Global Boundary Stratotype Section and Points

Global Boundary Stratotype Sections and Points (GSSPs) are reference points on stratigraphic sections of rock which define the lower boundaries of stages on the International Chronostratigraphic Chart. The boundary is defined by a spike in a rock succession coincident with available biological and other markers. Since 1977, the ICS has maintained the international GSSP register.

Locations

GSSPs are spread throughout the world. The map below indicates each's approximate location.

Click on the [ ] icon for full-screen map

Workflow and protocol for GSSP proposals

Candidate GSSPs [and likewise GSSAs] are evaluated by the ICS and its constituent

Candidate GSSPs [and likewise GSSAs] are evaluated by the ICS and its constituent subcommissions and working groups based on a long list of criteria (Hedberg, 1976; Cowie et al., 1986; Salvador, 1994; Remané et al., 1996; Harper et al., 2023). This is reflected in the attached proforma or standard document that will be utilized for all outstanding GSSPs and GSSAs (produced by Angela Coe, Elisabetta Erba and Charles Henderson).

The most important criteria is that the boundary at the candidate stratotype is defined at the level in rock coincident with 'a single stratigraphic signal within an interval of multiple, varied stratigraphic signals', that should allow for reliable, high-resolution correlation across the greatest possible paleogeographical range of paleoenvironmental settings (Finney, 2013).

Identification and field investigations of candidate stratotype sections and boundary intervals, and drafting of proposals, are carried out by subcommissions of ICS (stratigraphy.org/subcommissions) and usually by smaller boundary-working groups. One or more candidate GSSP proposals [and/or GSSA proposals] may be considered for approval by the voting members (ca. 20; voting member tenured for a maximum of 12 years) of a subcommission, and a single proposal that receives a supermajority vote (>60% of the voting membership) is considered approved. One consequence of this approach is that disagreement can arise, because type sections that are favoured for historical reasons may be abandoned, previously established boundary levels may be greatly changed, and in some instances historical units (and their names) are replaced by new and different ones (retiring old names).

Once accepted by a subcommission, a proposal is then forwarded to the ICS for consideration and approval. The ICS voting members are the executive officers of ICS and the chairs of the 17 ICS subcommissions, each of whom has a single vote. They evaluate and discuss each proposal, then vote. If the proposal is approved by supermajority votes, the proposal is forwarded to the IUGS Executive Committee. Once it is also approved by majority within the IUGS Executive Committee, the proposal is formally ratified and recognised as an international geostandard. The ICS executive updates the International Chronostratigraphic Chart and the GSSP table on stratigraphy.org (typically within days).

A manuscript documenting the ratified GSSP proposal is submitted for publication, generally in the IUGS's journal Episodes (episodes.org). At the GSSP stratotype locality, a physical marker should be placed, that may be officially launched in a public dedication ceremony (typically 1-3 year after ratification). A proposal to change a newly established unit and/or GSSP cannot be made within the first 10 years after its ratification, a clause to ensure the stability of the global chronostratigraphic framework.

Cowie, J.W., Ziegler, W., Boucot, A.J., Bassett, M.G., and Remané, J., 1986, Guidelines and Statutes of the International Commission on Stratigraphy (ICS). Courier Forschungsinstitut Senckenberg, v. 83, pp. 1-14.

Finney, S.C., 2013, The Reality of GSSPs. Ciências da Terra, v. 18, pp. 9-12.

Harper, D.A.T., Bown, P., and Coe, A., 2022, Chronostratigraphy: understanding rocks and time. In: Coe, A.L., ed., Deciphering Earth's History: the Practice of Stratigraphy. Geological Society, London, pp. 227-243.

Hedberg, H.D., ed, 1976, International Stratigraphic Guide - A Guide to Stratigraphic Classification, Terminology, and Procedure. New York, John Wiley & Sons, 200 p.

Remané, J., Bassett, M.G., Cowie, J.W., Gohrbandt, K.H., Lane, H.R., Michelsen, O., and Wang, N., 1996, Revised guidelines for the establishment of global chronostratigraphic standards by the International Commission on Stratigraphy (ICS). Episodes, v. 19, pp. 77-81. https://doi.org/10.18814/epiiugs/1996/v19i3/007

Salvador, A., ed, 1994, International Stratigraphic Guide - A Guide to Stratigraphic Classification, Terminology, and Procedure, Second Edition. Boulder, Colorado, The International Union of Geological Sciences and The Geological Society of America, 214 p.

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Rules for chronostratigraphic boundary-definition proposals

A geologic section has to fulfill a set of criteria to be adapted as a GSSP by the

A geologic section has to fulfill a set of criteria to be adapted as a GSSP by the ICS. The following list summarizes the criteria where the imperative words SHOULD and MUST are defined according to RCF2119:

