Feature: Surveying Goes Underground
Professional Surveyor Magazine - February 2004
Surveying is, at its heart, exploration. While day-to-day surveying tasks may not cover "new" ground, the basic needs-and desires-behind surveying remain the same as they were for Lewis and Clark, Mason and Dixon, and other explorers throughout history: see new places, bring back valuable information, lead the way for others. Today, everyone from National Geographic exploration teams to loosely organized groups of weekend warriors are out there making news as modern-day explorers. And surveying plays a central role in their explorations-as do surveying tools like the rugged Recon handheld from Tripod Data Systems. Because even the oldest quest is made easier with the newest technology.
Step 1: Find Uncharted Territory
The actual number of unexplored areas left is dwindling rapidly. Want to bag a new peak? Better head to Antarctica, or maybe the Brooks Range in Alaska-and have fun getting to either of those places. Maybe the wide-open desert is more your style. But how would you really know for sure that no one had stood in that spot before? If it's been mapped, odds are someone's already been there.
Perhaps the answer lies beneath your feet. Well, that depends on where you're standing. But if you want to go somewhere no one's ever been, a good avenue to pursue would be discovering a cave.
Some of the most avidly explored areas of the earth are beneath its surface. Intrepid cavers are on a continual quest to find new caves-and when they find a new one, they map it. Mapping has multiple purposes. First, it provides a "trail map" for others, letting them know how much rope and what equipment to bring to that cave. It also provides insight into a cave's hydrology, geology, and possible additional entrances. And, on a more personal level, it delivers the satisfaction and notoriety of being the first to sketch the contours and features of a new cave.
Teenage Inspiration Becomes Adult Avocation
Growing up in West Virginia, a teenager named Mark Passerby was inspired one day when he stumbled across a Reader's Digest story about caving. Mark talked some friends into exploring some limestone caves near his home with him, and soon he was hooked on going into known caves, an activity known as "sport caving." When he became proficient at going where others had gone before him, it was a natural progression to move on to cave exploring-looking for new holes in the ground. "I wanted to explore new places, and promote caving to others," he says. On the promotion end he started a website, www.caves.com, devoted to sharing information with other cavers around the world. To fulfill his need for exploring, he started looking for new untouched ground on which to walk-and crawl, and slide, and climb.
Of course, finding new caves meant creating maps instead of following them. So Mark and his fellow cave explorers honed their mapping skills, initially using the time-worn methods. For years, cave mapping had been done entirely on paper. Explorers took measurements based on rudimentary surveying techniques and wrote them down, also hand-drawing contours and features of the cave. Once they were back above ground, they transferred the measurements and drawings to map paper and refined them.
The Old Way, the New Way, and the Search for a Better Way
The advent of computer software that could translate data into maps was helpful. Now cavers could write measurements down on paper in the cave, and then later enter the measurements into a spreadsheet and transfer that data to a program that processed it and produced a cave map. But one elemental problem remained: ensuring accuracy in the data transfer. Because the data was taken in muddy, wet, humid, and poorly lit environments, the error rate between data taken and data entered was tremendously high. Wet, muddy paper resulted in smeared ink, and handwriting done under those conditions often looked worse than a doctor's prescription. As he continued to explore new caves, Mark experienced the common thought that has motivated innovations for centuries: There has to be a better way.
So he began experimenting with entering the data onto small, handheld computers while in the caves. But his early efforts were not fruitful-the computers available were not built rugged enough to withstand the environment inside the caves. He knew that using a truly rugged handheld device would solve the problem, but that product hadn't come along yet.
Then someone sent him a note through his website about the TDS Recon, a handheld computer being used by professional surveyors, and built rugged enough to withstand just about any conditions. After some investigation into the product, Mark contacted Tripod Data Systems, asking for a Recon demo to use and review on his website. Mark explored and mapped three caves near Lewisburg, West Virginia using the Recon: "Bobcat Blowhole," "Deels Hole," and "Middle Earth." In the case of Bobcat and Deels, he was with the first team to explore the caves.
He discovered Bobcat after coming across a volleyball-sized blowhole in the ground that looked promising. (Many undiscovered caves "breathe" through small blowholes such as this; when cavers find an opening in the ground that has air moving out of it, their own breathing tends to speed up.) He and his partners-Bob Kirk, Aaron Bird, and Rachel Bosch-blasted out enough rock around the blowhole to squeeze in 10 feet, where they found that the hole opened up into a drop down to an underground creek. After mining out the creek and crawling through more tight passages, they found a larger crawlway-1,200 feet long-that ended with what he calls a "muddy, wet, and nasty" 35-foot drop into a 150-foot-by-250-foot room, 75 feet high. The cave was theirs to name, map, and tell the world about.
