391:. A bed is a single stratum that is lithologically distinguishable from other layers above and below it. In the classification hierarchy of sedimentary lithostratigraphic units, a bed is the smallest formal unit. However, only beds that are distinctive enough to be useful for stratigraphic correlation and geologic mapping are customarily given formal names and considered formal lithostratigraphic units. The volcanic equivalent of a bed, a flow, is a discrete extrusive volcanic stratum or body distinguishable by texture, composition, or other objective criteria. As in case of a bed, a flow should only be designated and named as a formal lithostratigraphic unit when it is distinctive, widespread, and useful for stratigraphic correlation. A band is a thin stratum that is distinguishable by a distinctive lithology or color and is useful in correlating strata. Finally, a key bed, also called a
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331:'s surface. Individual stratum can cover similarly large areas. Strata are typically seen as bands of different colored or differently structured material exposed in
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217:. Prior to the publication of the International Stratigraphic Guide, older publications have defined a stratum as either being either equivalent to a single
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or composed of a number of beds; as a layer greater than 1 cm in thickness and constituting a part of a bed; or a general term that includes both
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of strata. The bedding surfaces (bedding planes) that separate strata represent episodic breaks in deposition associated either with periodic
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banks. Individual bands may vary in thickness from a few millimeters to several meters or more. A band may represent a specific mode of
323:, cessation of deposition, or some combination of the two. Stacked together with other strata, individual stratum can form composite
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properties or attributes that distinguish it from adjacent layers from which it is separated by visible surfaces known as either
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Incomplete but intricately detailed: the inevitable preservation of true substrates in a time-deficient stratigraphic record.
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True substrates: the exceptional resolution and unexceptional preservation of deep time snapshots on bedding surfaces.
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In the study of rock and sediment strata, geologists have recognized a number of different types of strata, including
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Typically, a stratum is generally one of a number of parallel layers that lie one upon another to form enormous
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International stratigraphic guide: a guide to stratigraphic classification, terminology, and procedure. 2nd ed.
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275:. These strata make up much of the famous prominent rock formations in widely spaced protected areas such as
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Layer of sediment, rock or soil with internally consistent characteristics
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Outcrop of Upper
Ordovician limestone and minor shale, central Tennessee
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that can extend over hundreds of thousands of square kilometers of the
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5th ed. Alexandria, Virginia, American
Geological Institute. 779 pp.
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Neuendorf, K.K.E., Mehl, Jr., J.P., and
Jackson, J.A. , eds., 2005.
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Boulder, Colorado, The
Geological Society of America, Inc., 215 pp.
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and is recorded as being 8,800 m (29,000 ft) thick in some areas.
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Heavy minerals (dark) as thin strata in a quartz beach sand (
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International stratigraphic guide—an abridged version
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published online 22 May 2021, doi: 10.1111/sed.12900.
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marine sediments. This formation covers over half of
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71:. Unsourced material may be challenged and removed.
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283:. From top to bottom: Rounded tan domes of the
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415:Strata on a mountain face in the French Alps
291:, cliff-forming, vertically jointed, red
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131:Learn how and when to remove this message
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670:Davies, N.S., and Shillito, A.P. 2018,
654:Davies, N.S., and Shillito, A.P. 2021,
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689:Murphy, MA., and Salvador, A., 1999.
309:Glen Canyon National Recreation Area
69:adding citations to reliable sources
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469:Rainbow Basin Syncline in the
271:demonstrate the principles of
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277:Capitol Reef National Park
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307:sandstone. Picture from
281:Canyonlands National Park
203:characterized by certain
612:Salvador, A. ed., 1994.
32:Stratum (disambiguation)
533:Stratified Island near
299:, layered, lighter-red
36:Strata (disambiguation)
733:Methods in archaeology
555:Archaeological horizon
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183:and related fields, a
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267:area of southeastern
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698:, 22(4), pp.255-272.
585:Law of superposition
580:Lamination (geology)
565:Geological formation
231:. Related terms are
167:, Canada. These are
65:improve this article
30:For other uses, see
635:Glossary of Geology
475:Barstow, California
325:stratigraphic units
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301:Moenkopi Formation
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622:978-0-8137-5216-7
471:Barstow Formation
293:Wingate Sandstone
289:Kayenta Formation
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16:(Redirected from
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713:GeoWhen Database
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477:. Folded strata.
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371:Types of stratum
305:Cutler Formation
297:Chinle Formation
285:Navajo Sandstone
265:Colorado Plateau
210:bedding surfaces
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728:Stratigraphy
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63:Please help
58:verification
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452:Depot Beach
317:thicknesses
173:Nova Scotia
722:Categories
591:References
393:marker bed
367:bed, etc.
345:deposition
237:substratum
205:lithologic
147:Strata in
91:newspapers
437:Tennessee
429:limestone
361:sand dune
241:substrata
233:substrate
153:Argentina
80:"Stratum"
696:Episodes
549:See also
521:, India)
351:, beach
347:: river
337:quarries
261:Jurassic
259:through
201:sediment
121:May 2018
675:Geology
519:Chennai
399:Gallery
389:key bed
355:, coal
321:erosion
311:, Utah.
257:Permian
185:stratum
181:geology
165:Bedford
105:scholar
641:
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539:Mexico
503:Cyprus
387:, and
339:, and
333:cliffs
228:lamina
193:strata
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18:Strata
473:near
433:shale
357:swamp
341:river
329:Earth
149:Salta
112:JSTOR
98:books
639:ISBN
618:ISBN
431:and
385:band
381:flow
365:lava
353:sand
349:silt
279:and
269:Utah
255:The
239:(pl.
235:and
225:and
197:rock
84:news
34:and
377:bed
223:bed
219:bed
213:or
199:or
189:pl.
179:In
67:by
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682:^
599:^
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Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
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