 northeast side of Lake Winnebagoshish. Thence it passes west and north- 

 west by the sources of Turtle River to the conspicuous morainic ridge of 

 till with multitudes of bowlders which forms the tongue of land, 9 miles 

 long and about 2 miles wide, between the south and north parts of Red 

 Lake, extending westward to the Narrows, with a height of 100 to 200 

 feet above the lake. At the NaiTOws this moraine sinks beneath the high- 

 est level of the glacial Lake Agassiz, and it forms no noteworthy knolls 

 or hills visible from Red Lake toward the west or northwest. 



The ice barrier of Lake Agassiz at the time of the Mesabi moraine 

 probably extended thence northwest and north across the area of Beltrami 

 Island (described in Chapter VI), and thence farther northward and west- 

 ward to the south ends of Lakes Winnipeg and Manitoba, giving to this 

 glacial lake a length of more than 300 miles. Morainic drift deposits, 

 with plentiful bowlders and typically rough contour, form the eastern 

 end of the Tiger Hills, in township 7, ranges 9 and 10, crossed by the 

 road running south from Trehei'ne ; and this tract, clearly distinct from the 

 Itasca moraine, which forms the western end of this range of hills, appears 

 to mark where the southern extremity of the ice-lobe west of Lake Agassiz 

 still abutted on the north end of the Pembina Mountain escarpment and on 

 the highland south of the Assiniboiue delta during the accunuilation of the 

 eleventh or Mesabi moraine. The highest portion of this delta west of 

 Brandon, the Big Slough, extending thence west from Alexander to Gris- 

 wold, and the gap by which the Souris River flows thi'ough the Itasca 

 moraine, forming the western part of the Tiger Hills, between its elbow 

 and Gregory's mill, all bear testimony, as shown in the description of the 

 Assiniboine Delta in Chapter VI, that for some time the embayed portion 

 of this lake west of Treherne was held by this ice-lobe at a height con- 



