Everything about Mauna Kea totally explained
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 . Mauna Kea is the tallest mountain in the world when measured from base to summit, since its base is located on the seafloor about beneath the surface of the
Pacific Ocean, bringing its total height to about . In the
Hawaiian language,
mauna kea means "white mountain", a reference to its summit being regularly snow-capped during the Northern Hemisphere winter.
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 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.
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 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 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.
Astronomy
The summit of Mauna Kea is considered to be one of the best astronomical sites in the world. For this reason it's 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's 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's 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's 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.
Further Information
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