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Folia are speleothems that resemble bells, inverted cups, or bracket fungi, and whose origins are still controversial. Cenote Zapote (an underwater cave) in the Yucatán Peninsula (México), is home to some of the largest folia reported to date. These speleothems are currently growing in an active underwater system, meaning this site offers an excellent opportunity to constrain the different formation models proposed for folia, which have traditionally relied on inactive examples. In Cenote Zapote, folia are closely related to bubble trails and cupolas, suggesting an underwater CO2-degassing process. In thin section, they display a succession of columnar-open and columnar-elongated endings in micrite-dendritic fabrics. Our petrographic and geochemical results demonstrate the abiotic origin of these folia and indicate carbonate precipitation from cold water by CO2 degassing below the water table that started at least 5,210 yrs BP. We conclude that these folia formed as a result of subaqueous calcite precipitation around CO2 bubbles trapped below overhanging walls of the cave. The sequential alternation of columnar and micritic fabrics can be explained by changes in the position of the halocline and H2S-rich water mass while the exceptional size is the result of carbonate precipitation from waters saturated in CaCO3 during thousans of years. Then we propose the classification of these speleothems as a subtype of folia. This subtype could be named Hells Bells, respecting its original description.

15 páginas.- 5 figuras.- 85 referencias.- The following are available online at http://www.mdpi.com/2079-6412/10/11/1134/s1 .- This article belongs to the Special Issue Biofilms on Cultural Heritage, The Galapagos Islands (Ecuador) have a unique ecosystem on Earth due to their outstanding biodiversity and geological features. This also extends to their subterranean heritage, such as volcanic caves, with plenty of secondary mineral deposits, including coralloid-type speleothems and moonmilk deposits. In this study, the bacterial communities associated with speleothems from two lava tubes of Santa Cruz Island were investigated. Field emission scanning electron microscopy (FESEM) was carried out for the morphological characterization and detection of microbial features associated with moonmilk and coralloid speleothems from Bellavista and Royal Palm Caves. Microbial cells, especially filamentous bacteria in close association with extracellular polymeric substances (EPS), were abundant in both types of speleothems. Furthermore, reticulated filaments and Actinobacteria-like cells were observed by FESEM. The analysis of 16S rDNA revealed the presence of different bacterial phylotypes, many of them associated with the carbon, nitrogen, iron and sulfur cycles, and some others with pollutants. This study gives insights into subsurface microbial diversity of the Galapagos Islands and further shows the interest of the conservation of these subterranean geoheritage sites used as show caves, This research was funded by the Ecuadorian Ministry of Environment (Project PC-65-14 National Park Galapagos), by the Spanish project MINECO CGL2016-75590-P with European Regional Development Fund and the Portuguese Foundation for Science and Technology (Fundação para a Ciência e a Tecnologia-FCT) under the project UID/Multi/04449/2019 for HERCULES/UE. AMGS was supported by a FPU fellowship of the Spanish Ministry of Education, Culture and Sport (AP2010-2052). AZM was supported by a Marie Curie Intra-European Fellowship of the European Commission’s 7th Framework Programme (PIEF-GA-2012-328689-DECAVE) and a CEECIND/01147/2017 contract from FCT. MLC was supported by a CEECIND/00349/2017 contract from FCT. FG was financially supported by the “HIPATIA” research program of the University of Almeria.

