USGS

Digital Mapping Techniques '99 -- Workshop Proceedings
U.S. Geological Survey Open-File Report 99-386

Geologic Mapping at the Oklahoma Geological Survey: The Move From Traditional to Digital Cartography

By T. Wayne Furr

Oklahoma Geological Survey
Norman, Oklahoma 73019-0628
Telephone: (405) 325-3031
Fax: (405) 325-7069
e-mail: twfurr@ou.edu

The Oklahoma Geological Survey (OGS) has maintained a strong commitment to mapping the geology and natural resources of the State of Oklahoma; a commitment that began before statehood with its predecessor organization, the Oklahoma Territorial Geological Survey. In 1904, before becoming the first State Geologist, Dr. Charles N. Gould, prepared a preliminary geologic map of the Oklahoma Territory. Three years later, Gould contributed to the development of the enabling act for the creation of the state geological survey. When comparing length of service to other state geological surveys OGS may be considered an infant. However, OGS claims the distinction of being the only state geological survey in the nation to have been created under a directive of the constitution of a newly formed state.

The objectives and duties of the new survey were defined by Oklahoma's First Legislature. Senate Bill No. 75 provided for a study of the geological formations of the State with special reference to its mineral deposits, including the preparation and publication of reports with maps. The reports are to provide both general and detailed descriptions of the State's geological resources.

The first full-color geologic map of Oklahoma, compiled by Hugh D. Miser of the U.S. Geological Survey (USGS), was released in 1926. After 20 years of use, the map not only was outdated it was out of print as well. In 1947, Miser returned to Norman to supervise revision of the 1926 map. Miser and 10 additional authors are given credit for the geologic map of Oklahoma that was released in 1954 (Ham, 1983, p. 7). Forty-five years later the map is still in use, but in need of major revisions. Mapping and other kinds of field studies have continued with the completion of 145 Bulletins, 100 Circulars, 35 Mineral Reports, 31 Guidebooks, 5 Educational Publications, 35 Geologic Maps, 9 Hydrologic Atlases, 65 Special Publications, and 45 Open-File Reports.

MAPPING PROGRAMS

Currently, OGS is conducting four kinds of geological mapping programs: county, resource, 7.5-minute quadrangle, and 1:100,000 digital compilation. The purpose of these programs is to provide a better understanding of the State's geological history and resources. The knowledge gained will enable public policy-makers and industry to safely and wisely utilize Oklahoma's geological resources.

For more than 70 years, county mapping has been the cornerstone of geological investigations at OGS. Kay County, located in north-central Oklahoma is the most recent to be mapped. Currently, geologic investigations are underway in the western part of Osage County. Traditionally, investigations in the county geological mapping program have been produced in the Bulletin and Circular Series with maps at a scale of 1:63,360.

Recent resource mapping in Oklahoma has focused on the coal reserves and environmental problems associated with past mining, including poor reclamation techniques. The principal user of the OGS coal-resource maps is industry. Several mines in the State have been developed based on information provided from these studies.

Beginning in 1985, a program to map the northern part of the Ouachita Mountains fold-and-thrust belt and the southern part of the Arkoma foreland basin was conducted. Designed to support natural-gas exploration and coal development, and to reduce associated environmental hazards, 22 geological-quadrangle maps were produced. In 1998, OGS shifted new mapping efforts to the northern Oklahoma City metropolitan area. Twelve 7.5-minute quadrangles were selected, with completion expected by July of the year 2000. The purpose of this mapping is to provide area planners with detailed geologic maps that will enable them to make informed decisions with regard to aquifer protection, resource development, and highway construction.

In late 1994, the Oklahoma Geologic Mapping Advisory Committee (OGMAC) recommended that OGS prepare a series of geologic maps at a scale of 1:100,000 for the entire State using digital technology. The purpose of the maps is to provide a Geographical Information System (GIS) geologic data base for industry, public officials, area planners, and other interested parties. In addition, this series will provide the foundation for a new 1:500,000-scale geologic map of the State. Maps in this series are compilations of geologic investigations from various sources, with field checks used to fill gaps found in prior investigations and improve on earlier mapping efforts.

Partial funding for the OGS geological mapping activities has been provided under two separate grants. From 1985 to 1993, mapping was funded through the COGEOMAP Program, an agreement between the OGS, the Arkansas Geological Commission, and the USGS. Since 1994, geologic mapping has been funded through the STATEMAP component of the National Cooperative Geologic Mapping Program.

