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

Proposal for Authorship and Citation Guidelines for Geologic Data Sets and Map Images in the Era of Digital Publication

By Stephen M. Richard

Arizona Geological Survey
416 W. Congress #100
Tucson, AZ 85701
Telephone: (520) 770-3500
Fax: (520) 770-3505
e-mail: richard_steve@pop.state.az.us

INTRODUCTION

As more and more geologic data are released in digital form, new conventions for citation of sources are becoming necessary. Existing proposals for authorship guidelines have laid groundwork for new conventions (U.S. Geological Survey, 1995; Berquist, 1999). This proposal is an effort to formalize these conventions by clearly defining all terms and considering all paths between data collection and publication.

Geologic data originate as a set of observations made at particular spatial locations (field observations). Samples collected at particular locations may be subjected to more detailed analysis to supplement the field observations. These observations are interpreted to define the map units and locate boundaries that together constitute a geologic map. The geologic map constructed from these observations represents a model of some aspect of the earth in the area depicted. Depending on the nature of the geology, the experience of the geologist, and the goal of the data collection, the model that a geologic map represents may be as simple as the distribution of materials on the earth's surface, or as complex as the 3-dimensional structure of polydeformed metamorphic rocks. The person or persons who develop a model of a particular region of the earth by collecting observations, defining map units, and locating and interpreting faults and boundaries between the map units are the original authors of geologic data.

DEFINITIONS

A Geologic data set is a collection of map unit definitions, interpretations of the nature of the boundaries between the map units, locations of faults and boundaries between the map units defined, and descriptions (quantitative and qualitative) of the internal structure of the map units. Data set as used here is independent of the format of the data--it may be digital or analog. Geologic data sets built by the traditional geologic mapping approach outlined above typically start out as a collection of paper 'field sheets' and notes, which are assembled mechanically into geologic map images that represent the author's 'earth model' and data set. The geologic map may be accompanied by a report that adds information to the data set in the form of tabulated data, descriptive text and figures, and supplemental geologic map images. Using modern technology, it is now possible to build a data set directly into a digital database. A geologic data set is defined by:
  1. The conceptual model that defines the kinds of things that may be represented, how these things are related to each other, and rules that determine valid data sets.
  2. The region (area or volume) that is represented by the data set, referred to as its extent.
  3. The particular map units, boundary locations and interpretations, and quantitative or qualitative descriptions included in the data set.
The conceptual model is the data collector's abstraction of the geologic framework. Conceptual models evolve over time, both in the development of a single data set, and with the development of the science of geology. The concepts at the disposal of the data collector determine the sort of things that are observed. Maps of the Franciscan complex produced before the development of ideas about melange and accretionary wedges are quite different from maps produced after those concepts were developed. Different conceptual models might be applied to the same outcrop area depending on the interests of the data collector.

Consider the different approaches used to map surficial deposits, alteration zones, or bedrock geology. The science of geology is founded on a set of rules that reflect our understanding of the Earth. These include the establishment of relative age based on crosscutting relationships, and the laws of original horizontality and superposition for sedimentary rocks. The conceptual model for a geologic data set includes these widely accepted rules as well as more local rules based on understanding of the regional geology, and rules developed for the particular map area in the course of data collection. The geometry and topology of map unit boundaries and faults imply a geologic history based on these rules. A geologic data set is valid if the geologic history it implies is internally consistent, and if the material at any location in the modeled area or volume belongs to at least one map unit.

There are many approaches to collecting observations and developing an 'earth model' to build a geologic data set. The traditional, stereotypical approach is to take a paper topographic map or air photo, and walk around an area making observations, building a model of the geology as it is drawn on the base map. Another approach to developing an earth model might include studying core and cuttings from wells, well logs, and seismic lines, and drawing cross sections or structure maps on a particular boundary. Gravity and magnetic data may be collected and interpreted in terms of a set of 2 or 3-dimensional bodies of rock with particular physical properties. Remotely sensed data of a variety of sorts may be interpreted to define map units on a planetary surface and build an Earth (or Venus, or Mars...) model. All of these processes are analogous.

A single data set is based on a single data source, typically a mapping project under a single authorship. A compiled data set integrates information from multiple sources. The author of a compilation evaluates all the included data, and must resolve inconsistencies in the earth model(s) underlying the various sources. These discrepancies might include different locations of rock body boundaries, different definitions of mapping units, different levels of structural detail, different base maps, and emphasis on rocks of different ages or types (e.g. bedrock vs. surficial). Compilation may also require generalization of linework on source maps to be appropriate to the scale of the compilation being produced. A data anthology is a collection of data sets that have been aggregated in a single structure, but may have internal inconsistencies. A geologic data anthology might include compiled data sets with different compilers and data sources, and data sets with overlapping or coincident extents.

