Gers, C. (1998). Diversity of energy fluxes and interactions betweenarthropod communities from soil to cave. Acta Oecologica, 19,205�213.

Juberthie, C. (2000). The diversity of the karstic and pseudokarstichypogean habitats in the world. In H. Wilkens, D. C. Culver &W. F. Humphreys (Eds.), Subterranean ecosystems (pp. 17�39).Amsterdam: Elsevier.

Kogovsek, J. (1990). The properties of the precipitations seepingthrough the Taborska Jama roof. Acta Carsologica, 19, 143–156.

Pipan, T. (2005). Epikarst—A promising habitat. Postojna�Ljubljana:ZRC Publishing at Karst Research Institute ZRC-SAZU.

Pipan, T., Lopez, Oromı., P., Polak, S., & Culver, D. C. (2011).Temperature variation and the presence of troglobionts in terres-trial shallow subterranean habitats. Journal of Natural History 45,253�273.

Simon, K. S., Pipan., T., & Culver, D. C. (2007). A conceptual modelof the flow and distribution of organic carbon in caves. Journal ofCave and Karst Studies, 69, 279�284.

SHOW CAVESArrigo A. Cigna

Union Internationale de Speleologie

A SHORT HISTORY OF SHOW CAVES

Caves have always attracted the attention of humanssince prehistory, but at that time the interest was mainlyquite practical, that is, to have a shelter, a sanctuary,or a burial place. Later, until the Middle Ages, caveswere associated with the devil or hell in general andpeople feared going into them. For this reason, banditscould use caves as hiding places without problemsfrom undesired visitors.

Some historical show caves were known already inancient times. About 2000 year ago Plinius, a Romanwriter, described the “Dog’s Cave” near Naples, Italy,being visited by people because of the peculiar releaseof carbon dioxide close to the floor which killed smallanimals (hence its name) while standing people werenot affected. Other caves were visited not purely fortourism but mainly for religious purposes: suchshrines may be found everywhere.

In Postojna Cave (Slovenia), on the walls of theso-called Passage of the Ancient Names were foundold signatures left by occasional visitors, the mostancient ones dating back to 1213, 1323, and 1393 accord-ing to some authors of the nineteenth century. Around1920, such signatures were scarcely visible on accountof the seepage; presently the oldest signature which canbe read easily dates 1412 and from the sixteenth centuryonward they became rather abundant. This means thatfrom the sixteenth century the cave was visited morefrequently by many persons attracted by the under-ground world. Therefore, this period may be consideredthe start of cave tourism.

In a more recent time the Cave of Antiparos in Cyclades,Greece, became a great attraction in the seventeenthcentury as documented by the many prints reproducingthe cave. The Kungur Cave, 100 km SE of Perm, nearKungur (Urals), Russia, is an ice show cave already vis-ited in the eighteenth century. Probably it is the largestshow cave in gypsum. On August 13, 1772, the scientistJoseph Banks landed on Staffa Island and in Novemberhe wrote in the Scots Magazine: “. . . there is a cave in thisisland which the natives call the Cave of Fingal.” Sincethat time this cave became one of the best known cavesof the world, inspiring poets and musicians. Its famewas so great that it became the natural cave most repre-sented in paintings and engravings all over the world.

The Cango Cave (Oudtshoorn, South Africa) wasdiscovered around 1780 and the first recorded visitwas made in 1806. A few years later, a farmer boughtthe land around the cave with the exclusion of theentrance. The Governor included into the deeds thecondition that the farmer was obliged to leave, per-fectly free and undisturbed, the entrance of the cave,to be considered as public property, with a road in hisland to reach the cave. This document has a historicalimportance because it is probably the first attempt inthe world to legislate for cave protection.

In the United States, the Mammoth Cave, Kentucky,was defined “the stellar attraction of the MammothCave National Park” by Gurnee and Gurnee (1990).Already known in prehistory, in the late eighteenthcentury the cave was mined for saltpeter to make gun-powder. But only at the beginning of the followingcentury, Mammoth Cave became a tourist attraction.

