NORTON: A PROPOSED NORTH AMERICAN GEOLOGIC MAP DATA CONCEPTUAL MODEL

The Data Model Design Team (Eric Boisvert-GSC, Boyan Brodaric-GSC, Jordan Hastings-UCSB/USGS, Bruce Johnson-USGS, James McDonald-OH.GS, S. M. Richard-AZ.GS, Peter Schweitzer-USGS, and Gerald Weisenfluh-KY.GS.) was established in 1999 by the North American Data Model Steering Committee (NADMSC) with the purpose of drafting a geological map data model for consideration as a standard for developing interoperable geologic-map-centered databases by state, provincial, and federal geological surveys. Version 1.0 of a proposed standard model is now released for public review and comment. The model is designed to be a technology-neutral conceptual model that can form the basis for a web-based interchange format using evolving information technology (e.g., XML, RDF, OWL), and guide implementation of geoscience databases in a common conceptual framework. The intended purpose is to allow geologic information sharing between geologic map data providers and users, independent of local information system implementation.

The model emphasizes geoscience concepts and relationships related to information presented on geologic maps [Johnson et al., 1998, Richard, 1999; Brodaric & Hastings, 2000; Soller et al., 2002]. Design has been guided by an informal requirements analysis, documentation of existing databases, technology developments, and other standardization efforts in the geoscience and computer-science communities.

The model evolved from a scheme of top-level classes, sequentially developed subtype hierarchies for each class, and schema for the properties of the classes and relationships between them. Top-level geologic classes in the model are EarthMaterial (substance), GeologicUnit (parts of the Earth), GeologicAge, GeologicStructure, Fossil, GeologicProcess, GeologicRelation, GeologicProperty, and GeologicAge. A ControlledVocabulary class represents terminology systems used to specify many of the properties that define geologic concepts. A key aspect of the model is the notion that representation of the conceptual framework (ontology) that underlies geologic map data must be part of the model, because this framework changes with time and understanding, and varies between information providers.