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Digital Mapping Techniques '00 -- Workshop Proceedings
U.S. Geological Survey Open-File Report 00-325

The National Geologic Map Database: A Progress Report

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 reauthorizations in 1997 and 1999 (PL106-148) require that a National Geologic Map Database (NGMDB) be designed and built by the U.S. Geological Survey (USGS), with the assistance of 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 many 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 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 linked to the appropriate organization for further information about how to procure the map. (The organization could be a participating state or federal agency, association, or private company.) The map catalog is presently supported by two databases developed under the NGMDB project: 1) GEOLEX, a searchable geologic names lexicon; and 2) Geologic Mapping in Progress, which provides information on current mapping projects, prior to inclusion of their products in the map catalog. 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. The third phase proposes, in the long term, to develop an online, "living" database of geologic map information at various scales and resolution. The third phase is discussed in a separate paper in these proceedings.

In late 1995, work began on phase one. The formation of several Standards Working Groups in mid-1996 initiated work on phase two. Progress was summarized in Soller and Berg (1997, 1998, 1999a, and 1999b). At the Digital Mapping Techniques '98, '99, and '00 workshops, 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-1999. Further and more current information may be found at the NGMDB project-information Web site, at The searchable database is available at


The Map Catalog
The map catalog is designed to be a comprehensive, searchable catalog of all geoscience maps of the United States, in paper or digital format. Entries to the catalog include maps published in geological survey formal series and open-file series, maps in book publications, maps in theses and dissertations, maps published by park associations and scientific societies, maps published by other agencies, and publications that do not contain a map but instead provide a geological description of an area (for example, a state park). The catalog now contains a record for each of nearly 26,000 map products. Essentially 100% of all USGS maps have been recorded in the catalog, and in the past year emphasis shifted to assist the State geological surveys to enter all other maps into the catalog. By the date of the DMT'00 meeting, geological surveys in eight states (Arizona, Illinois, Minnesota, Nevada, New York, Ohio, Oklahoma, and West Virginia) were entering map records, as well as one University (Stanford); significantly more participation is anticipated in the coming months. [Note: as of early September, 2000, a total of 20 states were participating; the newly-contributing states were Arkansas, California, Colorado, Delaware, Florida, Kansas, Nebraska, Pennsylvania, South Dakota, Vermont, Washington, and Wyoming.] Web usage statistics indicate since entry of all USGS maps a clear increase in multiple visits to the site per month. This suggests the site is becoming a more useful resource, and additional increases in use are expected as the state geological survey maps are entered into the catalog.

Numerous enhancements were made this year to software and hardware, which is anticipated to increase the useability of the search engine and the Search Results pages, and to decrease the response time to the Web user. Availability of each USGS product is now tracked, and if the product is out-of-stock or out-of-print, users are directed to a list of depository libraries. New search criteria include product publisher, date of publication (specific or a range), and a map scale (specific or a range).

Geologic Names Lexicon
The searchable, on-line, geologic-names lexicon ("GEOLEX") now contains roughly 90% of the geologic names found in the most recent listing of USGS-approved geologic names (published in 1996 as USGS Digital Data Series DDS-6, revision 3) and is estimated to contain roughly 75% of all geologic names in the United States. Prior to loading into GEOLEX, the information on DDS-6 was consolidated, revised, and error-corrected. In the past year, work focused on resolving name conflicts and adding reference summary and other information for each entry. Work remaining includes incorporating geologic names not found on DDS-6 but recorded in the geologic names card catalog at USGS Headquarters, and incorporating names approved by the State geological surveys but not yet in the USGS records. GEOLEX is intended to be the comprehensive, authoritative listing of approved geologic names, and is available as a resource for geologic mappers nationwide. Many state geological surveys have been registering new geologic names with the USGS for decades, and are encouraged to continue under GEOLEX, through a Web-based application form that will be introduced later this year.

Geologic Mapping in Progress Database
To provide users with information about current mapping activities at 1:24,000- and 1:100,000-scale (1:63,360- and 1:250,000-scale in Alaska), a Geologic Mapping in Progress Database was developed and contains projects active in 1998. The database will be updated later this year, and a publication prepared that explains its content.


Most efforts related to phase two have been directed toward the development of standards and guidelines needed to help the USGS and state geological surveys more efficiently produce digital geologic maps, and to produce those maps in a more standardized and common format among the various map-producing agencies. Significant progress has been made toward developing some of these standards and guidelines, and to providing map catalog users with access to online products.