If a show cave is defined as a cave where a fee ispaid in order to have access and to visit it, then the old-est one is the Vilenica Cave in Slovenia. The cave isclose to the village of Sezana, just a few kilometers fromthe Italian border. At the beginning of the seventeenthcentury, the Count of Petac began to invite the peopleof Trieste and some noble friends to visit the cave. Oncertain holidays, a hundred meters from the entrance,an area for the orchestra and a dance floor were set upand the entire dripstone passage was illuminated withtorches and candles. Probably already in 1633, theCount Benvenut Petac charged admission to visit thecave. Part of the money was donated to the local churchof Lokev where masses were dedicated to “greatersafety” of the people in the cave.

THE ENVIRONMENTAL PROTECTIONOF SHOW CAVES

A cave is an environment with little contact withthe outside. For this reason its equilibrium may be eas-ily changed when additional energy is introduced

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(Cigna, 1993). Obviously, such changes may occurmore frequently when the whole energy budget of thecave is small, but in case of show caves the energybudget is often not very small, because of their sizewhich is generally large. A river or a subterranean lakeplays an important role in keeping the natural equilib-rium because they may absorb any further input ofenergy more easily than rock.

In a show cave both the visitors and the electriclighting system release energy into the environment.A person who is walking releases nearly as muchenergy as a 200-W bulb at a temperature of about37�C. Therefore, the total energy released by hundredsor thousands of visitors in a day is not negligible as anabsolute amount. The heat released by the electriclighting system has the same order of magnitude.

There are different ways to keep the additionalenergy input into the cave as low as possible. Alimit of the number of visitors is given by the so-calledvisitors’ capacity, which is defined as the maximumnumber of visitors acceptable in a time unit underdefined conditions which does not imply a permanentmodification of a relevant parameter. Otherwise,instead of reducing the number of persons, the timethey spend in the cave may be reduced. This resultmay be easily achieved when people enter the cavethrough one entrance and exit along another passage,instead of returning along the same pathway wherethey got in.

Using high-efficiency lamps can reduce the contri-bution by the electric lighting system. A further reduc-tion can be obtained if the lamps are switched on onlywhen visitors are in the vicinity.

Another perturbation of the cave environment isthe lint (hair, dry-flaking skin, dust from shoes, andlint from clothing) left by visitors. In caves visitedby a large number of people, the accumulation of lintbecomes a real problem to be solved by an accurateremoval. In fact, such lint would cause deterioration offormations and reduce their pristine white beauty to ablackened mess.

Lint released into a cave might be reduced by meansof air curtains at the entrance. Such a solution wouldwash people entering the cave and, at the same time,isolate the cave environment from outside since an aircurtain acts as an invisible door and prevents airflowthrough it.

The protection of the environment of a showcave is fundamental both from the point of view ofavoiding any damage to a nonrenewable patrimonyand the conservation of the source of income forthe cave management. Therefore, such a commoninterest may have an important role in the imple-mentation of any action aiming to safeguard the caveenvironment.

Visitors also release carbon dioxide as a result oftheir breathing. Until few years ago, such carbon diox-ide was considered a threat to the cave formationssince it could have increased the water acidity and,consequently, the corrosion instead of the depositionof new formations. Further accurate studies (Bourgeset al., 1998) have shown that in many instances the car-bon dioxide produced by natural processes (oxidationof organic matter in the soil above a cave) may intro-duce through the water percolating into the caveamounts very much larger than the carbon dioxidereleased by visitors.

When the water, with a relatively high concentra-tion of carbon dioxide, reaches the cave environmentit releases immediately part of such carbon dioxide,which is not in equilibrium with the carbon dioxidein air. Therefore, the chemical reaction moves towardthe deposition of calcium carbonate and the forma-tions continue to grow. In general, rather small caveswith a high visitor flux and without any input of nat-ural carbon dioxide might have formations corrodedbecause the chemical reactions would be reversedwhen the carbon dioxide of air dissolves into water,particularly when water vapor condenses on the cavewalls.

