Arizona
(Flag of Arizona)
Capital / Phoenix
Area / 295,254 km²
- Land / 294,312 km²
- Water / 942 km² (0.32%)
- Population / 5,130,632
Introduction
Arizona is a large state in the western United States. It is situated south and east of the Colorado River. It borders are New Mexico, Utah, Nevada, Colorado and California, and it has a long international border with Mexico.
Arizona is best known for its desert landscape with cacti. It is also known for its very hot summers and mild winters.
Aside from the Grand Canyon, a number of other National Forests, Parks, Monuments, and Indian reservations are located in the state.
Historians disagree about the origin of the name "Arizona" and its attachment to the region. Two possible derivations are:
- Spanish words "árida zona" ("arid zone") However, this would be grammatically incorrect because in Spanish, the noun precedes the adjective.
- Two Papago Indian words meaning "place of the young spring"
Canyon
Introduction
A canyon, or gorge, is a valley walled by cliffs.
Most canyons originate by a process of long-time erosion from a plateau level, with a river gradually carving out its valley. Canyons are much more common in arid areas than in wetter areas because weathering has a lesser effect in arid zones. Canyons' walls are often formed of resistant granite.
The word canyon has a Spanish origin (cañón). It is generally used in the United States. The word Gorge is more common in Europe.
Canyons are important for archeology because the cliff shows the layers of the ground.
Sometimes large rivers run through canyons as the result of gradual geologic uplift. The Colorado River and the Snake River in the northwestern United States are two examples of this.
Canyons often form in areas of limestone rock. Limestone is to a certain extent soluble, so cave systems form in the rock.
Two canyons usually attributed as the world's largest are the Grand Canyon and the Copper Canyon in Mexico
Grand Canyon
Introduction
Grand Canyon is an exceptionally deep and steep-walled canyon in northwestern Arizona. It has been excavated by the Colorado River. The Grand Canyon is 446km long, up to 29km large and more than 1500m deep. The entire canyon is extremely beautiful, containing very high buttes and valleys within its main gorge. Spectacular sections of the canyon, and plateau areas on either side of it, are preserved as the Grand Canyon National Park. It receives about four million visitors a year. The Grand Canyon lies on an arid plateau region, between 1500m and 2700m above sea level. This region is sharply eroded, interspersed with old lava flows and hills composed of volcanic debris. The northern of the plateau area is forested and the southwest is sparsely covered with evergreens. Vegetation in the depths of the valley consists principally of desert plants. The climate of the plateau region above the canyon has extremes of both heat and cold. The canyon floor also becomes extremely hot in summer, but seldom frozen in the wintertime.
History
The first European to see the Grand Canyon was the Spanish explorer Francisco Vasquez de Coronado, in February 1540. It has been full explored 3 centuries later because of the inaccessibility of the canyon. A series of expeditions from the US Army surveyed the canyon and the surrounding area since 1850.
Colorado River
Description
The source of the Colorado River is the Grand Lake in Colorado, in the Rocky Mountain National Park. The river flows to the southwest through the state of Colorado, and then runs through national parks in the Colorado Plateau. In southern Utah, the water of the Colorado is restrained by the Glen Canyon Dam forming the Lake Powell. The river then continues west across northern Arizona through the Grand Canyon. On the border of Arizona and Nevada, near Las Vegas, the Hoover Dam forms a reservoir called Lake Mead. From this point the river flows southward, forming the boundary between Nevada and California on and Arizona. The Colorado ends into the Gulf of California in northwestern Mexico.
The Colorado River's major tributaries are Gunnison, Green and San Juan rivers. They are fed by rainfall and melting snow from the high mountains. The lower tributaries of the Colorado add large amounts of sediment giving the characteristic reddish color to the river.
Over thousands of years the river has built up a delta at its mouth. [A delta is an accumulation of sediment or silt that a river deposits where it empties into an ocean]. At one time, the Colorado entered the Gulf of California near the present site of the city of Yuma in Arizona. Because of the growth of the delta, the mouth of the Colorado is now located approximately 100km south of Yuma.
Economic importance
The Colorado River is an important natural resource of the southwestern United States. About two-thirds of the water is used for irrigation, and the rest supplies urban areas or nourishes vegetation along the riverbanks.
During the 20th century, many dams were built on the Colorado and its tributaries. These dams generate electricity, control floods and also store water. Together the dams in the basin can put in store more than 86 milliard cubic meters of water.
The water concentrated at dams, all over the Colorado River, is used to provide hydroelectric power for the region. It totals about 12 milliard kW/h each year, one-sixth of the electricity consumed in Arizona each year.
Dams also control flooding and permit development of land along the river. Some of the reservoirs created by dams have been incorporated into national parks. The Glen Canyon National Recreation Area includes Lake Powell. The Lake Mead National Recreation Area is made up of Lake Mead, formed by Hoover Dam.
History
The Natives of the region who belonged to the Anasazi, constructed elaborate canal and reservoir systems to divert water from the Colorado River and its tributaries. They used the water to irrigate fields of corn, beans, and other crops.
The name "Colorado" comes from a Spanish settlers who had noted its reddish color.
In 1902, the U.S. government began to construct large-scale dams and irrigation systems.