NATURAL AREAS AND REGIONS 



545 



of hills, dotted by many lakes, and 

 gashed by a few deep valleys. Yet 

 farther to the westward the land rises 

 abruptly to the Missouri Plateau, 

 crowned near its eastward margin by 

 the Coteaus of the Missouri. On the 

 northern boundary, about midway of 

 the state, is an old "outlier" of the 

 Plateau, separated from it by the Lake 

 Souris plain, known as the Turtle Moun- 

 tains. At the base of the western slope 

 of the Coteaus and following their 

 general course is the broad valley of the 

 Missouri. It is joined from the west 

 by the valleys of the Little Missouri, 

 Knife, Heart and Cannon Ball rivers. 

 The general topography west of the 

 Missouri River is a combination of 

 broad valleys, gentle slopes, and abrupt 

 buttes. Along the Little Missouri 

 River, extending from 10 to 15 mi. on 

 either side is the well known Bad Lands, 

 but these give way again to the more 

 gentle slope and butte topography 

 before the western boundary of the state 

 is reached. 



2. Climate 



Because of its latitude and continental 

 location the temperatures of North 

 Dakota are very extreme. Summer 

 temperatures of 100F. are experienced, 

 and winter temperatures of 40F. 

 may be expected each year. Long 

 periods in which the temperature reaches 

 several degrees below zero each night 

 are common. The summers are char- 

 acterized by warm days and cool nights. 

 Winter passes quickly into summer with 

 little interim of spring. Rainfall varies 

 from about 12 in. for the mean annual 

 in the western part of the state to 

 slightly more than 20 in. in the south- 

 eastern part. The precipitation is dom- 

 inantly of the summer type. During 

 the spring months, the corresponding 

 figures are 6 and 10 in. respectively. 

 The season normally free from frost 

 varies from a little under 110 days to a 

 little more than 120 days. The snowfall 

 reaches about 30 in. and occasionally 

 comes in the form of the disagreeable 

 "Blizzard." 



3. The original biota 



North Dakota lies in the general dry 

 grassland area and has but little diver- 

 sity in vegetation. However, different 

 areas have more or less distinct char- 

 acteristics, due chiefly to the unequal 

 distribution of rainfall and to differ- 

 ences in soil and drainage. Timbered 

 areas were confined to narrow margins 

 along the stream courses and the north 

 facing slopes of their valleys, to the 

 slopes bordering Devil's Lake, and to the 

 Turtle Mountains. West of the Mis- 

 souri River the forests were almost 

 lacking even in the stream valleys. 

 The typical dominants of the wood- 

 lands were the elm, oak, ash, maple, 

 and box-elder. The aspen particularly 

 dominated large areas in the Turtle 

 Mountains, and the birch, hackberry, 

 and ironwood grew along the Sheyenne 

 valley. Various shrubs and plants 

 formed a secondary layer under the 

 trees and many herbaceous plants 

 occurred, but disappeared where the 

 trees were removed. 



In the mixed prairie type of vegeta- 

 tion of the eastern part of the state the 

 Andropogon grasses dominated. To the 

 westward, with the decrease in moisture 

 the Andropogons surrendered the domi- 

 nance to the grama grass of the short 

 grass country. In the closed drainage 

 areas, rather extensive in the northeast 

 third of the state, marsh plants found a 

 favorable habitat. Among others, the 

 manna and meadow grasses seem to 

 have been the most abundant. 



Wild ducks, geese, and other aquatic 

 birds nested in large numbers in the 

 marsh and lake areas. Prairie chicken 

 and grouse vied with the white-tailed 

 jackrabbit (Lepus townsendii campanius) 

 in populating the uplands and the red 

 squirrel (Sciurus hudsonicus] and cot- 

 tontail rabbit (Sylvilagus floridanus 

 similis) thrived in the woodlands along 

 the stream courses. Upon all of these 

 the coyote (Canis latrans and C. nebra- 

 censis) and red fox (Vulpes regalis} 

 preyed, and the bison (Bison bison) 

 and pronghorn antelope (Antilocapra 



