Gelasian
first age of the Pleistocene Epoch
The Gelasian is an age in the international geologic timescale or a stage in chronostratigraphy, being the earliest or lowest subdivision of the Quaternary Period/System and Pleistocene Epoch/Series. It spans from 2.58–1.80 million years ago, following the Piacenzian Age (from the Pliocene Epoch) and preceding the Calabrian Age.
Definition
The Gelasian was introduced in the geologic timescale in August 1996. It is named after the Sicilian city of Gela in the south of the island, with its GSSP being located near the city at Monte San Nicola. In 2009 it was moved from the Pliocene to the Pleistocene so that the geologic time scale would be more consistent with the key changes in Earth's climate, oceans, and biota that occurred 2.58 million years ago.
Magnetostratigraphically, the base of the Gelasian is defined as the base of the Matuyama (C2r) chronozone (at the Gauss-Matuyama magnetostratigraphic boundary), at isotopic stage 103. Above this line, notable extinctions of the calcareous nannofossils occur: Discoaster pentaradiatus and Discoaster surculus. Similarly, the top of the Gelasian is magnetostratigraphically defined as the end of the Olduvai (C2n) chronozone, and faunally as the extinction level of the calcareous nannofossil Discoaster brouweri (base of biozone CN13). Above the Gelasian are the first occurrences of the calcareous nanofossil Gephyrocapsa sp., and the extinction level of the planktonic foraminifer Globigerinoides extremus.
Climate
During the Gelasian the ice sheets in the Northern Hemisphere began to grow, which is seen as the beginning of the Quaternary ice age.
This brief starts where responsible research should: with the source description of “Gelasian” as first age of the Pleistocene Epoch. Everything that follows is an evidence route, not borrowed authority.
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The subject matters to the general reference register because the source frames it as first age of the Pleistocene Epoch. Its deeper value depends on whether names, dates, institutions and citations support that framing.
Named sources, stable identifiers and responsible institutions provide the strongest route from overview to verifiable evidence. The source revision retrieved here is dated Sep 26, 2025. The linked authority identifier is Q428579. Authority coordinates are 37.147, 14.204. 1 of 1 selected statements include explicit references; 1 carry qualifiers and 0 use preferred rank. The first chronological checks are 1996 and 2009.
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This entry incorporates text from “Gelasian” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.