Another form of environmental pollution may occurthrough a joint contribution by visitors and light.Persons release into the cave spores or seeds of plantsand they may grow in the vicinity of lamps if the lightflux is high enough. The result is the so-called lampen-flora, that is, green plants (generally algae, fern, moss)developing on cave walls or formations close to alight source. Such plants cover the surfaces with agreenish layer, which can become included into thecalcite deposition and no longer removable. In fact, thelampenflora may be washed away by bleach or hydro-gen peroxide if it is not covered by any calcite. Specialcare must be taken to avoid any nuisance to the cavefauna.

The growth of lampenflora can be avoided by em-ploying light sources with a very low emission of lightuseful for the chlorophyllian process and low lightflux at the rock surface.

THE DEVELOPMENT OF A SHOW CAVE

A correct development of a show cave must takeinto account both the protection of the environmentand the safety of the visitors. As it has been alreadypointed out in the previous paragraph, the physicaland chemical equilibria of the environment should bemodified outside the range of the natural variations.

At the same time, any undue source of harm to thevisitors must be avoided. This means that the

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pathways must be strong enough to withstand thevery high humidity and, sometimes, also floods. In thepast, wooden structures were often used, but they hadto be replaced frequently; currently, some “green” peo-ple would still use wood because this material is natu-ral. Nevertheless, the rather short life of a woodenstructure in the cave environment implies an addi-tional cost which is not justified by any advantage. Onthe contrary, the rotten wood supplies large amountsof food modifying the equilibrium of the cave life.

In particular at present, the criterion to use onlystructures which can be easily decommissioned is sub-stantially wrong because once it is no longer conve-nient to manage a show cave, no one will spend moneyto take out structures inside the cave. Only when showcave managers will be obliged to deposit a givenamount of money to assure the future decommission-ing of any structure, it is possible to use structures tobe easily disassembled.

In the meanwhile, it is preferable to use materialswhich are compatible with the cave environment andwill not release pollutants in the long run. A materialwith these characteristics and not expensive is con-crete. It may be conveniently used for pathways ingeneral.

The handrails in stainless steel are also a convenientsolution, particularly when they are also used as pipesto provide water in different parts of the cave to washout the pathways. In fact, a higher cost of stainlesssteel is justified by a lack of any maintenance aftermany years of operation. Sometimes plastic may beused under the condition that it does not contain anycontaminant (e.g., heavy metals or organic compoundswhich may be released).

When an artificial entrance is needed in order togive an easy access to the cave or to establish a circuitby avoiding the return of visitors on the same path-way, it is absolutely necessary to install a system ofdoors to stop any additional airflow in the cave. Upuntil now, doors operated mechanically or manuallyare normally used, but it would be most preferableto install air curtains. This solution (suggested manyyears ago by Russell Gurnee and Jeanne Gurnee) isless expensive, quite safe, and has the great advantageof avoiding any sense of claustrophobia to visitors.In addition, it also decreases the release of lint bypeople as reported previously.

The surveillance of the main parameters (tempera-ture, humidity, carbon dioxide, radon, etc.) can beachieved by a monitoring network, which shouldalways be installed in any show cave. Presently, it ispossible to install networks at a very reasonable cost,which are reliable and require little care, as, forinstance, data loggers, which can be discharged everymonth, and the data transferred into a computer for

any further evaluation. Automatic networks directlyconnected to a computer are operated more easily but,of course, their cost is higher. In any case, it must bestressed that any kind of monitoring network alwaysrequires some attention to avoid malfunctioning andcalibration, possibly once a year.

Such monitoring networks have also another impor-tant advantage because they contribute much interest-ing data, which have greatly enlarged the knowledge ofthe behavior of cave environment. A rather widespreadfeeling among speleologists, and people in general, thata cave is lost to science when it is developed as a touristattraction is not at all supported by the importantscientific results obtained just within many show caves.Sometimes the borderline between use and abuse maybe difficult to define; nevertheless, a careful develop-ment continuously monitored may be the most efficientway to protect a cave.

It is evident that the economy of a region around ashow-cave-to-be can be radically modified by the cavedevelopment. Therefore, strenuous opposition to anytourist visitation appears to be rather unfair also towardthe local people, particularly when a suitable compro-mise between strict conservation and a sound develop-ment can be found. But in any case, as it was previouslyreported, cave development cannot be accepted if it isnot supported by appropriate preliminary research.

