Continental Dirft - Earth Sciences Flashcards
What did geologists in the 1800’s believe about how the continents and oceans came to be?
They believed that as the earth cooled, the crust wrinkled. The high parts of the wrinkles were thought to be the continents, and the low parts were thought to be covered by the oceans. This was called the “Shrinking Theory”.
What did geologists in the 1800s think caused the movements of the continents?
They believed the movement of the continents was just the wrinkles moving relative to each other.
Who proposed the Theory of Continental Drift, and when was it proposed?
Alfred Wegner (a German meteorologist) proposed the theory in 1912.
What did the Theory of Continental Drift suggest?
It suggested that the continents were floating, or drifting, on a denser material below, and that the continents had once been joined in one supercontinent.
What were the four pieces of data Wegner presented to support his theory?
Apparent fit of the continent, fossil correlation, rock and mountain correlation, and paleo climate data.
Explain the apparent fit of the continents.
The continents all appear as though they could fit together, like a jigsaw, especially the continental margins of Eastern Africa and the western coast of South America.
Explain fossil correlation.
Identical fossils of plants and animals (freshwater so they couldn’t swim across the ocean so) can be found on different continents, suggesting that the land was once joined.
Explain rock and mountain correlation.
Rocks and geological structures of the same structures, minerals, and age can be found on different continents, suggesting that the land was once joined.
Explain paleo climate data.
Scratches made by glaciers can be found on rocks in rainforests, proving that they must have been in polar regions at some point. Also, coal, which only forms in warm conditions, has been found in Antarctica, proving that it must have been in a tropical region at some point.
