The Grand Canyon is a steep-sided valley imprinted by the Colorado stream in the United States in the state of Arizona. It is mainly contained within the impressive Canyon National Park, one of the first countrywide parks in the United States. Leader Theodore Roosevelt was a major proponent of protection of the Grand Canyon area, and visited it on plentiful occasions to stalk and enjoy the panorama.
The majestic Canyon is 277 miles (446 km) extended, up to 18 miles (29 km) wide and attains a deepness of over a mile (1.83 km) (6000 feet). Almost two billion years of the Earth's physical history have been uncovered as the Colorado River and its tributaries slash their channels through layer after layer of sway while the Colorado Plateau was uplifted. While the exact geologic process and timing that shaped the Grand Canyon are the topic of debate by geologists, recent evidence suggests the Colorado River established its course through the canyon at least 17 million years ago. Since that time, the Colorado River continued to erode and form the canyon to the peak we see it at today
Before European colonization, the region was occupied by Native Americans who built settlements within the canyon and its numerous caves. The Pueblo people considered the Grand Canyon ("Ongtupqa" in Hopi language) a holy site and made pilgrimages to it. The first European known to have viewed the Grand Canyon was García López de Cárdenas from Spain, who arrived in 1540.
The Grand Canyon is a huge crack in the Colorado Plateau that exposes uplifted Proterozoic and Paleozoic strata, and is also one of the six distinct physiographic sections of the Colorado flat terrain zone. It is not the deepest canyon in the world (Kali Gandaki Gorge in Nepal is far deeper), nor the widest (Capertee Valley in Australia is about 0.6 mi/1 km wider and longer than Grand Canyon); however, the Grand Canyon is known for its visually overwhelming size and its intricate and colorful landscape. Geologically it is significant because of the thick sequence of ancient rocks that are beautifully preserved and exposed in the walls of the canyon. These rock layers record much of the early geologic history of the North American continent.
The Colorado River sink has urbanized in the history 40 million years. A new learn places the origins of the canyon beginning various 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 the journal Science in 2008, used uranium-lead dating to analyze calcite deposits found on the walls of nine caves throughout the canyon. There is a substantial amount of controversy because this research suggests such a substantial departure from prior widely supported scientific consensus.
The effect of all this attrition is one of the most whole geologic columns on the earth.
The main geologic exposures in the Grand Canyon array in age from the TWO billion year old Vishnu Schist at the base of the inside Gorge to the 230 million year old Kaibab mineral on the Rim. There is a break of about 1 billion years between the layer that is about 500 million years aged and the lower level, which is about 1.5 billion years old. This large unconformity indicates a era of erosion between two periods of declaration