Editing Columbia Basin Project (section)

==Geology==
[[Image:Drum-Heller-Channels.jpg|thumb|left|300px|Drumheller Channels, {{convert|10|mi|km}} south of [[Potholes Reservoir]], are examples of [[channeled scablands]]]]
The [[Columbia River Drainage Basin|Columbia Basin]] in Central Washington is fertile due to its loess soils, but large portions are a near [[desert]], receiving less than {{convert|10|in|mm|spell=in}} of rain per year. The area is characterized by huge deposits of [[flood basalt]], thousands of feet thick in places, laid down over a period of approximately 11 million years, during the [[Miocene]] epoch.<ref>Orr (1996), pg. 288.</ref> These flood basalts are exposed in some places, while in others they are covered with thick layers of loess.

During the last ice age [[glacier]]s shaped the landscape of the [[Columbia River Plateau]]. Ice blocked the Columbia River near the north end of Grand Coulee, creating glacial lakes [[Glacial Lake Columbia|Columbia]] and Spokane. Ice age glaciers also created [[Glacial Lake Missoula]], in what is now [[Montana]]. Erosion allowed glacial Lake Columbia to begin to drain into what became Grand Coulee, which was fully created when glacial Lake Missoula along with glacial Lake Columbia catastrophically emptied.<ref>Orr (1996), pg. 305.</ref> This flood event was one of several known as the [[Missoula Floods]]. Unique erosion features, called [[channeled scablands]], are attributed to these amazing floods.