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302:. In older sections, there is insufficient fossil record or well preserved sections to identify the key events necessary for a GSSP, so GSSAs are defined based on fixed dates and selected criteria. The ICS first attempts to meet the standards of the GSSPs (see below) and if those fail, usually have enough information to make a preliminary selection of several competing GSSA prospects or proposals.
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useful rock layer. A worldwide multidisciplinary effort has been ongoing since 1974 to define such important metrics. The points and strata need be widespread and contain an identifiable sequence of layers or other unambiguous marker (identifiable or quantifiable) attributes.
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and improved methods of fossil dating, is used to define such boundaries. In contrast to GSSAs, GSSPs are based on important events and transitions within a particular
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is more restricted before about 539 million years ago. This is because the Earth's crust in geological time scales is constantly being recycled by
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International stratigraphic guide: A guide to stratigraphic classification, terminology, and procedure
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Gehling, James; Jensen, Sören; Droser, Mary; Myrow, Paul; Narbonne, Guy (March 2001).
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and weathering forces, and older rocks and especially readily accessible exposed
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264:(IUGS), and are used primarily for time dating of rock layers older than 630
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Geotime chart displaying geologic time periods compared to the fossil record
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454:- Deals with chronology and classifications for laymen (not GSSA/GSSPs)
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374:"Burrowing below the basal Cambrian GSSP, Fortune Head, Newfoundland"
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Chart of The Global
Boundary Stratotype Sections and Points (GSSP)
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used to define the boundaries (an internationally sanctioned
260:(ICS) under the auspices of their parent organization, the
423:. International Commission on Stratigraphy. Archived from
224:, is a chronological reference point and criterion in the
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The Global
Boundary Stratotype Section and Point (GSSP)
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List of Global
Boundary Stratotype Sections and Points
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subdivision of an age, not used by the ICS timescale
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Global
Boundary Stratotype Section and Point (GSSP)
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43:but its sources remain unclear because it lacks
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157:22 defined, tens to ~one hundred million years
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287:that can act as a time calibration are rare.
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292:Global Boundary Stratotype Section and Point
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360:, International Commission on Stratigraphy
262:International Union of Geological Sciences
142:10 defined, several hundred million years
421:"International Chronostratigraphic Chart"
74:Learn how and when to remove this message
1028:Global Standard Stratigraphic Age (GSSA)
258:International Commission on Stratigraphy
85:
354:International Chronostratigraphic Chart
343:
88:Units in geochronology and stratigraphy
172:34 defined, tens of millions of years
127:4 total, half a billion years or more
416:, New York, John Wiley and Sons, 1976
7:
232:point) between different geological
827:Adoption of the Gregorian calendar
14:
218:Global Standard Stratigraphic Age
20:
709:English and British regnal year
322:South American land mammal age
317:North American land mammal age
312:Mammal Neogene zones of Europe
187:99 defined, millions of years
1:
1325:Geologic time scales of Earth
822:Old Style and New Style dates
774:Pre-Julian / Julian
1007:Geological history of Earth
877:Astronomical year numbering
290:For more recent periods, a
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1179:Thermoluminescence dating
1074:Samarium–neodymium dating
412:Hedberg, H.D., (editor),
398:10.1017/S001675680100509X
294:(GSSP), largely based on
256:GSSAs are defined by the
893:Chinese sexagenary cycle
29:This article includes a
1107:Amino acid racemisation
250:chronostratigraphically
112:geochronological units
58:more precise citations.
1112:Archaeomagnetic dating
624:Era of Caesar (Iberia)
1012:Geological time units
300:stratigraphic section
1064:Law of superposition
1059:Isotope geochemistry
1197:Fluorine absorption
1174:Luminescence dating
1069:Luminescence dating
977:Milankovitch cycles
817:Proleptic Gregorian
649:Hindu units of time
390:2001GeoM..138..213G
378:Geological Magazine
246:geologic time scale
90:
1299:Terminus post quem
1279:Synchronoptic view
1246:Linguistic methods
1207:Obsidian hydration
1142:Radiometric dating
1127:Incremental dating
1049:Chronostratigraphy
212:sub-discipline of
100:chronostratigraphy
94:Segments of rock (
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31:list of references
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898:Geologic Calendar
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268:, lacking a good
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614:Byzantine era
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570:Calendar eras
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1345:Stratigraphy
1217:Stratigraphy
1162:Uranium–lead
1132:Lichenometry
1027:
930:Winter count
913:Mesoamerican
841:Astronomical
659:Mesoamerican
644:Sothic cycle
619:Seleucid era
604:Bosporan era
592: /
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530:Paleontology
425:the original
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381:
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296:paleontology
289:
274:
255:
221:
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210:stratigraphy
207:
70:
61:
50:Please help
42:
1157:Radiocarbon
832:Dual dating
691:Regnal year
669:Short Count
609:Bostran era
590:Anno Domini
523:Big History
503:Archaeology
64:August 2020
56:introducing
1319:Categories
752:Vietnamese
664:Long Count
599:Anno Mundi
594:Common Era
496:Key topics
489:Chronology
442:: overview
338:References
193:Chronozone
1289:Year zero
1269:Chronicle
1212:Seriation
1147:Lead–lead
1021:Standards
1002:Deep time
962:Ephemeris
848:Lunisolar
812:Gregorian
805:Gregorian
766:Calendars
729:Era names
699:Anka year
578:Human Era
508:Astronomy
406:131211543
230:benchmark
1284:Timeline
1122:Ice core
995:Concepts
742:Japanese
674:Tzolk'in
639:Egyptian
306:See also
281:tectonic
118:Eonothem
110:Notes to
1294:Floruit
1042:Methods
903:Iranian
871:Islamic
737:Chinese
548:Periods
518:History
513:Geology
448:: chart
386:Bibcode
234:periods
214:geology
208:In the
133:Erathem
52:improve
1090:dating
886:Others
852:Hebrew
747:Korean
558:Epochs
404:
285:strata
238:epochs
163:Series
153:Period
148:System
96:strata
923:Aztec
867:Lunar
862:Solar
856:Hindu
719:Limmu
679:Haab'
634:Hijri
402:S2CID
358:(PDF)
248:in a
198:Chron
178:Stage
168:Epoch
98:) in
37:, or
918:Maya
653:Yuga
553:Eras
535:Time
275:The
242:ages
222:GSSA
216:, a
394:doi
382:138
272:.
240:or
183:Age
138:Era
123:Eon
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