Theory of Plate Tectonics and the Formation of continents.pptx
- 1. Theory of Plate Tectonics and the Formation of Continents
- 2. Plate Tectonics 20th century Many scientists explained the physical attributes of Earth using Raisin Theory, where the earth is likened to a grape that contracted into a raisin due to a cooling process that occurred after the Big Bang about 13.77 billon years ago. Scientist thought that the cooling caused the contraction and the pressure that allowed some parts of the crust to move forward and produced mountains while other parts of the crust buckled downward creating oceans basins and other depressions.
- 3. Clarence Edward Dutton • American seismologist and geologist explained the contracting Earth concept. • ISOSTASY(1889) states that wherever equilibrium exist on Earth’s surface , equal mass must underlie equal surface areas. A great continental mass must be formed of lighter material than that supposed to constitute the ocean floor. 20XX presentation title 3
- 4. Tectonic is a term derived fom Greek word “tekton” means “carpenter” or builder. Tectonic plates have been used by scientist to be describe the movement of lithosphere.It is also called lithospheric plates,they are massive,irregular slab of solid rocks that envelope the surface of Earth.
- 5. 20XX presentation title 5 • It was developed from earlier hypotheses and data collected about the rocks of the ocean floor. • One of the of the rise to this theory is the first World Atlas,Theatrum Orbis terrarium by Abraham Ortelius(January 1,1596) • He noted about similarity between the coastline of Africa, Europe and the Americas and adopted Plato’s story of the demise of Atlantis. • He suggested that America is originally connected to Europe and Africa and that the projecting parts of the two continents would fit the recesses of America. Plate Tectonics Theory
- 6. 20XX presentation title 6 • Proposed the Continental Drift Theory • Origins of Continents and Ocean (1915) • He presented that Pangaea “All Earth” had really existed during Permian period. • He explained that there was a supercontinent name Rodinia. It was predated Pangaea. Alfred Wegener
- 7. Pangaea break into smaller supercontinents: 1. Laurasia-514 mya, drifted southward until it crushed into 2. Gondwanaland Panthalasa – a vast ocean surrounding the Pangaea was formed approximately 356 mya. The to supercontinent were separated by Tethys Sea 251 to 65.5 mya. 20XX presentation title 7
- 8. 20XX presentation title 8 History of Pangaea’s Formation • Now known North America smashed into northwestern Africa during forming a vast mountain range. • Pangaea continued northward and crashed into the ocean floor of Panthalassa it created a chain of mountain ranges extending from Alaska to Southern South America . • At around 200 mya Pangaea began to break apart
- 9. Jurrasic Period • Continental drifting was evidently observed. • The climate was warm and the sea levels were higher than they are now because there were no polor ice during that time. Middle of Jurassic period • Pangaea split into Laurasia and Gondwanaland divided by the ocean. Crustaceous Period • These two and masses broke up into smaller parts which formed the continents that we know today.
- 10. • India was moving northward smashing into Southern Asia. • Movement and plate interactios shapes the worlds tallest mountain, The Himalayas, the Karakoram Range and the Hindu Kush. Mount Everest Karakoram ranges Hindu Kush
- 11. Earth is composed of 58 crustal plates. Out of these plates, scientists have identified 15 major tectonic plates:7 or 8 of which are primary plates and other are smaller plates. Primary • Eurasian plates • Indo-Australian plate • North- American plate • Pacific plate • South American plate • Nasca plate Secondary • Arabian plate • Caribbean plate • Cocos plate Indian plate • Juan de duca plate • Philippine sea plate • Scotia plate
- 12. 44,391,162 km2 30,244,049 km2 24,247,039 km2 17,821,029 km2 14,245,000 km2 10,354,636 km2 7,686,850 km2
- 13. Two basic types of lithosphere plates 1. Continental Lithosphere 2. Oceanic Lithosphere
- 14. Continental crust- solid ground where you step upon.It is lighter tha oceanic crust as it is composed of lower density materials such as granitic rocks. They are formed through volcanic eruption.
- 15. Crust • Basement rock Oldest foundation, 4 billion years old Comprise of a mixture of granite and volcanic rocks. • Platforms Younger layer of continental crust Made of sedimentary rocks • Cratons when basement and platforms connected They often survive the cycle of merging and rifting of continents and are generally found inside the tectonic plates. • Continental margins It is the edge of cratons Composed of sedimentary rocks. When it moves by tectonic plate , natural landform are made such as mountain ranges.
- 16. Oceanic crust- made of heavier basalt and gabbro rocks. 200 million years old. 7km thick It is formed by magma.
Editor's Notes
- #7: Ortelius hypothesis remain silent for several centuries.
- #9: Traces of these mountain ranges can still located on a belt stretching from the southern United States to Northern Europe .
- #11: It is also predicted that some 250-300 million years frim now, the seven continents will move toward each other again reforming the Historical Pangaea.
- #16: When continental margin are moved by tectonic plates natural landforms are made such as mountain ranges.