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

Map Authorship and Citation Guidelines: Summary of a Discussion Session

By C.R. Berquist, Jr.,1 and David R. Soller2

1Virginia Division of Mineral Resources
c/o Department of Geology
College of William and Mary
P.O. Box 8795
Williamsburg, VA 23187
Telephone: (757) 221-2448
Fax: (757) 221-2093
    2U.S. Geological Survey
908 National Center
Reston, VA 20192
Telephone: (703) 648-6907
Fax: (703) 648-6937


Among the geological surveys there exist many approaches to determining authorship credit and citation format for geologic maps, digital geologic maps, and associated digital data bases. Progress has been made toward understanding this complex issue, through discussions at many venues, including previous Digital Mapping Techniques (DMT) workshops. Berquist (1999) and Richards (2000) suggested authorship and citation policies and formats which provoked discussion and debate among the community of geologists, cartographers, earth-science editors, and librarians. Continuing the effort to clarify (if not resolve) this topic, an open discussion at DMT'01 was devoted to Map Authorship and Citation Guidelines. The content and results of this session are provided here.

Clearly, there are different philosophies on how to assign credit for geologic map products. For two of the major authorship/credit issues faced by agencies, here are some rather conflicting views expressed in the discussion session at last year's DMT workshop:

"if you make a contribution, including GIS work, then you're an author"
"only the mappers and regional stratigraphers/compilers should be authors"

"the database is part of the map (image)"
"the database is a product separate from the map (image)"

Resolution of those issues, as outlined below, is the purview of each agency and its mapping projects. This year's DMT discussion session was designed to explore common ground and common solutions to the issues, in the hope that good ideas developed by any of the geological surveys could be used by the entire community. We intentionally avoided discussion of criteria that may define the inclusion and ranking of individuals as authors, because those details are the responsibility of the publishing agencies. Furthermore, the session did not address the manner in which various types of authorship, GIS, and cartographic credit are noted on the map itself. Instead, the session focused on citation format and content by defining several principal issues, then holding an open discussion of each issue and asking for a show of hands by participants to establish the generalized degree of acceptance of each issue.

The session began with a review of previous work. In our session introduction, we synthesized our thoughts and those of other geological survey personnel who have shared information with us during the past year. Included in that introduction was a brief overview of copyright and contracting issues that may have some bearing on the rationale for assigning authorship to map products. Although copyright and authorship do not have precisely the same meaning, it may be instructive to view the problems of authorship of digital products from the perspective of copyright (ownership). Facts (e.g., the information in a telephone book) cannot be copyrighted. However, the expression of facts (layout, color, graphics, symbology, etc.) can be copyrighted (Harris, 1998). Indeed, some localities have more than one telephone book, each copyrighted by different organizations. In contrast, in geological science a greater sense of ownership is ascribed to the information — we certainly do not take someone else's map information, merely change the "expression" or display of that map, and then assign new authors to the new map. Geologist-authors of the original maps should retain authorship of subsequent map images, no matter how the maps are reproduced (scan or GIS image at any scale, projection, or color/symbology). The geologist created the map representation of rock descriptions and area/volume relationships of rock bodies and is responsible for the "science" behind the map (of course, eventually, revisions in scientific substance may warrant changes in authorship).

This viewpoint on authorship would seem to contradict the legal notion that when the "expression" of facts are changed, new ownership or copyright (and therefore new authorship) is possible. The information on geologic maps is, however, largely interpretive, not strictly factual, hence the science's rationale for retaining the source lineage of information in subsequent map representations and products. Despite this rationale, in the legal arena, published geologic maps may be regarded as legitimate factual information. It may therefore be prudent to regard our geologic maps as subject to legal definitions of fact.

