Encyclopedia  |   World Factbook  |   World Flags  |   Reference Tables  |   List of Lists     
   Academic Disciplines  |   Historical Timeline  |   Themed Timelines  |   Biographies  |   How-Tos     
Sponsor by The Tattoo Collection
Columbia River Plateau
Main Page | See live article | Alphabetical index

Columbia River Plateau

The Columbia River Plateau lies across parts of the states of Washington, Oregon, and Idaho. During late Miocene and early Pliocene times, one of the largest basaltic lava floods ever to appear on the earths surface engulfed about 63,000 square miles of the Pacific Northwest. Over a period of perhaps 10 to 15 million years lava flow after lava flow poured out, eventually accumulating to a thickness of more than 6,000 feet. As the molten rock came to the surface, the earths crust gradually sank into the space left by the rising lava. The subsidence of the crust produced a large, slightly depressed lava plain now known as the Columbia Basin or Plateau. The ancient Columbia River was forced into its present course by the northwesterly advancing lava. The lava, as it flowed over the area, first filled the stream valleys, forming dams that in turn caused impoundments or lakes. In these ancient lake beds are found fossil leaf impressions, petrified wood, fossil insects, and bones of vertebrate animals.

Portions of this article adapted from works of the United States Government, which are in the public domain

External links

USGS Page on Columbia Plateau
Regions of Idaho
Rocky Mountains | Columbia River Plateau | Inland Empire | Basin and Range Province
Boise metropolitan area
Largest Cities
Ammon | Blackfoot | Boise | Burley | Caldwell | Chubbuck | Coeur D'Alene | Eagle | Garden City | Hayden | Idaho Falls | Jerome | Lewiston | Meridian | Moscow | Mountain Home | Nampa | Pocatello | Post Falls | Rexburg
Counties
Ada | Adams | Bannock | Bear Lake | Benewah | Bingham | Blaine | Boise | Bonner | Bonneville | Boundary | Butte | Camas | Canyon | Caribou | Cassia | Clark | Clearwater | Custer | Elmore | Franklin | Fremont | Gem | Gooding | Idaho | Jefferson | Jerome | Kootenai | Latah | Lemhi | Lewis | Lincoln | Madison | Minidoka | Nez Perce | Oneida | Owyhee | Payette | Power | Shoshone | Teton | Twin | Valley | Washington |

{| style="margin:0 auto" align=center id=toc
State of
Oregon
   
Regions
Columbia River Gorge and Plateau | Eastern Oregon | Inland Empire | Mt. Hood Corridor | Oregon Coast | Western Oregon | Willamette Valley
Counties     Largest Cities (full list)
Baker | Benton | Clackamas | Clatsop | Columbia | Coos | Crook | Curry | Deschutes | Douglas | Gilliam | Grant | Harney | Hood River | Jackson | Jefferson | Josephine | Klamath | Lake | Lane | Lincoln | Linn | Malheur | Marion | Morrow | Multnomah | Polk | Sherman | Tillamook | Umatilla | Union | Wallowa | Wasco | Washington | Wheeler | Yamhill     Albany | Beaverton | Bend | Corvallis | Eugene | Grants Pass | Gresham | Hillsboro | Keizer | Lake Oswego | McMinnville | Medford | Milwaukie | Oregon City | Portland | Salem | Springfield | Tigard | Tualatin | West Linn
{| style="margin:0 3em 0 3em" id=toc {| id="toc" style="margin: 0 2em 0 2em;" ! style="background:#ccccff" align="center" width="100%" |
 
Washington || |- |align=center colspan=2| Regions: Central Washington | Columbia River Plateau | Eastern Washington | Inland Empire | Kitsap Peninsula | Olympic Peninsula | Okanogan Country | Palouse | Puget Sound | San Juan Islands | Western Washington | Yakima Valley |- |align=center colspan=2| Largest Cities: Auburn | Bellevue | Bellingham | Bremerton | Edmonds | Everett | Federal Way | Kennewick | Kent | Kirkland | Lakewood | Olympia | Redmond | Renton | Richland | Seattle | Shoreline | Spokane | Tacoma | Vancouver | Yakima |- |align=center| Counties: Adams | Asotin | Benton | Chelan | Clallam | Clark | Columbia | Cowlitz | Douglas | Ferry | Franklin | Garfield | Grant | Grays Harbor | Island | Jefferson | King | Kitsap | Kittitas | Klickitat | Lewis | Lincoln | Mason | Okanogan | Pacific | Pend Oreille | Pierce | San Juan | Skagit | Skamania | Snohomish | Spokane | Stevens | Thurston | Wahkiakum | Walla Walla | Whatcom | Whitman | Yakima