170 GUIDEBOOK OF THE WESTERN UNITED STATES, 
As both the character of a country and its scenery depend entirely 
upon the kind of rocks in it and upon their relations to one another 
it is well, perhaps, to outline briefly the essential features of the 
geology of this region before attempting to describe the valley of 
the Gunnison. The most striking element of the scenery along both 
lines of the Denver & Rio Grande Western is the very old granite 
and gneiss that are exposed in the Royal Gorge, the Eagle River 
canyon, and the canyon of Colorado River, on the main line, and 
in the Black Canyon and adjacent parts of the Gunnison Valley. 
These rocks, which are without true bedding, have been crushed 
and folded until their structure is generally very complex. After 
they were crumpled they were planed down by the action of the 
weather and the streams until their upper surface was fairly even 
and probably lay near sea level. The land sank somewhat irregu- 
larly, and on the smooth slopes of the granite were laid down sand 
and gravel, which later 
became sandstone and 
conglomerate. Upon 
shale and limestone, were 
afterward deposited. 
Some of these rocks are 
Figure 45.—Section showing the effect : i and of Cambrian age (see 
soft rocks on the form of a can 
the table, p. m), and 
some are as late as Upper Cretaceous. These rocks then passed 
through many changes caused by uplift and erosion and_prob- 
ably during peveral: epochs were planed down by the streams 
almost to sea level. The latest movement in the earth’s crust has 
been one of elevation, which lifted the region to its present posi- 
tion, many thousands of feet above the sea, where the streams are 
vientoudls attacking the rocks and cutting broad valleys or deep 
canyons, the results of their action depending on the kind of rock 
they encounter. A stream may at first cut down through relatively 
soft limestone and shale and may then encounter the massive granite, 
so that the top of the canyon may be broad and have gentle slopes 
(see fig. 45), whereas the bottom may be no wider than the stream 
that has cut it and may have practically vertical walls. The planing 
this part of the basin has been baked 
ties of the past. Both bituminous coal 
and anthracite are mined in this field 
and find their way to market through 
, Gunnison, The coal output of Gunni- 
son ——— rose per to a maximum 
f 640,984 t n 1910. The output in 
1018 was 582.906 tons, 
