Mauna Kea
From Wikipedia, the free encyclopedia
| Mauna Kea | |
|---|---|
 Mauna Kea with its seasonal snowcap, viewed from Kohala Mountain |
|
| Elevation | 13,796 feet (4,205 m) (from base to summit: 33,000 ft (10,000 m)) |
| Location | Hawaii, USA |
| Range | Hawaiian-Emperor seamount chain |
| Prominence | 13,796 ft (4,205 m) Ranked 15th |
| Coordinates | Coordinates: |
| Topo map | USGS Mauna Kea |
| Type | Shield volcano |
| Volcanic arc/belt | Hawaiian-Emperor seamount chain |
| 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. Pu'u Wekiu, one of numerous cinder cones on the summit plateau, is the highest point in the state of Hawaii at 13,796 feet (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 about 19,000 feet (5,800 m) beneath the surface of the Pacific Ocean, bringing its total height to about 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.
Contents |
[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 slowly 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 feet (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 (1 m) 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 5,200 and 8,000 feet (1,600 and 2,400 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 1,500 and 5,200 feet (450-1,600 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 1990s, much of this land is idle or used for eucalyptus farming for wood pulp, cattle grazing, or small-scale farming.
[edit] Astronomy
The summit of Mauna Kea is considered to be one of the best astronomical sites in the world. For this reason it is home to many of the world's leading astronomical observatories. The summit is above approximately 40% of Earth's atmosphere and 90% of the water vapor, allowing for exceptionally clear images of the night sky. 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. The low population density of the Island of Hawaii means that there is little light pollution from man-made sources. All of these factors have made Mauna Kea an ideal location for state-of-the-art astronomy.
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 now home to over a dozen telescopes. Native Hawaiian groups have protested that construction of additional telescopes would cause considerable environmental damage and further desecrate a site that they consider sacred. 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 to the summit by updrafts. Studies on the impact of telescopes on wēkiu bug populations have been inconclusive, with accusations of over-collecting and bias among the different parties. Some mercury spills and sewage dumps have also been reported at the existing telescopes; these are of particular concern because of the unique and otherwise-pristine underground water systems in the area.
[edit] See also
- Mountain peaks of the United States
- Mauna Loa
- Keck telescopes
- Gemini Observatory
- Subaru (telescope)
- United Kingdom Infrared Telescope
- Canada-France-Hawaii Telescope
- Submillimeter Array
- Volcanic Seven Summits
- Kamakahukilani
[edit] References
- 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.
[edit] External links
- Cultural Information Site on Mauna Kea
- Clash between Telescope Develpment and Kanaka Maoli Culture
- USGS page about Mauna Kea
- Global Volcanism Program
- Photos of Mauna Kea from "A Gentle Rain of Starlight: The Story of Astronomy on Mauna Kea" by Michael J. West. ISBN 0-931548-99-3.
|
|||||
