DENVER & RIO GRANDE WESTERN ROUTE. 13 



one of the great coal fields of the State, which has only recently been 

 developed. The coal is better than that of the Denver Basin, and 

 much of it finds a ready market in the towns on the plains between 

 Denver and Omaha. 



GEORGETOWN AND MOUNT McCLELLAN. 



The journey to Georgetown is made on a narrow-gage line of 

 the Colorado & Southern Railway and is confined entirely to the 

 valley of Clear Creek, which joins South Platte River about 6 miles 

 north of the Union Station in Denver. From Denver to Golden 

 the general course of the road is up the broad, flat valley, which is 

 irrigated by water taken from the creek higher up. This valley is 

 highly cultivated, and many fields of grain (see PL III, A, p. 7) 

 may be seen from the train. Near the mountains the bottom of the 

 valley is composed largely of gravel and boulders brought down by 

 the creek in times of flood, and crops grown on such soil are scanty 

 even where water for irrigation is abundant. 



Just below Golden (named in honor of Tom Golden, one of the 

 pioneers of this region) the valley narrows and is flanked on either 

 side by flat-topped hills, or mesas,* as they are generally called in the 

 Southwest, about 400 feet high. These mesas are remnants of a once 

 extensive plain formed at this level by streams that planed oif the 

 inequalities of the land. TVliere the beds of rock are horizontal, 

 as they are about Denver, the surface of the plain corresponds to 

 the bedding of the rocks, but where the rocks are upturned on the 

 flank of the mountain, as they are at Golden, they were planed off 

 just the same. • After the streams had reduced the soft rocks to a 

 relatively smooth surface a great flood of lava that was ejected from 

 some vent in the mountains rolled out over the plain and spread for 

 a distance of many miles. When this mass of lava cooled and became 

 consolidated it formed a rock called basalt, which is harder than the 

 soft sandstone and shale upon which it rests, and for that reason it 

 served as a protecting cap when the region was uplifted and streams 

 began to cut the rocks away. Most of the basalt is now gone, and 

 the parts seen from the train are doubtless mere fragments of a once 

 extensive and continuous sheet. The rocks upon which the lava was 

 spread are the Denver and Arapahoe formations, of Tertiary age, 

 and the Laramie formation, of Cretaceous age. 



Behind these mesas, which are outliers or foothills of the moun- 

 tains, is a beautiful valley, which has been eroded in the upturned 

 edges of the softer and lower formations. These rocks can not be 

 seen distinctly from the train, but in near-by localities they are well 

 exposed as they bend upward and rest upon the granite that forms 



* Flat-topped hills are uamed mesas because of their resemblance to a table 

 (Spanish mesa, pronounced maj'sa). 