An evaluation of the number of show cave visitorsall around the world (Cigna and Burri, 2000), basedon data obtained for about 20% of all show cavesindicated a number of more than 150 million visitorsglobally per year. By assuming a budget per person asreported in Table 1, the total amount of money spentto visit the show caves is around US$ 2.3 billion. Thenumber of the local people directly involved in theshow cave business (management and local services)can be estimated to be several hundred per cave, thatis, some hundreds of thousands of individuals in theworld.

By taking into account that there are several hundredother people working indirectly to each person directlyconnected with a show cave (Forti and Cigna, 1989), a

TABLE 1 Rough Estimation of the Annual Direct and LocalBudget of a Show Cave per Visitor (2008 US$)

Direct income 6.5

Other local income:

Souvenirs & snacks 2.0

Meals 6.5

Transportation 2.5

Travel agency 2.5

Total 20.0

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gross global figure of about 100 million people receivesalaries from the show cave business. Therefore, it canbe roughly assumed that behind each tourist in a showcave there is about one employee directly or indirectlyconnected.

In addition to show caves, the existence of karstparks, which include a cave within their boundaries,must also be considered. As reported by Halliday(1981), the number of visitors of three top karstnational parks in the United States (Mammoth Cave,Carlsbad Caverns, and Wind Cave) amounted to about2500,000 tourists each year. Therefore, karst parks givea further increase to the number of people involved inthe whole “karst” business.

There are many other human activities whichinvolve a larger number of people; nevertheless, thefigure reported above is not negligible and gives anindication of the role that show caves play in theglobal economy.

GUIDELINES FOR THE DEVELOPMENTOF SHOW CAVES

Some guidelines aiming to supply a recommendation tobe endorsed for the development of show caves weredrafted over the past few years and received strongrecommendations from the UIS Department of Protectionand Management at both the 14th International Congressof Speleology held in Kalamos, Greece, in August 2005and the 15th International Congress of Speleology heldin Kerrville, TX, in July 2009. These guidelines are herereported.

1. Development of a Wild Cave into a Show Cave

The development of a show cave can be seen as a positivefinancial benefit to not only itself but also the area sur-rounding the cave. The pursuit of these antici-pated benefitscan sometimes cause pressure to be applied to hasten thedevelopment of the cave. Before a proposal to develop a wildcave into a show cave becomes a physical project, it is neces-sary to carry out a careful and detailed study to evaluate thebenefits and risks, by taking into account all perti-nent fac-tors such as the access, the synergy, and possible conflictwith other tourism-related activities in the surroundingarea, the availability of funds, and many other related fac-tors. The conversion should only take place if the results ofthe studies are positive. A wild cave that is developed into ashow cave, and is subsequently abandoned, will inevitablybecome unprotected and be subject to vandalism in a veryshort time. A well-managed show cave assures the protectionof the cave itself, is a source of income for the local economy,and may also contribute to a number of scientific researches.

1-1 A careful study of the suitability of the cave fordevelopment, taking into account all factors influenc-ing it, must be carried out, and must be carefully eval-uated, before physical development work commences.

2. Access and Pathways within the Cave

In many caves it has been found to be desirable to provide aneasier access into the cave for visitors through a tunnel, or anew entrance, excavated into the cave. But such an artificialentrance could change the air circulation in the cave, causinga disruption of the ecosystem. To avoid this, an air lockshould be installed in any new entrance into a cave. On theother hand, it must be mentioned that in some very excep-tional cases a change in the air circulation could revitalizethe growth of formations. A decision not to install an airlock must be taken only after a special study.

2-1 Any new access into a cave must be fitted with anefficient air lock system, such as a double set ofdoors, to avoid creating changes in the air circulationwithin the cave.

Caves are natural databases, wherein an incredible amountof information about the characteristics of the environment,and the climate of the cave, are stored. Therefore, any inter-vention in the cave must be carried out with great care toavoid the destruction of these natural databases.

2-2 Any development work carried out inside thecave should avoid disturbing the structure, thedeposits, and the formations of the cave as much aspossible.

