Tectonic Motion

Prior to the 1960s, most geologists believed in the theory of continental drift.  Moreover, the mountain chains in the ocean were caused by the split in the plates.

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Wegener presented evidence from fossil records, rock formations, and climate data to support his continental drift hypothesis. He hypothesized that earth was once a super  continent and that South America and Africa edges are asymmetrical. 

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There are two main objections to the continental drift hypothesis, first was the lack of a plausible mechanism to explain how continents could move. Another was that continental drift hypothesis was the idea that continents were too massive to be moved by forces within the Earth.

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The lithosphere is rigid and composed of the Earth's crust and the uppermost part of the mantle, while the asthenosphere is partially molten and capable of flow, which is significant in the theory of plate tectonics. Therefore, fault lines and cracks may also be found up to the asthenosphere.

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In the convergent plate boundaries there are collision of tectonic plates thereby leading to subsidence and mountain ranges, on the other hand, at a divergent plate boundary, tectonic plates move away from each other, allowing magma from the mantle to rise and solidify, forming a new oceanic lithosphere.

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Divergent plate boundaries: upwelling, creating new seafloor; Convergent plate boundaries: overriding plates grinding edges of plates only.

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In Iceland, a continental rift was observed, this may be due to continental rifting promotes mantle upwelling and broad up warping of the overlying lithosphere.

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The Red Sea  is a product of oceanic stretching, causing the brittle crust to break into large blocks that sink.

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Two primary driving forces of plate motion are ridge push, where the denser oceanic lithosphere sinks into the mantle, pulling the rest of the plate behind it and slab pull, where the elevated mid-ocean ridges push lithospheric plates apart.

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Researchers use satellite-based methods and ground-based methods such as GPS sonar and submarine to measure relative plate motion.

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