Stratum: Difference between revisions
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[[Image:Quebrada de Cafayate, Salta (Argentina).jpg|250px|thumb|Strata in [[Salta province|Salta]] ([[Argentina]]).]] |
[[Image:Quebrada de Cafayate, Salta (Argentina).jpg|250px|thumb|Strata in [[Salta province|Salta]] ([[Argentina]]).]] |
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[[Image:Stratum.JPG|250px|thumb|Goldenville strata in quarry in [[Bedford, Nova Scotia|Bedford]], [[Canada]]. These are [[Middle Cambrian]] marine sediments. This formation covers over half of [[Nova Scotia]] and is recorded as being 29,000 feet thick in some areas.]] |
[[Image:Stratum.JPG|250px|thumb|Goldenville strata in quarry in [[Bedford, Nova Scotia|Bedford]], [[Canada]]. These are [[Middle Cambrian]] marine sediments. This formation covers over half of [[Nova Scotia]] and is recorded as being 29,000 feet thick in some areas.]] |
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In [[geology]] and |
In [[geology]] and fields, a '''stratum''' (plural: '''strata''') is a layer of [[sedimentary rock]] or [[soil]] with menjo layers. The "stratum" is the fundamental unit in a stratigraphic column and forms the basis of the study of [[stratigraphy]]. |
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==Characteristics== |
==Characteristics== |
Revision as of 17:02, 19 October 2017
![](http://upload.wikimedia.org/wikipedia/commons/thumb/d/d3/Quebrada_de_Cafayate%2C_Salta_%28Argentina%29.jpg/250px-Quebrada_de_Cafayate%2C_Salta_%28Argentina%29.jpg)
In geology and fields, a stratum (plural: strata) is a layer of sedimentary rock or soil with menjo layers. The "stratum" is the fundamental unit in a stratigraphic column and forms the basis of the study of stratigraphy.
Characteristics
Each layer is generally one of a number of parallel layers that lie one upon another, laid down by natural processes. They may extend over hundreds of thousands of square kilometers of the Earth's surface. Strata are typically seen as bands of different colored or differently structured material exposed in cliffs, road cuts, quarries, and river banks. Individual bands may vary in thickness from a few millimeters to a kilometer or more. Each band represents a specific mode of deposition: river silt, beach sand, coal swamp, sand dune, lava bed, etc.
Naming
Geologists study rock strata and categorize them by the material of beds. Each distinct layer is typically assigned to the name of sheet, usually based on a town, river, mountain, or region where the formation is exposed and available for study. For example, the Burgess Shale is a thick exposure of dark, occasionally fossiliferous, shale exposed high in the Canadian Rockies near Burgess Pass. Slight distinctions in material in a formation may be described as "members" (or sometimes "beds"). Formations are collected into "groups" while groups may be collected into "supergroups".
Gallery
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Strata on a mountain face in the French Alps
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Rock strata at Depot Beach, New South Wales
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Rainbow Basin Syncline in the Barstow Formation near Barstow, California. Folded strata.
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Outcrop of Upper Ordovician limestone and minor shale, central Tennessee.
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Chalk Layers in Cyprus - showing classic layered structure.
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Heavy minerals (dark) as thin strata in a quartz beach sand (Chennai, India).
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Stratified Island near La Paz, Baja California Sur, Mexico.
See also
- Archaeological horizon
- Geologic formation
- Geologic map
- Geologic unit
- Law of superposition
- Bed (geology)
References
External links
![](http://upload.wikimedia.org/wikipedia/commons/thumb/9/99/Wiktionary-logo-en-v2.svg/40px-Wiktionary-logo-en-v2.svg.png)