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These photos are from two rafting trips through the length of the Grand Canyon, and more than twenty backpacking trips ranging from three to nine days in length. All are from scanned slides.

The Grand Canyon, located in Arizona, was formed 5-6 million years ago by a combination of the uplifting of the Colorado Plateau, and the Colorado River cutting through the plateau as it rose. The upper layers of the Colorado Plateau are composed mainly of sedimentary rock, which erodes easily.

The Canyon is 277 miles long (446km) and about 5000 feet deep (about one mile) (1524m) at the South Rim, 6000 feet deep (1829m) at the North Rim. It varies in width from 5 miles to 18 miles across (8km to 29km) and average 10 miles across (16km); it is 10 miles wide at the Grand Canyon Village.

Within the Canyon are five of the seven life zones of North America, which is the equivalent of traveling from Mexico to Canada, and accounts for its great biological diversity. Over 1,500 plant, 355 bird, 89 mammalian, 47 reptile, 9 amphibian, and 17 fish species are found in the Park.

The Colorado River is 1450 miles long (2333km), originating in the Rocky Mountains in Colorado and ending in the Gulf of California in Mexico. It averages about 300 feet wide (91m). As it flows through the 277 miles of the Grand Canyon, the elevation falls from 3166 feet (965m) at Lee's Ferry to 1200 feet (366m) at Lake Mead.

More than 160 rapids are encountered along the 277 miles, and they're responsible for most of the 2000 feet elevation decrease of the River. For example, Lava Falls - one of the most dangerous rapids - drops 37 feet during its 900 foot length. The rapids are formed by debris flows from the many side canyons that bring large boulders and other debris into the River during floods. The debris constricts the flow and increases the speed of the river along the rapids.

Overall, the color the Canyon is red, but each layer or group of layers has a distinctive hue: buff and gray, delicate green and pink, and - in its depths - brown, slate gray, and violet.

For more detailed information about the geology of the Grand Canyon: http://www.kaibab.org/geology/gc_geol.htm