8 XoRMAN A. Wood 



and vSteele. The plain varies in width from about 200 miles at the north to 

 100 miles at the south and has a general elevation of from 1,500 to 1,800 

 feet above sea level. It lias a gradual, gentle slope eastward from the 

 Coteau du Missouri and southward from the international boundary to the 

 South Dakota line. This double slope determines the direction of the drain- 

 age and causes the main streams to take a general southeasterly course. 



The topography of the plain varies from gently undulating to hilly, the 

 differences being due almost entirely to the original disposition of unmodified 

 glacial drift upon a nearly level plain. A few 'low, well-rounded hills, Sully's 

 Hill, Devil's Heart and Blue Hills, partially concealed by drift, are rem- 

 nants of older continuous formations now all but eroded away. Other 'less 

 conspicuous hills are to be found stretching across the prairie in a north- 

 west to southeast direction. The plain is cut by a few abnormally deep and 

 well-defined valleys, such as those of the "James and Sheyenne rivers. Hun- 

 dreds of small lakes, marshy areas, coulees and swales dot its surface. 



In marked contrast to the general topography of the plain are the Turtle 

 Mountains and the Mouse River Valley. Each of these resembles one of 

 the other physiographic regions of the state, and their location within the 

 border of the Drift-Prairie Plain and their peculiar relation to one another 

 still further emphasize the transitional character of this middle plain. 



The Turtle Mountains are a rough, moraine-covered tableland lying mid- 

 way on the Canadian boundary line. They have an area of 600 to 800 square 

 miles and rise, mesa-like, 400 to 800 feet above the surrounding plain, their 

 margin forming a gentle but conspicuous escarpment on all sides. Lakes 

 abound, and this upland is on the whole well timbered and well watered, but 

 poorly drained. The Turtle Mountains seem to be an isolated residuum of 

 strata elsewhere eroded back to the Coteau du Missouri. 



This comparatively small but distinct habitat, well wooded and watered, 

 furnishes a suitable breeding habitat for several species rarely found else- 

 where in the state. These are Grinnell's water thrush, Philadelphia vireo, 

 yellow-bellied sapsucker, mourning warbler, black and white warbler, and 

 hairy woodpecker. The sandhill crane and great blue heron, ruddy and 

 canvas-back ducks, and the western great horned owl also breed here. 



The Mouse River Valley is a glacial lake plain, similar to that of the 

 Red River Valley, the floor of which was formerly covered by the waters 

 of Lake ,'Souris. This plain lies between 1,100 and 1,600 feet above sea 

 level and drains northward through the Mouse River. 



One of the most striking features of the Drift-Prairie Plain is the 

 Devils-Stump Lake basin. The basin extends from the southern 'slopes of 

 the Turtle Mountains and the Canadian boundary southward to a series of 

 prominent hills lying between Devils and Stump lakes and the Sheyenne 

 River. The eastern and western boundary lines are indistinct, but the area 

 of the entire drainage basin is about 3,500 square miles. There is a gradual 

 slope throughout the basin southward to Devils and Stump lakes. The fall 

 is so slight that drainage is poor and small lakes and ponds abound. The 

 coulees are few and shallow and rarely contain running water except in 



