The Gelasian is an age in the international

geologic timescale The geologic time scale, or geological time scale, (GTS) is a representation of time based on the rock record of Earth. It is a system of chronological dating that uses chronostratigraphy (the process of relating strata to time) and geochr ...

or a

stage Stage or stages may refer to: Acting * Stage (theatre), a space for the performance of theatrical productions * Theatre, a branch of the performing arts, often referred to as "the stage" * ''The Stage'', a weekly British theatre newspaper * Sta ...

chronostratigraphy Chronostratigraphy is the branch of stratigraphy that studies the ages of rock strata in relation to time. The ultimate aim of chronostratigraphy is to arrange the sequence of deposition and the time of deposition of all rocks within a geologic ...

, being the earliest or lowest subdivision of the

Quaternary The Quaternary ( ) is the current and most recent of the three periods of the Cenozoic Era in the geologic time scale of the International Commission on Stratigraphy (ICS). It follows the Neogene Period and spans from 2.58 million year ...

Period/System and

Pleistocene The Pleistocene ( , often referred to as the ''Ice age'') is the geological Epoch (geology), epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fina ...

Epoch/Series. It spans the time between 2.58 Ma (million years ago) and 1.80 Ma. It follows the

Piacenzian The Piacenzian is in the international geologic time scale the upper stage or latest age of the Pliocene. It spans the time between 3.6 ± 0.005 Ma and 2.588 ± 0.005 Ma (million years ago). The Piacenzian is after the Zanclean and is followed ...

Stage (part of the

Pliocene The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58Calabrian Stage.

Definition

The Gelasian was introduced in the geologic timescale in 1998.Rio, D., Sprovieri, R., Castradori, D., Di Stefano, E
"The Gelasian Stage (Upper Pliocene): A new unit of the global standard chronostratigraphic scale"
''

Episodes Episodes may refer to: * Episode An episode is a narrative unit within a larger dramatic work or documentary production, such as a series intended for radio, television or streaming consumption. The noun ''episode'' is derived from the Greek ...

'', Vol. 21, No. 1, March 1998. pp 82-87. Retrieved March 18, 2020. It is named after the Sicilian city of

Gela Gela (Sicilian and ; grc, Γέλα) is a city and (municipality) in the Autonomous Region of Sicily, Italy; in terms of area and population, it is the largest municipality on the southern coast of Sicily. Gela is part of the Province of Ca ...

in the south of the island. In 2009 it was moved from the

Pliocene The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58Pleistocene The Pleistocene ( , often referred to as the ''Ice age'') is the geological Epoch (geology), epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fina ...

so that the

geologic time scale The geologic time scale, or geological time scale, (GTS) is a representation of time based on the rock record of Earth. It is a system of chronological dating that uses chronostratigraphy (the process of relating strata to time) and geochr ...

would be more consistent with the key changes in Earth's climate, oceans, and biota that occurred 2.58 million years ago. The base of the Gelasian is defined magnetostratigraphically as the base of the Matuyama (C2r)

chronozone A chronozone or chron is a unit in chronostratigraphy, defined by events such as geomagnetic reversals (magnetozones), or based on the presence of specific fossils (biozone or biochronozone). According to the International Commission on Strati ...

(at the Gauss-Matuyama magnetostratigraphic boundary), isotopic stage 103. Above this line notable extinctions of the calcareous nanofossils occur: ''Discoaster pentaradiatus'' and ''Discoaster surculus''.Gradstein ''et al.'' (2005), p. 28 The

GSSP A Global Boundary Stratotype Section and Point (GSSP) is an internationally agreed upon reference point on a stratigraphic section which defines the lower boundary of a stage on the geologic time scale. The effort to define GSSPs is conducted ...

for the Gelasian is located at the Monte Sant Nicola near Gela. The top of the Gelasian is defined magnetostratigraphically as the end of the Olduvai (C2n) chronozone, and faunally as the extinction level of the calcareous nanofossil ''Discoaster brouweri'' (base of

biozone In biostratigraphy, biostratigraphic units or biozones are intervals of geological strata that are defined on the basis of their characteristic fossil taxa, as opposed to a lithostratigraphic unit which is defined by the lithological properties ...

CN13). Above the Gelasian as the first occurrences of the calcareous nanofossil '' Gephyrocapsa sp.'' and the extinction level of the planktonic

foraminifer Foraminifera (; Latin for "hole bearers"; informally called "forams") are single-celled organisms, members of a phylum or class of amoeboid protists characterized by streaming granular ectoplasm for catching food and other uses; and commonly a ...

