1.0 Subject DefinitionPlate tectonics is a scientific theory that studies how the Earth's plates are driven and shaped by geological forces to keep them in constant motion. The theory explains the Earth's current tectonic behavior, particularly the global distribution of mountain formation, seismic activity, and volcanism in a series of linear belts. (Pitman, WC, 2007) Plate tectonics explains geomagnetic and geothermal phenomena, magma and orogeny, and clarifies the global mid-ocean ridges and rift system, etc. The theory also analyzes geological questions such as the origin of oceanic crust. Plate tectonics has a significant effect on all areas of geology because it helps explain many geological phenomena.Figure1. History of Earth Plate2.0In 1915, scientist Alfred Wegener proposed his theory of "continental drift", which specified that continents were crisscrossing the crust of ocean basins. This helped explain why the outlines of many coastlines, such as those of South America and Africa, looked like a puzzle when they fit together. However, Wegner's theory was controversial because it lacked an explanation of why the continents moved. In 1929, Arthur Holmes developed one of Wegner's hypotheses: the mangle undergoes thermal convection. In the early 1960s, Holmes' idea attracted widespread attention. Harry Hess and R. Deitz developed a similar hypothesis, known as "seafloor spreading." In 1965, JT Wilson proposed a new theory called plate tectonics. In 1967, Xavier Le Pichon published a complete model based on 6 large plates with their relative movements, which refined the theory of “Plate Tectonics”. He also explained the principle of plate movement.3.0 Science Organiz...... middle of paper...... http://www.wadsworthmedia.com/marketing/sample_chapters/0495011487_ch02.pdf [Accessed August 29, 2011]Plate Tectonics, Cotf [online] Available at: http://www.cotf.edu/ete/modules/msese/earthsysflr/plates1.html [Accessed August 29, 2011]Nelson, SA (2003) Global Tectonics, Tulane.edu [online] Available at: http://www.tulane.edu/~sanelson/geol111/pltect.htm [Accessed September 9, 2011] Richer Scales Measures in Earthquakes (2011), Weegy [online ] Available at: http://www.weegy.com/home.aspx?ConversationId=E0B052FE [Accessed September 9, 2011]Earthquake measurement scales (1999), Matter [online] Available at: http:/ /www.matter.org. uk/schools/content/Seismology/richterscale.html [Accessed August 29, 2011]Understanding Plate Motions (1999), USGS [online] Available at: http://pubs.usgs.gov/gip/dynamic/understanding.html [ Accessed August 29, 2011]