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28 Cards in this Set
- Front
- Back
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What elements are the core made of? |
Iron and nickel |
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What temperature can the inner core reach? |
Over 4,000 degrees Celsius |
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What is the mantle mostly made up of? |
Silicate rocks |
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What is the part of the mantle further away from the core called? What is its consistency? |
Asthenosphere Semi-molten |
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What is the lithosphere? |
The rigid top part of the mantle and the crust |
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How thick is continental crust? Is it dense? |
30 - 70 km
Less dense |
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How thick is oceanic crust? Is it dense? |
6 - 10 km thick More dense |
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What are the circular movements of semi-molten rock called? |
Convection currents |
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What provides the heat for convection currents? |
Radioactive decay in the mantle and core |
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When did plate tectonic theory begin to develop and how? |
17th century People first noticed that the coastlines of South America and Africa looked like they could fit together like a jigsaw |
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When did Alfred Wegener propose the theory of continental drift?
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1912 |
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What did Wegener suggest in his theory? |
All the continents were once joined as a super continent- Panagea |
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What happened with plate tectonic theory in the 1950s? |
Paleomagnetism provided evidence and supported continental drift |
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What happened with plate tectonic theory in the 1960s? |
Process of sea floor spreading discovered, providing the mechanism for continental drift |
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Name the five pieces of evidence for plate tectonic theory. |
1) Geology 2) Fossil records 3) Living species 4) Climatology 5) Paleomagnetism |
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GEOLOGY
Which two coastlines looked like they may have once fitted together? |
South America and Africa |
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GEOLOGY What else can also be matched? Give an example. |
Age, rock type, distribution etc of mountain ranges e.g. mountains in Scotland, Norway and Sweden are similar to those on the East coast of North America |
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FOSSIL RECORDS Give two examples of fossil records that can be matched by land mass. |
Lystosaurus Mesosaurus |
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FOSSIL RECORDS Outline how fossil records provide evidence for plate tectonic theory. |
It is very unlikely these species migrated across thousands of miles of water or evolved in different places Fossil records suggest that these land masses were joined billions of years ago when these species were alive |
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LIVING SPECIES Give an example of a living species that provides evidence for plate tectonic theory. |
Earthworms of the family Megascolecidae are found in New Zealand, parts of Asia and North America Suggests the continents were once joined, allowing the earthworms to travel between them |
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CLIMATOLOGY Outline how large coal deposits provide evidence for plate tectonic theory. |
Large coal deposits formed in tropical conditions have been found in North America and parts of Europe Suggests these regions were closer to the equator and drifted over time |
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CLIMATOLOGY Outline how glacial deposits provide evidence for plate tectonic theory. |
Similar glacial deposits are found in Antarctica, Africa, South America, India and Australia The distributions of these glacial deposits can be fitted together, suggesting they were once located close to the South Pole but drifted apart |
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PALEOMAGNETISM What is paleomagnetism? |
The study of the history of the Earth's magnetic field |
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PALEOMAGNETISM How often does the Earth's magnetic field reverse polarity? |
Every 200,000 years or so |
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PALEOMAGNETISM What happens in the magma to indicate polarity? |
When magma erupts, magnetic minerals in the molten rock align themselves with the direction of the Earth's magnetic field, which is fixed when the rock solidifies |
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PALEOMAGNETISM What is normal polarity? |
Magnetic North towards the North Pole |
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PALEOMAGNETISM What is reverse polarity? |
Magnetic North near the South Pole |
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PALEOMAGNETISM How does paleomagnetism provide evidence for plate tectonic theory? |
Creates a series of alternating stripes Older ones are further from the mid-ocean ridge Shows the plates are moving apart |
