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Shut-in (river)
A shut-in is a type of rock formation found in streams in the Ozarks, comprising pools, rivulets, rapids and plunge pools. The term has an origin in Appalachia. Description A shut-in is a rock formation that carve through a mountain ranges, causing a complex of pools, rivulets, rapids and plunge pools. They are found in streams in the Ozarks. Shut-ins are inherently confined to a narrow valley or canyon, with the river valley widening out both above and below the formation. Because the rock resists downcutting, streams typically descend at relatively steep gradient through shut-ins, with the downstream terminus of the formation often marked by a very large plunge pool. The river becomes unnavigable at shut-ins even by canoe due to the rapids and narrow channels. Etymology The term has an origin in Appalachia, where it was used to refer to a narrow river gorge confined by resistant rock layers. Examples Johnson's Shut-Ins State Park in Missouri, with its hard rhyolite and a d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Johnsons Shutins Autumn Panorama-panini 20130126
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{{Disambiguation ...
Johnsons may refer to: * Johnsons, California, a settlement in California, US * The Johnsons, a 1992 Dutch horror film * The Johnsons, original bandname of UK punk band Pussycat and the Dirty Johnsons * The Shane Twins, a professional wrestling tag team that once competed under the name "The Johnsons" See also * Johnson, the surname * Antony and the Johnsons, an American music group * Johnsons Coach & Bus Travel Johnsons Coach & Bus Travel is a bus and coach operator based in the Warwickshire town of Henley-in-Arden. History In 1909, Jack and Blanch Johnson purchased a carrier business with one carriage and two horses in Henley-in-Arden. In 1922, the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gorge
A canyon (from ; archaic British English spelling: ''cañon''), or gorge, is a deep cleft between escarpments or cliffs resulting from weathering and the erosion, erosive activity of a river over geologic time scales. Rivers have a natural tendency to cut through underlying surfaces, eventually wearing away rock layers as sediments are removed downstream. A river bed will gradually reach a baseline elevation, which is the same elevation as the body of water into which the river drains. The processes of weathering and erosion will form canyons when the river's River source, headwaters and estuary are at significantly different elevations, particularly through regions where softer rock layers are intermingled with harder layers more resistant to weathering. A canyon may also refer to a rift between two mountain peaks, such as those in ranges including the Rocky Mountains, the Alps, the Himalayas or the Andes. Usually, a river or stream carves out such splits between mountains. Examp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sandstone
Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks. Most sandstone is composed of quartz or feldspar (both silicates) because they are the most resistant minerals to weathering processes at the Earth's surface. Like uncemented sand, sandstone may be any color due to impurities within the minerals, but the most common colors are tan, brown, yellow, red, grey, pink, white, and black. Since sandstone beds often form highly visible cliffs and other topographic features, certain colors of sandstone have been strongly identified with certain regions. Rock formations that are primarily composed of sandstone usually allow the percolation of water and other fluids and are porous enough to store large quantities, making them valuable aquifers and petroleum reservoirs. Quartz-bearing sandstone can be changed into quartzite through metamorphism, usually related to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Burden Falls Wilderness
The Burden Falls Wilderness is a 3,775-acre (15.3 km2) unit of the Shawnee National Forest. It is located in northwestern Pope County and southwestern Saline County, Illinois. The wilderness is characterized by road-less second-growth hardwood forest, punctuated by a small, seasonal waterfall on Burden Creek. ''Burden Falls'' falls 20 feet (6 m) over a sandstone ledge, and the falling creek then descends another 80 feet (25 m) in a series of cascades and cataracts. Although this is a very small waterfall by the nationwide standards of the United States, Burden Falls is one of the highest waterfalls in Illinois. Unlike most of the state, Pope County and extreme southern Illinois escaped glaciation during the Ice ages, and steep slopes display the effects of lengthy erosion. Similar geological features in other regions of Illinois were ground into oblivion by the ice. Watercourses confined by sandstone ledges, of the sort found in Burden Falls Wilderness, are locally kno ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Joint (geology)
A rock in Abisko fractured along existing joints possibly by mechanical frost weathering A joint is a break (fracture) of natural origin in a layer or body of rock that lacks visible or measurable movement parallel to the surface (plane) of the fracture ("Mode 1" Fracture). Although joints can occur singly, they most frequently appear as joint sets and systems. A ''joint set'' is a family of parallel, evenly spaced joints that can be identified through mapping and analysis of their orientations, spacing, and physical properties. A ''joint system'' consists of two or more intersecting joint sets. The distinction between joints and faults hinges on the terms ''visible'' or ''measurable,'' a difference that depends on the scale of observation. Faults differ from joints in that they exhibit visible or measurable lateral movement between the opposite surfaces of the fracture ("Mode 2" and "Mode 3" Fractures). Thus a joint may be created by either strict movement of a rock la ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Black River (Arkansas)