A geologic map image is a representation of a geologic data set for an area. The map image is defined by the map area extent, the map projection, a specification of the surface represented by the map, the geologic data used, the choice of symbols for geologic features, and the cultural and physiographic base map. The path from a geologic data set to a geologic map image requires selecting symbols to represent the distribution of the map units, the location and type of map unit boundaries and faults, and the location and relevant data for point observations (orientation measurements). These symbols are placed on a base map that represents the map area by means of a projection and some elevation model to represent topography on the mapped surface. The base map provides a visual reference frame to depict the spatial relationships between geologic features, and a means of physically locating the features depicted. Design of the base map is an important aspect of cartography. This definition of a map image makes no distinction between a standard geologic map (map surface = earth surface), a mine-level map (map surface = horizontal plane), or a cross section (map surface = vertical plane along section line).

A geologic map image may be published in a traditional paper form or as a digital file. For a traditional map printed on paper, a limited number of identical copies of the map exist, and modification of the map requires significant duplication of the effort made to produce the original map. Citations for such maps follow the established conventions (author, date, title, map series, publisher, scale, media). This map image is fixed by the design on the printing plates, and every copy of the map will be identical. A digital geologic map is a geologic map image published as a digital file that allows the map image to be viewed on a dynamic display (computer monitor, computer projection system, etc....) or reproduced on paper or other physical media (film, T-shirts...) by the user. Because the image is in a digital file, it may be printed in whole or in part, and may be printed at different scales. Depending on the file format, users may be able to modify elements of the cartography--change colors or symbols, hide some of the symbols, or even add new base map elements. A citation to a digital geologic map refers to the particular map image in the original digital file. The image may be printed or displayed at different scales, in whole or in part, with different colors or other cartographic modifications. If the image is modified to change the geologic interpretation represented, then a new map has been produced.

A digital geologic data set represents a geologic data set in a georeferenced form using a set of computer files. A digital geologic data set is defined by:

  1. The conceptual model that is the basis for the geologic data set (see discussion above).
  2. A logical data schema that is a mapping of the conceptual model underlying the geologic data set to data structures that can be represented by an automated system (e.g., relational tables).
  3. An implementation schema that defines the organization of data into files, the detailed structure of the files, and the representation of data in the files. The file format dictates the software and hardware systems that are compatible with the data.
  4. A projection that describes how the geographic location of features is specified.
  5. The data instances contained in the files.
  6. A set of definitions that specify the meaning of attributes applied to included data instances.
A citation to a digital data set refers to the particular combination of these components. If any of the components are modified, a new data set is created. Modifications might include mapping the logical schema from a relational data model to an object-oriented data model, importing the data into a software system that requires a different file format, changing the projection of the data, adding, deleting, or updating data instances, or updating aspects of the data classification.

A geoscience database system is a digital geologic data anthology along with tools for entering, updating, tracking, querying, and visualizing the data. Data visualizations commonly take the form of geologic maps, which are analogous to tabular reports generated from standard non-spatial databases. Other types of 'reports' that are useful include text summaries of rock unit definitions, and stereonet plots of orientation data from a particular area or map unit. The database may include tools for generating standard map visualizations from the data, based on an automated-cartography procedure, and standard map templates and symbol sets.

SUGGESTED AUTHORSHIP AND CITATION CONVENTIONS

A geologic data set may be published as geologic map images and text or as a digital data set. They are different representations of the same thing--an underlying collection of observations with an associated earth model. A citation to a geologic data set, whether represented as a map image or a digital data set, refers first and foremost to the underlying collection of observations and the associated earth model. In order for the citation to be meaningful as documentation, all of the components of the cited data set, as defined above, must be immutable. If deemed appropriate by mutual agreement of the authors, authorship may be expanded to include roles in addition to the intellectual origin of the geologic data set. For a map image, the authorship may be expanded to recognize contributions to the cartography. For digital data sets, the authorship may be expanded to recognize contributions to data editing and quality assurance if data conversion is required. Authorship recognizes essential contributions to the intellectual origin and accurate representation of a geologic data set.

In order to recognize the different sorts of geologic data sets, several terms are defined that should be included in document titles to clarify the nature of the represented data set.

Geologic map of... A single or compiled data set represented as a map image
Digital representation of... A digital map image in a vector file format, produced by data conversion from a physical original, and meant to reproduce the geologic data set
Spatial data for... A single or compiled data set represented as digital geologic data
Anthology A geologic data anthology
Scan A digital geologic map image in a raster file format that can be displayed to duplicate a map image on physical media.
View A digital geologic map image produced by a database query and automated cartographic procedures from a digital geologic data set or database.

Digital data sets and map images are subject to more frequent modification than their predecessor representations on paper. These modifications may include update by their originators, editing by other authors, and aggregation with other data. A compound form of citation is necessary that recognizes both the originator and the modifier(s) of digital geologic data sets. The compound citation first recognizes the current form of the data set representation, followed by a relation term to a source data set.

"adapted from..." is used to indicate derivation of a data set or a map image from a published map image when the product (data set or image) is meant to represent the same geologic data set as the original, but the map extent, cartographic design, or base map may be different.

"derived from..." is used to indicate derivation of a map image from a GIS spatial data set or database. Implies that the location of points and lines is equivalent to that in the database, and all polygons having the same classification in the database are symbolized with the same graphical element on the map image.

