Global Stratotype Sections and Points

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EON, Era, System, Series, Stages	Age (Ma) GTS 2004	Est. ±Ma	Derivation of age	Principal correlative events	GSSP and location	Status	Publication
PHANEROZOIC Eon
Cenozoic Era
Neogene System
QUATERNARY Sub-System	2.588	-	-	Quaternary is a formal Sub-System (Sub-Era) of the Cenozoic time scale. It is the interval of oscillating climatic extremes (glacial and interglacial episodes) that was initiated at about 2.6 Ma (set equal to base of Gelasian stage), therefore it encompasses the Holocene and Pleistocene epochs and the late Pliocene.	Equivalent to GSSP of Gelasian at Monte San Nicola, Gela, Sicily, Italy. Correlates with Marine Isotopic stage 103, and base of magnetic polarity chronozone C2r (Matuyama)	ICS formal recommendation to INQUA and ICS; Sept 2005.	Proposal in Episodes 28 (2), p.118-120, 2005
*Holocene Series*
base Holocene	0.011784	0.00	Annual layer counting in ice core ("ka" is relative to AD2000); counting uncertainy is 69 years	End of the Younger Dryas cold spell, which is reflected in a shift in deuterium excess values, followed closely by changes in d18O, dust concentration, a range of chemical species, and by a change in annual layer thickness	NorthGRIP ice core, Greenland	GSSP anticipated in 2005	-
*Pleistocene Series*
base upper Pleistocene Subseries	0.126	0.00	Astronomical cycles in sediments	base of the Eemian interglacial stage (= base of marine isotope stage 5e) before final glacial episode of Pleistocene	Amsterdam-Terminal borehole (63.5 m below surface; 52°22'45"N; 4°54'52"E), Netherlands	GSSP anticipated in 2006	-
base middle Pleistocene Subseries	0.781	0.00	Astronomical cycles in sediments	Brunhes-Matuyama magnetic reversal	Candidate sections in Italy (Montalbano Jorica or Valle di Manche) and Japan (Chiba)	GSSP anticipated in 2007	-
base Pleistocene Series	1.806	0.00	Astronomical cycles in sediments	Just above top of magnetic polarity chronozone C2n (Olduvai) and the extinction level of calcareous nannofossil Discoaster brouweri (base Zone CN13). Above are lowest occurrence of calcareous nannofossil medium Gephyrocapsa spp. and extinction level of planktonic foraminifer Globigerinoides extremus.	Top of sapropel layer 'e', Vrica section, Calabria, Italy	Ratified 1985	Episodes 8 (2), p.116-120, 1985
*Pliocene Series*
base Gelasian Stage	2.588	0.00	Astronomical cycles in sediments	Isotopic stage 103, base of magnetic polarity chronozone C2r (Matuyama). Above are extinction levels of calcareous nannofossil Discoaster pentaradiatus and D. surculus (base Zone CN12c).	Midpoint of sapropelic Nicola Bed ("A5"), Monte San Nicola, Gela, Sicily, Italy	Ratified 1996	Episodes 21 (2), p.82-87, 1998
base Piacenzian Stage	3.600	0.00	Astronomical cycles in sediments	Base of magnetic polarity chronozone C2An (Gauss); extinction levels of planktonic foraminifers Globorotalia margaritae (base Zone PL3) and Pulleniatina primalis.	Base of beige layer of carbonate cycle 77, Punta Piccola, Sicily, Italy	Ratified 1997	Episodes 21 (2), p.88-93, 1998
base Zanclean Stage, base Pliocene Series	5.332	0.00	Astronomical cycles in sediments	Top of magnetic polarity chronozone C3r, ~100 kyr before Thvera normal-polarity subchronozone (C3n.4n). Calcareous nannofossils -- near extinction level of Triquetrorhabdulus rugosus (base Zone CN10b) and the lowest occurrence of Ceratolithus acutus.	Base of Trubi Fm (base of carbonate cycle 1), Eraclea Minoa, Sicily, Italy	Ratified 2000	Episodes 23 (3), p.179-187, 2000
*Miocene Series*
base Messinian Stage	7.246	0.00	Astronomical cycles in sediments	Astrochronology age of 7.251 Ma; middle of magnetic polarity chronozone C3Br.1r; lowest regular occurrence of the Globorotalia conomiozea planktonic foraminifer group.	Base of red layer of carbonate cycle 15, Oued Akrech, Rabat, Morocco	Ratified 2000	Episodes 23 (3), p. 172-178, 2000
base Tortonian Stage	11.608	0.00	Astronomical cycles in sediments	Last Common Occurrences of the calcareous nannofossil Discoaster kugleri and the planktonic foraminifer Globigerinoides subquadratus. Associated with the short normal-polarity subchron C5r.2n.	Midpoint of sapropel 76, Monte dei Corvi beach section, Ancona, Italy	Ratified 2003	Episodes 28 (1), p.6-17, 2005
base Serravallian Stage	13.65	0.00	Astronomical cycles in sediments	Near lowest occurrence of nannofossil Sphenolithus heteromorphus, within magnetic polarity chronozone C5ABr, and Mi3b isotopic event (global cooling episode)	Candidate on Malta (Ras il Pellegrin section) at base of Blue Clay	GSSP anticipated in 2006	-
base Langhian Stage	15.97	0.00	Calibrated magnetic anomaly scale	Near first occurrence of planktonic foraminifer Praeorbulina glomerosa and top of magnetic polarity chronozone C5Cn.1n	Potentially in astronomically-tuned ODP core (Leg 154) or in Italy (Moria or La Vedere)	GSSP anticipated in 2008	-
base Burdigalian Stage	20.43	0.00	Calibrated magnetic anomaly scale	Near lowest occurrence of planktonic foraminifer Globigerinoides altiaperturus or near top of magnetic polarity chronozone C6An	Potentially in astronomically-tuned ODP core	Guide event is undecided. GSSP anticipated in 2008	-
base Aquitanian Stage, base Miocene Series, base Neogene System	23.03	0.00	Astronomical cycles in sediments	Base of magnetic polarity chronozone C6Cn.2n; lowest occurrence of planktonic foraminifer Paragloborotalia kugleri; near extinction of calcareous nannofossil Reticulofenestra bisecta (base Zone NN1).	35 m from top of Lemme-Carrosio section, Carrosio village, north of Genoa, Italy	Ratified 1996	Episodes 20 (1),p. 23-28, 1997
Paleogene System
*Oligocene Series*
base Chattian Stage	28.4	0.1	Calibrated magnetic anomaly scale relative to base-Miocene and C24n. Arbitrary 100 kyr uncertainty assigned.	Potentially extinction of planktonic foraminifer Chiloguembelina (base Foram Zone P21b); or an isotopic/climatic event	Possibly Monte Cagnero (Umbria-Marche region, Italy)	GSSP anticipated in 2006	-
base Rupelian Stage, base Oligocene Series	33.9	0.1	Calibrated magnetic anomaly scale relative to base-Miocene and C24n.	Planktonic foraminifer, extinction of Hantkenina	Base of marl bed at 19m above base of Massignano quarry, Ancona, Italy	Ratified 1992	Episodes 16 (3), p.379-382, 1993
*Eocene Series*
base Priabonian Stage	37.2	0.1	Calibrated magnetic anomaly scale relative to base-Miocene and C24n	Near lowest occurrence of calcareous nannofossil Chiasmolithus oamaruensis (base Zone NP18)	Tiziano Bed, Alano section (Piave River; Veneto Prealps, Belluno province, N. Italy)	GSSP anticipated in 2006	-
base Bartonian Stage	40.4	0.2	Calibrated magnetic anomaly scale relative to base-Miocene and C24n	Near extinction of calcareous nannofossil Reticulofenestra reticulata	-	GSSP anticipated in 2008	-
base Lutetian Stage	48.6	0.2	Calibrated magnetic anomaly scale relative to base-Miocene and C24n	Planktonic foraminifer, lowest occurrence of Hantkenina	Leading candidate is Agost section, Murcia province, Betic Cordilleras, Spain	GSSP anticipated in 2007	-
base Ypresian Stage, base Eocene Series	55.8	0.2	Astronomical cycles in sediments scaled from base-Paleocene	Base of negative carbon-isotope excursion	Dababiya Section near Luxor, Egypt	Ratified 2003	Micropaleontology v.49 (Suppl. 1), 2003. Episodes article in preparation
*Paleocene Series*
base Thanetian Stage	58.7	0.2	Astronomical cycles in sediments scaled from base Paleocene, using base of magnetic polarity chronozone C26n. Arbitrary 0.1 (2 precession cycles, plus the base-Paleogene radiometric) uncertainty assigned to all estimates.	Magnetic polarity chronozone, base of C26n	Leading candidate is Zumaya section, northern Spain	GSSP anticipated in 2007	-
base Selandian Stage	61.7	0.2	Astronomical cycles in sediments scaled from base Paleocene, using magnetic polarity chronozone placement of C27n.9	Undecided; possibilities include top or bottom of Foram Zone P3a, or C-13 excursion near base of calcareous nannofossil Zone NP5 (which would be ~1 myr younger than age estimate shown here)	Leading candidate is Zumaya section, northern Spain	Guide event is undecided. GSSP anticipated in 2007	-
base Danian Stage, base Paleogene System, base Cenozoic	65.5	0.3	Ar-Ar and U-Pb age agreement	Iridium geochemical anomaly. Associated with a major extinction horizon (foraminifers, calcareous nannofossils, dinosaurs, etc.);	Base of boundary clay, El Kef, Tunisia (but deterioration may require assigning a replacement section)	Ratified 1991	-
Mesozoic Era
Cretaceous System
Most Cretaceous substages also have recommended GSSP criteria
*Upper Cretaceous Series*
