ACKMA Newsletter No 10. December 1992. Pages 22 – 24.

Introduction

Tourist cave development in the 1990's will avoid the use of wire.  Where wire must be used, its type will be select(to minimize harmful effects on the cave environment and its location chosen so that it is effectively invisible.  In fragile parts of the caves alternative lighting and protection will be devised so that even the "invisible" wires are obsolete.

Many of the caves discovered in the nineteenth century in Australia and New Zealand and subsequently developed as tourist attractions were narrow with many fine delicate decorations.  It was soon realized that damage to these caves would easily result due to careless actions of visitors.  The desire to show these caves to the general public meant that they had to be protected in new ways and developed differently from the larger European Caves.  The Jersey Cave at Jenolan, for example, contains a 100 m section of passage less than a metre wide and two metres high decorated with many erratic speleothems.

"The formations on walls are extremely delicate, some of it is white and some like yellow coral.  The roof has been slightly defaced by certain nineteenth century cads.  In various places the "mark of the beast" in lampblack has been produced by holding candles near to the ceiling and moving them about gradually.  The sooty Heiroglyphics remain unto this day as an evidence of vanity and folly.  The floor which was once like alabaster, is now soiled by the tramping of feet." (Cook, 1889).

To answer to this need for protection, wire netting was introduced to distance people from cave decorations and minimize further damage.

Wire Netting

The premier tourist caves in Australia are NSW’s Jenolan Caves. Until the 1980s wire netting was regarded as the only protective device for masses of delicate speleothems in small passages and those that are close to the edge of pathways.

The first reference to any wire netting being placed in the caves at Jenolan comes from a letter written by Jeremiah Wilson, the first caretaker of Jenolan Caves, on the 18th of March, 1879 to the Minister for Lands: 

"will you be so kind as to have some money voted so that I can have wire screening and other protection made to keep it from being destroyed by people walking on it.  It is not my intention to take other visitors to this cave for some time till the necessary improvement is done. I believe this cave is one of the prettiest sights in the Colony".  (Harvard   1934)

As with many other innovations in developing tourist caves, Jenolan Caves pioneered the use of wire and the rest of Australia followed.  Buchan Caves in Victoria apparently received this information from Jeremiah Wilson’s brother Fred Wilson on his move there from Jenolan. Oliver Trickett, the superintendent of caves for the Department of Mines, travelled extensively around Australian, visiting caves and spreading the technology widely.  The consequences of all this was that hideous corridors of wire netting appeared throughout Australia caves whether they were needed or not and even spread across the Tasman Sea to New Zealand.

The support for the wire netting was a rough form of round or square steel uprights.  The principle method of fixing steel posts and steel supports in caves was to drill a hole of slightly larger diameter than the base of the steel post.  A cement-water mixture was then made, placed in the hole and the steel post inserted.  Bolts placed in stalagmite or bed rock were also used to fix the wires.  No. 8 fencing wire (a steel wire 3mm diameter) was strung between the posts and the netting fixed to this by smaller diameter wire.

There is little evidence to suggest that the rest of the world used netting to protect speleothems.  However, it would that other places were aware of its application and considered using it, for example Cango Caves, South Africa. The rest of the world fortunately did not accept netting but another Jenolan innovation was universally accepted - electrical wires.

Electrical Wire

In 1886, electric lighting replaced the far more damaging magnesium wire and candles as a means of lighting Jenolan Caves.  The use of candles and magnesium wire for lighting Jenolan Caves was of major concern to Jeremiah Wilson because of the resultant combustion products and he reported on the matter to his superiors at the Department of Mines.  On July 22, 1880, E. C. Cracknell temporarily illuminated the Margherita Cave with electric light.  This was the first recorded use of electricity for lighting any cave in the world and came only two years after the electric lighting of the Thames Embankment, London (Harvard 1934).

In those early days there was no attempt to hide the electrical wires; mains wires were strung from insulators attached to the cave walls and light bulbs were suspended in a similar manner.  Later, electrical wires were pinned to walls and speleothems and special groves or trenches were cut to take the wire cables.  Poorly planned cave lighting inherited from earlier times is still in place today and can be observed throughout Australian and New Zealand caves.

The Need for Improvement

In the late 1970s it became clear that at Jenolan Caves some of the most beautiful caves in the world were being displayed in an archaic manner; the protective wire netting and the electrical wires were detracting from the enjoyment of informed cave visitors.  On aesthetic grounds alone wire should be removed from the caves but there are many other reasons to remove it.

Deterioration of the netting results in foreign iron and zinc compounds being formed causing unpleasant staining of speleothems, contamination of pools and slippery areas on the pathways.  The breakdown of electrical wires that are sheathed in lead produce lead carbonate (cerussite), an unpleasant white compound, and copper wires react to form the blue and green basic copper carbonate minerals, azurite and malachite.

Wire netting collects massive accumulations of lint from the air and from visitors clothing as they brush past. It has been suggested that the netting collects the lint and prevents it accumulating on the cave decorations.  This is not what has been observed at Jenolan; the accumulated lint on the netting can be knocked onto the tracks and if it gets wet it forms a pulpy slime; whether wet or dry it will spread around the cave.

