How has the Surface oF Earth Changed through Time?
Watch these two videos which show the history of plate tectonics from 750 million years ago to today, and a shorter 240 million year history followed by an extrapolation of plate tectonics 250 million years into the future:
How do we know this?
These animations are plate reconstructions based upon ideas and data from geologic maps. Each geologic map is a visual representation of a hypothesis, or testable explanation, of the geologic events that location has experienced.
One of the goals of this module is to interpret the geologic maps in terms of plate tectonic forces: compression, tension, or shear (see Motion at Plate Boundaries and Geologic Structures and Plate Tectonics).
These interpretations are used to determine the type of plate boundar(ies) which existed in the past.