TERMINAL MORAINES. 215 



Huron, about sixty miles north of Mitchell, and continues 

 visible upon either side of the river about twenty miles dis- 

 tant, as far up as Aberdeen. 



The western side of this lobe is characterized by corre- 

 sponding lines of receding moraines, the outer of which is in 

 the vicinity of the Missouri River and on its eastern side. 

 Together, these form the Missouri coteau. Everywhere, in 

 coming up from the river on the west to the plateau, which 

 is in most places from four hundred to five hundred feet 

 above the river, one encounters two or three bowlder-cov- 

 ered terraces, the highest of which are at an elevation of 

 from three hundred to four hundred feet. The moraines 

 rise to a considerable height above the general level, and, as 

 upon the eastern side, are everywhere marked features of the 

 landscape. The streams entering the Missouri from the east 

 are all of them short, none being more than forty miles in 

 length. These streams are in all cases bordered by broad 

 and elevated local terraces, the edges of which, where they 

 overlook the immediate trough of the stream, are crowded 

 with granitic bowlders. In some cases, as Professor Todd 

 has shown, these valleys terminate abruptly in the water- 

 parting, as if being the continuation of glacial streams from 

 the east, which had originated upon the ice-lobe while it 

 filled the James Y alley. 



Professor Todd, to whom the exploration of this region 

 was assigned, thus describes the Missom-i coteau : 



This moraine consists of loops, convex usually toward the 

 west and south, but in rare cases toward the northwest, as will 

 be seen. These loops connect at re-entrant angles pointing 

 toward the northeast and east, which are usually sharp, and 

 sometimes are extended into elongated ridges. The moraine 

 varies in elevation with the region on which it rests. Its rela- 

 tive height is usually great at the head of the re-entrant 

 angles or interlobular moraines. These frequently stand out 

 like great promontories, rising from one hundred and fifty to 

 four hundred feet above the plain around them. At the bot- 

 tom of a loop the moraine is apt to be slight or wanting, if on 



