2 Geothermal

Earth Science Unit 2

Plate Tectonics

The theory that Earth’s surface is broken into large pieces (plates) that move around slowly over time. 

Convergent Boundary

A place where two tectonic plates are moving toward each other, often causing mountains or volcanoes.

Divergent Boundary

A place where two tectonic plates slide past each other sideways, usually causing earthquakes.

Transform Boundary

A place where two tectonic plates slide past each other sideways, usually causing earthquakes.

Subduction Zone

A place where one tectonic plate is pushed under another, usually creating deep trenches and volcanoes.

Mid- Ocean Ridge

A long chain of mountains under the ocean, where new crust is formed as plates pull apart. 

Oceanic Crust

The thinner, denser part of Earth’s crust that makes up the continents.

Continental Crust

The thicker, less dense part of Earth’s crust that makes up the continents.

Lithosphere

The rigid outer layer of Earth that includes the crust and the uppermost mantle. This layer forms the tectonic plates.

Asthenosphere

The softer, flowing layer of the mantle that allows the tectonic plates to move on top of it. 

Continental Drift

The idea that Earth’s continents have slowly moved across the planet over time due to plate tectonics.

Earth’s Magnetic Field

The invisible field made by Earth’s spinning molten iron core, recorded in rocks and occasionally reversing direction.

Convection

The movement of heat through a fluid (like the mantle) where hot material rises and cooler material sinks, creating a flow that pushes tectonic plates. 

Supercontinent

A giant landmass made up of most or all of Earth’s continents joined together in the past.