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Wallula Gap
Wallula Gap () is a large water gap of the Columbia River in the northwest United States in southeast Washington. It cuts through the Horse Heaven Hills basalt anticlines in the Columbia River Basin, just south of the confluence of the Walla Walla and Columbia rivers. It has been recognized as a National Natural Landmark by the National Park Service as a site that provides an important illustration of the geological history of the United States. Geology Flood basalts In southeastern Washington, eastern Oregon, and southern Idaho, flood basalt flows of extremely fluid basaltic lava spread in all directions from long fissures, building broad fields of gently sloping lava that spread widely over great distances. Along the Snake River in Idaho, and the Columbia River in Washington and Oregon, these lava flows have been extensively exposed by erosion (with extensive displays of columnar basalt), and measure almost 2 km (1.24 mi) in total thickness. The basalts fl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wallula, Washington
Wallula () is a census-designated place (CDP) in Walla Walla County, Washington, United States. The population was 179 at the 2010 census. History The Lewis and Clark Expedition reached this area April 27, 1806, on their return journey from the Pacific. The expedition spent three days at the village of Chief Yallept and his tribe of Walla Walla people (relatives of the Nez Perce), in the company of about a hundred Yakama people. Meriwether Lewis estimated the total of Native American people at around 550. There the expedition learned of an overland route to the Nez Perce homelands, which shortened their route by some eighty miles. During David Thompson's 1811 voyage down the Columbia River, he camped at the Snake River confluence on July 9, 1811. There he erected a pole and notice claiming the country for Great Britain and stating the intention of the North West Company to build a trading post at the site. European settlement of the area began in 1818, when the North West Compa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Idaho
Idaho ( ) is a state in the Pacific Northwest region of the Western United States. To the north, it shares a small portion of the Canada–United States border with the province of British Columbia. It borders the states of Montana and Wyoming to the east, Nevada and Utah to the south, and Washington and Oregon to the west. The state's capital and largest city is Boise. With an area of , Idaho is the 14th largest state by land area, but with a population of approximately 1.8 million, it ranks as the 13th least populous and the 7th least densely populated of the 50 U.S. states. For thousands of years, and prior to European colonization, Idaho has been inhabited by native peoples. In the early 19th century, Idaho was considered part of the Oregon Country, an area of dispute between the U.S. and the British Empire. It officially became U.S. territory with the signing of the Oregon Treaty of 1846, but a separate Idaho Territory was not organized until 1863, instead ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lake Condon
Lake Condon was a temporary lake in the Pacific Northwest region of North America, formed periodically by the Missoula Floods from 15,000 to 13,000 BC. The restricted flow of waters from cataclysmic floods from Glacial Lake Missoula, and pluvial Lake Bonneville through the constriction of the Wallula Gap in the Horse Heaven Hills flowed into south-central Washington and north-central Oregon, and were backed up by the Columbia River Gorge, forming Lake Condon. The water remained for a period of 5–7 days before the flood waters drained through the Columbia River Gorge. Lake Condon reached an elevation of about 1200 feet above sea level (today's sea level) before subsiding. Lake Condon also flooded the Umatilla and John Day river valleys. Glacial Lake Missoula During the last Ice Age (18,000 to 12,000 years ago), and in multiple previous Ice Ages, cataclysmic floods inundated portions of the Pacific Northwest from Glacial Lake Missoula, pluvial Lake Bonneville, and perhaps f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Missoula Floods
The Missoula floods (also known as the Spokane floods or the Bretz floods or Bretz's floods) were cataclysmic glacial lake outburst floods that swept periodically across eastern Washington and down the Columbia River Gorge at the end of the last ice age. These floods were the result of periodic sudden ruptures of the ice dam on the Clark Fork River that created Glacial Lake Missoula. After each ice dam rupture, the waters of the lake would rush down the Clark Fork and the Columbia River, flooding much of eastern Washington and the Willamette Valley in western Oregon. After the lake drained, the ice would reform, creating Glacial Lake Missoula again. These floods have been researched since the 1920s. During the last deglaciation that followed the end of the Last Glacial Maximum, geologists estimate that a cycle of flooding and reformation of the lake lasted an average of 55 years and that the floods occurred several times over the 2,000-year period between 15,000 and 13,000 year ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Channeled Scablands
The Channeled Scablands are a relatively barren and soil-free region of interconnected relict and dry flood channels, coulees and cataracts eroded into Palouse loess and the typically flat-lying basalt flows that remain after cataclysmic floods within the southeastern part of Washington.Neuendorf, K.K.E., J.P. Mehl, Jr., and J.A. Jackson, eds. (2005) ''Glossary of Geology'' (5th ed.). Alexandria, Virginia, American Geological Institute. 779 pp. The Channeled Scablands were scoured by more than 40 cataclysmic floods during the Last Glacial Maximum and innumerable older cataclysmic floods over the last two million years. These floods were periodically unleashed whenever a large glacial lake broke through its ice dam and swept across eastern Washington and down the Columbia River Plateau during the Pleistocene epoch. The last of the cataclysmic floods occurred between 18,200 and 14,000 years ago.Balbas, A.M., Barth, A.M., Clark, P.U., Clark, J., Caffee, M., O'Connor, J., Baker, V ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Snake River
