Bird LiFK oi-" North Dakota 7 



Red River Valley with an elevation of from 800-1000 feet. This is bordered on 

 the west by a higher Drift Prairie Plain rising from 1,200 to 1,600 feet 

 above the sea. Still farther west and occupying nearly one-half of 

 the state is the elevated Coteau du Missouri with a surface which rises 

 from 1,800 to 2,700 feet and more above sea level. The state thus repre- 

 sents a considerable range of relief, the lowest point in the northeastern 

 corner being 789 feet above the sea; the highest yet determined, the summit 

 of Sentinel Butte, over 3,100 feet. 



The Red River Valley 



The Red River Valley is not a true valley but an old lake plain, north- 

 ward along the axis of which flows the Red River of the North. The plain 

 is remarkable for its larger level areas and for the fertile soil-lacustrine 

 deposits of silts and clays found on the floor of the ancient glacial-marginal 

 lake. Lake Agassiz. The portion of the plain which lies within North Dakota 

 has a breadth of thirty to forty miles, except at the south, where it narrows 

 to ten miles, and an elevation of from about 800 feet at Pembina to about 

 975 near Wahpeton. 



The boundary between the Red River Valley and the Drift-Prairie Plain 

 is an escarpment so abrupt and rugged in the north as to receive the name 

 of Pembina Mountain. The wooded and dissected character of 'the bluflf 

 accents the contrast with the old lake floor. Near the middle of the state 

 the escarpment fades into a gentle and inconspicuous slope and becomes 

 somewhat more marked again as the south state line is approached. Through- 

 out the entire distance across North Dakota the escarpment bordering the 

 Drift-Prairie I Plain on the east rises 300 to 500 feet above the Red River 

 Valley floor ; in some places the slope is abrupt, in others gentle, but always 

 it is conspicuous in this country of low relief. 



The Red River seems to be the dividing line between several eastern and 

 western species, although Coues (1878, p. 546) says: The bird fauna of 

 this region is decidedly eastern in character, and of the Pembina region, the 

 only western trace 'observed was clay-colored sparrows and Brewer's black- 

 bird. The whip-poor-will, pileated woodpecker, crested flycatcher, phoebe, 

 wood duck, indigo bunting, and screech owl rarely pass westward of the 

 Red River and its valley, while of the western species, the magpie, burrowing 

 owl. Arkansas kingbird (which Dr. Coues did not find in this valley in 1873) 

 now are common as far east as the Red River itself. Several species that 

 Dr. Coues found common in this valley in 1873 have now almost dis- 

 appeared from the region, and one, the passenger pigeon, has become extinct 

 here as elsewhere. 



The Drift-Prairie Plain 



The Drift-Prairie Plain extends from the Red River Valley escarpment 

 on the east to the Coteau du Missouri escarpment on the west. The western 

 escarpment runs from northwest to southeast, passing near Kenmare, Minot 



