1.3 Continental Drift and Plate Tectonics

1.3.1 Continental drift theory

German scientist Alfred Wegener, in 1915, proposed the hypothesis that the continents had once formed a single landmass before breaking apart and drifting to their present locations. His observations were based on the similarity of coastlines and geology between south America, Africa and Indian peninsula, Australia and Antarctica, Figure 1.2. He proposed that a large continent termed Pangae existed in earth around 200 million years ago and was surrounded by an ocean called Panthalassa. It was postulated that this super continent broke into several pieces that formed the present continents. These pieces have subsequently drifted into their current position. Although, he presented much evidence for continental drift, he was unable to provide a convincing explanation for the physical processes which might have caused this drift. He suggested that the continents had been pulled apart by the centrifugal pseudo force of the Earth's rotation or by a small component of astronomical precession. But the calculations showed that these forces were not sufficient cause continental drift.