Note Set 4
by Sam Robbins
To understand plate tectonics we have to think about the Earths crust. One way to think about it is what the shell of the Earth has in common with a shell of an egg. A way that they are similar is the ratio of a shell to an Egg is like the ratio of the crust to the Earth in thickness to diameter.
Another thing to think about when you’re trying to understand the theory of plate tectonics is what drives the tectonic plates. One way is the process of the Earth cooling which is supported by the evidence of convection currents. Convection is the heating, cooling circulation process of fluids. A couple of examples of that are the flow of mantle material in the Earth and the flow of air in the atmosphere. The sources of the heat from inside the Earth are radioactive decay from uranium and left- over heat from the formation of the Earth.
The last thing to think about when you’re trying to understand plate tectonics is to understand what are tectonic plates. Tectonic plates are a part of the Earths lithosphere which is the components of the crust. Tectonic plates are also the outermost layer of the lithosphere. The two different types of tectonic plates are the continental plates and the oceanic plates. In total there are about a dozen tectonic plates that exist today. The last thing to talk about is plate boundaries. Plate boundaries are a location where two plates meet they are marked by earthquakes and volcanoes. The evidence for plate boundaries are the worldwide location of most earthquakes and volcanoes.