"based on..." is used to indicate derivation of a data set or map image from a published map image, but that minor changes have been made to the geologic data set. Derivative maps generated by tracing a map on physical media are always considered based on because the location of lines and points can not be reproduced exactly.

Other contributions may be prominently recognized in the title block of the map, but not included in the formal citation. Examples might include "Includes mapping by ..." for a compiled map, or "Data editing and conversion by..." for digital geologic data.

The process of constructing a digital geologic map image includes:

  1. Development of the underlying geologic data set: the geologic classification, location, and description of geologic features.
  2. Conversion to digital form if necessary.
  3. Selection of features to include in the map image.
  4. Cartographic design of map image, including base map design and feature symbolization.
The data conversion (step 2) is in many cases functionally equivalent to the role previously played by the drafting person, in which case acknowledgment is not necessary. Step 2 may include significant editing and error correction if it is done by a geologist, in which case the input should be recognized in printing on the map image ("Data conversion and editing by..."), or by inclusion in authorship (included in the map citation). Step 4 may be equivalent to the role of a technician if the cartography of a published map is to be reproduced as nearly as possible in a digital form, in which case acknowledgment is not necessary. New cartographic design involves significant input and understanding of the map content, and should be either acknowledged in printing on the map image ("Cartographic design by ...."), or be recognized by inclusion in the map authorship (included in the map citation).

Three kinds of authorship must be tracked for a digital geologic data set:

  1. Data schema authorship for the design and implementation of the data schema for the database.
  2. Data entry authorship for entry of information in the database, and verification of the accuracy of the data entered.
  3. Intellectual authorship for origination of the actual geologic data that are used to populate the data set.
Database schema design and implementation precede and are independent of the data entry phase, and should be documented in one or more stand-alone publications attributed to the appropriate author(s). Data entry typically involves a technician, who does the typing and digitizing, and an editor, who is responsible for the accuracy of the product. One or several persons may play these roles. For a single digital data set based on a single published or unpublished source (map or field notes and field sheets), the editing role simply involves comparison of the original data against the location and attribution of features in the data set. Neither the digitizing nor the editing role requires intellectual input of a specialized geologic nature. Data entry technicians should be identified and acknowledged. The data set editor could be listed as an author in the editor role. For a compiled digital data set that integrates information from multiple sources, the editor role requires reconciliation of sources at the boundaries between the maps, and correlation of the 'earth models' underlying the various source maps. In this case, the editor role is analogous to the 'compiler' of a map image based on various sources.

MAP IMAGE EXAMPLES

Each numbered case below discusses a particular set of circumstances for a published printed or electronic map image. Example citations to Virginia maps are based on examples in Berquist (1999), and are included to show how they fit into the scheme proposed here. As a rule, a citation for any geologic map image should clearly define the source of the underlying geologic data set, the display scale used for designing the cartographic composition, the publisher of the map, and the medium used to transport the image. For maps on physical media, this is typically sheet(s) of paper, and possibly an accompanying text. For digital images, the citation must specify the number and format of the file(s) that contain the map image and any associated text. The physical media (floppy disks, CDROM, DVD....) that contain the files is not essential, since the files can be copied between media, or may be transferred directly across a network.

1. Map image on a physical medium that represents a single data set. A fixed quantity of identical copies is produced in a single press run (traditional printed paper map). The map image is an original publication, produced under the direction of, or by, the same authorship as the geologic data set the map represents. The mechanics of producing the map image that is printed may be described in the map surround, and acknowledgement for persons contributing to the map production should be included as appropriate. Richard, S.M., and Spencer, J.E., 1997, Geologic Map of the North Butte Area, Central Arizona: Tucson, Arizona Geological Survey Open-File Report 97-4, 1 sheet, 15 pages, scale 1:24,000.

2. Map image on a physical medium that represents a compiled data set. A fixed quantity of identical copies is produced in a single press run (traditional printed paper map). The map image is an original publication, produced under the direction of, or by, the same authorship as the geologic data set the map represents. The mechanics of producing the map image that is printed may be described in the map surround, and acknowledgement for persons contributing to the map production should be included as appropriate. The map surround or accompanying text must include citations to sources of data. Richard, S.M., and Spencer, J.E., 1998, Compilation of geology of the Ray-Superior area, Pinal County, Arizona: Tucson, Arizona Geological Survey Open-File Report 98-13, 1 sheet, 35 pages, scale 1:24000. Spencer, J.E., compiler, 1995, Geologic Map of the Little Horn Mountains 30' by 60' Quadrangle, southwestern Arizona: Tucson, Arizona Geological Survey Open-File Report 95-1, 1 sheet, 10 pages, scale 1:100,000.

3. Map image with single authorship, represented as a picture in a raster-format file. The map image is identical to the source material that was scanned, within limits of scanning and display accuracy. Citation appends "[scan]" to the map title; the publisher and series identification remain the same; the medium description specifies the file format; and the scale is labeled 'map layout scale', which is the scale at which the original cartographic design was done, because the digital image may be displayed at widely-varying scales. A citation to such a map image for a map also published on a physical medium is specifically to the digital version of the map image, distinct from the original published version of the map. If the geologic data set represented by the map is being cited, the original map publication should be cited using the format of case one or two above. If the raster image is the only published form of the geologic map image, then the geologic data set it represents is always cited in this format.

