NCGMP09 -- A DATABASE SCHEMA FOR DIGITAL PUBLICATION OF GEOLOGIC MAPS

After two decades experience with geologic-map GIS, the earth science community has yet to evolve a widely accepted schema for the GIS representation of a geologic map. Benefits of a standard schema would include better communication with map users, easier development of tools for creating and analyzing geologic maps, lower training costs, and easier map compilation.

We are developing a schema for the publication of a single geologic map. Creation of a single-map database, collection of field data, cartography, and databases for multiple maps are different (though related) problems. We began our effort with experience that included participation in previous and ongoing standards efforts (NGMDB, NADM, FGDC), use and construction of GIS tools for geologic map creation (ALACARTE and derivatives), extensive geologic mapping experience in diverse terrain, and much production GIS work. Our work is supported by the National Cooperative Geologic Mapping Program of the USGS.

Salient features of the schema include: (1) inclusion of both traditional, hierarchical Description of Map Units with free-form descriptions AND strongly-structured, tabular earth materials descriptions, (2) extensive feature-level metadata, (3) prescribed naming of all database elements, and (4) the schema is native to ArcGIS. We have translated existing databases into this schema. We have written tools that create an empty database, (partially) validate a database, check a database for certain geometric inconsistencies, and translate a database to open file formats. Documentation, example databases, and tools are online at http://ngmdb.usgs.gov/Info/standards/NCGMP09/.

In the coming months 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.