Nearby to Four Corners Monument, and actually used during the original survey of the monument, is the monumental geological feature of Ship Rock. It is located in northwestern New Mexico, near the town of Ship Rock on the Navajo Nation. It is also known as Tsé Bit'a'í, or "the winged rock" in the native Navajo language.
Ship Rock is the volcanic remnant, or volcanic neck, of a prehistoric volcano that erupted ~30 million years ago. Ship Rock intruded within the much older Mancos Shale, a Cretaceous age (~90 million years old) formation made up of mostly claystone and siltstone with minimal amounts of sandstone and limestone that formed on the bottom of the Interior Cretaceous Seaway that once dominated the central portion of North America.