Laclede County, MO
(Underwater Photos by Tami Thomsen)
Ethan Brodsky collects data at survey station 12 in Morgan Big Spring.
BackgroundSeveral years ago, while running canoe trips down the Osage Fork of the Gasconade River, Micki Feakes brought along her SCUBA gear to look at a small spring she had noticed. To her surprise, the small spring, known locally as Wabiwakema, gave way to a hidden cave system. It was apparent that a diver had been there before, but after asking around, nobody knew who had conducted the initial exploration and no map was available. On her initial trip to the spring, she noticed some interesting isopods (small white critters) living on the ceiling. She discussed her find with a cave biologist from the Natural History Division of the Missouri Department of Conservation, and he requested that she collect some samples of the lifeforms for further investigation. Her finds are believed to be a unique specimen of Caecidotea and were recorded in the Missouri Biospeleogical Database. With several new members to our group, we had been looking for a small cave in which to practice survey techniques and develop an effective methodology to apply to our larger ongoing projects. As Micki believed Morgan Big Spring to be about 200-300 feet in length, we thought it would be a good choice, especially considering its shallow depth and biological significance.
PreparationIt was decided that the survey would be conducted over five phases. First was to install a knotted survey line in the cave and set up stations. Second was to take Depth/Azimuth/Distance readings at each station. Third, we made a computer-generated preliminary map to guide our further data collection. Fourth, we measured passage geometry at each station, drawing cross-sections at certain selected points. The fifth (not yet completed) phase, is to create a detailed map for publication.
On the way out of Madison, we made several stops to pick up supplies. Midland Plastics supplied the bulk plastic sheet for our survey slates, and Recreational Equipment Incorporated provided Brunton survey compasses. Just before getting out of town, we realized we had forgotten the jig-saw to cut the slates, so we had to run back to the shop and pick it up. After a ten hour drive to Falcon, Missouri, we immediately set to work making our slates. Here Tami lays out a grid for data collection, while Ethan works on the laptop outlining procedures for the survey (actually I'm looking at pictures from a recent trip to Florida).
LogisticsMorgan Big Spring abuts private property about half a mile upstream of where Atlanta Road crosses the Osage Fork and is easily reachable by watercraft. After loading our gear from the bridge, we launched our canoe, heavily laden with three sidemount divers and their equipment, and paddled up to the spring. At one point, we had to get out and belay the canoe through a section of rapids.
We used a sandbar near the spring as our staging area to suit up and prepare for the dive. After a final briefing, we swam across the river to start our dive. We did a quick photo shoot in the cavern before we began laying our survey line.
Micki Feakes enters Morgan Big Spring, followed by Ethan Brodsky.
CartographyWe crunched the data each night on Tami's laptop. This achieved several objectives: it guaranteed that the data would be archived in case a slate was lost on later dives (it could happen to anyone, and I found it anyway, it only took twenty minutes!); it gave us a reality check, making apparent any major errors; and it gave us a preliminary map so that divers had a better working understanding of the cave. We used data from multiple divers on the same section of cave to verify the accuracy of our survey.
Below is one of our preliminary maps, showing what we can produce shortly after getting out of the water. We are in the process of applying all of the cross sectional data and detailed drawings to generate a final map for publication and archival. While it is fairly easy to generate a quick line drawing from raw data, making an asthetically pleasing map that gives an accurate understanding of the cave is both an art and a science. It takes a great of skill and practice to create the maps you see published in cave diving journals.
Data and Basic Plan-View Stick Map