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Digital Mapping Techniques '98 -- Workshop Proceedings
U.S. Geological Survey Open-File Report 98-487

Progress Toward Development of the National Geologic Map Database

By David R. Soller1 and Thomas M. Berg2

1U.S. Geological Survey
908 National Center
Reston, VA 20192
Telephone: (703) 648-6907
Fax: (703) 648-6937

2Ohio Geological Survey
4383 Fountain Square Dr.
Columbus, OH 43224
Telephone: (614) 265-6988
Fax: (614) 268-3669

The Geologic Mapping Act of 1992 and its reauthorization in 1997 (PL105-36) requires that a National Geologic Map Database (NGMDB) be designed and built by the U.S. Geological Survey (USGS), the state geological surveys, and other entities participating in the National Cooperative Geologic Mapping Program. The Act notes that the NGMDB is intended to serve as a "national archive" of geologic maps, to provide the information needed to address various societal issues. The Act required the NGMDB to also include the following related map themes: geophysics, geochemistry, paleontology, and geochronology. In this progress report, the term "geoscience" is used to refer to these five map themes.

In mid-1995, the general stipulations in the Act were addressed in the proposed design and implementation plan developed within the USGS and the Association of American State Geologists (AASG). This plan was summarized in Soller and Berg (1995). Because most maps are not yet in digital form and because many organizations produce and distribute geologic maps, it was decided to develop the NGMDB in several phases. The first two phases are addressed here. The first and most fundamental phase is a comprehensive, searchable catalog of all geoscience maps in the United States, in either paper or digital format. The users, upon searching the NGMDB catalog and identifying the map(s) they need, are to be linked to the appropriate organization for further information and how to procure the map. That organization could be a participating state or federal agency, association, or private company. The second phase of the project focuses on public access to digital geoscience maps, and on the development of digital map standards and guidelines needed to improve the utility of those digital maps.

In late 1995, work began on phase one. The formation of several Standards Working Groups in mid-1996 initiated work on phase two. Progress through mid-1997 is summarized in Soller and Berg (1997). At the Digital Mapping Techniques '98 workshop, a series of presentations and discussion sessions provided updates on the NGMDB and, specifically, on the activities of the Standards Working Groups. This report summarizes progress since mid-1997. Further and more current information may be found at the NGMDB project-information Web site, at The searchable database is available at


The catalog now contains bibliographic information for most formal series USGS maps, USGS maps contained in book publications, and many maps from the USGS open-file series. The catalog is estimated to be about 32% complete, and contains georeferenced information for about 53% of all USGS maps (about 12,000 in the catalog) and 2% of state geological survey maps. This represents more than a six-fold increase in information since last year. Through development of a Web-based data-entry form, we are now working with state geological surveys to bring their map information into the catalog; this has begun as a pilot effort, with cooperation of the Illinois State Geological Survey and the West Virginia Geological and Economic Survey. Entry of state geological survey publications will now become a top priority.


The following summaries concern activities of the AASG/USGS Standards Working Groups formed in mid-1996. General information about the Working Groups, and details of their activities, are available at

Geologic Map Symbols

A draft standard for geologic map symbology, published in a USGS open-file in 1995, was revised by the NGMDB project and members of the USGS Western Region Publications Group and was circulated for internal review in late 1997. The revised draft is now being prepared as a proposed Federal standard, for consideration by the Federal Geographic Data Committee. We also have negotiated with Environmental Systems Research Institute, Inc., a cooperative plan to develop an Arc/Info and ArcView version of the symbols and patterns; for more information, see

Digital Mapping

The Data Capture Working Group last year coordinated the first workshop on digital mapping techniques for state and federal geologists, cartographers, and managers. Sponsored by the Kansas Geological Survey, the meeting was attended by 70 members of 30 state geological surveys, the USGS, and the Geological Survey of Canada. The proceedings were published (Soller, 1997) and served on-line ( Copies of the Proceedings may be obtained from Soller or Berg.

Map Publication Requirements

Through the USGS Geologic Division Information Council, one of us (Soller) has developed a proposed USGS Publication Requirements for Digital Map Products. When this document is approved by the USGS, perhaps in late 1998, a less USGS-specific version will be proposed to the AASG through the Map Publication Guidelines Working Group. This Working Group then would work with the AASG and the USGS to craft an acceptable guideline for all maps available through the NGMDB.


