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 Published by the American Geological Institute
November 2000
Newsmagazine of the Earth Sciences

Mapping the Outcrop 

By J. Douglas Walker 
and Ross A. Black

Teaching field geology with laptop computers and geographic information systems brings digital mapping to the outcrop.
Above: Students scope the area and enter data into their laptops. Photo by Anthony Walton.
Over the last 20 years, geologists have evolved from die-hard computer-phobes to people using computers in virtually every aspect of their work. Now computers are making inroads into that last bastion of the “old-school” geologist: basic field mapping on the outcrop.

A field mapper can still pull on a pair of boots and grab a backpack, hammer and base map and conduct field work without a computer. Even with the advent of the personal computer, most outcrop mappers remain independent, self-reliant and proud of the low level of technology necessary to make original geological contributions to the scientific community.

But computers have become ubiquitous within our society. This is especially true in higher education. Today’s student has been exposed to computers since an early age, and many students now actually see computers as a primary learning tool. Who better, then, to test digital mapping technologies than students? Over the last two years, we have been teaching our geology students to use laptop computers and geographic information system (GIS) software in the field.

Mapping itself is becoming a digital process (Geotimes, June 2000). With the advent of the Internet, we expect new scientific information to be digital. Large corporations, government agencies and, to some extent, universities began major efforts to put new information into a digital form many years ago. They also had to come to grips with the fact that it is tedious and expensive to convert older data into a usable digital form.

Entering historic data into a system where it can be integrated with other information is a chore. Entering mapping data into the computer is one of the geologist’s more onerous tasks. The endearing term “digi-slave” is common in laboratories and offices converting maps into digital data sets. Making mapping information digital from the earliest point of the mapping process — in the field — could save the mapper many time-consuming steps.

Geological data are location dependent: the elevation and location at which an observation is made is just as important as the observation itself. This is why most geological data are recorded in a map-based format. Geological outcrop observations are thus well suited to being recorded and manipulated with existing GIS software packages.

We and our students use GIS software to compile, compose and view geologic maps. We also use such software to merge maps with satellite imagery, aerial photography and other data sets, and for visualizing data in 3-D for modeling geological processes.

Our GIS lab has been integrating large geological and geophysical databases for the last six years. We have put a tremendous amount of time and effort into converting paper-based geological data into a digital form.

Existing geological maps are by far the hardest sources of information to enter into a database. The information on the map consists of on-the-fly interpretations of observations the field geologist made on the outcrop. The person digitizing the map must also interpret the map symbols on-the-fly.

Why not enter the data into the GIS package on the outcrop, eliminating the need for another step in the lab that is technical, time consuming, costly and prone to error?

After asking ourselves this same question, we started putting together a computer-based field-mapping program. Several private companies, government agencies and academic groups were  pursuing the same goal, and we met them at meetings of the Geological Society of America, American Association of Petroleum Geologists, American Geophysical Union and the Environmental Research Institute Users Group. Some groups, most notably the Canadian Geological Survey, Bowling Green State University and the University of California at Berkeley, had digital mapping programs in place. But almost everyone was at about the same stage we were.

We investigated the technologies we could pursue and then sought funding for the project. We received funding from the University of Kansas (KU) Technology Fund, the Geothermal Program Office of the U.S. Navy and the KU Department of Geology.
Students in the field

We first used the computers and software in a graduate level mapping course offered in January 1999. Four graduate students signed up. These students had previous mapping experience, and three of the four had used ArcView software.

The students first had to figure out how to carry their laptops into the field. They dug into a box of straps, buckles, clips and tape we had purchased from a camping store, and, after an hour of fiddling, were ready to go into the field. Most of the first day was spent getting used to the computers and trying to enter geologic data on the outcrop.

In a word, the students were very unhappy with the whole operation at the end of the day (mutiny might be a more accurate term). Carrying the nine-pound computers was not fun, digitizing was a pain, the screens were hard to read and the batteries were weak and heavy. We were not very encouraged. 

   Students using computers during a University of Kansas field
   camp. Photo by Anthony Walton.

To avoid a total loss of field time, the students printed maps and took them into the field to map on the next day. This went fine until it came time to enter the data into the computer. Predictably, this was a tedious operation. Sensing that the computers could actually save some time and effort, we went out with computers and paper maps the third day. By the end of the day the students were mapping pretty well on the computers and were in better spirits.

We spent another seven days in the field mapping and working out problems with the computers and software. By the end of two weeks, three of the four students were happy with the mapping setup. The fourth remained unconvinced that we had come up with anything useful.

After this session, it was with great uneasiness that we introduced computer mapping into our undergraduate field camp in June of 1999. We taught eight undergraduate students in the last week of a six-week field course. None of them had ever used a GIS program, let alone ArcView. We gave them the same short, three-hour introductory session we’d given the graduate students and then sent them into the field.

The undergraduate experience could not have been more different from the graduate one. The students were very excited about mapping with computers and welcomed the change from paper maps, photos and mylar overlays. Most students were comfortable with the computers by the end of the first day; by mid-morning of the second day they were asking questions about the geology and not about how to use the programs.

We attribute these different reactions to two factors. First, the undergraduates are not set in their ways about mapping. They did not have the background baggage the graduate students carried. Second, the undergraduates were more used to computers. The age difference of a couple of years is just enough that the younger students expect to use computers in all aspects of their education and most aspects of their lives.

