Ritchey Crater is a crater in the Coprates quadrangle on Mars, located at 28.8° South and 51° West. It is 79 km in diameter and was named after George W. Ritchey, an American astronomer (1864-1945).
Ritchey Crater is interesting to scientists because it displays several different layers. A dark layer at the top forms a cap rock that protects the underlying layers from erosion. Under this hard, dark layer is a softer, light-toned rock, that breaks into small boulders. The layers might be formed of volcanic ash, lake or stream deposits, or sand dunes.