Ediacaran GSSP - closeup
Many GSSPs are marked by golden spikes. This 'golden spike' marks the GSSP for the start of the Ediacaran.

A GSSP, more fully a Global Boundary Stratotype Section and Point, is an internationally agreed point which defines the start of a stage on the geologic time scale.

The work is done by the International Commission on Stratigraphy, a part of the International Union of Geological Sciences. As of 2012, 64 of the 101 stages that need a GSSP have been decided.

Rules for GSSP

A geologic section has to follow the rules to be adapted as a GSSP by the ICS. The list below are the rules:

  • A GSSP has to decide the lower boundary (start of a geological period) of a geologic stage.
  • The lower boundary (start of a geological period) has to be decided using a primary (main) marker (usually first appearance datum of a fossil specie).
    • There should also be secondary markers (other fossils, chemical, geomagnetic reversal).
    • The horizon in which the marker appears should have minerals that can be radiometrically dated.
    • The marker has to have regional and global correlation in outcrops of the same age
    • The marker should be independent of facies.
  • The outcrop has to have an acceptable thickness
  • Sedimentation has to be constant without any changes in facies
  • The outcrop should not be affected by tectonic and sedimentary movements, and metamorphism
  • The outcrop has to be accessible to research and free to access.
    • This includes that the outcrop has to be located where it can be visited quickly (International airport and good roads), has to 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.


This list shows some of the GSSPs.

Period Epoch Age (mya) Status GSSP location Defining markers Geographic Coordinates References
Holocene 0.117
GSSP Golden Spike.svg
NGRIP2 ice core,


  • End of the Younger Dryas stadial (cold stage)
75°06′00″N 42°19′12″W / 75.1000°N 42.3200°W / 75.1000; -42.3200
Pleistocene 2.588
GSSP Golden Spike.svg
Monte San Nicola Section,

Sicily, Italy

  • Base of magnetic polarity chronozone C2r (Matuyama).
  • Extinction of Discoaster pentaradiatus and Discoaster surculus (Calcareous nannofossil).
37°08′49″N 14°12′13″E / 37.1469°N 14.2035°E / 37.1469; 14.2035
Pliocene 5.333
GSSP Golden Spike.svg
Heraclea Minoa section

Heraclea Minoa, Sicily, Italy

  • Top of magnetic polarity chronozone C3r.
  • First appearance of Ceratolithus acutus and near extinction of Triquetrorhabdulus rugosus (Calcareous nannofossil).
37°23′30″N 13°16′50″E / 37.3917°N 13.2806°E / 37.3917; 13.2806
Miocene 23.03
GSSP Golden Spike.svg
Lemme-Carrosio Section,

Carrosio, Italy

  • Base of magnetic polarity chronozone C6Cn.2n.
  • Near first appearance of Paragloborotalia kugleri (Planktonic foraminifera).
44°39′32″N 8°50′11″E / 44.6589°N 8.8364°E / 44.6589; 8.8364
Oligocene 33.9
GSSP Golden Spike.svg
Massignano Section,

Massignano, Ancona, Italy

43°31′58″N 13°36′04″E / 43.5328°N 13.6011°E / 43.5328; 13.6011
Eocene 56
GSSP Golden Spike.svg
Dababiya section,

Luxor, Egypt

  • Base of negative Carbon Isotope Excursion (CIE).
25°30′00″N 32°31′52″E / 25.5000°N 32.5311°E / 25.5000; 32.5311
Palaeocene 66
GSSP Golden Spike.svg
El Kef Section,

El Kef, Tunisia

36°09′13″N 8°38′55″E / 36.1537°N 8.6486°E / 36.1537; 8.6486
Upper Cretaceous 100.5
GSSP Golden Spike.svg
Mont Risoux,