  1. A GSSP section MUST contain a stratigraphic marker that recognizes the lower boundary of a geologic Stage
  2. The boundary MUST be recognized by an observable, unambiguous change in the physical properties or fossil content of the strata, for example the first appearance datum of a fossil species
    • There SHOULD be other physical manifestations (secondary markers) that can be used to locate the boundary, e.g. other fossils, chemical changes, geomagnetic reversal
    • The section in which the marker appears SHOULD have layers containing minerals that can be radiometrically dated to assign ages to the depositional events at or bracketing the boundary horizon
    • The primary or secondary marker events MUST be manifested in regional and global stratigraphic sections to allow correlation in outcrops of the same age
    • The markers should be independent of facies
  3. The outcropping stratigraphic section containing the GSSP marker MUST have adequate thickness to support global correlation
  4. Sedimentation in the section containing the boundary must MUST be continuous without any changes in facies
  5. The section containing the marker SHOULD be unaffected by tectonic and sedimentary movements, and metamorphism
  6. The section containing the marker must MUST be accessible to research and free to access
    • The section containing the marker SHOULD be located where it can be visited quickly and SHOULD be kept in good condition (ideally a national reserve), in accessible terrain, extensive enough to allow repeated sampling and open to researchers of all nationalities
  7. The fossil content in the boundary interval SHOULD be abundant, distinctive, well preserved, and represent a fauna and/or flora as cosmopolitan and as diverse as possible.
  8. In order to ensure its acceptance and use in the Earth sciences, a boundary stratotype SHOULD contain as many specific marker horizons or other attributes as possible favorable for long-distance correlation.
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GSSP Tables

Quaternary

Stage / Interval Age (Ma) GSSP Location Longitude, Latitude Boundary Level Correlation Events Status Reference
Phanerozoic Eon
Cenozoic Era
Quaternary Period
Holocene Epoch
Meghalayan 0.0042 Mawmluh Cave, Meghalaya, India 91.715, 25.262222 depth 7.45 mm in the speleothem KM-A Climatic - 4.2 ka event Ratified 2018 Episodes 2018; 41: 213-223
Northgrippian 0.0082 North Greenland Ice Core Project, core NGRIP1, central Greenland ice sheet -42.32, 75.1 1228.67 m in the NGRIP1 ice core Climatic – 8.2 ka event Ratified 2018 Episodes 2018; 41: 213-223
Greenlandian 0.0117 North Greenland Ice Core Project, core NGRIP2, central Greenland ice sheet -42.32, 75.1 1492.45 m in the NGRIP2 ice core Climatic - End of the Younger Dryas Chron which is reflected in an abrupt shift to lower deuterium excess values Holocene GSSP ratifed 2008; Lower Holocene Subseries and Greenlandian Stage ratified: 2018 Episodes 2008; 31: 264–267
Episodes 2018; 41: 213-223
https://stratigraphy.org/gssps/files/meghalayan.pdf
Pleistocene Epoch
Chibanian 0.774 Chiba section, Japan 140.1465, 35.2943 lower boundary of the Byk-E tephra bed Magnetic - GSSP is 1.1 m below the directional midpoint of the Matuyama/Brunhes paleomagnetic reversal and occurs immediately below the top of Marine Isotope Substage (MIS) 19c. Ratified 2020 Episodes 2021; 44:317-347
Calabrian 1.80 Vrica, Italy 17.1348, 39.0385 base of the marine claystone overlying the sapropelic marker Bed 'e' (Mediterranean Precession Related Sapropel, MPRS 176) Magnetic - ∼8m below the observed top of the Olduvai (C2n) normal polarity subchron. GSSP level coincides with the transition from MIS 65 to 64 Ratified 1985 as base of Pleistocene; Ratified 2011 as base of Calabrian Quaternary Sci. 2019; 500: 32-51,
Episodes 1985; 8:116-120
Episodes 2012; 35: 388-397
Gelasian 2.58 Monte San Nicola, Sicily, Italy 14.2035, 37.1469 base of marly layer overlying sapropel MPRS 250 Magnetic - Matuyama/Gauss boundary (C2r/C2An) is between ~0 and ~3 m above GSSP (Head, 2019) not ∼1 m (20 kyr) below it as reported by Rio et al. (1994, 1998). GSSP level is within Marine Isotope Stage 103. Ratified 1996 as base of Gelasian; Ratified 2009 as base of Pleistocene and Quaternary Quaternary Sci. 2019; 500: 32-51,
Episodes 1998; 21: 82-87
Episodes 2010; 33: 152-158

Neogene

Stage / Interval Age (Ma) GSSP Location Longitude, Latitude Boundary Level Correlation Events Status Reference
Phanerozoic Eon
Cenozoic Era
Neogene Period
Pliocene Epoch
Piacenzian 3.600 Punta Piccola, Sicily, Italy 13.4933, 37.2889 base of the beige marl bed of small-scale carbonate cycle 77 (MPRS 347) Magnetic - Gauss/Gilbert (C2An/C2Ar) magnetic reversal is recorded immediately above the GSSP Ratified 1997 Episodes 1998; 21: 88-93
Zanclean 5.333 Eraclea Minoa, Sicily, Italy 13.2806, 37.3917 base of the Trubi Formation which corresponds to Insolation cycle 510 Magnetic - base of the Thvera magnetic event (C3n.4n) is only 96 kyr (5 precession cycles) younger than the GSSP. Ratified 2000 Episodes 2000; 23: 179-187
Miocene Epoch
Messinian 7.246 Oued Akrech, Morocco -6.8125, 33.9369 reddish layer of sedimentary cycle number 15 Planktonic foraminifer first regular occurrence of Globorotalia miotumida, and calcareous nannofossil FAD Amaurolithus delicatus Ratified 2000 Episodes 2000; 23: 172-178
Tortonian 11.63 Monte dei Corvi Beach, near Ancona, Italy 13.5661724, 43.587292 mid-point of sapropel layer of basic cycle number 76. Calcareous nannofossil last common occurrence of Discoaster kugleri Ratified 2003 Episodes 2005; 28: 6-17
Serravallian 13.82 Ras il Pellegrin section, Fomm Ir- Rih Bay, west coast of Malta 14.3361, 35.9139 formation boundary between the Globigerina Limestone and Blue Clay Oxygen-isotopic event (global cooling episode) Mi3b; near calcareous nannofossil LAD of Sphenolithus heteromorphus Ratified 2007 Episodes 2009; 32: 152-166
Langhian 15.98 'Lower La Vedova Beach' section, near Ancona, Italy 13.56229, 43.59193 Mid-point of the darker marly interval above 'Megabed IV' Closely to the top of magnetic polarity chronozone C5Cn.1n. Ratified 2023 Episodes 2024; 47:311-333
Aquitanian 23.03 Lemme-Carrosio Section, Allessandria Province, Italy 8.8364, 44.6589 35m from the top of the section Magnetic - base of Chron C6Cn.2n; planktonic foraminifer FAD of Paragloborotalia kugleri; calcareous nannofossil near LAD Reticulofenestra bisecta (base Zone NN1); Oxygen isotopic event Mi-1. Ratified 1996 Episodes 1997; 20: 23-28

