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


Twenty agencies exhibited posters throughout the workshop. These posters provided an excellent focus for technical discussions and support for oral presentations. Depending on the nature of their poster, the authors provided summaries ranging from a brief description to a more formal paper of some length. The brief descriptions are given below, alphabetically by state. In some cases, the poster directly supported an oral presentation in this volume, and no mention is provided here. These brief descriptions are followed by the more lengthy contributions, by Ross (Kansas Geological Survey), Gregson (National Park Service), McCraw and others (New Mexico Bureau of Mines and Mineral Resources), Tremblay and others (Texas Bureau of Economic Geology), and Haugerud and Greenberg (U.S. Geological Survey and University of Washington).

Map Production at the Alaska Division of Geological and Geophysical Surveys Expands with Growing Digital Geologic Database

By Gail Davidson, Gina R.C. Graham, L. Katherine Queen, Alfred G. Sturmann, DeAnne S. Pinney, and Andrew M. McCarthy

Alaska Division of Geological and Geophysical Surveys
794 University Avenue, Suite 200
Fairbanks, AK 99709
Telephone: (907) 451-5006
Fax: (907) 451-5050

During the past 15 years, the technology of map production at the Alaska Division of Geological and Geophysical Surveys has evolved from hand-scribed peel coats to digital maps and images generated in Arc/Info. As technology changes, the production methods for geologic maps are continually being refined and updated to take advantage of the capabilities of new technologies. Geologic maps currently produced by DGGS are created electronically from a growing digital database. Formerly maps were released as bluelines from inked drawings or as offset-printed Professional Reports. With the rising costs of printing and storage, maps are now produced on demand directly from an electrostatic plotter or in PDF format on the World Wide Web. Continued growth of the geologic database has allowed more efficient production of "classical" geologic maps as well as expanded use of the data for derivative maps. Advances in digital technologies not only allow us to produce "smart maps" but also allow us to better emulate the look and feel of classic cartographic products.

Two project examples are shown. A map series of the Kandik River Basin area in Alaska was produced by combining digitized geologic data with geophysical data gathered using relatively new technologies. A geologic map of the eastern half of the McGrath quadrangle is a compilation of DGGS field work completed over many years and contains both published and unpublished data. Future plans include a meshing of geological and geophysical data to pinpoint areas with high mineral potential to aid in the ongoing search for economically feasible mineral extraction.

Geologic Mapping for Hazards Evaluation and Zonation on the Whittier 7.5' Quadrangle, Los Angeles County, California

By George J. Saucedo and David L. Wagner

California Division of Mines and Geology 801 K Street, MS 12-31
Sacramento, CA 95814
Telephone: (916) 324-7380
Fax: (916) 322-4765

Most of the early areal geologic mapping conducted in the Los Angeles Basin provided the data for interpreting the stratigraphy and complex structure necessary in the search for petroleum. Emphasis of the early mapping was directed toward the uplands where Tertiary marine strata are exposed. Though bedrock types and structure are components for analysis of hazards, data on Quaternary deposits and landslide inventories are also required. Since most hazard analysis is now done on geographic information systems (GIS), the data should be in digital form. The Whittier 7.5' quadrangle was the first map compiled by the California Division of Mines and Geology's (DMG) Regional Geologic Mapping Project specifically for hazards analysis and eventual zonation by the Seismic Hazards Zonation Program. The mapping and compilation of the Whittier quadrangle were supported in part by the U.S. Geological Survey (USGS) through STATEMAP and are part of the Southern California Areal Mapping Project, a cooperative effort between the DMG and the USGS.

Existing geologic mapping was compiled in the Puente Hills, covering about ten percent of the quadrangle. New mapping of the Quaternary deposits covers the rest of the map. The Quaternary units were mapped on the basis of grain size, age, and origin, according to a classification scheme developed for the Southern California Areal Mapping Project. The map is a 1:24,000 scale digital database in Arc/Info.

Idaho Geological Survey Cartographic Update

By Loudon R. Stanford and Jane S. Freed

Idaho Geological Survey
Morrill Hall, Third Floor
University of Idaho
Moscow, ID 83843-3014
Telephone: (208) 885-7479
Fax: (208) 885-5826

The displayed maps show how the Idaho Geological Survey has successfully met its goal of producing full-color, plot-on-demand geologic maps as outlined in our paper presented at the 1997 workshop. The CAD-finished geology is imported into the publication layout program FreeHand where the DRG base map and legend material are laid out. Once complete, the map is sent to the color plotter (2500 HP) as a PostScript file.

