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Digital Mapping Techniques '01 -- Workshop Proceedings
U.S. Geological Survey Open-File Report 01-223

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), in cooperation with the Association of American State Geologists (AASG) 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 requires 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 includes a comprehensive, searchable catalog of all geoscience maps in the United States, whether in either paper or digital format. The Mapping Act stipulates that the NGMDB will be built to address societal needs, hence this map catalog is designed for use by a wide variety of people, from private citizens to professional geologists. Figure 1a shows how the map catalog can be used to find a particular map showing the geology beneath a user's home. Upon searching the NGMDB catalog and identifying the needed map(s), the user is linked to the map data, the metadata, or to the appropriate organization for information about how to purchase the map. (The organization could be a participating state or federal agency, association, university, or private company.) The map catalog presently is 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.

Part 1 of a diagram showing how a user might navigate the NGMDB map catalog, Geolex, the Paleontology database, and the online map database

Figure 1A. Diagram showing how a user might navigate the NGMDB map catalog, Geolex, the Paleontology database, and the online map database. The user, interested in knowing something about the geology beneath their house, queries the Map Catalog, which returns a hit list of possibly useful maps. The user selects a map entry for more information and, from the Product Description Page, chooses to either buy the map, view and download it, or inspect the metadata. The dark arrow toward the bottom of the figure points toward the online map database (figure 1b).

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 (Soller and others). Some functions of the planned online database, and its links to databases developed under Phase 1, are shown in Figure 1b.

Part 2 of a diagram showing how a user might navigate the NGMDB map catalog, Geolex, the Paleontology database, and the online map database

Figure 1B. Diagram showing how a user might navigate the NGMDB map catalog, Geolex, the Paleontology database, and the online map database. The user now queries the online map database. (Note: the paths along these queries are shown as dashed lines, to indicate planned development.) From the initial display showing the geology of the area surrounding their house, the user might choose to reclassify those units in order to derive a map showing engineering properties, or query the geologic data in concert with external databases (here, an oil and gas database). Further, the user might be interested in the history of a particular geologic name, or the availability of fossils.

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, 1999b, and 2000). At the Digital Mapping Techniques '98 through '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-2000. 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). At the time of this conference, the catalog contained a record for each of nearly 38,500 map products. Essentially all USGS maps have been recorded in the catalog, and emphasis has now shifted to assisting the state geological surveys to enter all their maps and related maps (e.g., University theses) into the catalog. By the date of the DMT'01 meeting, geological surveys in 27 states were entering map records, as well as one University (Stanford); participation is now significantly greater than in the past. Since the time when essentially all USGS maps were entered into the map catalog, Web usage statistics indicate 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.

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 this practice under GEOLEX, through a Web-based application form.

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 is maintained. This database is available at MapProgress_home.html.


The NGMDB project has now begun to design and develop a national paleontology database (see Wardlaw and others, in these Proceedings). Our general plan is to build prototypes of this database in areas where geologic mapping is underway, so that we can work with mapping projects to design a database useful to science as well as to the public.


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 itself and for information about the review process). This draft standard is described in some detail in Soller and Lindquist (2000). With assistance from a newly-formed standing committee to oversee resolution of review comments and long-term maintenance of the standard, the document is being revised for 2002 submittal to FGDC, for discussion and adoption as a Federal standard.

Digital Mapping

The Data Capture Working Group has coordinated four annual "Digital Mapping Techniques" workshops for state, federal, and Canadian geologists, cartographers, managers, and industry partners. 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 Tuscaloosa, Alabama, and hosted by the Geological Survey of Alabama, was attended by approximately 110 representatives of 48 state, federal, and Canadian agencies and private companies. The workshop proceedings are published (Soller, 1997, 1998, 1999, 2000, and in this volume) and served on-line at (;;,, and Published 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 digital maps compiled under support of the STATEMAP component of the National Cooperative Geologic Mapping Program and 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 http:// standards/metadata/metaWG.html). 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 by the NADMSC in these Proceedings.