Richard, S.M., and Spencer, J.E., 1997, Geologic Map of the North Butte Area, Central Arizona [scan]: Tucson, Arizona Geological Survey Open-File Report 97-4, 1 Adobe Acrobat (pdf) file, map layout scale 1:24000.

Doe, John, 1997, Geologic map of the Walker Quadrangle, Virginia [scan]: Richmond, Virginia Division of Mineral Resources Manuscript Map 97-3, 1 tagged image format (tif) file, map layout scale 1:24,000.

4. Map image is a digital, vector-format representation of a map published on physical medium. The map image produced is not identical to the original source, but it represents the same geologic data set. No digital geologic data set representing the same geologic data set is published. The process of producing vector data to represent the map requires tracing all lines and classifying the graphical objects produced (points, lines and polygons) to match the original. This is fundamentally different from scanning the map because of errors inherent in tracing, and the possibility of classification errors. In addition, the colors and symbols are unlikely to match the original exactly, and may be modified on purpose or by necessity. If the author of the original, physical map is not involved with production of the digital map image, the title of the digital map is constructed as "Digital representation of..." followed by the original title. A citation to such a map is specifically to the particular digital version of the map image, distinct from the original published version of the map. Thus, authorship of the digital representation indicates responsibility for the accuracy of the data conversion process. If the geologic data set represented by the map is being cited, the original map publication should be cited using the format of case one or two above. The medium description in the citation for a digital map indicates the file format of the digital representation. A scale is not necessary for the digital representation because it is specified in the citation to the published source.
Motiwala, P., 1998, Digital representation of Geologic Map of the North Butte Area, Central Arizona: Tucson, Arizona Geological Survey DI-999, 2 Adobe Acrobat files. Adapted from Richard, S.M. and Spencer, J.E., 1997, Geologic Map of the North Butte Area, Central Arizona: Tucson, Arizona Geological Survey Open-File Report 97-4,1 sheet, 15 pages, scale 1:24000.
If the authorship of the original physical map image is also responsible for production of a vector-format digital map image representing the same geologic data set, the title includes "Digital geologic map of..." followed by the same title as the physical map image. If deemed appropriate, other persons responsible for data conversion accuracy and digital cartography may be added to the author list, otherwise they should be acknowledged appropriately on the map surround. As in the case of a scanned map (case 3) the scale is labeled 'map layout scale', which is the scale at which the original cartographic design was done, because the digital image may be displayed at widely-varying scales.
Richard, S.M., Spencer, J.E., and Orr, T.R., 1999, Digital geologic map of the North Butte Area, Central Arizona: Tucson, Arizona Geological Survey Digital Information Series DI-999, 2 Adobe Acrobat (pdf) files, map layout scale 1:24000.

Doe, J., 1998, Digital geologic map of the Walkers quadrangle, Virginia: Richmond, Virginia Division of Mineral Resources Digital Publication DP-5, 1 encapsulated postscript (eps) file, map layout scale 1:24000.