24 páginas.- 14 figuras.- 5 tablas.- 136 referencias.- Supplementary data to this article can be found online athttps://doi.org/10.1016/j.scitotenv.2020.141218, The migration of geogenic gases in continental areas with geothermal activity and active faults is an important process releasing greenhouse gases (GHG) to the lower troposphere. In this respect, caves in hypogenic environments are natural laboratories to study the compositional evolution of deep-endogenous fluids through the Critical Zone. Vapour Cave (Alhama, Murcia, Spain) is a hypogenic cave formed by the upwelling of hydrothermal CO2-rich fluids. Anomalous concentrations of N2O and NO2 were registered in the cave's subterranean atmosphere, averaging ten and five times the typical atmospheric backgrounds, respectively. We characterised the thermal conditions, gaseous compositions, sediments, and microbial communities at different depths in the cave. We did so to understand the relation between N-cycling microbial groups and the production and transformation of nitrogenous gases, as well as their coupled evolution with CO2 and CH4 during their migration through the Critical Zone to the lower troposphere. Our results showed an evident vertical stratification of selected microbial groups (Archaea and Bacteria) depending on the environmental parameters, including O2, temperature, and GHG concentration. Both the N2O isotope ratios and the predicted ecological functions of bacterial and archaeal communities suggest that N2O and NO2 emissions mainly depend on the nitrification by ammonia-oxidising microorganisms. Denitrification and abiotic reactions of the reactive intermediates NH2OH, NO, and NO2− are also plausible according to the results of the phylogenetic analyses of the microbial communities. Nitrite-dependent anaerobic methane oxidation by denitrifying methanotrophs of the NC10 phylum was also identified as a post-genetic process during migration of this gas to the surface. To the best of our knowledge, our report provides, for the first time, evidence of a niche densely populated by Micrarchaeia, which represents more than 50% of the total archaeal abundance. This raises many questions on the metabolic behaviour of this and other archaeal phyla. © 2020 Elsevier B.V., This work was supported by the Spanish Ministry of Economy and Competitiveness through projects PID2019-110603RB-I00 , CGL2016-78318-C2-1R and CGL2016-78318-C2-2R AEI/FEDER/UE, and with the scientific and technical contribution of the following projects: CGL2016-75590-P with ERDF funds, CGL2017-83931-C3-2-P and CGL2017-87216-C4-1-R , AEI / FEDER , UE. S. Cuezva was funded by the European Union's Horizon 2020 - Research and Innovation Framework Programme under the Marie Skłodowska-Curie grant agreement No 844535 — MIFLUKE. N. Otero was funded by the Serra Húnter Fellowship ( Generalitat de Catalunya , Spain). We thank to GERA-group of the Fire-fighters Service of Madrid Autonomous Region for the essential work on installing the system of tubes for air sampling and the Council of “Alhama de Murcia” for their technical assistance during fieldwork.

9 páginas.-- 3 figuras.-- 2 tablas.-- 83 referencias.-- Selected paper from the XVI Latin-American Congress on Chromatography (XVICOLACRO) and the 9th National Meeting on Chromatography (9ENC), 5–9 January 2016, Lisbon, Portugal., This study comprises an innovative approach based on the combination of chromatography (analytical pyrolysis and pyrolysis compound-specific isotope analysis (Py-CSIA)), light stable isotopes, microscopy and mineralogy analyses to characterize the internal layering of coralloid speleothems from the Ana Heva lava tube in Easter Island (Chile). This multidisciplinary proxy showed that the speleothems consist of banded siliceous materials of low crystallinity with different mineralogical compositions and a significant contribution of organic carbon. Opal-A constitutes the outermost grey layer of the coralloids, whereas calcite and amorphous Mg hydrate silicate are the major components of the inner whitish and honey-brown layers, respectively. The differences found in the mineralogical, elemental, molecular and isotopic composition of these distinct coloured layers are related to environmental changes during speleothem development. Stable isotopes and analytical pyrolysis suggested alterations in the water regime, pointing to wetter conditions during the formation of the Ca-rich layer and a possible increase in the amount of water dripping into the cave. The trend observed for δN values suggested an increase in the average temperature over time, which is consistent with the so-called climate warming during the Holocene. The pyrolysis compound-specific isotope analysis of each speleothem layer showed a similar trend with the bulk δC values pointing to the appropriateness of direct Py-CSIA in paleoenvironmental studies. The δC values for n-alkanes reinforced the occurrence of a drastic environmental change, indicating that the outermost Opal layer was developed under drier and more arid environmental conditions., A.Z. Miller acknowledges the support from the Marie Curie Intra-European Fellowship of the European Commission’s 7th Framework Programme (PIEF-GA-2012-328689). The Spanish Ministry of Economy and Competitiveness (MINECO, project CGL2013-41674-P) and the FEDER Funds are acknowledged for the financial support. N.T. Jiménez-Morillo thanks the MINECO for funding his pre-doctoral FPI fellowship (BES-2013-062573).

