VolcanoesVolcanoes are natural phenomena that occur on the Earth's surface through which molten rocks and gases escape from below the surface (Tarbuck, 139). These volcanoes are very interesting to observe and study because of their amazing occurrences and majestic lava eruptions. Volcanoes have been studied since the beginning of humanity and the word "volcano" is thought to derive from Vulcano, a volcanic island in the Aeolian Islands of Italy whose name in turn comes from Vulcan, the name of a god fire in Roman. mythology. Made up of several types, volcanoes can extrude several forms of magma and can also release several gases. These extruded materials can affect the structure and atmosphere of the Earth. There are three types of volcanoes on Earth. The most common type of volcano is the cinder cone. An ash volcano is built from ejected fragments of lava that take on the appearance of ash when they begin to harden in flight. (Tarbuck, 152) The structure of this volcano is determined by the shape and slope that the pyroclastic material forms as it hardens. Usually these volcanoes are symmetrical in shape, with elongated flanks and may have large craters caused by volcanic activity (Tarbuck, 153). Examples of cinder cone volcanoes are Holocene in Utah and Capulin in New Mexico. In addition to the cinder cone volcano, the shield volcano is also another common type of volcano on Earth. The shield volcano is produced by the accumulation of fluid basalt lava and has the shape of a large, slightly domed structure (Pillai). Younger shields tend to emit fluid lava from a central vent and have sides that vary from 1 to 5 degrees (Pillai). On the other hand, an older shield volcano...... middle of paper ......cause_and_effect_of_volcanoes_pg2.html?cat=58>.Pillai, Maya. “Volcanic Eruptions: What Causes Volcanoes to Erupt.” Buzzle Web Portal: intelligent life on the Web. Internet. May 29, 2010. Sigurdsson, Haraldur. Encyclopedia of volcanoes. San Diego: Academic, 2000. Print. Tarbuck, Edward J., Frederick K. Lutgens, and Dennis Tasa. “Volcanoes and other igneous activities.” Earth Introduction to physical geology. 8th ed. Upper Saddle River, NJ: Pearson/Prentice Hall, 2005. 138-71. Print. “Volcanic gases and their effects.” USGS.com. U.S. Department of the Interior, April 30, 2010. Web. May 29, 2010. Williams, Howel, Alexander R. Macbirney, and Christine Macbirney. Volcanology. San Francisco, California: Freeman, Cooper &, 1979. Print.