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stratum

 
Dictionary: stra·tum   (strā'təm, străt'əm) pronunciation
 
n., pl. -ta (-tə) or -tums.
  1. A horizontal layer of material, especially one of several parallel layers arranged one on top of another.
  2. Geology. A bed or layer of sedimentary rock having approximately the same composition throughout.
  3. Any of the regions of the atmosphere, such as the troposphere, that occur as layers.
  4. Biology. A layer of tissue: the epithelial stratum.
  5. A level of society composed of people with similar social, cultural, or economic status.
  6. One of a number of layers, levels, or divisions in an organized system: a complex poem with many strata of meaning.

[Latin strātum, a covering, from neuter past participle of sternere, to spread. See stratus.]

stratal stra'tal (strāt'l) adj.

USAGE NOTE   The standard singular form is stratum; the standard plural is strata (or sometimes stratums), not stratas.


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Dental Dictionary: stratum
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n.pl

(n.pl strata) a layer of the epidermis or the epithelium of the oral mucosa.

 
Geography Dictionary: stratum
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strata (pl.)

In geology, a layer of distinctive deposits with surfaces roughly parallel to those above and below.

 
Architecture: stratum
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A bed of sedimentary rock or earth.


 

[De]

A single deposit or cultural level.

 

Pl. strata [L.] a sheetlike mass of tissue of fairly uniform thickness; distinct layers making up various tissues or organs, as of the skin, brain, retina.

  • s. avasculosum — the avascular stratum in the margin of the iris.
  • s. basale — the mitotically active, basal layer of the epidermis, consisting of columnar to cuboidal keratinocytes on a basement membrane.
  • s. corneum — the outer horny layer of the epidermis, consisting of cells that are non-nucleated, keratinized and desquamating.
  • s. germinativum — in the epidermis, located between the stratum basale and the stratum granulosum. Together with the basal layer, called the malpighian layer. Called also germinative layer.
  • s. granulosum — 1. the layer of cells between the stratum lucidum and the stratum spinosum of the skin, very thin and not always present. Called also the granular layer.
  • — 2. the deep layer of the cortex of the cerebellum. — 3. the layer of follicle cells lining the theca of the vesicular ovarian follicle. Called also granular layer.
  • s. lamellatum — laminae of the hoof corium.
  • s. lucidum — the translucent layer of the skin just beneath the stratum corneum. Called also clear layer. Present in the epidermis of the planum nasale of several species and footpads of carnivores.
  • s. spinosum — the layer of the epidermis between the stratum granulosum and the stratum basale, marked by the presence of prickle cells; called also spinous layer and prickle-cell layer.
  • s. tectorium — the layer of horny scales claimed to exist on the surface of the horse's hoof that gives it the smooth glossy appearance.
 
Wikipedia: Stratum
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Goldenville strata in a quarry in 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.

In geology and related fields, a stratum (plural: strata) is a layer of rock or soil with internally consistent characteristics that distinguishes it from contiguous layers. 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 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.

Geologists study rock strata and categorize them by the material in the beds. Each distinct layer is usually assigned to a "formation" name 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." Groups may be collected into "supergroups."

The stratum is the fundamental unit in a stratigraphic column and forms the basis of the study of stratigraphy.

When planning 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 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).

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Translations: Stratum
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Dansk (Danish)
n. - lag

Nederlands (Dutch)
laag

Français (French)
n. - (Géol) strate, (Biol) couche, couche (sociale)

Deutsch (German)
n. - Schicht, Stratum

Ελληνική (Greek)
n. - στρώμα, διάστρωση, (γεωλ.) πέτρωμα

Italiano (Italian)
strato, falda

Português (Portuguese)
n. - camada (f)

Русский (Russian)
пласт, слой, уровень, страта

Español (Spanish)
n. - capa, estrato

Svenska (Swedish)
n. - skikt, lager, stratum

中文(简体)(Chinese (Simplified))
层, 组织层, 地层, 社会阶层

中文(繁體)(Chinese (Traditional))
n. - 層, 組織層, 地層, 社會階層

한국어 (Korean)
n. - 지층, (조직의) 층, 계층

日本語 (Japanese)
n. - 岩層, 地層, 階層

العربيه (Arabic)
‏(الاسم) طبقه (صخور), طور (تاريخ أو نمو)‏

עברית (Hebrew)
n. - ‮שכבה, רובד, מעמד חברתי‬


 
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Dictionary. The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2007. Published by Houghton Mifflin Company. All rights reserved.  Read more
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Architecture. McGraw-Hill Dictionary of Architecture and Construction. Copyright © 2003 by McGraw-Hill Companies, Inc. All rights reserved.  Read more
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