BOTANICAL INFORMATION. 655 
Prevailing colours, white and yellow. "The foliage passing 
through every shade, from deep dull green to silvery white. 
Ist Sub-region.—Extensive depressed tracts of the great 
plains, on the sources of Platte River and the Colorado on 
the West, being subterraneous continuations of the southerly 
spurs of the Black Hills. — They consist of great ranges and 
detached piles of horizontal new red sandstone based on 
deeply inclined masses of the coarsest conglomerate, rarely 
directly on bituminous shale, under the great detached piles, 
or near river-defiles. The depression is about 200 feet 
below the general level of the plains above. 
In traversing the great sandy deserts, the traveller's atten- 
tion is excited by numbers of obtuse conical piles, towering 
above the level of the plains, and forming a sort of belt 
north and south in the south-pass along the horizon.— 
Northward, leaning on the pine- and snow-clad central chain 
of the R. Mountains; southward, losing themselves in the 
endless plains of Upper California. Suddenly the traveller 
finds his course arrested by a precipice, he surveys it with 
wonder, and imagines the exhumed ruins of Herculaneum or 
Pompeii are before him. Spacious streets and avenues of level 
rock, formed by regular ranges of new red sandstones haped 
into grotesque ruins, or high massive piles of conglomerate, 
containing globular, oblong, or columnar boulders imbedded in 
a grayish soft claystone cement. These boulders are of great 
size, smoothed by trituration, sometimes partially freed from 
cement, fronting the main pile and resembling columns, 
Statues or monuments of every shape. On the top rests the 
obtuse, conical cupola remnant of sandstone, surrounded by a 
variety of small turrets, bearing likewise on their summits 
curiously shaped cupolas of greenish or brownish sandstone. 
In another direction is a series of low, oblong, angular 
platforms of sandstone, resembling tombs, or extensive ter- 
races of astonishing regularity, with basins full of brackish 
water; piles of globular boulders, or obelisks, balancing a 
curious block of sandstone, may be met with here and there in 
the spacious plains. The outlets are mostly narrow, dark 