Paleogene

Stage / Interval Age (Ma) GSSP Location Longitude, Latitude Boundary Level Correlation Events Status Reference
Phanerozoic Eon
Cenozoic Era
Paleogene Period
Oligocene Epoch
Chattian 27.30 Monte Cagnero, Umbria-Marche region, Italy 12.467731, 43.646614 Highest common occurrence (HCO) of Chiloguembelina cubensis Oxygen isotope excursion possibly related to the Oi2a glaciation event Ratified 2016 Episodes, 41 (1): 17-32.
Rupelian 33.9 Massignano, near Ancona, Italy 13.6011, 43.5328 base of a 0.5m thick greenishgrey marl bed 19m above base of section Foraminifer LAD Hantkenina and Cribrohantkenina Ratified 1992 Episodes 2001; 16: 379-382
Eocene Epoch
Priabonian 37.71 Alano section, Piave River; Veneto Prealps, Belluno province, N. Italy 11.918, 45.9142 The base of a prominent crystal tuff layer, the Tiziano bed, at meter 63.57 Extinction of large acarininids and Morozovelloides crassatus; the Base of common and continuous Cribrocentrum erbae and the Top of Chiasmolithus grandis; the Base of Chron C17n and Subchron C17n.2n Ratified 2020 Episodes 2021; 44(2): 151-173
Lutetian 48.07 Gorrondatxe section, Basque Country, Spain -3.0143, 43.3796 dark marl at 167.85 m in Gorrondatxe sea-cliff section LO of calcareous nannofossil Blackites inflatus (CP12a/b boundary); middle of polarity Chron C21r Ratified 2011 Episodes 2011; 34: 86-108
Ypresian 56.00 Dababiya, near Luxor, Egypt 32.5311, 25.5 Base of Bed 1 in DBH subsection Carbon Isotope Excursion base, initiation of basal Eocene Thermal maximum ("PETM") Ratified 2003 Episodes 2007; 30: 271-286
Micropaleontology 49/1, p.41 - 59, 2003
Paleocene Epoch
Thanetian 59.24 Zumaia section, northern Spain -2.2594, 43.3006 30.5m above the base of Itzurun Formation Magnetic - Base of Chron C26n Ratified 2008 Episodes 2011; 34: 220-243
Selandian 61.66 Zumaia section, northern Spain -2.2594, 43.3006 base of the red marls of Itzurun Formation 2nd radiation of the calcareous nannofossil group Fasciculithus and sea-level fall Ratified 2008 Episodes 2011; 34: 220-243
Danian 66.00 Oued Djerfane, west of El Kef, Tunisia 8.6486, 36.1537 reddish layer at the base of the 50cm thick, dark boundary clay Iridium geochemical anomaly. Associated with a major extinction horizon (dinosaurs, ammonites, foraminifers, etc.) Ratified 1991 Episodes 2006; 29: 263-278

