Mnemonic: DUDE

For how the Grand Canyon (and many other canyons) formed

DUDE   

Dude!  Be careful!
Dude, move away from the edge!

D: Depostion/ Deposit
U: Uplift
D: Down Cutting
E: Erosion

Further explanation:
D: Deposit -- Layers of materials were deposited. As they grew thick and heavy, they were pressing the lower layers into rock. 
U: Uplift -- The Pacific Plate (Tectonic Plate) slid under the North American Plate, causing uplift and forming the Rocky Mountains.
D: Down Cutting:  The river flowing down, cut down through the layers that had been deposited.
E:  Erosion:  Other eroding forces helped to form the canyon, including rain and other precipitation, smaller streams (side-streams and debris flows), water seeping into cracks then freezing and expanding to break rock into smaller pieces, wind.



To learn more: 
deposition

  (děp'ə-zĭsh'ən)    

1. The accumulation or laying down of matter by a natural process, as the laying down of sediments in a river or the accumulation of mineral deposits in a bodily organ.

Videos about the formation of the Grand Canyon: 

https://www.youtube.com/watch?v=fGfPp-oOrNI
https://www.youtube.com/watch?v=ktf73HNZZGY

Sign into Pioneer Online Library [http://pioneer.uen.org/k12/  username: pioneer, password: student] and see this article:
http://discoverer.prod.sirs.com/discoweb/disco/do/article?urn=urn%3Asirs%3AUS%3BARTICLE%3BART%3B0000285878