Uranium-series analyses of water-table-type speleothems from Glenwood Cavern and “cavelets” near the town of Glenwood Springs, Colorado, USA, yield incision rates of the Colorado River in Glenwood Canyon for the last ~1.4 My. The incision rates, calculated from dating cave mammillary and cave folia calcite situated 65 and 90 m above the Colorado River, are 174 ± 30 m/My for the last 0.46 My and 144 ± 30 m/My for the last 0.62 My, respectively. These are consistent with incision rates determined from nearby volcanic deposits. In contrast, δ 234U model ages (1.39 ± 0.25 My; 1.36 ± 0.25 My; and 1.72 ± 0.25 My) from three different samples of mammillary-like subaqueous crust collected from Glenwood Cavern, 375 m above the Colorado River, yield incision rates of 271 +58/-41 m/My, 277 +61/-42 m/ My, and 218 +36/-27 m/My. These data suggest a relatively fast incision rate between roughly 3 and 1 Ma. The onset of Pleistocene glaciation may have influenced this rate by increasing precipitation on the Colorado Plateau starting at 2.5 Ma. Slowing of incision just before 0.6 Ma could be related to the change in frequency of glacial cycles from 40 to 100 kyr in the middle Pleistocene. This interpretation would suggest that the cutting power of the Colorado River prior to 3 Ma was smaller. An alternative interpretation involving tectonic activity would invoke an episode of fast uplift in the Glenwood Canyon region from 3 to 1 Ma.

Electrical and electromagnetic geophysical characterization is a proven tool for delineating obscured subterranean karstic features, such as caves, sinkholes, and solution enlarged fissures. Geophysical characterizations allow a wide range of deployment scales; airborne methods can accommodate a regional view on the order of kilometers, and ground-based methods can follow up with focused data on the order of meters. A helicopter frequency domain electro-magnetic (HFDEM) survey and ground-based direct-current electrical resistivity imaging (DC-ERI) geophysical studies at the Camp Bullis Military Training Site (Camp Bullis) in central Texas have been used to characterize permeability properties of the Edwards and Trinity Aquifers in the area. Results of three separate investigations identified zones of high density karst features and characterized specific karstic voids, including caves. In 2003, the USGS completed an HFDEM survey of Camp Bullis and nearby areas to map and image subsurface features related to the groundwater resources. The survey refined locations of mapped and previously unmapped faults and characterized the heterogeneity of the subsurface electrical signature. Karst mapping at Camp Bullis identified over 1500 features, and high density zones of features correspond with areas of high resistivity from the HEM data. DC-ERI surveys at several locations were used to infer and characterize known and hypothesized karst features. Site 8 suggests an inferred fault and 195dissolution feature. Two other sites were surveyed near major caves that directly recharge the Trinity Aquifer (indirectly to Edwards Aquifer) along Cibolo Creek. Integration of multi-scale geophysical datasets could be used to augment aquifer-wide recharge characterization and quantification.

Three of the approximately twenty-three municipal wastewater treatment lagoons constructed in the 1970s and 1980s in southeastern Minnesota’s karst region have failed through sinkhole collapse. Those collapses occurred between 1974 and 1992. All three failures occurred at almost exactly the same stratigraphic position. That stratigraphic interval, just above the unconformable contact between the Shakopee and Oneota Formations of the Ordovician Prairie du Chien Group is now recognized as one of the most ubiquitous, regional-scale, karst hydraulic high-transmissivity zones in the Paleozoic hydrostratigraphy of southeastern Minnesota. These karst aquifers have been developing multi-porosity conduit flow systems since the initial deposition of the carbonates about 480 million years ago. The existence of syndepositional interstratal karst unconformities between the Oneota and Shakopee Formations and between the Shakopee and St. Peter Formations, were recognized in the 1800s. About 270 million years ago galena, sphalerite and iron sulfides were deposited in pre-existing solution enlarged joints, bedding planes and caves. The region has been above sea level since the Cretaceous and huge volumes of fresh water have flowed through these rocks. The regional flow systems have changed from east-to-west in the Cenozoic, to north-to-south in or before the Pleistocene. The incision of the Mississippi River and its tributaries has and is profoundly rearranging the ground water flow systems as it varies the regional base levels during glacial cycles. The Pleistocene glacial cycles have removed many of the surficial karst features and buried even more of them under glacial sediments. High erosion rates from row crop agriculture between the us1850s and 1930s filled many of the conduit systems with soil. Over eighty years of soil conservation efforts have significantly reduced the flux of mobilized soil into the conduits. Those conduits are currently flushing much of those stored soils out of their spring outlets. Finally, the increased frequency and intensity of major storm events is reactivating conduit segments that have been clogged and inactive for millions of years.The karst solution voids into which the lagoons collapsed have formed over 480 million years. The recognition and mapping of this major karst zone will allow much more accurate karst hazard maps to be constructed and used in sustainable resource management decisions.