Cretaceous

Stage / Interval Age (Ma) GSSP Location Longitude, Latitude Boundary Level Correlation Events Status Reference
Phanerozoic Eon
Mesozoic Era
Cretaceous Period
Upper Cretaceous Epoch
Maastrichtian 72.2 ± 0.2 Tercis les Bains, Landes, France -1.1133, 43.6795 level 115.2 on platform IV of the geological site at Tercis les Bains Mean of 12 biostratigraphic criteria of equal importance. Closely above is FAD of ammonite Pachydiscus neubergicus. Boreal proxy is FAD of belemnite Belemnella lanceolata. Ratified 2001 Episodes 2001; 24: 229-238
Campanian 83.6 ± 0.2 1.4 km NNE from the town of Gubbio, central Italy 12.58283, 43.36267 Level 221.53 m in the Bottaccione Gorge section at Gubbio, Umbria-Marche Basin, Italy The magnetic polarity reversal from Chron 34n (top of the Long Cretaceous Normal Polarity-Chron) to Chron C33r. Ratified 2022 DOI: 10.18814/epiiugs/2022/022048
Santonian 85.7 ± 0.2 Olazagutia, Navarra, Spain -2.1968, 42.8668 94.4 m in the Cantera de Margas quarry section the FO of the inoceramid bivalve Platyceramus undulatoplicatus Ratified 2013 Episodes 2014; 37: 2-13
Coniacian 89.8 ± 0.3 Salzgitter-Salder, Lower Saxony, Germany 10.3295, 52.1243 base of Bed 46 in the Salzgitter-Salder section first occurrence of the inoceramid Cremnoceramus deformis erectus Ratified 2021 DOI: 10.18814/epiiugs/2021/021022
Turonian 93.9 ± 0.2 Pueblo, Colorado, USA -104.7275, 38.2822 base of Bed 86 of the Bridge Creek Limestone Member Ammonite FAD Watinoceras devonense Ratified 2003 Episodes 2005; 28: 93-104
Cenomanian 100.5 ± 0.1 Mount Risou, Hautes-Alpes, France 5.5119, 44.3925 36 meters below the top of the Marnes Bleues Formation on the south side of Mont Risou Planktonic foraminifer FAD Rotalipora globotruncanoides Ratified 2002 Episodes 2004; 27: 21-32
Lower Cretaceous Epoch
Albian 113.2 ± 0.3 Col de Pré-Guittard, Department of Drôme, southeastern France 5.2973, 44.5079 37.4 m above the base of the section and 0.4 m above the base of the laminated Niveau Kilian bed Lowest occurrence of the planktonic foraminifer Microhedbergella renilaevis Ratified 2016 Episodes 40/3, p. 177-188, 2017
Barremian 125.77 Río Argos section near Caravaca, Murcia Province, Spain -1.9484, 38.0704 base of Bed 171 FAD of ammonite species Taveraidiscus hugii (Spitidiscus hugii - Spitidiscus vandeckii group), within calcareous nannofossil Subzone NC5C and in the lowermost part of polarity chron M3r. Ratified 2023 Episodes 2024; 47:335-379
Hauterivian 132.6 ± 0.6 La Charce, Department of Drôme, southeastern France 5.4437, 44.4694 base of bed 189 in the La Charce section First occurrence of the ammonite genus Acanthodiscus which marks the base of the Acanthodiscus radiatus ammonite Zone Ratified 2019 Episodes 2021; 44(2): 129-150

Jurassic

Stage / Interval Age (Ma) GSSP Location Longitude, Latitude Boundary Level Correlation Events Status Reference
Phanerozoic Eon
Mesozoic Era
Jurassic Period
Upper Jurassic Epoch
Kimmeridgian 154.8 ± 0.8 Flodigarry, Isle of Skye, NW Scotland -6.2455, 57.661 Base of Subboreal ammonite Baylei Zone, Base of Densicostata Subzone marked by the base of the flodigarriensis horizon; Base of Boreal ammonite Bauhini Zone. Ratified 2021 Episodes 2023; 46(2): 281-307
Middle Jurassic Epoch
Bathonian 168.2 ± 1.2 Ravin du Bès, Bas-Auran area, Alpes de Haute Provence, France 6.3153, 43.9606 base of limestone bed RB07 Ammonite FAD Gonolkite convergens (defines base of Zigzagiceras zigzag Zone) Ratified 2008 Episodes 2009; 32: 222-248
Bajocian 170.9 ± 0.8 Murtinheira Section, Cabo Mondego, Portugal -8.9042, 40.1992 base of Bed AB 11 Ammonite FAD Hyperlioceras mundum, Hyperlioceras furcatum, Braunsina aspera, and Braunsina elegantula Ratified 1996 Episodes 1997; 20: 16-22
Aalenian 174.7 ± 0.8 Fuentelsaz, Spain -1.8333, 41.1708 base of Bed FZ 107 Ammonite FAD Leioceras opalinum and Leioceras lineatum Ratified 2000 Episodes 2001; 24: 166-175
Lower Jurassic Epoch
Toarcian 184.2 ± 0.3 Peniche (Portugal) -9.3853, 39.3708 base of bed 15e (Couches de passage), uppermost Lemede Formation FO of the ammonite D. (E.) simplex co-occurring with D. (E.) pseudocommune and D. (E.) polymorphum . Ratified 2014 Episodes 2016; 39(3): 460-481
Pliensbachian 192.9 ± 0.3 Wine Haven, Robin Hood's Bay, Yorkshire Coast, England -0.4975, 54.4069 base of Bed 73b Ammonite association of Bifericeras donovani and Apoderoceras sp. Ratified 2005 Episodes 2006; 29: 93-106
Sinemurian 199.5 ± 0.3 East Quantoxhead, SW England -3.2364, 51.1909 0.90 m above the base of Bed 145 Ammonite FAD Vermiceras quantoxense, Vermiceras palmeri Ratified 2000 Episodes 2002; 25: 22-28
Hettangian 201.4 ± 0.2 Kuhjoch section, Tyrol, Austria 11.5306, 47.4839 5.80 m above top of Koessen Formation FO of ammonite Psiloceras spelae tirolicum, FO of aragonitic foraminifer Praegubkinella turgescens Ratified 2010 Episodes 2013; 36: 162-198

