Alluvium

Alluvium (from the Latin alluvius, from alluere, "to wash against") is loose, unconsolidated (not cemented together into a solid rock) soil or sediment that has been eroded, reshaped by water in some form, and redeposited in a non-marine setting.[1][2] Alluvium is typically made up of a variety of materials, including fine particles of silt and clay and larger particles of sand and gravel. When this loose alluvial material is deposited or cemented into a lithological unit, or lithified, it is called an alluvial deposit.[3]

Alluvial Gravels at the Blue Ribbon Mine Alaska
Section of alluvium at the Blue Ribbon Mine in Alaska
South Africa-Eastern Cape-Gamtoos Valley-Alluvial Gravel01
Alluvium deposits in the Gamtoos Valley in South Africa
Amazon alluvium deposit - autazes
Alluvial river deposits in the Amazon Basin, near Autazes, AM, Brazil. The seasonal deposits are extremely fertile, and crucial to subsistence farming in the Amazon Basin along the river banks.

Definitions

The term "alluvium" is not typically used in situations where the formation of the sediment can clearly be attributed to another geologic process that is well described. This includes (but is not limited to): lake sediments (lacustrine), river sediments (fluvial), or glacially-derived sediments (glacial till). Sediments that are formed or deposited in a perennial stream or river are typically not referred to as alluvial.[3]

Age

Most alluvium is geologically Quaternary in age, and is often referred to as "cover" because these sediments obscure the underlying bedrock. Most sedimentary material that fills a basin ("basin fill") that is not lithified is typically lumped together as "alluvial".[3] Alluvium of Pliocene age occurs, for example, in parts of Idaho.[4] Alluvium of late Miocene age occurs, for example, in the valley of the San Joaquin River, California.[5]

Ores

Alluvium can contain valuable ores such as gold and platinum and a wide variety of gemstones. Such a concentration of valuable ores is termed a placer deposit.[3]

See also

References

  1. ^ Glossary of Geological Terms. Geotech.org. Retrieved on 2012-02-12.
  2. ^ Geology Dictionary – Alluvial, Aquiclude, Arkose. Geology.Com. Retrieved on 2012-02-12.
  3. ^ a b c d Chisholm, 1911
  4. ^ Ames, Dan (1998), "Formation of the Soils" (PDF), Soil Survey of Jerome County and Part of Twin Falls County, Idaho, Natural Resources Conservation Service, USDA, p. 238
  5. ^ Huber, N. King (1981). Amount and Timing of Late Cenozoic Uplift and Tilt of the Central Sierra Nevada, California—Evidence from the Upper San Joaquin River Basin (USGS Professional Paper 1197) (PDF). Washington D.C.: USGS. p. 13.

External links

Barind Tract

Barind Tract (alternately called the Varendra Tract in English and Borendro Bhumi in Bengali) is the largest Pleistocene era pysiographic unit in the Bengal Basin. It covers most of Dinajpur, Rangpur, Pabna, Rajshahi, Bogra, and Joypurhat districts of Rajshahi Division and Rangpur Division in Bangladesh as well as entirety of Uttar Dinajpur, Dakshin Dinajpur and most of Maldah districts in West Bengal, India. It is made up of several separate sections in the northwestern part of Bangladesh, and, northern part of West Bengal, India covering a total area of approximately 10000 km² of mostly old alluvium. On the eastern edge of the tract is a lower fault escarpment. Through the fault troughs run the little Jamuna, Atrai and Lower Punarbhaba rivers. To the west, the main area is tilted up, and to the east this area is tilted downwards. The climate of the tract differs from that of much of India, in that more extreme temperature variations (ranging from 45 degrees Celsius down to five degrees Celsius) are encountered there. It is divided into three units: The Recent Alluvial Fan, the Barind Pleistocene, and the Recent Floodplain. These are divided by long, narrow bands of recent alluvium.