Standards Development
The following summaries concern activities of the AASG/USGS Standards Working Groups and their successors. General information about the Working Groups, and details of their activities, are available at

Geologic Map Symbolization
A draft standard for geologic map line and point symbology and map patterns and colors, published in a USGS Open-File Report in 1995, was in 1996 reviewed by the AASG, USGS, and Federal Geographic Data Committee (FGDC). It was revised by the NGMDB project team and members of the USGS Western Region Publications Group and was circulated for internal review in late 1997. The revised draft then was prepared as a proposed Federal standard, for consideration by the FGDC. The draft was, in late 1999 through early 2000, considered and approved for public review by the FGDC and its Geologic Data Subcommittee. The document was released for public comment within the period May 19 through September 15, 2000 (see for the document and information about the review process). This standard is described in some detail in a separate paper in these Proceedings (Soller and Lindquist).

Digital Mapping
The Data Capture Working Group has coordinated four annual "Digital Mapping Techniques" workshops for state, federal, and Canadian geologists, cartographers, and managers. These meetings have been highly successful, and have resulted in adoption within agencies of new, more efficient techniques for digital map preparation, analysis, and production. The most recent workshop, held in Lexington, Kentucky, and hosted by the Kentucky Geological Survey, was attended by 98 representatives of 41 state, federal, and Canadian agencies and private companies. The workshop proceedings are published (Soller, 1997, 1998, 1999, and this volume) and served on-line (;;; and 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) led development of the USGS policy "Publication Requirements for Digital Map Products" (enacted May 24, 1999). A less USGS-specific version of this document was developed by the AASG/USGS Data Information Exchange Working Group and presented for technical review at a special session of the Digital Mapping Techniques '99 workshop (Soller and others, 1999). The revised document (entitled "Proposed Guidelines for Inclusion of Digital Map Products in the National Geologic Map Database") is now under review by the AASG Digital Geologic Mapping Committee for consideration as a guideline for newly-produced maps available through the NGMDB.

The Metadata Working Group developed its final report in 1998. The report provides guidance on the creation and management of well-structured formal metadata for digital maps (see The report contains links to metadata-creation tools and general discussions of metadata concepts (see, for example, the metadata-creation tools, "Metadata in Plain Language" and other helpful information at

Geologic Map Data Model
State and USGS collaborators on the NGMDB continue to serve as representatives to the North American Data Model Steering Committee (NADMSC), assisting in the process of developing, refining, and testing the North American Geologic Map Data Model. The NADMSC has now formed various technical teams to conduct specific tasks within a one-year period, and longer time-frames. If interested, please visit the NADMSC web site, More information is provided in a separate paper in these Proceedings.

Access to Online Products
Through searches of the NGMDB map catalog, users now can be directed to web sites for perusal of online products. This enhancement is now available for USGS products served on USGS Regional Publications Servers, and for metadata served on the USGS Clearinghouse node. At this time, more than 330 links exist to online map products and their metadata.


Separate discussions of 1) the public review of the geologic map symbolization standard; 2) the NGMDB Phase 3 activities; 3) the NGMDB Geologic Names Lexicon; and 4) the North American Geologic Map Data Model are available in these Proceedings. Please also refer to the NGMDB project information web site,, for more current information.

The authors thank the members of the NGMDB project staff and collaborators for their enthusiastic and expert support, without which the project would not be successful. In particular, we thank: Ed Pfeifer, Alex Acosta, Jim Mathews, Dennis McMacken, Chris Isbell, and Jana Ruhlman (USGS, Flagstaff, AZ; Website and database management), Nancy Blair and Chuck Mayfield (USGS Library; map catalog content), Nancy Stamm and Bruce Wardlaw (USGS; Geolex database), and John Sutter (USGS; Geologic Mapping in Progress database).


Soller, D.R., editor, 1999, Digital Mapping Techniques '99 -- Workshop proceedings: U.S. Geological Survey Open-file Report 99-386, 216 p.,

Soller, D.R., editor, 1998, Digital Mapping Techniques '98 -- Workshop Proceedings: U.S. Geological Survey Open-File Report 98-487, 134 p.

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., 1999a, Building the National Geologic Map Database: Progress and challenges, in Derksen, C.R.M, and Manson, C.J., editors, Accreting the continent's collections: Geoscience Information Society Proceedings, v. 29, p. 47-55,

Soller, D.R., and Berg, T.M., 1999b, The National Geologic Map Database--A progress report, in Soller, D.R., editor, Digital Mapping Techniques '99 -- Workshop proceedings: U.S. Geological Survey Open-file Report 99-386, p. 31-34,

Soller, D.R., and Berg, T.M., 1998, Progress Toward Development of the National Geologic Map Database, in Soller, D.R., editor, Digital Mapping Techniques '98 -- Workshop proceedings: U.S. Geological Survey Open-file Report 98-487, p. 37-39,

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

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., Duncan, Ian, Ellis, Gene, Giglierano, Jim, and Hess, Ron, 1999, Proposed Guidelines for Inclusion of Digital Map Products in the National Geologic Map Database, in D.R. Soller, ed., Digital Mapping Techniques '99 -- Workshop Proceedings: U.S. Geological Survey Open-File Report 99-386, p. 35-38,

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