The Grand Canyon, created by the Colorado River over a period of 6 million years, is 446 km long, ranges in width from 6 to 29 km and attains a depth of more than 1.6 km. During prehistory, the area was inhabited by Native Americans who built settlements within the canyon and its many caves. The Grand Canyon is more than a great chasm carved over millennia through the rocks of the Colorado Plateau. It is more than an awe-inspiring view. It is more than a pleasuring ground for those that explore the roads, hike the trails, or float the currents of the turbulent Colorado River. This canyon is a gift that transcends what we experience. Its beauty and size humbles us. Its timelessness provokes a comparison to our short existence. In its vast spaces we may find solace from our hectic lives. The Grand Canyon we visit today is a gift from past generations. Take time to enjoy this gift. Sit and watch the changing play of light and shadows. Wander along a trail and feel the sunshine and wind on your face. Attend a ranger program. Follow the antics of ravens soaring above the rim. Listen for the roar of the rapids far below. Savor a sunrise or sunset. As the shadows lengthen across the spires and buttes, time passing into the depths of the canyon, understand what this great chasm passes to us - a sense of humility born in the interconnections of all that is and a willingness to care for this land. We have the responsibility to ensure that future generations have the opportunity to form their own connections with Grand Canyon National Park.
The Grand Canyon is a steep-sided gorge carved by the Colorado River in the United States in the state of Arizona. It is largely contained within the Grand Canyon National Park — one of the first national parks in the United States. President Theodore Roosevelt was a major proponent of preservation of the Grand Canyon area, and visited it on numerous occasions to hunt and enjoy the scenery.A map of the Grand Canyon and surrounding areas, circa 1908. Longstanding scientific consensus has been that the canyon was created by the Colorado River over a six million year period. The canyon is 277 miles (446 km) long, ranges in width from 4 to 18 miles (6.4 to 29 km) and attains a depth of over a mile (1.83 km) (6000 feet). Nearly two billion years of the Earth's geological history have been exposed as the Colorado River and its tributaries cut their channels through layer after layer of rock while the Colorado Plateau was uplifted. The "canyon began in the west, followed by another that formed in the east. Eventually, the two broke through and met as a single majestic rent in the earth some six million years ago. The merger apparently occurred where the river today bends to the west, in the area known as the Kaibab Arch." Before European immigration, the area was inhabited by Native Americans who built settlements within the canyon and its many caves. The Pueblo people considered the Grand Canyon ("Ongtupqa" in Hopi language) a holy site and made pilgrimages to it.[3] The first European known to have viewed the Grand Canyon was García López de Cárdenas from Spain, who arrived in 1540.
The principal consensus among geologists is that the Colorado River basin (of which the Grand Canyon is a part) has developed in the past 40 million years. A recent study places the origins of the canyon beginning some 17 million years ago. Previous estimates had placed the age of the canyon at 5 to 6 million years. The study, which was published in 2008 in the journal Science utilized uranium-lead dating to analyze calcite deposits found on the walls of nine caves throughout the canyon.[6] There is a substantial amount of controversy because this research suggests such a substantial departure from prior widely supported scientific consensus. The result of all this erosion is one of the most complete geologic columns on the planet.The Muddy Colorado River from Navajo Point. The major geologic exposures in the Grand Canyon range in age from the 2 billion year old Vishnu Schist at the bottom of the Inner Gorge to the 230 million year old Kaibab Limestone on the Rim. Interestingly, there is a gap of about one billion years between the stratum that is about 500 million years old and the lower level, which is about 1.5 billion years old. That indicates a period of erosion between two periods of deposition. Many of the formations were deposited in warm shallow seas, near-shore environments (such as beaches), and swamps as the seashore repeatedly advanced and retreated over the edge of a proto-North America. Major exceptions include the Permian Coconino Sandstone, which most geologists interpret as an aeolian sand dune deposit and several parts of the Supai Group. The great depth of the Grand Canyon and especially the height of its strata (most of which formed below sea level) can be attributed to 5,000 to 10,000 feet (1500 to 3000 m) of uplift of the Colorado Plateau, starting about 65 million years ago (during the Laramide Orogeny). This uplift has steepened the stream gradient of the Colorado River and its tributaries, which in turn has increased their speed and thus their ability to cut through rock (see the elevation summary of the Colorado River for present conditions). Weather conditions during the ice ages also increased the amount of water in the Colorado River drainage system. The ancestral Colorado River responded by cutting its channel faster and deeper.
