BIG OR MAUVAIS BUTTE. 171 



lobate outline of the ice-sheet in its retreat, with its morainic accumulations, 

 have given to the postg'lacial Sheyenne River its circuitous coui-se far to 

 the south, o^"er the Cretaceous plain, thinly covered by drift. The country 

 adjoining- these lakes generally consists of the Fort Pierre shale to a height 

 10 to "25 feet above their levels, as is ascertained by Avells, while in the 

 Big Butte, and probably also in the most massive of the hills on their 

 southern shores, the shale rises much higher. Both lakes are now without 

 outlets, but distinct beach lines, which are described in Chapter XI, in the 

 discussion of past climatic changes in this district, show that during the 

 recession of the ice they were raised nearly 25 feet above the present level 

 of De%als Lake, being then confluent, with an outlet from the southwestern 

 arm of Stump Lake southward to the Sheyenne. 



West of Minnewaukan the compound Fergus Falls and Leaf Hills 

 moraine forms a belt, 2 or 3 miles wide, of low hills, ridges, and swells of 

 till, with plentiful bowlders, rising 25 to 50 or 75 feet, but inconspicuous 

 in any distant view, through the central and northwest part of township 

 153, range 68 ; and thence curving northward it passes through to\\n- 

 ship 154, range 69, to the west and highest portion of the Big Butte, or 

 Mauvais Butte, as it is called by the French and Indians of Turtle Moun- 

 tain. This prominent massive ridge of high land extends 10 miles from 

 east to west and west-northwest, through the north edge of township 154, 

 range 68, the northeast corner of the next township west, and the southern 

 third of township 155, range 69. Its eastern 6 miles, to the west side of 

 section 1, township 154, range 69, has a very smooth contour, and con- 

 sists supei-ficially of till, with the scanty proportion of bowlders generally 

 observable on its lower areas. No morainic accumulations were seen on 

 this part of the Big Butte, and the drift-sheet here is doubtless of similar 

 depth (25 to 50 or 75 feet) as on the surrounding smoothly undulating 

 country, above which this ridge rises 150 to 200 feet, to a height 1,650 to 

 1,700 feet above the sea. Its top along this distance is nearly level or only 

 slightly undulating and rounded upon a width of 1 to IJ miles. 



But the western 4 miles of the ridge is covered with irregular morainic 

 deposits and a wonderful profusion of bowlders, giving to it a very rough 

 contour, strongly in contrast with that on the east. A slight depression, 

 sinking to about 1,600 feet al)(>ve tlie sea, intervenes between the smooth 