base Maastrichtian Stage	70.6	0.6	Estimated placement relative to Ar-Ar calibrated Sr-curve	Mean of 12 biostratigraphic criteria of equal importance. Closely above is lowest occurrence of ammonite Pachydiscus neubergicus. Boreal proxy is lowest occurrence of belemnite Belemnella lanceolata.	115.2 m level in Grande Carrière quarry, Tercis-les-Bains, Landes province, SW France	Ratified 2001	Episodes 24 (4), p.229-238, 2001; Odin (ed.) IUGS Spec. Publ. Series, v.36, Elsevier, 910pp.
base Campanian Stage	83.5	0.7	Spline fit of Ar-Ar ages and ammonite zones.	Crinoid, extinction of Marsupites testudinarius	Leading candidates are in southern England and in Texas	GSSP anticipated in 2008	-
base Santonian Stage	85.8	0.7	Spline fit of Ar-Ar ages and ammonite zones.	Inoceramid bivalve, lowest occurrence of Cladoceramus undulatoplicatus	Leading candidates are in Spain, England and Texas	GSSP anticipated in 2007	-
base Coniacian Stage	89.3	1.0	Spline fit of Ar-Ar ages and ammonite zones.	Inoceramid bivalve, lowest occurrence of Cremnoceramus rotundatus (sensu Tröger non Fiege)	Base of Bed MK47, Salzgitter-Salder Quarry, SW of Hannover, Lower Saxony, northern Germany	GSSP anticipated in 2006	-
base Turonian Stage	93.5	0.8	Spline fit of Ar-Ar ages and ammonite zones	Ammonite, lowest occurrence of Watinoceras devonense	Base of Bed 120, Rock Canyon Anticline, east of Pueblo, Colorado, west-central USA	Ratified 2003	Episodes 28(1), p. 93-104, 2005
base Cenomanian Stage	99.6	0.9	Spline fit of Ar-Ar ages and ammonite zones, plus monitor standard correction. Then cycle stratigraphy to place foraminifer datum relative to ammonite zonation.	Planktonic foraminifer, lowest occurrence of Rotalipora globotruncanoides	36 m below top of Marnes Bleues Formation, Mont Risou, Rosans, Haute-Alpes, SE France	Ratified 2002	Episodes 27 (1), p.21-32, 2004
*Lower Cretaceous Series*
base Albian Stage	112.0	1.0	Cycle-stratigraphy of FAD of P. columnata relative to base of Cenomanian, with large uncertainty due to lack of GSSP criteria	Candidates include: (1) calcareous nannofossil, lowest occurrence of Praediscosphaera columnata (= P. cretacea of some earlier studies), (2) carbon-isotope excursion (black-shale episode), (3) ammonite	-	Guide event is undecided. GSSP anticipated in 2008	-
base Aptian Stage	125.0	1.0	Base of M0r, as recomputed from Ar-Ar age from MIT guyot	Magnetic polarity chronozone, base of M0r; near base of Paradeshayesites oglanlensis ammonite zone	Leading candidate is Gorgo a Cerbara, Piobbico, Umbria-Marche, central Italy	GSSP anticipated in 2006	-
base Barremian Stage	130.0	1.5	Pacific spreading model for magnetic anomaly ages (variable rate), using placement at M5n.8.	Ammonite, lowest occurrence of Spitidiscus hugii – Spitidiscus vandeckii group	Leading candidate is Río Argos near Caravaca, Murcia province, Spain	GSSP anticipated in 2006	-
base Hauterivian Stage	136.4	2.0	Pacific spreading model for magnetic anomaly ages (variable rate), using placement at base M11n	Ammonite, lowest occurrence of genus Acanthodiscus (especially A. radiatus)	Leading candidate is La Charce village, Drôme province, southeast France	GSSP anticipated in 2006	-
base Valanginian Stage	140.2	3.0	Pacific spreading model for magnetic anomaly ages (variable rate), using placement at M14r.3 (base T. pertransiens).	Calpionellid, lowest occurrence of Calpionellites darderi (base of Calpionellid Zone E); followed by the lowest occurrence of ammonite “Thurmanniceras” pertransiens	Leading candidates are near Montbrun-les-Bains (Drôme province, SE France) and Cañada Luenga (Betic Cordillera, S. Spain)	GSSP anticipated in 2007	-
base Berriasian Stage, base Cretaceous System	145.5	4.0	Pacific spreading model for magnetic anomaly ages (variable rate), assigning to base of Berriasella jacobi zone (M19n.2n.55)	Maybe near lowest occurrence of ammonite Berriasella jacobi	-	Guide event is undecided. GSSP anticipated in 2008	-
Jurassic System
*Upper Jurassic Series*
base Tithonian Stage	150.8	4.0	Pacific spreading model for magnetic anomaly ages (variable rate), assigning to base M22An	Near base of Hybonoticeras hybonotum ammonite zone and lowest occurrence of Gravesia genus, and the base of magnetic polarity chronozone M22An	Candidates are Mt. Crussol or Canjuers (SE France) and Fornazzo (Sicily, S. Italy)	Guide event is undecided. GSSP anticipated in 2007	-
base Kimmeridgian Stage	155.7	4.0	Pacific spreading model for magnetic anomaly ages (variable rate), assigning to base M26r.2 (Boreal ammonite definition)	Ammonite, near base of Pictonia baylei ammonite zone of Boreal realm	Candidate is Flodigarry (Isle of Skye, NW Scotland)	GSSP anticipated in 2006	-
base Oxfordian Stage	161.2	4.0	Pacific spreading model for magnetic anomaly ages (variable rate), assigning to base M36An	Ammonite, Brightia thuouxensis Horizon at base of the Cardioceras scarburgense Subzone (Quenstedtoceras mariae Zone)	Leading candidates are Savouron (Provence province, SE France) and Redcliffe Point (Dorset, SW England)	GSSP anticipated in 2006	-
*Middle Jurassic Series*
base Callovian Stage	164.7	4.0	Equal subzones scale Bajo-Bath-Callov	Ammonite, lowest occurrence of the genus Kepplerites (Kosmoceratidae) (defines base of Macrocephalites herveyi Zone in sub-Boreal province of Great Britain to southwest Germany)	Leading candidate is Pfeffingen, Swabian Alb, SW Germany	GSSP anticipated in 2006	-
base Bathonian Stage	167.7	3.5	Equal subzones scale Bajo-Bath-Callov	Ammonite, lowest occurrence of Parkinsonia (G.) convergens (defines base of Zigzagiceras zigzag Zone)	Candidates are in Iberia, and near Digne (SE France)	GSSP anticipated in 2007	-
base Bajocian Stage	171.6	3.0	Equal subzones scale Bajo-Bath-Callov	Ammonite, lowest occurrence of the genus Hyperlioceras (defines base of the Hyperlioceras discites Zone)	Base of Bed AB11, 77.8 m above base of Murtinheira section, Cabo Mondego, western Portugal	Ratified 1996	Episodes 20 (1), p.16-22, 1997
base Aalenian Stage	175.6	2.0	Duration of Aalenian-Toarcian from cycle stratigraphy	Ammonite, lowest occurrence of Leioceras genus	base of Bed FZ107, Fuentelsalz, central Spain	Ratified 2000	Episodes 24 (3), p.166-175, 2001
*Lower Jurassic Series*
base Toarcian Stage	183.0	1.5	Duration of Aalenian-Toarcian from cycle stratigraphy	Ammonite, near lowest occurrence of a diversified Eodactylites ammonite fauna; correlates with the NW European Paltus horizon.	Peniche (Portugal)	GSSP anticipated in 2006	-
base Pliensbachian Stage	189.6	1.5	Cycle-scaled linear Sr trend	Ammonite, lowest occurrences of Bifericeras donovani and of genera Apoderoceras ((defines base of Phricodoceras taylori subzone of Uptonia jamesoni ammonite zone)	Base of Bed 73b, Wine Haven section, Robin Hood's Bay, Yorkshire, England, UK	Ratified 2005	Proposal in Eclogae Geol. Helv. 96, p.275-297, 2003. Episodes article in preparation
base Sinemurian Stage	196.5	1.0	Cycle-scaled linear Sr trend	Ammonite, lowest occurrence of arietitid genera Vermiceras and Metophioceras	0.9 m above base of Bed 145, East Quantoxhead, Watchet, West Somerset, SW England, UK	Ratified 2000	Episodes 25 (1), p. 22-26, 2002
base Hettangian Stage, base Jurassic System	199.6	0.6	U-Pb age just below proposed GSSP for base-Jurassic	Near lowest occurrence of smooth Psiloceras planorbis ammonite group	-	Guide event is undecided. GSSP anticipated in 2007	-
Triassic System
*Upper Triassic Series*
base Rhaetian Stage	203.6	1.5	Magnetostratigraphic correlation to cycle-scaled Newark magnetic polarity pattern	Near lowest occurrence of ammonite Cochlocera, conodonts Misikella spp. and Epigondolella mosheri, and radiolarian Proparvicingula moniliformis	Key sections in Austria, British Columbia (Canada), and Turkey	Guide event is undecided. GSSP anticipated in 2008	-
base Norian Stage	216.5	2.0	Magnetostratigraphic correlation to cycle-scaled Newark magnetic polarity pattern	Base of Klamathites macrolobatus or Stikinoceras kerri ammonoid zones and the Metapolygnathus communisti or M. primitius conodont zones	Leading candidates are in British Columbia (Canada), Sicily (Italy), and possibly Slovakia, Turkey (Antalya Taurus) and Oman.	Guide event is undecided. GSSP anticipated in 2008	-
base Carnian Stage	228.0	2.0	Magnetostratigraphic correlation to cycle-scaled Newark magnetic polarity pattern	Near first occurrence of the ammonoids Daxatina or Trachyceras, and of the conodont Metapolygnathus polygnathiformis	Candidate section at Prati di Stuores, Dolomites, northern Italy. Important reference sections in Spiti (India) and New Pass, Nevada (USA).	Guide event is undecided. GSSP anticipated in 2007	-
*Middle Triassic Series*
base Ladinian Stage	237.0	2.0	U-Pb array by Mundil et al. on levels near Nevadites (= Secedensis) ammonite zone in Dolomites, plus placement relative to magnetostratigraphy corrlations to cycle-scaled Newark magnetic polarity pattern	Ammonoid, lowest occurrence of the Eoprotrachyceras curionii (base of the E. curionii zone; onset of the Trachyceratidae family. Above lowest Neogondolella praehungarica conodont	Top of "Chiesense groove", 5m above base of Buchenstein Beds, Caffaro river bed, Bagolino (Brescia province, N. Italy)	Ratified 2005	Episodes article in preparation