Hautes-Alpes, France

44°23′33″N 5°30′43″E / 44.3925°N 5.5119°E / 44.3925; 5.5119
Lower Cretaceous 145


  • Magnetic—base of Chron M18r
  • Base of Calpionellid zone B
Upper Jurassic 163.5 Candidate sections:
  • Horizon of Cardioceras redcliffense (Ammonite).
Middle Jurassic 174.1
GSSP Golden Spike.svg
Fuentelsaz, Spain
  • First appearance of Leioceras opalinum and Leioceras lineatum
  • Biologic: First appearance of genus Leioceras (Ammonite).
41°10′15″N 1°50′00″W / 41.1708°N 1.8333°W / 41.1708; -1.8333
Lower Jurassic 201.3
GSSP Golden Spike.svg
Kuhjoch section, Karwendel mountains, Northern Calcareous Alps, Austria
  • Near first appearance of smooth Psiloceras spela group (Ammonite).
47°29′02″N 11°31′50″E / 47.4839°N 11.5306°E / 47.4839; 11.5306
Upper Triassic 235
GSSP Golden Spike.svg
Prati di Stuores, Dolomites, Italy
  • First appearance of Daxatina canadensis (Ammonite).
  • Near first appearance of Metapolygnathus polygnathiformis (Conodont).
  • Above magnetic zone S2n.
46°31′37″N 11°55′49″E / 46.5269°N 11.9303°E / 46.5269; 11.9303
Middle Triassic 247.2 Candidate sections:
  • First appearance of Chiosella timorensis (Conodont).
  • Magnetic: Base of magnetic zone MT1n.
45°04′27″N 28°48′08″E / 45.0742°N 28.8022°E / 45.0742; 28.8022
Lower Triassic 252.2
GSSP Golden Spike.svg
Meishan, Zhejiang, China
  • First appearance of Hindeodus parvus (Conodont).
31°04′47″N 119°42′21″E / 31.0798°N 119.7058°E / 31.0798; 119.7058
Permian 298.9
GSSP Golden Spike.svg
Aidaralash, Ural Mountains, Kazakhstan
  • First appearance of Streptognathodus isolatus within the morphotype Streptognathodus wabaunsensis chronocline (Conodont).
50°14′45″N 57°53′29″E / 50.2458°N 57.8914°E / 50.2458; 57.8914
Pennsylvanian 323.2
GSSP Golden Spike.svg
Arrow Canyon, Nevada, USA
  • First appearance of Declinognathodus nodiliferus (Conodont).
36°44′00″N 114°46′40″W / 36.7333°N 114.7778°W / 36.7333; -114.7778
Mississippian 358.9
GSSP Golden Spike.svg
La Serre, Montagne Noire, France
  • First appearance of Siphonodella sulcata (Conodont).
  • In 2006 it was discovered that this GSSP has biostratigraphic problems.
43°33′20″N 3°21′26″E / 43.5555°N 3.3573°E / 43.5555; 3.3573
Devonian 419.2
GSSP Golden Spike.svg
Klonk, Prague, Czech Republic
  • First appearance of Monograptus uniformis (graptolite).
49°51′18″N 13°47′31″E / 49.8550°N 13.7920°E / 49.8550; 13.7920
Silurian 443.4
GSSP Golden Spike.svg
Dob's Linn, Moffat, U.K.
  • First appearance of Akidograptus ascensus and Parakidograptus acuminatus (Graptolite).
  • 1.6 m above the base of the Birkhill Shale Formation.
55°26′24″N 3°16′12″W / 55.4400°N 3.2700°W / 55.4400; -3.2700
Ordovician 485.4
GSSP Golden Spike.svg
Greenpoint section

Green Point, Newfoundland, Canada

  • First appearance of Iapetognathus fluctivagus (Conodont).
  • Planktonic graptolites occur 4.8 m above boundary.
  • Coincides with a peak in carbon isotopes.
49°40′58″N 57°57′55″W / 49.6829°N 57.9653°W / 49.6829; -57.9653
Cambrian 541
GSSP Golden Spike.svg
Fortune head section,

Newfoundland, Canada

47°04′34″N 55°49′52″W / 47.0762°N 55.8310°W / 47.0762; -55.8310
Era Period Precambrian
Ediacaran 635
GSSP Golden Spike.svg
Enorama Creek section

Flinders Ranges, South Australia

  • Worldwide distinct cap carbonates.
  • Beginning of a distinctive pattern of secular changes in carbon isotopes.
31°19′53″S 138°38′00″E / 31.3314°S 138.6334°E / -31.3314; 138.6334
Cryogenian 850
GSSA Golden Clock.svg
Defined chronometrically now. GSSP is in progress.
Tonian 1000
GSSA Golden Clock.svg
Defined chronometrically
Stenian 1200
GSSA Golden Clock.svg
Defined chronometrically
Ectasian 1400
GSSA Golden Clock.svg
Defined chronometrically
Calymmian 1600
GSSA Golden Clock.svg
Defined chronometrically
Statherian 1800
GSSA Golden Clock.svg
Defined chronometrically
Orosirian 2050
GSSA Golden Clock.svg
Defined chronometrically
Rhyacian 2300
GSSA Golden Clock.svg
Defined chronometrically
Siderian 2500
GSSA Golden Clock.svg
Defined chronometrically
Archaean & Hadean
Neoarchaean 2800
GSSA Golden Clock.svg
Mesoarchaean 3200
GSSA Golden Clock.svg
Palaeoarchaean 3600
GSSA Golden Clock.svg
Eoarchaean 4000
GSSA Golden Clock.svg
Hadean 4567
GSSA Golden Clock.svg

Global Standard Stratigraphic Age (GSSAs)

Because defining a GSSP depends on finding well-preserved geologic sections and identifying key events, this task becomes more harder as one goes farther back in time. Before 640 million years ago, boundaries on the geologic timescale are defined simply by reference to fixed dates, known as "Global Standard Stratigraphic Ages". The oldest GSSP is the one that marks the start of the Ediacaran at 635 million years ago.

Images for kids

GSSP Facts for Kids. Kiddle Encyclopedia.