The advent of GIS and digital map production techniques has introduced a significant complication to the copyright issues noted above. When digitizing a geologic map to create a published map product, the spatial data files in one sense may be considered comparable to an intermediate product of older map production technology (the scribe coats and acetate stickups). However, these files are now a desired end-product in themselves because they form the basis for map databases available for use in a GIS. If the map digitizing work is performed under contract, a contract generally should address copyright issues for products created under that agreement. This is prudent because in some circumstances these map files can be claimed for copyright (owned) by the contractor.

The legal differentiation of map image from map database files connotes the need to identify the responsible authors of each product. In many cases, authorship would be the same for both products. However, given the legal implications, this should not be assumed without due consideration of how the files were created, and whether their content differs from the information shown on the published map.

During both the pre-digital and the modern digital process of map production, errors that occur on preliminary, author-submitted maps were corrected and/or supplemented by errors introduced during cartographic preparation of the final, published map. Individuals who created the printing negatives (in the pre-digital age) or the digital data set are capable of omitting information, inserting incorrect information, and making errors in scribing or digitizing lines and other features. Before maps were digitally produced, these errors were an accepted part of the process, and the cartographer was not assigned any formal responsibility for their role in the final product.

How then can it be argued that the preparers of the digital map files, the GIS-compatible map databases, may in some cases warrant designation of formal responsibility for the product and, hence, shared authorship? We believe the answer is simply this: if the map database is published or released by the agency to the public, both the author's and the agency's authority and reputation are implicitly conveyed with the product. In contrast, pre-digital cartographic materials and digital files used solely to print a map are merely part of the map production process; hence they are not referenceable products. Also, information in databases may not be the same in structure, content, or use to that shown on source maps; for example, the difference between a map unit description on a printed map (or field sheet) and the equivalent information in a database (which may be derived from dissection of the map unit description and parsing that information into database fields, a process that may involve insight and interpretations not formally shown on the published map or field sheet). Further, on typical geologic maps, the location of geologic information (contacts, structure measurements, etc.) are located relative to topographic and cultural features on the base map. Once the geologic information is captured digitally, the location of each geologic feature becomes absolute (in some numeric coordinate system) and always will carry some new error, introduced by the capture process (e.g., georeferencing the source map). The digitized geologic information in a database now "floats in space" and is no longer explicitly tied or attached to the original topographic base upon which the field information was compiled. As a result, the geologic database (GIS) information becomes in some measure different from the source geologic map information. In our world of increasing litigation, agencies of course are now carefully considering if and how the content of each map and associated database product may differ, and assigning authorship credit and responsibility accordingly.


This paper is intended only to provide a summary of ideas presented at the discussion session and a brief and admittedly subjective record of the participant's reactions. This paper is not a formally proposed guideline derived by broad debate and consensus — it merely contains some citation formats that we propose may be useful. The issue of map authorship credit and responsibility, as noted above, was not the focus of the discussion session. These suggested formats were discussed but not reviewed and approved by the discussion participants. Although many of the ideas evolved from examples and discussions shared by our colleagues in other geological surveys, the responsibility for the proposal's shortcomings lie with the authors of this paper. It is hoped that these ideas, which represent in part a synthesis of previous work, may prove useful to geological surveys and to the geoscience community, as we all strive to protect and realistically portray the origin of each published map product.


As a group, the DMT'01 participants recognized that the authorship and citation issue is complex, and that discussion has not sufficiently matured to encourage all organizations to agree to a single standard (and such may never be the case). However, the session explored the possibility that interagency consensus could be reached on certain basic issues. These are explored below as they were presented in the discussion session.

Who Should Author a Geologic Map Product?

Each agency must control the content of its products, and this discussion session was not intended to prescribe a uniform approach to how map authors are determined. Geologic mapping is a rigorous intellectual and physical activity, and the people involved deserve appropriate credit for their contributions to the science and to society. In part because of technological advances that promote conversion of published maps to digital format, a product may have an extensive lineage of contributors and source materials, and there exist among the geological surveys many approaches to determining who should receive credit.

Discussion participants generally agreed with this position.