base Anisian Stage	245.0	1.5	Proportional subzonal scaling	Conodont, lowest occurrences of Chiosella timorensis	Candidate section at Desli Caira (Dobrogea, Romania); significant sections in Guizhou Province (China) and South Primorye (Russia)	GSSP anticipated in 2007	-
*Lower Triassic Series*
base Olenekian Stage	249.7	0.7	Composite standard from conodonts scaled to base-Anisian and base-Triassic	Conodont, lowest occurrence of Neospathodus waageni; near lowest occurrence of Flemingites and Euflemingites ammonite genera	Chaohu (Anhui province, E. China). Important sections in Spiti	GSSP anticipated in 2006	-
base Induan Stage, base Triassic System, base Mesozoic	251.0	0.4	U-Pb ages bracket GSSP (Bowring et al., 1998)	Conodont, lowest occurrence of Hindeodus parvus; termination of major negative carbon-isotope excursion. About 1 myr after peak of Late Permian extinctions.	Base of Bed 27c, Meishan, Zhejiang, China	Ratified 2001	Episodes 24 (2), p.102-114, 2001
Paleozoic Era
Permian System
*Lopingian Series*
base Changhsingian Stage	253.8	0.7	Permian-Carboniferous time scale is derived from calibrating a master composite section to selected radiometric ages	Conodont, near lowest occurrence of conodont Clarkina wangi	Base of Bed 4a-2, 88 cm above base of Changxing Limestone, Meishan D section (Zhejiang province, E. China)	Ratified 2005	Episodes article in preparation
base Wuchiapingian Stage	260.4	0.7	"	Conodont, lowest occurrence of Clarkina postbitteri postbitteri		Ratified 2004	Episodes article in preparation
*Guadalupian Series*
base Capitanian Stage	265.8	0.7	"	Conodont, lowest occurrence of Jinogondolella postserrata	4.5 m above base of Pinery Limestone Member, Nipple Hill, SE Guadalupe Mountains, Texas, USA	Ratified 2001	Episodes article in preparation
base Wordian Stage	268.0	0.7	"	Conodont, lowest occurrence of Jinogondolella aserrata	7.6 m above base of Getaway Ledge outcrop, Guadalupe Pass, SE Guadalupe Mountains, Texas, USA	Ratified 2001	Episodes article in preparation
base Roadian Stage	270.6	0.7	"	Conodont, lowest occurrence of Jinogondolella nanginkensis	42.7 m above base of Cutoff Formation, Stratotype Canyon, southern Guadalupe Mountains, Texas, USA	Ratified 2001	Episodes article in preparation
*Cisuralian Series*
base Kungurian Stage	275.6	0.7	"	Near lowest occurrence of conodont Neostreptognathus pnevi - N. exculptus	Leading candidates are in southern Ural Mtns.	GSSP anticipated in 2007	-
base Artinskian Stage	284.4	0.7	"	Conodont, lowest occurrence of conodont Sweetognathus whitei	Leading candidates are in southern Ural Mtns.	GSSP anticipated in 2007	-
base Sakmarian Stage	294.6	0.8	"	Conodont, near lowest occurrence of conodont Sweetognathus merrelli	Leading candidate is at Kondurovsky, Orenburg Province, Russia.	GSSP anticipated in 2006	-
base Asselian Stage, base Cisuralian Series, base Permian System	299.0	0.8	"	Conodont, lowest occurrence of Streptognathodus isolatus within the S. "wabaunsensis" conodont chronocline. 6 m higher is lowest fusilinid foraminifer Sphaeroschwagerina vulgaris aktjubensis	27 m above base of Bed 19, Aidaralash Creek, Aktöbe, southern Ural Mountains, northern Kazakhstan	Ratified, 1996	Episodes 21 (1), p.11-18, 1998
Carboniferous System
*Pennsylvanian Subsystem* (series classification approved in 2004)
*Upper Pennsylvanian Series*
base Gzhelian Stage	303.9	0.9	"	Near lowest occurrences of the fusulinids Daixina, Jigulites and Rugosofusulina, or lowest occurrence of conodont Idiognathodus simulator (s.str.). Close to lowest occurrence of ammonoid Shumardites.	-	Guide event is undecided. GSSP anticipated in 2007	-
base Kasimovian Stage	306.5	1.0	"	Near base of Obsoletes obsoletes and Protriticites pseudomontiparus fusulinid zone, or lowest occurrence of Parashumardites ammonoid	-	Guide event is undecided. GSSP anticipated in 2008	-
*Middle Pennsylvanian Series*
base Moscovian Stage	311.7	1.1	"	Near lowest occurrences of Declinognathodus donetzianus and/or Idiognathoides postsulcatus conodont species, and fusulinid species Aljutovella aljutovica	-	Guide event is undecided. GSSP anticipated in 2008	-
*Lower Pennsylvanian Series*
base Bashkirian Stage, base Pennsylvanian Subsystem	318.1	1.3	"	Conodont, lowest occurrence of Declinognathodus nodiliferus s.l.	82.9 m above top of Battleship Wash Fm., Arrow Canyon, southern Nevada, USA	GSSP ratified 1996. Subsystem rank with Mississippian and Pennsylvanian names ratified 2000.	Episodes 22 (4), p.272-283, 1999
*Mississippian Subsystem*
*Upper Mississippian Series* (series classification approved in 2004)
base Serpukhovian	326.4	1.6	"	Near lowest occurrence of conodont, Lochriea crusiformis	-	Guide event is undecided. GSSP anticipated in 2007	-
*Middle Mississippian Series*
base Visean	345.3	2.1	"	Foraminifer, lineage Eoparastaffella simplex morphotype 1/morphotype 2	Leading candidate is Pengchong, south China	GSSP anticipated in 2006	-
*Lower Mississippian Series*
base Tournaisian, base Mississippian Subsystem, base Carboniferous System	359.2	2.5	"	Conodont, above lowest occurrence of Siphonodella sulcata	Base of Bed 89, La Serre, Montagne Noir, Cabrières, southern France	Ratified 1990	Episodes 14 (4), p.331-336, 1991
Devonian System
*Upper Devonian Series*
base Famennian Stage	374.5	2.6	Devonian time scale is a statistical fit of a composite biostratigraphic zonation (based on Figure 8 of Williams et al., 2000) to selected radiometric ages	Just above major extinction horizon (Upper Kellwasser Event), including conodonts Ancyrodella and Ozarkodina and goniatites of Gephuroceratidae and Beloceratidae	base of Bed 32a, upper Coumiac quarry, Cessenon, Montagne Noir, southern France	Ratified 1993	Episodes 16 (4), p.433-441, 1993
base Frasnian Stage	385.3	2.6	"	Conodont, lowest occurrence of Ancyrodella rotundiloba (defines base of Lower Polygnathus asymmetricus conodont Zone)	Base of Bed 42a', Col du Puech de la Suque section, St. Nazaire-de-Ladarez, SE Montagne Noir, southern France	Ratified 1986	Episodes 10 (2), p.97-101, 1987
*Middle Devonian Series*
base Givetian Stage	391.8	2.7	"	Conodont, lowest occurrence of Polygnathus hemiansatus, near base of goniatite Maenioceras Stufe	Base of Bed 123, Jebel Mech Irdane ridge, Tafilalt, Morocco	Ratified 1994	Episodes 18 (3), p.107-115, 1995
base Eifelian Stage	397.5	2.7	"	Conodont, lowest occurrence of Polygnathus costatus partitus; major faunal turnover	Base unit WP30, trench at Wetteldorf Richtschnitt, Schönecken-Wetteldorf, Eifel Hills, western Germany	Ratified 1985	Episodes 8 (2), p.104-109, 1985
*Lower Devonian Series*
base Emsian Stage	407.0	2.8	"	Conodont, lowest occurrence of Polygnathus kitabicus (= Po. dehiscens)	Base of Bed 9/5, Zinzil'ban Gorge, SE of Samarkand, Uzbekistan	Ratified 1995	Episodes 20 (4), p. 235-240, 1997
base Pragian Stage	411.2	2.8	"	Conodont, lowest occurrence of Eognathodus sulcatus	Base of Bed 12, Valká Chuchle quarry, southwest part of Prague city, Czech Republic	Ratified 1989	Episodes 12 (2), p.109-113, 1989
base Lochkovian Stage, base Devonian System	416.0	2.8	base-Devonian from scale in Cooper (GTS 2004), which is 1 myr younger than Tucker et al (1998) estimate.	Graptolite, lowest occurrence of Monograptus uniformis	Within Bed 20, Klonk, Barrandian area, southwest of Prague, Czech Republic	Ratified 1972	Martinsson (ed.), The Silurian-Devonian Boundary, IUGS Series A, no.5, 349 pp., 1977
Silurian System [Holland and Bassett (eds), A Global Standard for the Silurian System, Nat. Mus. Wales, Geol. Series No.10, Cardiff, 325 pp., 1989]
*Pridoli Series*
base Pridoli Series (not subdivided in stages)	418.7	2.7	Silurian and Ordovician time scales are from calibrating a CONOP composite graptolite zonation to selecte radiometric ages	Graptolite, lowest occurrence of Monograptus parultimus	Within Bed 96, Pozáry section near Reporje, Barrandian area, Prague, Czech Republic	Ratified 1984	Episodes 8 (2), p.101-103, 1985
*Ludlow Series*
base Ludfordian Stage	421.3	2.6	"	Imprecise. May be near base of Saetograptus leintwardinensis graptolite zone.	Base of lithological unit C, Sunnyhill Quarry, Ludlow, Shropshire, southwest England, UK	Ratified 1980	Lethaia 14, p.168, 1981; Episodes 5 (3), p.21-23, 1982
base Gorstian Stage	422.9	2.5	"	Imprecise. Just below base of local acritarch Leptobrachion longhopense range zone. May be near base of Neodiversograptus nilssoni graptolite zone	Base of lithological unit F, Pitch Coppice quarry, Ludlow, Shropshire, southwest England, UK	Ratified 1980	Lethaia 14, p.168, 1981; Episodes 5 (3), p.21-23, 1982
*Wenlock Series*
