Advertisement Upgrade to remove ads


a scientist who studies the forces that make and shape planet earth


a lump or mass of hard consolidated mineral matter


The scientific study of the origin, history, and structure of the earth.

Constructive Force

a force that builds up mountains and landmasses on Earth's surface

Destructive Force

a force that slowly wears away mountains and other features on the surface of Earth


one of the large landmasses of the earth

Seismic Wave

A vibration that travels through earth carrying the energy released during an earthquake


the force applied to a unit area of surface


the outer layer of the Earth


A dark, dense, igneous rock with a fine texture, found in oceanic crust.


A usually light colored igneous rock that is found in continental crust


the layer of the earth between the crust and the core


the solid, outer layer of the earth that consists of the crust and the rigid upper part of the mantle


The solid, plastic layer of the mantle beneath the lithosphere; made of mantle rock that flows very slowly, which allows tectonic plates to move on top of it

Outer Core

the liquid layer of the Earth's core that lies beneath the Mantle and surrounds the inner Core

Inner Core

a dense sphere of solid iron and nickel at the center of Earth

Mid-Ocean Ridge

An undersea mountain chain where new ocean floor is produced; a divergent plate boundary.


a measuring instrument that sends out an acoustic pulse in water and measures distances in terms of the time for the echo of the pulse to return

Sea- Floor Spreading

when two oceanic plates pull apart, magma rises and new crust is formed

Deep-Ocean Trench

a deep valley along the ocean floor beneath which oceanic crust slowly sinks toward the mantle


the process by which oceanic crust sinks beneath a deep-ocean trench and back into the mantle at a convergent plate boundary


a rigid layer of the Earth's crust that is believed to drift slowly

Scientific Theory

A well tested explanation for a wide range of observations or experimental results

Plate Tectonics

the theory that pieces of Earth's lithosphere are in constant motion, driven by convection currents in the mantle

Transform Boundary

the boundary between tectonic plates that are sliding past each other horizontally

Divergent Boundary

the boundary between two tectonic plates that are moving away from each other

Convergent Boundary

A tectonic plate boundary where two plates collide, come together, or crash into each other.

Continental Drift

the hypothesis that states that the continents once formed a single landmass, broke up, and drifted to their present locations

Please allow access to your computer’s microphone to use Voice Recording.

Having trouble? Click here for help.

We can’t access your microphone!

Click the icon above to update your browser permissions above and try again


Reload the page to try again!


Press Cmd-0 to reset your zoom

Press Ctrl-0 to reset your zoom

It looks like your browser might be zoomed in or out. Your browser needs to be zoomed to a normal size to record audio.

Please upgrade Flash or install Chrome
to use Voice Recording.

For more help, see our troubleshooting page.

Your microphone is muted

For help fixing this issue, see this FAQ.

Star this term

You can study starred terms together

NEW! Voice Recording