Theory of Continental Drift

Has the earth always looked like this?

What is Pangaea? Pangaea means “all land.” Pangaea was believed to be a supercontinent that existed nearly 240 million years ago. Movement of continents changed through time and Pangaea was no longer a supercontinent.

How do we know Pangaea existed?

Pangaea’s shape has a puzzle like fit. Today’s modern shorelines of continents look as if they were once joined. Most obvious example is between the east coast of South America and the west coast of Africa.

They were once part of the same landmass but were separated by the movement of tectonic plates.

How else do we know pangaea existed? Fossil clues are found on various continents. http://www.sio.ucsd.edu/voyager/earth_puzzle/earth_puzzle_main/fossils/fossils.html

Lystrosaurus Glossopteris Cynognathus, Mesosaurus.

Climate Clues are evident. Glacial deposits and striations (scrape marks) on rock surfaces found in South America, Africa, India, and Australia. So parts of these continents must have been covered with glaciers in the past. Fossils of warm-weather plants found on an island in the arctic, so it must have once been part of a tropical region.

Rock Clues There are similar rock structures found on different continents. For example, parts of the Appalachian Mountains in the eastern U.S. are similar to those found in Greenland and western Europe.

All Clues that support the evidence of Pangaea review: Pangaea’s shape has a puzzle like fit. Fossil clues are found on various continents. Climate Clues Rock Clues

Who Were the Scientists Involved?

Abraham Ortelius Dutch mapmaker Noted the fit between the coastlines of South America and Africa more than 400 years ago. In 1596 suggested that the Americas split from Europe and Africa.

Alfred Wegener German Scientist Suggested that the continents once were connected as one large landmass, which he called Pangaea. In 1912 proposed the Theory of Continental Drift. Initially no one believed him because he did not have the evidence to support his theory.

Theory of Continental Drift This theory states that Pangaea broke up and the pieces or continents slowly drifted to their present day locations. Very controversial when it was first introduced by Wegener because he could not explain why the continents did this and how they did this.