Geology%20of%20Island%20of%20Maui

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• Geology of Island of Maui
• Island of Maui formed of two large shield
  volcanoes
• West Maui Shield Volcano, age 1.97 to 0.39 Ma,
  Extinct Volcano
• has rocks from all three sub aerial eruptive
  phases shield, postshield alkalic cap, and
  rejuvenation
• East Maui Shield Volcano, 1.1 Ma to present,
  Active Volcano
• has rocks from the late shield (rare) and
  postshield alkalic cap (most of the volcanos
  modern surface)
• is still in the postsheild alkalic cap stage
• includes Haleakala crater - an erosional feature
  modified by later eruptions, Last erupted in 1790.

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Ancient Island of Maui Nui

• Maui Nui -Greater Maui was geologically a very
  large island, now spilt into four smaller
  islands.
• The four islands of Maui, Molokai Mo Mauilokai,
  Lanai, and Kahoolawe formed a single landmass
  in the past called Maui Nui (Greater Maui) formed
  of 6 or 7 shield volcanoes. It included Penguin
  Bank, now a submerged shelf between Molokai and
  Oahu.
• Around 2 million years ago, volcanoes on all of
  these islands as well as the Koolau on Oahu
  were in their shield building stage, which means
  there were 7 to 9 active shield volcanoes at the
  same time.

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About 300,000 to 400,000 years ago, Maui Nui,
which grew from west to east. The Maui Nui
subsided to form two islands, one consisting of
Penguin Bank, Moloka'i, and Lanai, and the other
consisting of Maui and Kaho'olawe. Kaho'olawe
then separated from Maui, and finally Lanai
separated from Moloka'i, both within the last
100,000 to 200,000 years. Penguin Bank probably
submerged within the last several hundred
thousand years. During the last glacial maximum
(LGM), about 21,000 years ago, the Hawaiian
Islands of Maui, Lanai, and Molokai were
interconnected by limestone bridges, creating a
super-island known as Maui-Nui. Approximately 120
m of sea-level rise during the Holocene
Transgression flooded, and then drowned, these
bridges separating the islands by inter-island
channels.With continued subsidence at the
present-day rates, East Maui (Haleakala) and West
Maui will become separate islands in about 15,000
years.
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Hawaiian Islands
Oahu
Molokai
Maui
Penguin Bank
Lanai
Kahoolawe
Hawaii
Above Sea level
Below Sea level
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Island of Maui Nui 1,200,000 years ago
Oahu
Hawaii
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Island of Maui Nui
Splitting act of the Island of Maui Nui Island
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Molokai
Maui
Penguin Bank
Lanai
Kahoolawe
Island of Maui Nui
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Island of Maui Nui
Maui Nui probably had a maximum size of about
11,000 square km (6,200 square miles), some 4,000
square km (2,150 square miles) larger than
present-day Hawaii.
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Island of Maui
West MauiVolcano and Caldera
East MauiVolcano
Haleakala
Rift Zones
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Rift Zones
West Maui volcano, in the lower left, is 1800
meters high (5900 feet) and is considered
extinct. East Maui volcano, rises to an elevation
of 3200 meters (10,500 feet).
West Maui
East Maui
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Shield
West Maui
East Maui
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Island of Maui
East Maui Shield Volcano Facts Location Lat
20.7180 North Long 156.2540 WestElevation Above
Sea Level3,055 m, 10,023 ft Area 1,470 km2 , 570
mi2 (77 of Island of Maui) Volume 30,000 km3
7,200 mi3 - 97 of volume is below sea
level Last erupted 1790
Radial Drainage
Haleakala Crater formed between 145,000 and
120,000 years ago. It is a large erosional valley
at the summit of East Maui Volcano.