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Mascall Formation
The Mascall Formation is a Miocene geologic formation found along the John Day River, John Day River Valley of Oregon, in the Western United States. Description The formation is described in ''Geologic Formations of Eastern Oregon'' (1972) as follows: "The Mascall Formation consists of a maximum of 2,000 feet of fluvial sandstone, ash, light colored water-laid tuff, and well-rounded Conglomerate (geology), conglomerate. The conglomerate is increasingly coarse-grained towards the east and is composed of clasts of chert, metavolcanics, and rhyolite. Within the Mascall Formation is a widespread ignimbrite unit which consists of 97 to 99 percent glass shards and minor amounts of anorthoclase, quartz, magnetite, zircon, and clinopyroxene. That 10 percent of the anorthoclase consists of orthoclase is considered to be a unique feature of the unit by Davenport (1970)."''Geologic Formations of Eastern Oregon'' (East of longitude 121°30'), 1972. John D. Beaulieu.Bulletin 73 Oregon De ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sedimentary
Sedimentary rocks are types of rock (geology), rock that are formed by the accumulation or deposition of mineral or organic matter, organic particles at Earth#Surface, Earth's surface, followed by cementation (geology), cementation. Sedimentation is the collective name for processes that cause these particles to settle in place. The particles that form a sedimentary rock are called sediment, and may be composed of detritus (geology), geological detritus (minerals) or detritus, biological detritus (organic matter). The geological detritus originated from weathering and erosion of existing rocks, or from the solidification of molten lava blobs erupted by volcanoes. The geological detritus is transported to the place of deposition by water, wind, ice or Mass wasting, mass movement, which are called agents of denudation. Biological detritus was formed by bodies and parts (mainly shells) of dead aquatic organisms, as well as their fecal mass, suspended in water and slowly piling up on ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