When a wild cave is developed into a show cave, pathwaysand other features must be installed. This invariablyrequires materials to be brought into the cave. These materi-als should have the least possible impact on both the aes-thetics of the cave and its underground environment.Concrete is generally the closest substance to the rock thatthe cave is formed in, but once concrete is cast it isextremely expensive and difficult to modify or decommis-sion. Stainless steel has the distinct advantage that it lastsfor a long time and requires little to no maintenance but itis expensive and requires special techniques to assemble andinstall. Some recently developed plastic materials have theadvantage of a very long life, are easy to install, and are rel-atively easy to modify.

2-3 Only materials that are compatible with the cave,and have the least impact on the cave, should beused in a cave. Cement, concrete, stainless steel, andplastics are examples of such materials.

The environment of a cave is usually isolated from the out-side and therefore the introduction of energy from the outsidewill change the equilibrium balance of the cave. Such changes

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can be caused by the release of heat from the lighting systemand the visitors and also by the decay of organic materialbrought into the cave, which introduces other substances intothe food chain of the cave ecosystem. In ice caves, the envi-ronmental characteristics are compatible with wood, which isfrequently used for the construction of pathways, as it is notslippery.

2-4 Organic material, such as wood, should never beused in a cave unless it is an ice cave where, if neces-sary, it can be used for pathways.

3. Lighting

The energy balance of a cave should not be modified beyondits natural variations. Electric lighting releases both lightand heat inside the cave. Therefore, high-efficiency lamps arepreferred. Discharge lamps are efficient, as most of theenergy is transformed into light, but only cold cathodelamps can be frequently switched on and off without incon-venience. Lightemitting diode (LED) lighting is also verypromising. As far as possible, the electric network of a caveshould be divided into zones to enable only the parts thatvisitors are in to be lit. Where possible a noninterruptiblepower supply should be provided to avoid problems for thevisitors in the event of a failure of an external power supply.

3-1 Electric lighting should be provided in safe, well-balanced networks. The power supply should prefer-ably be noninterruptible.

It is essential to ensure the safety of the visitors in the cave,particularly in the event of a failure of the main power sup-ply. Emergency lighting should always be available whetherit is a complete noninterruptible power supply or an emer-gency lighting system with an independent power supply.Local code requirements may be applicable and these maypermit battery lamps or a network of LEDs or similardevices.

3-2 Adequate emergency lighting should be availablein the event of a power outage.

Lampenflora is a fairly common consequence of the introduc-tion of an artificial light supply into a cave. Many kinds ofalgae, and other superior plants, may develop as a result ofthe introduction of artificial light. An important method toavoid the growth of green plant life is to use lamps that donot release a light spectrum that can be absorbed bychlorophylll.

3-3 Lighting should have an emission spectrum withthe lowest contribution to the absorption spectrum ofchlorophyll (around 440 nm and around 650 nm).

Another way to prevent the growth of lampenflora isthe reduction of the energy reaching any surface where the

plants may live. The safe distance between the lamp and thecave surface depends on the intensity of the lamp. As arough indication, a distance of one meter should be safe.Special care should also be taken to avoid heating the forma-tions and any rock paintings that may exist.

3-4 Lighting sources should be installed at a distancefrom any component of the cave to prevent thegrowth of lampenflora and damage to the formationsand any rock paintings.

The lighting system should be installed in such a way thatlights only in the portions of the cave occupied by visitorsare switched on, leaving the lighting in the portions of thecave that are not occupied switched off. This is importantfrom the aspects of reducing the heating of the cave environ-ment and preventing the growth of lampenflora, as well asdecreasing the amount of energy required and its financialcost.

3-5 Lighting should be installed in a manner toenable only the portions of the cave that are occupiedby visitors to be illuminated.

4. Frequency of Visits and Number of Visitors

The energy balance of a cave environment can be modifiedby the release of heat by visitors. A human being, moving ina cave, releases about 150 W— approximately the same asa good incandescent lamp. Consequently, there is also alimit on the number of visitors that can be brought into acave without causing an irreversible effect on the climate ofthe cave.