Defective netting and wire rope handrails can splinter when held or brushed against. in the past wire splinters have been removed from several hands.  The sharp pieces of wire also tear clothing.

Little is known about the impact of wires and their decomposition products on the micro-fauna in the caves.  It is suspected that the lead and copper compounds are toxic to cave fauna.

Clearly a case could be made for the removal of all wire but this is not practical.  Present cave management practices require that any wire is not intrusive in the cave scenes being viewed by the visitors. At Jenolan Caves this philosophy has meant that many of the eyesores of the past have been removed and replaced by less obvious forms of protection and lighting.

Removal of Wires

The removal of wire fixtures is not easy.  If they have deteriorated, the wires and their casings break up into small pieces requiring the surrounding cave area to be cleaned.  A use for these old wires has been found at Jenolan by encasing them in a plastic material believed not to decompose and setting them as reinforcing in concrete pathways.

The steel post bases are more difficult to remove because they have expanded on rusting to become tightly fixed in their cement beds.  A variety of methods have been tried.  When removal was attempted by the use of gas torches it was found to be very damaging because heat causes exfoliation of both the limestone and calcite.  Use of steel saws to remove the post to ground level covers the surroundings with a very fine dust and a significant amount of the fitting left in the rock to decay.  The removal of these steel fixtures is now accomplished by periodically tapping them with hammers and after a while they become loose and can be removed with little damage to the rock or speleothem.  Even though there is now a satisfactory method for their removal, steel supports can still be seen protruding from the speleothems in several Australian caves.

The removal of electrical wiring is somewhat easier, although where the fixtures have been set in cement, problems are similar to wire netting removal.  The more attractive antique electric light fittings have been left in place and are used to illustrate past technology during historical cave tours.

Replacement

Wire netting is being replaced with controlled lighting which creates a dark zone between track and decorations, that is lighting is being used for protection.  An alternative method being tried is electronic beams which when broken activate a siren.  This method is being used extensively in the tourist development of Cutta Cutta Cave, in the Northern Territory.  Some caves are small and fragile, one such cave is the Ribbon Cave at Jenolan.  In this cave unattractive metal wire netting has been removed and yet a screen is the only practical way of protecting the multitudes of helictites in its narrow, low passages.  Carbon glass has been trialed but it has two major problems; one is abrasion of the surface, the other is collecting condensation.  Both limit the clarity with which the speleothems can be viewed. For this cave, three other methods of protection are now being considered they are clear plastic netting, widely spaced plastic covered wire and heated glass.  Heated glass especially, must be studied with care so as to avoid any problems with changes to the microclimate of the cave.

At Jenolan Caves, the replacement of obsolete electric wiring has been a long term project.  When this takes place the wires can be realigned and the type of cables selected so that they do not decay.  On rewiring it is found that the length of cable laid can be reduced by the use of more powerful bulbs, and concentrating the available light on a restricted area using focussed beams and reflectors.  Features of the cave that require individual illumination can now be lit from a distance.

Despite the fact that there have been significant reductions in the length of cables laid in order to illuminate the caves, at Jenolan Caves more concealed cable than ever is being laid in the interests of public safety.  In 1988 a complete telephone system was installed to allow emergencies to be reported immediately.  Also a complete emergency lighting system ahs been installed into existing switch boards - the supplies of candles located on the tops of switch boards are no longer required.

In order to do away with the wires and associated fittings in selected areas of the caves, fibre optics have been successfully trialed.  At present the economics of this technology is competitive with mains electricity and gets cheaper by the day.

The end of the netting can be foreseen.  Protective screens are all expected to be either dark zones or electronic beams.  In contrast, it will be many years if ever before mains electrical power is superseded as the major form of lighting for caves.  In these days of space travel it is conceivable that fuel cells, long life batteries and possibly even nuclear cells can be placed in specific places in caves powering light sources.

Education and public awareness is an important way of resource protection and this approach is being considered by the management of Jenolan Caves for the future. The approach requires specifically designed educational material with emphasis on conservation and preservation.  With a well educated public the need for protective devices will be considerably reduced.

Conclusion

There is no doubt that the over-protective practice of using wire netting in the past has preserved the speleothems and enabled decisions regarding their future protection and management minus the wire.  The use of electric lighting, however aesthetically unappealing its placement, has allowed many thousands of visitors to appreciate the beauty of the caves and their decorations.  Jenolan Caves have been shown commercially for over 100 years and it is hoped that the caves will be displayed for thousands of years to come.  Decisions made today aye critical as an ill informed one could lead to the destruction of part of our heritage.  So away with the wire only if the alternative is fool proof.

References

Havard, W.L. (1934) The Romance of Jenolan Caves. J. Proc.  Royal Austr.  Hist.  Soc. 20 (1), 20-65.

Cook, S. (1889) The Jenolan Caves: An Excursion In Australian Wonderland. Pub. Eyre and Spottiswoode, Her Majesty’s Printers, London. 39, 18-7 1.

Dunkley, JR. (1986) Jenolan Caves; as they were in the nineteenth century. Pub. The Speleological Research Council Ltd. for the Jenolan Caves Historical and Preservation Society.