Plate Tectonics

Plate tectonics is a geologic theory which was developed in the 1960s. It is the study of the earth’s crust, with reference to the theory that the lithosphere is divided into rigid blocks, called plates. These plates float on semi molten rock and are thus able to interact with each other at their boundaries which includes convergent, divergent and transform boundaries (Higgleton 2005, 663). These plates combine to create the outer layer of the earth (crust and upper part of the mantle. Both divergent and convergent plate margins are examined in plate tectonics as they are responsible for the formation of various topographical features in the Earth.

Divergent plate boundaries occur when neighbouring continental plates move away from each other resulting in the formation of new lithosphere (Keller 2004, 42). The topographic features which evolve at these areas are primarily because of the extension of plate boundaries which causes rifting in continental and oceanic crust (Strahler 2011, 419). This is because these boundaries are characterised by tensional stresses, and are uplifted by unwilling heat that create fractures, block faulting and fissures. Some features formed are: ocean ridges, the creation of new crust, rift valleys, and volcanoes etc.

Usually some process takes place via sea floor spreading at mid-ocean ridges. Oceanic ridges (at accretive or constructive plate margins) are markers of plate divergence. Both depleted mantle and magma upwell between both plates leading to the formation of new oceanic lithosphere. The movement of the plate is constantly perpendicular to the strike of the boundary, although this is not frequently the case (Menard & Atwater, 1986). These areas are basically, long sinuous ridges that occupy the middle of the Atlantic Ocean and Eastern part of the Pacific. In the Pacific it appears to be an intrinsic characteristic of spreading where a constant direction has been established.

Mid-ocean ridges are created when material...