Tough Environment? We've Got Your Tough Environment-Right Here
And now a word about cave environments. First of all, a cave's temperature is constant; it holds steady at the average year-round temperature of the land above it-in the Lewisburg area, 52º F. What's more problematic is the humidity-in the caves Mark hangs out in, it's 100 percent, all the time. And "living" caves-those with consistent water supplies, which keep their formations and rooms growing-are, as a result, very muddy. When exploring large caves, Mark and his colleagues are underground anywhere from eight hours to three days at a time. Suffice to say it's not your typical family camping trip. And the equipment has to go wherever the caver goes-including those tiny, muddy crawlways mentioned above. Different explorers use different methods to bring along their gear; in a crawlway Mark normally straps a carry bag to his ankle and drags it along behind him. As a result, whatever is in the bag is frequently kicked and dropped, and ends up muddied and wet. This could explain why he had trouble finding a handheld that could hold up.
Surveying, Caveman Style
The process of mapping a cave usually involves a team of three to four explorers. While Mark and his fellow cavers aren't professional surveyors and their maps aren't legal documents, they follow many similar principles and procedures. Traditionally a mapping team will begin at the entrance of a known cave and mark a starting station. As they proceed into the cave, they mark a second station in the line of sight. Then they measure a distance from the first station to the second station, and take and record an azimuth and an inclination as well as estimates of the left and right wall points at each station. Traditionally, caving instruments included a tape measure, a Suunto Tandem compass/ clinometer, and a survey book for recording the data and drawing the "to scale" rough sketch. After exiting, the cavers would enter the data manually into a desktop cave surveying program that served to close loops, process data, and plot a line of the surveyed data's traverse. The sketches would then be redrawn over the actual data that was processed by the cave surveying software to arrive at a finished map.
The exploration of Bobcat Blowhole began a crucial evolution of the process of cave mapping, moving far beyond the labor-intensive traditional process previously described. The tape measure has been replaced with a DISTO laser measure. And, instead of a handheld clinometer, Mark's crew uses a digital level strapped to the DISTO to provide the inclination from station to station in the traverses. The DISTO provides the laser point, while the digital level provides the inclination reading. The biggest improvement on the traditional process, though, is using the Recon. The cavers can input the data directly into a spreadsheet on the Recon, using a preprogrammed format that matches the format of the desktop cave surveying software (Mark uses COMPASS cave surveying software and the WALLS cave survey data management tool).
With the Recon, when the crew exits the cave, all that needs to be done is a simple copy-and-paste function from the Recon to the desktop software. Instantly, all the collected data is available on the desktop for processing and loop closure. This eliminates having to enter the data twice-as well as the errors that are intrinsic to that process. Then, with the data in the desktop cave surveying software, Mark can process a lineplot that can be used to redraw the "working" sketches and orient them to actual processed data. The finished product is a complete map of the cave. Furthermore, he can overlay the lineplot onto a topo map or use it in GIS software to gain further understanding of surface features in relation to the subterranean features he's mapped.
Mark used the Recon in the three caves, which was enough to definitively prove its worth. "I'd have eight hours of data compiled, and in between entering it I'd be dragging the Recon through a 1,200-foot crawlway," he says. "Sometimes I'd have to throw my pack in front of me, and it would roll down a drop, hit a rock-things got knocked around pretty good. The Recon would take a beating for hours, and when I'd turn it on, it would work great. I didn't have to go out of my way to protect it from water and mud, which also made it different than the other handhelds I'd tried." In addition, the Recon was good for 15 hours of operating time on a single battery charge-a real plus on multi-day exploration trips. (By adding the new Recon AA PowerBoot Battery Module, he could take a small supply of AA batteries down with him and use them to power the Recon over several days.)
Perhaps the most impressive practical benefit of using the Recon to map caves was the net time savings. According to Mark, the double-entry data process he previously used-once in the cave, again to the main computer-would typically take eight hours in the cave and eight hours in the office. Entering data directly to the Recon and then cutting and pasting it to the main computer? Eight hours gathering, 10 minutes transferring.
The Challenges Just Keep on Coming
New tools like the Recon have improved the process of cave exploration tremendously from a technological aspect. But conditions in caves and the quest to find uncharted territory remain as daunting as ever. Next year Mark and the Caves.com Expedition Team are off to Georgia (the one in Russia) to assist a Russian team exploring deep caves there, including one named Voronja that is believed to be the world's deepest cave. A previous expedition into Voronja ended when the team ran out of rope and was forced to turn back after descending well more than a mile below the earth's surface. At -1,710 meters, they could hear running water below them-a good sign that the cave goes deeper. This time they'll bring more rope. And when they're more than a vertical mile down, several days into a trip spent in humidity, mud, and temperatures in the high 30s, you can bet they'll be thankful to have the Recon-new technology that helps them bring back information from a place no one's ever been.
lives in Portland, Oregon, and writes about a wide variety of technology-related subjects.
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