Alfred Wegner was the theorist behind the discovery of tectonic plates back at the start of the 19th century. He found that across the globe there were small bits of evidence that showed the earth was once just one big continent called Pangaea, one part of evidence he found to explain this vast continent was the mountain ranges going through the middle of the West of Africa and the East of South America both of which go right up to the coastline and end in the sea. He noticed that if you connected the two continents up like a jigsaw then the two mountain ranges joined up nicely to make one big one. It isn’t just these two continents that join up but all the continents we have today connected up. For example Canada and the north of Scotland connect agreeably, and they have similar rock formations which indicate that they were laid down at the same time in the same place.
He suggested that at the centre of oceans, molten material would rise from the Earth’s mantle, causing new sea floor to be created, pushing the ocean floor. He also suggested that there were ocean trenches where old sea floor would then go back into the mantle, and molten. He found that these ocean trenches, the deepest parts of the ocean, were very near continental plates. Hess theorized that the action of the sea floor spreading caused continents to move apart and so this being evidence for continental drift, showing why it happened. The evidence of sea floor spreading was further supported by Vine and Drummond, who studied the magnetic pattern of the sea floor.
-”Wegner used the shapes of matching shorelines on different continents as a supporting piece of evidence for continental drift. 3. Describe Earth's magnetic field, including how it has changed through time. -Similar to a simple bar magnet, ends have opposite polarities that cause magnetic objects to align parallel to it’s magnetic field. Poles have wandered from geographical position over the years.
What theory did Alfred Wegener propose? The theory of "continental drift" Explain the "continental drift" theory -the edges of the continents make a rough fit -the Appalachian mountain range breaks off in Newfoundland and reappears across the Atlantic ocean in Ireland, Scotland, and Scandinavia -the similarity of European and American fossils up to 180 million years ago and the dissimilarity of more recent fossils What was Wegener's explanation for the 2 predominant elevations of the Earth's surface? Wegener hypothesized that the difference in heights was due to continents being made up of less dense rock that the rocks of the oceanic basins. What did Wegener's hypothesis about the different elevations mean for his theory? It enabled the idea that the lighter and thicker continental blocks to float over the oceanic crust like icebergs What are the arguments against Wegener's theory?
He claimed that each of the present continents was once joined together as part of a super continent called Pangea. He believed this because he saw that in certain areas continents would fit together for example the west coast of Africa fits together with the east coast of South America, therefore they must have moved apart from one central mass. Other evidence was shown to back up this theory such as the fact that glacier derived clays are found in all of the continents in Gondwana forming one half of Pangea, as one striations in rocks of Carboniferous age. Presently they cover half the globe but would form a reasonably sized polar ice cap if Wegener’s theory was true and the globe was reconstructed in his image of how it used to be. Despite Wegener having no concrete proof as to why this was the case his theory was proved to be accurate, physicists had believed that the earths crust was far from strong enough to be able to force itself apart.
As far back as 1620, Francis Bacon noticed that the west coast of Africa and the east coast of South America looked as if it would fit together. Between then and 1912 others identified further similarities but it was only that year when Alfred Wegner published a theory and subsequent evidence to explain why the earth appeared to be a huge jigsaw puzzle. He suggested that all continents were once a huge supercontinent, called Pangaea- which drifted apart. The evidence for this was the distribution in geology around the globe. Some mountain ranges in Scotland, for example, are similar to those of the east coast if North America.
The main theory of plate tectonics was first developed by a German called Alfred Wegener in 1912. He saw that the continents appeared to fit together like the pieces of a jigsaw, a good example of this is the African and South American coastlines. This would suggest that they were at one time in Earth’s history joined together as part of a super continent Pangaea, which separated forming Gondawanaland and Laurasia to the north of the planed. Later evidence was found to support this theory; fossilised remains of a dinosaur, called the mesosaurus, was found on the east coast of South America and the west coast of Africa around the country of Gabon. There were also the same fossilised pollen species and rock sediments on these coastlines.
Plate tectonics was first suggested as a theory by the geologist Alfred Wegener in 1915 when he proposed the concept of continental drift. Back in the geological past, what is now South America, Africa, Australasia and Antarctica fitted together into a supercontinent known as Gondwanaland; with North America, Europe and Asia fitting into another supercontinent known as Laurasia. (OCR AS/A2 Geology, Mugglestone et al, 2008). These were once believed to be joined to form one major central global landmass known as Pangaea (Introducing Geology, Graham Park). But now due to the global distribution of these major plates it has been proposed by Wegener and his successors that convection currents in the mantle are the cause of the movement of plates.
Plate Tectonics is the theory that explains the structure and motion of the Earth’s lithosphere. The theory states that the Earth’s crust is split into large sections called tectonic plates, and these move relative to one another creating boundaries at which plates converge, diverge and move past each other. As far back as 1620, Francis Bacon noticed that the west coast of Africa and the east coast of South America looked as if it would fit together. Between then and 1912 others identified further similarities but it was only that year when Alfred Wegener published a theory and subsequent evidence to explain why the earth appeared to be a huge jigsaw puzzle. He suggested that all continents were once a huge supercontinent, called Pangaea- which drifted apart.
Assess the strength of relationship between tectonic processes and major landforms at the Earth’s surface. There is a range of evidence to suggest there is a strong relationship between tectonic processes and major landforms at the Earth’s surface due to, for example, the presence of volcanoes, fold mountains, trenches, and ridges. Tectonic processes include, divergence, which is when plates move away from each other, convergence, when plates move toward each other and collide, Subduction zones, which occur where an oceanic plate meets a continental plate and is pushed underneath, Obduction, which occurs when the continental plate is pushed under the oceanic plate, and collision boundaries, which occur where two continental plates collide and push upwards to form large mountain ranges. However this evidence is weakened by the process of weathering and erosion, due to the presence of the Grand Canyon, one of the Earth’s major landforms. As well as landforms caused by river processes, such as the Bangladesh Delta – which can be seen via satellite - therefore a major landform.