Triassic

Stage / Interval Age (Ma) GSSP Location Longitude, Latitude Boundary Level Correlation Events Status Reference
Phanerozoic Eon
Mesozoic Era
Triassic Period
Upper Triassic Epoch
Carnian 237 Prati di Stuores, Dolomites, Italy 11.9303, 46.5269 base of marly limestone bed SW4, 45m from base of San Cassiano Formation FAD of the ammonoid Daxatina canadensis; just below FO of conodont Paragondolella polygnathiformis and base of normal-polarity magnetic zone S2n Ratified 2008 Episodes 2012; 35: 414-430
Middle Triassic Epoch
Ladinian 241.464 ± 0.28 Bagolino, Province of Brescia, Northern Italy 10.471, 45.8193 base of a 15 - 20cm thick limestone bed overlying a distinctive groove ("Chiesense groove") of limestone nodules in a shaly matrix, located about 5m above the base of the Buchenstein Beds Ammonite FAD Eoprotrachyceras curionii (base of the E. curionii zone). Conodont FAD. Budurovignathus praehungaricus is in the uppermost Anisian. Ratified 2005 Episodes 2005; 28: 233-244
Anisian 247.0 Candidate section at Desli Caira (Dobrogea, Romania); significant sections in Guizhou Province (China) and South Primorye (Russia) 28.8022, 45.0742 In Section B, the GSSP level will be either the FAD of conodont Chiosella timorensis at the base of Bed GR7 at ca. 7 m; OR the base of magnetozone MT1n at the 5.7 m level. Conodont FAD Chiosella timorensis or Magnetic - base of magnetic polarity MT1n Proposed Krystyn, L., Richoz, S., & Bhargava, O. N. (2007). The Induan-Olenekian Boundary (IOB) in Mud–an update of the candidate GSSP section M04. Albertiana, 36, 33-45.
Lower Triassic Epoch
Olenekian 250.8 Candidate GSSP Mud (Muth) village, Spiti valley, northwest India 78.0246, 31.9654 base of Bed 13A-2, about 4.8m up in Mikin Formation., Section M04 (~4000 m elevation Conodont FAD Neospathodus waageni, just above base of Rohillites rohilla ammonite zone, and below lowest occurrence of Flemingites and Euflemingites ammonite genera. Within a prominent positive Carbon-13 peak, and just above widely recognizable sequence boundary. Proposed Krystyn, L., Richoz, S., & Bhargava, O. N. (2007). The Induan-Olenekian Boundary (IOB) in Mud–an update of the candidate GSSP section M04. Albertiana, 36, 33-45.
Induan 251.902 ± 0.024 Meishan, Zhejiang Province, China 119.7058, 31.0798 base of Bed 27c in the Meishan D Section Conodont FAD Hindeodus parvus Ratified 2001 Episodes 2001; 24: 102-114

Permian

Stage / Interval Age (Ma) GSSP Location Longitude, Latitude Boundary Level Correlation Events Status Reference
Phanerozoic Eon
Paleozoic Era
Permian Period
Lopingian Epoch
Changhsingian 254.14 ± 0.07 Meishan, Zhejiang Province, China 119.7064, 31.0819 base of Bed 4a- 2, 88 cm above the base of the Changxing Limestone at the Meishan D Section Conodont FAD Clarkina wangi Ratified 2005 Episodes 29/3 p. 175-182. 2006
Wuchiapingian 259.857 ± 0.084 Penglaitan, Guanxi Province, South China 109.3211, 23.6953 base of Bed n6L in the newly exposed Penglaitan section Conodont FAD Clarkina postbitteri Ratified 2004, Redefinition ratified 2023 Episodes 2006; 29/4:253-262
Episodes 2024; 47:147-177
Guadalupian Epoch
Capitanian 264.28 ± 0.16 Nipple Hill, SE Guadalupe Mountains, Texas, U.S.A -104.7892, 31.9091 4.5m above the base of the outcrop section of the Pinery Limestone Member of the Bell Canyon Formation Conodont FAD Jinogondolella postserrata Ratified 2001 Permophiles 34 p. 3-11, 1999
Episodes 45/3 p. 309-331. 2022
Wordian 266.9 ± 0.4 Guadalupe Pass, Texas, U.S.A -104.8328, 31.8658 7.6m above the base of the Getaway Ledge outcrop Section of the Getaway Limestone Member of the Cherry Canyon Formation Conodont FAD Jinogondolella aserrata Ratified 2001 Permophiles 34 p. 3-11, 1999
Wu et al. 2020 Palaeogeography Palaeoclimatology Palaeoecology 548 109668
Roadian 274.4 ± 0.4 Stratotype Canyon, Texas, U.S.A -104.8768, 31.8767 42.7m above the base of the Cutoff Formation Conodont FAD Jinogondolella nankingensis Ratified 2001 Permophiles 34 p. 3-11, 1999
Shen et al. 2020- Earth-Sci Rev 211 103412
Cisuralian Epoch
Artinskian 290.1 ± 0.26 Dalny Tulkas section, Southern Ural Mts, Russia 56.51615, 53.88847 0.6m above the base of bed 4b at the Dal'ny Tulkas section in the southern Urals of Russia Conodont FAD Sweetognathus asymmetricus Ratified 2022 Episodes 46/4, p. 623-651. 2023
Sakmarian 293.52 ± 0.17 Usolka section, Southern Ural Mts, Russia 56.7287, 53.9247 55.4 m (Bed 26/3) in the Usolka section Conodont FAD Mesogondolella monstra Ratified 2018 Episodes 43/4, 961-979, 2020
Asselian 298.9 ± 0.15 Aidaralash Creek, Kazakhstan 57.8914, 50.2458 27m above the base of Bed 19, Aidaralash Creek Conodont FAD Streptognathodus isolatus Ratified 1996 Episodes 21/1, 11-18, 1998

