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The geologic secrets of Lake Mead

As the climate crisis continues to affect the American West, sunken boats and human remains aren't the only surprises to be revealed by record-low water levels at Lake Mead. Sedimentary rocks that hadn't been seen since the ...

'Crowns of the forest': Indonesian helps orchids bloom again

Orchids in hand and a bamboo ladder on his shoulder, farmer Musimin scans the forest at the foot of Indonesia's most active volcano to point out clusters of the indigenous flowers he has been salvaging for years.

Glacier melting on Kamchatka contributed to sea rise

Scientists have quantified the glacier mass loss on the Kamchatka Peninsula; the accelerated loss in the region since the turn of the millennium is likely to increase in the short term.

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Volcano

A volcano is an opening, or rupture, in a planet's surface or crust, which allows hot, molten rock, ash, and gases to escape from below the surface. Volcanic activity involving the extrusion of rock tends to form mountains or features like mountains over a period of time. The word volcano is derived from the name of Vulcano island off Sicily. In turn, it was named after Vulcan, the Roman god of fire.

Volcanoes are generally found where tectonic plates are diverging or converging. A mid-oceanic ridge, for example the Mid-Atlantic Ridge, has examples of volcanoes caused by divergent tectonic plates pulling apart; the Pacific Ring of Fire has examples of volcanoes caused by convergent tectonic plates coming together. By contrast, volcanoes are usually not created where two tectonic plates slide past one another. Volcanoes can also form where there is stretching and thinning of the Earth's crust (called "non-hotspot intraplate volcanism"), such as in the African Rift Valley, the Wells Gray-Clearwater volcanic field and the Rio Grande Rift in North America and the European Rhine Graben with its Eifel volcanoes.

Volcanoes can be caused by mantle plumes. These so-called hotspots, for example at Hawaii, can occur far from plate boundaries. Hotspot volcanoes are also found elsewhere in the solar system, especially on rocky planets and moons.

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