base Homerian Stage	426.2	2.4	"	Graptolite, lowest occurrence of Cyrtograptus lundgreni (defines base of C. lundgreni graptolite zone)	Graptolite biozone intersection in stream section in Whitwell Coppice, Homer, Shropshire, southwest England, UK	Ratified 1980	Lethaia 14, p.168, 1981; Episodes 5 (3), p.21-23, 1982
base Sheinwoodian Stage	428.2	2.3	"	Imprecise. Between the base of acritarch biozone 5 and extinction of conodont Pterospathodus amorphognathoides. However, the current GSSP does not coincide with the base of the Cyrtograptus centrifugus Biozone, as was supposed when the GSSP was define. Restudy has recommended a slightly higher and correlatable level on condonts -- the Ireviken datum 2, which coincides approximately with the base of the murchisoni graptolite biozone	Base of lithological unit G, Hughley Brook, Apedale, Shropshire, southwest England, UK	Ratified 1980	Lethaia 14, p.168, 1981; Episodes 5 (3), p.21-23, 1982
*Llandovery Series*
base Telychian Stage	436.0	1.9	"	Brachiopods, just above extinction of Eocoelia intermedia and below lowest succeeding species Eocoelia curtisi. Near base of Monograptus turriculatus graptolite zone.	Locality 162 in transect d, Cefn Cerig road, Llandovery area, south-central Wales, UK	Ratified 1984	Episodes 8 (2), p.101-103, 1985
base Aeronian Stage	439.0	1.8	"	Graptolite, lowest occurrence of Monograptus austerus sequens (defines base of Monograptus triangulatus graptolite zone)	Base of locality 72 in transect h, Trefawr forestry road, north of Cwm-coed-Aeron Farm, Llandovery area, south-central Wales, UK	Ratified 1984	Episodes 8 (2), p.101-103, 1985
base Rhuddanian Stage, base Silurian System	443.7	1.5	"	Graptolites, lowest occurrences of Akidograptus ascensus, with FAD of Parakidograptus acuminatus occurring slightly higher	1.6 m above base of Birkhill Shale Fm., Dob's Linn, Moffat, Scotland, UK	Ratified 1984	Episodes 8 (2), p.98-100, 1985
Ordovician System
*Upper Ordovician Series*
base Hirnantian Stage	445.6	1.5	"	Graptolite, lowest occurrence of Normalograptus extraordinarius, base of major positive carbon-13 isotope excursion, and beginning of pronounced sea-level fall associated with onset of a major glaciation	0.39 m below base of Kuanyinchiao Bed, Wangjiawan North section, 42 km N. of Yichang city (west Hubei province, China)	GSSP anticipated in 2005	-
base Katian Stage	455.8	1.6	"	Graptolite, lowest occurrence of Diplacanthograptus caudatus. Just below base of Guttenberg carbon-13 isotope excursion	4 m above base of Bigfort Chert, Black Knob Ridge section, 5 km NE of Atoka town (S. Oklahoma, USA)	GSSP anticipated in 2005	-
base Sandbian Stage	460.9	1.6	"	Graptolite, lowest occurrence of Nemagraptus gracilis	1.4 m below phosphorite in E14a outcrop, Fågelsång, Scane, southern Sweden	Ratified 2002	Episodes 23 (2), p.102-109, 2000 (proposal; formal GSSP publication in preparation).
*Middle Ordovician Series*
base Darriwillian Stage	468.1	1.6	"	Graptolite, lowest occurrence of Undulograptus austrodentatus	Base of Bed AEP184, 22 m below top of Ningkuo Fm., Huangnitang, Changshan, Zhejiang province, southeast China	Ratified 1987	Episodes 20 (3), p.158-166, 1997
base of third stage (not yet named)	471.8	1.6	"	Conodont, potentially lowest occurrence of Protoprioniodus aranda or of Baltoniodus triangularis	Candidate sections at Niquivil (Argentina) and Huanghuachang (China)	Guide event is undecided. GSSP anticipated in 2006	Proposal in Episodes 28 (2), p.105-117, 2005
*Lower Ordovician Series*
Base Floian Stage	478.6	1.7	"	Graptolite, lowest occurrence of Tetragraptus approximatus	Just above E bed, Diabasbrottet quarry, Västergötland, southern Sweden	Ratified 2002	Episodes 27 (4), p.265-272, 2004
base of Tremadocian stage, base Ordovician System	488.3	1.7	"	Conodont, lowest occurrence of Iapetognathus fluctivagus;just above base of Cordylodus lindstromi conodont Zone. Just below lowest occurrence of planktonic graptolites. Currently dated around 489 Ma	Within Bed 23 at the 101.8 m level, Green Point, western Newfoundland, Canada	Ratified 2000	Episodes 24 (1), p.19-28, 2001
Cambrian System
Overview of potential Cambrian subdivisions in Episodes 23 (3), p. 188-195, 2000
*Upper ("Furongian") Series*
Stage 10	-	-	-	Trilobite, lowest occurrence of Lotagnostus americanus. An internal substage division might be lowest occurrence of Codylodus adesei conodont	Candidate section is Duibian (Zhejiang province, China)	GSSP anticipated in 2008	-
Stage 9	-	-	-	Trilobite, lowest occurrence of Agnostotes orientalis	Candidate sections at Duibian (Zhejiang province, China) and Gonggiri (Korea)	GSSP anticipated in 2007	-
base Paibian Stage, base Furongian Series	501.0	2.0	Radiometric ages near primary marker level. Estimated age and uncertainty only	Trilobite, lowest occurrence of agnostoid Glyptagnostus reticulatus. Coincides with base of large positive carbon-isotope excursion	369.06 m above base of Huaqiao Fm, Paibi section, NW Hunan province, south China	Ratified 2003	Lethaia 37 (4), p.365-380, 2004
*Series 3*
Stage 7	-	-	-	Trilobite, lowest occurrence of Lejopyge laevigata	>Candidate sections are at Wangcun or nearby Luoyixi (NW Hunan province, S. China)	GSSP anticipated in 2007	-
Stage 6	-	-	-	Trilobite, lowest occurrence of Ptychagnostus atavus	Candidate section is Wangcun (NW Hunan province, S. China)	GSSP anticipated in 2006	-
Stage 5	513.0	2.0	Radiometric ages near primary marker level. Estimated age and uncertainty only	Trilobite, potentially lowest occurrence of Oryctocephalus indicus	Candidate sections are Wuliu-Zengjiayan (east Guizhou, China) and Split Mountain (Nevada, USA)	GSSP anticipated in 2007	-
*Series 2*
Stage 4	-	-	-	Trilobite, lowest occurrence of Olenellus or Redlichia	-	Guide event is undecided	-
Stage 3	-	-	-	Trilobites -- their lowest occurrence	-	-	-
*Lower Series*
Stage 2	-	-	-	Small Shelly Fossils, or Archaeocyathid species	-	Guide event is undecided	-
base Cambrian System, base Paleozoic Era, base Phanerozoic Eon	542.0	1.0	U-Pb age from Oman coinciding with the negative carbon excursion	Trace fossil, lowest occurrence of Treptichnus (Phycodes) pedum. Near base of negative carbon-isotope excursion	2.4 m above base of Member 2 of Chapel Island Fm., Fortune Head, Burin Peninsula, southeast Newfoundland, Canada	Ratified 1992	Episodes 17 (1&2), p.95-100, 1994.
PROTEROZOIC Eon
Pre-Cambrian eras and systems below Ediacaran are defined by absolute ages, rather than stratigraphic points.
Neoproterozoic Era
base Ediacaran System	630	-	Age suggested by Ediacaran Subcomm.; bracketed by radiometric ages of 600 and 635 Ma	Termination of Varanger (or Marinoan) glaciation.	"Base of the Marinoan cap carbonate (Nuccaleena Formation), immediately above the Elatina diamictite in the Enorama Creek section, Flinders Ranges, South Australia."	"Neoproterozoic III" (ratified 1990 with base defined chronometrically at 650 Ma) was formally replaced by Ediacaran Period and its GSSP in Feb 2004.	Summary in Science 305, p.621-622, 2004. Episodes article in preparation
Cryogenian System	850	-	Defined chronometrically; but will be replaced by GSSP	Base = 850 Ma	-	Ratified 1990. GSSP replacement planned for 2007	Episodes 14 (2), p.139-140, 1991
Tonian System	1000	-	Defined chronometrically	Base = 1000 Ma	-	Ratified 1990	Episodes 14 (2), p.139-140, 1991
Mesoproterozoic Era
Stenian System	1200	-	Defined chronometrically	Base = 1200 Ma	-	Ratified 1990	Episodes 14 (2), p.139-140, 1991
Ectasian System	1400	-	Defined chronometrically	Base = 1400 Ma	-	Ratified 1990	Episodes 14 (2), p.139-140, 1991
Calymmian System	1600	-	Defined chronometrically	Base = 1600 Ma	-	Ratified 1990	Episodes 14 (2), p.139-140, 1991
Paleoproterozoic Era
Statherian System	1800	-	Defined chronometrically	Base = 1800 Ma	-	Ratified 1990	Episodes 14 (2), p.139-140, 1991
Orosirian System	2050	-	Defined chronometrically	Base = 2050 Ma	-	Ratified 1990	Episodes 14 (2), p.139-140, 1991
Rhyacian System	2300	-	Defined chronometrically	Base = 2300 Ma	-	Ratified 1990	Episodes 14 (2), p.139-140, 1991
Siderian System	2500	-	Defined chronometrically; but will be replaced by GSSP	Base = 2500 Ma	-	Ratified 1990. GSSP replacement planned for 2007	Episodes 14 (2), p.139-140, 1991
ARCHEAN Eon
Neoarchean Era	2800	-	Defined chronometrically	Base = 2800 Ma	-	Subcomm. decision 1996, but not submitted to ICS	Informally in Episodes 15 (2), p.122-123, 1992.
Mesoarchean Era	3200	-	Defined chronometrically	Base = 3200 Ma	-	Subcomm. decision 1996, but not submitted to ICS	Informally in Episodes 15 (2), p.122-123, 1992.
Paleoarchean Era	3600	-	Defined chronometrically	Base = 3600 Ma	-	Subcomm. decision 1996, but not submitted to ICS	Informally in Episodes 15 (2), p.122-123, 1992.
Eoarchean Era	~4000	-	Base is not defined	Oldest preserved rocks on Earth's surface	-	Subcomm. decision 1996, but not submitted to ICS	Informally in Episodes 15 (2), p.122-123, 1992
HADIAN Eon	~4650	-	Base is not defined	Formation of planet Earth. Informal term	-	-	-