Colluvium

Colluvium (also colluvial material or colluvial soil) is a general name for loose, unconsolidated sediments that have been deposited at the base of hillslopes by either rainwash, sheetwash, slow continuous downslope creep, or a variable combination of these processes. Colluvium is typically composed of a heterogeneous range of rock types and sediments ranging from silt to rock fragments of various sizes. This term is also used to specifically refer to sediment deposited at the base of a hillslope by unconcentrated surface runoff or sheet erosion.

Coongan River

The Coongan River is an ephemeral river in the Pilbara region of Western Australia.

The headwaters of the river rise below the Chichester Range. The river flows in a northerly direction past Marble Bar then through the Gorge Range before discharging into the De Grey River, of which it is a tributary, at Mulyie Pool near Mount Woodhouse.

The town of Marble Bar also draws approximately 180ML scheme water from the river's alluvium per year.

The river has eight tributaries including; Talga River, Triberton Creek, Emu Creek and Budjan Creek.

The name is Indigenous Australian in origin, and was first recorded in 1878 by Alexander Forrest. The traditional owners of the area are the Njamal or Nyamal peoples.The rivers water quality varies dependent of the flow but the average turbidity of the river water is 587 NTU and the average salinity is 100 mg/L.

Diluvium

Historically, diluvium was a term in geology for superficial deposits formed by flood-like operations of water, and so contrasted with alluvium or alluvial deposits formed by slow and steady aqueous agencies. The term was formerly given to the boulder clay deposits, supposed to have been caused by the Noachian deluge.

In the late 20th century Russian geologist Alexei Rudoy proposed the term "diluvium" for description of deposits created as a result of catastrophic outbursts of Pleistocene giant glacier-dammed lakes in intermontane basins of the Altai. The largest of these lakes, Chuya and Kuray, had volumes of water in hundreds of cubic kilometers, and their discharge in peak hydrograph flow rate exceeded the maximum rates of the well-known Pleistocene Lake Missoula floods in North America. The term "diluvium" in the meaning of A. N. Rudoy has become accepted, and the process of diluvial morpholithogenesis can be found in modern textbooks.

Fluvial terrace

Fluvial terraces are elongated terraces that flank the sides of floodplains and fluvial valleys all over the world. They consist of a relatively level strip of land, called a “tread,” separated from either an adjacent floodplain, other fluvial terraces, or uplands by distinctly steeper strips of land called “risers.” These terraces lie parallel to and above the river channel and its floodplain. Because of the manner in which they form, fluvial terraces are underlain by fluvial sediments of highly variable thickness.Fluvial terraces are the remnants of earlier floodplains that existed at a time when either a stream or river was flowing at a higher elevation before its channel downcut to create a new floodplain at a lower elevation. Changes in elevation can be due to changes in the base level (elevation of the lowest point in the fluvial system, usually the drainage basin) of the fluvial system, which leads to headward erosion along the length of either a stream or river, gradually lowering its elevation. For example, downcutting by a river can lead to increased velocity of a tributary, causing that tributary to erode toward its headwaters. Terraces can also be left behind when the volume of the fluvial flow declines due to changes in climate, typical of areas which were covered by ice during periods of glaciation, and their adjacent drainage basins.

Geology of India

The geology of India is diverse. Different regions of India contain rocks belonging to different geologic periods, dating as far back as the Eoarchean Era. Some of the rocks are very deformed and altered. Other deposits include recently deposited alluvium that has yet to undergo diagenesis. Mineral deposits of great variety are found in the Indian subcontinent in huge quantity. Even India's fossil record is impressive in which stromatolites, invertebrates, vertebrates and plant fossils are included.

India's geographical land area can be classified into the Deccan Traps, Gondwana and Vindhyan.

The Deccan Traps covers almost all of Maharashtra, a part of Gujarat, Karnataka, Madhya Pradesh and Andhra Pradesh marginally. During its journey northward after breaking off from the rest of Gondwana, the Indian Plate passed over a geologic hotspot, the Réunion hotspot, which caused extensive melting underneath the Indian Craton. The melting broke through the surface of the craton in a massive flood basalt event, creating the Deccan Traps. It is also thought that the Reunion hotspot caused the separation of Madagascar and India.

