Grand Canyon

The Grand Canyon is a huge gorge carved by the Colorado River in Arizona, US. It also extends to parts of Nevada. It is largely contained within the Grand Canyon National Park -- one of the first national parks in the United States.

The Grand Canyon is one of the world’s most spectacular example soil erosion. Scientists estimate Grand Canyon began forming 6 million years ago with the downward cutting (erosion) of the Colorado River, which flows through the Canyon. The erosion still continues by the powerful forces of the river, rain, snow, heat, frost and wind.

Why should I be aware of this?

• The great biological diversity of the Grand Canyon park includes examples of five of the seven life zones.
• It contains elements of three of the four deserts in North America (the Great Basin, Sonoran, and Mojave).
• The Grand Cayon 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 species and endangered species) 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 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.
• In 1975, the US Congress recognized "that the entire Grand Canyon is a natural feature of national and international significance.

All about the Grand Canyon

• The Grand Canyon National Park encompassed 1,218,375 acres on the Colorado Plateau in northwestern Arizona.
• The Grand Canyon is 277 miles long, up to 18 miles wide and 5000 feet deep.
• The Grand Canyon cuts through the Colorado Plateau that is between 5000 and 9000 feet above sea level.

The creation of Grand Canyon

The Grand Canyon began forming six million years ago with the beginning erosion of the Colorado River. The Grand Canyon has been created in general because of the downward cutting of the Colorado River which flows thru the canyon. Another factor that has caused the Grand Canyon to form is the Kaibab Plateau (which is the north rim) is about 1200 feet higher then the Coconino Plateau (which is the southern rim). Water from the northern plateau flows into the canyon creating stream and eroding the earth, but the stream from the southern plateau flows in a southern direction away from the north therefore the canyon never fills with water it just continues to erode.

Grand Canyon and the environment

• The Grand Canyon contains several major ecosystems.
• The Grand Canyon hosts five of the seven life zones and three of the four desert types in North America. If you were to travel from Mexico to Canada you would see the same five life zones represented in the Grand Canyon.
• Over 1,500 plant, 355 bird, 89 mammalian, 47 reptile, 9 amphibian, and 17 fish species are found in the park.
• Since the entire canyon has little soil there is very little vegetation is seen except on parts of the rims. The northern rim is partly forested with evergreens. In the depths of the valley very little grows except desert plants and Spanish bayonet.

Environmental concerns

In March 2008, the US government initiated a manmade flood to help restore the Grand Canyon's ecosystem. This was not the first time it had happened. The first manmade flood was introduced in 1996 followed by another in 2004 as part of efforts to mimic natural cycles on the river. The 1996 flood did create 55 new sandbars, which helped the reproduction of native fish. However, it did not flush away non-native fish, as predicted. And of course, the flood did nothing to alter the temperature of the water in the summer. And by washing away bankside vegetation, the flood opened the way for invasion by non-native vegetation, especially the tamarisk tree.

• 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 were just right for spawning native fish. The water is now much colder, 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 construction of the dam helped speed the extinction of four fish species and push two others, including the endangered humpback chub, near the edge.

References

• Grand Canyon National Park Environment
• Grand Canyon facts
• Feds release flood in Grand Canyon
• Did you know how Grand Canyon became a grand canyon? :National Geographic]