Mauna Kea

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Mauna Kea
Mauna Kea on the Big Island of Hawaii with a light dusting of snow. Viewed from Kohala Mountain
Elevation	13,796 ft (4,205 m) [ from base to summit, over 33,000 ft (10,000 m) ]
Location	Hawaii, USA
Range	Hawaiian Islands
Prominence	13,796 ft (4,205 m) Ranked 15th
Coordinates	19°49′15.7″N, 155°28′06.0″W
Topo map	USGS Mauna Kea
Type	Shield volcano
Age of rock	0.4 Ma
Last eruption	~2460 BC ± 100 years

Mauna Kea is a dormant volcano in the Hawaiian Islands, one of five volcanoes which together form the island of Hawaii. Puu Wekiu, one of numerous cinder cones on the summit plateau, is the highest point in the state of Hawaii at 13,796 ft (4,205 m). Mauna Kea is the tallest mountain in the world when measured from base to summit, since its base is located on the seafloor some 20,000 ft (6,000 m) beneath the surface of the Pacific Ocean, bringing its total height to well over 33,000 ft (10,000 m). In the Hawaiian language, mauna kea means "white mountain", a reference to its summit being regularly snow-capped during the Northern Hemisphere winter.

1 Geology
2 Climatic Zones and Biomes
3 Astronomy
4 See also
5 References
6 External links

[edit] Geology

Mauna Kea is in the post-shield stage of volcanic evolution, having made the transition from the shield stage before about 200,000 to 250,000 years ago. At that time, its appearance was probably quite similar to that of its neighbor Mauna Loa today, a smooth shield volcano with a large summit caldera. Following the transition, eruptions became more explosive in character, resulting in the formation of numerous overlapping cinder cones which eventually filled and completely obscured the caldera. These cinder cones now form the peaks at the summit of Mauna Kea, with several of them exceeding 13,500 ft (4,100 m) in elevation. After several hundred thousand years of building itself up by volcanic activity, the mountain's height is slowly decreasing now as its massive weight depresses the Pacific seafloor beneath it.

The summit of Mauna Kea was entirely covered by a massive ice cap during the Pleistocene ice ages. The summit shows evidence of four periods of glaciation over the last 200,000 years, the last ending about 11,000 years ago, when the most recent ice age finished. The dense rock at the noted adz quarry near the summit is believed to have been formed when lava erupted under a glacier.

[edit] Climatic Zones and Biomes

The summit plateau of Mauna Kea is entirely above timberline, with a landscape of mostly bare rock with patches of alpine tundra. Snowfall often occurs at elevations above 11,000 ft (3,400 m) during the period from November through March. During particularly cold and wet winters (usually linked to La Niña), a snowpack several feet deep may remain in the summit region above 13,000 ft (4,000 m) for weeks or months, permitting skiing and other snowplay activities on the slopes of the cinder cones.

Between 5200 and 8000 feet (1600 and 2400 m) is a band of ranch land, which was formerly koa-mamane forest but has been almost entirely converted to pasture. This area has suffered from heavy infestations of gorse, an invasive species in Hawaii. Most of the north and west slopes are also pasture. The palila, an endangered finch-like honeycreeper, feeds almost exclusively on mamane seeds and lives in mamane-naio forest on the west slope. Large numbers of feral sheep inhabit the upper elevations, and have had a severe impact on the native vegetation.

The windward (eastern) slopes are covered in rain forest between about 1500 and 5200 feet (450-1600 m) elevation. Below this are extensive agricultural lands that formerly included vast areas of sugar cane. With the collapse of the sugar industry in the 1990's, much of this land is idle or used for eucalyptus farming for wood pulp, cattle grazing, or small-scale farming.

[edit] Astronomy

The elevation and location of Mauna Kea have made it an important site for atmospheric and astronomical observations. The summit is above approximately 40% of Earth's atmosphere and 90% of the water vapor, allowing for exceptionally clear images. Additionally, the peak is well above the inversion layer, allowing up to 300 clear nights per year. Also, at 20°N latitude, much of both the northern and southern skies are visible. The fact that it is a shield volcano has meant that road transportation to the summit is relatively easy. All of these factors have made Mauna Kea a prime target for state-of-the-art astronomy, and the summit is home to many different observatories.

Construction of telescopes on Mauna Kea has been a source of controversy in recent years. Due to the qualities listed above, it is a highly favored location and the summit area is becoming crowded. Native Hawaiian groups have protested that construction of additional telescopes, which involves considerable environmental damage in the form of grading and compacting cinder cones, is affecting sacred sites. They consider that the summit of Mauna Kea is the home of the snow goddess, Poliahu. In addition, the summit area is home to a unique insect, the wēkiu bug, which feeds on insects blown up to the cold summit and caught in snow. Studies on the impact of telescopes on wēkiu bug populations have been inconclusive, with accusations of overcollecting and bias among the different parties.

[edit] See also

[edit] References

Mauna Kea view from Kohala

Macdonald, Gordon A., Agatin T. Abbott, and Frank L. Peterson. 1983. Volcanoes in the Sea, 2nd edition. University of Hawaii Press, Honolulu. 517 p.
Woodcock AH, Furumoto AS, Woollard GP (1970). "Fossil ice in hawaii?". Nature 226 (5248): 873. PMID 16057558.