Carboniferous

Stage / Interval Age (Ma) GSSP Location Longitude, Latitude Boundary Level Correlation Events Status Reference
Phanerozoic Eon
Paleozoic Era
Carboniferous Period
Pennsylvanian Sub-Period
Lower Pennsylvanian Epoch
Bashkirian 323.4 ± 0.4 Arrow Canyon, Nevada -114.7778, 36.7333 82.9m above the top of the Battleship Formation in the lower Bird Spring Formation Conodont FAD Declinognathodus noduliferus Ratified 1996 Episodes 1999; 22: 272-283
Mississippian Sub-Period
Middle Mississippian Epoch
Visean 346.7 ± 0.4 Pengchong, south China 109.45, 24.4333 base of bed 83 in the Pengchong Section Benthic Foraminifer FAD Eoparastaffella simplex Ratified 2008 Episodes 2003; 26: 105-115
Lower Mississippian Epoch
Tournaisian 358.86 ± 0.19 La Serre, France 3.3573, 43.5555 base of Bed 89 in Trench E' at La Serre, (but FAD now known to be at base of Bed 85) Conodont FAD Siphonodella sulcata IMPRECISE (GSSP discovered in 2006 to have biostratigraphic problems, and can not be correlated with precision.) Ratified 1990 Episodes 1991; 14: 331-336
Newsletters on Stratigraphy 2009; 43: 195-205

Devonian

Stage / Interval Age (Ma) GSSP Location Longitude, Latitude Boundary Level Correlation Events Status Reference
Phanerozoic Eon
Paleozoic Era
Devonian Period
Upper Devonian Epoch
Famennian 372.15 ± 0.46 Coumiac Quarry, near Cessenon, Montagne Noire, France 3.0403, 43.4613 Base of Bed 32a Conodont FAD Palmatolepis triangularis, just above a major extinction horizon (Kellwasser Event) with conodont LADs Ancyrodella and Ozarkodina, and Goniatite LADs of Gephuroceratidae and Beloceratidae Ratified 1993 Episodes 1993; 16: 433-441
Frasnian 382.31 ± 1.36 Col du Puech de la Suque, Montage Noire, France 3.0868, 43.5032 base of Bed 42' at Col du Puech de la Suque section E Conodont FAD Ancyrodella rotundiloba Ratified 1986 Episodes 1987; 10: 97-101
Middle Devonian Epoch
Givetian 387.95 ± 1.04 Jebel Mech Irdane, Morocco -4.3541, 31.2374 base of Bed 123 Conodont FAD Polygnathus hemiansatus Ratified 1994 Episodes 1995; 18: 107-115
Eifelian 393.47 ± 0.99 Wetteldorf, Eifel Hills, Germany 6.4716, 50.1496 21.25m above the base of the exposed section, base of sample station WP30 Conodont FAD Polygnathus costatus partitus Ratified 1985 Episodes 1985; 8: 104-109
Lower Devonian Epoch
Emsian 410.62 ± 1.95 Zinzil'ban Gorge in the Kitab State Geological Reserve, Uzbekistan 67.3056, 39.2 base of Bed 9/5 Conodont FAD Polygnathus kitabicus Ratified 1995 Episodes 1997; 20: 235-240
Pragian 413.02 ± 1.91 Velká Chuchle, Prague, Czech Republic 14.3726, 50.0147 base of Bed 12 in Velká Chuchle Quarry Conodont FAD Eognathodus sulcatus sulcatus and Latericriodus steinachensis Morph beta Ratified 1989 Episodes 1989; 12: 109-113
Lochkovian 419.62 ± 1.36 Klonk, near Prague, Czech Republic 14.0611, 49.9008 within Bed 20 Graptolite FAD Monograptus uniformis Ratified 1972 Facies 26, 35–54
Newsletters on Stratigraphy 25, 115–125
The Geologic Time Scale 2020
IUGS Series A, 5, p. 96-109, 1977

