Wednesday, September 22, 2010

Cross-continental Geological Formations

Since Wagner proposed the theory of continental drift, scientists have been searching for evidence to support his hypothesis. Building on the last piece of evidence discussed, continental shapes, cross-continental geological formations is further proof that once the world may have been joined as once super continent, and has slowly drifted apart to what the land is like today.

Geologists have discovered rock evidence in the form of several mountain belts that end at one coastline, and reappear on another continent. In these situations the age and type of rock match, as well as similar in stru
cture.

A perfect example of this is the Appalachian Mountains that run along the eastern side of North America and end at the coast of Newfoundland. Geologists have found mountains that are similar age and structure to those of the Appalachian Mountains, are found in the British Isles and Scandinavia. When the continents are put
together as Pangea, the mountains form an almost continuous belt.


Monday, September 20, 2010

Continental Shapes

As many have been commenting on for centuries, the shapes of South America and Africa fit together, almost like a jigsaw puzzle. The shapes of the other continents do not fit as seamlessly together at first sight but by mapping the sea floor we are able to see the continental shelf (the true edges of a continent). By using the continental shelf boundaries the puzzle fits with the other continents as well. This evidence suggests that the continents were once all connected and have drifted apart.

As can be seen in the diagram, the continental shelf of the continents fits together snugly.

Sunday, September 19, 2010

Evidence for Continental Drift

Continental drift is the hypothesis that was proposed by Alfred Wegener in 1915, that the continents as they are today broke off from a single supercontinent, Pangea, over 220 million years ago and slowly drifted to their present positions.

There are several pieces of evidence that support Wegener's theory include:
Continental Shapes
Glacial Deposits
Cross-Continental Geological Formations
Age of Ocean Rocks and Sediments
Palaeoclimates
Direct Measurement and Fossil Distribution
These are the pieces of evidence that I will be exploring through this blog.

This is what scientists have figured out Pangea the supercontinent looked like over 220 million years ago.