Naturally an answer to these questions is mere conjecture, as only from a
study of the facts revealed underneath the present strata, can any
comparative knowledge be gained of the conditions existent at that
prehistoric age.
There may have been one river, or a score, or any number
between, and it is probable one or more rivers carried the Algonkian debris
westward and deposited it, as the Colorado River (not brought into
existence until centuries later) is now doing with the debris of the
existent strata.
Another Subsidence. Now, a new era is about to dawn. Planed and smoothed
off as they are, the Algonkian and Archaean masses are to be submerged once
more in the ever receptive ocean. A period of subsidence occurs, and the
whole area is soon hidden under the face of the sea. But, all around these
are masses, some day to be mountain peaks, that refuse to sink again into
the sea. Then the forces of the air assail them. If they cannot be drowned,
they shall be gnawed at, smitten, cut and worried by the air, the chemicals
of the atmosphere, the storms, the rain, the hail, the frost, the snow, and
thus made to feel their insignificance. Slowly or rapidly, they yielded to
this disintegrating process, and as the rocky masses broke up, they were
washed by the rills and streams into the bed of the sea, where they soon
rested upon the tilted ends of the Algonkian strata and exposed surfaces of
the Archaean masses, waiting for them.
The Deposition of the Tonto Sandstones. The wise men tell us that this
ocean was a salt sea, and that it was quite shallow while these new
sediments were being deposited. Little by little one thousand feet of the
sediments of this epoch were washed down, so that it is very likely that
the tilted strata upon which they rested slowly sank lower and lower to
accommodate them. Then, for some reason or other, there was a rest for a
while - a few hundreds or thousands of years - and the masses of sediments
became cemented into sandstone and shale, which we call the Cambrian
formation, or the Tonto sandstone. This is to be seen resting both upon the
Archaean and Algonkian from the porches of El Tovar. It is composed of
strata of dull buff, very different from the brilliant reds - almost
crimsons - of the Algonkian, and the bright reds of the strata which later
were to rest above them.
Geological Terms. What an audacious science this geology is! How ruthlessly
it wrests aside the curtain from the mystery of the past, and how glibly it
deals with thousands, millions of years, tying them up into packages, as it
were, and handing them out labeled "eras" and "periods." As usual, the
names made by the wise men are hard to pronounce, and seemingly hard to
understand. But a few minutes will take away the difficulty. They divide
the eras into four, viz.: 1, Proterozoic; 2, Paleozoic; 3, Mesozoic; 4,
Cenozoic. All these "zoics" have to do with life. Proterozoic means before
life, and signifies the rocks that contain no fossils indicative of life;
Paleozoic signifies the most ancient forms of life; Mesozoic signifies
"middle life" or those between the most ancient and the Cenozoic, or recent
forms of life. The periods are lesser divisions of the eras. In the
Proterozoic, there are two periods, viz.: the Archaean and the Algonkian.
The Paleozoic has six periods, viz.: the Cambrian, Ordovician, Silurian,
Devonian, Carboniferous and Permian. The Mesozoic era has three periods,
the Triassic, Jurassic and Cretaceous, while the Cenozoic era names five
periods, - the Eocene, Oligocene, Miocene, Pliocene and Pleistocene.
Absence of Certain Strata. 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. In the East, in
England, and in other parts of Europe, vast marshes existed in this period,
and the rank vegetation of these marshy areas formed the coal-beds, with
which the Carboniferous there abounds. It is only by the fossils found that
the periods to which the various strata belong are determined, and the
fossils, millions of which abound in the upper limestone, are clearly of
the Carboniferous epoch.
As these strata and this period bring us to the "rim" of the Canyon, it
might be easy to imagine that the processes of uplift and subsidence, and
deposition of more strata, as far as the Canyon region is concerned, now
cease. Such, however, is not the case.
Later Strata. As we go away from the Canyon, either north or east, we find
thousands of feet more of the later depositions, and the geologists affirm
that many of these at one time may have overlaid the Canyon region.
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