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 their way into the crust. Some will get trapped and cool slowly. Others will reach the surface forming volcanoes. There are other places on Earth where the crust is being heated strongly from the mantle below. This can be thought of like a bunsen burner heating a pan. As the Earth's crustal plates move over these "Hot Spots" a series of volcanoes will form.
             This combination of moving the crust over a single hot spot will create a string of volcanoes like those in Hawaii and Indonesia. The line of volcanoes shows the direction the plate has moved in. Once a volcanic cone has built up, it might block itself up if the molten rock solidifies inside it. But when the pressure of more rising molten rocks beneath is great enough, it blows the solidified...

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Volcanoes. (1969, December 31). In MegaEssays.com. Retrieved 13:45, March 28, 2024, from https://www.megaessays.com/viewpaper/44477.html