Black River is a common name for streams and communities around the world: in Spanish and Portuguese, ''Rio Negro''; in French, ''Rivière Noire''; in Turkish, ''Kara Su''; in Serbo-Croatian, ''Crna Reka'', Црна Река or ''Crna Rijeka'', Црна Ријека; in Macedonian, Црна Река, ''Crna Reka''. Streams Africa * Bafing River, also known as ''Black River'' * Black River (Cape Town) * Niger River, named by European mapmakers during the Middle Ages, perhaps from Latin ''niger'' "black" Australia * Black River (Queensland) * Black River (Tasmania) * Black River (Victoria) Brazil and Colombia * Black River (Amazon), known as Rio Negro in Portuguese and Río Negro or Río Guainía in Spanish Canada * Black River (Newfoundland and Labrador) * Black River (New Brunswick) * Black River (Ontario), listing eight rivers of the name * Black River (Portneuf), Quebec * Black River (Vancouver Island) * Noire River (Ottawa River tributary), Quebec, English tr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dike (geology)
A dike or dyke, in Geology, geological usage, is a sheet of rock that is formed in a Fracture (geology), fracture of a pre-existing rock body. Dikes can be either Intrusive rock, magmatic or Sedimentary rock, sedimentary in origin. Magmatic dikes form when magma flows into a crack then solidifies as a sheet intrusion, either cutting across layers of rock or through a contiguous mass of rock. Clastic dikes are formed when sediment fills a pre-existing crack.Essentials of Geology, 3rd Ed, Stephen Marshak Magmatic dikes A magmatic dike is a sheet of igneous rock that cuts across older rock beds. It is formed when magma fills a fracture in the older beds and then cools and solidifies. The dike rock is usually more resistant to weathering than the surrounding rock, so that erosion exposes the dike as a natural wall or ridge. It is from these natural walls that dikes get their name. Dikes preserve a record of the fissures through which most mafic magma (fluid magma low in silica) reac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diabase
Diabase (), also called dolerite () or microgabbro, is a mafic, holocrystalline, subvolcanic rock equivalent to volcanic basalt or plutonic gabbro. Diabase dikes and sills are typically shallow intrusive bodies and often exhibit fine-grained to aphanitic chilled margins which may contain tachylite (dark mafic glass). ''Diabase'' is the preferred name in North America, while ''dolerite'' is the preferred name in the rest of the English-speaking world, where sometimes the name ''diabase'' refers to altered dolerites and basalts. Some geologists prefer to avoid confusion by using the name ''microgabbro''. The name ''diabase'' comes from the French ', and ultimately from the Greek - meaning "act of crossing over, transition". Petrography Diabase normally has a fine but visible texture of euhedral lath-shaped plagioclase crystals (62%) set in a finer matrix of clinopyroxene, typically augite (20–29%), with minor olivine (3% up to 12% in olivine diabase), magnetite (2%), an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rhyolite
Rhyolite ( ) is the most silica-rich of volcanic rocks. It is generally glassy or fine-grained (aphanitic) in texture, but may be porphyritic, containing larger mineral crystals (phenocrysts) in an otherwise fine-grained groundmass. The mineral assemblage is predominantly quartz, sanidine, and plagioclase. It is the extrusive equivalent to granite. Rhyolitic magma is extremely viscous, due to its high silica content. This favors explosive eruptions over effusive eruptions, so this type of magma is more often erupted as pyroclastic rock than as lava flows. Rhyolitic ash-flow tuffs are among the most voluminous of continental igneous rock formations. Rhyolitic tuff has been extensively used for construction. Obsidian, which is rhyolitic volcanic glass, has been used for tools from prehistoric times to the present day because it can be shaped to an extremely sharp edge. Rhyolitic pumice finds use as an abrasive, in concrete, and as a soil amendment. Description Rhyolite i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Downcutting
Downcutting, also called erosional downcutting, downward erosion or vertical erosion is a geological process by hydraulic action that deepens the channel of a stream or valley by removing material from the stream's bed or the valley's floor. The speed of downcutting depends on the stream's ''base level'', the lowest point to which the stream can erode. Sea level is the ultimate base level, but many streams have a higher "temporary" base level because they empty into another body of water that is above sea level or encounter bedrock that resists erosion. A concurrent process called lateral erosion refers to the widening of a stream channel or valley. When a stream is high above its base level, downcutting will take place faster than lateral erosion; but as the level of the stream approaches its base level, the rate of lateral erosion increases. This is why streams in mountainous areas tend to be narrow and swift, forming V-shaped valleys, while streams in lowland areas tend to be ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rock Formation
A rock formation is an isolated, scenic, or spectacular surface rock outcrop. Rock formations are usually the result of weathering and erosion sculpting the existing rock. The term ''rock formation'' can also refer to specific sedimentary strata or other rock unit in stratigraphic and petrologic studies. A rock structure can be created in any rock type or combination: * Igneous rocks are created when molten rock cools and solidifies, with or without crystallisation. They may be either plutonic bodies or volcanic extrusive. Again, erosive forces sculpt their current forms. * Metamorphic rocks are created by rocks that have been transformed into another kind of rock, usually by some combination of heat, pressure, and chemical alteration. * Sedimentary rocks are created by a variety of processes but usually involving deposition, grain by grain, layer by layer, in water or, in the case of terrestrial sediments, on land through the action of wind or sometimes moving ice. E ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Saunders_Quarry-1.jpg "Click for more on -> Sandstone")