Use of δ11B provides a solid tool for discriminating hydrogeochemical processes in complex coastal aquifers. Its efficiency increases markedly when it is applied along with other major or minor constituents. Nevertheless, various factors may affect its interpretation: the presence of clays, which favour adsorption and desorption, the influence of wastewaters, and even the presence of geothermalism. The δ11B has been applied to the study of a series of aquifers in south-eastern Spain: Castell de Ferro (Granada), Campo de Dalías, Lower Andarax and Sorbas (Almería), all of which are complex and heterogeneous. The results obtained demonstrate that the concentration of Br, the SO4/Cl and Cl/Br ratios are good indicators of marine intrusion. Inland some negative values of δ11B (−16.7 and −8.1‰) are related to a geothermal influence (34.8 and 51.5°C). The boron solubility is directly related to temperature favours boron mobilization, even from the associated metapelitic deposits. The difference in the boron isotope content in two carbonate units must be caused by the different composition of the carbonate rocks, as well as a long residence time.

This article highlights the relationship between speleothems growing inside gypsum caves and the particular climate that existed during their development. Speleothems in gypsum caves normally consist of calcium carbonate (calcite) or calcium sulphate (gypsum) and the abundance of such deposits greatly differs from zone to zone. Observations carried out over the last 20 years in gypsum caves subjected to very different climates (Italy, Spain, New Mexico, northern Russia, Cuba, Argentina) highlight wide variation in their cave deposits. In arid or semi-arid climates, the speleothems are mainly composed of gypsum, whilst in temperate, humid or tropical regions, carbonate formations are largely predominant. In polar zones no speleothems develop. These mineralogical details could be useful paleoclimatic indicators of climate change. The interpretation proposed is based on the fact that in gypsum karst the kind of speleothems deposited is determined by competition between the two principal mechanisms that cause precipitation of calcite and gypsum. These mechanisms are completely different: calcite speleothem evolution is mainly controlled by CO2 diffusion, while gypsum deposits develop mostly due to evaporation. Therefore, the prevalence of one kind of speleothem over the other, and the relationship between the solution–precipitation processes of calcite and gypsum, may provide evidence of a specific paleoclimate. Additionally, other non-common deposits in gypsum caves like moonmilk, cave rafts and dolomite speleothems can be used as markers for the prevalence of long, dry periods in humid areas, seasonal changes in climate, or rainfall trends in some gypsum areas. Moreover, the dating of gypsum speleothems could contribute paleoclimatic data relating to dry periods when calcite speleothems are not deposited. In contrast, the dating of calcite speleothems in gypsum caves could identify former wet periods in arid zones.

In Spain, evaporite outcrops cover approximately 7% of the total area of the country. Most of the evaporitic formations are made up of Ca-sulfates (gypsum/anhydrite) or Ca-sulfates and halite. Certain Paleogene marine evaporites also contain K-Mg-chlorides, and some Tertiary continental formations bear substantial amounts of Na-sulfates in the subsurface (glauberite and thenardite). Mesozoic evaporitic formations commonly wedge out towards the ground surface, passing into condensed sequences and dissolution-collapse breccias. Some of these highly porous breccias constitute major regional aquifers. In several areas, interstratal karstification of the evaporites has given rise to gravitational deformations such as basin structures, monoclines, and collapse structures covering several square kilometers that record a cumulative subsidence in excess of 200 m (Teruel and Calatayud Grabens). A widespread consequence of evaporite dissolution processes in Spain is the hydrochemical degradation of surface waters. Some of the largest and most outstanding lake systems, from an environmental perspective, occur in karstic depressions developed in evaporitic formations (Fuente de Piedra, Gallocanta, Bujaraloz, and Banolas lakes). Sinkhole activity is a major geohazard in several evaporite karst areas. The sinkhole risk has a particularly high impact in sectors where Tertiary evaporites are overlain by Quaternary alluvial aquifers (Calatayud, Zaragoza, and Madrid areas). Some of the detrimental effects of subsidence include severe damage to historical monuments (Calatayud), the demolition of a whole village (Puilatos), or the derailment of a freight train (Zaragoza area). The deepest gypsum caves are found in Triassic diapiric structures (El Sumidor Cave, 210 m deep), and the longest ones are developed in horizontally lying Neogene sequences (Sorbas caves, and Estremera maze cave). The Cardona diapir hosts salt caves up to 4,300 m long whose genesis is related to flooding of mine galleries caused by the interception of a phreatic conduit. The main anthropogenic impacts on the endokarstic systems are related to the disposal of wastewaters and the destruction of caves by quarrying. The fluvial valleys that cross Tertiary evaporitic outcrops commonly show peculiar geological characteristics related to dissolution-induced synsedimentary subsidence phenomena: (1) Thickened alluvium filling dissolution basins up to several tens of kilometers long and more than 100 m deep. The largest thickenings are found in areas where the bedrock contains halite and glauberite. (2) Superimposed alluvial units locally bounded by angular unconformities. (3) Abundant deformational structures and paleosinkholes related to the rockhead and/or interstratal karstification of the substratum. These fluvial valleys typically are flanked by a prominent gypsum escarpment. Rock-falls favored by the dissolutional enlargement of joints derived from these scarps are the type of mass movement which has caused the highest number of casualties in Spain.

