Continental Drift Theory And Its Evidence PDF

Plate Tectonics: Continental Drift Theory and Its Evidence John Aldrich G. Cortez, RN  The surface of Earth is composed of tectonic plates that are driven by endogenic processes. The continents have been drifting and have not been in exact locations where they are today. Continental Drift The...

Plate Tectonics: Continental Drift Theory and Its Evidence John Aldrich G. Cortez, RN  The surface of Earth is composed of tectonic plates that are driven by endogenic processes. The continents have been drifting and have not been in exact locations where they are today. Continental Drift Theory and Its Evidence The Earth’s crust is divided into plates, known as tectonic plates, and these plates move due to the convection currents in the Earth’s interior. Tectonics - the study of the processes that deform the earth’s crust.  The seven major world Continental continents are North Drift Theory America, South America, and Its Europe, Africa, Asia, Evidence Australia, and Antarctica. Continental Drift Theory and Its Evidence Continental Drift – Alfred Wegener, 1912, Earth has only one giant landmass called Pangaea, which means all land. He hypothesized that this giant landmass slowly broke into smaller land pieces that eventually drifted away from each other which made the seven continents that we now know. Continental Drift Theory and Its Evidence Alfred Wegener introduced the Continental Drift Theory in his book, The Origin of Continents and Oceans. Continental Drift Theory and Its Evidence Some continents, such as South America and Africa fit together. The boundary of each continent is taken at a depth of 1000m on the surface of the Earth. Continental Drift Theory and Its Evidence Similar animal and plant fossils were found in different continents. The fossils of the reptile mesosaurus were found along the coastlines of South America and Africa which are separated by the Atlantic Ocean. Moreover, the fossil of a fernlike plant glossopteris was found distributed in all the continents. Continental Drift Theory and Its Evidence Evidences Supporting the Existence of Pangaea a. The Fit of Continental Shorelines b. Distribution of Glacial Sediments c. Paleoclimate d. Distribution of Fossils e. Distribution of Rocks Continental Drift Theory and Its Evidence a. The Fit of Continental Shorelines Wegener viewed the apparent fit of the continents as pieces of jigsaw puzzle – an indication that the continents were once joined together. Continental Drift Theory b. Distribution of Glacial Sediments Wegener plotted in the map the location of the sediments and rocks that were formed during the last glaciation of the late Paleozoic.  Similar striation on rocks were found in southern parts of South America and Africa, India, Antarctica and Australia. Continental Drift Theory and Its Evidence c. Paleoclimate The apparent shifting of climate belts indicates that the continents have been moving around over time. Continental Drift Theory and Its Evidence d. Distribution of Fossils Wegener mapped the distribution of fossils of known land organisms and he found out that there are fossils of the same organism in certain places in several continents. This can only be explained by the existence of a single landmass that would have allowed organisms to migrate across dry land.  Similar fossils found in different continents suggests that these continents were once joined. Continental Drift Theory and Its Evidence e. Distribution of Rocks Wegener was able to recognize the distinct assembly of rocks occurring on either side of the Atlantic Ocean. Continental Drift Theory and Its Evidence The Appalachian Mountain, Caledonian mountains of Scotland, the Scandes mountains of Norway and the Atlas Mountains of Morocco were once a mountain chain of Pangaea. Continental Drift Theory and Its Evidence Coal seams are found in Antarctica. Coal is produced from organic matter like dead plants and animals. In a very cold place like Antarctica, it would be impossible for most organisms to survive. The presence of coal indicates that the continent was once inhabited by many organisms. It also gives a clue that Antarctica was once located near the equator where abundant animal and plant organisms could be found. Continental Drift Theory and Its Evidence Tillites, which are deposits of rock debris left by glaciers, were found in Africa, South America, India, and Australia. They were of the same age and type. The presence of tillites indicates that those places had glaciers in the past, were once located near the South Pole, and had drifted away from each other. Continental Drift Theory and Its Evidence Pole-fleeing Force – centrifugal force towards the equator which Wegener thought to have moved the continents. Wegener also tried to explain the westward drift of the Americas by invoking the gravitational forces of the sun and the moon, this idea was also quickly rejected. Continental Drift Theory and Its Evidence Sir Arthur Holmes – proposed the presence of convection cells in the Earth’s mantle. When the rocks in the Earth’s interior are heated by radioactivity, they become less dense, and they rise toward the surface of the Earth. When they cool down, they become denser and sink.  The continuous process of rising and sinking of rocks produces convection cells or convection currents. These currents cause the tectonic plates, which include the crust, Continental Drift Theory and to move and drift. Its Evidence  “It's like you know how in a time of crisis, people either come together or fall apart? It feels like we're falling apart.” -Betty Cooper