The Gondwana and Vindhyan include within its fold parts of Madhya Pradesh, Chhattisgarh, Odisha, Bihar, Jharkhand, West Bengal, Andhra Pradesh, Maharashtra, Jammu and Kashmir, Punjab, Himachal Pradesh, Rajasthan and Uttarakhand.

The Gondwana sediments forms a unique sequence of fluviatile rocks deposited in Permo-Carboniferous time. The Damodar and Sone river valleys and Rajmahal hills in the eastern India contain a record of the Gondwana rocks.

Geology of Israel

The geology of Israel includes igneous and metamorphic crystalline basement rocks from the Precambrian overlain by a lengthy sequence of sedimentary rocks extending up to the Pleistocene and overlain with alluvium, sand dunes and playa deposits.

Hann River (Queensland)

The Hann River is a river in Far North Queensland, Australia.

The headwaters of the river rise in the Great Dividing Range on Cape York Peninsula northeast of the settlement of Kimba. The river flows in a north easterly direction, joined by four minor tributaries, crosses the Peninsula Developmental Road and then enters the Lakefield National Park where it forms a series of braided channels then re-forms to a single channel and discharges into the North Kennedy River northwest of Lakefield. The river descends 167 metres (548 ft) over its 140-kilometre (87 mi) course.The river has a catchment area of 9,557 square kilometres (3,690 sq mi) of which an area of 227 square kilometres (88 sq mi) is composed of estuarine wetlands.The floodplain is composed of reddish grey sand loam produced from the underlying sand material of Cainozoic age. The underlying geology is predominantly alluvium of Quaternary age with areas of older rock made up of sandstone of Middle Jurassic age in the Bathurst Range and the granite of Late Silurian age in the Great Dividing Range of the upper catchment. Fringing vegetation is made up of Stringybark, Bloodwood, Moreton Bay Ash and Ironbark trees with a ground cover of coarse grasses such as speargrass.The river was named after the explorer and pastoralist William Hann who explored the area in 1872. It was named by the prospector James Venture Mulligan in 1875.

Indo-Gangetic Plain

The Indo-Gangetic Plain, also known as the Indus-Ganga Plain and the North Indian River Plain, is a 630-million-acre (2.5-million km2) fertile plain encompassing Northern regions of the Indian subcontinent, including most of northern and eastern India, the eastern parts of Pakistan, virtually all of Bangladesh and southern plains of Nepal. The region is named after the Indus and the Ganges rivers and encompasses a number of large urban areas. The plain is bound on the north by the Himalayas, which feed its numerous rivers and are the source of the fertile alluvium deposited across the region by the two river systems. The southern edge of the plain is marked by the Chota Nagpur Plateau. On the west rises the Iranian Plateau.

Little Wapwallopen Creek

Little Wapwallopen Creek is a tributary of the Susquehanna River in Luzerne County, Pennsylvania, in the United States. It is approximately 17 miles (27 km) long and flows through Rice Township, Dorrance Township, Conyngham Township, and Hollenback Township. The watershed of the creek has an area of 39.5 square miles (102 km2). The creek is designated as a Coldwater Fishery and a Migratory Fishery and is not considered to be impaired. It has two named tributaries: Pond Creek and Nuangola Outlet. Wild trout naturally reproduce in the creek.

Little Wapwallopen Creek ranges from slightly acidic to slightly basic. It is a significant source of flooding in Conyngham Township, Dorrance Township, and Rice Township. Numerous bridges have been constructed across the creek. The surficial geology in its vicinity consists of alluvium, alluvial terrace, alluvial fan, Wisconsinan Ice-Contact Stratified Drift, Wisconsinan Till, and wetlands. Numerous bridges have also been constructed across the creek.

Lourensford Alluvium Fynbos

Lourensford Alluvium Fynbos is a critically endangered vegetation type that is endemic to Cape Town. Though closest to Fynbos, it has characteristics of both Fynbos and Renosterveld vegetation and is thus actually a unique hybrid vegetation type.

