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.
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