National Park - Photo Album Sediments come from debris eroded from the land.
Water carries varying sizes of debris or dissolves it chemically.
When water slows or cools, particles settle to the bottom of the waterway, sorted by size and weight. Sedimentary rocks form when particles are cemented and bonded together. Hoodoos are carved from the Claron Formation, whose rock was deposited by ancient rivers, streams, and lakes over a period of 20 million years. State shapes are shown for reference. On the Colorado Plateau, the high elevations and mountains create micro-climates where forests may grow surrounded by arid lowlands.