The Moenkopi Dormitory is named after the Moenkopi Formation. The Moenkopi Formation formed during the warm, semi-arid early Triassic Period and is divided into layers. This formation is 690-1000 feet thick and made up of silt and sand deposited on coastal plains and tidal flats and in a short-lived arm of the ocean that covered the region. Some beds within the Moenkopi Formation show water ripple marks and mud cracks.