The Salman Farsi dam project is constructed on the Ghareh Agahaj River about 140km south of Shiraz city in the Zagros Mountains of southwestern Iran. This tectonic province of southwestern Iran is characterized by a simple folded sedimentary sequence. The dam foundation rocks compose of the Asmari Formation of Oligo-miocene and generally comprise of a variety of karstified carbonate rocks varying from strong to weak rocks. Most of the rocks exposed at the dam site show a primary porosity due to incomplete diagenetic recrystallization and compaction. In addition to these primary dispositions to weathering, layering conditions (frequency and orientation of bedding) and the subvertical tectonic discontinuities channeled preferably the infiltrating by deep-sited hydrothermal solutions. Consequently the porosity results to be enlarged by dissolution and the rocks are expected to be karstified and to develop cavities in correspondence of bedding, major joint planes and fault zones. This kind of karsts is named hypogenic karsts which associated to the ascendant warm solutions. Field observations indicate strong karstification and vuggy intercalations especially in the middle part of the Asmari succession. The biggest karst in the dam axis which identified by speleological investigations is Golshany Cave with volume of about 150,000 m3. The tendency of the Asmari limestone for strong dissolution can alert about the seepage from the reservoir and area of the dam locality

The Salman Farsi dam project is constructed on the Ghareh Agahaj River about 140km south of Shiraz city in the Zagros Mountains of southwestern Iran. This tectonic province of southwestern Iran is characterized by a simple folded sedimentary sequence. The dam foundation rocks compose of the Asmari Formation of Oligo-miocene and generally comprise of a variety of karstified carbonate rocks varying from strong to weak rocks. Most of the rocks exposed at the dam site show a primary porosity due to incomplete diagenetic recrystallization and compaction. In addition to these primary dispositions to weathering, layering conditions (frequency and orientation of bedding) and the subvertical tectonic discontinuities channeled preferably the infiltrating by deep-sited hydrothermal solutions. Consequently the porosity results to be enlarged by dissolution and the rocks are expected to be karstified and to develop cavities in correspondence of bedding, major joint planes and fault zones. This kind of karsts is named hypogenic karsts which associated to the ascendant warm solutions. Field observations indicate strong karstification and vuggy intercalations especially in the middle part of the Asmari succession. The biggest karst in the dam axis which identified by speleological investigations is Golshany Cave with volume of about 150,000 m3. The tendency of the Asmari limestone for strong dissolution can alert about the seepage from the reservoir and area of the dam locality.

The Salman Farsi dam project is constructed on the Ghareh Agahaj River about 140km south of Shiraz city in the Zagros Mountains of southwestern Iran. This tectonic province of southwestern Iran is characterized by a simple folded sedimentary sequence. The dam foundation rocks compose of the Asmari Formation of Oligo-miocene and generally comprise of a variety of karstified carbonate rocks varying from strong to weak rocks. Most of the rocks exposed at the dam site show a primary porosity due to incomplete diagenetic recrystallization and compaction. In addition to these primary dispositions to weathering, layering conditions (frequency and orientation of bedding) and the subvertical tectonic discontinuities channeled preferably the infiltrating by deep-sited hydrothermal solutions. Consequently the porosity results to be enlarged by dissolution and the rocks are expected to be karstified and to develop cavities in correspondence of bedding, major joint planes and fault zones. This kind of karsts is named hypogenic karsts which associated to the ascendant warm solutions. Field observations indicate strong karstification and vuggy intercalations especially in the middle part of the Asmari succession. The biggest karst in the dam axis which identified by speleological investigations is Golshany Cave with volume of about 150,000 m3. The tendency of the Asmari limestone for strong dissolution can alert about the seepage from the reservoir and area of the dam locality

The vertical organisation of karst conduit networks has been the focus of speleogenetic studies for more than a century. The four state model of Ford and Ewers (1978), which still is considered as the most general, relates the geometry of caves to the frequency of permeable fissures. The model suggests that the ‘water table caves’ are common in areas with high fissure frequency, which is often the case in natural settings. However, in Alpine karst systems, water table caves aremore the exception than the rule. Alpine speleogenesis is influenced by high uplift, valley incision rates and irregular recharge. To study the potential role of these processes for speleogenesis in the dimensions of length and depth, we apply a simple mathematical model based on coupling of flow, dissolution and transport.We assume a master conduit draining thewater to the spring at a base level. Incision of the valley triggers evolution of deeper flow pathways,which are initially in a proto-conduit state. Themaster conduit evolves into a canyon following the valley incision,while the deep pathways evolve towards maturity and tend to capture the water fromthe master conduits. Two outcomes are possible: a) deep pathways evolve fast enough to capture all the recharge, leaving the master conduit dry; or b) the canyon reaches the level of deep pathways before these evolve to maturity. We introduce the Loop-to-Canyon Ratio (LCR), which predicts which of the two outcomes is more likely to occur in certain settings. Our model is extended to account for transient flow conditions. In the case of an undulating master conduit, floodwater is stored in troughs after the flood retreat. This water seeps through sub-vertical fractures (‘soutirages’) connecting the master conduitwith the deep pathways. Therefore, the loops evolve also during the dry season, and the LCR is considerably increased. Although themodel is based on several approximations, it leads to some important conclusions for vertical organisation of karst conduit networks and stresses the importance of base-level changes and transient recharge conditions. It therefore gives an explanation of speleogenesis that relies much more on the dynamic nature of water flow than on the static fracture density

