From Theory to Science: The Evolution of Tectonics.
Tectonics is, "the science of the structure of the earth's crust and the movements and forces which shape it.""(Schwarzbach p.76) In general, the earth is divided into three layers-the core, the mantle (lower and upper) and the crust. But, there are two types of crust. The oceanic floors are made of a more dense rock, called basalt and the continents are made of less denser rock, granite. "The oceanic floors, basalt, extends under the continents, though not entirely.""(Flint 8) Then, there's another division, the asthenosphere, which consists of the lower mantle, and the lithosphere, which consists of the upper mantle, the oceanic floors and continental crust. Due to some force' or upward pressure from the asthenosphere, within the lithosphere there are series of cracks, in and between, the oceanic floors and continental crust. From these actions a theory was hypothesized that the continents are in motion.
Throughout the years there have been various theories of the earth's crustal dynamics, which have come to be known as the science of Tectonics or more commonly plate tectonics to try and explain the interaction occurring between the asthenosphere and lithosphere. These theories included, ideas about the developments of the ocean floor, movement of the Earth's magnetic field, and reasoning behind the occurrence of earthquakes and volcanism. Before tectonics, there was the idea of continental drift.
The first to gain considerable notoriety for developing an idea on tectonics was Alfred Wegener, a scientist, specifically in the field of meteorology. Wegener, in 1912, went public with the idea of Continental Drift. Wegener's hypothesis was- the continents consist of lighter rocks that rest on heavier crustal matter and like glaciers floating on water are moving. "Wegener contended that the relative positions of the continents are not fixed but are slowly moving "at a rate of about one yard per century.