Silurian

Stage / Interval Age (Ma) GSSP Location Longitude, Latitude Boundary Level Correlation Events Status Reference
Phanerozoic Eon
Paleozoic Era
Silurian Period
Pridoli 422.7 ± 1.6 Požáry Section, Reporyje, Prague, Czech Republic 14.3249, 50.0277 within Bed 96 Graptolite FAD Monograptus parultimus Ratified 1984 Episodes 1985; 8: 101-103
Geol. Series, Nat. Mus. Wales, 9, p. 90 - 100, 1989
Ludlow Epoch
Ludfordian 425.0 ± 1.5 near Ludlow, UK -2.7772, 52.3592 coincident with the base of the Leintwardine Formation Imprecise. May be near base of Saetograptus leintwardinensis Graptolite zone. Ratified 1980 Episodes 1982; 5: 21-23
Geol. Series, Nat. Mus. Wales 1989; 9: 73-90
Lethaia 14
Gorstian 426.7 ± 1.5 near Ludlow, UK -2.7772, 52.3592 coincident with the base of the Lower Elton Formation Graptolite FAD Saetograptus (Colonograptus) varians Ratified 1980 Episodes 1982; 5: 21-23
Geol. Series, Nat. Mus. Wales 1989; 9: 73-90
Lethaia 14
Wenlock Epoch
Homerian 430.6 ± 1.3 Sheinton Brook, Homer, UK -2.5647, 52.6156 within upper part of the Apedale Member of the Coalbrookdale Formation Graptolite FAD Cyrtograptus lundgreni Ratified 1980 Episodes 1982; 5: 21-23
Geol. Series, Nat. Mus. Wales 1989; 9: p. 51-73
Lethaia 14
Sheinwoodian 432.9 ± 1.2 Hughley Brook, UK -2.6389, 52.5811 base of the Buildwas Formation Imprecise. Between the base of acritarch biozone 5 and LAD of conodont Pterospathodus amorphognathoides. The current GSSP does not coincide with the base of the Cyrtograptus centrifugus Biozone, as was supposed when the GSSP was defined. Restudy recommends a slightly higher and correlatable level on condonts - the Ireviken datum 2, which coincides approximately with the base of the murchisoni Graptolite Biozone Ratified 1980 Episodes 1982; 5: 21-23
Geol. Series, Nat. Mus. Wales 1989; 9: p. 51-73
Lethaia 14
Llandovery Epoch
Telychian 438.6 ± 1.0 El Pintado 1 Section, Sierra Norte de Sevilla, Spain -5.9285, 37.9853 Unnamed Graptolite FADs of Spirograptus guerichi, Monograptus s.s. and Paradiversograptus runcinatus. Ratified 2024 to replace Cefn-Cerig Rd, Wales, UK former GSSP Episodes 1985; 8: 101-103
Cefn-Cerig Rd GSSP: Geol. Series, Nat. Mus. Wales 1989; 9: 36-50
El Pintado 1 GSSP: Loydell et al., Episodes forthcoming
Aeronian 440.5 ± 1.0 Hlásná Třebaň, Bohemia, Czech Republic -14.2119, 49.923 within Želkovice Formation, 1.38 m above base Graptolite FAD Demirastrites Triangulates Ratified 2024; to replace Trefawr Track, Wales, UK former GSSP Episodes 1985; 8: 101-103
Hlásná Třebaň GSSP: Štorch et al., Episodes forthcoming
Trefawr Track GSSP: Geol. Series, Nat. Mus. Wales 1989; 9: 36-50
Rhuddanian 443.1 ± 1.0 Dob's Linn, Scotland -3.27, 55.44 1.6m above the base of the Birkhill Shale Formation Graptolite FAD Akidograptus ascensus Ratified 1984 Episodes 1985; 8: 101-103
Silurian Times No. 14 (2006)

Ordovician

Stage / Interval Age (Ma) GSSP Location Longitude, Latitude Boundary Level Correlation Events Status Reference
Phanerozoic Eon
Paleozoic Era
Ordovician Period
Upper Ordovician Epoch
Hirnantian 445.2 ± 0.9 Wangjiawan North section, N of Yichang city, Western Hubei Province, China 111.4197, 30.9841 0.39m below the base of the Kuanyinchiao Bed Graptolite FAD Normalograptus extraordinarius Ratified 2006 Episodes 2006; 29: 183-196
Katian 452.8 ± 0.7 Black Knob Ridge Section, Atoka, Oklahoma (USA) -96.0746, 34.4305 4.0m above the base of the Bigfork Chert Graptolite FAD Diplacanthograptus caudatus Ratified 2006 Episodes 2007; 30: 258-270
Sandbian 458.2 ± 0.7 Sularp Brook, Fågelsång, Sweden 13.3255, 55.7137 1.4m below a phosphorite marker bed in the E14b outcrop Graptolite FAD Nemagraptus gracilis Ratified 2002 Episodes 2000; 23: 102-109
Middle Ordovician Epoch
Darriwilian 469.4 ± 0.9 Huangnitang section, Changshan, Zhejiang Province, SE China 118.4897, 28.8539 base of Bed AEP 184 Graptolite FAD Undulograptus austrodentatus Ratified 1987 Episodes 1997; 20: 158-166
Dapingian 471.3 ± 1.4 Huanghuachang Section, NE of Yichang city, Hubei Province, S. China 110.374, 30.8605 10.57 m above base of the Dawan Formation Conodont FAD of Baltoniodus triangularis Ratified 2007 Episodes 2005; 28: 105-117
Episodes 2009; 32: 96-113
Lower Ordovician Epoch
Floian 477.1 ± 1.2 Diabasbrottet, Hunneberg, Sweden 12.5024, 58.3589 in the lower Tøyen Shale, 2.1m above the top of the Cambrian Graptolite FAD Tetragraptus approximatus Ratified 2002 Episodes 2004; 27: 265-272
Tremadocian 486.85 ± 1.5 Green Point Section, western Newfoundland -57.9653, 49.6829 at the 101.8m level, within Bed 23, in the measured section Conodont FAD Iapetognathus fluctivagus Ratified 2000 Episodes 2001; 24: 19-28

Cambrian

Stage / Interval Age (Ma) GSSP Location Longitude, Latitude Boundary Level Correlation Events Status Reference
Phanerozoic Eon
Paleozoic Era
Cambrian Period
Furongian Epoch
Jiangshanian 494.2 Duibian B section, Zhejiang province, China 118.6149, 28.8158 28.2 m in Duibian B section FAD of agnostid trilobite Agnostotes orientalis and the FO of polymerid trilobite Irvingella angustilimbata Ratified 2011 Episodes 2012; 35: 462-477
Paibian 497.0 Wuling Mountains, Huayuan County, NW Hunan Province, Chin 109.5257, 28.3895 at 396 m in the Huaqiao Formation Trilobite FAD Glyptagnostus reticulatus Ratified 2003 Lethaia 37, p. 365-379, 2004
Miaolingian Epoch
Guzhangian 500.5 Louyixi, Guzhang County, NW Hunan Province, S. China 109.9647, 28.72 121.3 m above the base of the Huaqiao Formation Trilobite FAD Lejopyge laevigata Ratified 2008 Episodes 2009; 32: 41-55
Drumian 504.5 Drum Mountains, Millard County, Utah, USA -112.9915, 39.5117 at the base of a dark-gray thinly laminated calcisiltite layer, 62 m above the base of the Wheeler Formation Trilobite FAD Ptychagnostus atavus Ratified 2006 Episodes 2007; 30: 85-95
Terreneuvian Epoch
Fortunian 538.8 ± 0.6 Fortune Head, SE Newfoundland, Canada -55.831, 47.0762 2.4m above the base of Member 2 in the Chapel Island Formation Trace fossil FAD Trichophycus pedum Ratified 1992 Episodes 1994; 17: 95-100

