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BRIAN'S RAVINE DIG By Bill Walker Photos by Sean's Camera Wednesday night (June 11), Brian Williams took Sean and me to a dig in a remote section of Marion County. Brian found the dig a few years ago, and brought the Vinzants and Sean there last weekend. They worked all day on the blowing lead and were stopped by a large block of extremely hard chert with going crawling passage below. The block would need the type of persuasion that Sean and I were familiar with. Sean and I drove to the dig site and found Brian's truck parked on the side of the road. Sean had told me that the dig was located at the end of a ravine in the woods. We walked into the lush hardwood canopy and instantly disappeared from the site of the road. We walked down into the biggest ravine I'd ever seen in Florida! The ravine was 40' deep and between 150'-200' across to the other side. The bottom was a dry, wet weather stream bed. We walked about 500' downstream to the head of the ravine. Ravines in Florida karst are formed by some sort of collapse and are sculpted by the sink taking on water from larger and larger areas. When you walk down into a Florida karst ravine they abruptly end. This is a good place to dig, especially if there is exposed limestone at the bottom. The ravine we were in takes the overflow from a huge swamp and is the biggest water sucking monster that I've ever seen! It was formed in the side of a 200' high ridge and the swamp is at about 110' above sea level. The head of the gully is at about 90' above sea level, and this is the contact where the Hawthorne Formation (clay) meets the Ocala Limestone. The ridges in the area are huge Hawthorne capped ridges, very similar to the area around Warren Cave in Gainesville. We may have the same thing going on here as at Warrens (the longest mapped cave in Florida). At Warrens, the Hawthorne Formation acts as a confining unit and directs the formation of the cave at the contact.  Bill and Brian in the Ravine Brian had arrived a little earlier and was waiting at the dig with an air tank and some tools. We got to work on the piece of chert that blocked the way. This was some hard stuff with lots of silica. We started drilling and the bit started to glow molten orange! We then tried with an electric hammer drill and this fared no better. Our next plan was to use a little persuasion on the limestone rock opposite the chert. We ran into a few snags because our equipment wasn't working. By this time, Brian was totally frustrated. "I'm just going to wail on that damn chert until it yields!" Sean held Brian's railroad tie mover while Brian pounded on it with a short handled 10 pound sledge. After about fifteen minutes of hammering, Brian removed enough rock to slip in. He left for about ten minutes and then returned. He reported back that the passage was a 6 foot long squeeze through breakdown. The passage took a hard right and opened up into a little room and then continued on down a crack. But, "it's scary as hell down there. I want you to go look at it Bill." I squeezed down into the breakdown and contorted my body around the hard right corner. The little room I popped into was about 5 feet high and ten feet long. The scary part about this "room" was that it was developed in a conglomerate of limestone and clay. This was the transitional layer between the Hawthorne and the limestone, and the entire room (walls, floor, and ceiling) was composed of cantaloupe sized, white-washed limestone cemented together with grey, tacky clay. The room had been formed by water rushing through this layer and hollowing it out – lot's of water, and it looked like the whole thing could come down at any second. Beyond this area, the cave dropped down further and I could see down a solid limestone fissure crack. This is where the bedrock actually started. But to get into the crack would mean ducking under this highly unstable wall. Nope, not today. I carefully climbed out of this room and back into the breakdown squeeze (trying not to touch anything!) On my way out, I noticed that the big chert rock that we had worked on (the one which I was now on my back looking up at), was only held up by a fist sized rock. Sean checked it out next and on his way out of the squeeze, his foot dislodged a large rock. I just happened to snap a picture of him while this happened – priceless. We all decided that the cave was too dangerous to continue on, and we don't know exactly what to do. The safest plan might be to dig straight down from the surface into the room. There is about ten feet of dirt and rock above it, so it might not be a monumental task. Hopefully we won't get distracted by another dig and abandon this one. The potential for big cave here is just too good. Captions 1. Bill looking down at the hole. 2. Brian with his new air drill. 3. Sean working on the triangular piece of chert that gave us so many problems. 4. Brain giving up the modern techniques and wailing on the rock with a long chisel and 10 pound sledge. 5. Sean in the hole the second the passage started collapsing in around him. Notice the look of fear on his face. 6. Sean posing once he realizes that he's not going to die. (Also, check out that 60 LED light on his head!)
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