November 20, 2009

Grand Canyon

Grand canyon

"Grand" does not tell how truly incomprehensible this canyon is. Most people use such words as "marvelous" or "fantastic" but no word is really adequate to describe this amazing wonder of nature. The scene continually changes as light plays off the rocks and clouds, creating shadows and contrasts. The world seems larger here with sunrises, sunsets, and storms taking on an added dimension to match the landscape. The permutations are unceasing, and the moods are without end. This is a land to humble the soul.

Grand Canyon is in the northwest corner of Arizona, close to the borders of Utah and Nevada. The Colorado River, which flows through the canyon, drains water from seven states, but the feature we know as Grand Canyon is entirely in Arizona. Most of Grand Canyon lies within Grand Canyon National Park and is managed by the National Park Service. It was first protected in 1893 as a forest reserve in which mining, hunting and lumbering were permitted; upgraded to a game reserve in 1906, giving protection to the wildlife; and declared a national park on 26 Feb 1919 by Act of Congress. The climate at Grand Canyon is classified as semi-arid (south rim receives 15 inches of precipitation each year, only 8 inches each year reaches the canyon bottom). Many people consider Grand Canyon National Park the world’s premiere geologic landscape and a "geologic wonder". Grand Canyon contains many important geologic resources, including a vast fossil record ranging from Precambrian stromatolites to Ice Age mammal bones and dung found in caves; a potentially active volcanic field in the western Grand Canyon; a geologic history ranging more than 1.7 billion years; and the canyon landscape itself as the greatest example of arid land erosion. Grand Canyon owes its unique shape to the fact that the different rock layers in the canyon walls each respond to erosion in different ways: some form slopes, some form cliffs, some erode more quickly than others. The vivid colors of many of these layers are mainly due to small amount of various minerals, most containing iron, which impart subtle shades of red, yellow or green to the canyon walls. Climate plays an important role, too. If the climate at Grand Canyon were wetter, the planes and trees that grow there would be very different, and the canyon walls might be covered with lush vegetation.

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