Ediacaran

Stage / Interval Age (Ma) GSSP Location Longitude, Latitude Boundary Level Correlation Events Status Reference
Precambrian Super-Eon
Proterozoic Eon
Neoproterozoic Era
Ediacaran Period
Ediacaran 635 Enorama Creek, Flinders Ranges, South Australia 138.6334, -31.3314 base of the Marinoan cap carbonate (1) rapid decay of Marinoan ice sheets and onset of distinct cap carbonates throughout the world, and (2) the beginning of a distinctive pattern of secular changes in carbon isotopes. Ratified 1990 Lethaia 39, p.13- 30, 2006

GSSAs & SABS

Phanerozoic

Stage / Interval Age (Ma) GSSP Location Longitude, Latitude Boundary Level Correlation Events Status Reference
Phanerozoic Eon
Cenozoic Era
Quaternary Period
Pleistocene Epoch
Upper Pleistocene 0.129 GSSP not presently defined Provisionally climatic – Marine Isotope Substage 5e Proposed Head, M.J., Pillans, B., and Zalasiewicz, J.A., [submitted 2020]
Chibanian SABS 0.774 Ideale Section, Montalbano Jonico succession, Basilicata, S Italy 16.5518, 40.291 SABS holds high-resolution C and O stratigraphy and a sapropel bed through Termination IX and MIS 19c; peaking 10Be/9Be ratio at the Matuyama/Brunhes boundary interval; regional tephra beds. Ratified 2023 Episodes 2024; 47:121-146

Proterozoic

Stage / Interval Age (Ma) GSSP Location Longitude, Latitude Boundary Level Correlation Events Status Reference
Precambrian Super-Eon
Proterozoic Eon
Neoproterozoic Era
Cryogenian Period
Cryogenian 720 Will be placed at a that lies stratigraphically beneath the first appearance of widespread glaciation and is assigned in the interim a 'calibrated age' of circa 720 Ma Proposed Episodes 2019; 39
Tonian Period
Tonian 1000 Defined chronometrically Ratified 1990 Episodes 1991; 14
Mesoproterozoic Era
Stenian Period
Stenian 1200 Defined chronometrically Ratified 1990 Episodes 1991; 14
Ectasian Period
Ectasian 1400 Defined chronometrically Ratified 1990 Episodes 1991; 14
Calymmian Period
Calymmian 1600 Defined chronometrically Ratified 1990 Episodes 1991; 14
Paleoproterozoic Era
Statherian Period
Statherian 1800 Defined chronometrically Ratified 1990 Episodes 1991; 14
Orosirian Period
Orosirian 2050 Defined chronometrically Ratified 1990 Episodes 1991; 14
Rhyacian Period
Rhyacian 2300 Defined chronometrically Ratified 1990 Episodes 1991; 14
Siderian Period
Siderian 2500 Defined chronometrically, but it will be replaced by GSSP Ratified 1990 Episodes 1991; 14

Archean

Stage / Interval Age (Ma) GSSP Location Longitude, Latitude Boundary Level Correlation Events Status Reference
Precambrian Super-Eon
Archean Eon
Neoarchean Era
Neoarchean 2800 Defined chronometrically Proposed Informally in Episodes 1992; 15
Mesoarchean Era
Mesoarchean 3200 Defined chronometrically Proposed Informally in Episodes 1992; 15
Paleoarchean Era
Paleoarchean 3600 Defined chronometrically Proposed Informally in Episodes 1992; 15
Eoarchean Era
Eoarchean 4031 ± 3 Defined chronometrically along Acasta River, Northwestern Territory, Canada -115.5538, 65.1738 Acasta Gneiss Complex Fm., Slave Province, Canadian Shield Ten oldest zircon U-Pb ages Ratified 2023 Episodes, forthcoming (formal GSSA)
Succeeds Episodes 1992; 15 (informal 4000 Ma).

Hadean

Stage / Interval Age (Ma) GSSP Location Longitude, Latitude Boundary Level Correlation Events Status Reference
Precambrian Super-Eon
Hadean Eon
Hadean 4567 Defined chronometrically Data in Amelin et al., 2010 (Allende); Connelly et. al., 2012 (Gujba). Allende meteorite (1969, Chihuahua, Mexico) Gujba meteorite (1984, Bogga Dingar, Nigeria) Formation of planet Earth and sister Solar planets (protoplanetary disk), by proxy of ages obtained from primitive meteorites U-corrected Pb–Pb age for Calcium-Aluminium Inclusions (CAIs) in class CBa meteorite Ratified 2022 Episodes 2024; 47(2):381-389