EON, Era, System, Series, Stages

Age (Ma)
GTS 2004

Est.
±Ma

Derivation of age

Principal correlative events

GSSP and location

Status

Publication

PHANEROZOIC Eon

Cenozoic Era

Neogene System

QUATERNARY Sub-System

2.588

Quaternary is a formal Sub-System (Sub-Era) of the Cenozoic time scale. It is the interval of oscillating climatic extremes (glacial and interglacial episodes) that was initiated at about 2.6 Ma (set equal to base of Gelasian stage), therefore it encompasses the Holocene and Pleistocene epochs and the late Pliocene.

Equivalent to GSSP of Gelasian at Monte San Nicola, Gela, Sicily, Italy. Correlates with Marine Isotopic stage 103, and base of magnetic polarity chronozone C2r (Matuyama)

ICS formal recommendation to INQUA and ICS; Sept 2005.

Proposal in Episodes 28 (2), p.118-120, 2005

Holocene Series

base Holocene

0.011784

0.00

Annual layer counting in ice core ("ka" is relative to AD2000); counting uncertainy is 69 years

End of the Younger Dryas cold spell, which is reflected in a shift in deuterium excess values, followed closely by changes in d18O, dust concentration, a range of chemical species, and by a change in annual layer thickness

NorthGRIP ice core, Greenland

GSSP anticipated in 2005

Pleistocene Series

base upper Pleistocene Subseries

0.126

0.00

Astronomical cycles in sediments

base of the Eemian interglacial stage (= base of marine isotope stage 5e) before final glacial episode of Pleistocene

Amsterdam-Terminal borehole (63.5 m below surface; 52°22'45"N; 4°54'52"E), Netherlands

GSSP anticipated in 2006

base middle Pleistocene Subseries

0.781

0.00

Astronomical cycles in sediments

Brunhes-Matuyama magnetic reversal

Candidate sections in Italy (Montalbano Jorica or Valle di Manche) and Japan (Chiba)

GSSP anticipated in 2007

base Pleistocene Series

1.806

0.00

Astronomical cycles in sediments

Just above top of magnetic polarity chronozone C2n (Olduvai) and the extinction level of calcareous nannofossil Discoaster brouweri (base Zone CN13). Above are lowest occurrence of calcareous nannofossil medium Gephyrocapsa spp. and extinction level of planktonic foraminifer Globigerinoides extremus.

Top of sapropel layer 'e', Vrica section, Calabria, Italy

Ratified 1985

Episodes 8 (2), p.116-120, 1985

Pliocene Series

base Gelasian Stage

2.588

0.00

Astronomical cycles in sediments

Isotopic stage 103, base of magnetic polarity chronozone C2r (Matuyama). Above are extinction levels of calcareous nannofossil Discoaster pentaradiatus and D. surculus (base Zone CN12c).

Midpoint of sapropelic Nicola Bed ("A5"), Monte San Nicola, Gela, Sicily, Italy

Ratified 1996

Episodes 21 (2), p.82-87, 1998

base Piacenzian Stage

3.600

0.00

Astronomical cycles in sediments

Base of magnetic polarity chronozone C2An (Gauss); extinction levels of planktonic foraminifers Globorotalia margaritae (base Zone PL3) and Pulleniatina primalis.

Base of beige layer of carbonate cycle 77, Punta Piccola, Sicily, Italy

Ratified 1997

Episodes 21 (2), p.88-93, 1998

base Zanclean Stage, base Pliocene Series

5.332

0.00

Astronomical cycles in sediments

Top of magnetic polarity chronozone C3r, ~100 kyr before Thvera normal-polarity subchronozone (C3n.4n). Calcareous nannofossils -- near extinction level of Triquetrorhabdulus rugosus (base Zone CN10b) and the lowest occurrence of Ceratolithus acutus.

Base of Trubi Fm (base of carbonate cycle 1), Eraclea Minoa, Sicily, Italy

Ratified 2000

Episodes 23 (3), p.179-187, 2000

Miocene Series

base Messinian Stage

7.246

0.00

Astronomical cycles in sediments

Astrochronology age of 7.251 Ma; middle of magnetic polarity chronozone C3Br.1r; lowest regular occurrence of the Globorotalia conomiozea planktonic foraminifer group.

Base of red layer of carbonate cycle 15, Oued Akrech, Rabat, Morocco

Ratified 2000

Episodes 23 (3), p. 172-178, 2000

base Tortonian Stage

11.608

0.00

Astronomical cycles in sediments

Last Common Occurrences of the calcareous nannofossil Discoaster kugleri and the planktonic foraminifer Globigerinoides subquadratus. Associated with the short normal-polarity subchron C5r.2n.

Midpoint of sapropel 76, Monte dei Corvi beach section, Ancona, Italy

Ratified 2003

Episodes 28 (1), p.6-17, 2005

base Serravallian Stage

13.65

0.00

Astronomical cycles in sediments

Near lowest occurrence of nannofossil Sphenolithus heteromorphus, within magnetic polarity chronozone C5ABr, and Mi3b isotopic event (global cooling episode)

Candidate on Malta (Ras il Pellegrin section) at base of Blue Clay

GSSP anticipated in 2006

base Langhian Stage

15.97

0.00

Calibrated magnetic anomaly scale

Near first occurrence of planktonic foraminifer Praeorbulina glomerosa and top of magnetic polarity chronozone C5Cn.1n

Potentially in astronomically-tuned ODP core (Leg 154) or in Italy (Moria or La Vedere)

GSSP anticipated in 2008

base Burdigalian Stage

20.43

0.00

Calibrated magnetic anomaly scale

Near lowest occurrence of planktonic foraminifer Globigerinoides altiaperturus or near top of magnetic polarity chronozone C6An

Potentially in astronomically-tuned ODP core

Guide event is undecided. GSSP anticipated in 2008

base Aquitanian Stage, base Miocene Series, base Neogene System

23.03

0.00

Astronomical cycles in sediments

Base of magnetic polarity chronozone C6Cn.2n; lowest occurrence of planktonic foraminifer Paragloborotalia kugleri; near extinction of calcareous nannofossil Reticulofenestra bisecta (base Zone NN1).

35 m from top of Lemme-Carrosio section, Carrosio village, north of Genoa, Italy

Ratified 1996

Episodes 20 (1),p. 23-28, 1997

Paleogene System

Oligocene Series

base Chattian Stage

28.4

0.1

Calibrated magnetic anomaly scale relative to base-Miocene and C24n. Arbitrary 100 kyr uncertainty assigned.

Potentially extinction of planktonic foraminifer Chiloguembelina (base Foram Zone P21b); or an isotopic/climatic event

Possibly Monte Cagnero (Umbria-Marche region, Italy)

GSSP anticipated in 2006

base Rupelian Stage, base Oligocene Series

33.9

0.1

Calibrated magnetic anomaly scale relative to base-Miocene and C24n.

Planktonic foraminifer, extinction of Hantkenina

Base of marl bed at 19m above base of Massignano quarry, Ancona, Italy

Ratified 1992

Episodes 16 (3), p.379-382, 1993

Eocene Series

base Priabonian Stage

37.2

0.1

Calibrated magnetic anomaly scale relative to base-Miocene and C24n

Near lowest occurrence of calcareous nannofossil Chiasmolithus oamaruensis (base Zone NP18)

Tiziano Bed, Alano section (Piave River; Veneto Prealps, Belluno province, N. Italy)

GSSP anticipated in 2006

base Bartonian Stage

40.4

0.2

Calibrated magnetic anomaly scale relative to base-Miocene and C24n

Near extinction of calcareous nannofossil Reticulofenestra reticulata

GSSP anticipated in 2008

base Lutetian Stage

48.6

0.2

Calibrated magnetic anomaly scale relative to base-Miocene and C24n

Planktonic foraminifer, lowest occurrence of Hantkenina

Leading candidate is Agost section, Murcia province, Betic Cordilleras, Spain

GSSP anticipated in 2007

base Ypresian Stage, base Eocene Series

55.8

0.2

Astronomical cycles in sediments scaled from base-Paleocene

Base of negative carbon-isotope excursion

Dababiya Section near Luxor, Egypt

Ratified 2003

Micropaleontology v.49 (Suppl. 1), 2003. Episodes article in preparation

Paleocene Series

base Thanetian Stage

58.7

0.2

Astronomical cycles in sediments scaled from base Paleocene, using base of magnetic polarity chronozone C26n. Arbitrary 0.1 (2 precession cycles, plus the base-Paleogene radiometric) uncertainty assigned to all estimates.

Magnetic polarity chronozone, base of C26n

Leading candidate is Zumaya section, northern Spain

GSSP anticipated in 2007

base Selandian Stage

61.7

0.2

Astronomical cycles in sediments scaled from base Paleocene, using magnetic polarity chronozone placement of C27n.9

Undecided; possibilities include top or bottom of Foram Zone P3a, or C-13 excursion near base of calcareous nannofossil Zone NP5 (which would be ~1 myr younger than age estimate shown here)

Leading candidate is Zumaya section, northern Spain

Guide event is undecided. GSSP anticipated in 2007

base Danian Stage, base Paleogene System, base Cenozoic

65.5

0.3

Ar-Ar and U-Pb age agreement

Iridium geochemical anomaly. Associated with a major extinction horizon (foraminifers, calcareous nannofossils, dinosaurs, etc.);

Base of boundary clay, El Kef, Tunisia (but deterioration may require assigning a replacement section)

Ratified 1991

Mesozoic Era

Cretaceous System

Most Cretaceous substages also have recommended GSSP criteria

Upper Cretaceous Series

base Maastrichtian Stage

70.6

0.6

Estimated placement relative to Ar-Ar calibrated Sr-curve

Mean of 12 biostratigraphic criteria of equal importance. Closely above is lowest occurrence of ammonite Pachydiscus neubergicus. Boreal proxy is lowest occurrence of belemnite Belemnella lanceolata.

