The landscape is, therefore, irregular, comprising both hills and valleys; hence, resulting in short rivers.
On the other hand, in passive continental margins, there is limited tectonic activity; the major processes that occur here are weathering and erosion. This results in level, flat landscapes along the beaches, characterized by long rivers and large debris of sediment.
The oceanic ridge, which is a continuous submarine mountain range spanning 80000 kilometers, is elevated relative to the other areas of the ocean floor. The elevation is brought about by convection currents that rise from deep within the earth’s crust through a mantle in a line of weakness, in the form of magma. When it emerges on the earth’s crest, lava cools down and forms a new surface on the sea bed. Continuous eruption and cooling of lava leads to a build-up of materials, which in turn cause elevation at the point the activities take place. The result is a ridge, which is higher than other sections of the ocean floor.
Mesosaurus was a reptile that lived in fresh water lakes thousands of years before the existence of dinosaurs. The fact that scientists found its remains, in Eastern South America and Western Africa only, suggests that the two continents could have existed as one land mass millions of years ago. Whereas some schools of thought could have it that the reptiles could have swum across the Atlantic Ocean, this could not happen since Mesosaurus could neither survive in the ocean waters because of their saltiness, nor swim across the ocean due to its expansive nature. These, together with the fact that the coastlines of the two continents fit like pieces of a jigsaw puzzle, enforces the theory that the two continents once existed as one expansive land mass.
One of the main objections to Wegener’s Continental Drift Theory was his inability to explain the mechanism through which the continents drifted apart. He proposed two theories; a