West Molokai Volcano, sometimes called Mauna Loa for the

census-designated place A census-designated place (CDP) is a concentration of population defined by the United States Census Bureau for statistical purposes only. CDPs have been used in each decennial census since 1980 as the counterparts of incorporated places, such ...

, is an extinct

shield volcano A shield volcano is a type of volcano named for its low profile, resembling a warrior's shield lying on the ground. It is formed by the eruption of highly fluid (low viscosity) lava, which travels farther and forms thinner flows than the more v ...

comprising the western half of

Molokai Molokai , or Molokai (), is the fifth most populated of the eight major islands that make up the Hawaiian Islands, Hawaiian Islands archipelago in the middle of the Pacific Ocean. It is 38 by 10 miles (61 by 16 km) at its greatest length an ...

island in the

U.S. state In the United States, a state is a constituent political entity, of which there are 50. Bound together in a political union, each state holds governmental jurisdiction over a separate and defined geographic territory where it shares its sover ...

Hawaii Hawaii ( ; haw, Hawaii or ) is a state in the Western United States, located in the Pacific Ocean about from the U.S. mainland. It is the only U.S. state outside North America, the only state that is an archipelago, and the only stat ...

Geology

It was formed in two volcanic phases during the

Pleistocene epoch The Pleistocene ( , often referred to as the ''Ice age'') is the geological epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was finally confirmed in ...

of the

Quaternary The Quaternary ( ) is the current and most recent of the three periods of the Cenozoic Era in the geologic time scale of the International Commission on Stratigraphy (ICS). It follows the Neogene Period and spans from 2.58 million years ...

period in the

Cenozoic Era The Cenozoic ( ; ) is Earth's current geological era, representing the last 66million years of Earth's history. It is characterised by the dominance of mammals, birds and flowering plants, a cooling and drying climate, and the current configura ...

. The first formed the broad

tholeiitic The tholeiitic magma series is one of two main magma series in subalkaline igneous rocks, the other being the calc-alkaline series. A magma series is a chemically distinct range of magma compositions that describes the evolution of a mafic magma i ...

shield volcano of West Molokai that ended 1.89 million years ago. The second volcanic phase produced postshield

alkalic Alkalinity (from ar, القلوي, al-qaly, lit=ashes of the saltwort) is the capacity of water to resist acidification. It should not be confused with basicity, which is an absolute measurement on the pH scale. Alkalinity is the strength of ...

volcanics 1.76 million years ago. There is no evidence for a rejuvenated phase of the West Molokai Volcano, whilst the East Molokai Volcano does. West Molokai overlaps the western flank of

East Molokai Volcano The East Molokai Volcano, sometimes also known as Wailau for the Wailau valley on its north side, is an extinct shield volcano comprising the eastern two-thirds of the island of Molokai in the U.S. state of Hawaii. Description The East Molokai ...

, a much larger shield volcano comprising two-thirds of Molokai. Two distinct rift zones are present on the western flank of the volcano, forming a v shape. A third rift zone possibly exented eastward towards the modern day

. A collapse occurred around (uncertain) years ago on the eastern/north eastern flank of the volcano and lava flows from East Molokai had filled in the open space, connecting the two volcanoes above surface (also known as the Molokai Saddle). The cliffs of the eastern side of West Molokai is the only remaining evidence for this land slip. Keep note that the West Molokai slip is completely separate from the much larger slip of the East Molokai Volcano.

References

External links

* {{Hawaiian volcanism Volcanoes of Maui Nui Landforms of Molokai Shield volcanoes of the United States Hotspot volcanoes Polygenetic volcanoes Pleistocene shield volcanoes Pleistocene Oceania Cenozoic Hawaii Extinct volcanoes of the United States