Muthapudupet

Muthapudupet is a city near to Chennai in the Chennai district and comes under Chennai Metropolitan area Muthapudupet is around 8 kilometers from Avadi.

Areas around Muthapudupet were once paddy fields, fruit farms, lakes, swamps and forests. Now the field areas have shrunk and residential plots have sprung up. Highest Natural point is 60 m above Mean Sea level. The soil is sandy and instantial laterite, mostly Recent Alluvium. Geological formations are concealed by Recent alluvium, with little or no exposure of rocks, most formations being Archean and tertiary sediments. Alluvial deposits of thickness of 28 meters, can amplify ground shaking during Tremors.

Muthapudupet is a predominantly Tamil speaking area with sizable Telugu speakers. Most people here are Multilingual, Speaking Tamil, Mothertongue and Hindi/English. One can find people from every region of India in Muthapudupet-Mittanamallee. Thanks to nearby Defence/Central Government Establishments. Central Government is the largest employer in Muthapudupet.

A new Tidel park will be coming up at near Muthapudupet (Pattabiram, Avadi) in MTH road. So many people of the nearby areas will get job opportunity. The land value of Muthapudupet, Palavedu, Pattabiram, Avadi and some nearby areas will increase fastly due to coming up of Tidel park (IT park information technology).

Nine Partners Creek

Nine Partners Creek (also known as Leslie Creek) is a tributary of Tunkhannock Creek in Susquehanna County, Pennsylvania, in the United States. It is approximately 10 miles (16 km) long and flows through New Milford Township, Harford Township, and Lenox Township. The watershed of the creek has an area of 38.6 square miles (100 km2). The creek has two named tributaries: Butler Creek and Leslie Creek. The surficial geology in the vicinity of Nine Partners Creek includes Wisconsinan Till, alluvium, bedrock, alluvial fan, and wetlands. The creek's drainage basin is designated as a Coldwater Fishery and a Migratory Fishery.

Outlet Creek

Outlet Creek is an Eel River tributary draining the Little Lake Valley northerly through a canyon of the California Coast Ranges. The Northwestern Pacific Railroad bridges the creek twelve times, following it through the canyon. California State Route 162 bridges the creek once, following the canyon closely downstream of Longvale, California, and U.S. Route 101 bridges the creek twice, paralleling it less closely upstream of Longvale. After leaving Quaternary alluvium of the Little Lake Valley, the canyon exposes undivided Cretaceous marine sedimentary and metasedimentary rocks upstream of Longvale and Franciscan Assemblage downstream of Longvale. Outlet Creek provides groundwater recharge, recreation, and agricultural and industrial water supply plus wildlife habitat including cold freshwater habitat for fish migration and spawning.

Paleosol

In the geosciences, paleosol (palaeosol in Great Britain and Australia) can have two meanings. The first meaning, common in geology and paleontology, refers to a former soil preserved by burial underneath either sediments (alluvium or loess) or volcanic deposits (volcanic ash), which in the case of older deposits have lithified into rock. In Quaternary geology, sedimentology, paleoclimatology, and geology in general, it is the typical and accepted practice to use the term "paleosol" to designate such "fossil soils" found buried within either sedimentary or volcanic deposits exposed in all continents as illustrated by Rettallack (2001), Kraus (1999), and other published papers and books.

In soil science, paleosols are soils formed long periods ago that have no relationship in their chemical and physical characteristics to the present-day climate or vegetation.

Such soils form on extremely old continental cratons and as small scattered localities in outliers of ancient rock.

Panguipulli Formation

Panguipulli Formation (Spanish: Formación Panguipulli) is a sedimentary formation of Triassic age located in Los Ríos Region and southernmost Araucanía Region in south–central Chile. The formation is variously covered by Quaternary lavas in the east and Quaternary morraines, Holocene alluvium and colluvium in the west. The formation and make up possibly the remnants of an ancient lake and river system. The formation is named after the town of Panguipulli on the western edge of Panguipulli Lake. The formation has evidence of low grade metamorphism and is locally intruded by plutons of the North Patagonian Batholith that are of Jurassic, Cretaceous and Miocene age.

