as a a 
Se ee ee ee ee a ee 
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 off the 
inequalities of the land. Where 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 
Neste EE Reh EE EI ig SE EY 
4 
Flat-topped hills are named mesas because of their resemblance to a table 
(Spanish mesa, pronounced may’sa). 
