I’m trying to learn for my Geology class and I’m stuck. Can you help?
There are a lot of tedious steps, but once finished it is fairly simple:
Plate tectonics is a unifying framework for understanding the dynamic geology of the Earth. The theory posits that the outermost layers of the Earth (the crust and uppermost mantle) make up the brittle lithosphere of the Earth. The lithosphere is broken up into a number of thin plates, which move on top of the asthenosphere (middle mantle). The asthenosphere is solid, but flows plastically over geologic time scales. Plate interiors are relatively stable, and most of the tectonic action (earthquakes, volcanism) takes place where plates meet – where they collide at convergent boundaries, move away from one another at divergent boundaries, or slide past one another at transform boundaries.
Reconstructions of the Earth's tectonic plate locations through time are available, for example, at:
http://www.scotese.com/newpage13.htm (Links to an external site.)
http://www.ucmp.berkeley.edu/geology/tectonics.html (Links to an external site.)
But how do we define plates and plate boundaries? On what are plate reconstructions and animations based? How do we know plates are moving, how can we track their positions in the past, and how can we predict their positions in the future?
To answer these questions, this assignment guides you through an examination of patterns on Earth – the topography of the earth's surface above sea level, the bathymetry of the ocean floor below sea level, and the distribution of earthquakes and volcanic rock ages. These patterns reveal plate boundaries, just as they did for geologists first developing plate tectonic theory in the 1960s. You'll then use geologic data to determine long-term average plate motions, to predict how our dynamic planet will change in the future.