1:100,000-SCALE DIGITAL COMPILATION

In 19961997, two 30 x 60 minute quadrangles in western Oklahoma were compiled to test OGS compilation efforts and digital capabilities. The Watonga and Foss Reservoir quadrangles (figure 1) were chosen because the bedrock geology, consisting mostly of gently dipping Permian redbeds, is relatively simple and well known. The highly dissected terrain, however, results in complex cartographic patterns.

In September 1996, OGMAC recommended that OGS concentrate on the Oklahoma Panhandle. The mapping will complement ongoing studies in the area conducted by the Oklahoma Water Resources Board and Water Resources Division of the USGS. Investigations by each agency will provide a better understanding of environmental issues associated with an increasing transportation infrastructure, numbers of feed lots, and meat-processing plants. OGS geologists started compiling the geology in the westernmost quadrangle in 1997. The digitizing, GIS-attributing, and cartographic production has essentially been completed on the Boise City Quadrangle. Completion of the Guymon and Beaver quadrangles is expected by the end of June 1999 (figure 1).

Figure 1

Figure 1. Index to 1:100,000-scale geologic maps in Oklahoma.

Methods Used

I. OGS Geologist
1. Conducts library research and compiles all existing modern geologic contacts on a 1:100,000 green-line base (Note: A green-line base is a frosted-film sheet with the base map printed in green).

2. Supplements compilation and resolves different geologic maps with air-photo interpretation and/or reconnaissance field checking.

3. After compilation, a paper print is made and the geologist colors the formations, checking for gaps or open formation contacts.

4. An explanation, area of investigation map, and other necessary information is prepared.

5. This package of information is turned over to the cartographer for processing.

II. OGS Cartographic Staff

6. Using scribing, the cartographer makes a line-work separation of the geologic contacts from the base map.

7. Prepares a geologic color-selection guide

8. Prepares a map layout guide.

9. Makes a clear film or paper photo print of the geologic line work.

10. The photo print, color selection guide, and map layout guide is turned over to the GIS specialist. Currently, the GIS processing is under contract to an individual at Oklahoma State University (OSU).

III. GIS Specialist

11. The specialist scans the 1:100,000-scale photo positive of the geologic map sheet at 400 dots per inch on an ANAtec 3640 Eagle optical scanner.

12. The scanned (raster) image is converted to vector polygons utilizing LtPlus raster-to-vector conversion software on a SUN SPARC workstation.

13. A plot of the digital vector data is made at 1:100,000 scale on an HP650C plotter and visually compared with the original map compilation to ensure completeness and precision of scanning and data conversion.

14. Within LtPlus, polygon topology is created, each polygon is attributed, and a series of quality-control checks is performed with software macros (programs).

15. The digital data is then exported from LtPlus in standard USGS DLG-3 format and imported into Arc/Info version 7.0.3.

16. A plotting routine is written and executed in Arc Macro Language program to utilize the digital geology polygons as part of a 1:100,000-scale geologic map.

17. Base map layers, a title, explanation, text, and index maps are added to complete the map layout.

18. On request, the completed map data sets will be made available to the public in one of the following formats: (a) Arc/Info export format (.e00), (b) ArcView shapefiles, or (c) USGS DLG-3 format for access through the World Wide Web via a Web browser or by file transfer protocol (ftp) (Furr, Gregory, and Suneson, 1998). Note: At the present time, the exact procedure, file format, and method of distribution described in step 18 have not been determined.

GIS vs. Published Maps

In addition to the GIS format, Dr. Charles J. Mankin, Director of OGS, expressed the need to publish each geologic quadrangle in full color for release in our Geologic Map Series. Having two different types of digital products presented a different set of problems. The biggest complaint expressed by reviewers of printed GIS maps was graphic presentation. They expected to see standard geologic colors, lettering, and other symbols. Unfortunately, graphic presentation has never been a strong point in most GIS programs. Another problem was converting the GIS files to a publishable format. A GIS is an analysis tool designed to evaluate a range of possible scenarios. By evaluating different possibilities, a course of action can be considered before irrevocable mistakes are made in the landscape itself (Burrough, 1986, p. 7). In other words, a GIS was never intended to be the computer toolbox for designing, drafting, and printing maps in the traditional way. As a result, from the GIS file format, it is difficult to provide to the printing industry a digital file that is compatible with the industry's graphic-output devices.

These problems and others have been addressed by agencies that have tried to use a GIS as a publishing tool. In checking with other state geological surveys, private cartographic firms, pre-press, and printing companies, the answers are not entirely clear. Many agencies use Macintosh computers, others use PCs with a variety of operating systems, and others use UNIX-based workstations. A multitude of software was also found to be in use. Some were using one of several GIS programs, some were using CAD programs, while others were using a variety of graphic software programs. The pre-press and printing firms were not familiar with GIS file formats, but preferred to use files created in Adobe Illustrator.

