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VOLCANOES By: M.Wells Facts About Volcanoes o o o o o Volcanoes are mountains that build higher and higher as they erupt. Once a volcano erupts it might produce ash or lava. Volcanoes can make many types of rocks. There are as many 1,500 active volcanoes around the world. The most important volcano in the United States is Mt. Ranier. Components of a Volcano Parts of a Volcano Images of Volcanic Rocks Scoria Basalt Volcanoes Effects on People Volcanoes affect people in many ways, some are good and some are not. Some of the bad ways are that houses, buildings, roads and fields can get covered with ash. As long as you can get the ash off (especially if it is wet), your house may not collapse, but often people leave because of the ash and are not around to continually clean off their roofs. If the ash fall is really heavy it can make it impossible to breathe. The Good Parts The main good effect that volcanoes have on the environment is to provide nutrients to the surrounding soil. Volcanic ash often contains minerals that are beneficial to plants, and if it is very fine ash it is able to break down quickly and get mixed into the soil. Volcanoes o o Effects On the Environment Volcanoes are notorious for their devastating effects, not only on human life but also on the global environment. Lava, emission of toxic gases, ash fall, lahars and landslides are some of the most dangerous hazards of volcanic eruptions. Lava flows are usually slow and therefore, people can easily escape them. However, they can cause extensive economic loss by burning and burying buildings and crops. o o Volcanic eruptions are generally accompanied by dreadful vibrations in the surrounding areas, which causes landslides. In the past, such landslides were responsible for burying surrounding cities. A volcanic eruption is a natural calamity, that besides wrecking havoc on human life and property, can cause a lot of environmental changes by contributing to acid rain and global warming Volcanoes- Key Terms/Definitions o o o Magma – molten material beneath or within the earth’s crust, from which igneous rock is formed. Lava – the molten, fluid rock that issues from a volcano or volcanic event. Ash – the powdery residue of matter that remains after burning. o Eruption Cloud – a convoluted rolling mass of water vapour and ash that is highly charged with electricity and overhangs a volcano during eruption.