If the vector-format digital map image is the original publication of the geologic data set, the map image is cited in the same fashion, with authorship determined by mutual consent of those involved. In this example, Rader and Gathright did the field work to produce the map, and produced the digital map image.
Rader, E.K., and Gathright, T.M., II, 1998, Digital geologic map of the Front Royal 30 by 60 minute quadrangle, Virginia: Richmond, Virginia Division of Mineral Resources Digital Publication DP-9, 1 encapsulated postscript (eps) file, map layout scale 1:100,000.
5. Map image modified from digital, vector-format representation of a published map image. The map image is modified from the original source by combining map units, deleting or adding some point data symbols, reinterpreting nature of boundaries between units, adjusting location of faults and contacts. With enough changes, this sort of modification eventually results in a compiled data set, in which case the citation would be that for a compiled map image (case 2 above), or a data anthology (case 9). This is a judgement call on the part of the producer of the derivative map.
Reynolds, S.J., 1999, Laramide igneous rocks in the North Butte Area, Central Arizona: Phoenix, Wide World of Maps, 1 sheet, scale 1:50000. Based on Richard, S.M., Spencer, J.E., and Orr, T.R., 1997, Digital Geologic Map of the North Butte Area, Central Arizona: Tucson, Arizona Geological Survey DI-999, 2 Adobe Acrobat (pdf) files, map layout scale 1:24000.
6. map image represents the same geologic data set as a published digital geologic data set by the same authorship. This differs from case 1, because the map image is digital, and from case 4 because digital data representing the same geologic data set are published. If only one version of the digital data set is published, and the digital geologic map image represents the same data set as the published digital data set, a relationship to the digital data set does not need to be included in the citation. The map image should always have a separate citation from the digital data set because one or the other might be updated independently.
Ferguson, C.A., and Enders, M.S., compilers, 2000, Geologic map and cross sections of the Clifton-Morenci area; Coronado Mountain, Mitchell Peak, Copperplate Gulch, and Clifton 7.5' quadrangles, Greenlee County, Arizona: Tucson, Arizona Geological Survey Digital Information Series DI-19, 1 Adobe Acrobat (pdf) file (3 plates with text), and other files, map layout scale 1:24,000.
If the digital data set is subject to updates, then a relationship to the particular instance of the data set used to generate the map image must be included in the citation. File format information for the underlying digital data set may be omitted for brevity.
Ferguson, C.A., and Enders, M.S., compilers, 2000, Geologic map and cross sections of the Clifton-Morenci area; Coronado Mountain, Mitchell Peak, Copperplate Gulch, and Clifton 7.5' quadrangles, Greenlee County, Arizona: Tucson, Arizona Geological Survey Digital Information Series DI-19, 1 Adobe Acrobat (pdf) file (3 plates with text), and other files, map layout scale 1:24,000. Derived from Ferguson, C.A., Enders, M.S., and Orr, T.R., 2000, Geologic Spatial Data for the Clifton-Morenci area, Greenlee County, Arizona (ver. 2.2): Tucson, Arizona Geological Survey Digital Information Series DI-18.2.2.
7. Map image produced by selection and symbolization of features from an existing digital geologic data set or database. Authorship of map image is different from authorship of digital data. Authorship role is 'compiler'. File format information for the underlying digital data set may be omitted for brevity.
Richard, S.M., compiler, 2000, Geologic map of Tertiary rocks in the Clifton-Morenci area, Greenlee County, Arizona: Tucson, Arizona Geological Survey Open-File Report 00-000, 1 sheet, scale 1:50,000. Derived from Ferguson, C.A., Enders, M.S., and Orr, T.R., 2000, Geologic spatial data for the Clifton-Morenci area, Greenlee County, Arizona: Tucson, Arizona Geological Survey Digital Information Series DI-18, 5 ArcInfo export (e00) files, 36 ESRI shape (shp) files, and other files.

Pearthree, P.A., compiler, 2005, Quaternary geology of Yavapai County: Arizona, Tucson, Arizona Geological Survey Open-File Report 05-0053, 1 sheet, scale 1:500,000. Derived from Arizona Geological Survey, 2005, Geologic Spatial Data for Arizona (ver. 6.2): Tucson, Arizona Geological Survey Digital Information Series DI-99.6.2.

Orr, T.R., compiler, 2002, Map showing approximate potassium content of bedrock formations in the Grasshopper Junction area, Mohave County, Arizona: Tucson, Arizona Geological Survey Open-File Report 02-32, 1 sheet, scale 1:50000. Derived from Gray, F. P, 2002, Geologic spatial data for the Needles 1 by 2-degree quadrangle (ver. 2): Tucson, Arizona Geological Survey Digital Information Series DI-41.2, 5 MapInfo (mif/mid) files, 1 Adobe Acrobat (pdf) file.

8. Map image is generated by a geoscience database query and automated cartographic procedures. The map image reflects the current state of the database. Cartographic design is founded in the design of the map query and automated cartographic procedures. The map extent and choice of features to symbolize may be unique to this particular map. Intellectual authorship for the geologic data set is based on sources of individual geologic features selected to symbolize by the query. Authorship of view is institutional. The map image must include citations for sources of all geologic data represented on map, and an index map showing the extent of data sources. Reference to database must include time stamp or version identification. File format information for the underlying digital data set may be omitted for brevity. If the source database is updated continuously, the institution maintaining the database must time stamp individual features and archive superseded features to document evolution of the database.
Arizona Geological Survey, 2009, Digital geologic map of the proposed White Tank National Monument, Maricopa County, Arizona [View]: Tucson, Arizona Geological Survey Map on Demand MOD-77, 1 Adobe Acrobat file, map layout scale 1:50,000. Derived from Arizona Geological Survey, 2009, Geologic Spatial Database for Arizona (ver. 10.6): Tucson, Arizona Geological Survey Digital Information Series DI-99.10.6.
9. Map image represents modification of part of a published map image without the collaboration of the original authors or review of the entire data set. The modifications involve changes to the underlying geologic data set. The modified map represents the same geographic extent, and the cartographic design remains the same. This situation will arise for geological surveys that wish to include reliable, up-to-date information on maps they provide to users. New data may supersede parts of a geologic data set represented on a published map image, and it is desirable to update the map image with the new data. The authorship of the new data is different from the authorship of the original data set, and the authorship of the original data set is not involved in the update. The map image becomes a geologic data anthology as opposed to a compilation, because there is no single authorship for the entire data set represented by the image. The word "[anthology]" should be appended to the title. If the total number of authors involved is small (6?) include all authors in the citation, and specify the author role to be 'contributors'. Order of authorship should reflect the relative contribution to the map. If this is indeterminate, authors should be listed in alphabetical order. If the number of authors becomes large, or questions of order of authorship cannot be resolved, the map should be cited with institutional authorship. The map must include an index map showing the extent of updates and documenting the authorship and date of all updates. Update history must be documented by establishing version identification or a time-stamp that becomes part of the citation. The publishing agency must maintain archival materials documenting all updates to the map. The following examples show progressive development of an anthology.
Richard, S.M., compiler, 2000, Digital geologic map of the Globe 30' X 60' quadrangle: Tucson, Arizona Geological Survey Digital Information Series DI-33, 2 Adobe Acrobat (pdf) Files, map layout scale 1:100,000.

