Create an account
the theory that the Earth's crust is made of huge, slowly moving slabs of rock called plates
an area that rises steeply at least 2,000 feet above surrounding land; usually wide at the bottom and rising to a narrow peak or ridge. Everest is one of the most famous examples
according to scientific theory, a single landmass that broke apart to form today's separate continents; thought to have existed about 180 million years ago.
a triangular-shaped plain at the mouth of a river, formed when sediment is deposited by flowing water.
a large, mostly flat area that rises above the surrounding land; at least one side has a steep slope
a large stream of water of natural origin which drains an area of land and flows into another river or body of water
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 and try again
Reload the page to try again!Reload
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