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Digital Mapping Techniques '02 -- Workshop Proceedings
U.S. Geological Survey Open-File Report 02-370

The Value of Geologic Maps and the Need for Digitally Vectorized Data

By James C. Cobb

Kentucky Geological Survey
228 Mining and Mineral Resources Bldg.
University of Kentucky
Lexington, KY 40506-0107
Telephone: (859) 257-5500
Fax: (859) 257-5500


The costs of geologic mapping are challenging to justify. Geologic mapping is supported almost entirely by public funding, but understood by very few people in policy-making positions. The cost is justified for the most part only by anecdotal evidence, such as the discovery of valuable resources, which, when produced, return to society in tax dollars many times the cost of the mapping, or the locating of bridges or landfills so that societal problems are avoided. Public policy-makers want and often demand a cost-benefit analysis to assist in the appropriations process. Only rigorous economic analyses can provide the quantitative data needed to determine a cost-benefit ratio.

What is the value of a 1:24,000-scale geologic quadrangle map? A study based on a survey of professional geologists estimated $43,527! This represents the average amount of money a company would spend to collect the information provided by a published geologic quadrangle map (Bhagwat and Ipe, 2000a, b).

Many geologists and organizations currently involved in geologic mapping are not aware of the Bhagwat and Ipe (2000a) economic analysis. As a result, very compelling data are not being used to justify the cost and purpose of geologic mapping. By citing the enormous economic advantages of having geologic maps available, we can help funding authorities better understand the costs and benefits of geologic mapping. Whenever possible, the value of a geologic map should be cited, as well as the cost-benefit ratio of geologic maps as "public goods."

Few economic studies of the value of geologic maps have been published. Bhagwat and Ipe's (2000a) detailed analysis of the Kentucky geologic mapping program used data from 440 questionnaires and was based on the theory of public goods. Bernknopf and others (1993) also addressed the fundamentals of geologic maps for society, a cost-benefit model for valuing geologic maps, and the economic issues to assess geologic maps as public goods. A study by McGrain (1979) gave examples of the uses of geologic maps, quoted the number of maps sold, and gave anecdotal information about the value of geologic mapping in Kentucky. Cressman and Noger (1981) cited many facts and figures about the 18-year geologic-mapping experience in Kentucky, including history and origin of the program and technical, scientific, and personnel challenges. Although they alluded to economic benefits of the Kentucky geologic mapping program, they did not perform a rigorous economic analysis.


Subhash Bhagwat and Viju Ipe, economists with the Illinois State Geological Survey, focused their study on Kentucky because it has been completely mapped geologically at a scale of 1:24,000 for 25 years. They worked with staff of the Kentucky Geological Survey to create a questionnaire that would elicit responses suitable for quantitative analysis of the value of geologic maps. Because the questionnaires were being sent to registered professional geologists, other information about the uses of the maps and preferences of the users was requested. The questionnaire contained 14 questions that asked for information such as: The questionnaire was sent to 2,200 geologists registered in Kentucky. This pool of 2,200 included actual and potential users of geologic maps. The response rate of 20 percent (440 responses) provided a representative sample of the user population. Data were extracted from the questionnaires into a database and for qualitative and quantitative analyses. A complete description of the data and the analytical methods is given in Bhagwat and Ipe (2000a).

Value of a Geologic Quadrangle Map

Bhagwat and Ipe (2000a, b) determined the value of a 1:24,000-scale (7.5-minute) geologic quadrangle map to be $43,527. The respondents to the questionnaire said they saved this amount, on the average, because the maps were already available and therefore they did not have to collect the data themselves. Similarly, respondents reported that to collect only a minimum amount of information for a credible job would have cost an average of $27,776. Because the questionnaires were directed to Kentucky registered professional geologists and were concerned with the Kentucky geologic mapping program, these value are specific to Kentucky GQ's, but could certainly be extrapolated to GQ's in other states, especially those with similar geology.

