The low desert, with its desolate mountains, which has thus been
described is plainly separated from the upper region of plateau by the
Mogollon Escarpment, which, beginning in the Sierra Madre of New Mexico,
extends northwestward across the Colorado far into Utah, where it ends
on the margin of the Great Basin. The rise by this escarpment varies
from 3,000 to more than 4,000 feet. The step from the lowlands to the
highlands which is here called the Mogollon Escarpment is not a simple
line of cliffs, but is a complicated and irregular facade presented to
the southwest. Its different portions have been named by the people
living below as distinct mountains, as Shiwits Mountains, Mogollon
Mountains, Pinal Mountains, Sierra Calitro, etc., but they all rise to
the summit of the same great plateau region.

The upper region, extending to the headwaters of the Grand and Green
Rivers, constitutes the great Plateau Province. These plateaus are
drained by the Colorado River and its tributaries; the eastern and
southern margin by the Rio Grande and its tributaries, and the western
by streams that flow into the Great Basin and are lost in the Great Salt
Lake and other bodies of water that have no drainage to the sea. The
general surface of this upper region is from 5,000 to 8,000 feet above
sea level, though the channels of the streams are cut much lower.

This high region, on the east, north, and west, is set with ranges of
snow-clad mountains attaining an altitude above the sea varying from
8,000 to 14,000 feet. All winter long snow falls on its mountain-crested
rim, filling the gorges, half burying the forests, and covering the
crags and peaks with a mantle woven by the winds from the waves of the
sea. When the summer sun comes this snow melts and tumbles down the
mountain sides in millions of cascades. A million cascade brooks unite
to form a thousand torrent creeks; a thousand torrent creeks unite to