Its canyon was carved out by a fork in the catastrophic Missoula Floods of the previous ice age, which spilled over the northern Columbia Plateau and flowed into the Snake River, eroding the river's present course in a few thousand years.
Course
The Palouse River flows from northernIdaho into southeast Washington through the Palouse region, named for the river.
From Colfax, the river meanders west and ends up in the lower Snake River southwest of Hooper, but not before dropping two hundred feet (60 m) over Palouse Falls. The Palouse River enters the Snake River below the Little Goose Dam and above the Lower Monumental Dam.
Basin and discharge
The Palouse River's drainage basin is 3,303 square miles (8,550 km2) in area.[2] Its mean annual discharge, as measured by USGS gage 13351000 at Hooper (river mile 19.6), is 599 cubic feet per second (17 m3/s), with a maximum daily recorded flow of 27,800 cu ft/s (787 m3/s), and a minimum of zero flow.[3]
The ancestral Palouse River flowed through the now-dry Washtucna Coulee directly into the Columbia River. The present-day canyon was created when the Missoula Floods overtopped the northern drainage divide of the ancestral Palouse River, diverting it to the current course to the Snake River by eroding a new, deeper channel.[7][10]
The area is characterized by interconnected and hanging flood-created coulees, cataracts, plunge pools, kolk created potholes, rock benches, buttes and pinnacles typical of scablands.[9]
^U.S. Geological Survey. National Hydrography Dataset high-resolution flowline data. The National Map, accessed May 3, 2011
^ abCarson, Robert J.; Pogue, Kevin R. (1996). Flood Basalts and Glacier Floods:Roadside Geology of Parts of Walla Walla, Franklin, and Columbia Counties, Washington. Washington State Department of Natural Resources (Washington Division of Geology and Earth Resources Information Circular 90). ISBN none.
^Alt, David (2001). Glacial Lake Missoula & its Humongous Floods. Mountain Press Publishing Company. ISBN0-87842-415-6.
^ abBjornstad, Bruce (2006). On the Trail of the Ice Age Floods: A Geological Guide to the Mid-Columbia Basin. Keokee Books; Sandpoint, Idaho. ISBN978-1-879628-27-4.
^Alt, David & Hyndman, Donald (1984). Roadside Geology of Washington. Mountain Press Publishing Company. ISBN0-87842-160-2.
External links
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