The Snake River is a major river of the greater Pacific Northwest region in the United States. At long, it is the largest tributary of the Columbia River, in turn, the largest North American river that empties into the Pacific Ocean. The Snake River rises in western Wyoming, then flows through the Snake River Plain of southern Idaho, the rugged Hells Canyon on the Oregon–Idaho border and the rolling Palouse Hills of Washington (state), Washington, emptying into the Columbia River at the Tri-Cities, Washington, Tri-Cities in the Columbia Basin of Eastern Washington. The Snake River drainage basin encompasses parts of six U.S. states (Idaho, Washington, Oregon, Utah, Nevada, and Wyoming) and is known for its varied geologic history. The Snake River Plain was created by a volcanic hotspot (geology), hotspot which now lies underneath the Snake River headwaters in Yellowstone National Park. Gigantic glacial-retreat flooding episodes during the previous Last glacial period, Ice Ag ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Salmon River (Idaho)
The Salmon River, also known as "The River of No Return", is a river located in the U.S. state of Idaho in the western United States. It flows for through central Idaho, draining a rugged, thinly populated watershed of . The river drops more than from its headwaters, near Galena Summit above the Sawtooth Valley in the Sawtooth National Recreation Area, to its confluence with the Snake River. Measured at White Bird, its average discharge is . The Salmon River is the longest undammed river in the contiguous United States and the longest within a single state outside Alaska. Settlements located along the Salmon River include Stanley, Clayton, Challis, Salmon, Riggins, and White Bird. Redfish Lake and Little Redfish Lake, which flow into the river via Redfish Lake Creek, are the termini of the longest Pacific sockeye salmon migration in North America. The lower half of the river provides the time zone boundary for the state, with northern Idaho on Pacific Time an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Blue Mountains (Oregon)
The Blue Mountains are a mountain range in the northwestern United States, located largely in northeastern Oregon and stretching into extreme southeastern Washington. The range has an area of about , stretching east and southeast of Pendleton, Oregon, to the Snake River along the Oregon–Idaho border. The Blue Mountains cover ten counties across two states; they are Union, Umatilla, Grant, Baker, Wallowa and Harney counties in Oregon, and Walla Walla, Columbia, Garfield and Asotin counties in Washington. The mountains are unique as the home of the world's largest living organism, a subterranean colonial mycelial mat of the fungus ''Armillaria ostoyae''. The Blue Mountains were named after the color of the mountains when seen from a distance. Geology The Blues are uplift mountainscbgwma.orThe Columbia River Basalt Group , Continental flood basalt flows , cbgwma.org accessdate: February 8, 2017 and contain some of the oldest rocks in Oregon. Rocks as old as 400 million yea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shear (geology)
Boudinaged quartz vein (with strain fringe) showing ''Fault (geology)">sinistral shear sense'', Starlight Pit, Fortnum Gold Mine, Western Australia In geology, shear is the response of a rock to deformation usually by compressive stress and forms particular textures. Shear can be homogeneous or non-homogeneous, and may be pure shear or simple shear. Study of geological shear is related to the study of structural geology, rock microstructure or rock texture and fault mechanics. The process of shearing occurs within brittle, brittle-ductile, and ductile rocks. Within purely brittle rocks, compressive stress results in fracturing and simple faulting. Rocks Rocks typical of shear zones include mylonite, cataclasite, S-tectonite and L-tectonite, pseudotachylite, certain breccias and highly foliated versions of the wall rocks. Shear zone A shear zone is a tabular to sheetlike, planar or curviplanar zone composed of rocks that are more highly strained than rocks adjacent to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Columbia Plateau
The Columbia Plateau is a geologic and geographic region that lies across parts of the U.S. states of Washington, Oregon, and Idaho. It is a wide flood basalt plateau between the Cascade Range and the Rocky Mountains, cut through by the Columbia River. Geology During late Miocene and early Pliocene times, a flood basalt engulfed about of the Pacific Northwest, forming a large igneous province. Over a period of perhaps 10 to 15 million years, lava flow after lava flow poured out, ultimately accumulating to a thickness of more than 6,000 feet (1.8 km). As the molten rock came to the surface, the Earth's crust gradually sank into the space left by the rising lava. The Columbia River Basalt Group consists of seven formations: The Steens Basalt, Imnaha Basalt, Grande Ronde Basalt, Picture Gorge Basalt, Prineville Basalt, Wanapum Basalt, and Saddle Mountains Basalt. Many of these formations are subdivided into formal and informal members and flows. The subsidence of the crust ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Columbia River Basalt Group
The Columbia River Basalt Group is the youngest, smallest and one of the best-preserved continental flood basalt province on Earth, covering over mainly eastern Oregon and Washington, western Idaho, and part of northern Nevada. The basalt group includes the Steens and Picture Gorge basalt formations. Introduction During the middle to late Miocene epoch, the Columbia River flood basalts engulfed about of the Pacific Northwest, forming a large igneous province with an estimated volume of . Eruptions were most vigorous 17–14 million years ago, when over 99 percent of the basalt was released. Less extensive eruptions continued 14–6 million years ago. Erosion resulting from the Missoula Floods has extensively exposed these lava flows, laying bare many layers of the basalt flows at Wallula Gap, the lower Palouse River, the Columbia River Gorge and throughout the Channeled Scablands. The Columbia River Basalt Group is thought to be a potential link to the Chil ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
