Cross-continental geological formations

Since the discovery of continental shapes, scientists have been searching for further evidence to explain whether it is just a coincidence or whether it can be used to explain continental drift. Offering further support for continental shapes is cross-continental geological formations. This piece of evidence builds on the theory that the continents were once joined together.

Geologists have discovered that positions of some geological formations align perfectly when the continents are placed together. One of the most obvious geological structures is mountain chains. This is because mountain chains have been found at one end of a coastline, only to reappear on a landmass across the ocean.  An example of this as shown in the picture, illustrates how the Appalachian Mountain chain runs through the eastern United States, ending off the coast of Newfoundland.

The next picture demonstrates that if the continents were placed together, these mountain chains would continue unbroken and form a nearly continuous chain.

However, the problem with the accuracy of matching geological formations is establishing which rock formations and geological features are significant in trying to find a match between the continents. This is because geological features were formed before the continents were joined, during and after the splitting of the continents. To help solve this, geologists try to find a match by finding the age of ocean rocks and sediments, which will be mentioned in a later blog.

Continental Shapes

The origin of the theory that continental drift has occurred, is from Alfred Wegener’s fascination that the continents seemed to fit perfectly together like a jigsaw puzzle, despite being thousands of kilometres away from each other.

Alfred Wegener creatively explains this by stating, ‘It is just as if we were to refit the torn pieces of a newspaper by matching edges and then checking whether the lines of print run smoothly.’

Alfred Wegener used present-day shorelines to show how the continents fit together. However, he was challenged when others correctly argued that erosion continually changes shorelines over time. Today, scientific studies using computer-generated models of the continents show that they fit extremely well, patriculary if the continental shelf margins are used instead of the shoreline. This is because it displays the entire continental shape rather than just the landmass seen from space. This evidence suggests that they were once connected together as a supercontinent called ‘Pangea’ and throughout time have drifted apart.

The most common example used to explain this idea, is how the east coast of South America fits perfectly with the west coast of Africa.

The biggest problem with this evidence is understanding what forces were strong enough to cause the continents to move. However, other evidence discovered later will help support the arguement.

Therefore the question is, is this fit an accident, or does it truly support the hypothesis that the continents were once joined together?  

 

Continental Drift

The map of the world today, is very different to what the world looked like 200 million years ago. For a long time many people believed that the continents have always been in the same place. It was not until 1915, when Alfred Wegener proposed the theory of continental drift, did his investigation open a gateway to bigger possibilities. The theory of continental drift suggested that the continents had once been joined together, split apart due to plate tectonic movement and moved slowly around the surface of the Earth.

The idea of continental drift challenged many scientists. However, as scientists add to the theory or discover new evidence, they became closer to explaining continental drift.

Evidence supporting continental drift:

- Continental shapes

- Cross-continental geological formations

- Fossil distribution

- Age of ocean rocks and sediments

- Direct measurement
- Glacial Deposits
- Palaeoclimates