''Globigerinoides extremus''

Climate

During the Gelasian the ice sheets in the

Northern Hemisphere The Northern Hemisphere is the half of Earth that is north of the Equator. For other planets in the Solar System, north is defined as being in the same celestial hemisphere relative to the invariable plane of the solar system as Earth's Nort ...

began to grow, which is seen as the beginning of the

Quaternary ice age The Quaternary ( ) is the current and most recent of the three periods of the Cenozoic Era in the geologic time scale of the International Commission on Stratigraphy (ICS). It follows the Neogene Period and spans from 2.58 million ye ...

. Deep sea core samples have identified approximately 40

marine isotope stage Marine isotope stages (MIS), marine oxygen-isotope stages, or oxygen isotope stages (OIS), are alternating warm and cool periods in the Earth's paleoclimate, deduced from oxygen isotope data reflecting changes in temperature derived from data f ...

s (MIS 103 – MIS 64) during the age. Thus, there have probably been about 20 glacial cycles of varying intensity during the Gelasian.

Europe

In the regional glacial history of the

Alps The Alps () ; german: Alpen ; it, Alpi ; rm, Alps ; sl, Alpe . are the highest and most extensive mountain range system that lies entirely in Europe, stretching approximately across seven Alpine countries (from west to east): France, Sw ...

, this age is now called Biber. It corresponds to

Pre-Tegelen The Tiglian, also referred to as the Tegelen, is a temperate complex stage in the glacial history of Northern Europe. It is preceded by the Praetiglian (stage). The stage was introduced by Zagwijn in 1957 based on geological formations in Tegelen i ...

and

Tegelen Tegelen ( li, Tegele) is a village in the municipality of Venlo, situated in the Netherlands. It was an independent municipality until 2001, when it was merged into the municipality of Venlo. Tiglian The name of the glacial stage of Tiglian (p ...

in Northern Europe.German Stratigraphic Commission: Stratigraphische Tabelle von Deutschland 2016
/ref> During the Gelasian, the

Red Crag Formation The Red Crag Formation is a geological formation in England. It outcrops in south-eastern Suffolk and north-eastern Essex. The name derives from its iron-stained reddish colour and ''crag'' which is an East Anglian word for shells. It is part of th ...

of Butley, the Newbourn Crag, the

Norwich Crag Formation The Norwich Crag Formation is a stratigraphic unit of the British Pleistocene Epoch. It is the second youngest unit of the Crag Group, a sequence of four geological formations spanning the Pliocene to Lower Pleistocene transition in East Anglia. I ...

and the

Weybourne Crag Formation The Weybourne Crag Formation is a geologic formation in England. It preserves fossils. See also * List of fossiliferous stratigraphic units in England See also * Lists of fossiliferous stratigraphic units in Europe * Lists of fossilifero ...

(all from

East Anglia East Anglia is an area in the East of England, often defined as including the counties of Norfolk, Suffolk and Cambridgeshire. The name derives from the Anglo-Saxon kingdom of the East Angles, a people whose name originated in Anglia, in ...

, England) were deposited. The Gelasian is an equivalent of the

Praetiglian The Tiglian, also referred to as the Tegelen, is a temperate complex stage in the glacial history of Northern Europe. It is preceded by the Praetiglian (stage). The stage was introduced by Zagwijn in 1957 based on geological formations in Tegelen i ...

and

Tiglian The Tiglian, also referred to as the Tegelen, is a temperate complex stage in the glacial history of Northern Europe. It is preceded by the Praetiglian (stage). The stage was introduced by Zagwijn in 1957 based on geological formations in Tegelen i ...

Stages as defined in the

Netherlands ) , anthem = ( en, "William of Nassau") , image_map = , map_caption = , subdivision_type = Sovereign state , subdivision_name = Kingdom of the Netherlands , established_title = Before independence , established_date = Spanish Netherl ...

, which are commonly used in northwestern Europe.

References

Notes

Literature

* (''eds.'') (2005) ''A Geologic Time Scale 2004'', Cambridge University Press, Cambridge, UK, *; 1998
''The Gelasian Stage (Upper Pliocene): A new unit of the global standard chronostratigraphic scale''
Episodes, 21(2): 82-87 {{- Pleistocene geochronology Geological ages