Flashcards
1.2A Tectonics Plate Tectonics
Cards in this deck (15)
- 1Fossil Evidence Didn't Match What fossil of a plant has been found amongst most continents?Fossils of the same green plant have been found on almost all continents, suggesting that they all once had similar climates.
- 2Fossil Evidence Didn't Match Where has the fossil of the tropical plant been found? And what does this suggest?Fossils of tropical plant have been found on Antarctica and on islands in the Arctic Ocean, suggesting that they might have been much warmer in the past.
- 3Timeline of Discovery Glacial Evidence Didn't Match How many years ago did the glaciers cover the southern hemisphere? What was the pattern they made that didn't make sense?About 300 million years ago, glaciers covered the southern hemisphere. The pattern they made as they moved across Earth's surface doesn't make sense unless the continents are arranged as Wegner proposed.
- 4Glacial Evidence Didn't Match What do glaciers not form? How do glaciers move (to and from)?Glaciers do not form in oceans, which would have to have happened in the past, to be consistent with the patterns of movement found in the rocks. Instead glaciers originate on land and move towards the ocean.
- 5The problem with Wegener's Theory What was the main problem?The main problem with Wegener's theory of continental drift was that he could not explain what causes the continents to move
He collected substantial evidence to support his work, since he could no explain the mechanism responsible for the motion of the land masses, the theory was discounted. - 6Convection Currents Who's theory is it? What are they?Holme's theory has been updated to include the more current observations that support his work.
A circular pattern that forms when matter heats and cools, changing the materials density.
The force responsible for moving plate tectonics. - 7Convection Currents What do scientists believe exists under the world oceans? What response did Arthur Holmes come up with to the criticism of Wegener's theory?Now scientists are aware of the crust that exists under the world's oceans, it becomes an assumption that not just the continents move, but the ocean floor does, too. Although this theory is still not credible in the scientific community - gaining support
Arthur Holmes came up with a response to the biggest criticism of Alfred Wegener's theory of continental drift... convection in the mantle. - 8Convection Currents What does the convection current hypothesis say about the Earth's mantle? Because the heat is not distributed what happens? What are the characteristic of the pattern of heat flow?According to the convection current hypothesis, the Earth's mantle is not the exact same temperature throughout. Since the heat is not evenly distributed, the material moves within the mantle. The pattern of heat flow is circular, creating cycles of hot, less dense material rising and cool, more dense material is sinking.
The motion in the mantle move the tectonic plates resting above. The direction of the convection in the mantle determines how the plate interact. - 9Convection Currents Holmes theorised that convection currents move through the mantle the same as... What did he propose that upwards convection might do?Holmes theorised that convection currents move through the mantle the same way heated air circulates through a room, and radically reshape the Earth' surface in the process. He proposed that upwards convection might lift or even rupture the crust, that lateral movement could propel the crust sideways like a conveyor belt, and that where convection turned downwards, the buoyant continents would crumple up and form mountains.
- 10Sea-Floor Spreading What is it? Who discovered it?The age of the rock-forming on the ocean floor supports the Harry Hess discovery that the sea floor is spreading apart. New rock forms along the ridges, then is pushed apart when even newer rock forms.
- 11Magnetic Evidence Explain how the poles reverse.Also supporting the idea of seafloor spreading are clues from the earth's magnetic poles. Think of the earth having a giant magnet in its core. This creates a north and a south poles on earth. We have evidence of this when we use a compass. Scientists theorise that these poles have reversed several times over the lifespan of the earth. This is supported by the discovery of the patterns in iron containing minerals and rocks (iron is magnetic). Magnetic rocks are attracted to the north pole, so pulled towards is, away from south pole.
- 12Magnetic Evidence On average when does our planet reverse? When was the last time? Rocks that contain magnetic material record these pole reversals. Since the ocean floor contains what?Our planet's magnetic field reverses about once every 200,000 years on average. However, the time between reversals is highly variable. The last time Earth's magnetic field flipped was 780,000 years ago, according to the geologic record of Earth's polarity. Rocks that contain magnetic record these pole reversals. Since the ocean floor contains continuously forming new rock, evidence of the pole reversals as well as more evidence that the sea-floor is spreading apart.
- 13Why is the theory of plate tectonics such a significant idea in science?The theory of tectonics tied together the following concepts into a single theory that completely changed the science of geology:
Continental Drift
Sea-floor spreading
Magnetic field reversals
Convection in the mantle - 14GPS Tracks Earth's Surface What was it used for before 1983? Over time technology advanced and what was added to the fleet? To date, measurements on land can be made within what? giving precise information about what?Prior to 1983, the global positioning system GPS, was only used by the military. Over time, technology advanced satellites were added to the fleet that aid in collecting GPS data on Earth, and more applications for the information emerged. To date measurements on land can be made within centre meters, giving precise information to Earth's surface.
- 15Why is the theory of plate tectonics such a significant idea in science?Geologists finally had one theory that could explain all the different evidence they had accumilated to support previous observation, theories and discoveries. Until then these ideas were scattered and some what unrelated. Geologists now use the theory of plate tectonics too...
Show the relationships among geologic events
Explain the occurrence of earthquakes and volcanic eruptions
Explain the formation of mountain ranges and oceans
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- Flashcards on 1.2A Tectonics Plate Tectonics, created by Ethan Molloy on 24/01/2017.
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