By Prof. Liwayway Memije-Cruz

Plate Tectonics

The Continental Drift TheoryAccording to Alfred Wegener had once been joined together forming a single supercontinent landmass called Pangaea that divided into individual continents as they are now.

The Seafloor Spreading Theory

This theory states that the oceanfloor are spreading outward from vast underwater ridges. This was proposed by an American geologist named Harry H. Hess in early 1960’s.

Seafloor Spreading

What is Plate Tectonics Theory?Plate tectonics is the theory that the outer rigid

layer of the earth (the lithosphere) is divided into a couple of dozen "plates" that move around across the earth's surface relative to each other, like slabs of ice on a lake.

TYPES OF PLATE BOUNDARYDivergent boundary or divergent plate boundary

(also known as a constructive boundary or an extensional boundary) is a linear feature that exists between two tectonic plates that are moving away from each other.

Convergent boundary, also known as a destructive plate boundary (because of subduction), is an actively deforming region where two (or more) tectonic plates or fragments of the lithosphere move toward one another and collide.

Transform boundary (or conservative boundary) is where two of the tectonic plates slide alongside each other. When this happens, the scraping of the two plates causes earthquakes. And since these faults neither create nor destroy lithosphere, is a type of fault whose relative motion is predominantly horizontal in either sinistral or dextral direction.