We recorded the air temperature and carbon dioxide concentration within the Cueva del Agua, a cave in Spain, under natural conditions prior to the cave being opened to tourists. Geostatistical tools are useful techniques for characterizing microclimate parameters with the aim of adopting measures to ensure the conservation and sound environmental management of tourist caves. We modelled the spatial distribution of these microclimatic parameters over an annual cycle using iterative residual kriging, revealing the stratification of air related to the cave's topography. Replenishment of the cave air is activated by convective circulation that accompanies the development of inversions in the thermal gradient of the air. Comparison of the spatial distribution of each microclimatic parameter over time enables us to characterize the exchange of air between the cave interior and the outside, as well as identify potential areas that could be opened to tourists and determine suitable visiting schedules.

The giant Geode of Pulpi (Almeria, Spain) can be considered as one of the most significant recent mineralogical discoveries in terms of geological heritage. Any tourist exploitation of this mining environment should be sustainable, and the first step is to determine the feasibility of opening the interior of the geode to visitors. To achieve this objective it was necessary to characterize the variation of physical parameters of the air and rock (gypsum crystals) during monitored visits, similar to the hypothetical visits that would occur if the geode were opened to the public. The main environmental impact of a continuous presence of people inside the geode is condensation on the surface of the gypsum crystals as a result of increased temperature and water vapor caused by respiration. The phenomenon of condensation on the gypsum crystals begins to occur with visits of two or three people for longer than 10 min. Condensation on the crystal surface brought about by this human presence could lead to the corrosion of the crystals. The total recovery time required after a visit of this type to resume the initial natural thermal and humidity conditions was 27 h. The results obtained from the environmental monitoring of the geode suggest that it is not feasible to allow visits inside it because of the mechanical impact of the visitors on the crystals and of the risk of condensation of water vapor. Copyright © 2005 Royal Meteorological Society.

Cave temperature monitoring was carried out in the Cueva del Agua de Iznalloz, Granada, Spain, a cave that has great tourist potential and which has been maintained under natural conditions for over 30 years. The cave temperature under natural conditions was used to identify possible anthropogenic influences, in order to distinguish these from the variations directly related to natural changes. In particular, the relative influence of external weather conditions, thermal modification caused by visitors and the subsequent thermal recovery of the cave were identified. In addition, controlled experiments investigated the effect of two large-scale visits (980 and 2088 visitors day−1) to the cave interior, before any tourist activities in the cave were undertaken. Correlation and spectral analyses of time series were used to determine the thermal behaviour of the cave over time. The effect of both mass visits on the air temperature in the interior of the cave was very rapid (2.5 min). The maximum perturbation of air temperature within the cave during the two experiments was after 30 and 70 min. The memory effect for temperature whilst the cave was open to the public was estimated to be 5–6 h, whilst the response to external meteorological changes exceeded one week. A permanent visitor capacity of 53 people ensures that the natural cave temperature can be regained within 4–5 h. The cave can only support small groups of visitors, not the massive visits characteristic of show caves.

The gypsum karst of Sorbas is developed within Messinian gypsum characterized by an interbedded sequence of selenitic gypsum beds and marls. This geological configuration has led to the development of an interstratal karst in which galleries have developed in the marl levels, but not in the gypsum ones. Up to six cave passage levels have been detected in the gypsum caves following stratification planes between the impervious intercalated marls and the pervious gypsum strata. The explanation for this lies in the hydrogeological history of the area. Initially, the gypsum karst evolved as a multi-layer, semi-confined aquifer under phreatic conditions, enabling the formation of small proto-conduits in the individual gypsum beds, while the intervening marls and clays acted as impervious barriers. During a second stage, after lowering of the piezometric level, vadose conditions were established in which mechanical erosion processes in the intercalated marls and clays became predominant. This genetic duality means that the gypsum karst at Sorbas can be taken as an example of interstratal karstification where the contemporary underground erosion processes and those of karstic evolution should be considered products of the hydrogeological development. The total lowering of the piezometric level during the Quaternary is at least of 120 m in the centre of the basin. Interstratal vadose caves more than 120 m below the surface possess phreatic proto-channels in their upper levels which identify the past phreatic conditions in the genesis of the caves.

