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Parks of Colorado. 357 
occasionally crossed by transverse ridges and the chasms of water- 
courses. ‘The front flank of this bench forms the stupendous 
escarpment of the mountains, everywhere lofty and precipitous. 
It is cut through by innumerable streams, up’ whose gorges ac- 
cess to the upper regions is attained, and the internal contents, 
the evetae, as it were, of the rocks are revealed to sight and 
search, 
Forming the pediment of this stupendous mural escarpment 
is the second brim or bench (being the lowest) in the general 
mountain descent. Here the approaching elevation of the plain, 
the increase in size of the streams, the accumulating debris from 
Zz. above, and the increased atmospheric abrasion, all unite to oblit- 
erate the angularity of the rocks and impair the striking dis- 
tinctness of formation. Forests of pine and deciduous trees 
_ The flora and vegetation is abundant and various. 
atmospheric irrigation becomes uncertain, and the rocks are 
covered with soil or the fragments of their own superficial de- 
Siruction. Immediately following is the broad space occupied 
by the fusion of the mountain base and the plain gently descend- 
ing to meet it. Here isa profile infinitely indented and bro- 
ken ; alternately the sloping ridges protrude their ribs into the 
Plain, and the plain advances its valleys between them to re- 
ceive the streams. This is the region of the placers, where is 
checked in its descent and lodged beneath the alluvian soil 
the free gold washed down by torrents from the overhanging 
sum mits. 
summit asa torn hat. Gypsum, limestones, slates, clays, 
shales, are thus found near the highest summits. decay of 
| the secondary rocks gives extraordinary fertility to the moun- 
1 hand.. 
he primeval Cordillera, constructed 
lly thrown up by stupendous yol- 
m; the secondary rocks 1 
but 
are 
