Cooling from the bottom up is evidenced by collonnade jointing which occurs when coarser basalt cools. The Columbia River Flood Basalt Province forms a plateau of 164,000 square kilometers between the Cascade Range and the Rocky Mountains. Glass, plagioclase and augite are the most common minerals in these basalts. Map of Grande Ronde Basalt coverage area. Figure 7. Another set of papers explores the tectonic and structural development of the Columbia River flood basalt province (CRFBP), a constituent part of the CRBG. The Columbia River Basalt Group covers an area of more than 210,000 km2 with an estimated volume of 210,000 km3. The formation was deposited between 16 and 15 million years ago and is very limited in volume and is mostly covered by more recent flows. The newest idea of lava emplacement comes from Self and Thordarson (1996). Some geologists believe that the Picture Gorge Basalt was emplaced during the same time as the Grande Ronde Basalt, leading them to believe that the Picture Gorge Basalt originated from a different source than the overlying Grande Ronde Basalt. According to Shaw and Swanson (1970), the amount of crystallization does not change from the fissure zone to the farthest reaches of each lobe of lava. Publishing Organization: Geological Society of America Series and Number: Special Paper 239 [386 p.] Publication Date: 1989 Cross Section: Yes North Latitude: 48° 0' 0" N (48.0000) South Latitude: 44° 0' 0" N (44.0000) Layers of volcanic ash are also present. Rocks of the Grande Ronde Basalt dominate the Columbia River flood basalt province, to form over 60% of the total volume of the CRBG (Camp et al., 2003). Figure 6. While the Picture Gorge Basalt was being deposited, a period of transition occurred. School of the Environment, Washington State UniversityâTri-Cities, 2710 Crimson Way, Richland, Washington 99354, USA, Department of Geology, University of Leicester, University Road, Leicester, LE1 7RH, UK, Department of Physical Sciences, Centre for Earth, Planetary, Space and Astronomy Research, Open University, Milton Keynes, MK7 6AA, UK, Department of Earth & Planetary Science, University of California, 1156 High Street, Santa Cruz, California 95064, USA, College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, Oregon 97331, USA, Berkeley Geochronology Center, 2455 Ridge Road, Berkeley, California 94709, USA, and Department of Earth & Planetary Science, University of California, Berkeley, California 94720, USA, Department of Geology & Geophysics, Louisiana State University, Baton Rouge, Louisiana 70803, USA, Department of Geological Sciences, San Diego State University, San Diego, California 92182, USA, College of Oceanic and Atmospheric Sciences, Oregon State University, Corvallis, Oregon 97331, USA, Department of Earth and Planetary Sciences, University of California, Santa Cruz, California 95064, USA, Department of Geosciences, Oregon State University, Corvallis, Oregon 97331, USA, School of the Environment, Washington State UniversityâTri Cities, Richland, Washington 99320, USA, Department of Geological Sciences, San Diego State University, San Diego, California 92116, USA, The School of the Environment, Washington State UniversityâTri-Cities, 2710 Crimson Way, Richland, Washington 99352, USA, Department of Geological Sciences, New Mexico State University, Las Cruces, New Mexico 88003, USA, ThermoScientific, 1400 N. Pointe Parkway, West Palm Beach, Florida 33407, USA, Department of Earth Sciences, Florida International University, Miami, Florida 33199, USA, Idaho Geological Survey, University of Idaho, Moscow, Idaho 83844, USA, Geology Department, University of Hawaii at Hilo, 200 West Kawili Street, Hilo, Hawaii 96720, USA, Department of Geology, Portland State University, Portland, Oregon 97207-0751, USA, School of Earth and Environmental Sciences, Washington State University, P.O. As the lava flows, it inflates. The Columbia River Flood Basalts represent the youngest continental flood basalt province on Earth and one of the best preserved. Simplified from Reidel and others, 2003. The final paper discusses the role of basalt stratigraphy and structure in understanding the hydrogeology of the basalts. Map of Wanapum Basalt coverage area. The Saddle Mountains Basalt is even more silica rich than the Wanapum Basalt and also more deformed due compression and extensional events as the basalt cooled. 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