The focus of the project today moved to Rock Spring in Kelly Park. For previous exploits at this site see ‘Rock Springs Rocks’ and ‘Hard Rock, Soft Wings’. The aim was to reassess the site prior to taking samples for bacterial and water chemistry analysis as we have been doing so far at Wekiwa Spring. Before diving at Rock Spring, the team placed a crayfish trap at Moccasin Sink, a steep-sided sinkhole in Kelly Park not far from Rock Spring. It is clear that a lot of debris has fallen into this sinkhole during the hurricanes last year. We could see at least one troglobitic crayfish in the sinkhole as we were placing the trap, so hopefully this will yield a specimen for comparison with those from the other sites.
The dive team consisted of Terrence, Rhiannon and Andrew. Despite multiple equipment failures, we managed to accomplish some useful work. It is worth pointing out here that the flow of water from Rock Spring has increased substantially since our last visit to this cave. One reason is that the output of springs in this area is known to be at their highest at this time of year. It has also been observed that since the hurricanes the flow from many springs in Florida has increased, presumably because of increased water content in the aquifer, the layers of porous rock that hold the State’s groundwater. It was certainly more effort to make progress into the cave today than on previous occasions and at times it felt like we were swimming up a fire-hose. At about 700 feet into the cave there is a low passage (known as bedding plane) to the left, which had old guideline in it, evidence of previous exploration. It was this line that Terrence and Andrew on an earlier dive had discovered to be dangerously frayed. It was also secured only to an old geology hammer, probably because of the lack of secure tie-off points in such a high-flow area. As the passage is so small, Terrence swam ahead on his own to lay new line alongside the old. He then removed the old guideline. By this time his primary light had failed and one of Rhiannon’s regulator’s was delivering more water than air. The team therefore exited the cave.
As our regular viewers will already know, caves are formed because limestone, the type of rock in which most caves are found, is dissolved by carbonic acid. This weak acid is formed when rainwater drips through decaying organic matter on the ground. The acidic water initially follows minute cracks or faults in the limestone, and gradually enlarges one or two of these preferentially until we have a cave big enough to swim into. On the right hand side of this page is a picture of the same process at work – a solution tube formed by acidic dissolution of limestone.
After the dive in Rock Spring we returned to Moccasin Sink to check the crayfish trap. So far nothing but minnows. Watch this space.