The Grand Canyon is a steep-sided canyon carved by the Colorado River in the United States in the state of Arizona, and is also one of the 19 distinct physiographic sections of the Colorado Plateau province. 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.