alluvium


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alluvium

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

Alluvium

 

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.

REFERENCES

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.

E. V. SHANTSER

alluvium

[ə′lüv·ē·əm]
(geology)
The detrital materials that are eroded, transported, and deposited by streams; an important constituent of shelf deposits. Also known as alluvial deposit; alluvion.

alluvium

Gravel, sand, silt, soil, or other material that is deposited by running water.
References in periodicals archive ?
None of the sample satisfies all four criteria so fine grained soils (Layer-2) present in the river alluvium are not susceptible to liquefaction.
Again the coarser sediments of the Old Alluvium meander plain, Trangie Cowal, and Contemporary Macquarie pedoderms are characterised by small readings ([less than or equal to]100mS/m), while the larger readings (> 100 mS/m) coincide with the Gin Gin Hills.
This again substantiates the fact that groundwater in the Gangetic alluvium is more contaminated compared to other areas of the country.
Alluvium in Wesley Chapel Gulf provides information on the nature and effect of climatic and anthropogenic influences on the Mitchell Plain in that the fill represents a partial record of subterranean Lost River discharge and sediment load.
Testing of the alluvium showed that, unlike Sleeper, the permeability is low (less than [10.
The Bison locality is in alluvium deposited over Pliocene tholeiitic lavas of the Taos volcanic field.
A single individual occurred in the density sampling on the Alluvium.
Photo: Cavities and dry alluvium (gravel) can muffle, or decouple, an explosion that would otherwise produce much higher-magnitude seismic waves in hard rock.
Tenders are invited for Construction of Tube well in alluvium area at village- Mandali-Vihar, survey no.
The impact of geology can be appreciated from the results as it reveal that the water table is lower in the Dhok Pathan formation in comparison to the Quaternary Alluvium due to its permeable nature.
There is definitely perchlorate contamination in the Saugus alluvium aquifer.
Future studies should focus on Holocene alluvium in entrenched flood-plains and Fe-rich groundwater as the target areas for As pollution.