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 feet (4,205 m) [From base it is 33,474 feet (10,203 m)]
Location	Hawaii, USA
Range	Hawaiian Islands
Prominence	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 volcanic peaks that together form the island of Hawaii. It is the tallest mountain in the world when measured from base to peak, its base being some 19,678 feet (5998 m) under the surface of the Pacific Ocean, which would bring its total height to 33,474 feet (10,203 m). In Hawaiian, mauna kea means "white mountain", a reference to the fact that it is regularly snow- or frost-capped during the northern hemisphere winter. Its highest point, Puu Wekiu (one of numerous cinder cones on the summit), is the highest point in the state of Hawaii at 13,796 feet (4,205 m).

After hundreds of thousands of years of building itself up by volcanic activity, the mountain's height is slowly decreasing as its massive weight depresses the Pacific seafloor.

Although snow and ice occur now mostly in the period from November through March, Mauna Kea had permanent (year-round) ice caps during the Pleistocene ice ages (Woodcock et al., 1970). 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.

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. 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 elevation and location of Mauna Kea have made it an important location 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 (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 wekiu bug, which feeds on insects blown up to the cold summit and caught in snow. Studies on the impact of telescopes on wekiu bug populations have been inconclusive, with accusations of overcollecting and bias among the different parties.