The OGS Cartographic Section's computer setup consists of Pentium II PCs with Windows NT operating systems. Software includes Microsoft Office, ArcView 3.0a, and Adobe Illustrator 7.0.1. One problem that had to be addressed was how to import GIS files to Illustrator while maintaining the GIS attributing. For this operation, third-party software was needed to bridge the gap between ArcView shapefiles and Adobe Illustrator. The third-party software chosen was MAPublisher from Avenza Software. MAPublisher is a cartographic-geographic information system for integrating GIS files directly into Adobe Illustrator while maintaining the GIS attributing. The plug-in filters allow the cartographer to consider map projections, scale, color, and necessary cartographic operations, while maintaining the GIS functionality. The completed map project can be saved in one of the many formats used by the pre-press and printing industry. In addition, map layers can be exported as shapefiles for use in a GIS.

Adjustments to OGS Methods

As a result of the lessons learned from the Watonga and Foss Reservoir quadrangles and the availability of new software, several changes in the method of map production were made as work progressed on the Boise City quadrangle. Steps 1 through 16 described previously remained the same. One change being considered for future projects is dropping the printed green-line base in favor of a clear-film base map with a frosted-mylar overlay. The expected goal is that the geologist carefully drafting the geologic contacts will eliminate the need for the cartographer to make a line-work separation and the expense of a photographic positive.

Adjusted Methods

To recap step 16 from before: A plotting routine is written and executed in Arc Macro Language program to utilize the digital geology polygons as part of a 1:100,000-scale geologic map.

17. The geologic-polygon and base map image file layers are placed on the OSU (Department of Plant and Soil Sciences) file server in ArcView shapefile format.

18. The cartographer transfers the files to the OGS computer network using standard file transfer protocol (ftp)

19. The ArcView shapefiles are moved into Adobe Illustrator using MAPublisher's import filter.

20. Using Illustrator, the cartographer performs the necessary cartographic work to bring the map to OGS standards by adding the title, explanation, index map(s), geologic letter symbols, and colors.

21. File formats for printing the maps are created and sent to the printer.

22. The geologic map data base is exported in ArcView shapefile format for use in GIS applications.

23. On request, the completed map data sets will be made available to the public in one of the following formats: (a) Arc/Info export format (.e00), (b) ArcView shapefiles, or (c) USGS DLG-3 format for access through the World Wide Web via a Web browser or by file transfer protocol (ftp). Note: At the present time, the exact procedure, file format, and method of distribution described in step 23 have not been determined.

SUMMARY

The OGS Cartographic Section started using computers to produce figures and illustrations for publications about five years ago. Geologic maps in the 1:100,000-scale series are the Survey's first attempt at using GIS concepts and graphics software jointly to produce maps for printing. The methods used provide a workable solution that can be adopted by agencies with similar production needs. Cartographic production of the Boise City map was approximately three times faster than traditional drafting methods. The need for cartographic materials, such as scribe-sheets, peel-coats, type-overlays, and other traditional materials, as well as the use of supporting laboratories is virtually eliminated. The various geological mapping programs at OGS are expected to expand as experience is gained using GIS in combination with digital cartography. To accomplish overall goals, methods will be adjusted and production speed is expected to increase. With materials and support for traditional cartographic methods diminishing the need to totally convert to digital production for all maps at the OGS is rapidly approaching.

Future mapping will include additional 7.5-minute quadrangles in the Oklahoma City area and 1:100,000-scale quadrangle(s) in western Oklahoma. Additional projects being considered for production in both digital and publishable formats are the Oil and Gas Map of Oklahoma at a scale of 1:500,000, the Geologic Province Map of Oklahoma at a scale of 1:750,000, and the expanded revision of Educational Publication 1. In addition to the geologic mapping programs, an inventory of all geologic maps published by OGS is being compiled and entered into the National Geologic Map Database <http://ngmdb.usgs.gov>. As a state agency, the Oklahoma Geological Survey has made a commitment to meet the needs of the State's citizens by providing high-quality printed maps, as well as GIS data bases of the State's geological resources.

REFERENCES

Burrough, P.A., 1986 (10th printing with corrections, 1993), Principles of Geographical Information Systems for Land Resources Assessment: Oxford University Press, Inc., New York, 194 p.

Furr, T.W., Gregory, M.S., and Suneson, N.H., 1998, Oklahoma Geological Survey's (OGS) digital geologic maps (abs.): Geological Society of America Abstracts with Programs, v. 30, no. 3, p. 6.

Ham, E.A., 1983, A History of the Oklahoma Geological Survey 19081983: Oklahoma Geological Survey Special Publication 83-2, 60 p.


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