Should a Suggested Citation be Provided on Each Map?

The discussion session addressed the content and format of the map citation. It did not address the manner in which various types of authorship, GIS, and cartographic credit are noted on the map. Specifically because the authorship, other credit, title, and citation standards may be confusing to our users, we strongly suggested that the suggested citation be explicitly given, directly below and clearly related to the map collar information regarding title, date, authorship, and other credits (as per Berquist, 1999). The following might be placed on the map, to draw attention to the citation:

"When referring to this map, the following citation should be used:"
(insert citation, in agency's adopted format, here)

In response to this suggestion, the discussion participants voted a clear "yes".

New Mapping vs. Existing Maps

As a first step toward defining citation formats, let us assume that map publications may fundamentally be classified as:

  1. products based on new mapping — In this case, field work and/or compilation has produced a body of scientific information that can be considered significantly different from pre-existing mapping. Of significance, it is likely that all persons who made a contribution to the final product (geologist and GIS/cartography staff) will be available for planning, discussion, and completion of the work, and are capable of reaching a mutually agreeable decision on the title and authorship.
  2. products based on published mapping — In this case, previously published map(s) are recompiled into a new product. The original geologist author may not be available for consultation and inclusion in the process of digital conversion and/or a geologic revision. In this situation, the authorship criteria is subject to a hierarchy and variety of agency rules involving the amount and/or significance of revisions.

The discussion participants clearly agreed that these are two fundamentally different types of publications.

Is a Map Database a Product, Separate from a Map?

We then proposed that there exist two fundamental products in a digital map publication, and that these products are closely related:

  1. the geologic database, which contains all spatial and attribute information for the geology of the map area. Included in this database should be the information needed to represent the author's preferred cartographic depiction of the geology.
  2. the image (in paper or electronic format) generated by the author's preferred cartographic depiction of the geology.

Should we recognize the existence of both of these two different, but related products? The decision affects how these map products are defined and managed by the agency, and how they are cited by the public. It is certainly debatable whether the map database is a product fundamentally different from its many possible physical representations (e.g., a paper map showing the geologist's preferred depiction of the geology). Some geologists and agencies consider the database and the paper map to be the same product. Is that a valid contention? In some cases this may be essentially correct, but in other cases the database structure and content may contain more complexity than can be shown on the paper map. Furthermore, although the map and database may, upon initial release, be two components of the same product, in time there may be revisions to the database necessitated by error-checking and minor additions that will cause the content of the printed map (inherently a static product) and the map database (potentially a dynamic product) to diverge. Prior to designation of the map database as a fundamentally new product (e.g., upon recompilation of the area's geology), successive versions of the database may become significantly different from the printed map. Unless the agency identifies two distinct but related products, it will be a challenged to manage a single product that may, over time, be comprised of two diverging manifestations.

This discussion session did not address the scientific content of the map and database, but merely sought to identify agency philosophy toward how its products are managed. As noted, it is our contention that a map image and its map database are two separate, but clearly related, products.

After lengthy discussion, the audience was almost evenly divided on this issue.


To illustrate and to provoke discussion on the various questions and issues noted above, we presented to the discussion participants some example citations (below). However, discussion on the above issues consumed most of the allotted session time, and so participant response to the content shown below could not be reasonably assessed. We hope that further discussion regarding these example citations may ensue, and evolve toward a set of common ideas or informal guidelines that might assist each geological survey and agency.

For purposes of map authorship and citation, the two classes of map product identified in the discussion session (i.e., existing maps and new mapping) can be treated quite differently. Simple examples of these two classes are given below. More complex cases, such as the anthologies discussed in Richard (2000), were not discussed here, but clearly are of significance to any robust agency policy.

I. Products Based on New Mapping

For products based on new mapping, the situation is relatively simple -- the mapping team should identify the contributions of the various team members (geologists, GIS specialists, cartographers, and, in some cases, database managers) and provide that information in the appropriate citation format. In some geological surveys, it is the policy for scientists alone to receive authorship credit on a new map. It was not our intent to debate this philosophy in the discussion session.

