After doing a short dive at The Boils, a large spring coming through road fill in Jackson County, TN, a local caver, Amanda Pigg asked if Anne Elmore and I would like to take a look at another nearby Jackson County Spring. We hadn’t heard of anything else in Jackson county, but the dive gear was already wet, so why not? Amanda proceeded to race down backcountry roads across Jackson County, eventually stopping near a bridge across the Blackburn River where we got out of the vehicles and she strapped her young boy Kaven (pronounced like “cabin” with a “v”) into his kiddie backpack for a little walk. Though there was not really obvious evidence of a spring head here, she announced that it was a short walk and we would have to bushwack through the high grasses and weeds. A pleasant 200 feet later we all stood on a low bank overlooking a 20 foot wide spring pool with two visible spring vents- one about a foot in diameter close to the western edge of the pool, and a second one, a low ledge about four feet underwater that appeared to have some small rocks laying up against it, under a bright green blanket of filamentous algae. The first entrance was obviously too small, I could stand on the edge of it and see that it was dropping down about two feet deep, but then had a rocky floor where it narrowed into a fissure. The lower entrance looked more interesting. I thought that there might be a chance to move some of the rocks and possibly make a passable entrance.
Not one for moving tanks a long distance through the woods, we backed the vehicle up a little closer to the spring and unloaded the sump diving tanks and gear into the water. The sump gear is a little different than normal cave diving gear- it requires much smaller tanks, in this case steel 50 cubic foot tanks, which are worn along the side of the body. There is no buoyancy compensator, or jacket- only the drysuit can be used to add additional buoyancy. And finally the weight belt. Not just a belt around the waist, but a whole harness with weight distributed across the shoulders as well, which takes the place of the attachment points normally found on a buoyancy compensator. Of course the usual complement of three light sources, and a reel of cave diving line, for finding your way back out, should the visibility drop to zero. And last, but not least, the underwater survey book for documenting anything that might be found.
Once in the water, I started moving rocks. A lot of rocks. It was difficult to tell if rocks had been stacked in front of the entrance intentionally, which I suspect might be the case, or if they just happened to be there. Regardless, after twenty minutes of moving rocks out of the way, the lower entrance was starting to look passable. The opening had cleared up to expose a narrow bedding plane slot, about 8 inches high and 30 inches wide. I don’t really like going head first into something this small, on the off chance that a piece of gear might get hung, and you would be stuck head down in a very small hole, so I slipped my fins backward into the slot. I had seen that there was a larger space just beyond the bedding plane squeeze, but it was difficult to see how large it was. I wriggled my fins back into the cave, then my knees, and my thighs, but stuck at my hips. Small pieces of cobble, which made up the shallow slope leading into the cave were getting wedged between my hip bones and the bedrock bedding plane. After shoveling some more of the cobble, and trying to reduce the angle of the slope in front of the entrance, I was able to get my hips and waist through the bedding plane. This was going really well! I finally wriggled back far enough for my chest to start into the crevice where I stopped fast. My inflator on my drysuit added just enough thickness that I couldn’t back any further into the bedding plane. I pulled myself out of the cave a foot or so, and dug some more on the little cobbles- hoping that I could clear a path for my drysuit inflator. After another five minutes of gravel shaping, I tried again to back down into the narrow slot, and with a little exhalation, popped through the narrowest spot.