Richard, S.M., and Spencer, J.E., compilers, 2001, Digital geologic map of the Globe 30' X 60' quadrangle (ver. 2): Tucson, Arizona Geological Survey Digital Information Series DI-33.2, 2 Adobe Acrobat (pdf) Files, map layout scale 1:100,000.

Richard, S.M., Wrucke, C.A., and Spencer, J.E., contributors, 2003, Digital geologic map of the Globe 30' X 60' quadrangle [Anthology] (ver. 3): Tucson, Arizona Geological Survey Digital Information Series DI-33.3, 2 Adobe Acrobat (pdf) Files, map layout scale 1:100,000.

Random, P.P., Random, X.Y., Richard, S.M., Spencer, J.E., and Wrucke, C.A., contributors, 2008, Digital geologic map of the Globe 30' X 60' quadrangle [Anthology] (ver. 4): Tucson, Arizona Geological Survey Digital Information Series DI-33.4, 1 Brownmud Universal (uuu) File, map layout scale 1:100,000.

Arizona Geological Survey, 2010, Digital geologic map of the Globe 30' X 60' quadrangle [Anthology] (ver. 5): Tucson, Arizona Geological Survey Digital Information Series DI-33.5, 1 Solar WorldDomination (swd) File, map layout scale 1:100,000.

DIGITAL GEOLOGIC DATA EXAMPLES

The following are example citations for various sorts of digital geologic data. As in the previous section, example citations to Virginia maps are based on examples in Berquist (1999), and are included to show how they fit into the scheme proposed here. A citation for any digital geologic data set should clearly define the source of the underlying geologic data set, the publisher of the data set, and the number and format of the file(s) that contain the data set and any associated text. The physical media (floppy disks, CDROM, DVD....) that contain the files is not essential to an intellectual citation, since the files can be copied between media, or may be transferred directly across a network. For library cataloging purposes, the physical media would need to be noted as well.

10. Digital geologic data set derived from a single published source. In these examples, Richard and Thieme, and Smith were responsible for the conversion of the published map image to a digital geologic data set. Citation of the geologic spatial data is appropriate when something particular to that specific digital data set is being cited. If the underlying geologic data set is being cited, the citation should be to the original published map image.

Richard, S.M., and Thieme, J.P., compilers, 2000, Geologic Spatial Data for the Phoenix North 30' x 60' Quadrangle: Tucson, Arizona Geological Survey Digital Information Series DI-4 (ver. 2), 3 ArcInfo Export (e00) files, 3 ESRI Shape (shp) files, 1 Adobe Acrobat (pdf) file. Adapted from Reynolds, S.J., and Grubensky, M.J., 1993, Geological Map of the Phoenix North, Central Arizona: Tucson, Arizona Geological Survey Open-File Report 93-17, 1 sheet, scale 1:100,000.

Smith, Jane, compiler, 1998, Geologic spatial data for the Walkers quadrangle, Virginia: Richmond, Virginia Division of Mineral Resources Digital Publication DP-6, 4 AutoDesk Autocad Interchange (dxf) files, 1 Microsoft Word (doc) file, 3 dBase database (dbf) files. Adapted from Doe, John, 1997, Geologic map of the Walker Quadrangle, Virginia [scan]: Richmond, Virginia Division of Mineral Resources Manuscript Map 97-3, 1 tagged image format (tif) file, map layout scale 1:24,000.

11. Digital geologic data set derived from field data collected under a single authorship, or from an unpublished manuscript map compiled under a single authorship (no citable version of map image exists). If the data set is updateable, the citation must include version identification or a time stamp to document the database state cited. The date in the citation is the release date for the data actually cited. In this example, geologic mapping was by Ferguson and Enders, and the field data were digitized and edited by Ferguson and Orr. The data set is not versioned or time-stamped, implying that there is only one extant version of the data set.
Ferguson, C.A., Enders, M.S., and Orr, T.R., 2000, Geologic spatial data for the Clifton-Morenci area; Coronado Mountain, Mitchell Peak, Copperplate Gulch, and Clifton 7.5' quadrangles, Greenlee County, Arizona: Tucson, Arizona Geological Survey Digital Information Series DI-18, 5 ArcInfo export (e00) files, 36 ESRI shape (shp) files, and other files.
12. A compiled geologic spatial data set that includes data from a variety of authors, and is independent of any particular map image. Citation of authorship with a compiler role denotes that the authorship has reviewed data from source data sets for consistency and reconciled any discrepancies, and has edited the complete data set for accuracy. If the data set is versioned, version identification must be included in the citation, along with the version release date. Authorship may change between versions, but citation of authorship as compilers always denotes that the entire dataset has been reviewed and edited as necessary. Determination if a compilation is a new version of an existing compilation or a new work must be decided based on institutional guidelines or agreement by the authors. The spatial extent must be identical in order to qualify as an update of an existing compilation. If a data set is updated periodically and updates are not too numerous, revision dates should be listed (revised 2000, July 5; 2001, March 15; 2001, Sept. 27). If this becomes untenable, the citation must include a date that exactly defines the cited data set (e.g. dated 2000, July 5, 3 p.m.). A continuously updated data set must include information on the origin and update history of all updateable features. The version identifier or release date for the data set cited is indicated in parenthesis after the data set title. The year listed in the citation is for the release date of the data actually cited.