115.2 m level in Grande Carrière quarry, Tercis-les-Bains, Landes province, SW France

Ratified 2001

Episodes 24 (4), p.229-238, 2001; Odin (ed.) IUGS Spec. Publ. Series, v.36, Elsevier, 910pp.

base Campanian Stage

83.5

0.7

Spline fit of Ar-Ar ages and ammonite zones.

Crinoid, extinction of Marsupites testudinarius

Leading candidates are in southern England and in Texas

GSSP anticipated in 2008

base Santonian Stage

85.8

0.7

Spline fit of Ar-Ar ages and ammonite zones.

Inoceramid bivalve, lowest occurrence of Cladoceramus undulatoplicatus

Leading candidates are in Spain, England and Texas

GSSP anticipated in 2007

base Coniacian Stage

89.3

1.0

Spline fit of Ar-Ar ages and ammonite zones.

Inoceramid bivalve, lowest occurrence of Cremnoceramus rotundatus (sensu Tröger non Fiege)

Base of Bed MK47, Salzgitter-Salder Quarry, SW of Hannover, Lower Saxony, northern Germany

GSSP anticipated in 2006

base Turonian Stage

93.5

0.8

Spline fit of Ar-Ar ages and ammonite zones

Ammonite, lowest occurrence of Watinoceras devonense

Base of Bed 120, Rock Canyon Anticline, east of Pueblo, Colorado, west-central USA

Ratified 2003

Episodes 28(1), p. 93-104, 2005

base Cenomanian Stage

99.6

0.9

Spline fit of Ar-Ar ages and ammonite zones, plus monitor standard correction. Then cycle stratigraphy to place foraminifer datum relative to ammonite zonation.

Planktonic foraminifer, lowest occurrence of Rotalipora globotruncanoides

36 m below top of Marnes Bleues Formation, Mont Risou, Rosans, Haute-Alpes, SE France

Ratified 2002

Episodes 27 (1), p.21-32, 2004

Lower Cretaceous Series

base Albian Stage

112.0

1.0

Cycle-stratigraphy of FAD of P. columnata relative to base of Cenomanian, with large uncertainty due to lack of GSSP criteria

Candidates include: (1) calcareous nannofossil, lowest occurrence of Praediscosphaera columnata (= P. cretacea of some earlier studies), (2) carbon-isotope excursion (black-shale episode), (3) ammonite

Guide event is undecided. GSSP anticipated in 2008

base Aptian Stage

125.0

1.0

Base of M0r, as recomputed from Ar-Ar age from MIT guyot

Magnetic polarity chronozone, base of M0r; near base of Paradeshayesites oglanlensis ammonite zone

Leading candidate is Gorgo a Cerbara, Piobbico, Umbria-Marche, central Italy

GSSP anticipated in 2006

base Barremian Stage

130.0

1.5

Pacific spreading model for magnetic anomaly ages (variable rate), using placement at M5n.8.

Ammonite, lowest occurrence of Spitidiscus hugii – Spitidiscus vandeckii group

Leading candidate is Río Argos near Caravaca, Murcia province, Spain

GSSP anticipated in 2006

base Hauterivian Stage

136.4

2.0

Pacific spreading model for magnetic anomaly ages (variable rate), using placement at base M11n

Ammonite, lowest occurrence of genus Acanthodiscus (especially A. radiatus)

Leading candidate is La Charce village, Drôme province, southeast France

GSSP anticipated in 2006

base Valanginian Stage

140.2

3.0

Pacific spreading model for magnetic anomaly ages (variable rate), using placement at M14r.3 (base T. pertransiens).

Calpionellid, lowest occurrence of Calpionellites darderi (base of Calpionellid Zone E); followed by the lowest occurrence of ammonite “Thurmanniceras” pertransiens

Leading candidates are near Montbrun-les-Bains (Drôme province, SE France) and Cañada Luenga (Betic Cordillera, S. Spain)

GSSP anticipated in 2007

base Berriasian Stage, base Cretaceous System

145.5

4.0

Pacific spreading model for magnetic anomaly ages (variable rate), assigning to base of Berriasella jacobi zone (M19n.2n.55)

Maybe near lowest occurrence of ammonite Berriasella jacobi

Guide event is undecided. GSSP anticipated in 2008

Jurassic System

Upper Jurassic Series

base Tithonian Stage

150.8

4.0

Pacific spreading model for magnetic anomaly ages (variable rate), assigning to base M22An

Near base of Hybonoticeras hybonotum ammonite zone and lowest occurrence of Gravesia genus, and the base of magnetic polarity chronozone M22An

Candidates are Mt. Crussol or Canjuers (SE France) and Fornazzo (Sicily, S. Italy)

Guide event is undecided. GSSP anticipated in 2007

base Kimmeridgian Stage

155.7

4.0

Pacific spreading model for magnetic anomaly ages (variable rate), assigning to base M26r.2 (Boreal ammonite definition)

Ammonite, near base of Pictonia baylei ammonite zone of Boreal realm

Candidate is Flodigarry (Isle of Skye, NW Scotland)

GSSP anticipated in 2006

base Oxfordian Stage

161.2

4.0

Pacific spreading model for magnetic anomaly ages (variable rate), assigning to base M36An

Ammonite, Brightia thuouxensis Horizon at base of the Cardioceras scarburgense Subzone (Quenstedtoceras mariae Zone)

Leading candidates are Savouron (Provence province, SE France) and Redcliffe Point (Dorset, SW England)

GSSP anticipated in 2006

Middle Jurassic Series

base Callovian Stage

164.7

4.0

Equal subzones scale Bajo-Bath-Callov

Ammonite, lowest occurrence of the genus Kepplerites (Kosmoceratidae) (defines base of Macrocephalites herveyi Zone in sub-Boreal province of Great Britain to southwest Germany)

Leading candidate is Pfeffingen, Swabian Alb, SW Germany

GSSP anticipated in 2006

base Bathonian Stage

167.7

3.5

Equal subzones scale Bajo-Bath-Callov

Ammonite, lowest occurrence of Parkinsonia (G.) convergens (defines base of Zigzagiceras zigzag Zone)

Candidates are in Iberia, and near Digne (SE France)

GSSP anticipated in 2007

base Bajocian Stage

171.6

3.0

Equal subzones scale Bajo-Bath-Callov

Ammonite, lowest occurrence of the genus Hyperlioceras (defines base of the Hyperlioceras discites Zone)

Base of Bed AB11, 77.8 m above base of Murtinheira section, Cabo Mondego, western Portugal

Ratified 1996

Episodes 20 (1), p.16-22, 1997

base Aalenian Stage

175.6

2.0

Duration of Aalenian-Toarcian from cycle stratigraphy

Ammonite, lowest occurrence of Leioceras genus

base of Bed FZ107, Fuentelsalz, central Spain

Ratified 2000

Episodes 24 (3), p.166-175, 2001

Lower Jurassic Series

base Toarcian Stage

183.0

1.5

Duration of Aalenian-Toarcian from cycle stratigraphy

Ammonite, near lowest occurrence of a diversified Eodactylites ammonite fauna; correlates with the NW European Paltus horizon.

Peniche (Portugal)

GSSP anticipated in 2006

base Pliensbachian Stage

189.6

1.5

Cycle-scaled linear Sr trend

Ammonite, lowest occurrences of Bifericeras donovani and of genera Apoderoceras ((defines base of Phricodoceras taylori subzone of Uptonia jamesoni ammonite zone)

Base of Bed 73b, Wine Haven section, Robin Hood's Bay, Yorkshire, England, UK

Ratified 2005

Proposal in Eclogae Geol. Helv. 96, p.275-297, 2003. Episodes article in preparation

base Sinemurian Stage

196.5

1.0

Cycle-scaled linear Sr trend

Ammonite, lowest occurrence of arietitid genera Vermiceras and Metophioceras

0.9 m above base of Bed 145, East Quantoxhead, Watchet, West Somerset, SW England, UK

Ratified 2000

Episodes 25 (1), p. 22-26, 2002

base Hettangian Stage, base Jurassic System

199.6

0.6

U-Pb age just below proposed GSSP for base-Jurassic

Near lowest occurrence of smooth Psiloceras planorbis ammonite group

Guide event is undecided. GSSP anticipated in 2007

Triassic System

Upper Triassic Series

base Rhaetian Stage

203.6

1.5

Magnetostratigraphic correlation to cycle-scaled Newark magnetic polarity pattern

Near lowest occurrence of ammonite Cochlocera, conodonts Misikella spp. and Epigondolella mosheri, and radiolarian Proparvicingula moniliformis

Key sections in Austria, British Columbia (Canada), and Turkey

Guide event is undecided. GSSP anticipated in 2008

base Norian Stage

216.5

2.0

Magnetostratigraphic correlation to cycle-scaled Newark magnetic polarity pattern

Base of Klamathites macrolobatus or Stikinoceras kerri ammonoid zones and the Metapolygnathus communisti or M. primitius conodont zones

Leading candidates are in British Columbia (Canada), Sicily (Italy), and possibly Slovakia, Turkey (Antalya Taurus) and Oman.

Guide event is undecided. GSSP anticipated in 2008

base Carnian Stage

228.0

2.0

Magnetostratigraphic correlation to cycle-scaled Newark magnetic polarity pattern

Near first occurrence of the ammonoids Daxatina or Trachyceras, and of the conodont Metapolygnathus polygnathiformis

Candidate section at Prati di Stuores, Dolomites, northern Italy. Important reference sections in Spiti (India) and New Pass, Nevada (USA).