Placer deposit

In geology, a placer deposit or placer is an accumulation of valuable minerals formed by gravity separation from a specific source rock during sedimentary processes. The name is from the Spanish word placer, meaning "alluvial sand". Placer mining is an important source of gold, and was the main technique used in the early years of many gold rushes, including the California Gold Rush. Types of placer deposits include alluvium, eluvium, beach placers, and paleoplacers.

Placer materials must be both dense and resistant to weathering processes. To accumulate in placers, mineral particles must be significantly denser than quartz (whose specific gravity is 2.65), as quartz is usually the largest component of sand or gravel. Placer environments typically contain black sand, a conspicuous shiny black mixture of iron oxides, mostly magnetite with variable amounts of ilmenite and hematite. Valuable mineral components often occurring with black sands are monazite, rutile, zircon, chromite, wolframite, and cassiterite.

River Axe (Lyme Bay)

The River Axe is a river in Dorset, Somerset and Devon, in the south-west of England.

It rises near Beaminster in Dorset, flows west then south by Axminster and joins the English Channel at Axmouth near Seaton in Lyme Bay. During its 22-mile (35 km) course it is fed by various streams and by the tributary rivers Yarty and Coly.

It is a shallow, non-navigable river, although its mouth at Axmouth has some boating activity.The name derives from a Common Brittonic word meaning "abounding in fish", which is also the root for the River Axe in the Bristol Channel as well as the Exe, Esk, Usk and other variants. The name is cognate with pysg (plural of pysgod), the Welsh word for fish.In 1999, a section of the river extending for 13 kilometres (8.1 mi)—from the confluence with the Blackwater River (ST325023) to Colyford Bridge (SY259927)—was designated a Site of Special Scientific Interest (SSSI). It was described as supporting "an exceptionally diverse aquatic and marginal flora". The river's diversity comes from its active geomorphology, which has created a number of natural features that support niche ecologies; it also comes from there being a limited number of trees on the river bank, allowing in light; and also the riverbed stability in the lower reaches of the river. A majority of the SSSI runs through Devon; only 150 metres runs through Dorset. The underlying geology of the riverbed is alluvium with areas of valley gravel, clay, shale and marl. The fish life in the river is considered of European interest; aquatic life more generally includes salmon, bullheads, otters, medicinal leeches and kingfishers; all are of particular value, as is the diverse aquatic and marginal plant life. The geomorphology of the meanders south of Axminster are the particular geological interest.

Spessartine

Spessartine, sometimes mistakenly referred to as spessartite, is a nesosilicate, manganese aluminium garnet species, Mn2+3Al2(SiO4)3. The mineral spessartine should not be confused with a type of igneous rock (a lamprophyre) called spessartite.

Spessartine's name is a derivative of Spessart in Bavaria, Germany, the type locality of the mineral. It occurs most often in granite pegmatite and allied rock types and in certain low-grade metamorphic phyllites. Sources include Australia, Myanmar, India, Afghanistan, Israel, Madagascar, Namibia, Nigeria, Mozambique, Tanzania and the United States. Spessartine of an orange-yellow has been called Mandarin garnet and is found in Madagascar. Violet-red spessartines are found in rhyolites in Colorado and Maine. In Madagascar, spessartines are exploited either in their bedrock or in alluvium. The orange garnets result from sodium-rich pegmatites. Spessartines are found in bedrock in the highlands in the Sahatany valley. Those in alluvium are generally found in southern Madagascar or in the Maevatanana region.Spessartine forms a solid solution series with the garnet species almandine. Well-formed crystals from this series, varying in color from very dark-red to bright yellow-orange, were found in Latinka, Rhodope Mountains, Kardzhali Province, Bulgaria. Spessartine, like the other garnets, always occurs as a blend with other species. Gems with high spessartine content tend toward a light orange hue, while almandine prevalence induces red or brownish hues.

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