The Grand Canyon, located in Grand Canyon National Park, is an incredible, inconceivable abyss, formed from layer upon layer of different rocks, easily distinguished by colour. Each layer contains clues to the past with its own fossil record. The formation of the canyon has yet to be conclusively determined, with experts unable to agree exactly how it came to exist as it is. The canyon is over a mile deep, ranges from 4 to 18 miles (6 to 30 kilometres) in width and is 277 miles (446 kilometres) long.