Guide event is undecided. GSSP anticipated in 2007

Middle Triassic Series

base Ladinian Stage

237.0

2.0

U-Pb array by Mundil et al. on levels near Nevadites (= Secedensis) ammonite zone in Dolomites, plus placement relative to magnetostratigraphy corrlations to cycle-scaled Newark magnetic polarity pattern

Ammonoid, lowest occurrence of the Eoprotrachyceras curionii (base of the E. curionii zone; onset of the Trachyceratidae family. Above lowest Neogondolella praehungarica conodont

Top of "Chiesense groove", 5m above base of Buchenstein Beds, Caffaro river bed, Bagolino (Brescia province, N. Italy)

Ratified 2005

Episodes article in preparation

base Anisian Stage

245.0

1.5

Proportional subzonal scaling

Conodont, lowest occurrences of Chiosella timorensis

Candidate section at Desli Caira (Dobrogea, Romania); significant sections in Guizhou Province (China) and South Primorye (Russia)

GSSP anticipated in 2007

Lower Triassic Series

base Olenekian Stage

249.7

0.7

Composite standard from conodonts scaled to base-Anisian and base-Triassic

Conodont, lowest occurrence of Neospathodus waageni; near lowest occurrence of Flemingites and Euflemingites ammonite genera

Chaohu (Anhui province, E. China). Important sections in Spiti

GSSP anticipated in 2006

base Induan Stage, base Triassic System, base Mesozoic

251.0

0.4

U-Pb ages bracket GSSP (Bowring et al., 1998)

Conodont, lowest occurrence of Hindeodus parvus; termination of major negative carbon-isotope excursion. About 1 myr after peak of Late Permian extinctions.

Base of Bed 27c, Meishan, Zhejiang, China

Ratified 2001

Episodes 24 (2), p.102-114, 2001

Paleozoic Era

Permian System

Lopingian Series

base Changhsingian Stage

253.8

0.7

Permian-Carboniferous time scale is derived from calibrating a master composite section to selected radiometric ages

Conodont, near lowest occurrence of conodont Clarkina wangi

Base of Bed 4a-2, 88 cm above base of Changxing Limestone, Meishan D section (Zhejiang province, E. China)

Ratified 2005

Episodes article in preparation

base Wuchiapingian Stage

260.4

0.7

Conodont, lowest occurrence of Clarkina postbitteri postbitteri

Ratified 2004

Episodes article in preparation

Guadalupian Series

base Capitanian Stage

265.8

0.7

Conodont, lowest occurrence of Jinogondolella postserrata

4.5 m above base of Pinery Limestone Member, Nipple Hill, SE Guadalupe Mountains, Texas, USA

Ratified 2001

Episodes article in preparation

base Wordian Stage

268.0

0.7

Conodont, lowest occurrence of Jinogondolella aserrata

7.6 m above base of Getaway Ledge outcrop, Guadalupe Pass, SE Guadalupe Mountains, Texas, USA

Ratified 2001

Episodes article in preparation

base Roadian Stage

270.6

0.7

Conodont, lowest occurrence of Jinogondolella nanginkensis

42.7 m above base of Cutoff Formation, Stratotype Canyon, southern Guadalupe Mountains, Texas, USA

Ratified 2001

Episodes article in preparation

Cisuralian Series

base Kungurian Stage

275.6

0.7

Near lowest occurrence of conodont Neostreptognathus pnevi - N. exculptus

Leading candidates are in southern Ural Mtns.

GSSP anticipated in 2007

base Artinskian Stage

284.4

0.7

Conodont, lowest occurrence of conodont Sweetognathus whitei

Leading candidates are in southern Ural Mtns.

GSSP anticipated in 2007

base Sakmarian Stage

294.6

0.8

Conodont, near lowest occurrence of conodont Sweetognathus merrelli

Leading candidate is at Kondurovsky, Orenburg Province, Russia.

GSSP anticipated in 2006

base Asselian Stage, base Cisuralian Series, base Permian System

299.0

0.8

Conodont, lowest occurrence of Streptognathodus isolatus within the S. "wabaunsensis" conodont chronocline. 6 m higher is lowest fusilinid foraminifer Sphaeroschwagerina vulgaris aktjubensis

27 m above base of Bed 19, Aidaralash Creek, Aktöbe, southern Ural Mountains, northern Kazakhstan

Ratified, 1996

Episodes 21 (1), p.11-18, 1998

Carboniferous System

Pennsylvanian Subsystem (series classification approved in 2004)

Upper Pennsylvanian Series

base Gzhelian Stage

303.9

0.9

Near lowest occurrences of the fusulinids Daixina, Jigulites and Rugosofusulina, or lowest occurrence of conodont Idiognathodus simulator (s.str.). Close to lowest occurrence of ammonoid Shumardites.

Guide event is undecided. GSSP anticipated in 2007

base Kasimovian Stage

306.5

1.0

Near base of Obsoletes obsoletes and Protriticites pseudomontiparus fusulinid zone, or lowest occurrence of Parashumardites ammonoid

Guide event is undecided. GSSP anticipated in 2008

Middle Pennsylvanian Series

base Moscovian Stage

311.7

1.1

Near lowest occurrences of Declinognathodus donetzianus and/or Idiognathoides postsulcatus conodont species, and fusulinid species Aljutovella aljutovica

Guide event is undecided. GSSP anticipated in 2008

Lower Pennsylvanian Series

base Bashkirian Stage, base Pennsylvanian Subsystem

318.1

1.3

Conodont, lowest occurrence of Declinognathodus nodiliferus s.l.

82.9 m above top of Battleship Wash Fm., Arrow Canyon, southern Nevada, USA

GSSP ratified 1996. Subsystem rank with Mississippian and Pennsylvanian names ratified 2000.

Episodes 22 (4), p.272-283, 1999

Mississippian Subsystem

Upper Mississippian Series (series classification approved in 2004)

base Serpukhovian

326.4

1.6

Near lowest occurrence of conodont, Lochriea crusiformis

Guide event is undecided. GSSP anticipated in 2007

Middle Mississippian Series

base Visean

345.3

2.1

Foraminifer, lineage Eoparastaffella simplex morphotype 1/morphotype 2

Leading candidate is Pengchong, south China

GSSP anticipated in 2006

Lower Mississippian Series

base Tournaisian, base Mississippian Subsystem, base Carboniferous System

359.2

2.5

Conodont, above lowest occurrence of Siphonodella sulcata

Base of Bed 89, La Serre, Montagne Noir, Cabrières, southern France

Ratified 1990

Episodes 14 (4), p.331-336, 1991

Devonian System

Upper Devonian Series

base Famennian Stage

374.5

2.6

Devonian time scale is a statistical fit of a composite biostratigraphic zonation (based on Figure 8 of Williams et al., 2000) to selected radiometric ages

Just above major extinction horizon (Upper Kellwasser Event), including conodonts Ancyrodella and Ozarkodina and goniatites of Gephuroceratidae and Beloceratidae

base of Bed 32a, upper Coumiac quarry, Cessenon, Montagne Noir, southern France

Ratified 1993

Episodes 16 (4), p.433-441, 1993

base Frasnian Stage

385.3

2.6

Conodont, lowest occurrence of Ancyrodella rotundiloba (defines base of Lower Polygnathus asymmetricus conodont Zone)

Base of Bed 42a', Col du Puech de la Suque section, St. Nazaire-de-Ladarez, SE Montagne Noir, southern France

Ratified 1986

Episodes 10 (2), p.97-101, 1987

Middle Devonian Series

base Givetian Stage

391.8

2.7

Conodont, lowest occurrence of Polygnathus hemiansatus, near base of goniatite Maenioceras Stufe

Base of Bed 123, Jebel Mech Irdane ridge, Tafilalt, Morocco

Ratified 1994

Episodes 18 (3), p.107-115, 1995

base Eifelian Stage

397.5

2.7

Conodont, lowest occurrence of Polygnathus costatus partitus; major faunal turnover

Base unit WP30, trench at Wetteldorf Richtschnitt, Schönecken-Wetteldorf, Eifel Hills, western Germany

Ratified 1985

Episodes 8 (2), p.104-109, 1985

Lower Devonian Series

base Emsian Stage

407.0

2.8

Conodont, lowest occurrence of Polygnathus kitabicus (= Po. dehiscens)

Base of Bed 9/5, Zinzil'ban Gorge, SE of Samarkand, Uzbekistan

Ratified 1995

Episodes 20 (4), p. 235-240, 1997

base Pragian Stage

411.2

2.8

Conodont, lowest occurrence of Eognathodus sulcatus

Base of Bed 12, Valká Chuchle quarry, southwest part of Prague city, Czech Republic

Ratified 1989

Episodes 12 (2), p.109-113, 1989

base Lochkovian Stage, base Devonian System

416.0

2.8

base-Devonian from scale in Cooper (GTS 2004), which is 1 myr younger than Tucker et al (1998) estimate.

Graptolite, lowest occurrence of Monograptus uniformis

Within Bed 20, Klonk, Barrandian area, southwest of Prague, Czech Republic

Ratified 1972

Martinsson (ed.), The Silurian-Devonian Boundary, IUGS Series A, no.5, 349 pp., 1977

Silurian System [Holland and Bassett (eds), A Global Standard for the Silurian System, Nat. Mus. Wales, Geol. Series No.10, Cardiff, 325 pp., 1989]

Pridoli Series

base Pridoli Series (not subdivided in stages)

418.7

2.7

Silurian and Ordovician time scales are from calibrating a CONOP composite graptolite zonation to selecte radiometric ages

Graptolite, lowest occurrence of Monograptus parultimus

Within Bed 96, Pozáry section near Reporje, Barrandian area, Prague, Czech Republic

Ratified 1984

Episodes 8 (2), p.101-103, 1985

Ludlow Series

base Ludfordian Stage

421.3

2.6

Imprecise. May be near base of Saetograptus leintwardinensis graptolite zone.