AutoCAD with CADMappr continues to be the software of choice for data capture. Geology is digitized by hand on high-accuracy digitizing tablets or by high-resolution scanner with subsequent data conversion and extraction. Ultimately the data sets are exported to Arc/Info where coverages are built. Full metadata come with all released data sets and are easily accessible through links in ArcView.

We would be happy to answer any questions you may have.

Well Data as a Framework for the Third Dimension in a Digital Geologic Map Database

By David R. Collins

Kansas Geological Survey
1930 Constant Avenue
Campus West, University of Kansas
Lawrence, KS 66047
Telephone: (913) 864-3965
Fax: (913) 864-5317

The history of digital geologic map database development has focused on the capture, management, and visualization of data representing surface or near surface outcrop patterns of local geologic formations. This presentation will focus on efforts to characterize and visualize the regional subsurface stratigraphic framework associated with the surface expression of outcrop patterns. Even when data from only a single well is available within a map area, the visualization techniques presented here are potentially beneficial as a means for making the data and its interpretation more accessible to potential users. The techniques can be used most effectively in regions with extensive exploration drilling in the subsurface, such as mature petroleum plays.

Many states and provinces in North America have extensive collections of well logs in analog form and in some areas digital well log databases have been developed. Increased availability of digital well log data in Kansas has been a positive result of several major research efforts at the Kansas Geological Survey (KGS). Standardization of digital log formats using the Canadian Log ASCII Standards (LAS), and the addition of geographic coordinate locations to well log header record information has simplified technical problems related to display and visualization of well log data within a regional context. Access to this data by the general scientific community is now possible through the KGS home page ( on the Internet. A study of the Dakota Formation has provided digital data from gamma ray logs of more than 1500 wells throughout western Kansas. The data from this project covers stratigraphic units from the Quaternary and Cretaceous systems through the Nippewalla Group of the Lower Permian. Log data has been developed in conjunction with the KGS Petroleum Atlas and other KGS database development efforts. More logs will be placed in the on-line databases as they become available. Examples are provided of regional cross sections and single well displays generated from these databases using COLORLITH, a program for log data visualization developed by the author at the KGS.

Coastal Erosion, Chesapeake Bay, Maryland: A Digital Approach

By Lamere Hennessee,1 Randall T. Kerhin,1 Jennifer J. Isoldi,1 Rebecca A. Gast,1 and Meredith S. Robertson2

1Maryland Geological Survey
2300 St. Paul Street
Baltimore, MD 21218
Telephone: (410) 554-5519

2Dickinson College
Carlisle, PA

Chesapeake Bay is one of Maryland's most significant physical features. Within the state, the total shoreline of the bay and its tidal tributaries is about 6,400 km. Along most of its length, the shoreline is eroding. To quantify shoreline change, the Maryland Geological Survey (MGS) (1) converted the shorelines depicted on historical recent maps and aerial photographs to digital (vector) format and (2) applied a computer program developed by the U.S. Geological Survey to calculate linear rates of erosion along shore-perpendicular transects. These statistics, combined with bank height and stratigraphic information, are used to compute the volume and type of sediment lost. In phase 3, the graphic information (shoreline vectors and shore-perpendicular transects) and tabular information (shore erosion statistics) are linked in a user-friendly, point-and click electronic atlas‹MGS's Coastal Geology Information System (CGIS). Other data sets or layers, such as the physical properties of beach and nearshore sediments, are also included in the atlas. The CGIS can be used to address a variety of coastal issues, for example, (1) determining set-backs for flood insurance or other purposes, particularly in areas at high risk of erosion, (2) calculating a sediment budget for the bay, (3) assessing the effects of shoreline erosion on bay water quality (e.g., turbidity, nutrient loading), and (4) investigating the processes responsible for shoreline erosion.

Digital Geologic Mapping at the Missouri Division of Geology and Land Survey Using ArcView 3 and USGS Digital Raster Graphics

By Edith Starbuck

Missouri Division of Geology and Land Survey
Geological Survey Program
P.O. Box 250
Rolla, MO 65401
Telephone: (573) 368-2136
Fax: (573) 368-2111

The Bedrock Geology of the Forsyth Quadrangle, was drawn into ArcView 3 using USGS Digital Raster Graphics (DRG's) as a backdrop. ArcView 3 is a software program that lets you use and query geospatial information. DRG's are scanned, georeferenced images of topographic maps. This pilot project came about as an attempt to fill the need for a digital product, as well as to ease the production of geologic mapping and create a more versatile product.