In this example citation for a versioned database, Richard and Orr compiled, reviewed, digitized and edited the data. Version 2.1 was released in 2002.

Richard, S.M., and Orr, T.M., compilers, 2002, Geologic spatial data for the Globe 30 by 60 minute quadrangle, Arizona (ver. 2.1): Tucson, Arizona Geological Survey Digital Information Series DI-22.2.1, 6 ArcInfo export (e00) files, 1 Microsoft Access Database (mdb) file.
In this example citation for a continuously updated database, Berquist, Uschner, and Ambroziak compiled, reviewed, digitized and edited the data. The cited data were released July 5, 2000. The time stamp is included in parenthesis after the series title and number.
Berquist, C.R., Jr., Uschner, N.E., and Ambroziak, R.A., compilers, 2000, Geologic spatial data for the State of Virginia (dated 2000, July 5): Richmond, Virginia Division of Mineral Resources Digital Publication DP-14-B, 15 ArcInfo export (e00) files, 1 Microsoft Access Database (mdb) file, 1 Adobe Acrobat (pdf) file.
13. Geologic spatial data derived by conversion of a published data set to a different logical schema or implementation environment. The data conversion is designed to preserve the information content of the original dataset, but some information may be lost or corrupted. Conversion is beyond the control of the original database compiler(s). Intellectual authorship of geologic data set remains the same, and should retain primacy in the citation. Data conversion information is indicated by an 'adapted by..' (in italics) clause after the publisher and series identifier for the original data. The data conversion authorship, the date of conversion, publisher of the data in the new format, and file format for the new version must be included.
Richard, S.M., and Orr, T.M., compilers, 2002, Geologic spatial data for the Globe 30 by 60 minute quadrangle, Arizona (ver. 2.1): Tucson, Arizona Geological Survey Digital Information Series DI-22.2.1, adapted by Stanley, M.S., 2003, Tucson, Arizona, RSI Inc., 6 Map/Info (mif) files, 1 Lotus Approach Database (lad) file.
14. A variety of data sets are combined in a single data structure by authors operating independently. This may be the case for a single or compiled data set updated by an authorship different from the original authorship, or for a database consisting of data sets from multiple sources that have not been compiled. The result is a data anthology or database. There is no single authorship for the entire data set. Authorship citation follows the conventions suggested in case 9 above. The word "[anthology]" should be appended to the title. If the total number of authors involved is small (6?) include all authors in the citation, and specify the author role to be 'contributors'. Order of authorship should reflect the relative contribution to the map. If this is indeterminate, authors should be listed in alphabetical order. If the number of authors becomes large, or questions of order of authorship cannot be resolved, the database should be cited with institutional authorship. Such a database must maintain tracking records to document the origin of the geologic data contained therein. The tracking record must include citation information for all original sources of data. If the database is updated in a succession of versions, archival copies of superceded versions must be maintained. If the database is updated continuously, individual features must be time stamped to document the period during which they are considered current. Obsolete features must be archived, and may be removed from the current copy of the database after they are archived. Use of the term "database" in the title of a work implies that the work represents a data anthology; if the term database is not included in the title, then "[Anthology]" should appear somewhere in the title.
Richard, S.M., Spencer, J.E., Wrucke, C.M., and Orr, T.M., contributors, 2004, Geologic spatial data for the Globe 30 by 60 minute quadrangle, Arizona [anthology] (ver. 4.1): Tucson, Arizona Geological Survey Digital Information Series DI-22.4.1, 6 ArcInfo export (e00) files, 1 Microsoft Access Database (mdb) file.

Arizona Geological Survey, 2009, Geologic spatial database for Arizona (ver. 10.6): Tucson, Arizona Geological Survey Digital Information Series DI-99.10.6, 1 ESRI Geodatabase, 1 Microsoft Access database (mdb) file, 1 Adobe Acrobat (pdf) file.

Arizona Dept. Water Resources, 2005, Geologic spatial data for the Tucson Basin [anthology] (ver. 0.5): Phoenix, Arizona Dept. Water Resources Open-File Database 22, 1 Manifold database (mfd) file, 1 Microsoft Access database (mdb) file, 1 Adobe Acrobat (pdf) file.