4-1 A cave visitor capacity, per a defined time period,should be determined and this capacity should not beexceeded. Visitor capacity is defined as the number ofvisitors to a given cave over a given time period, whichdoes not permanently change the environmental para-meters beyond their natural fluctuation range. A con-tinuous tour, utilizing an entrance and another exit,can reduce the time that visitors spend in a cave, com-pared to the use of a single entrance/exit.

In addition to the normal tours for visitors, many showcaves have special activities, sometimes called adventuretours, where visitors are provided with speleological equip-ment for use in wild sections of the cave. If such a practiceis not properly planned, it may cause serious damage to thecave.

4-2 When visits to wild parts of a cave are arranged,they must be carefully planned. In addition to pro-viding the participants with the necessary speleologi-cal safety equipment, there must be experiencedguides to show the wild caves. The pathway thatvisitors travel along, must be clearly defined, for

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example, with red and white tape, and the visitorsshould not be allowed to walk beyond this pathway.Special care must be taken to avoid any damage tothe cave environment, and the parts beyond the path-way must be maintained in a clean condition.

5. Preservation of the Surface Ecosystem WhenDeveloping Buildings, Parking, Removal ofSurface Vegetation, and Waste Recovery

It is important that the siting of the aboveground facilities,such as the buildings, parking, and waste recovery, be wellplanned. There is a natural tendency to try to place thesedevelopment features as close as possible to the caveentrance. Sometimes these features are built over the caveitself, or relevant parts of it. The hydrogeology above thecave must not be modified by any intervention such asthe watertight surface of a parking area. Any change in therainwater seepage into a cave can have a negative influenceon the cave and the growth of its formations. Care should beexercised also when making any change to the land abovethe cave, including the removal of the vegetation and distur-bance of the soils above the bedrock.

5-1 Any siting of buildings, parking areas, and anyother intervention directly above the cave must beavoided in order to keep the natural seepage of rain-water from the surface in its original condition.

6. Monitoring

After the environmental impact evaluation of the develop-ment, including any other study of the cave environment, itis necessary to monitor the relevant parameters to ensurethat there is no deviation outside acceptable limits. Showcaves should maintain a monitoring network of the caveenvironment to ensure that it remains within acceptablelimits.

6-1 Monitoring of the cave climate should be under-taken. The air temperature, carbon dioxide, humidity,radon (if its concentration is close to or above thelevel prescribed by the law), and water temperature(if applicable) should be monitored. Airflow in andout of the cave could also be monitored.

When selecting scientists to undertake studies in a cave, it isvery important that only scientists who have good experi-ence with cave environments be engaged for cave-relatedmatters. Many otherwise competent scientists may not befully aware of cave environments. If incorrect advice is givento the cave management, then this could result in endanger-ment of the cave environment. Cave science is a highly spe-cialized field.

6-2 Specialized cave scientists should be consultedwhen there is a situation that warrants research in acave.

7. Cave Managers

The managers of a show cave must never forget that thecave itself is “the golden goose” and that it must be pre-served with great care. It is necessary that persons involvedin the management of a show cave receive a suitable educa-tion, not only in the economic management of a show cave,but also about the environmental issues concerning the pro-tection of the environment at large.

7-1 Cave managers should be competent in both themanagement of the economics of the show cave andits environmental protection.

8. Training of the Guides

The guides in a show cave have a very important role, asthey are the “connection” between the cave and the visitor.Unfortunately, in many instances the guides have not beentrained properly and, notwithstanding that they are doingtheir best, the overall result will not be very good. It is veryimportant that the guides receive proper instructions aboutthe environmental aspects of the cave as well as dealing withthe public. It is important that guides are skilled in tactfullyavoiding entering into discussions that can have a detrimen-tal effect on the overall tour. The guides are the guardians ofthe cave and they must be ready to stop any misbehavior bythe visitors that could endanger the cave environment.

8-1 Cave guides should be trained to correctly informthe visitors about the cave and its environment.

INFORMATION ON SHOW CAVESIN THE WORLD

There are many books published in different coun-tries providing guides to the local caves. On one handthey report a rather large amount of information but,on the other hand, they are fully reliable only fora short time after their publication. Information onvisitor details and even the existence of the show cavescan change frequently.