Fluid inclusions and stable isotopes of giant transparent gypsum crystals in a huge geode recently discovered in Pulpi (SE Spain) are useful tools for explaining its geological formation. Fluid inclusions suggest a mixture of fluids, starting with freshwater and including seawater in more advanced stages of the gypsum crystal growth. The isotopic composition of the hydration water in the gypsum crystals agrees with a meteoric fluid. The gypsum is enriched in 34 S, which denotes genetic links with marine sulphates via freshwater dissolution-recrystallization of earlier marine evaporites.

Relatively high concentrations of NO3 usually have their origin in processes of organic pollution and excessive use of inorganic fertilizers. In the case of agricultural areas, these activities may generate great quantities of nitrates. This fact has enabled us to use the nitrate ion to characterize an exploited aquifer unit of a very complex aquifer system, as is the case for the Campo de Dalias aquifer system (SE Spain). The shallow boreholes, which draw water from intensively cultivated superficial formations, yield waters with a high NO3 content. When the boreholes are deeper and penetrate low-permeability formations in the superficial layers, the waters contain little NO3; similar to what happens in areas of recharge where agricultural activities are absent. In addition, using longitudinal sections, it is possible to demonstrate the possible existence of connections between superficial and deep aquifers using NO3 as a tracer. Similarly one can locate those sectors responsible for contamination caused by the poorly lined boreholes themselves, when they perforate more than one aquifer in a multiple aquifer formation.

In the Triassic evaporite deposits of the Betic Cordillera, halokinesis has played a fundamental role in the morphodynamic evolution of gypsum karst, as evidenced by the morphology and distribution of dolines and poljes, by data obtained from caves, and from the types of water associated with evaporite domes. Distribution patterns of major exokarstic forms display a subcircular array with collapse sinkholes located in the centre of the domes and solution drawdown dolines on the outer limits of the diapiric forms. In addition, the least mineralized waters are situated in association with the caprock gypsum; hypersaline waters, which are also hotter, drain deeper flow systems that flow out at the edges of the halokinetic structures. The morphodynamic and hydrogeological information constitute a valuable tool for the correct interpretation of the tectonic structure of such complex areas.

Tumuli are hollow subcircular domes of the most superficial stratum of gypsum, principally found in outcrops of macrocrystalline gypsum. They vary from a few centimetres to several metres in diameter and reach maximum heights of a little more than 1 m. The relationships between the morphostatistical parameters that define these formations are: h = r/3 and e = r/9, where h is the elevation of the raised layer, e its thickness and r the mean radius. Their genesis has caused some controversy over the involvement of phenomena such as hydration of anhydrite, or tectonic processes capable of explaining this folding. This paper shows their genesis linked to the dissolution of macrocrystalline gypsum and reprecipitation of microcrystalline gypsum within the same gypsiferous layer. It has been calculated that to reach the theoretical saturation within the few centimetres' thickness of the cap of the tumulus, water infiltration velocities are required of between 0·002 cm s−1 for an uplifted stratum of 2 cm thickness, and 0·03 cm s−1 for 30 cm thickness. These velocities imply the existence of very slow rates of infiltration and/or capillary movement of water within the gypsiferous layer. The secondary microcrystalline gypsum is precipitated in the intercrystalline and intracrystalline voids of the gypsum crystals, producing an increase in porosity and associated volume that causes the doming of the gypsiferous layer. The development of tumuli is a cyclic process which is favoured by a sequence of short wet and dry intervals which, in turn, facilitate the almost simultaneous processes of dissolution and precipitation. These conditions predominate in arid and semiarid climates where intense evaporation can occur suddenly following sporadic infiltration. Copyright © 1999 John Wiley & Sons, Ltd.