The Metadata Working Group has developed a report, which provides guidance on the creation and management of well-structured formal metadata for digital maps (see The report also contains links to metadata-creation tools and general discussions of metadata concepts (see, for example, "Metadata in Plain Language", at The Working Group welcomes your comments on its report.

Geologic Map Data Model

Following numerous presentations, discussions, and progress reports (for example, Raines and others, 1997), in October, 1997, the Working Group posted to the NGMDB project's Web site for public comment a report describing the proposed standard data model. To permit thorough evaluation of the data model, the concepts and specifications described in that report must be translated into software tools that 1) organize and manage the geologic map information in the data model format, and 2) offer a user-friendly interface for data entry and analysis. The Working Group began building some prototype tools in mid-1997. Through presentations and discussions with potential users, the tools have been refined, and are now available for use. These tools are not intended as "production" tools, but are merely prototypes that will aid in the evaluation of the data model.

The data model and tools were presented for discussion in a special session at the Digital Mapping Techniques '98 workshop in late May, 1998. A number of attendees from the state geological surveys expressed interest in helping to refine the model and develop it into a geoscience-community standard. It was agreed that an extended period of evaluation among the states and USGS would begin as soon as possible.

At a three-day workshop in June, 1998, the first formal review of the data model was conducted. The workshop was attended by 28 members of the USGS, state geological surveys, and the federal and provincial surveys of Canada. An overview of the conceptual model and software tools was followed by a hands-on session and facilitated discussion. Throughout, the importance of discussion and consensus-building was emphasized; the process of developing this standard data model must be an open and inclusive one, because a proposed standard cannot actually function as a standard if it is not widely accepted and used. At this workshop, it was resolved to: 1) proceed with development of the data model and software tools; 2) broaden the participation in its further development; 3) begin the extended period of on-site evaluation at state, provincial, and federal surveys; and 4) work toward adoption of the data model as a national standard.

To facilitate the review and discussion of the data model after the June workshop, a Web conference was developed (see Discussion topics include: 1) general conceptual issues related to the data model and geologic mapping; 2) specific problems with the data model; 3) development of standard geologic terms; and 4) software tools. This site, and the NGMDB project's Web site, also offer access to the data model report and software tools. All interested parties in the state geological surveys, the USGS, and elsewhere are invited to evaluate them, and to help us develop the prototype into a community standard that will serve both the scientist and the general public.


In April, 1998, an on-line geologic names lexicon, "GEOLEX", became available at the NGMDB Web site. This lexicon is under construction, and is estimated to be about 65% complete. GEOLEX is a consolidated, revised, and error-corrected database derived from the USGS GNULEX and GEONAMES databases. It is intended to be the comprehensive, authoritative listing of geologic names approved for usage by the USGS, and will be available as a resource for geologic mappers nationwide.


Work has begun on a National Paleontologic Database and a set of Web pages to support the Database and to permit searches. A public release is expected in 1999. To provide users with information about current mapping activities, a Geologic Mapping in Progress Database has been developed. This year, its scope and design were proposed to the AASG at their annual meeting in Portland, ME, and a prototype database was built. The database is being expanded to contain information about 1998 mapping activities, and a Web interface to this database is being designed. Public access is expected by early 1999. Progress continues to be made toward various other goals of the NGMDB, including the serving of standardized digital map products over the Internet. The project's Web site will continue to provide current information on these subjects.


Raines, G.L., Brodaric, Boyan, and Johnson, B.R., 1997, Progress report -- Digital geologic map data model, in David R. Soller, ed., Proceedings of a workshop on digital mapping techniques: Methods for geologic map data capture, management, and publication: U.S. Geological Survey Open-File Report 97-269, p. 43-46.

Soller, D.R., editor, 1997, Proceedings of a workshop on digital mapping techniques: Methods for geologic map data capture, management, and publication: U.S. Geological Survey Open-File Report 97-269, 120 p.

Soller, D.R., and Berg, T.M., 1995, Developing the National Geologic Map Database: Geotimes, v. 40, no. 6, p. 16-18.

Soller, D.R., and Berg. T.M., 1997, The National Geologic Map Database -- A progress report: Geotimes, v. 42, no. 12, p. 29-31.

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U.S.Department of the Interior, U.S. Geological Survey
Maintained by Dave Soller
Last updated 10.06.98