What evidence did Alfred Wagner use to support his theory ofcontinental drift? • Alfred Wegeners fully developed theory of continental drift attempted to point out evidences that the continents were once joined into a single continent he called Pangea. Ever since the continents were all mapped, people had noticed that many coastlines, like those of South America and Africa, looked as though they would fit together if they could be moved like puzzle piece. He noticed that, based on nineteenth-century longitude determinations, it appeared that Greenland had moved a mile away from Europe in a hundred years. And Paris and Washington, D.C., seemed to be moving apart by about 15 feet each year while San Diego and Shanghai got about six feet closer.
Why do you think people didnt believe continental drift theorywhen Wagner first explained it?• Wegener could not come up with an acceptable way to explain how the continents moved and this caused speculation among the people.
Who were the two scientist that brought forth supporting evidenceto Wagners theroy, and what was their evidence? • Arthur Holmes and Harry Hess helped Wagners theroy because Holmes suggested that the continents didnt move but were "carried" by larger pieces of the earths crust. The controversy quieted down and fell from prominence until the 1960s, when new evidence was brought to the fore. Discoveries of the Mid- Oceanic Ridge and the work of Harry Hess and others led to the development of plate tectonics. Though not without problems, this theory has gained wide acceptance.
What are the three different types of plate boundaries, describe eachtype? • Divergent boundaries -- where new crust is generated as the plates pull away from each other. • Convergent boundaries -- where crust is destroyed as one plate dives under another. • Transform boundaries -- where crust is neither produced nor destroyed as the plates slide horizontally past each other.
Give an example on Earth where each type of plate boundary ispresent. Convergent Divergent Transform
What are the three different types of convergent plate boundaries? • Oceanic-continental convergence • Oceanic-oceanic convergence • Continental-continental convergence
What types of tectonic forces create mountains? • The type of tectonic forces that create mountains are called converging plates. As two continental plates push together, the stress forces them both upwards. Because of this the Himalayas are still growing.
• Graben are produced from parallel normal faults, where the hanging wall is downthrown and the footwall is upthrown. The faults typically dip toward the center of the graben from both sides. Horsts are parallel blocks that remain between grabens, the bounding faults of a horst typically dip away from the center line of the horst.
What are two bad things that can happen as a result of platetectonics, how did plate tectonics cause these events? • Volcano eruptions and earthquakes. When plates bump into each other, a source of energy is created deep inside the earth called a focus.
What are three good things that plate tectonics provide for humans,how do plate tectonics provide these things? • fertile soils, ore deposits, and fossil fuels