Toarcian
Fourth and last age of the Early Jurassic
title: "Toarcian" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["toarcian", "early-jurassic", "geological-ages"] description: "Fourth and last age of the Early Jurassic" topic_path: "philosophy" source: "https://en.wikipedia.org/wiki/Toarcian" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0
::summary Fourth and last age of the Early Jurassic ::
::data[format=table title="Infobox geologic timespan"]
| Field | Value |
|---|---|
| name | Toarcian |
| color | Toarcian |
| time_start | 184.2 |
| time_start_uncertainty | 0.3 |
| time_end | 174.7 |
| time_end_uncertainty | 0.8 |
| image_map | File:180Ma Mollweide.png |
| caption_map | Map of Earth at 180 million years ago; the boundaries of present-day landmasses, countries, and states are superimposed as black outlines |
| timeline | Jurassic |
| name_formality | Formal |
| celestial_body | earth |
| usage | Global (ICS) |
| timescales_used | ICS Time Scale |
| chrono_unit | Age |
| strat_unit | Stage |
| timespan_formality | Formal |
| lower_boundary_def | Peniche, Portugal |
| lower_gssp_location | FAD of the Ammonite D. (E.) simplex |
| lower_gssp_coords | |
| lower_gssp_accept_date | 2014 |
| upper_boundary_def | FAD of the Ammonites Leioceras opalinum and Leioceras lineatum |
| upper_gssp_location | Fuentelsaz, Spain |
| upper_gssp_coords | |
| upper_gssp_accept_date | 2000 |
| :: |
| name = Toarcian | color = Toarcian | time_start = 184.2 | time_start_uncertainty = 0.3 | time_end = 174.7 | time_end_uncertainty = 0.8 | image_map =File:180Ma Mollweide.png | caption_map =Map of Earth at 180 million years ago; the boundaries of present-day landmasses, countries, and states are superimposed as black outlines | image_outcrop = | caption_outcrop = | image_art = | caption_art = | timeline = Jurassic | formerly_part_of = | partially_contained_in = | partially_contains = | name_formality = Formal | name_accept_date = | alternate_spellings = | synonym1 = | synonym1_coined = | synonym2 = | synonym2_coined = | synonym3 = | synonym3_coined = | nicknames = | former_names = | proposed_names = | celestial_body = earth | usage = Global (ICS) | timescales_used = ICS Time Scale | formerly_used_by = | not_used_by = | chrono_unit = Age | strat_unit = Stage | proposed_by = | type_section = | timespan_formality = Formal | lower_boundary_def = Peniche, Portugal | lower_gssp_location = FAD of the Ammonite D. (E.) simplex | lower_gssp_coords = | lower_gssp_accept_date = 2014 | upper_boundary_def = FAD of the Ammonites Leioceras opalinum and Leioceras lineatum | upper_gssp_location = Fuentelsaz, Spain | upper_gssp_coords = | upper_gssp_accept_date = 2000 | o2 = | co2 = | temp = | sea_level = The Toarcian is, in the ICS' geologic timescale, an age and stage in the Early or Lower Jurassic. It spans the time between 184.2 Ma (million years ago) and 174.7 ±0.8 Ma. It follows the Pliensbachian and is followed by the Aalenian.
The Toarcian Age began with the Toarcian Oceanic Anoxic Event, a major anoxic event associated with marine extinctions and increased global temperatures that sets its fossil faunas apart from the previous Pliensbachian age. It is believed to have ended with a global cooling event known as the Comptum Cooling Event, although whether it represented a worldwide event is controversial.
Stratigraphic definitions
The Toarcian takes its name from the city of Thouars, just south of Saumur in the Loire Valley of France. The stage was introduced by French palaeontologist Alcide d'Orbigny in 1842, after examining rock strata of this age in a quarry near Thouars.
In Europe this period is represented by the upper part of the Lias.
The base of the Toarcian is defined as the place in the stratigraphic record where the ammonite genus Eodactylites first appears. A global reference profile (a GSSP) for the base is located at Peniche, Portugal. The top of the stage is at the first appearance of ammonite genus Leioceras.
In the Tethys domain, the Toarcian contains the following ammonite biozones:
- zone of Pleydellia aalensis
- zone of Dumortieria pseudoradiosa
- zone of Phlyseogrammoceras dispansum
- zone of Grammoceras thouarcense
- zone of Haugia variabilis
- zone of Hildoceras bifrons
- zone of Harpoceras serpentinum
- zone of Dactylioceras tenuicostatum
References
Sources
- ; 2004: A Geologic Time Scale 2004, Cambridge University Press.
- ; 1842: Paléontologie française. 1. Terrains oolitiques ou jurassiques, Bertrand, Paris.
- Elmi, S., Rulleau, L., Gabilly, J. & Mouterde, R. 1997: Toarcien. In: Cariou, E. & Hantzpergue, P. (eds): Biostratigraphie du Jurassique ouest-européen et méditerranéen. Bulletin du Centre des Recherches, Elf Explor. Prod. Mém., 17.
References
- (September 2016). "Base of the Toarcian Stage of the Lower Jurassic defined by the Global Boundary Stratotype Section and Point (GSSP) at the Peniche section (Portugal)". Episodes.
- (September 2001). "The Global Boundary Stratotype Section and Point (GSSP) of the Toarcian-Aalenian Boundary (Lower-Middle Jurassic)". Episodes.
- Benton, Michael J.. (2012). "Prehistoric Life". Dorling Kindersley.
- For a detailed geologic timescale see Gradstein ''et al.'' (2004)
- (September–October 2013). "Ammonite-benthic Foraminifera turnovers across the Lower-Middle Jurassic transition in the Lusitanian Basin (Portugal)". [[Geobios]].
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