Both map producers and users benefit from this method of creating geologic maps. Digital Raster Graphic (DRG) images allow the mapper to use the familiar 7.5' topographic quadrangles in a digital form to plot field (or file) data. This gives the mapper the ability to zoom in on the work area to ease plotting which should increase accuracy. The ability to enlarge, or zoom in, also eases map drawing. The ability to overlay themes, or layers, allows the geologist to compare the map with input data during the review process, and having the map in digital form makes editing easier.

Users, who include a variety of people from developers, to city planners, to environmental site assessors, benefit by having a map that is more versatile and easier to use. The maps can be printed at various scales to provide easy-to-read color maps. More importantly, the map can be used as part of a geographic information system (GIS), so that geologic data can be easily compared to other types of data, such as population or land use. Other digital geologic data can be attached to the map, such as scanned or digital well logs, tabular data such as test results, text such as field notes, or drawings such as measured sections of bedrock exposures. A GIS, including digital maps of bedrock and surficial materials and other related basic data, would give the user greater access to geologic information that could be used in applied projects.

This project is the first at the Geological Survey Program where a DRG image of a topographic map was used to digitize data locations while viewing the map on the computer monitor. This type of data collection is popularly called "heads-up digitizing." It has proven to be an easy and accurate method to plot data that has the potential to be useful in many other types of mapping projects. The ultimate goal is to produce an integrated geologic data package that includes a bedrock geologic map, surficial materials map, and detailed stratigraphic data including well logs and measured outcrop sections. This package would be distributed to users who could overlay their own data (e.g. environmental or cultural features). Potential methods of distribution include CD's, DNR network, or even the Internet.

Montana Bureau of Mines and Geology Poster

By Joel G. Hall

Montana Bureau of Mines and Geology
1300 W. Park St.
Butte, MT 59701
Telephone: (406) 496-4321

The results were shown for several mapping efforts by the Montana Bureau of Mines and Geology. The first two provide examples of digital cartography for 1:100,000-scale quadrangles -- a geologic map with scanned linework shown in transparent mode, and a geologic map plotted with shaded relief topography. The impacts of geologic mapping in Montana were shown for old and new geologic mapping efforts, and their influence on related programs such as ground-water characterization.

New Jersey Geological Survey Posters

Presented by Ron Pristas

New Jersey Geological Survey
P.O. Box 429
29 Arctic Parkway
Trenton, NJ 08625
Telephone: (609) 292-2576
Fax: (609) 633-1004

Dover Township Study Area, New Jersey, Well Head Protection Areas

By Zehdreh Allen-Lafayette, William Mennel, and Steve Spayd


This map was prepared to assist the New Jersey Departments of Environmental Protection and Health and Senior Services in their evaluation of a possible childhood cancer cluster in parts of Dover Township, Ocean County. Ground water from domestic and public supply wells is the sole source of water for drinking and other domestic uses in the study area. Public community supply wells are shown along with their respective Well Head Protection Areas developed from ground-water modeling. The Parkway Well Field was an area of special concern. Some of the wells there were contaminated by the Reich Farms superfund site. Special coverages were developed from ground-water models to show the potential flow pathlines from the Reich Farm pollution plume if the well field was not pumping.

Identified Potential Beach Replenishment Sand Sources, Onshore and Offshore New Jersey

By Zehdreh Allen-Lafayette, Jane Uptegrove, Jeffrey S. Waldner, David W. Hall, Peter C. Smith, Gail M. Ashley, Robert E. Sheridan, Matthew C. Goss, Frederick L. Muller, and Eugene Keller

This map provides a coast-wide summary of onshore sand and gravel sources, known offshore sand shoals, and borrow areas currently being dredged for beach replenishment. The onshore sources are limited to those within 15 miles of barrier island access (due to import costs). Identification of the offshore sand shoals is from work by Meisburger and Williams (1980, 1992), Smith (1996), Williams and Duane (1974), and Uptegrove and others (1995). Borrow area sites are from the U.S. Army Corps of Engineers, General Design Memorandum, Sections I and II (1989 and 1993, respectively).

The lower right inset summarizes beach erosion data compiled from the New Jersey Beach Profile Network, New Jersey Department of Environmental Protection and Richard Stockton College Coastal Research Center.

Alphanumeric identification labels for onshore and offshore sand sources are keyed to volumetric/materials data tables in an accompanying report, "Characterization of sediments in Federal waters offshore of New Jersey as potential sources of beach replenishment sand, Phase II, Year 2 Final Report," available from the New Jersey Geological Survey.


