1265799
Description
Flashcards by Nicola Bywater, updated more than 1 year ago
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Created by Nicola Bywater
over 9 years ago
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| Question | Answer |
| Define plate tectonics theory | Explains global distribution of a geographical phenomena such as seismicity, volcanism, continental drift and mountain building in terms of the formation, destruction, movement and interaction of the Earth's lithospheric plates |
| 1620 | Frances Bacon, countries either side of the Atlantic fit together |
| 1909 | Mohorovicic, seismic waves change speed when travelling through the Earths centre |
| 1912 | Alfred Wenger, - Pangea - Laurasia and Gudwana - 7 major plates - 15 major and 40 minor - Continental drift |
| Name the 8 pieces of evidence for the plate tectonics theory | 1. Continental fit 2. Geological evidence 3. Climatological evidence 4. Paleomagnetism 5. Convection Currents 6. Biological evidence 7. Mid Atlantic Ridge discovery, 1948 8. Sea floor spreading |
| Continental fit | - Seem to fit together - Jigsaw fit - Not perfect due to the difference in erosion, weathering and sea levels - South America and Africa West Coast |
| Geological evidence | - Rocks of the same age, type and formation in South East Brazil and South Africa - Glacial deposits in Antartica, South America and India - Mountain structures in Eastern USA and North West Europe are similar (Appalachian and GlenCo, Scotland) |
| Climatological evidence | - Similar age coal deposits which all must have developed in tropical conditions in Antarctica, UK and North America - These moved apart and drifted away from tropical climates |
| Biological evidence | - Similar fossil formations on either side of the Atlantic - Plant remains from humid swamps forming coal deposits in India and Antarctica - Mesosarus remains in South Africa and Eastern South America (fresh water animal) - Marsupials only in Australia as it drifted away before they were wiped out |
| Mid Atlantic Ridge, 1948 | - Continuous mountain range along the ocean bed - 100km wide and 2.5 km high - Composed of recently formed volcanic rock, with newest rocks nearest ridge - Iceland has rocks under 1 million years - Oldest rocks in USA and Carribean - 5cm per year spreading |
| Paleomagnetism | - Stripes of normal and reverse polarity rocks, a mirrored pattern either side of the ridge - Iron particles in the lava are aligned with the magnetic field of the Earth - The direction of the force changes every 400,000 years - New rocks added equally to either side |
| Convection currents | - The driving force of the movement of plates - Caused as radioactive particles in the mantle decay and give off heat |
| Two adjacent convection currents sink | Destructive |
| Two adjacent convection currents rise | Constructive |
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