Cave Tracing Using Novel Geochemical Techniques

Following on from the Rave Sites Project (see Pelobates No 67), attention has now turned to the application of novel geochemical methods for tracing the existence of cave systems, and a number of possible methods have been evaluated.

Gamma Ray Spectroscopy

Following recent revelations that significant quantities of Radon gas can lurk in caves, an obvious method was to look for surface concentrations being flushed out by hidden but drafting cave entrances. However, what was required was a "radon sniffer", better known as a gamma ray spectrograph, and the last one I played with took up most of a large American aircraft - not the sort of thing that one wants to lug around Pant Mawr. Things have however moved on since then, and much more compact systems are now available using microchip circuits. Unfortunately, these were all found to cost in excess of £1500, considerably more than our limited budget of £1.20. Undaunted, we have however been able to construct one ex-skip for the sum of 40p (for the full yoghurt pot required for the sensor). This has proved remarkably sensitive in practice, but has not been successful at locating cave entrances due to large quantities of Radon being emitted from the significant lead/silver ore veins in the area. In fact we now suspect that the excavations carried out a number of years ago in the Hole 18 area were really a lead/silver mine!

Water Tracing Methods

Conventional tracing methods such as dyes, spores and salt have long been carried out in the Ystradfellte area. These are however both tedious and expensive, and involve the placing of artificial contaminants in the water courses, so we decided to investigate the "naturally" occuning sources of contamination. A brainstorming session came up with the following possible sources:


all of which are commonly spread over the land by the local environmentally aware farming community.

The first of these seemed to be the most promising, as during the winter a large number of shakeholes and cave entrances become the grave yard of sheep that have run out of things to eat. The challenge was to devise a method of detecting and characterising "essence of dead sheep" at low concentrations. For a while this baffled us. However, whilst wandering the moors one day, we realised that the principal beneficiary of sheep carnage was the increasing population of carrion birds, who have obviously evolved amazingly efficient methods of sniffing out death. Bird brains therefore appeared to be the answer! Although most people thought that they knew someone that would fit that description, we needed to evaluate the real thing. After futile attempts to entice the canion crows into the cottage with rancid sausages, I recollected that we had a whole department at work trying to automate the characterisation of gas odourants. They had devised a very sophisticated portable "nose" that could "remember" specific organic compound combinations, and were keen to develop alternative uses for this technology (such as looking for buried murder victims), so I have arranged to borrow the device in the spring when the sheep carnage is at its peak. Another possibility that has been suggested is that the DNA from fragments of rotting flesh extracted from resurgences is analysed and traced back to the originating farms.

Other Methods

Recently, while removing rubbish blocking a cave entrance in Church Sink, a mostly empty canister of hoof oil was found, marked with the skull and cross bones, and with the warning "do not dispose of in waterways" all over it. However, this warning was pointless as it assumed the user could read! Fortunately the canister was intact, otherwise its contents would have been sufficient to enable the risings of the Mellte river to have been traced by the bodies of dead trout!

Geochemical Correspondent