Speleothems are usually composed of thin layers of calcite (or aragonite). However,
cemented detrital materials interlayered between laminae of speleothemic carbonate have been also observed in many caves. Flowstones comprising discontinuous carbonate layers form due to flowing water films,while flood events introduce fluviokarstic sediments in caves that, on occasion,are recorded as clayey layers inside flowstones and stalagmites. This record provides a potential means of understand­ing the frequency of palaeofloods using cave records.In this work,we investigate the origin of this type of detritaldeposit in El Soplao Cave (Northern Spain). The age of the lowest aragonite layer
of a flowstone reveals that the earliest flood period occurred before 500 ka, though most of the flowstone formed between 422 +69/-43 ka and 400 +66/-42 ka. This suggests that the cave was periodically affected by palaeoflood events that introduced detrital sediments from the surface as a result of occasional extreme rainfall events,especially at around 400 ka.The mineralogical data enable an evolutionary modelfor this flowstone to be generated based on the alternation offload events with laminar flows and carbonate layers precipitation that can be extrapolated to other caves in which detrital sediments inside speleothems have been found. 

In scarcity of light and primary producers, subterranean ecosystems are generally extremely oligotrophic habitats, receiving poor supplies of degradable organic matter from the surface. Human direct impacts on cave ecosystems mainly derive from intensive tourism and recreational caving, causing important alterations to the whole subterranean environment. In particular, artificial lighting systems in show caves support the growth of autotrophic organisms (the so-called lampenflora), mainly composed of cyanobacteria, diatoms, chlorophytes, mosses and ferns producing exocellular polymeric substances (EPSs) made of polysaccharides, proteins, lipids and nucleic acids. This anionic EPSs matrix mediates to the intercellular communications and participates to the chemical exchanges with the substratum, inducing the adsorption of cations and dissolved organic molecules from the cave formations (speleothems). Coupled with the metabolic activities of heterotrophic microorganisms colonising such layer (biofilm), this phenomenon may lead to the corrosion of the mineral surfaces. In this review, we investigate the formation of biofilms, especially of diatom-dominated ones, as a consequence of artificial lighting and its impacts on speleothems. Whenever light reaches the subterranean habitat (both artificially and naturally) a relative high number of species of diatoms may indeed colonise it. Cave entrances, artificially illuminated walls and speleothems inside the cave are generally the preferred substrates. This review focuses on the diatom flora colonising subterranean habitats, summarizing the information contained in all the scientific papers published from 1900 up to date. In this review we provide a complete checklist of the diatom taxa recorded in subterranean habitats, including a total of 363 taxa, belonging to 82 genera. The most frequent and abundant species recorded in caves and other low light subterranean habitats are generally aerophilic and cosmopolitan. These are, in order of frequency: Hantzschia amphioxys, Diadesmis contenta, Orthoseira roeseana, Luticola nivalis, Pinnularia borealis, Diadesmis biceps and Luticola mutica. Due to the peculiarity of the subterranean habitats, the record of rare or new species is relatively common. The most important environmental factors driving species composition and morphological modifications observed in subterranean populations are analysed throughout the text and tables. In addition, suggestions to prevent and remove the corrosive biofilms in view of an environmentally sustainable cave management are discussed.

Porosity and permeability along fractured zones in carbonates could be significantly enhanced by ascending fluid flow, resulting in hypogene karst development. This work presents a detailed structural analysis of the longest cave system in South America to investigate the relationship between patterns of karst conduits and regional deformation. Our study area encompasses the Toca da Boa Vista (TBV) and Toca da Barriguda (TBR) caves, which are ca. 107 km and 34 km long, respectively. This cave system occurs in Neoproterozoic carbonates of the Salitre Formation in the northern part of the São Francisco Craton, Brazil. The fold belts that are around and at the craton edges were deformed in a compressive setting during the Brasiliano orogeny between 750 and 540 Ma. Based on the integrated analysis of the folds and brittle deformation in the caves and in outcrops of the surrounding region, we show the following: (1) The caves occur in a tectonic transpressive corridor along a regional thrust belt; (2) major cave passages, at the middle storey of the system, considering both length and frequency, developed laterally along mainly (a) NE–SW to E–W and (b) N to S oriented anticline hinges; (3) conduitswere formed by dissolutional enlargement of subvertical joints,which present a high concentration along anticline hinges due to folding of competent grainstone layers; (4) the first folding event F1was previously documented in the region and corresponds with NW–SE- to N–S-trending compression, whereas the second event F2, documented for the first time in the present study, is related to E–Wcompression; and (5) both folding  еvents occurred during the Brasiliano orogeny. We conclude that fluid flow and related dissolution pathways have a close relationship with regional deformation events, thus enhancing our ability to predict karst patterns in layered carbonates.