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a fine-grained fertile soil consisting of mud, silt, and sand deposited by flowing water on flood plains, in river beds, and in estuaries



or alluvial deposits. (1) Deposits of fluvial water courses—rivers, streams—forming floodplains and terraces of river valleys. They play a very important role in the structure of most continental sedimentary formations. The alluvium of plains rivers (see Figure 1) usually combines fluvial alluvium deposited in the migrating bed (obliquely laminated sands and gravel), floodplain alluvium which accumulates on the fluvial during floods (mainly loams and sandy loams), and oxbow-lake alluvium which settles in the oxbow-lakes (mainly sandy loams and loams which are rich in organic matter).

Figure 1. Diagram of structure of alluvium from plain river: (1) fluvial alluvium, (2) floodplain alluvium, (3) oxbow-lake alluvium, (4) bedrock from slopes and bottom of river valley, (5) water level during flooding.

The composition and structure of the alluvium differ substantially depending on the size and hydraulic regime of the flow, the relief of the drainage system, and the rock composing it. For example, in the alluvium of mountain rivers, there is a predominance of boulder and pebble fluvial alluvium; streams which flow through ravines and gullies deposit poorly graded alluvium in which it is difficult to distinguish the fluvial, floodplain, and other types of alluvium. In ancient sedimentary beds, the alluvium is usually cemented together and composed of hard fragmented rock such as conglomerates, sandstones, argillites, and so forth. The fluvial alluvium may contain placers of gold, platinum, and other useful minerals in addition to deposits of construction sands and gravel.

(2) In foreign literature, alluvium is the name often given to any deposits of running waters, including proluvium and deluvium.

(3) The obsolete name of all recent continental deposits formed in the postglacial age (Holocene); the term “alluvium” is sometimes used in this sense only in German literature.


Shantser, E. V. Alluvii ravninnykh rek umerennogo poiasa i ego znachenie dlia poznaniia zakonomernostei stroeniia i for-mirovaniia alliuvial’nykh svit. Moscow, 1951.
Shantser, E. V. Ocherki ucheniia o geneticheskikh tipakh. kontinental’nykh osadochnykh obrazovanii. Moscow, 1966.



The detrital materials that are eroded, transported, and deposited by streams; an important constituent of shelf deposits. Also known as alluvial deposit; alluvion.


Gravel, sand, silt, soil, or other material that is deposited by running water.
References in periodicals archive ?
Design, manufacture and supply of small vessel for monitoring the implementation of conditions issued under the water act permits for use of water subject to seizure of alluvial deposits in the bulgarian section of the danube river from the mouth of timok (km 845.
The most economically important alluvial deposits (terraces) are Holocene in age, with the modern-day meandering Mbuji-Mayi river system cutting down into the valley floor of the Mbuji-Mayi Formation.
Located southwest of Kumasi, in Ghana's Ashanti Region, the Nyinahin Concession might host both vein deposits in the meta-sedimentary rocks of Ghana's Precambrian shield, and also host alluvial deposits in the sediments of Pleistocene to Recent age of the Ofin River Valley.
Its major focus and expertise is centered on the commercialization of small-scale mines and alluvial deposits.
F) announces that after an intensive search, the Company has hired Tanzanian Mineral Exploration (TANZMINEX), a geological consulting firm based in Arusha, Tanzania, specializing in alluvial deposits.
In the meantime, we are exploring the Million Mountain trend to evaluate the grade and extent of the alluvial deposits recently discovered in nine zones.
These local miners are already active and recovering diamonds from surface alluvial deposits on the western boundary of our Magembe property.
Pacific Gold Corp, (OTCBB: PCFG), announced today that it has signed a lease agreement that will allow the Company to mine the alluvial deposits on fee simple land adjacent to the Company's 29 placer gold mining claims near Crescent Valley, Nevada.
Pan samples of alluvial deposits at Dime Creek revealed high-grade placer gold and platinum concentrations, as well, as uranium at the head of Quartz Creek.
The capital and operating costs of extraction for alluvial deposits is typically less than those costs associated with hard-rock deposits.
The alluvial deposits on Dime Creek are composed of mostly volcanic andesite and basalt sand and gravel with occasional cobbles of intrusive olivine dunite.