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

Developing the National Geologic Map Database, Phase 3 -- An Online, "Living" Database of Map Information

By David R. Soller1, Thomas M. Berg2, and Ron Wahl3

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
  3U.S. Geological Survey
Box 25046, Denver Federal Center, MS 913
Denver, Co 80225
Telephone: (303) 236-1320
Fax: (303) 236-0214

The provisions of the Geologic Mapping Act of 1992 and its reauthorizations in 1997 and 1999 (PL106-148) require the U.S. Geological Survey (USGS) to design and build a National Geologic Map Database (NGMDB), with the assistance of the state geological surveys and other entities participating in the National Cooperative Geologic Mapping Program. After discussion among the principal architects of the NGMDB, a general plan for its initial design and evolution was proposed (Soller and Berg, 1995); minor updates to the plan, enhancements, and progress reports have been available yearly since 1997 (Soller and Berg, 1997, 1998, 1999a, 1999b, and this volume).

The NGMDB design identifies three phases to the project; these phases are complementary in nature. Because many maps are not yet in digital form and because many organizations produce and distribute geologic maps, it was decided to first identify and catalog all geoscience maps in the United States, in either paper or digital format. This first phase, a searchable map catalog, is the most fundamental aspect of the NGMDB; it enables users to identify whether a map has been produced for their area and/or theme of interest. 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. 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.

Although these activities produce valuable information for the public and the geoscience community, to most of us the "National Geologic Map Database" brings to mind the image of an online database containing geologic map information that can be queried, customized for display, and downloaded. Further, the map information in the database would be a coherent whole composed of the best information compiled from various map sources. The database would be updated as new maps are published and so could be termed a "living" database. Work on the third phase has begun, and is the subject of this paper.


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, five years after the project's inception, there exists sufficient digital geologic map data, sufficient convergence on standard data formats, data models, and digital mapping practices, 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, the project has 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,
  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).
Compiling a "Living" Database
The United States is, of course, rarely mapped as a single entity. Instead, the U.S. is covered with a "patchwork quilt" of geologic maps at various scales. These maps range mostly from 1:24,000-scale to more than 1:1,000,000-scale. Of these maps, those of most recent vintage and greatest detail tend to be favored for application to societal issues. However, only at the most regional scale do geologic maps cover any appreciably contiguous area. The challenge in utilizing the existing stock of geologic maps for societal issues lies in the necessary compromise between map "quality" and areal coverage -- those maps of highest societal utility tend to be the most modern and detailed maps; for most areas, these maps are unavailable and so older, less detailed maps must be used instead. However, for many scientific uses, such as regional, synoptic studies of large-scale earth science trends and societal issues, more regional mapping is preferred.

Because of these realities, a geologic map database must be comprehensive in its content, providing access to all available geologic maps regardless of scale. These maps should be made available in several forms:

Implicit in building such a database is the availability of sufficient geologic map information in digital form. Because only a fraction of published maps are now in digital form, the vast collection of published paper maps must be prioritized for conversion to digital form. In the coming years, significant effort will be needed for this conversion activity.
Standards and Guidelines
The compilation of many maps into a coherent whole will be difficult if each source map uses different terminology for describing the stratigraphy and characteristics of the geologic units. If each map was organized differently in digital form, rather than using a standard data model, the integration of data into a coherent whole will be further complicated. The NGMDB project has, for several years therefore, been engaged in helping to develop a set of standards and guidelines for digital geologic maps. Information on these standards- and guidelines-development activities can be found elsewhere in this volume and at the project website, Within the past year, these standards and guidelines became sufficiently mature to justify research and development of a prototype national database, as described below.

Public Access to the Database

The National Geologic Mapping Act and its reauthorizations (see the Act at stipulates that the NGMDB will be developed as a resource for application to societal issues. Public access to, and use of, the online map database is therefore a high priority. Emerging technology for Web-based information delivery offers the significant promise of exposing ever-greater numbers of people to databases such as the NGMDB, with the expectation that they will use the geologic information to address societal and personal issues. However, most Internet users, and the general public, are provided with overwhelming amounts of information, and face the attendant challenges of learning the new tools, methods, and thought processes needed to access and use that information. In short, people are confronted with a bewildering array of daily choices and challenges. As a result, there is an understandable reluctance to learn new ways to access information.

The public will be most likely to use an information delivery system that does not require new software or plug-ins, significant bandwidth, or training. With this in mind, we intend for public access to the NGMDB to occur via commonly-used tools (e.g., web browsers) that do not require extra plug-ins or training to use. In the short term, however, as the prototype database is under development, our emphasis will be develop the "back-end" of the database, the data-management system and the collection of standardized geologic map information. When the system approaches sufficient maturity for the public to use, the project then will design the software interface, or adopt an existing or agency-mandated interface, to allow public access to the online database.


Translating the concepts outlined above into a useful database will require that we: These requirements are now being addressed. As noted above, the geoscience community has begun to converge on some accepted standards and guidelines for digital geologic maps. In 1999, we designed some basic requirements for a prototype geologic map database, and tested our concepts usings some newly-developed digital data for the Greater Yellowstone Area (Wyoming and Montana) (Wahl and others, this volume). 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.

Plans for the Second Prototype
Following a series of meetings in late 1999 between the USGS, the Kentucky Geological Survey (KGS), and representatives of various state constituency groups and vendors, the second prototype was designed. In 2000, funds were secured, contracts were written, and the work began in mid-year. This prototype will address a limited number of objectives, because the goal is not to build a fully-functional online NGMDB; rather, the goal is to develop a firm foundation upon which subsequent prototypes are based and which will, eventually, evolve into the online, "living" NGMDB. This prototype's objectives are to: When the prototype's objectives are met, we will provide opportunities for discussion and comment, through public meetings.


Through this prototype and, hopefully, its successors, the agencies collaborating on the NGMDB will have the opportunity to evaluate the various approaches to serving their map data, both independently and through the NGMDB. In fact, this prototyping process is not just concerned with a set of technical issues -- a significant outcome will be a clearer understanding of the opportunities and challenges in collaboratively building a database whose ownership and infrastructure is shared by numerous agencies. This complex issue will receive careful attention throughout the prototypes, which are designed to explore the nature of the relationship among the NGMDB collaborators.

Finally, we draw attention to another significant, non-technical, aspect of the prototypes -- if the concepts here outlined are to be adopted, and a national database created, the system by which scientists are rewarded and promoted will require significant change. Scientists at the geological surveys are evaluated for promotion, and rightly so, by measures of their significant contributions to the science and to society. Historically, the principal measure is the publication record. Development of a national database will require significant scientific contributions from many scientists, but each contribution likely would not generate a discrete publication attributable to a scientist. Rather, the result would be an improved national database of geologic map information to which a scientist contributed. That contribution may be a significantly redefined stratigraphy or set of geologic contacts for an area, but how would that contribution be evaluated? Clearly, agencies will need to evaluate scientists based on an expanded set of criteria that would include contributions to the body of information and knowledge maintained in a "living" database.


Anderson, W.H., Sparks, T.N., Patton, J.A., Yang, Xin-Yue, and Sergeant, R.E.,1999, Integration of Relational Geologic Databases and a Spatial Map Database in Kentucky, in D.R. Soller, Digital Mapping Techniques '99 -- Workshop Proceedings: U.S. Geological Survey Open-File Report 99-386, p.123-125,

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