Access to Online Products

As standards are developed under Phase Two and via other mechanisms, the products released by geological surveys increasingly are standardized in format and content. A principal goal of Phase Two is to provide links from the Map Catalog to the more standardized of these products. Through searches of the NGMDB Map Catalog, users are directed to web sites for perusal of selected online products. This feature of the Map Catalog is now available for USGS products served on USGS Regional Publications Servers, and for metadata served on the USGS Clearinghouse node. At the time of this meeting, more than 500 links exist to online map products and their metadata.


Over the past few decades, significant advances in computer technology now permit complex spatial information to be stored, managed, and analyzed to the satisfaction of a growing number of geoscientists. At the beginning of the NGMDB project, we judged that computer-based mapping was not a sufficiently mature discipline to permit us to develop an online database. Further, technology for display and query of complex spatial information on the Web was in its infancy, and hence was not seriously considered by the NGMDB project as a viable means of delivering useful information to the general public. Now, six years after the project's inception, there exists sufficient digital geologic map data, sufficient convergence on standard data formats, data models, digital mapping practices, and field data capture techniques, and sufficient technological advances in Internet delivery of spatial information to warrant a research effort aimed at building a prototype, online National Geologic Map Database. To design an online database, project personnel have held numerous discussions with geoscientists and the general public, to gauge interest in an online database, and to define its scope. Based on these discussions, it is clear that this database should be:
  1. built from edge-matched geologic maps at various scales,
  2. managed and accessed as a coherent body of map information, not just as a set of discrete map products,
  3. updated by mappers and/or a committee, "on the fly" when new information becomes available (i.e., a "living" database),
  4. standardized, adhering to a standard data model and with standard scientific terminology, and
  5. available to users via Internet browsers and common GIS tools (e.g., ArcExplorer).
NGMDB project has begun a series of prototypes designed to build this online, "living" database; an introduction to the design approach is given in Soller and others (2000). In 1999, we designed some basic requirements for a prototype geologic map database, and tested our concepts using some newly-developed digital data for the Greater Yellowstone Area of Wyoming and Montana (Wahl and others, 2000). That first prototype was presented for discussion at the Geological Society of America Annual Meeting, in October, 1999. The prototype was well-received, and plans were begun for a second prototype, with a more complex set of tasks. That prototype, conducted in cooperation with the Kentucky Geological Survey, is summarized in Soller and others (this volume). We anticipate further prototypes that will advance our understanding of the technical and management challenges to be addressed in development of the operational system.

The online map database is being designed to integrate with other databases developed under this project. For example, a user accessing the online map database might identify a map unit of interest, and then want to purchase or download the original, published map product, or inquire about fossils found within that unit or the history of the unit's geologic name. These user questions exploit the power and flexibility of databases, and we anticipate building into the system the functionality diagrammed in figure 2. As another example of the interaction of the various NGMDB phases, this diagram shows that a user might access the Map Catalog and identify a map of interest; the user might then purchase the map or link to a map server where the product can be downloaded. In the latter case, the arrow passing through "Standards Development" indicates that the NGMDB project's standards development activities affect the content and format of products served.

Figure 2. Diagram showing user access to the various components of the National Geologic Map Database (NGMDB) project, and to related external databases and services. The three project phases are shown, and the relations among them. Dashed arrows indicate planned relations.


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, Dennis McMacken, Jana Ruhlman, and Michael Gishey (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).


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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., of98-487/.

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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, of98-487/soller2.html.

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., Berg, T.M., and Wahl, Ron, 2000, Developing the National Geologic Map Database, Phase 3 - An Online, "Living" Database of Map Information: Digital Mapping Techniques '00 - Workshop Proceedings: U.S. Geological Survey Open-File Report 00-325, p. 49-52,

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,

Soller, D.R., and Lindquist, Taryn, 2000, Development and Public Review of the Draft "Digital Cartographic Standard for Geologic Map Symbolization", in D.R. Soller, ed., Digital Mapping Techniques '00 - Workshop Proceedings: U.S. Geological Survey Open-File Report 00-325, p. 43-47,

Wahl, R.R., Soller, D.R., and Yeldell, Steven, 2000, Prototype Implementation of the NADMSC Draft Standard Data Model, Greater Yellowstone Area, in D.R. Soller, ed., Digital Mapping Techniques '00 - Workshop Proceedings: U.S. Geological Survey Open-File Report 00-325, p. 57-63,

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