Molokai consists of two major volcanic principal parts: East Molokai volcanic series and the West Molokai volcanic series.

Reports on the domestic water supply derived from rain caught from roofs and some ground wells. Overall, the island has high aridity, unfavorable geologic structures, continuous deposition of salt spray, and abundant authigenic salts in the lake beds.

Report of the systematic study of the geology and ground-water resources of Lanai and Kahoolawe as part of the geological survey by United States Department of the Interior.