Volcanoes
Which are the biggest (tallest and largest volume) and smallest volcanoes on Earth? The island of Hawaii is probably the largest volcano on earth. From its base (on the floor of the Pacific Ocean) to the summit of Mauna Kea (about 13 000ft) is some 30 000ft i.e. higher than Everest. The island comprises several coalescing volcanoes including Mauna Loa, Mauna Kea and Kilauea. Mauna Loa alone has an estimated volume of 40 000km**3. It is impossible to say which is the smallest volcano since there are thousands of small eruptions on the ocean floor and around already established volcanoes only a few yards across. Volcanoes are caused when molten rock from within the mantle breaks through the crust and flows out over the surface. But volcanoes don't occur everywhere. There are none in Britain at the moment, although in the past (300-400 million years ago) there were plenty in Wales and Scotland. Volcanoes form in two places on the Earth. The Earth's crust is made up of a series of plates. When these plates collide, one can be forced below the other. As this happens it is pushed into the hotter mantle and starts to melt. The melting rocks rise back up through the mantle and start working the
In subduction zones, where the ocean floor goes down into the mantle some carbonate rocks do get taken down and melted, recycling their carbon dioxide content, but this is a minor source compared with the mantle. A solitary mountain rising from the plain of Campania, it has a base about 48 km (30 mi) in circumference and is surmounted by two summits, of which the higher is the cone known as Vesuvius proper. Lava from Mauna Loa covers about 50 per cent of Hawaii Island, including parts of Kilauea, a crater on the mountain's east flank. It is also light so easy to transport but not very strong so buildings can't be very tall - which is great if you don't want to ruin your skyline with skyscrapers! 4. Carbon is quite a common element deep in the earth, either as the element (graphite, or under very high pressures, diamond) or in carbon dioxide contained in magmas or rocks. This is happening along the middle of the Atlantic Ocean where lavas are erupting out along huge cracks that run from Iceland in the north down to the Falkland Islands in the south. The volcano rises about 5,486 m (18,000 ft) from the ocean floor to the surface and continues up to a height of about 4,205 m (13,796 ft) above sea level, making its overall height from its base on the ocean floor to its summit about 9,754 m (32,000 ft), the greatest such continuous elevation in the world. Because of continuous remodelling and alteration of the fortifications on the rock over the centuries, little remains of the medieval fortifications. Both Mars and Venus have volcanoes much larger than any on Earth, and they have erupted huge amounts of lava onto their surfaces in the past (Olympus Mons on Mars is over 27km high!). Io, one of Jupiter's satellites, about the same size as our own Moon, actually has more erupting volcanoes than the Earth. Fuji is a celebrated dormant volcano of Japan in southern Honshu near Tokyo. This can be thought of like a bunsen burner heating a pan. trips to Vesuvius and Mt Etna in Italy. These gases come from the magma - basically any molten rock beneath the surface - and exactly which gases are released depends on temperature, pressure and what other volatile elements are present.
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Acceptance Essays
