The human mind cannot realize the
effects of vastness and power this Canyon scenery produces, except when one
stands below the cliffs and looks up.
And where the opportunity is given of
looking both up to towering walls, and down over beetling precipices, the
effect is enhanced.
The Tonto Sandstones. Below the plateau, slight slopes lead the eye to the
last of the stratified rocks, the Tonto sandstones of the Cambrian period.
These are readily distinguished, mainly by their deep buff color and the
fact that generally they are found resting on the archaean or unstratified
rocks, locally though incorrectly termed the granite, which makes the Inner
Gorge through which the river runs. This "granite" is in the main a
blackish gneiss.
The Algonkian Strata. Though the Tonto sandstones usually occupy the
location named, there is a deviation from this in the presence of some
remnants of strata of the Algonkian period, directly opposite El Tovar.
This deviation is discussed in the chapter "How the Canyon was Formed."
These remarkable rocks occur to the left (west) of Bright Angel Creek, and
lie immediately above the gneiss. Their brilliant red reveals them, and
they can be followed up under the base of the Cheops and to a small wash to
the left of Osiris. At the mouth of Bright Angel, they rest upon the
archaean, with the Tonto sandstones above them, but just in front of the
Battleship a break in the gneiss occurs, and on the portion nearest us the
Algonkian strata totally disappear, for the Tonto strata rest directly upon
the gneiss.
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