The Grand Canyon is an absolutely massive, steep canyon carved by the Colorado River, easily visible to the naked eye even from earth orbit. It is located in Arizona
* 277 miles (446 km) long
* up to 18 miles (30 km) wide
* deepest point – 1,800 meters [ 6,000 feet , over a mile!]
Two billion years of 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. While the specific geologic processes and timing that formed the Grand Canyon are the subject of debate by geologists, recent evidence suggests that 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 its present-day configuration.
For thousands of years, the area has been continuously inhabited by Native Americans who built settlements within the canyon and its many caves. The Pueblo people considered the Grand Canyon (“Ongtupqa” in the 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.
1869 – Major John Wesley Powell and the Grand Canyon
Powell leads a scientific expedition down the Colorado River and through the Grand Canyon – provides evidence of Earth’s very long existence.
“Lost in the Grand Canyon” – PBS series about Jown Wesley Powell’s Colorado River journey. It includes a timeline, maps, and program information. http://www.pbs.org/wgbh/amex/canyon/