NOTE:
It is important to inform users of the conventions used for authorship and citation (Berquist, 1999). To insure consistent citation of the data, include statements similar to the following text on any published map image, printed on the physical media used to deliver digital data, and in a 'Readme' file included with any data or map image that is transferred electronically:

Digital Publication 7 - Appalachia Quadrangle

Digital Publication DP-7-A is a digital geologic map image. The bibliographic citation for geologic content of this image is as follows:
Nolde, J.E., Henderson, Jr., and Miller, R.L., 1988, Geology of the Virginia portion of the Appalachia and Benham quadrangles: Richmond, Virginia Division of Mineral Resources Publication 72, 1 sheet, scale 1:125,000.

Bibliographic citation specifically to this digital file:
Virginia Division of Mineral Resources, 1998, Digital representation of geologic map of the Virginia portion of the Appalachia quadrangle: Richmond, Virginia Division of Mineral Resources Digital Publication DP-7-A, 1 encapsulated postscript (eps) file, map layout scale 1:125,000. Adapted from Nolde, J.E., Henderson, Jr., and Miller, R.L., 1988, Geology of the Virginia portion of the Appalachia and Benham quadrangles: Richmond, Virginia Division of Mineral Resources Publication 72, 1 sheet, scale 1:125,000.

Digital Publication DP-7-B is a digital data set. Geologic information, concepts, and other products gained from the use of these files should be credited as follows:
Uschner, N.E., Jones, K.B., Sheres, D.E., and Giorgis, S.D., 1998, Geologic spatial data for the Virginia portion of the Appalachia quadrangle: Richmond, Virginia Division of Mineral Resources Digital Publication DP-7-B, 7 ESRI shape (shp) files. Adapted from Nolde, J.E., Henderson, Jr., and Miller, R.L., 1988, Geology of the Virginia portion of the Appalachia and Benham quadrangles: Virginia Division of Mineral Resources Publication 72, 1 sheet, scale 1:125,000.

TERMINOLOGY:

Adapted from--indicates derivation of digital data from a published map image.

Adapted by--indicates derivation of digital data by conversion from a different implementation or logical data structure.

Anthology--indicates aggregation of information without complete review and editing under a single authorship.

Authorship--the collection of persons responsible for the content of a document. Shared authorship and the order of authors would follow normal standards of mutual agreement between those involved with creation of the particular work. This includes consideration of the level of effort of digital compilers and digital editors for authorship of the digital files. Deceased geologic authors will gain a posthumous publication for their geologic map (image) if this convention is adopted.

Based on--indicates production of a map image by minor revision of another map image.

Cartographic design--the process of choosing the graphical elements to represent geographic features and related information on a map image, and arranging the elements for maximum legibility and clarity.

Citation--The formal identification of a document. A citation must specify the authorship, title, date of publication, particular version of a document if it is subject to update, publisher, publisher's identification for work, and medium that contains the work. If a document is derived from another document, the citation should specify the relationship to the other document and cite the original document.

Compilation--integration of data from several sources, including review for consistency and resolution of inconsistencies.

Contributor--a role specifier that indicates independent authorship of different parts of a geologic data set.

Data conversion--process of converting data representation from lines and symbols on a physical map image to digital file(s).

Data editing--reviewing compiled or converted data for accuracy, and correcting errors in topology, location, or classification to be consistent with the original source.

Derived from--indicates that a map image was produced directly from a digital geologic data set.

Digital map image--a map image in a digital-encoded form that requires the use of machinery to render in a form that is useful to humans.

Digital publication--a citable electronic document that has an immutable identity.

Display--rendering of a map image to a visible form, either on a screen or on paper.

Document--the original, official, or legal form of something, which can be used to furnish decisive evidence or information. This is generalized from The American Heritage Dictionary (Second College Edition, 1982) by removing the restriction that the representation be contained on paper.

Geologic data set--collection of map unit definitions, interpretations of the nature of the boundaries between the map units, locations of faults and boundaries between the map units defined, and descriptions (quantitative and qualitative) of the internal structure of the map units.

Institutional authorship--Applied to geologic data sets that evolve over time as updates are made, and to map images that represent such data sets. Updates are not reviewed and approved by a single authorship. Authority for maintenance of the data set resides with a particular institution, and is based on the standards for accuracy and reliability of the institution. Document so cited has rank of an anthology.

Map image--a particular visualization of the interpretation of geologic data for an area, defined by the bounding polygon for the map area, the map projection, the elevation model for the surface represented, the geologic data used, the choice of symbols for geologic features, and the cultural and physiographic base map.

Physical Map image--map image on physical media (typically paper or film) in a form directly useful to humans.

Published database--a particular collection of data arranged in a fixed data structure. The data structure must be described in text accompanying the database or in a separate document. If the database is subject to updates, a mechanism must be defined whereby a citation to the database identifies the exact cited database state.

Publication--A document that is identified by a citation, and made available through some public venue.

REFERENCES

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, https://pubs.usgs.gov/openfile/of99-386/berquist.html.

U.S. Geological Survey, 1995, Draft cartographic and digital standard for geologic map information: U.S. Geological Survey Open-File Report 95-525, pagination varies.

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U.S.Department of the Interior, U.S. Geological Survey
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Last updated 11.01.00