Here is the proposed suggested citation for a new map product (note that use of "Digital" in title is now generally agreed to be unnecessary since digital map production methods are now the norm). This citation is in common use today:

Doe, J.K., and Smith, A.B., 1999, Geologic map of the XYZ Quadrangle: The Geological Survey, Map X-123, scale 1:24,000.

If an agency recognizes two separate, related products -- paper map and geologic database -- then the proposed suggested citations would be:

Doe, J.K., and Smith, A.B., 1999, Geologic map of the XYZ Quadrangle: The Geological Survey, Map M-123 (Part A), scale 1:24,000.

Doe, J.K., Digits, C.D., and Smith, A.B., 1999, Geologic database of the XYZ Quadrangle, v.1.0: The Geological Survey, Map M-123 (Part B), ArcInfo Export file and dBase file, scale 1:24,000, available on CD ROM or <URL, if any>.

Note that the examples show the two products as part A and B of a single numbered map. An agency might just as readily choose to designate the products in separate series (e.g., printed and digital product series).

Is it necessary to cite the distribution media (e.g., "CDROM")? For the scientist, when citing a published work, it may be irrelevant. However, for purposes of cataloging and describing a published product for a library or publications sales office, we assume it will be necessary. Please note that the product title includes the database version number — it may be more appropriate to place this information and/or the time stamp toward the end of the citation.

Inclusion of additional author(s) in the database product indicates that skills in database design and GIS were deemed essential to the content and end-use of this product. That may not always be the case, and authorship decisions are, explicitly, the domain of the mapping project and agency.

From the above citations, we would expect that J.K. Doe played a responsible, significant, and active role in the creation of both the map and the database, since Doe is senior author on both publications.

In the example above, the map and the database contain fundamentally the same scientific information. Which should be cited? As noted by Steve Richard (Arizona Geological Survey, personal communication), the answer depends on how the information was used. For example:

II. Products Based on Published Mapping

This situation is more complex. Obviously, an existing product may have been: converted to digital format; adapted to fit a modern digital base map, new mapping paradigms, or newer adjacent geologic mapping; and/or recompiled. Because the original author(s) may not have participated in this process, authorship credit may be uncertain. For discussion purposes, we subdivided this category of products as follows:

  1. Raster Image of Published Map: When a paper map is scanned to create a raster image, the information content can be identical. Nevertheless, an agency may choose to catalog the image as a separate product, for reasons including:

    If the agency chooses to manage the image as a distinct product, then the following formats are suggested. Note that because this product is simply a scanned rendition of the previously published map, the original authorship should be retained intact. The map series identifier may, however, be different.

    Doe, J.K., and Smith, A.B., 2001, Geologic map of the XYZ Quadrangle [scan]: The Geological Survey, Map D-15, one Adobe Acrobat (PDF) file, scale 1:24,000, <URL, if any>.


    Doe, J.K., and Smith, A.B., 2001, Geologic map of the XYZ Quadrangle: The Geological Survey, Map D-15, [scan of Map M-123, published 1999], one Adobe Acrobat (PDF) file, scale 1:24,000, <URL, if any>.

    The discussion participants seemed to agree with this approach, but were divided as to whether the file type should be noted. The second citation may be preferred, as it provides more information on the original map product. Some participants noted that, in their agency, the scanned rendition of the map is not given a unique map series designation nor managed separately from the paper map.

