S.5 A Level Geography Caltec S.5

CONTINENTAL DRIFTING This refers to the large scale movement of land masses of the earth. The earth is made up of continents and ocean basins. It's is believed that continents have not always been fixed in one position but have moved (drifted) though time and are still moving (drifting). Many theories have been put forward by different geographers to explain the origin of ocean basins and continents. These are collectively known as continental drift theories and they include: 1. Expanding earth theory 2. Taylor's theory of continental drifting 3. Wegner's theory of continental drift 4. The sea floor spreading theory 5. The plate tectonic theory. 1. THE EXPANDING EARTH THEORY This theory is one of the earliest theories which suggest that the earth was much smaller and covered with a thin continent and crust at the surface. The earth's interior began to expand and the outer crust was forced to crack. It then separated crustal blocks (continents) and the widened gap in between becomes oceans. The reason why it expanded was that it grew older, it's gravitational force became weaker making its materials spread outward and expanded. 2. THE TAYLOR'S THEORY OF CONTINENTAL DRIFT This was put forward by F. B Taylor in 1910. He described continental drift as huge landslides from the Polar Regions to the equator. According to Taylor, there were originally two land masses called Laurasia near the present day North Pole and the other was the Gondwanaland located near the South Pole. He said that the moon came closer to the earth and exerted a very powerful gravitational force which pulled these land masses from the Polar. Laurasia moved south wards and Gondwanaland moved north wards towards the equator. When the two collided, the sediments in between led to the formation of the Alps and the …