The SURVEY in Missouri Speleological Survey

The primary mission of the MSS has always been cave survey, the art and science of documenting a cave with reports, photographs, sketches--and maps. While the first three documents may be very useful, a cave map is invaluable for many reasons. First, it enables someone unfamiliar with the cave to navigate through it with a fair expectation of knowing where in the cave they are, and how to get back to the entrance. Actual wall dimensions, stream measurements and landmarks underground are used. You can look at a well made map, look at your surroundings, and find out easily your location. Cave maps are quite useful in cave rescues, in land disputes where multiple owners may own the land over the cave, and as documents of the extent of exploration. Cartography, the study of mapmaking, also can be done with an eye to the aesthetic values of the map, as well as the accuracy.

The earliest cave maps were sketch maps, usually not to scale, and drawn from memory. These were rarely accurate.

Actual measured maps using hand surveyor's tools of compass and tape are most common--these tools are inexpensive, can be used with accuracy, and have the best chance of survival in the cave environment. Inclinometers can be used to add a third dimension to the usual plan view cave map (view looking down on the cave) by adding profiles (view as if the cave were sliced vertically) to the map. Many standard mechanical above ground survey tools cannot be used in a cave effectively. A 4 foot high tripod-mounted transit cannot be used in a 2 foot high watercrawl, for example. In the early 1960's, the MSS set the national standard for cave mapping symbols--a cross between surveyor's marks, and geologic notation.

Modern survey tools including electronic laser rangefinders whose data is fed directly to portable computers have come on the scene recently, and have established new standards of accuracy for cave maps. Many project caves with tens or hundreds of miles of passage and multiple survey crews and trips have been mapped using these methods because of their consistency of data output.

Total stations, laser theodolites, and other commonly used, high tech survey devices often are not suitable for water crawls and adverse cave conditions of wild caves, and are beyond the financial means of volunteer surveyors. Much more common is a hybrid system, where measurement by traditional hand tools and simple rangefinders are used to generate numerical x,y,z coordinate data. These data are then input to computer drafting programs, with additional detail added with graphics programs. Maps produced by these means are more standardized than traditional maps hand-drawn on mylar or drafting film. Since maps are produced for different reasons, the advantages of a mechanical drawing or an artistic rendering can be weighed, where in the past mere accuracy and legibility were the chief goals.

Cutting edge maps may not use paper at all, but be virtual reality computerized video, combining video images with superimposed measurements, and recreate on the screen the experience of moving through the cave.

If you are interested in the basics of cave mapping, several issues of Missouri Speleology deal with the subject. The latest one, The Art of Cave Mapping, was published in 1991, and is still in print.

2003 Jo Schaper.

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