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

Progress Toward Development of a Standard Geologic Map Data Model

By David R. Soller,1 Boyan Brodaric,2 Jordan Hastings,3 Bruce R. Johnson,4 Gary L. Raines,5 and Ronald R. Wahl6

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

2Geological Survey of Canada

3University of Nevada, Reno

4U.S. Geological Survey

5U.S. Geological Survey

6U.S. Geological Survey

A geologic map data model addresses the concepts inherent in a geologic map, and how the information on such a map (including the map legend and unit descriptions) can be organized in a set of computer files. Whether or not the geologist formally recognizes it, each geologic map they produce, in paper or digital format, is supported by a data model. Whenever they gather geologic information, interpret it, and publish a geologic map, they have used a data model to organize their thoughts and information on the map. Attempts to standardize the organization and syntax of these map data models are worthwhile, helping the geoscience community to organize its thinking about what is contained on a geologic map, and increasing the utility of the maps. Scientists and the general public who use a GIS commonly obtain digital maps from various organizations and integrate them to address scientific or societal issues. Unless geologic maps are widely available in a standard format, their integration with other map themes and, therefore, their utility for addressing such issues is limited.

To propose a standard geologic map data model, in 1996 the USGS and the AASG formed the Geologic Map Data Model Working Group. The Working Group is composed of members of the USGS, the State Geological Surveys, and the Geological Survey of Canada. Although initiated by the requirements for a National Geologic Map Database (NGMDB) (see the project's Web site at, the Group intended to propose a model that will be applicable, and acceptable, to the broader geoscience community. Following numerous presentations, discussions, and progress reports (for example, Raines and others, 1997), in October, 1997, a report describing the model was posted to the NGMDB project's Web site for public comment.

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 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 are invited to evaluate them, and to help us develop the prototype into a community standard that will serve both the scientist and general public.


Raines, G.L., Brodaric, Boyan, and Johnson, B.R., 1997, Progress report -- Digital geologic map data model, in David R. Soller, D.R., editor, 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.

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Last updated 10.07.98