Earth Movement and Resultant Landforms.ppt

Earth Movement and Resultant Landforms Structure of the Earth Lithosphere : earth’s crust Asthenosphere : upper mantle zone where material is near its melting point acts almost like liquid (appprox. 600 km thick) Earth Movement and Resultant Landforms Recall: You have now seen how the rock-forming processes yield igneous, metamorphic and sedimentary materials of the earth’s crust. Now: We will now look at how huge slabs of the crust itself are moved by heat energy and motions originating within Earth. Earth Movement and Resultant Landforms The Continental Drift Theory Who ? Developed by Alfred Wegener from Germany in 1910s What ? proposed that about 200 million years ago, a super continent called Pangaea (“all Earth”) slowly broke up drifted apart forming 2 landmasses called Laurasia Gondwanaland These 2 landmasses continued to break up drift apart to their present positions Earth Movements and Resultant Landforms Evidences supporting the Continental Drift Theory: coastlines of continents such as South America Africa show that they could fix together like a jig-saw puzzle Rare identical fossils are found in rocks in South America Africa mountain chains of Europe Africa the Americas are geologically related, but separated by the Atlantic Ocean In the 1950s later, geophysical evidence from paleomagnetic ocean floor studies led to the synthesis of ideas in plate tectonics Earth Movements and Resultant Landforms The Theory of Plate Tectonics modifies the old idea of continental drift describes the Earth as a restless planet with plates drifting across the surface is accepted by most earth scientists today as modern, most satisfactory explanation of : Earth Movement and Resultant Landforms 1. internal forces shaping Earth’s surface 2. crustal movements ( folding faulting ) volcanic activity 3. formation of major landforms 4. occurrence of some major natural hazards like earthquakes tsunamis Earth Movements and Resultant Landforms be