Referat The Grand Canyon - Establishment, Geology

The Grand Canyon

Today I want to give you a little impression of the Grand Canyon, I'm sure all of you know it.

1.) Establishment

"Grand Canyon National Game Preserve", established in 1906, became "Grand Canyon National Park" by an Act of Congress in 1919. The Grand Canyon National Park covers 4931 square kilometers in northwestern Arizona. It includes 170 kilometers of the most colorful part of the Grand Canyon of the Colorado River.

2.) Geology

The Colorado River rushes at the bottom of the canyons, about 564 meters above sea level. The sides of the canyons are made of rocks, cliffs, ridges, hills and valleys of every form. Many of the ridges have weather carved lines which make them resemble Chinese temples. Thick forests of blue spruce, fir, oaks as well as Ponderosa pines cover the canyon rim. Deep in the canyon's recesses, the foliage grows sparse and shorter. Pinon pines and juniper growing along the cliffs give way to dry desert scrub on the canyon floor.

The north rim of the Grand Canyon rises about 366 meters feet higher that the south rim. The highest points on the rim are about 2743 meters above sea level.

Most of the 4931 square kilometers of the park are maintained as wilderness. There are three distinct sections of the park; the South Rim, the North Rim and the Inner Canyon. Each section has a different climate as well as different vegetation and different experiences.

The North Rim is the coldest and the wettest. It receives up to 660 millimeters of precipitation a year. The South Rim only receives around 410 millimeters of precipitation a year. The Inner Canyon is the closest to a desert as the lower you descend, the hotter and drier it becomes. The floor of the canyon, approximately 1,6 kilometers below the North Rim, is about 35 degrees hotter than the temperatures above.

The colorful canyon rocks were formed millions of years ago. Their colors change with the changing light of the sun. Many layers of rock have been bared by the constant cutting force of the rushing river. The first layer of rock through which the Colorado River now cuts is black in color and is called Archean. The second layer, called Algonkian, has a brilliant red color. The next layer is a lavender-brown color and is known as Tapeats sandstone. The forth layer, the Devonian layer, consists of small deposits of lavender stone. Above this, the thick Redwall curves along the canyon. Above the Redwall lies 245 meters of red sandstone called the Supai formation. The Hermit shale, another layer of red rock covers this.

On top of the Hermit shale rests the sand colored Coconino sandstone, a pale bank that lies 107 meters below the rim of the canyon. The top layer of the canyon consists of cream and gray colored Kaibab limestone. This limestone forms a rim known as the Kaibab Plateau on the north side of the canyon, and as the Coconino Plateau on the south.

Scientists still haven't agreed on the how's and why's of the creation of the Grand Canyon, but there is always one constant, the Colorado River. It always was and always will be the catalyst for change in the canyon.

3.) Human History

The canyon has also been home to waves of humans. Archaeologists estimate that there may be 50,000 sites below the rim. The Anasazi, who were not the first peoples to live in the canyon, built granaries, houses and temples which can still be seen by hikers and rafters below the rim. The first Spanish expedition into the area in 1540 turned back after 3 days of trying to find a path into the canyon. There is no evidence of Europeans visiting the area again until 1776, more than 200 years later. Joseph Ives, a U.S. explorer who visited the canyon in 1857 declared the region 'altogether valueless' and predicted that his would be 'the last party of whites to visit this profitless locality.'

4.) Wildlife

Because of the canyon's isolation, some species have evolved distinctive forms: a pink rattlesnake made to order to match the canyon's pink sandstone.

Two of the park's most celebrated inhabitants are the Albert squirrel and the Kaibab squirrel. The Kaibab squirrel, which are black with a white bushy tail, only lives on the north rim and the Albert squirrel are found only on the south rim. They shared the same ancestor, the tassel-eared squirrel. Widely separated by the vast canyon, each cousin has evolved into two separate and distinct species.

Other animals that inhabit the park are mountain lions, deer, porcupines, beavers, lizards, and snakes. There are more than 180 different kinds of birds.