By Charlie Self
This issue of Cave and Karst Science has the usual eclectic mixture of papers on a range of topics from around the world. The Forum section contains abstracts from the 23rd Cave Science Symposium, held at the University of Leeds in March 2012.
In recent years, a number of papers have been written to explain the development of rock pedestals beneath glacial erratic boulders in limestone terrains. This latest contribution suggests that snow-related processes could have been an important factor during periods of deteriorating climate. In such conditions, wind scour concentrates both mechanical and dissolution processes in a ring around obstacles such as erratic boulders. In a useful "discussion" section, the highly variable nature of our climate since the ice retreated 18,000 years ago is explained. The authors acknowledge that dissolution during temperate periods may also contribute to surface lowering, with or without the presence of soil, as suggested by two rival theories. Their conclusion that pedestal formation is not the result of a single process means that the rate of surface lowering is never constant and therefore should no longer be expressed in the form "millimetres per thousand years".
Believe it or not, this cave history paper is fun to read. In 1931, a young South African visited Carlsbad Caverns on his way home after graduating from an American University. Arriving home in Cape Town short of funds, he wrote a satirical article about his visit to the cave which he then sent to the Cape Times. It is dour yet brilliant, totally disrespecting his host nation …… but, shock, horror, it appeared on the leader page of the newspaper with a lurid (and totally irrelevant) title. End of story …… or not quite.
Go back to the Editorial of this issue of C&KS and you will find that John Gunn has devoted a whole paragraph to an appreciation of the cave as it is now. Well done the editors: it is best not to risk offending anyone, even with a 70 year old reprint!
This paper gives a summary of all eleven species of this cute-looking lizard that have been reported from the caves and karst of Thailand. Colour photographs complement descriptions of the animals and their known distribution. The geckos appear to be using the caves for shelter, going outside at night to feed. The majority of species have a very restricted geographical range and this isolation of gecko populations may be responsible for the evolution of so many species.
This is part of an ongoing study of phreatic network caves in the Northern Pennines. Four groups of caves are known, three of them accessed via old lead mines. The most extensive of these is found in Devil's Hole Mine in Swaledale, where almost 6 km of natural passages have now been recorded. Some of these passages were modified by the miners to enable them to install railway lines for their ore tubs.
These network caves are mostly of horizontal passages formed at the top of the Main Limestone sequence (of the Yoredale Group, which lies above the Great Scar Limestone). With no evidence to suggest a direction of water flow, it is thought that the caves were fed by diffuse discharge from more permeable beds that lie above (and also below) the Main Limestone. A number of passages have blind terminations, characteristic of diffuse discharge mazes. In one part of Devil's Hole Mine, there are natural vertical shafts going down towards the base of the Main Limestone; their presence may be related to a shallow syncline in the rocks of this part of the mine.
The Main Limestone extends beneath a large area of the Northern Pennines. Many similar maze caves must be present, though access may only be possible through old mine workings.
The importance of this botanical study is that it was made in the entrance zone of a cave in volcanic rocks, rather than in limestone karst where most such studies have been conducted. The 29 taxa (plant types) found include cyanobacteria (blue-green algae), green algae, diatoms (also algae), bryophytes (mosses and liverworts), a fern species and five types of lichen. This is broadly similar to the flora of limestone cave thresholds, though some differences are apparent. This is probably due to the high latitude of this Icelandic cave, where air temperature and humidity are more significant than light availability or rock type.