THE LITTLE SOURIS. 243 



east end of Sand Hill Lake, 239 miles from the Assin- 

 niboine, and thirty-one miles from the South Branch, 

 the valley is one mile and five chains broad, with 

 a depth of 140 feet below the prairie. Eight miles 

 from the west end of Sand Hill Lake, or fifteen miles 

 from the Saskatchewan, the excavation is one mile 

 and seventy chains broad and 150 feet deep. At the 

 height of land where it has been invaded by sand dunes 

 from the west and south-west, it is still nearly one mile 

 broad and 110 feet deep, estimated from the well defined 

 edge of the valley, where a low escarpment of rock still 

 uncovered by the advancing sand of the dunes, serves to 

 mark its limit and the power of the forces which ex- 

 cavated it. The level of the prairie studded with sand 

 hills and dunes is some 30 feet above the edge of the 

 rock noticed above. 



The Little Souris, or Mouse Eiver, joins the Assinni- 

 boine 140 miles from Fort Garry, by the windings 

 of the river valley, and 116 by the buffalo hunters' 

 trail. At its mouth the Little Souris is 121 feet 

 broad, 3 feet 6 inches deep in the channel, with a 

 mean sectional depth of 2 feet 4 inches, and a current 

 of half a mile an hour. Its valley, at the Back-fat 

 Creek, twenty-five miles from the Assinniboine, is one 

 mile and a half broad (8,016 feet), and 225 feet 

 deep, with a level prairie on either hand. Near Snake 

 Hill, sixty-one miles from the outlet, the valley is only 

 110 yards broad, and 66 feet deep, with open prairie 

 on both sides. The river here is 100 feet broad, and 4 

 feet deep in the channel. In its passages through the Blue 

 Hills of the Souris, the river has excavated a profound 

 valley between 400 and 500 feet deep, making a sudden 

 turn from a clue easterly course to one almost northerly, 

 and avoiding what appears to be an ancient channel but 



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