From Compass & Tape, Volume 11 Number 1,2 Issue 36 Summer, Fall 1993


by Bob Hoke

Every now and then Murphy’s Law is violated, and everything seems to go right. This paper describes a cave survey project that ran exceptionally smoothly and avoided most of the pitfalls that seem to snag most large cave surveys.

Paxtons Cave is a popular maze cave in Allegheny County, Virginia. The cave was mapped in the 1970’s, but the map was incomplete, inaccurate, and generally in need of a major update. An informal group of cavers from the Washington D.C. area and eastern Virginia decided to remap the cave. Tom Kaye agreed to do the data processing (using Bob Thrun’s CMAP program) and Tom Spina agreed to do the drafting (using the traditional pen-on-paper technology). The project was not associated with any specific caving organization, but instead was genuinely open to anyone who wanted to participate.

The Paxtons Cave Project started in August 1988, and the final survey trip was made in February 1990. Prior to the project, the cave was reported to contain 3.2 miles. The new map showed the cave as having grown to 7.2 miles. (Our secret dream of discovering tons of virgin passage was never realized). There were a total of 2,675 shots in the survey.

The following is a list of some of the things that seemed to contribute to the success of the Paxtons Cave Project. The list is in random order. Of course, most items may not apply to every cave, but the list should provide some insight into things that have worked.

Pick a cave that is interesting and an “appropriate” size

Paxtons is a 7-mile maze cave with a reasonable number of formations. It is large enough to be challenging, but small enough to be completed in a finite time. When the project started we estimated that it would take about 2-3 years to finish if we surveyed once a month. Our time estimate was correct, but only because we had lots more participation than we anticipated and we were able to put multiple survey teams into the cave on virtually every project weekend. The moderate duration of the project meant that it was long enough to have continuity and attract new participants, but short enough that the folks who started the project were still around at the end.

We had some 32 project weekends, with a total of 90 different participants. We managed to put six survey teams, with over 25 surveyors, into the cave on a couple weekends. Several people were on only one trip, and one person was there on all 32 weekends. There was a “hard core” of about 12-15 people that participated in more than 2/3 of the trips.

Set and maintain high survey quality standards

We surveyed EVERY passage, closed EVERY loop, did compass and clinometer backsights for (almost) EVERY shot, and promptly resolved EVERY loop closure or sketching problem. We tried to have our front and back readings agree within 2-3 degrees. This consistent level of quality probably scared a few sloppy surveyors away, but there was a general agreement among the participants that we wanted an accurate survey. The standards were set and maintained by consensus, not by edict.

Do high quality in-cave sketches to a consistent scale

We generally used clipboards and 8″x10″ sheets of Mylar for all sketches. In-cave sketches were at 20 feet/inch and the final map was at 30 feet/inch. (We are not sure where the scales of 20 and 30 feet/inch came from, but Tom Spina was doing the final map and he insisted on those scales). The sketcher used a compass and protractor to plot the survey data on the Mylar, so the resulting sketches were essentially complete, accurate sections of the map that required relatively little conversion when they were added to the master map.

One well known eastern caver was used to doing “schematic” sketches in the cave and then tuning them into award winning maps in the privacy of his own home. He found it impossible to do a “real” sketch in the cave and made only token appearances at Project weekends. (His method is fine as long as he is doing both the in-cave sketches and the final maps. His shorthand technique does not work when someone else is doing the final map).

Set trip dates well in advance and stick with them

We generally had one trip per month and the dates were published in club newsletters in plenty of time for people to know what was coming up.

Have open trips and willingly train novices

It is tempting to make a survey project the exclusive domain of experienced surveyors. However, we were willing to train new people, even though it frequently meant that the team doing the training was not as productive as the other teams that day. This policy resulted in one new surveyor becoming one of the most active members of the project, and a number of others made valuable contributions to it.

Promptly reduce the survey data to detect blunders

Our trips were always held on Saturday, and Tom Kaye spent Sunday evening reducing the new data. He was able to resolve any problems while the trip was fresh in everyone’s mind, and this meant that we had very little need to field check the data on subsequent trips. Tom was normally able to debug the new data, integrate it into the computer data base, and have updated line plots in the mail to Tom Spina (the project’s cartographer) by Monday morning.

Have updated maps segments and raw survey data available to EVERY survey team

Prior to entering the cave each survey team was normally given a current map segment with all leads marked and a computer print with the raw survey data for the area the team was going to. This allowed the team to easily find its tie-in stations and quickly get their sketch started. This also let the people from the previous month’s trip see what there data ended up looking like. People like the feedback of seeing their effort getting onto the master working map.

Maintain interest in the project by writing interesting trip reports

It is not easy to write a trip report for 32 trips to the same cave, but doing so will help maintain awareness of the project and encourage participation. We probably wrote some sort of article for about 2/3 of the “official” project weekends. Reports are especially easy to write if something interesting or humorous happened, or if some significant milestone was reached.

Near the end of the project we had a “final” trip to finish the survey, and this naturally was written up in the newsletters. However, we subsequently had several more “final” trips to finish up a few areas. The constant notice of upcoming “next final” trips actually generated additional interest in the project because everyone was wondering when the final “final” trip would occur. All this foolishness made it relatively easy to write newsletter articles near the end of the project.

Avoid booty scooping

We were quite successful in using peer pressure to enforce the rule that you always survey the passage closest to the entrance. This means that each team eventually got its share of both borehole and mud crawl. Our success with this policy meant that when an area was surveyed it was unlikely that any leads were left that would never make it onto the final map.

Figure 1 shows the progression of the survey at various points in the project. The important thing to see in the progression of maps is that the cave grew rather smoothly instead than having a lot of trunk passages surveyed early in the project and all the sleazy passages left for last. We saw just as much trunk passage on the last survey weekend as we saw on the first (well, almost as much).

Avoid a dominate personality who becomes a dictator

It is important to have one or more people who serve as the focal point of a project, but the project will die if someone assumes the role of dictator and turns everyone else off. We had 3-4 people who seemed to serve as co-leaders of the Project at various times. Somehow, there were virtually no personality conflicts and everyone is still on speaking terms now that the project is completed.

Keep track of all data and sketches

After each Project day, the survey teams met at a local pizza joint for dinner. Tom Spina took the Mylar sketches with him, and Tom Kaye took the books with the day’s data. Kaye then processed the data, and sent Spina line plots and xerox copies of the data from the survey books. The actual books were given back to their owners as soon as Spina received the copies. Spina kept the Mylar sketches. This systematic approach seemed to eliminate the usual problems of lost data or sketches.

Have fun

Overall, the Paxtons Cave Project was a medium duration mapping effort that seemed to run exceptionally smoothly. The points discussed in this article certainly contributed to the project’s success and smooth operation. However, perhaps the most important overall contributor was the fact the participants realized the project for what it really was: a hobby. The trips were rather low key and people seemed to enjoy participating. Caving is a hobby for most people, and the project’s combination of low pressure and reasonable quality standards seemed to encourage participants to “go with the flow” rather than fight the system.

For more information about the Cartography Section of the NSS and its publication, Compass & Tape, contact Bob Hoke at

Credit to: the Gangsta Mappers Home Page