P4+-+Plate+Tectonics

=**Plate Tectonics** = A theory of global tectonics in which the lithosphere is divided into a number of crustal plates each moves on to the plastic asthenosphere more or less independantly.

===**History**** Plate tectonic theory had its beginning in 1915. Alfred Wegner (1880-1930) proposed his theory of "continental drift". His theory explained why the outline of many coastlines fit together like a puzzle. He was the first to realize that earths surface has changed over time and that continents aren't where they always were. Fossils were also found on other continents from where there normally found. These studies seem to show that the earth lithosphere has been moving over time. Wegners theories were very controversial because he did not have an explanation and his theory was later disproved but this was the first time continental drift had been introduced to the scientific community. **

===


===

===

**Continental Drift**
The tectonic plate theory builds on the older concepts of continental drift.Continental drift was first, before the tectonic plate theory.