6 
The Colorado Experiment Station 
region will be given more attention than that of the foothills and 
intermountain regions. 
The Colorado plains constitute a part of what is known as 
“The Great Plains Area”. They comprise all of that region lying 
east of the Rocky Mountains from the base of the foothills to the 
State line. These plains are largely smooth to rolling prairies. 
The Platte River has cut its valley northeasterly from the city of 
Denver to the State line. The Arkansas River has made a valley 
almost directly east and west, just about thru the center of the 
south half of the plains section. The valley of each of these 
streams constitutes a depression. Between them lies a more or 
less flattened ridge of land separating the drainage of the two 
rivers, known as the Divide, or sometimes better known as the 
Platte-Arkansas Divide. Many points on the Divide near the 
foothills reach an altitude of 9,000 feet and even above. Towards 
the east, the sharpness of slope of the Divide area, and its altitude, 
decreases until it is relatively flat at the eastern border of the 
State. These streams and their tributaries cause more or less 
breaks and rugged features to appear in the otherwise smooth to 
rolling surface of the plains. These modifications also produce 
marked changes in soils. 
The climate is mild tempered, but subject to very sharp ex¬ 
tremes of heat and cold, moisture and dryness. The normal rain¬ 
fall, according to government and State records, varies from a 
minimum of close to 8 inches to a maximum of above 18. In years 
of drouth, the rainfall is decidedly less than the normal. In so- 
called wet years, rainfall is greatly above. In 1911 the rainfall of 
the growing season thru the central portion of this region was 
7.69 inches. In 1916 it was 7.38 inches. In the years of 1914 and 
1915, however, the rainfall was nearly three times this amount, dur¬ 
ing the growing seasons. These just about mark the extremes of 
rainfall to be expected, as these four seasons exhibit two of the 
driest and two of the wettest years since rainfall has been re¬ 
corded in the State. 
The region is a vast plain, unprotected by timber or hills; 
as a consequence, it is subject, especially during the spring and 
fall months, to violent winds. A knowledge of these climatic fea¬ 
tures is necessary in order to arrange proper methods of cropping 
and soil treatment. The minimum altitude of the section is about 
3,500 feet, and the maximum is a little over 10,000 feet; conse¬ 
quently the seasons are relatively short and the nights cool. 
