GRAND CANYON

an extremely large gorge (= a valley with steep sides) in the US state of Arizona which is a major tourist attraction. The Canyon was created by the Colorado River and is about 1 mile/1.6 kilometres deep, 200 miles/320 kilometres long and 4–18 miles/6–29 kilometres) wide. It has colourful layers of rock, the oldest of which are about 2 billion years old. Grand Canyon National Park was opened in 1919 and was made a World Heritage Site in 1979.