Guadalupian

The name and its history

George H. Girty (1902), originally called a regional “period” · See attributed dates and cited original / standardisation works; first-use priority qualified where noted

What does the word literally mean?

From guadalupe mountains. Immediate scientific language-route: Spanish geographical name → American geological English. This is a locality-based or geographical term, not a description of a universal geological event.

What did the original author mean?

Girty’s proposed regional North American Permian “period”, based on the distinctive marine faunas of the Guadalupe Mountains.

Why was the name needed?

Girty argued that fossils collected in West Texas differed from other North American fossil assemblages and represented a later Permian fauna; a new regional time name was needed.

What evidence supported the original concept?

Girty compared fossil faunas and stratigraphic sections, notably the distinctive Guadalupe limestones; his own original explanation is recorded in the USGS Geolex.

How has geology changed the concept?

The rank and content changed (regional “period”, series, stage, then globally recognised middle Permian series); it now spans Roadian, Wordian and Capitanian.

Further historical context

*Naming and context.* Girty argued that fossils collected in West Texas differed from other North American fossil assemblages and represented a later Permian fauna; a new regional time name was needed.

*Evidence and later scope.* Girty compared fossil faunas and stratigraphic sections, notably the distinctive Guadalupe limestones; his own original explanation is recorded in the USGS Geolex. The rank and content changed (regional “period”, series, stage, then globally recognised middle Permian series); it now spans Roadian, Wordian and Capitanian.

Editorial qualification

This is geographical Spanish via New World placenames, not a literal “mountains of a geological property” gloss.

Related names

Permian · Cisuralian · Lopingian · Asselian · Sakmarian · Artinskian · Kungurian · Roadian · Wordian · Capitanian · Wuchiapingian · Changhsingian · Fossil · Stratigraphy

Sources

1. ICS International Chronostratigraphic Chart (June 2026) — Current formal unit, order, rank and numerical age
2. USGS Geolex: Girty (1902) original Guadalupian proposal — Excerpt of original motivation, early title and later changes
3. Jin et al. (1997), Permian chronostratigraphic subdivisions, Episodes — International decision to adopt Urals, Texas and South China tripartition