Grand Canyon National Park
Grand Canyon National Park
Natural United States Of America Europe And North America Counties Of Coconino And Mohave In The State Of Arizona

Grand Canyon National Park was created on 26 February 1919 by an act of Congress. First protected in 1893 as a forest reserve in which mining, lumbering and hunting continued to be allowed: upgraded to a game reserve in 1906, giving protection to the wildlife: redesignated a National Monument in 1908.

The park is dominated by the spectacular Grand Canyon: a twisting, 1.5 km deep and 445.8 km long gorge, formed during some 6 million years of geological activity and erosion by the Colorado River on the raised Earth's crust (2.5 km above sea level). It divides the park into the North Rim and South Rim which overlook the 200 m to 30 km wide canyon;the buttes, spires, mesas and temples in the canyon are in fact mountains looked down upon from the rims. Ongoing erosion by the seasonal and permanent rivers produces impressive waterfalls and rapids of washed-down boulders along the length of the canyon and its tributaries. Exposed horizontal geological strata in the canyon span some 2,000 million years of geological history, providing evidence of the four major geological eras, early and late Precambrian, Palaeozoic, Mesozoic and Cenozoic. The early Precambrian strata, known as the Vishnu Schist formation, are devoid of fossils. The first fossil evidence appears in the late Precambrian Bass Limestone with remains of early plant forms. Subsequent strata dating from the Palaeozoic era catalogue the sequence of local history, with both marine and terrestrial fossils demonstrating the periods in the distant past when the whole region was alternately submerged and raised. The Mesozoic era is less well illustrated within the park, but tracks made by early reptiles are found to the east in the Navajo Indian reservation. They are a few fossil remains of mammals from the early Cenozoic.

Altitudinal range provides a variety of climates and habitats, ranging from desert to mountain conditions. The canyon is a vast biological museum stretching through five different life and vegetation zones: Hudsonian on the North Rim plateau with Colorado blue spruce and Rocky Mountain maple;Canadian near the North Rim, with aspen and Ponderosa and forests of Douglas fir, white fir and aspen at 2,500 m;high-altitude Transition (Ponderosa) forests of Pinus ponderosa and gambel oak;upper Sonoran on and below the South Rim with Utah juniper, pinon pine and sagebrush;and the Lower Sonoran down the canyon and at the bottom (desert cacti, rabbitbrush, mesquite, Morman tea and Manzanita).

Over 1,000 plant species have so far been identified from the park. There are 11 plant species listed as threatened in the United States statutes in the park, including Palmer amsonia, goldenweed, plains cactus, scouler catchfly, wild buckwheats, primrose and clute penstemon. In addition, 15 plant species are recommended for consideration as threatened species under the Endangered Species Act.

Concerning the fauna, 76 mammal, 299 bird and 41 reptile and amphibian species have been identified from the park and some 16 fish species inhabit the Colorado River and its tributaries. Rare or threatened birds are listed under the United States Endangered Species Act of 1973.

The park contains more than 2,600 documented prehistoric ruins, including evidence of Archaic cultures (the earliest known inhabitants), Cohonina Indians along the South Rim, and Anasazi Indians on both the South Rim, North Rim, and within the Inner Canyon. Hualapai and Havasupai Indians moved into the canyons at this time, where they remained undisturbed until the Anglo-Americans arrived in 1860. Archaeological remains show the adaptation of human societies to severe climate and physiographic environment.