To shorten our story, let me at once say that
during the periods that the Ordovician, the Silurian and
The Devonian were
forming, the Grand Canyon region was either above water so that it received
none of these sediments, or, if any were deposited, they were almost
entirely removed by the weathering processes before described, ere the
region again sank into the ocean to receive the deposits of the
Carboniferous epoch.
The Carboniferous. During this latter period, more than three thousand feet
of strata were deposited. These are the most striking in appearance of all
the Canyon strata, for they reach from the Tonto shales to the rim, and
consist of three principal strata (with many smaller ones in between). The
largest is the red-wall limestone, which constitutes the base of nearly all
the architectural forms found in the Canyon, and is the thickest of all the
strata. It presents the "tallest" wall of the series. The two separate
walls, one above the other, on the top of the Canyon, as seen in the arms
of the amphitheatre at El Tovar, are the other two wide members of this
Carboniferous period. The lower is the cross-bedded sandstone, and the
upper the cherty limestone. There is a remarkable difference in the
appearance and the material of which these Carboniferous strata are formed,
and those of the East and Europe. We generally think of coal-beds - carbon
when this period is mentioned. Here there are none.
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