Exploration of the Colorado River of the West and its tributaries.: Explored in 1869, 1870, 1871, and 1872, under the direction of the secretary of the Smithsonian institution.

EVENTS IN THE HISTORY OF THE PERIOD OF DIRY LANI). 213
the rains had fallen on the country long enough to carry out ten thousand feet
of rocks, the extension of these beds to the south, which were cut away, and
yet before the overlying Carboniferous rocks were formed as sediments of
sand and triturated coral reefs, and ground shells and pulverized bones,
some interesting events occurred, the records of which are well preserved.
This region of country was fissured, and the rocks displaced so as to form
faults, and through the fissures floods of lava were poured, which, on cooling, formed beds of trap, or greenstone. This greenstone was doubtless
poured out on the dry land, for it bears evidence of being eroded by rains
and streams prior to the deposition of the overlying rocks.
Let us go down again, and examine the junction between these red
rocks, with their intrusive dikes and overlying beds of greenstone, and the
crystalline schists below.
We find these lower rocks to be composed chiefly of metamorphosed
sandstones and shales, which have been folded so many times, squeezed, and
heated, that their original structure, as sandstones and shales, is greatly
obscured, or entirely destroyed, so that they are called metamorphic crystalline schists.
Dame Nature kneaded this batch of dough very thoroughly. After
these beds were deposited, after they were folded, and still after they were
deeply eroded, they were fractured, and through the fissures came floods of
molten granite, which now stands in dikes, or lies in beds, and the metamorphosed sandstones and shales, and the beds of granite, present evidences of
erosion subsequent to the periods just mentioned, yet antecedent to the
deposition of the non-conformable sandstones.
Here, then, we have evidences of another and more ancient period of
erosion, or dry land. Three times has this great region been left high and
dry by the ever shifting sea; three times have the rocks been fractured and
faulted; three times have floods of lava been poured up through the crevices,
and three times have the clouds gathered over the rocks, and carved out
valleys with their storms. The first time was after the deposition of the
schists; the second was after the deposition of the red sandstones; the third
time is the present time. The plateaus and mountains of the first and
second periods have been destroyed or buried; their eventful history is lost;
the rivers that ran into the sea are dead, and their waters are now rolling as
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