Since  its emergence in the 1960's, plate tectonic theory

As an extra credit, :

• Must discuss at least one (1) other student's topic
•  

Student discussion:

Since  its emergence in the 1960's, plate tectonic theory has gained  wide-spread acceptance as the model of how Earth's land masses shift  over time. Plate tectonics developed historically in 1915 when Alfred Wegener proposed his theory of  "continental drift." He stated that the continents plowed through crust  of ocean basins, which would explain why the outlines of many  coastlines, such as South America and Africa, appeared to fit like  missing pieces of a jigsaw puzzle. 

There  are various types of plate boundaries such as: convergent plate  boundaries, when two collide; divergent plate boundaries, when they  spread apart; and transform boundaries, when they slide past each other.

http://scecinfo.usc.edu/education/k12/learn/plate2.htm