Tectonic Plates
Pieces of lithosphere that move around on top of the asthenosphere are called tectonic plates. Tectonic plates move in different directions and different speeds. All tectonic plates have names and each tectonic plate fits together like a jigsaw puzzle. There are ten major tectonic plates. The pacific plate covers most of the pacific ocean and is the largest tectonic plate. The North American plate covers North America and part of the Atlantic ocean. The Cocos plate is the smallest tectonic plate and runs from the coast of Mexico to the Northern tip of South America. The Nazca plate covers only oceanic crust and runs from the Western tip of South America to the Eastern part of the Pacific ocean. The South American plate covers covers the landmass of South America and the Atlantic coast to the Eastern side of the country. The African plate covers the continent of Africa and the Atlantic ocean bordering the continent.The Eurasian plate covers all of Europe, Russia, and most of Asia. The Indian plate covers the country of India and the Indian ocean to the South. The Australian ocean covers Australia and the water surrounding it. The Antarctic plate cover Antartica and the Southern waters surrounding it. The hypothesis that all the continents were joined together is called Pangaea. Continental drift is the hypothesis that states that the continent once formed a single landmass, broke up, and drifted to their present locations is called Pangaea. There are three types of boundaries. Convergent when they collide, divergent when they separate, and transform boundary when they slide past one another. Compression and tension are the two types of stress. Compression occurs when two tectonic plates collide. Tension occurs when forces stretch a tectonic plate area. Folding is the bending of rocks because of stress in the earths crust. The surface along which rocks break and slide is called a fault. The blocks of crust on each side of the fault are called fault blocks. The three types of faults are normal faults, strike-slip faults, and reverse faults. A normal fault moves, this causes the hanging wall to move relavent to the footwall. A reverse fault moves and causes the footwall to move up to the hanging wall. A strike-slip fault form when opposing forces cause rock to break and move horizontally. ( Holt Science and Technology Earth Science) ( http://www.freewebs.com/morganisrupert/photos.htm) (http://teacher.scholastic.com/scholasticnews/magazines/assets/sn_ts_031411_tectonic.html )