What is Grand Coulee?
{{Orphan|date=December 2010}} [[Image:Grand coulee below dry falls.JPG|thumb|right|300px|Grand Coulee, below [[Dry Falls]]. The layering effect of periodic basalt lava flows is visible.]] The '''Grand Coulee''' used to be a river in the [[U.S. state]] of [[Washington]]. This dry river stretches for sixty miles from the [[Grand Coulee Dam]] to [[Soap Lake]]. A feature known as [[Dry Falls]] divides the Coulee into two parts. Dry Falls is thought to be the remains of the largest waterfall ever, two or three times higher than [[Niagara Falls]].<ref name=dry>[http://www.gonorthwest.com/washington/northeast/Dry_Falls.htm Dry Falls], GoNorthWest.com, accessed November 2009</ref> ==Geological history== The Grand Coulee is [[granite]] bedrock which is 40 to 60&nbsp; million years old. The volcanic [[basalt]] is {{convert|2000|m|ft}} thick. The coulee is said to have been made when the [[Columbia River]] was blocked by a large [[glacier]]. At the end of the last ice age the Columbia River went back to its old route and left the coulee. The coulee is a mile wide and was formed by a river that now flows a different way.<ref>[http://www.bpa.gov/Power/pl/columbia/4-geology.htm The Geologic Story of the Columbia Basin] {{Webarchive|url=https://web.archive.org/web/20091105170525/http://www.bpa.gov/Power/pl/columbia/4-geology.htm |date=2009-11-05 }}, bpa.gov, November 2009</ref> ==Modern Uses== [[File:Grand-Coulee-Steamboat-RockPB110055.JPG|thumb|left|Banks Lake]] The area surrounding the Grand Coulee is shrub land. It has a rainfall of twelve inches per year. The Lower Grand Coulee contains the Park, Blue, Alkali, Lenore, and Soap lakes. Until recently, the Upper Coulee was dry. The ''Columbia Basin Project'' dammed the river in 1952. It used the Grand Coulee as an [[irrigation]] network. The Upper Grand Coulee was dammed and made ''Banks Lake''. The lake is filled by pumps from the Grand Coulee Dam. Banks Lake feeds a hundred-mile (160&nbsp;km) irrigation system. ==References== {{commonscat}} <references/> [[Category:Ge