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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.
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Erosional unconformities at the base of the Quaternary alluvium are traced along some of the (2D) profiles.
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The dynamic evolution of the river system around this confluence has undoubtedly eroded and truncated much of the archaeological resource, but has also been ah agent of preservation, sealing sites both beneath and within fine-grained alluvium and by burying them within sands and gravels deposited by laterally migrating and/or avulsing river channels.
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These bones were extracted from sandy alluvium approximately 0.
Upon encountering unexpectedly thick alluvium ('gravel") in December 2011, the company contracted an expert in reverse circulation mud drilling to supervise the drilling of the IP target and brought in special equipment to facilitate placing casing through the gravel.
By analysing the geochemistry of groundwater from 30 boreholes throughout the Condamine Alluvium, the researchers were able to determine if there was a geochemical fingerprint that indicated there was movement between the Walloon Coal Measures (a stratified geological formation that contains coal and coal seam gas), and the Condamine Alluvium groundwater system.
The alluvium layers in this unit have a spave of 361 km2 and hard formations have a space of 331 km2.
Overlying material is unconsolidated sand and alluvium at surface with a few meters of soft weathered siltstone grading into phosphate.