Grand Canyon National Park


Creation of the Park

President Theodore Roosevelt, by presidential proclamation, reserved land in the Grand Canyon of Arizona as the Grand Canyon National Monument on January 11, 1908. President Roosevelt stated in the proclamation that the Grand Canyon of Arizona "is an object of unusual scientific interest, being the greatest eroded canyon in the United States, and it appears that the public interest would be promoted by reserving it as a National Monument" (Proclamation No. 794).

On February 26, 1919, Congress dedicated and set apart Grand Canyon National Park. Over the years the park has been enlarged and its boundaries revised, most recently on January 3, 1975, when Congress recognized "that the entire Grand Canyon, from the mouth of the Paria Riverto the Grand Wash Cliffs, including tributary side canyons and surrounding plateaus, is a natural feature of national and international significance."

Ecology & Geology

The great biological diversity of the park includes examples of five of the seven life zones and elements of three of the four deserts in North America (the Great Basin, Sonoran, and Mojave).

The park serves as an ecological refuge, with relatively undisturbed remnants of dwindling ecosystems (such as boreal forest and desert riparian communities), and numerous rare, endemic, or specially protected (threatened/endangered) plant and animal species.

The Grand Canyon is the "greatest eroded canyon in the United States." It is considered one of the finest examples in the world of arid-land erosion. The Grand Canyon is neither the world's longest nor deepest canyon, but its volume is immense, averaging 4,000 feet deep for its entire length of 277 miles, 6,000 feet deep at its deepest point, and 18 miles wide at its widest.

The geologic record of the Grand Canyon is particularly well-exposed and includes a rich and diverse fossil record. The canyon also contains a great diversity of geological features and rock types. Numerous caves in the park contain extensive and significant geological, paleontological, archeological, and biological resources.

Before the construction of Glen Canyon Dam, spring run-off in the Colorado River was much more torrential, altering sand bars, scouring backwater lagoons, and washing away the riverbank's vegetation. The effect is similar to that of a forest fire, which ecologists now realize is important to the health of many types of forests.

Before construction of the dam, the Colorado River would run hot and cold according to the season. During the summer, water temperatures would reach into the 900s, just right for spawning native fish. The water is now much colder, never getting above 500, seriously damaging native fish populations. Of the eight native fish that once lived in the Grand Canyon, three have disappeared from canyon waters. Of the remaining five, two are on the endangered species list. The colder waters have become welcome habitat for introduced trout, which does makes the few anglers who can make it down to the river happy.

In March 1996, the Department of Interior let loose a huge flood from the dam in an attempt to mimic natural patterns of flooding. Although the Department of Interior was quick to pronounce the flooding a success, many scientists and environmentalists have taken a wait-and-see attitude. The flood could have been a case of too little too late. The flood did create 55 new sandbars, which could possibly help the reproduction of native fish. However, it did not flush away non-native fish, as predicted. And of course, the one time flood did nothing to alter the temperature of the water in the summer. By washing away bankside vegetation, the flood opened the way for invasion by non-native vegetation, especially the tamarisk tree. Without a natural annual flood, the spread of these non-natives will continue unabated except by expensive hand-pulling.

Six research natural areas have been designated in the park (8,845 acres total) to provide opportunities for nondestructive research in areas relatively uninfluenced by humans.

A national natural landmark occurs partially within the park, which encourages recognition and protection of the ponderosa pine habitat of the Kaibab squirrel a classic example of the process of variation through geographic isolation.

Other Resources

The Grand Canyon Field Institute is the seminar arm of the Grand Canyon Association, which is the non-profit cooperating association for the national park. Many of their environmental programs are taught by Park Service rangers and archaeologists. For information write the Institute at P.O. Box 399, Grand Canyon, AZ 86023, or call 520-638-2485.


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