Meisburger, E.D., and Williams, S.J., 1980, Sand resources on the Inner Continental Shelf of the Cape May Region, New Jersey: U.S. Army Corps of Engineers, Coastal Engineering Research Center, Miscellaneous Report 80-4, 40 p.

Meisburger, E.D., and Williams, S.J., 1982, Sand resources on the Inner Continental Shelf off the central New Jersey coast: U.S. Army Corps of Engineers, Coastal Engineering Research Center, Miscellaneous Report 82-10, 48 p.

Smith, P.C., 1996, Nearshore ridges and underlying upper Pleistocene sediments on the Inner Continental Shelf of New Jersey: M.S. Thesis, Rutgers University Department of Geological Sciences, New Brunswick, NJ, 157 p.

Uptegrove, J., and others, 1995, Characterization of offshore sediments in Federal waters as potential sources of beach replenishment sand --Phase I: New Jersey Geological Survey Open File Report OFR 95-1, Trenton, NJ, 148 p.

Williams, S.J., and Duane, D.B., 1974, Geomorphology and sediments of the Inner New York Bight Continental Shelf: U.S. Army Corps of Engineers, Coastal Engineering Research Center, Technical Memoir 45, 81 p.

Ground-Water Recharge and Aquifer Recharge Potential for Cape May County, New Jersey

By Mark French


Ground-water recharge is a quantitative methodology for estimating infiltration of water through the soil to the water table, irregardless of the underlying geology. Aquifer recharge potential is a qualitative methodology for indication of areas of varying potential for recharge to underlying aquifers. Ground-water recharge is estimated using a model outlined in the New Jersey Geological Survey Report, GSR-32 "A Method For Evaluating Ground-Water-Recharge Areas in New Jersey." The model was developed a soil-moisture budget. A simple linear equation is used to estimate ground-water: (Rfactor*Cfactor*Bfactor)-Rconstant

A combination of land use and land cover data and soil data is used to provide the rfactor and rconstant. Cfactors (ratio of precipitation over potential evapotranspiration) are retrieved based on municipality. These values combined with the calibration constant provide ground-water recharge estimates for all areas in Cape May of five acres or greater. These estimates are then ranked, based upon volume to produce a five-tier ranking system.

Aquifer recharge potential is produced by combination of the ground-water recharge areas and aquifer rankings. These rankings were produced using well yield data and NJGS profession staff judgment. Aquifer well yield data were collected from NJGS project databases and USGS GWSI entries. The data were analyzed using median, and numeric and geometric averages. The aquifers were then ranked based upon numeric average. Aquifers having insufficient or no well yield data were ranked by a consensus of NJGS hydrogeologic and geologic staff. Combination of the aquifer ranking and ground-water recharge area data produced a 5 by 5 matrix of aquifer and ground-water recharge rankings. This matrix shows the relationship between infiltration and the underlying geology.

Topographic Bitmap Images for Sussex, Somerset, Cumberland, Hunterdon, Warren, Morris, and Passaic Counties, New Jersey

By Maryann C. Scott and Gregory C. Herman


The New Jersey Geological Survey's Cartographic Section is working with Digital Raster Graphics (DRG) to produce Statewide digital base-map images clipped to county boundaries. We have developed a procedure to scan stable base mylar of United States Geological Survey (USGS) topographic quadrangles and remove foreground image features that extended beyond the county boundary in the Adobe Illustrator program. Next, the image is autocropped to reduce the size of the image in the Vue Print Pro program and saved to the rectangular extends of all positive foreground pixels. Each quadrangle was then geo-registered to the 1983 North American Datum (NAD83) coordinate system in State Plane coordinate feet using the Arc/Info geographic information system. The registration process for each image uses at least four control points located along the image boundary as links to the vector boundary of each clipped tile within its county boundary. The bit map image files use an uncompressed tagged image file format (*.tiff). Each image has a corresponding world-reference file (*.tfw) defining the geo-registration parameters.

As each county base map is complete, it is placed on the New Jersey Geological Survey website. DRG files are reviewed according to standards for New Jersey Geological Survey Open-File products. They are provided at no cost on the Internet as compressed files. The digital bit base-map images are currently available for distribution at the cost of reproduction upon written request to the State Geologist.

North Carolina Geological Survey Poster

By Allan Axon

North Carolina Geological Survey
P.O. Box 27687
Raleigh, NC 27611
Telephone: (919) 733-2423

This poster showed ongoing projects by the North Carolina Geological Survey that are using Arc/Info, ArcView, and MapInfo.

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Last updated 10.06.98