I held my hand against a small, white dot I just painted on the wall of the cave passage. “Hand on station,” I called back to my partner Cindy, who began measuring the survey shot between us. A stream silently rolled through the cave, filling the passage from wall to wall with knee-deep water. Just above freezing, the water slowly seeped into my boots and my toes started to lose feeling. I had the sense to don my thick wetsuit for this outing but erroneously omitted my neoprene socks. As the bright, red dot of a laser bounced around on my hand, I wondered where my life went wrong, and how that wrong turn enabled this experience to be what some people refer to as fun.
Despite the ups and downs, this experience was part of a grander, and more fun, project to map caves. The privately owned cave we were in had been closed for some time. After a few months of groundwork, we negotiated access for a resurvey project—a process where we explore the known and unknown passages of a cave to further map its features. Landowners, frequently suspicious of people who wish to crawl into holes in their backyards, are often put at ease upon being shown the results of a cave mapping project.
A large surface stream entered this particular cave, rendering it prone to flooding. Hence, there I was, toes going numb in 33-degree water while I installed a water depth probe. The probe recorded the depth of the water in the cave every fifteen minutes from when we installed it in February to July, allowing us to examine when and how the cave floods.
This cave also blows out warm air in the winter, indicating that it had another entrance and unexplored terrain, but we barely noticed the relative warmth compared to the underground stream in which we stood. We just finished surveying the known reaches of the 300-foot passage when we decided to stage a photograph at the bottom of the entrance. I fumbled with my camera, more focused on my relative discomfort than the photograph, completely unaware of what I was about to experience.
As I backed up to shoot the photo, I kicked a rock behind me and heard it fall a few feet, bounce, then fall for a substantially longer period before landing in the black void below. I quickly ignored the photo and began shifting rocks aside to reveal a drop down a narrow slot canyon whose walls were covered in razor-sharp, scalloped edges. I tossed the rope down the slot and rappelled in to find myself on the pristine, muddy banks of an old lakebed.
There were no footprints in sight. I hesitated a moment so I could relish what was about to come. My next steps would be the first ever taken in this place by a human being. We were trailblazers in this underground room and had the responsibility of setting the path for those who would follow us. Every footstep had to be intentional.
The truly adventurous experience of exploring an unknown cave can only be described in cliches. It is one of the last frontiers of modern exploration. It is dangerous, uncomfortable, and exhausting. It is exhilarating, frustrating, and addicting. The places cavers visit for the first time are less known than the surface of the moon.
For cave mappers, the thrill of discovery yields to the satisfaction of understanding how this new piece fits into a larger underground puzzle. Foot by foot, cavers take hundreds or thousands of pages of notes, systematically measuring, drawing, and recording every feature within a cave. On the surface, this data is entered into a computer and a map is produced that features information about navigation, geology, hydrology, and history.
In July, I found myself back at the cave in which we installed the water depth probe. I traded 25°F air temperature and snow for an 88°F day with oppressive humidity. I had my wetsuit again, but it stayed in my pack as I fought my way through briars to the entrance. The stream at the cave entrance was a balmy 78°F.
My friend Riannon and I were on a trip to remap passages down the main trunk of the cave. This adventure was a resurvey, which is the necessary process of remapping areas that have previously been mapped in order to continue mapping unexplored passages further into a cave. The notes and data from the last mapping in the 1980s had been long lost to history, so we were beginning from scratch, except for the mere 200 feet of passage that I had mapped while installing the probe in February.
“Hand on station,” I said again as a red dot bounced around the walls. Riannon pointed a DistoX2 unit, which is a beefed-up laser rangefinder that we use to measure the distance and direction between survey stations underground. After a couple of shots, she read the information to me and I wrote it down. Standing comfortably in the stream, warm and cozy this time, I began mapping while remembering less pleasant surveys from years past.
Shot by shot, we continued forward into the cave. Even though we weren’t experiencing an undiscovered cave, we relished in documenting the geology—specifically the rock strata or layering in which the cave was formed. The rock units, or geologic formations, here determine where and how the cave was created.
Water enters the cave entrance along a thick layer of limestone and sits on top of a layer of sandy, limey rock, which the water cannot easily cut down through. From there, the water breaks into a massive slab of limestone and drills straight down through it, forming large, vertical shafts in the rock. The cycle repeats, cutting vertically through each layer of limestone and moving horizontally along each layer of sandstone and shale. These rock layers, when recorded in the survey, provide crucial insights into how the cave behaves along with clues about where more cave passage might be found.
I recorded this information in my notebook and began drawing. Sketching in a cave is a rather unique activity that many cavers transform into a hobby of its own. I started the map by using a ruler and protractor to draw the survey line that we just measured. Then, I drew the cave around the line, using dimensions from the DistoX2 unit and dead reckoning—estimating the position and size of objects from adjacent points. Great cave maps are created by meshing objective scientific documentation and subjective interpretation.
This data was then entered into a computer and the sketches scanned to allow the final map to be drawn digitally. Trip by trip, the cave map gets drawn this way. The cartographer, however, can only provide as much detail in the final map as I provided in my sketches. There’s a fine balance between drawing the cave as detailed as technically possible, deciding which features to exclude, and managing the time and effort spent on each survey shot. In this case, I was both the sketcher and cartographer, simplifying the working relationship.
Back at home, I sat at my drawing table in the living room. My method for cartography begins with printing the line plot—a digitally compiled series of lines produced from a survey. I overlayed my cave sketches on top of the printed line plot on a backlit table and manually redrew the cave, first in pencil and then in ink with technical pens. The inked panels were then scanned into a computer and placed into the final map, where I digitally added finishing touches like text, color, and graphics.
I only use this approach for my personal projects. Maps created with collaborators are always done digitally from start to finish, where the survey notes get scanned into a computer, a program morphs the sketches to the line plot, and a cartographer digitally traces over all of it. Regardless of how a cave map is produced, the process continues in a grand cycle. At the end of a cartography session, the cartographer is left with a map of a cave that often has at least one passage ending with a big ‘?’ graphic.
And with that ‘?’, we plan our next phase of exploration. Using the knowledge and experience gained on previous trips, we can plan easier and more efficient ways to reach the end of the cave. We often venture into the depths solely on a mission to set new ropes or stage gear. Just a few hours of prep work can save hundreds of hours on future trips, translating to hundreds of hours of cold, wet fun pushing that ‘?’ further into the unknown.
Author’s note: To protect the stunning geologic, biologic, and cultural resources in caves, I cannot release the names or locations of sensitive areas in this story. However, I can assure you that these underground wildernesses really do exist beneath our feet. Ryan Maurer is a photographer, caver, and writer from Southwest Pennsylvania who now lives near Annapolis, Maryland. When not underground, he spends time planning his next trip underground.
