8 



UNIVERSITY OF COLORADO STUDIES 



South Park it falls rapidly, descending 4,000 feet in the first hundred 

 miles. The remaining two hundred miles of its course are in the 

 plains, where the fall is more gradual. After leaving the foothills 

 it is joined by Clear Creek, St. Vrain Creek and the Cache la Poudre 

 River. These streams with their tributaries drain the east side of 

 the Front Range and the foothill region north of Denver. Many 

 other streams, which rise in the plains and are dry for a considerable 



Map of Colorado showing principal places from which collections were examined. 



portion of the year, join the South Platte from the north and south, 

 west of 103° 30'. East of this meridian the Platte is without tribu- 

 taries from the south since it flows quite close to the Platte-Republican 

 divide. 



The Republican River is confined to the plains; it rises at an 

 elevation of less than 6,000 feet. Five streams, the tributaries of 

 which are for the most part wet-weather creeks, flow into the Repub- 

 lican River from Colorado. The North Fork of the Republican, 



