Year 8 Geography
The Formation of Earth and Pangaea
Earth formed about 4.6 billion years ago with the big bang which also created the sun and other planets and basically our whole solar system. Quite a few million years later a large island called Pangaea formed in the middle of Earth ( this happened approximately 220-240 million years ago ). The image below is a rough picture of how Pangaea would have looked like. Although with the continental border lines you can just about work out which continent goes where but without its almost impossible to identify the different continents. Although the huge super continent looks like just one big blob of Earth but actually its made up of two semi-super continents with a Northern part ( Laurasia ) and a Southern part ( Gondwanaland ). The last time Pangaea was one super continent was in the early-middle jurassic.
As soon as Pangaea formed it was beginning to split up. First into Laurasia ( Northern part ) and Gondwanaland ( Southern part ). This created Tectonic plates which then mostly also made up separate continents. These continents very slowly drifted apart and if you look at a map or a globe at a big scale you can actually see that in proportion to the Earths surface they haven't actually moved that far. At first, many Scientist found it hard to prove this idea for a few reasons like that it goes against religious teachings. For me there were two clear points that convinced me. One was that fossils were found in Antarctica. This meant that Antarctica once was in a condition that would support trees growth which could only mean that Antarctica was up further North. The second idea was that you can quite clearly see that some of the continents can easily fit together e.g. South America's eastern coastline and Africa's western coastline.
Tectonic Plates and Earth's future
Tectonic plates are big slabs of Earth which come in two variations: Oceanic plates which are newer, denser and Heavier; Continental plates which are older, less dense and lighter. But these huge plates don't just sit around all day they are actually moving about and that is because of what is going on under Earth's surface. Boiling hot magma from deep inside the mantle rises towards the crust. But the magma has nowhere to go so it splits; half of it goes to one side along the crust, the other goes to the other side of the crust. As the magma cools and looses energy it drops back down towards the outer core as you can see below in the diagram. The magma goes around in a never ending cycle. This motion of the magma going along one side of the crust is the motion that moves the different tectonic plates. Of course if the tectonic plates never stop moving I think that most of the plates will continue to separate and slowly move around the Earth. They'll probably move into the Pacific ocean because there is a lot of space there and I think they might make another super continent and then brake of again in a big cycle
By Jacek Schmidt 8c