Value of Geologic Maps Kentucky

Bhagwat and Ipe (2000a, b) calculated maximum and minimum values for the statewide mapping program by multiplying the number of maps sold (81,000) by the maximum ($43,527) and minimum ($27,776) values per map. This results in a maximum value to the state of Kentucky of $3.53 billion and a minimum value of $2.25 billion. These values are 25 to 39 times the cost of the mapping, giving a tremendous return in value to the State for the cost. A cost of $90 million (1999 dollars) resulting in a benefit of up to $3.35 billion is a remarkable return on the taxpayers' investment! The public has been extremely well served by the mapping program, as demonstrated by this cost-benefit analysis. Even if you have never purchased a geologic quadrangle map, you still benefit from the availability of the maps to society. This is because economists consider GQ's "public goods," much the same as roads, dams, and reservoirs are--in fact, GQ's make it possible to build better roads, dams, and reservoirs, and build them more economically. And the public will continue to reap the benefits of the maps, because the information they contain will continue to be used for many more decades.

Reported Uses of Maps

The responses indicated a wide variety of uses for the maps, some of which could not have been anticipated at the time the mapping program began (Table 1). Some of the most common uses were:

Table 1. How people use Kentucky geologic maps (from Bhagwat and Ipe, 2000a).

Category Map use Percent of
Exploration and
Oil and gas
Industrial minerals
Ground water
Pollution prevention
Industrial applications
Site clean-up
Hazard prevention
and protection
Karst problems
Engineering Buildings and foundations
Roads and highways
Dams, dikes, and locks
City planning Zoning decisions
Landscape planning
Building codes
Regional planning Waste disposal
Industrial permits
Property valuation Property tax assessment
Land acquisition

The user responses indicated that GQ maps are used in nearly all sectors of the economy to ensure environmental safety, to prevent hazards to manmade structures, and to delineate and develop natural resources such as ground water, minerals, and fuels. The use of GQ maps improves the quality and credibility of work and saves money. Most important, geologic mapping generates knowledge--a public good vital to the economy, public safety, and public health. This knowledge would not be produced if left to private enterprise and has not been produced by private enterprise elsewhere, except on a site-specific basis or under contract to a public agency. In such cases, the resulting maps remain in proprietary or private hands and are not available to the public. Map users indicated the desirability of maps showing lithology, structural features, formation contacts, and cultural features. The most desired map scale was 1:24,000.

Intangible Benefits

A section of the cost-benefit study was devoted to intangible benefits derived by map users. They include such vital benefits as increased credibility in reports and studies prepared by map users, time saved in project completions, and the value of unbiased information in maps that were prepared by scientists without a vested interest. These kinds of intangible benefits often outweigh the monetary value of public goods. Such benefits are especially important in the case of public goods that create and deliver scientific knowledge, in contrast to public goods that provide physical facilities of economic or recreational value, such as parks, roads, or bridges.


In the 160-year history of the Kentucky Geological Survey, its most valuable accomplishment has been the geologic mapping of the state at a scale of 1:24,000. The 707 geologic quadrangle maps are the Survey's greatest assets and were the result of a 20-year cooperative program with the U.S. Geological Survey. The mission of the Kentucky Geological Survey has been and continues to be investigating the geology and minerals of the Commonwealth for the benefit of its citizens. The geologic mapping program, which started in 1960 and finished in 1978, not only advanced this mission, but also contributed to all future work by the Survey and other agencies involved in mineral resources, water, geologic hazards, environment, construction, and land-use planning. The Kentucky Geological Survey owes a great debt of gratitude to the U.S. Geological Survey for its cooperation while the program was underway. The successful completion of this program is a tremendous testimonial to the planning, foresight, geologic and administrative effort, and cooperation of these two organizations. Demand for the maps has been strong. More than 5,000 geologic quadrangle maps are sold to the public each year, and the initial printing of a number of the GQ's has sold out completely. A number of remarkable benefits from these maps are not readily apparent.
  1. The cost of the mapping program in Kentucky was justified, if only for the economic development of oil, natural gas, coal, and minerals. The economic development of these natural resources was made possible by the valuable information these maps contain. Kentucky's mineral economy rose dramatically in the 1970's and 1980's, especially in the areas of industrial minerals, coal, oil, and gas. What could not have been anticipated in 1960 when this mapping program began was that the use of these maps 30 years later for the management of land, water, and the environment would surpass their use for mineral development. In a society where landowners are responsible for their land and water, making information readily available for the prudent use of those resources is not only important, it is essential.
  2. The geologic maps provide knowledge about the land and geology for a broad cross section of users in society (e.g., researchers, engineers, miners, urban planners, and hikers). In fact, there are so many diverse users that listing them all is almost impossible.
  3. If a picture is worth a thousand words, then certainly a geologic map is worth a million words. For the tens of thousands of requests that the Kentucky Geological Survey receives each year from the public about land, water, minerals, and hazards, the geologic maps are sufficient to respond to a great number of them. For requests for which more detailed information is needed, the geologic maps provide a context or base of understanding for more detailed data and analysis.
  4. Following the completion of the geologic mapping program in 1979, a new state geologic map published at a scale of 1:250,000 became a popular map for statewide analysis and study. A geologic map published in 1988 at a scale of 1:500,000 also became popular for regional resource assessments. The publication of both of these maps was made possible by the existence of the original detailed geologic maps at a scale of 1:24,000.
  5. Currently, the 707 geologic quadrangle maps are being converted into digital format for use in a wide variety of computer applications. Scanned versions of the maps are available for the public to view and print from the Kentucky Geological Survey Web site, and digitally vectorized geologic quadrangle data are made available on CD-ROM. Vectorized and attributed geologic quadrangle maps will be available in the near future for use in geographic information systems. This will make detailed geologic information available for every office and home over the World Wide Web, 24 hours a day, 7 days a week, for use with decisions requiring geologic information.
What started 40 years ago as a program to spur the economic development of the mineral and fuel industries of Kentucky has proven to be enormously valuable in many other ways in both the public and private sector. The forethought of the Tenth Kentucky Geological Survey to commit itself to that challenge and to complete the geologic mapping program is a legacy whose value should never be underestimated. I cannot describe in stronger terms what a valuable resource the geologic maps have been and continue to be for the Kentucky Geological Survey and the State.


