It was formed in two volcanic phases during the
Pleistocene epoch of the
Quaternary period in the
Cenozoic Era. The first formed the broad
tholeiitic shield volcano of West Molokaʻi that ended 1.89 million years ago. The second volcanic phase produced postshield
alkalic volcanics 1.76 million years ago. There is no evidence for a rejuvenated phase of the West Molokaʻi Volcano, whilst the East Molokaʻi Volcano does. West Molokaʻi overlaps the western flank of
East Molokaʻi Volcano, a much larger shield volcano comprising two-thirds of Molokaʻi. Two distinct rift zones are present on the western flank of the volcano, forming a v shape. A third rift zone possibly extended eastward towards the modern day East Molokaʻi Volcano. A collapse occurred around (uncertain) years ago on the eastern/north eastern flank of the volcano and lava flows from East Molokaʻi had filled in the open space, connecting the two volcanoes above surface (also known as the Molokaʻi Saddle). The cliffs of the eastern side of West Molokaʻi is the only remaining evidence for this land slip. Keep note that the West Molokaʻi slip is completely separate from the much larger slip of the East Molokaʻi Volcano. ==References==