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Tuesday, July 19, 2011

Haleakalā

Haleakalā or the East Maui Volcano, is a massive shield volcano that forms more than 75% of the Hawaiian Island of Maui. The western 25 % of the island is formed by the West Maui Mountains.



Early Hawaiians applied the name Haleakalā ("house of the sun") to the general mountain. Haleakalā is also the name of a peak on the south western edge of Kaupō Gap. In Hawaiian folklore, the depression at the summit of Haleakalā was home to the grandmother of the demigod Māui. According to the legend, Māui's grandmother helped him capture the sun and force it to slow its journey across the sky in order to lengthen the day.

The tallest peak of Haleakalā, at 10,023 feet (3,055 m), is Puʻu ʻUlaʻula (Red Hill). From the summit one looks down into a massive depression some 11.25 km (7 mi) across, 3.2 km (2 mi) wide, and nearly 800 m (2,600 ft) deep. The surrounding walls are steep and the interior mostly barren-looking with a scattering of volcanic cones.



Until recently, East Maui Volcano was thought to have last erupted around 1790, based largely on comparisons of maps made during the voyages of La Perouse and George Vancouver. Recent advanced dating tests, however, have shown that the last eruption was more likely to have been in the 17th century. These last flows from the southwest rift zone of Haleakalā make up the large lava deposits of the Ahihi Kina`u/La Perouse Bay area of South Maui. In addition, contrary to popular belief, Haleakalā "crater" is not volcanic in origin, nor can it accurately be called a caldera (which is formed through when the summit of a volcano collapses to form a depression). Rather, scientists believe that Haleakalā's "crater" was formed when the headwalls of two large erosional valleys merged at the summit of the volcano. These valleys formed the two large gaps — Koʻolau on the north side and Kaupō on the south — on either side of the depression.

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