Lesson 1 - Understanding the Pieces

Plate Tectonics Theory

A theory that explains the different processes that cause the formation of geologic features and phenomena.

Pangaea

The supercontinent that existed about 250 million years ago, formed by the merging of all Earth's landmasses.

Lithosphere

The outermost layer of Earth composed of the upper part of the mantle and the crust.

Continental Crust

The thicker and less dense type of Earth's crust that floats over the denser and relatively thinner oceanic crust.

Plates

Fragments into which the lithosphere is divided, including large plates and small plates.

Earthquakes

The release of energy caused by collisions, rifting, or slipping between or among tectonic plates.

Seismic Waves

Waves of energy that are released during an earthquake and travel through the Earth.

Epicenter

The point on the Earth's surface directly above the location where an earthquake originates.

Mid-Atlantic Ocean Ridge

A long oceanic ridge in the Atlantic Ocean formed by plates that are pulling apart.

Subduction

The process in which one tectonic plate goes underneath another plate.

Volcano Arc

A series of volcanoes formed by the movement of melted rock from subducting plates.

Seafloor Spreading

The process by which new oceanic crust is formed through the upwelling of magma at mid-ocean ridges.

Alfred Wegener

He is a German meteorologist and geophysicist that hypothesized and suggested that the landmasses of Earth were once merged into a supercontinent known as Pangaea.