Base of lithological unit C, Sunnyhill Quarry, Ludlow, Shropshire, southwest England, UK

Ratified 1980

Lethaia 14, p.168, 1981; Episodes 5 (3), p.21-23, 1982

base Gorstian Stage

422.9

2.5

Imprecise. Just below base of local acritarch Leptobrachion longhopense range zone. May be near base of Neodiversograptus nilssoni graptolite zone

Base of lithological unit F, Pitch Coppice quarry, Ludlow, Shropshire, southwest England, UK

Ratified 1980

Lethaia 14, p.168, 1981; Episodes 5 (3), p.21-23, 1982

Wenlock Series

base Homerian Stage

426.2

2.4

Graptolite, lowest occurrence of Cyrtograptus lundgreni (defines base of C. lundgreni graptolite zone)

Graptolite biozone intersection in stream section in Whitwell Coppice, Homer, Shropshire, southwest England, UK

Ratified 1980

Lethaia 14, p.168, 1981; Episodes 5 (3), p.21-23, 1982

base Sheinwoodian Stage

428.2

2.3

Imprecise. Between the base of acritarch biozone 5 and extinction of conodont Pterospathodus amorphognathoides. However, the current GSSP does not coincide with the base of the Cyrtograptus centrifugus Biozone, as was supposed when the GSSP was define. Restudy has recommended a slightly higher and correlatable level on condonts -- the Ireviken datum 2, which coincides approximately with the base of the murchisoni graptolite biozone

Base of lithological unit G, Hughley Brook, Apedale, Shropshire, southwest England, UK

Ratified 1980

Lethaia 14, p.168, 1981; Episodes 5 (3), p.21-23, 1982

Llandovery Series

base Telychian Stage

436.0

1.9

Brachiopods, just above extinction of Eocoelia intermedia and below lowest succeeding species Eocoelia curtisi. Near base of Monograptus turriculatus graptolite zone.

Locality 162 in transect d, Cefn Cerig road, Llandovery area, south-central Wales, UK

Ratified 1984

Episodes 8 (2), p.101-103, 1985

base Aeronian Stage

439.0

1.8

Graptolite, lowest occurrence of Monograptus austerus sequens (defines base of Monograptus triangulatus graptolite zone)

Base of locality 72 in transect h, Trefawr forestry road, north of Cwm-coed-Aeron Farm, Llandovery area, south-central Wales, UK

Ratified 1984

Episodes 8 (2), p.101-103, 1985

base Rhuddanian Stage, base Silurian System

443.7

1.5

Graptolites, lowest occurrences of Akidograptus ascensus, with FAD of Parakidograptus acuminatus occurring slightly higher

1.6 m above base of Birkhill Shale Fm., Dob's Linn, Moffat, Scotland, UK

Ratified 1984

Episodes 8 (2), p.98-100, 1985

Ordovician System

Upper Ordovician Series

base Hirnantian Stage

445.6

1.5

Graptolite, lowest occurrence of Normalograptus extraordinarius, base of major positive carbon-13 isotope excursion, and beginning of pronounced sea-level fall associated with onset of a major glaciation

0.39 m below base of Kuanyinchiao Bed, Wangjiawan North section, 42 km N. of Yichang city (west Hubei province, China)

GSSP anticipated in 2005

base Katian Stage

455.8

1.6

Graptolite, lowest occurrence of Diplacanthograptus caudatus. Just below base of Guttenberg carbon-13 isotope excursion

4 m above base of Bigfort Chert, Black Knob Ridge section, 5 km NE of Atoka town (S. Oklahoma, USA)

GSSP anticipated in 2005

base Sandbian Stage

460.9

1.6

Graptolite, lowest occurrence of Nemagraptus gracilis

1.4 m below phosphorite in E14a outcrop, Fågelsång, Scane, southern Sweden

Ratified 2002

Episodes 23 (2), p.102-109, 2000 (proposal; formal GSSP publication in preparation).

Middle Ordovician Series

base Darriwillian Stage

468.1

1.6

Graptolite, lowest occurrence of Undulograptus austrodentatus

Base of Bed AEP184, 22 m below top of Ningkuo Fm., Huangnitang, Changshan, Zhejiang province, southeast China

Ratified 1987

Episodes 20 (3), p.158-166, 1997

base of third stage (not yet named)

471.8

1.6

Conodont, potentially lowest occurrence of Protoprioniodus aranda or of Baltoniodus triangularis

Candidate sections at Niquivil (Argentina) and Huanghuachang (China)

Guide event is undecided. GSSP anticipated in 2006

Proposal in Episodes 28 (2), p.105-117, 2005

Lower Ordovician Series

Base Floian Stage

478.6

1.7

Graptolite, lowest occurrence of Tetragraptus approximatus

Just above E bed, Diabasbrottet quarry, Västergötland, southern Sweden

Ratified 2002

Episodes 27 (4), p.265-272, 2004

base of Tremadocian stage, base Ordovician System

488.3

1.7

Conodont, lowest occurrence of Iapetognathus fluctivagus;just above base of Cordylodus lindstromi conodont Zone. Just below lowest occurrence of planktonic graptolites. Currently dated around 489 Ma

Within Bed 23 at the 101.8 m level, Green Point, western Newfoundland, Canada

Ratified 2000

Episodes 24 (1), p.19-28, 2001

Cambrian System

Overview of potential Cambrian subdivisions in Episodes 23 (3), p. 188-195, 2000

Upper ("Furongian") Series

Stage 10

Trilobite, lowest occurrence of Lotagnostus americanus. An internal substage division might be lowest occurrence of Codylodus adesei conodont

Candidate section is Duibian (Zhejiang province, China)

GSSP anticipated in 2008

Stage 9

Trilobite, lowest occurrence of Agnostotes orientalis

Candidate sections at Duibian (Zhejiang province, China) and Gonggiri (Korea)

GSSP anticipated in 2007

base Paibian Stage, base Furongian Series

501.0

2.0

Radiometric ages near primary marker level. Estimated age and uncertainty only

Trilobite, lowest occurrence of agnostoid Glyptagnostus reticulatus. Coincides with base of large positive carbon-isotope excursion

369.06 m above base of Huaqiao Fm, Paibi section, NW Hunan province, south China

Ratified 2003

Lethaia 37 (4), p.365-380, 2004

Series 3

Stage 7

Trilobite, lowest occurrence of Lejopyge laevigata

>Candidate sections are at Wangcun or nearby Luoyixi (NW Hunan province, S. China)

GSSP anticipated in 2007

Stage 6

Trilobite, lowest occurrence of Ptychagnostus atavus

Candidate section is Wangcun (NW Hunan province, S. China)

GSSP anticipated in 2006

Stage 5

513.0

2.0

Radiometric ages near primary marker level. Estimated age and uncertainty only

Trilobite, potentially lowest occurrence of Oryctocephalus indicus

Candidate sections are Wuliu-Zengjiayan (east Guizhou, China) and Split Mountain (Nevada, USA)

GSSP anticipated in 2007

Series 2

Stage 4

Trilobite, lowest occurrence of Olenellus or Redlichia

Guide event is undecided

Stage 3

Trilobites -- their lowest occurrence

Lower Series

Stage 2

Small Shelly Fossils, or Archaeocyathid species

Guide event is undecided

base Cambrian System, base Paleozoic Era, base Phanerozoic Eon

542.0

1.0

U-Pb age from Oman coinciding with the negative carbon excursion

Trace fossil, lowest occurrence of Treptichnus (Phycodes) pedum. Near base of negative carbon-isotope excursion

2.4 m above base of Member 2 of Chapel Island Fm., Fortune Head, Burin Peninsula, southeast Newfoundland, Canada

Ratified 1992

Episodes 17 (1&2), p.95-100, 1994.

PROTEROZOIC Eon

Pre-Cambrian eras and systems below Ediacaran are defined by absolute ages, rather than stratigraphic points.

Neoproterozoic Era

base Ediacaran System

630

Age suggested by Ediacaran Subcomm.; bracketed by radiometric ages of 600 and 635 Ma

Termination of Varanger (or Marinoan) glaciation.

"Base of the Marinoan cap carbonate (Nuccaleena Formation), immediately above the Elatina diamictite in the Enorama Creek section, Flinders Ranges, South Australia."

"Neoproterozoic III" (ratified 1990 with base defined chronometrically at 650 Ma) was formally replaced by Ediacaran Period and its GSSP in Feb 2004.

Summary in Science 305, p.621-622, 2004. Episodes article in preparation

Cryogenian System

850

Defined chronometrically; but will be replaced by GSSP

Base = 850 Ma

Ratified 1990. GSSP replacement planned for 2007

Episodes 14 (2), p.139-140, 1991

Tonian System

1000

Defined chronometrically

Base = 1000 Ma

Ratified 1990

Episodes 14 (2), p.139-140, 1991

Mesoproterozoic Era

Stenian System

1200

Defined chronometrically

Base = 1200 Ma

Ratified 1990

Episodes 14 (2), p.139-140, 1991

Ectasian System

1400

Defined chronometrically

Base = 1400 Ma

Ratified 1990

Episodes 14 (2), p.139-140, 1991

Calymmian System

1600

Defined chronometrically

Base = 1600 Ma

Ratified 1990

Episodes 14 (2), p.139-140, 1991

Paleoproterozoic Era

Statherian System

1800

Defined chronometrically

Base = 1800 Ma

Ratified 1990

Episodes 14 (2), p.139-140, 1991

Orosirian System

2050

Defined chronometrically

Base = 2050 Ma

Ratified 1990

Episodes 14 (2), p.139-140, 1991

Rhyacian System

2300

Defined chronometrically

Base = 2300 Ma

Ratified 1990

Episodes 14 (2), p.139-140, 1991

Siderian System

2500

Defined chronometrically; but will be replaced by GSSP

Base = 2500 Ma

Ratified 1990. GSSP replacement planned for 2007

Episodes 14 (2), p.139-140, 1991

ARCHEAN Eon

Neoarchean Era

2800

Defined chronometrically

Base = 2800 Ma

Subcomm. decision 1996, but not submitted to ICS

Informally in Episodes 15 (2), p.122-123, 1992.

Mesoarchean Era

3200

Defined chronometrically

Base = 3200 Ma

Subcomm. decision 1996, but not submitted to ICS

Informally in Episodes 15 (2), p.122-123, 1992.

Paleoarchean Era

3600

Defined chronometrically

Base = 3600 Ma

Subcomm. decision 1996, but not submitted to ICS

Informally in Episodes 15 (2), p.122-123, 1992.

Eoarchean Era

~4000

Base is not defined

Oldest preserved rocks on Earth's surface

Subcomm. decision 1996, but not submitted to ICS

Informally in Episodes 15 (2), p.122-123, 1992

HADIAN Eon

~4650

Base is not defined

Formation of planet Earth. Informal term

Jun	JUL	Sep
	16
2005	2006	2007

Overview of Global Boundary Stratotype Sections and Points (GSSP's)