A geologic timescale ontology and service

We have developed an OWL ontology for the geologic timescale, derived from a Unified Modeling Language (UML) model that formalized the practice of the International Commission for Stratigraphy (ICS) (Cox and Richard 2005). The UML model followed the ISO/TC 211 modeling conventions, and was the basis for an XML implementation that was integrated into GeoSciML 3.0. The OWL ontology is derived using rules for generating OWL ontologies from ISO-conformant UML models, as provided in a (draft) standard from ISO/TC 211. The basic ontology is also aligned with SKOS to allow multilingual labels, and to enable delivery through a standard vocabulary interface. All versions of the International Stratigraphic Chart from 2004 to 2014 have been encoded using the ontology. Following ICS practice, the elements of the timescale retain the same identifiers across the multiple versions, though the information describing each geochronologic unit evolves with the versions of the timescale. The timescales are published through multiple web interfaces and APIs.