Year 3: Drifting continents

The present surface of  the Earth consists of seven continents, five of which are separated by the major oceans. However, about 200 million years ago, all the continents on the Earth were actually one huge “supercontinent” surrounded by one enormous ocean, the Tethys Sea. This gigantic continent, called Pangaea was formed approximately 300 million years ago, and then began to break apart after about 100 million years and spread out to form the continents we know today.

The name is derived from Ancient Greek pan (πᾶν, “all, entire, whole”) and Gaia (Γαῖα, “Mother Earth, land”).
Study the map below.  It’s a map of Pangea mapped with contemporary geopolitical borders. What you see here is an anachronistic mashup — a modern map with its various parts relocated to the general position they would have occupied before Pangea began drifting apart some 100-million years ago.

Political map of Pangaea

Political map of Pangaea

Scientists have found many kinds of evidence that support this idea. The distribution of fossils across the continents is one line of evidence pointing to the existence of Pangaea.

Watch a ‘supervideo’ from Khan Academy:

 

Snider-Pellegrini Wegener fossil map.svgSource: “Snider-Pellegrini Wegener fossil map” by OsvaldocangaspadillaOwn work. Licensed under Public domain via Wikimedia Commons.

Two other types of evidence are:
– Identical rocks have been found on different continents.
These rocks formed millions of years ago, before the continents separated. They formed from the same minerals and under the same conditions.
The shapes of continents fit together like a puzzle. Just look at the east coast of South America and the west coast of Africa—it’s almost a perfect fit!

Pangaea continents.svg
Source: “Pangaea continents” by en:User:KieffFile:Pangaea continents.png. Licensed under CC BY-SA 3.0 via Wikimedia Commons.

 

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s