If all of this is new to you, here's the short version. The theory of plate tectonics says that the crust of the earth is not whole and unmoving, like the surface of a ball. It's more like a cracked egg shell. Between the cracks are large pieces of the surface called plates. These plates are very slowly moving--about an inch per year.

The edges of the plates are said to be constantly but very slowly emerging as liquid rock from earth's hot core. Versions of this have been observed on the ocean floor, where lava boils up into the water and cools into hard rock.

Plate tectonic theory says that earthquakes and volcanoes are caused by shifts in the earth's plates most often occur at or near the plate boundaries.

The blue and green dots represent locations of earthquakes and volcanoes. Notice, some plate edges almost match the outlines of continents. They meet at the western edge of North and South America (to the right of center).

In the picture below, can you see five continents?

Notice, on the right, the plate outlines that appear to match the outline of the African continent. Are there any others that do that?

Why is that ? Does that suggest any ideas to you?

Continue On

Main | Basic_Ideas | Gyro | Readings