|
The Grand Hotel |
Grand Canyon Rates |
 |
Highway 64
Grand Canyon AZ 86023 US
|
|
Let the
Grand Hotel Be Your Home Base During
Your Canyon Visit. Its Unique Atmosphere
Will Enrich and Enhance Your Grand
Canyon Experience. Located Just |
|
|
|
The Grand Canyon cuts steeply through an
arid plateau region that lies between about 1500 and 2700 m (about 5000
and 9000 ft) above sea level. This region, although lacking year-round
streams in recent years, is sharply eroded, showing such characteristic
forms as buttes; it is interspersed with old lava flows, hills composed
of volcanic debris, and intrusions of igneous rock. The plateau area has
a general downward slope to the southwest and in its upper reaches is
sparsely covered with such evergreens as juniper and piņon. Parts of the
northern rim of the canyon are forested. Vegetation in the depths of the
valley consists principally of such desert plants as agave and Spanish
bayonet. In general the entire canyon area has little soil. The climate
of the plateau region above the canyon is severe, with extremes of both
heat and cold. The canyon floor also becomes extremely hot in summer,
but seldom experiences frost in the wintertime.
The Grand Canyon has been sculpted in
general by the downward cutting of the Colorado River, which flows
through the canyon's lowest portions. Other factors have also played a
part. The Kaibab Plateau, which forms the northern rim of the canyon, is
about 365 m (about 1200 ft) higher than the Coconino Plateau, which
forms the southern rim. Water from the northern side has flowed into the
canyon, forming tributary valleys, while the streams of the southern
plateau flow away in a southerly direction without carving valleys in
the canyon walls. The underlying rock beds also have a southwestern
slant, with the result that groundwater from the north finds its way
into the canyon, but water from the south does not. In the entire canyon
region, the rocks have been broken by jointing and faulting, and
fractures in the rocks resulting from these processes have contributed
to the rapid erosion of the gorge.
The Grand Canyon is of relatively recent
origin; apparently the river began its work of erosion about six million
years ago. Coupled with the downward cutting of the river has been a
general rising or upwarping of the Colorado Plateau, which has added its
effect to the action of the river.
Although the canyon itself is of
comparatively recent origin, the rocks exposed in its walls are not.
Most of the strata were originally deposited as marine sediment,
indicating that for long periods of time the canyon area was the floor
of a shallow sea.
In a typical section of the canyon,
toward its eastern end, nine separate rock layers can be seen, piled
vertically like a stack of pancakes. The topmost layer is a limestone,
the Kaibab limestone. Below this layer is a thick deposit of sandstone,
called the Coconino sandstone, and below that a layer of soft, shaly
rock known as the Hermit shale. Still lower is a series of shales and
sandstones interbedded with each other, collectively termed the Supai
formation. The fossils found in the Supai and the rocks above it suggest
that these rocks were all deposited in the Permian Period, at the end of
the Paleozoic Era, from 225 million to 280 million years ago. However,
the Supai may be slightly older still. Next comes a deposit of light
gray-blue limestone, the Redwall limestone, which in many places has
been colored red by seepage from the Supai beds above. The Redwall is
152 m (500 ft) thick and is easily identified because of the prominent
sheer cliffs that it forms in the canyon walls. This layer has been
identified as belonging to the Mississippian Period (360 million to 330
million years ago). A thin layer of sandstone, the Temple Butte, beneath
the Red wall, gives evidence of having originated in the Devonian Period
(410 million to 360 million years ago). The next three rock layers,
consisting of the brown Muav limestone, the green Bright Angel shale,
and the Tapeats sandstone, all belong to the Cambrian Period (570
million to 500 million years ago), at the dawn of the Paleozoic Era.
Beneath these layers, at the bottom of the canyon, are the most ancient
rocks of all, Precambrian schists and gneisses, from half a billion to a
billion years old.
|
