DATABASE SCHEMA FOR NCGMP09—A PROPOSED STANDARD FORMAT FOR DIGITAL PUBLICATION OF GEOLOGIC MAPS

NCGMP09 is a database design proposed as a standard format for digital publication of geologic maps. It specifies a database schema to encode content analogous to that contained in a single, traditional geologic map published by the USGS and state geological surveys. The scheme is a distillation of various geoscience data models and includes the content we have empirically identified as that most commonly available in actual datasets. The database has been implemented as an ESRI geodatabase in order to adhere to USGS policy and because this is a widely used GIS, but the schema can be implemented using any spatially enabled database. Further, this design is intended to provide a stepping-stone toward development of multi-map databases, in particular the National Geologic Map Database (NGMDB). Our development process and design considerations are discussed in a companion presentation by Haugerud and others.

Documentation, example databases, and tools are online at http://ngmdb.usgs.gov/Info/standards/NCGMP09/. As a brief example of NCGMP09’s design, required tables include a GeologicMap feature dataset with (1) MapUnitPolygon and (2) ContactsAndFaults feature classes that are topologically linked; (3) a DescriptionOfMapUnits table that contains text description of units, along with age and symbolization information for the unit; (4) a StandardLithology table that specifies the lithologic composition of a map unit; (5) a Glossary table that defines terminology used in the database; and (6) a DataSources table that specifies provenance of items in the database on a feature-by-feature basis. Optional OverlayPolygon (e.g. alteration zones), ConcealedContactAndFault, and OtherLines (Dikes, veins, fold hinge surface traces) feature classes may be included to represent mapped features that do not participate in the map unit topology. Point feature classes may be included for point-located information (sample, strike and dip measurement, geochemical data); each data type is included in a separate point feature class with a standard collection of fields, along with fields specific to that data type. In the coming year we plan another round of revision and will write more tools to facilitate database creation. We solicit feedback on the database schema and collaboration in tool development.