THE SEVENTH OR DOVRE MORAINE. 149 



enne. Even farther northwest, the glacial Lake Souris outflowed by this 

 stream, as previously at its beginning it ha^ found outlet during the time 

 of the Elysian and Waconia moraines into the upper part of the James 

 Eiver, flowing through Arrow Wood and Jim lakes to Lake Dakota, so 

 long as that lake existed. 



This great affluent, which may be called the glacial Sheyenne River, 

 is marked b»y a flat or in part moderately undulating belt of stratified 

 gravel and sand, extending from the central part of the Fort Ransom 

 militaiy reservation southward by Marshall and Nicholson. It includes a 

 width of li miles to the west and an equal distance to the east of Mar- 

 shall, where it is bounded on each side by higher tracts of smooth till. Its 

 height above the sea at Marshall is 1,343 feet, and at Nicholson, where it 

 widens into the glacial lake of Sargent County, 1,309 feet. Two compar- 

 atively small channels, probably occupied by the stream in winter- when 

 glacial melting was at its minimum, were seen near the west side, on the 

 wide alluvial belt, about 1^ miles and 1 milewest of Marshall, each having 

 a width of an eighth of a mile and a depth of about 15 feet. One of these 

 channels, or the two interlocking and here and there separated by islands, 

 is commonly known as the Big Slough, and has an extent of many miles 

 from north to south. 



During the recession of the ice from the compound moraine on the 

 west line of Sargent and Ransom counties to the Dovre moraine, before 

 described, the glacial lake grew as fast as the land became uncovered, 

 extending gradually east around the northern base of the Coteau des 

 Prairies to Skunk Lake (recently called Lake Tewaukon), northeast over 

 the smoothly undulating surface of till, very abundantly sprinkled with 

 bowlders, about Forman and Lake Kandiota, to the Stormy Lakes and 

 adjacent moraine near Milnor, and northward along the moraine and ice 

 front into Ransom County. Its depth at Forman was 50 feet; at Perry, 

 6 miles east, nearly 100 feet; and farther east and northeast, beside the 

 Dovre moraine, about 150 feet, if it continued tributary to the James 

 River through the whole time of this glacial retreat. 



It is more probable, however, that when the recession of the ice uncov- 

 ered Lake Tewaukon and the country eastward, an outlet was found in 