In the Lower Andarax river basin 3 aquifer units have been defined, namely the Carbonate Aquifer, the Deep Aquifer and the Detrital Aquifer, which between them contain a wide variety of water types. Identification of hydrogeochemical processes has been performed by studying a series of ionic ratios, comprising the principal constituents together with B and Li (Cl vs SO4, Cl vs Mg, Cl vs Li, B vs Li). Among the processes detected, the circulation of groundwaters with high concentrations of SO4 was found to have significant effects. Moreover, in the coastal region, naturally occurring processes related to the flushing of saline waters from sediments of marine origin occur in conjunction with others, clearly of human origin, that are related to saltwater intrusion. A further factor is the entry, from overlying deposits, of waters with a high saline content; this salinity is related to the flushing of sediments of marine origin. The use of B and Li together enables waters in which salinity is related to seawater to be distinguished from others in which salinity is related to evaporitic layers or to thermal areas. The concentration of Li is directly related to water temperature, while that of B is greater in the most saline sectors, of gypsiferous and/or seawater origin.

11 páginas.-- 8 figuras.-- 1 tabla.-- 33 referencias, Coralloid-type speleothems were recorded on the ceiling of the Ana Heva lava tube in Easter Island (Chile). These speleothems were morphologically, geochemically and mineralogically characterized using a wide variety of microscopy and analytical techniques. They consist dominantly of amorphous Mg silicate and opal-A. Field emission scanning electron microscopy revealed a variety of filamentous and bacillary bacteria on the surface of the Ana Heva coralloid speleothems, including silicified filamentous microorganisms. Among them, intriguing reticulated filaments resemble those filaments documented earlier in limestone caves and lava tubes. The identification of silicified microorganisms on the coralloid speleothems from the Ana Heva lava tube suggests a possible role of these microorganisms in silica deposition. © 2014 Copyright Taylor and Francis Group, LLC., This research was partially financed by Portuguese Funds through FCT- Fundaçao para a Ciencia e a Tecnologia (PEst-OE/CTE/UI0098/2011) and also by the Spanish Ministry of Science and Innovation (Project CGL2011–2569). This work was supported by FCT grant to AZM (SFRH/BPD/63836/2009).

The gypsum karst of Sorbas is developed in selenitic Messinnian gypsum, the sequence being about 120 meters in depth. Within an outcrop of only 12 km2 there is a great variety of karstic forms, among which the high density of dolines and cavities (over 1000 identified to date) is a notable feature. There also exist many and varied karren landforms, interstratification forms, and tumuli. The karren landforms are strongly developed and are of diverse types. There are also examples of microkarren and nanokarren, such as exfoliation karren or dissolved vacuoles determined by the texture and gypsum crystalline orientation. Some of these forms are unique to gypsum materials and have been described for the first time in this area. The interstratal erosion karst is very well developed due to the marly intercalations existing in the gypsum deposits. This circumstance determined the speleogenesis of the area, with the formation of galleries following the stratification planes. With this structure, the gypsum strata are little altered, and erosion of the marly strata occurs. In some zones, there is an erosive interstratification karst. The tumuli are hollow subcircular domes of the most superficial layer of the gypsum, with sizes varying from a few centimeters to several meters in diameter. Their origin is determined by processes of intercrystalline solution and precipitation, together with the capillary movement of the interstitial water in the gypsum stratum. Their development is related to the abrupt changes in temperature and humidity that are characteristic of semidesert zones such as Sorbas.

Air temperature in several galleries of the Covadura System (Sorbas Gypsum Karst, Almeria) was measured at monthly intervals over a period of 1 year. The spatial temperature distribution for each month was modeled in a geostatistical framework. The mean trend of the air temperature and the difference between each experimental temperature measurement and this trend were calculated over space and time. Both the trend and residual component were characterized using a geostatistical space–time model. A large spatial trend of the air temperature was found due to the orientation of galleries within the cave system and as a function of the distance from the main cave entrance. Kriging was used for the spatial estimation of the time covariance of the residuals. This enabled the delimitation of the cave into three zones of varying environmental risk in the event of being opened to visits by the public, according to the degree of stability of air temperature over space and time. The influence of human presence on the spatial temperature distribution was assessed using data collected during a year (2000/2001) in pilot galleries opened to the public. An average visit corresponding to August was selected comprising 16 people over a period of 53 min. This average visit influenced the spatial temperature pattern at distances of more than 90 m from the cave entrance, according to the geostatistical model adopted. Within this zone the mean thermal increment generated by human presence was estimated to be 0.26 °C. The spatiotemporal mathematical model of the cave air temperature has been revealed as a useful tool for the environmental management of show caves.