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Roger Weller, geology instructor
wellerr@cochise.edu


Pangea
Jason Cross
Physical Geology
Spring 2006
                                                            Pangea


           What is the theory of Pangea? The theory of Pangea is that millions of years ago all the continents were joined together in one enormous land mass known as Pangea. Then for a reason that is still not known for sure, the continents broke apart and began to drift in opposite directions. The theory goes on to say that the continents will continue to drift until they meet again, in a different configuration.
 

            What causes plate tectonics? The earths lithosphere, or the top layer consists of large plates that move around in response to the flow of the asthenosphere beneath it. The asthenosphere consists of molten magma that is constantly flowing from its edges to its center where it moves upward to spread outwards, causing the plates to move.
 

            Where was Pangea locate on the surface of the planet and what did it look like. Pangea is believed to have been situated around where current day Antarctica is now. Pangea started to break up into smaller supercontinents, called Laurasia and Gondwanaland, during the Jurassic Period. By the end of the Cretaceous period, the continents were separating into land masses that look like our modern-day continents. An Austrian geologist stated that there had been once a land bridge connecting South America, Africa, India, Australia, and Antarctica. He named this land mass Gondwanaland. For how Pangea looked, it is better shown through a picture, than through words.
 

 

             So, what is happening now with the continents. As we speak, the continents are moving, they are always moving, how they move so slowly that you cant tell. Some of the continents move merely 1.5 inches a year, while the others move with lightning speed of 2.5 inches per year. It's about as fast as your fingernails grow. Maybe a little bit slower, (Scotese)". Still, over millions of years that minute movement will drive the continents together.
 

             The big question becomes, what will happen, what will be the effect of these incredibly large masses running into each other. What few people know is that it's already began. Africa has been slowly colliding with Europe for millions of years (Scotese).  "Italy, Greece and almost everything in the Mediterranean is part of (the African plate), and it has been colliding with Europe for the last 40 million years." The Alps and the Pyrenees mountains have been pushed up, and has been causing earthquakes that occasionally strike Greek and Turkey. "The Mediterranean is the remnant of a much larger ocean that has closed over the last 100 million years, and it will continue to close," he said. "More and more of the plate is going to get crumpled and get pushed higher and higher up, like the Himalayas." Australia is also likely to merge with the Eurasian continent.
 

             Australia is moving north, colliding with Southeast Asia. Soon, the left shoulder of Australia will get caught, and then Australia will rotate and collide against Borneo and south China, adding to Asia. Meanwhile, America will move further away from Africa and Europe as the Atlantic grows. In the case of the widening Atlantic, geologists think that a "subduction zone" will eventually form on either the east or west edges of the ocean. At a subduction zone, the ocean floor dives under the edge of a continent and down into the interior of the Earth. "The subduction zone turns out to be the most important part of the system if you want to understand what causes the plates to move( Scotese)."
 

             If a subduction zone starts on one side of the Atlantic -- Scotese thinks it will be the west side -- it will start to slowly drag the sea floor into the mantle. If this happens, the ridge where the Atlantic sea floor spreads would eventually be pulled into the Earth. The widening would stop, and the Atlantic would begin to shrink. Tens of millions of years later, the Americas would come smashing into the merged Euro-African continent, pushing up a new ridge of Himalayan-like mountains along the boundary. At that point, most of the world's landmass would be joined into a super-continent called "Pangea Ultima." The collision might also trap an inland ocean (Scotese).
 

             What will Pangea Ultima look like you may wonder?
 



References

http://www.enchantedlearning.com/subjects/dinosaurs/glossary/contdrift.shtml

http://www.ucmp/berkeley.edu/geology/tectonics.html

http://antwrp.gsfc.nasa.gov/apod/ap001002.html

http://www.firstscience.com/site/articles/continents.asp

http://www.geography-site.co/uk/pages/virtual-school/lessons/tectonics02.html

http://college.hmco.com/geology/resources/geologylink/glossary/p.html

http://www.ig.utexas.edu/research/projects/plates/images/pangea.jpg