Oceanography essay

While marine geology has been primarily focused on marine sedimentation, since 1960, its scope has broadened to include new concepts such as seafloor spreading, continental drift and plate tectonic theory. The earth’s lithosphere is divided into three major layers; namely the crust, the mantle and the core, each characterized by a unique composition. Plate tectonics theory posits that the crust is divided into eight mobile plates and several smaller ones which can fit together in the manner in which jig saw puzzle pieces are assembled (Jackson 36). The eight mobile plates are; The Nazca plate, the African plate, the South American plate, the North American plate, the Indo-Australian plate, Eurasian plate and the Antarctic plate. The plates’ motion is slow but constant, estimated to be about 100 mm per year.

The first was the fit of the continents where he observed that the opposing coastlines on the opposite sides of the Atlantic Ocean fit into each other and an even better match is found when continental shelf edges are used. Secondly, he pointed out the matching mountain belts and rocks. A match up of mountains is found when Pangaea is reassembled for example the mountains of North America and Western Europe (Coulomb 62). Thirdly, he noted that there exists definite linked patterns in the distribution of fossils on re assembly of Pangaea. For example the reptile Mesosaurus fossils have been discovered in South America and southern Africa confirming that the two were in deed side by side. Scientist Robert Dietz proposed in the 1960s that beginning from the ridges, ocean floors spread and drift towards the trenches (Wilson and Dietz 542).