Changes

==Origin==

==Origin==

New Latin, from [[Latin]], spread, bed, from neuter of ''stratus'', past participle of ''sternere'' to spread out  

New Latin, from [[Latin]], spread, bed, from neuter of ''stratus'', past participle of ''sternere'' to spread out  

*[http://en.wikipedia.org/wiki/16th_century 1599]

*[https://en.wikipedia.org/wiki/16th_century 1599]

==Definitions==

==Definitions==

*1: a bed or layer artificially made

*1: a bed or layer artificially made

*5: a statistical subpopulation

*5: a statistical subpopulation

==Description==

==Description==

In geology and related fields, a ''stratum'' (plural: '''strata''') is a layer of [http://en.wikipedia.org/wiki/Sedimentary_rock sedimentary rock] or [[soil]] with internally consistent characteristics that distinguish it from other layers. The "stratum" is the fundamental unit in a stratigraphic column and forms the basis of the study of [http://en.wikipedia.org/wiki/Stratigraphy stratigraphy].

In geology and related fields, a ''stratum'' (plural: '''strata''') is a layer of [https://en.wikipedia.org/wiki/Sedimentary_rock sedimentary rock] or [[soil]] with internally consistent characteristics that distinguish it from other layers. The "stratum" is the fundamental unit in a stratigraphic column and forms the basis of the study of [https://en.wikipedia.org/wiki/Stratigraphy stratigraphy].

When planning [http://en.wikipedia.org/wiki/Civil_engineering civil engineering] projects or other large constructions, the ''strata'' of the area where the construction takes place is a significant [[factor]] in [[design]] [[decisions]]. For example if a [http://en.wikipedia.org/wiki/Canal canal] is to be built on a route where the strata are not watertight, the canal will have to be lined with some form of waterproof material (usually [[clay]]).

When planning [https://en.wikipedia.org/wiki/Civil_engineering civil engineering] projects or other large constructions, the ''strata'' of the area where the construction takes place is a significant [[factor]] in [[design]] [[decisions]]. For example if a [https://en.wikipedia.org/wiki/Canal canal] is to be built on a route where the strata are not watertight, the canal will have to be lined with some form of waterproof material (usually [[clay]]).

Each layer is generally one of a number of [[parallel]] layers that lie one upon another, laid down by [[natural]] forces. They may extend over [http://en.wikipedia.org/wiki/1_E11_m² 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 [http://en.wikipedia.org/wiki/Cliff cliffs], road cuts, [http://en.wikipedia.org/wiki/Quarry 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 [http://en.wikipedia.org/wiki/Deposition_(sediment) deposition]: river silt, beach sand, coal swamp, sand dune, lava bed, etc.

Each layer is generally one of a number of [[parallel]] layers that lie one upon another, laid down by [[natural]] forces. They may extend over [https://en.wikipedia.org/wiki/1_E11_m² 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 [https://en.wikipedia.org/wiki/Cliff cliffs], road cuts, [https://en.wikipedia.org/wiki/Quarry 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 [https://en.wikipedia.org/wiki/Deposition_(sediment) deposition]: river silt, beach sand, coal swamp, sand dune, lava bed, etc.

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 [http://en.wikipedia.org/wiki/Burgess_Shale Burgess Shale] is a thick exposure of dark, occasionally fossiliferous, shale exposed high in the [http://en.wikipedia.org/wiki/Canadian_Rockies 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".

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 [https://en.wikipedia.org/wiki/Burgess_Shale Burgess Shale] is a thick exposure of dark, occasionally fossiliferous, shale exposed high in the [https://en.wikipedia.org/wiki/Canadian_Rockies 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".

[[Category: Earth Science]]

[[Category: Earth Science]]