The future

We will continue using computers in University of Kansas field courses. We plan to expand the undergraduate component to about half of the six-week course. We still consider conventional mapping skills important. Introducing the computer adds a level of excitement for the students.

Many of our students are now taking GIS courses. This change is a grassroots effort among the undergraduates and not an idea the faculty pushed onto them. They will know more about the basic software components than will some of the field-camp faculty members.

Some of the problems with field computers are being remedied. Laptops are getting lighter — four pounds instead of nine pounds. Battery life is steadily increasing. We can map all day on a single lithium-ion battery. Touchscreens are now readable in sunlight. Personal digital assistants should soon be powerful enough to run the software and handle the large image files needed to perform efficient mapping.

The widespread availability of inexpensive (or free) 7.5-minute topographic maps in various digital formats has been one of the important factors in making digital mapping systems easier to use. Now we need inexpensive, large scale, aerial photos at digital resolutions useable for geological field studies.

The final component for digital mapping is GPS receivers. Using the Global Positioning System (GPS) promises to give the field geologist real-time, accurate location information. Although we have a method for connecting the GPS unit directly to the laptop and downloading the location, the GIS packages do not automatically update the map with the proper map symbols. Thus it is easier to read the location from the GPS unit and then manually move the laptop cursor to that point on the map and record the field observation. We hope that GPS receivers soon become standard options for ruggedized laptops and that GIS packages include easy-to-use interfaces with standard GPS data.  The demise of selective availability in GPS signals (Geotimes, June 2000) has made GPS coordinates almost 10 times more accurate.

Improved, publicly available GPS signals my be what pushes GPS/GIS-driven geological field mapping onto every student’s field belt in a one-piece unit that will fit in a Gfeller field case.

Tools for Digital 
Field Mapping

   Rocky II field computer with Garmin GPS unit.
   Hammer for scale. This computer weighs about
   9 pounds and is equipped with two batteries.
   Photo by Douglas Walker.


Several companies manufacture field-hardened, ruggedized laptops, mainly for the military and forestry markets. Requirements include: a keyboard sealed against the elements; a screen that is readable in direct sunlight; and a metal body. 

The most rugged of the machines we use survived the full force of a graduate student falling directly on the laptop. The handles and the screen hinges are usually the points that fail under strain. Internal drive bays are convenient for saving and moving data, but add cost and weight to the system.

Battery life is usually overrated. By trial and error, we learned to use all of a computer’s power saving features that are normally ignored. The “suspend” command under Windows was the most valuable.

A stable, readable touchscreen is useful but often expensive.

Other necessary hardware is a Zip drive for nightly backups and a printer for producing maps.

Useful Global Positioning System (GPS) receivers are the small hand-held units and the larger dome-mounted, real-time differential units. The hand-held units are light and accurate enough for geological mapping, especially since the U.S. government removed selective availability from the GPS signals earlier this year (Geotimes, June 2000). Without selective availability, most hand-held GPS units have position errors of approximately 10 to 15 meters — a sharp pencil line on a 7.5-minute quadrangle map equates to about 7 meters. Most likely, expensive real-time differential units are now unnecessary.


Each computer operating system dictates the available software. Although our GIS lab is mainly Unix-based, we use Windows-based computers in the field. In the lab we use the entire suite of ESRI, ERDAS and Adobe products for GIS, remote sensing and finished graphics applications. In the field we use ESRI’s Arcview. Other useful packages are MapInfo, PenMap and various programming languages, such as Visual Basic and Avenues.

The main flaw in Arcview is that it does not automatically merge boundary line segments (arcs) into polygons. Students map only the contacts or boundaries of geological features, and then later must merge them into rock unit polygons. The Edit Tools software merges the segments, thus expanding the feature editing we can do.

The GeoClassifier, written by University of Kansas students, adds standard geological attributes to point, line and polygon data with a set of drop-down menu buttons large enough to read in the field. We use this extension in our laboratory for assigning attributes to digitized maps.

The GeoEditor, also a student creation, is similar, but incorporates support for GPS units that can generate an output stream of NMEA-104 ASCII text over a serial cable.

When the mapper chooses a point, a Visual Basic routine reads the data stream from the GPS unit, parses out the coordinates and passes it to the Arcview extension, which creates a location point in the database.

Download the Edit Tools extension to Arcview from Download GeoEditor and GeoClassifer from

Additional Reading ________________________________________________

“Bedrock geologic mapping using ArcInfo” by T.E. Wahl, J.D. Miller and E.J. Bauer. Proceedings of ESRI Users Conference, 1995. p. 167.

“The Bedrock of Geologic Mapping” by P. Chirico. Geo Info Systems, 1997. v. 7, n. 10, p. 26-31.

“Development of Geographic Information Systems Oriented Databases for Integrated Geological and Geophysical Applications” by J.D. Walker, R.A. Black, J.K. Linn, A.J. Thomas, R. Wiseman and M.G. D’Attilio. GSA Today, 1996. v. 6, n. 3, p. 1-7.

Getting to Know ArcView GIS by ESRI Press. 1998.

Walker and Black teach in the Department of Geology at the University of Kansas in Lawrence, Kan.

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