Many states are digitizing old and new geologic maps so that they can be used in computer programs and plotted on demand or transferred electronically as needs arise. Bhagwat and Ipe's (2000a) research indicated broad support for the creation of digital products. An overwhelming 82 percent of respondents agreed that digital geologic maps are valuable to them. The user community also needs help learning how to use the associated computer programs. To the extent possible, every state engaged in the production of digital geologic products (including maps) should help the user community learn applications that manipulate and use the data.

The Kentucky Geological Survey is publishing digitally vectorized geologic quadrangle data (DVGQ's). The DVGQ's are the line, point, and attribute data from a 1:24,000-scale geologic quadgrangle map. The philosophy driving the DVGQ's is that potential users will fall into two categories: they will either need a paper map, or they will need specific parts of the map in digital format to be cut and pasted into their own work. A user who wants a paper map can request one, and a user who needs the computer data can get them from the DVGQ. The DVGQ gives the user all the files from which to select a specific element from the map. This eliminates the need for the user community to vectorize geologic map data and risk introducing errors. Still, making the user community aware of the DVGQ's and teaching them how to use the data is a big job. For this reason, the Kentucky Geological Survey, and other geologic groups and societies, host workshops and short courses on the use of DVGQ's.


A total of 46 states had geologic mapping projects under the STATEMAP section of the National Cooperative Geologic Mapping Program in 2001. The total funding for this national program in 2001 was $6.7 million, which is roughly equivalent to what was spent per year, adjusted for inflation, for geologic mapping in Kentucky in the 1960's and 1970's. Clearly, work still needs to be done to increase funding for a program as vital as STATEMAP. The outstanding benefits of this program, when compared to the cost, make it an important public investment.


Bernknopf, R.L., Brookshire, D.S., Soller, D.R., McKee, M.J., Sutter, J.F., Matti, J.C., and Campbell, R.H., 1993, Societal value of geologic maps: U.S. Geological Survey Circular 1111, 53 p.

Bhagwat, S.B., and Ipe, V.C., 2000a, The economic benefits of detailed geologic mapping to Kentucky: Illinois State Geological Survey Special Report 3, 39 p.

Bhagwat, S.B., and Ipe, V.C., 2000b, What are geologic maps worth: Geotimes, December 2000, p. 36-37.

Cressman, E.R., and Noger, M.C., 1981, Geologic mapping of Kentucky--a history and evaluation of the Kentucky Geological Survey-U.S. Geological Survey Mapping Program, 1960-1978: U.S. Geological Survey Circular 801, 22 p.

McGrain, P., 1979, An economic evaluation of the Kentucky geologic mapping program: Kentucky Geological Survey, ser. 11, 12 p.

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