Plate tectonics

Questions and awnsers

By: Marco Molldrem

1.What evidence did Alfred Wegener use to support his theory of continental drift?

"Alfred Wegener brought together several lines of evidence to support his theory of continental drift. One is quite simple -- that the continents look like they could "fit" together, much like puzzle pieces that have drifted apart. Then, he noticed that when you put the continental puzzle pieces back together, other things started to fit. For example, the rock layers that form the Appalachian mountains of the eastern U.S. matched quite well with those in Scotland. Fossils found on the east coast of Brazil match quite nicely with fossils found in western South Africa. Also, he noticed that a lot of the fossilized life found in the rock record didn't fit in the climates they were found in. For example, rocks in Alaska contain fossil palm tree leaves, though there have not been palm trees at that latitude for a very long time! Thus, he concluded that the continents must 'drift' around the Earth, occasionally colliding with one another. Though his ideas were not popular at the time, they were the foundation of one of the greatest scientific revolutions in history!"

2. Why do you think people didn't believe the continental drift theory when Wegner first explained it?

I think people didn't believe the continental drift theory when Wegner first explained it because if i were a person back then, I wouldn't believe one crazy scientist who came up with this wierd idea that all the continents were one big continent! I know that sounds a little crazy, but im sure a lot of people thought that, or they probaly thought that all this cant be possible, it's just to hard to believe.

3. Who were the 2 scientists that brought forth supporting evidence to Wegner's theory and what was their eveidence?

The two scientist that brought forth supporting evidence to Wegner's theory were Alexander Du Toit, and Arthur Holmes. Arthur Alexander knew how convection worked and how convection currents worked, and were able to provide more evidence that continental drift existed. They knew how the convection currents were causing continental drift.

4. What are the three types of plate boundaries?

The three types of plate boundaries are convergent boundaries, divergent boundaries, and transform boundaries. A convergent boundary is where two tectonic plates crash or crunch together. At a divergent boundary, plates come apart, think of it as the opposite of a convergent boundary. Last, is a transform boundary, at the transform boundary, two plates slip (slide) past each other.

5. What types of movement can occur between plates and what features can form from this movement?

Some types of movement that can occur, are usually earthquakes and volcanoes. Features that can form are valleys, rifts, mountains, and streams.

6. Where are 3 specific examples of a location on Earth where each type of plate boundary is present?

The San Andreas fault in California, North America, is an example of a transform boundary, Iceland is an example of a divergent boundary, and last Cyprus, an island, is an example of a convergent boundary.

7. What do plate tectonics and ocean trenches have in common

"Ocean trenches are formed from plate tectonics - usually a divergent plate margin (plates moving apart) leaves a gap, where hot magma rises and is cooled in the ocean. This area of land is often lower than the rest, creating a trench along the sea floor".

8. and 9. How old are the rocks off the East Coast of North america in relation to the rocks right along the Mid-Atlantic ridge? Why is this the case?

The rocks off the East Coast of North America are older then in relation to the rocks right along the Mid-Atlantic ridge because when the continents were drifting away from Pangea, new rocks formed to make the Atlantic ridge, but the rocks on the East Coast of North America already existed when Pangea existed because all seven continents used to be together. The only way for the Mid-Atlantic ridge to exist was for the seven continents to drift away.

10. What is a convection current?

"Convection occurs because the density of a fluid is related to its temperature. Hot rocks lower in the mantle are less dense than their cooler counterparts above. The hot rock rises and the cooler rock sinks due to gravity". This is how convection currents work:
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11. What are the 7 major plate boundaries? (Answer is in picture)

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12. and 13. What are two bad events that can happen as a direct result of plate tectonics?

Two bad events that can happen as a direct result of plate tectonics are volcanoes and earthquakes. Volcanoes can occur when two plates colide and one plate sinks beneath the other. Earthquakes can occur when two plates slide past each other.

14. and 15. What are three good things that plate tectonics provide for humans and how do plate tectonics cause these good events?

  1. "Fertile soils-the physical breakdown and chemical weathering of volcanic rocks have formed some of the most fertile soils on Earth".
  2. "Ore deposits-Rising magma does not always reach the surface to erupt; instead it may slowly cool and harden beneath the volcano to form a wide variety of crystalline rocks (generally called plutonic or granitic rocks)".
  3. "Fossil fuels-Heat and pressure at depth transform the decomposed organic material into tiny pockets of gas and liquid petroleum, which then migrate through the pore spaces and larger openings in the surrounding rocks and collect in reservoirs, generally within 5 km of the Earth's surface".