But these east-and-west cliffs and the plateaus which they form are
divided by north-and-south lines in another manner. The country has been
faulted along north-and-south lines or planes. These faults are breaks
in the strata varying from 1,000 or 2,000 to 4,000 or 5,000 feet in
verticality. On the very eastern margin the rocks are dropped down
several thousand feet, or, which means the same thing, the rocks are
upheaved on the west side; that is, the beds that were originally
horizontal have been differentially displaced, so that on the west side
of the fracture the strata are several thousand feet higher than they
are on the east side of the fracture. The line of displacement is known
as the Echo Cliff Fault. West of this about twenty-five miles, there is
another fault with its throw to the east, the upheaved rocks being on
the west. This fault varies from 1,500 to 2,500 feet in throw, and
extends far to the northward. It is known as the East Kaibab Fault.
Still going westward, another fault is found, known as the West Kaibab
Fault. Here the throw is on the west side,--that is, the rocks are
dropped down to the westward from 1,000 to 2,000 feet. This fault
gradually becomes less to the northward and is flexed toward the east
until it joins with the East Kaibab Fault. The block between the two
faults is the Kaibab Plateau. Going westward from 60 to 70 miles, still
another fault is found, known as the Hurricane Ledge Fault. The throw is
again on the west side of the fracture and the rocks fall down some
thousands of feet. This fault extends far northward into central Utah.
To the west 25 or 30 miles is found a fault with the throw still on the
west. It has a drop of several thousand feet and extends across the Rio
Colorado far to the southwest, probably beyond the Arizona-New Mexico
line. It also extends far to the north, until it is buried and lost
under the Pine Valley Mountains, which are of volcanic origin.