Piacenzian
Second Pliocene age (3.600–2.58 Ma), named for fossiliferous marine clays around Piacenza.
Language and route: Italian place-name mediated by nineteenth-century scientific terminology. Piacenza, Emilia-Romagna, Italy (Latin Placentia) → historical scientific stage-name Piacenzian. This is a geographical/eponymic formation, not a Greek life-comparison compound.
Literal gloss: of Piacenza
The name and its history
Karl Mayer (Mayer-Eymar) · 1858
- What does the word literally mean?
- of Piacenza
- What did the original author mean?
- Mayer assigned fossil-rich marine deposits of the Piacenza region to a division of his younger Tertiary scheme.
- Why was the name needed?
- Italian Pliocene marine deposits had varied shell faunas and were being separated into regional stages with differing meanings, especially relative to Astian.
- What evidence supported the original concept?
- Extensive molluscan assemblages of northern Italian marine clays informed the original classification and comparisons with other European basins.
- How has geology changed the concept?
- The stage now ends at 2.58 Ma because the formerly Pliocene Gelasian was reassigned to the Pleistocene and Quaternary; the name survives that major classification revision.
Further historical context
Mayer assigned fossil-rich marine deposits of the Piacenza region to a division of his younger Tertiary scheme.
Italian Pliocene marine deposits had varied shell faunas and were being separated into regional stages with differing meanings, especially relative to Astian.
Extensive molluscan assemblages of northern Italian marine clays informed the original classification and comparisons with other European basins.
The stage now ends at 2.58 Ma because the formerly Pliocene Gelasian was reassigned to the Pleistocene and Quaternary; the name survives that major classification revision.
Editorial qualification
The original French spellings Plaisancien/Piacenzian vary in historic sources; do not silently impose the modern English spelling on Mayer’s text.
Related names
Neogene · Pliocene · Zanclean · Pleistocene · Quaternary · Gelasian
Sources
- International Commission on Stratigraphy, International Chronostratigraphic Chart v2026/06 — Primary authority for present unit names, hierarchy and boundary ages, not first coinages
- Cita (2009), Mediterranean Neogene stratigraphy: development and evolution through the centuries — Historic Mediterranean stage competition, fossil correlation, and international standardisation
- Reguant (2009), historical geography and names of the Neogene stages, Contributions to Science — Author, year and etymological source table for the standard Neogene stages
- ICS Subcommission on Neogene Stratigraphy, objectives and current unfinished GSSP work — Documents the unresolved Burdigalian GSSP and 2021 subepoch formalisation