More than 240 million years ago, a supercontinent existed on the earth.  This supercontinent, known as Pangaea (pronounced Pan-jee-a; also spelled Pangea), was formed when many smaller continents converged (joined together) throughout the Paleozoic Era.  The Paleozoic Era lasted from about 550 to 245 million years ago.

 

More than 240 million years ago, a supercontinent existed on the earth.  This supercontinent, known as Pangaea (pronounced Pan-jee-a; also spelled Pangea), was formed when many smaller continents converged (joined together) throughout the Paleozoic Era.  The Paleozoic Era lasted from about 550 to 245 million years ago.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Figure 1. What Pangaea looked like 240 million years ago.  Modern continents are numbered:  1) N. America; 2) Eurasia; 3) S. America; 4) Africa; 5) India; 6) Antarctica; and 7) Australia. 

 

When Pangaea was formed, a big ocean was created that covered the rest of the earth.  This ocean is known as Panthalassa.  Pangaea began to break apart approximately 240 million years ago, splitting into the seven continents found today.  As Pangaea began to rift, or split apart, Panthalassa shrank.  As the newly formed continents were formed and moved apart, the Atlantic Ocean was created.  The oldest sediments and seafloor crust found in the Atlantic are approximately 180 million years old.

 

In the early 1900’s Alfred Wegener, a German scientist, found evidence that Pangaea existed. There are several compelling pieces of evidence:

• Shape – the shape of many continents look as though they were once joined. The most obvious "fit" is between the east coast of South America and the west coast of Africa.

 

• Fossil Evidence - fossils of a fresh water swimming reptile, Mesosaurus have been found on the east coast of southern Brazil and the west coast of Africa.  This reptile could not possibly have swum the 3,000-mile distance across Atlantic Ocean.  Many other examples of fossils currently found on two continents that are separated by vast oceans exist.

 

 

 

 

 

 

 

 

 

 

 

Figure 2.  Freshwater reptile Mesosaurus.

 

• The freshwater reptile Mesosaurus were found in what two landmasses? How does that evidence support the existence of Pangaea?

 

• Glacial Deposits - Glacial deposits have been found in southernmost regions of South America, Africa and Australia.  Glacial striations, "scrape" marks on rocks caused by moving glaciers, have been found on rocks in these areas and are similar to striations found in Antarctica, showing that glaciers moved across the regions when the continents were attached as part of Pangaea.

 

 

 

Even with the tremendous amount of evidence supporting Pangaea’s existence, the questions remained:  How and why did the modern continents form and move to their present locations? Wegener proposed the Continental Drift Hypothesis, which stated that Pangaea broke apart and the continents “drifted” to their modern locations.