  2. Geologic Map Based on Published Map: In some cases, the newly-released geologic map may be essentially unchanged from the original map; the map may have been converted to digital format, but without addition or revision of scientific content. In other cases, the original map may have been modified to fit a modern digital base map, or to adapt to new mapping paradigms, or to incorporate newer adjacent geologic mapping. Also, the original map may have been recompiled. These cases each should be treated differently. The proposed solution is a bit awkward perhaps, but retains full reference to the source map:

    1. the original map was unmodified — this case is analogous to II-A, above ("Raster image of published map"), because the product is a digital file from which a faithful rendition of the source map can be displayed or plotted. In this case, however, the file is derived from a vector-based digital map created with a CAD or GIS software package. The proposed suggested citation retains intact the original author list, modifies (i.e., "digitized from. . .") the title to reflect the fact that this is a new product, and appends the original, full citation:

      Doe, J.K., and Smith, A.B., 2001, Geologic map of the XYZ Quadrangle, digitized from Doe and Smith 1999 map: The Geological Survey, Map D-30, one Adobe Acrobat (PDF) file, scale 1:24,000, available on CDROM or <URL, if any> [digitized from Doe, J.K., and Smith, A.B., 1999, Geologic map of the XYZ Quadrangle: The Geological Survey, Map M-123, scale 1:24,000].

    2. the original map was modified — here, the digital file contains information that provides a display or plot derived from, but not identical to, the information content on the source map. In this case, the proposed suggested citation includes a new author list but in the title it retains intact the original author list (unless multiple authors, then "Doe and others"), modifies (i.e., "adapted from. . .") the title to reflect the fact that this is a new product, and appends the original, full citation:

      Smith, A.B., and Digits, C.D., 2001, Geologic map of the XYZ Quadrangle, adapted from Doe and Smith 1999 map: The Geological Survey, Map D-31, one Adobe Acrobat (PDF) file, scale 1:24,000, available on CDROM or <URL, if any> [adapted from Doe, J.K., and Smith, A.B., 1999, Geologic map of the XYZ Quadrangle: The Geological Survey, Map M-123, scale 1:24,000].

  3. Geologic Database Derived from Published Map: If a map database is created (as perhaps in II-B, above) from a published geologic map, the agency might choose to release it as a separate product, as discussed in this paper's introductory section. If so, this new product may or may not have the same author list as the source map. The proposed suggested citation includes ideas from section I and II-B-2, above:

    Digits, C.D., 2001, Geologic database of the XYZ Quadrangle (v.1.0), adapted from Doe and Smith 1999 map: The Geological Survey, Map D-45, ArcInfo Export file and dBase file, scale 1:24,000, available on CDROM or <URL, if any> [adapted from Doe, J.K., and Smith, A.B., 1999, Geologic map of the XYZ Quadrangle: The Geological Survey, Map M-123, scale 1:24,000].


Discussions on this subject tend to be lively. We anticipate that, in various formal and informal venues, the issues will be further debated. Certainly, we do not expect the ideas presented herein to survive intact during each agency's development of authorship and citation policies. However, we do hope that the DMT discussions will both support development of agency policies and perhaps draw the agencies toward a more common style and philosophy for authorship and citation format. Because policies that deal with products of computer technology are not well defined, it seems prudent or necessary that we, the community of informed and interested map producers and users, set the standards and conventions that would preserve the relationship of the geologist-authors to their product, the map image; we also should identify and preserve the appropriate authorship and/or credit for those professionals who are responsible for creating the database files.


Berquist Jr., C.R., 1999, Digital map production and publication by geological survey organizations; A proposal for authorship and citation guidelines, in Soller, D.R., ed., Digital Mapping Techniques '99–Workshop Proceedings: U.S. Geological Survey Open-File Report 99-386, p. 39-42,

Harris, L.E., 1998, Copyright Law Issues in Modern Cartography, in D.R. Fraser, ed., Policy Issues in Modern Cartography, Elsevier Science Ltd 1998, LCCN 98-25805.

Richard, S.M., 2000, Proposal for Authorship and Citation Guidelines for Geologic Data Sets and Map Images in the Era of Digital Publication, in Soller, D.R., ed., Digital Mapping Techniques '00–Workshop Proceedings: U.S. Geological Survey Open-File Report 00-325, p. 159-168,

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