This was my first proper view of the cave, and as I swung my large cave diving light around, I was amazed to see a decent sized passage heading off to the west. It’s hard to say if everything looks bigger and feels happier after squeezing through such a tight place, but I was certainly enjoying the size of the passage, about four and a half feet wide and five feet tall. The water was crystal clear, fading off to deep blue in the distance, and each little piece of tan limestone on the floor was coated with a filigree of fine chert. The floor was a nicely scalloped small gravel interspersed with hand sized chert nodues, indicating that the cave had periods of high flow, but today, it was lazily moving water past me. I began a slow swim down the passage, unwinding my diving line behind me, occasionally wrapping it around small protrusions along the floor, making a solid pathway for me on the way out. The depth was slowly increasing, from four feet at the entrance working its way deeper. This is always a good sign, as most underwater spring caves do not stay shallow in Tennessee, though I had never been in one in Jackson County. As I continued down the passage, I came to a place, after about 200 feet, I came to the first split in the passage. I tie my line around a small bulge on the right side, and decided to try the right passage first. It looked smaller, but it was also solid rock on both sides, instead of silty. Less chance that I would make a mess of the visibility, should I have to turn right around. I squeezed between the chert ledges on the walls, turning sideways to fit between the narrow spots, and was able to progress about a body length before the cave would no longer allow me to pass. I was able to see that it appeared that the passage might end, or at least drop into a very small hand sized passage along the floor, from which the water was issuing. I backed out, reeling up my line, and returned to my last tie off. Looking left, I took a long look at the second passage. It was quite a bit wider- almost 12 feet, but lower- it looked as if a slab of the ceiling had fallen, and the passage continued over the slab, but very low, and there was a deep layer of fine silt on top of the breakdown.
Some decisions had to be made. I could likely get through the passage over the breakdown, and it appeared that it might drop down again after about 15 feet on the other side of the breakdown slab, but I would definitely reduce the visibility to zero, as I would have to slide through that silt layer on top. Also, the presence of the silt layer also meant that this area had lower flow normally, which doesn’t usually mean there will be more passage on the other side. It was possible that most of the flow normally came through the narrow passage on the right. In addition, as this was my second dive of the day, my tanks were only half full at the start of the dive, leaving me much less gas to deal with any contingencies, even though I had not yet reached the first third of my gas allowed for the dive. (Cave divers use 1/3 of their gas for entry, 1/3 of their gas for exit, and leave 1/3 for emergencies.) Knowing that coming out of the restriction at the entrance might be more difficult than coming in also weighed on my mind. With enough things on the against tally, I made a final tie off of my diving line, and added a line arrow with my name on it, to indicate the exit direction, and dug out my survey book.
With the cave as explored as it was going to get for the day, it was time to “do the hard part” as Gerald Moni would say, and collect the data. In a few short minutes, I was back at the entrance of the cave, looking out at the narrow restriction, with the light streaming into the cave, and a myriad of small, very colorful fish swimming about. I took some time to look at the fish, as I had never seen that many colors of fish outside of freshwater pools in Mexico, it looked as if someone had dumped their freshwater fish tanks full of cichlids in the spring. The fish were plenty friendly, and very interested in my light, as they swam about my mask and bumped their noses into the bright light. Soon it was time to start on the squeeze to get out of the cave. I anticipated it being tight, but as I got my chest started into the restriction, I was getting hung up. The ledge that made the bedding plane and vertical portion on the inside of the cave that was hanging my gear, where it had not done so going the other direction. I tried a bit more, exhaling, wriggling, and every time, the blocks of weight on my harness would catch on the narrow ledge. I inched back into the cave to see what might be the problem. I shoveled a little more cobble through the bedding plane into the cave, and tried that, but still the same issue. I could get just far enough to get my face out of the cave, but no further. Finally I decided that though my tanks were not thicker than my body, the right side of the crevice was slightly larger, and by getting closer to that side, I might be able to squeeze through. I removed my right tank, and swung it forward out of the cave, holding onto the valve so it would not escape from me. I slid a couple inches to the right, and with a little exhale, and a lot of shoving against the slope of cobble, was able to inch my way out to my hips, where I finally broke free of the narrow bedding plane.
The fish were sad to see me go, as they quickly scattered back towards the entrance while I slowly swam my way to the edge of the pool, to let everyone know about the discovery. The final data indicated 205 feet of passage, with a max depth of 23 feet, generally trending north under the Blackburn River. So far, the deepest and longest underwater cave in Jackson County, though a far cry from either of those milestones in Tennessee as a whole.