Definitions this project works from, and the reference libraries used to standardize units, rocks, ages and rank/naming terms.
What counts as a geological unit here, and how stratigraphy is standardized in this project.
The sense used here is narrower than the everyday term. In the strict sense, a geological unit
is defined by, at minimum, constituent rocks and chronology — relative, absolute, or even
just a formally established name. In the broad sense, the category also includes other features
associated with those units, such as fossils and structural geology (faults, suture zones,
etc.). Mining (mineria[]) is a separate group that follows the same naming
logic but is tracked separately from units (units[]).
For geological units, the reference is what's established by the International Commission on Stratigraphy (ICS) — see Chronology — but the project also adopts terms in common use in the regional tectonic literature, even without formal rank: complex, suite, nappe, among others (see Nomenclature for the full vocabulary). For the vector files, the standard used is the contact between units — see Stratigraphy.
Reference libraries this project standardizes against, and the working pages built on top of them.
Rock classification for mapping (USGS), with one difference: volcanic and plutonic rocks are grouped into a single class, Igneous.
Open Rock →International Chronostratigraphic Chart (ICS) — eon → era → period → epoch → age, with the age (Ma) of every boundary.
Open Chronology →Geological units, mineral occurrences and geometry extracted from the corpus — three tabs on one page.
Open Lexicon →Structure and contacts between units (IGME 5000) — two tabs, with vector visualization.
Open Stratigraphy →Formal rank hierarchy (Supergroup → Bed) and the informal/structural terms in use in the corpus (nappe, complex, suite, basin...).
Open Nomenclature →