Unit 1. 2. 2 continental drift
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Earthquakes occur when energy is rapidly released due to movement along faults in the Earth's crust. Fossils found across different continents provide evidence that the continents were once joined together in a supercontinent called Pangaea, which has since broken apart due to continental drift. The theory of continental drift was initially proposed in the early 20th century but was rejected due to the lack of a proposed driving mechanism until the development of the theory of plate tectonics.
Unit 1. 2. 2 continental drift
- 3. Earthquake is a vibration of the Earth produced by the rapid release of energy because of the slippage along a fault in the Earths crusts.
- 5. S wave is a pulse energy that travels faster through the Earth and through liquids.
- 7. The crust is the thinnest and outermost layer of the Earth that extends from the surface to about 32 km below.
- 9. The outer core is mainly made up of iron and nickel moving around the solid inner core , creating Earths magnetism.
- 13. Pangaea
- 14. What element is the most abundant in the Earths crust?
- 15. Oxygen
- 16. What elements make up most of the
- 18. What materials make up the inner core?
- 19. Iron and Nickel
- 20. Is the inner core solid, liquid or gas?
- 27. Analysis: What do the Glossopteris fossils tell us about the early positions of the continents? Regions were once connected.
- 28. If Glossopteris fossils were found in Antarctica, what does this indicate about the climate of this continental before? It proves that Antarctica had a tropical climate before.
- 29. If the climate and the position of a place are relative to each other, where then was the initial location of Antarctica 250 million years ago? It tell us that Antarctica was nearer to the equator before as compared to where it is
- 30. What does the presence of Mesosaurus fossils tell about the initial location and position of South America, Africa and Antarctica? It tells that these continents are connected before, since this kind animal cannot swim across the vast ocean.
- 31. What clues are useful in constructing Pangaea? The edges of the continents are useful in constructing the Pangaea. The presence of evidences found in the same continents made the reconstruction easier.
- 32. Which continents do you think were neighbors before? Europe and Asia in the North North America, South America and Africa in the middle. Australia and Antarctica together with India in the South
- 33. Will there be possibility that the current location of a continent would be different 100 years from now? Yes, if the continents continue to move.
- 34. Where do you think was the Philippines located during the time that the Pangaea existed? Philippines could not existed during the time of Pangaea but borne out of volcanic eruptions and other tectonic
- 36. Movement of the Earths continents relative to each other.
- 37. Abraham Ortelius (1596) first put forward the hypothesis that continents drift In his work Thesaurus Geographicus suggested that the Americas were torn away from Europe and Africa by earthquakes and floods
- 38. Alfred Wegener (1596) Continents had once formed a single landmass before breaking apart and drifting to their present locations First use the phrase continental drift
- 40. Evidence that continents drift Similar plant and animal fossils are found around different continents shores, suggesting that they were once joined.
- 41. Examples: Fossils of Mesosaurus, a fresh water reptile rather like a small crocodile, found both in Brazil and South Africa Fossils of the land reptile Lystrosaurus from rocks of the same age from South America, Africa and Antartica
- 42. fossils of the Glossopteris, an ancient fern, are found in South America, Africa, Antarctica, India, and Australia. It was hypothesized that such a distribution could only come about if the continents were all part of the one super-continent.
- 44. The complementary arrangement of the facing sides of South America and Africa is obvious, but is a temporary coincidence.
- 46. Wegener noted that the rock sequences in South America, Africa, India, and Australia are very similar. Wegener showed that the same three bottoms layers occurred on each of the continents.
- 47. The bottom layer, called tillite, was thought to be of glacial origin. The middle layer composed of coal beds, shale and sandstone contained Glossopteris fossils, as did the bottom tillite layer. The top most and youngest layer is lava flows. Such a strong similarity in the rock record of these localities, now separated by great geographic distance, lent credence to Wegener's notion of continental drift.
- 48. The occurrence of glacial features in the geologic record of South America, Africa, India ,and Australia provides further evidence for the notion of continental drift. Glaciers affected all or part of these continents at the same time in Earth history.
- 50. Rejection of Wegeners theory One problem was that the a plausible driving force was missing. As late as 1953, Carey introduced the theory of plate tectonics thus the theory of continental drift was rejected by the physicist Scheiddiger