Recently, a rather useful way to obtain up-to-dateinformation became available. “Showcaves of theWorld” is a website (Duckeck, 2000) that can be foundat www.showcaves.com/. This site changes and growscontinually, so the latest version may always be seenon the web Figures 1�7.

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FIGURE 2 Kartchner Caverns (AZ, U.S.A.). Sometime in a cavethere are joints which may imply possible rock fall. In order to assurethe safest condition in a show cave, it is necessary to detect well inadvance any minor movement. A detector, monitoring possible dis-placement of a limestone layer, can be seen in this photo. Photographtaken by the author.

FIGURE 1 Kartchner Caverns (AZ, U.S.A.) are probably the showcaves in the world, managed according to the most up-to-date crite-ria. An electric train from the office building to the cave is availablefor visitors, avoiding both acoustic and environmental pollution.Photograph taken by the author.

FIGURE 3 Kartchner Caverns (Arizona). A monitoring networkshould always be envisaged in a show cave in order to avoid relevantchanges of the cave environment. In the case of Kartchner Caverns,such monitoring is particularly important since the relative humiditywithin the cave is close to 100%, while outside the climate is very dry.During the construction of a pathway, many pipes are placed to becovered by concrete. Such pipes are used for circuits connecting anysensor within the cave with a computer in the main building for pres-ent and future monitoring networks. Photograph taken by the author.

FIGURE 4 Cango Caves (Oudtshoorn, South Africa) was discov-ered around 1780 and the first recorded visit was made in 1806; nowit is the most important show cave of Africa. Here a flowstonedeposited over a clay filling, which has been washed away succes-sively, can be seen. Iron handrails along the pathway in the forefront:Nowadays such handrails are generally substituted by stainless steelor plastic handrails, to avoid iron contamination of the cave environ-ment. Photograph taken by the author.

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See Also the Following Articles

LampenfloraRecreational Caving

Bibliography

Bourges, F., D’Hults, D., & Mangin, A. (1998). Etude de l’Avend’Orgnac. Rapport final, Laboratoire Souterrain de Moulis C.N.R.S. Geologie Environnement Conseil, pp. 1�84.

Cigna, A. A. (1993). Environmental management of tourist caves.Environmental Geology, 21, 173�180.

Cigna, A. A., & Burri, E. (2000). Development, management andeconomy of show caves. International Journal of Speleology, 29B(1�4), 1�27.

Duckeck, J. (2000). Showcaves of the world. ,www.showcaves.com/..Forti, P. & Cigna, A.A. (1989) Cave tourism in Italy: an overview.

Proceedings of the International Symposium on the 170thAnniversary of Postojnska Jama. Postojna, Nov. 10-12, 1988,Centre for Scientific Research SAZU & Postojnska Jama Touristand Hotel Organization, p. 46�53.

Gurnee, R., & Gurnee, J. (1990). Gurnee guide to American Caves.Closter, NJ: R. H. Gurnee Inc.

Halliday, W.R. (1981) Karstic national parks: International economicand cultural significance. Proceedings of the InternationalSymposium on Utilization of Karst Areas, Trieste, March 29�30,1980, Commissione Grotte Boegan, CAI Trieste, pp. 135�144.

FIGURE 5 Cango Caves (Oudtshoorn, South Africa). In one of theinnermost parts of the cave, Cango 3, which is not open to tourism,the floor is covered by calcite crystals; a plastic ribbon fixes theboundaries of the trail, to avoid any destruction of the crystals due toscientists moving around. Photograph taken by the author.

FIGURE 6 Hwanseon Cave (Daei, South Korea) is a very impor-tant show cave of Korea. Tourists reach the vicinity of the cave bycar or bus and then they have to climb a slope of a couple of kilo-meters to reach the cave entrance, which is here depicted. Photographtaken by the author.

FIGURE 7 Frasassi Caves (Ancona, Italy) developed mainly inthe shallow phreatic zone, where rising hydrogen sulfide�richgroundwater mixes with oxygenated seepage water. Presently, theseare the most important show caves in Italy. Details may be foundin www.frasassi.com. Shown here is Niagara Falls. Photo courtesyof Ente Consorzio Frasassi.

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