Cave: natural cavity in a rock which is enterable by people.
Karst: a terrain that is formed principally by the solution of the rock.
Caves constitute a disproportionately large part of the surviving archaeological record for many prehistoric periods (Straus, 1997). Their stability in the landscape attracted humans in search of shelter early in the history of humankind, and at the same time, they facilitated the accumulation of sediment and cultural material. The lengthy geologic and archaeological record that has built up within some caves provides the basic data of prehistoric archaeology in many regions of the world. Caves are also parts of drainage systems as well as ground water flow paths, making them important water sources that may partly explain their early use. It has been suggested that caves provide ready-made natural structures without the need of any significant adaptation of human behavior, and in this way, they were convenient and useful for a variety of purposes (Skeates, 1997; Straus, 1997). Caves are an example of bounded space, and like architectural forms, they can be carefully manipulated to create inhabitable, delineated areas where such spaces do not exist in nature (Kent, 1990). As such, caves provide not only natural shelter and protection but also a memorable and confined living space with a sense of durability and familiarity, probably precursors of the modern idea of “home.” Caves, therefore, have been considered to be the first “home base” sites during the late Middle Pleistocene (Rolland, 2004).
Caves have varying and changing uses across different cultures. Early in the evolution of humans, they were the focus of hominin occupation. Examples include the famous caves within the Cradle of Humankind in South Africa, where important early hominin fossils have been found (e.g., Pickering and Kramers, 2010). However, it is believed that widespread, regular cave occupation did not begin before later Acheulian horizons, and not until the Middle Paleolithic are caves more systematically exploited. The use of fire made deep caves available for specialized ritual functions, as is indicated by the Upper Paleolithic art caves of France and Spain. Later, during the Neolithic, an expansion of cave use is observed, as groups exploited cave spaces as part of a pastoral economy (Tolan-Smith and Bonsall, 1997). In addition to dwellings, caves have also been employed as storage sites, cooking places, cemeteries, and temples.
Water circulation is also greater near joints, bedding planes, and faults. Therefore, in the early stages of their formation, caves act as water conduits. When water-filled passages drain, hydrostatic support stops and breakdown commences. In any cave evolution sequence, the spalling of wall and ceiling surfaces is an inevitable phase that leads to partial or complete infilling but also to enlarging and generally changing the configuration of the cave (Gillieson, 1996). Other mechanisms of cave development in carbonate rocks include dissolution by sulfuric acid produced from upwelling thermal waters that oxidize sulfides present in the limestone or from oxidized hydrogen sulfide emanating from deep hydrocarbon sources. Sulfur-oxidizing and sulfur-reducing bacteria are involved in this type of speleogenesis (White, 2000).
Caves may occur in sandstones and quartzites, evaporates (e.g., gypsum), igneous rocks such as basalts and granites, as well as in ice. In some of these cases, dissolution is also the major factor of cave formation, particularly in sandstones and evaporitic rocks. In sandstones, if the cementing material is carbonate, then cave formation will proceed according to the karstification process described above. In quartzites and sandstones, silica cement dissolution is very slow, and mechanical removal of loosened grains by fast moving groundwater is an additional process leading to enlargement (Martini, 2000). Caves in basalt are often lava caves formed by the draining of lava tube feeding networks during the eruption period.
Detailed study of the formation of caves, as well as their history prior to human occupation, is normally not undertaken in archaeological projects. Yet, such studies contribute significantly to our understanding of the paleoenvironment and evolution of the landscape, and they can reveal potential links to the eventual presence of humans. In addition, the processes responsible for a cave’s formation are often ongoing, albeit at a slower rate, throughout its entire history, and consequently they affect or determine the type of deposits, structure, and location. For example, Qesem Cave in Israel was formed by a combination of processes that include subsidence and sagging of the bedrock into deeper voids formed by deep-seated dissolution (Frumkin et al., 2009). The gradual sagging of the basal bedrock layers also affected the overlying sediments such that the cemented parts of the cave deposits (indurated through hardening of the matrix) have fractured along the walls allowing the central area to sink through gravitational slumping. These processes have resulted in hanging ledges of cemented deposits clinging to the cave walls while the adjacent sunken area in the center subsequently filled in. Then everything was covered with new collapse material. Both the complex stratigraphy and the sedimentary character of the cave are better explained when the processes responsible for cave formation are clearly understood (Karkanas et al., 2007).
Caves are often perfect sedimentary traps, accumulating and protecting the stratigraphic record from many postdepositional subaerial processes. Cave sedimentary facies are quite useful in interpreting and reconstructing depositional histories, which can track changes in earth system processes (Springer, 2012), thereby yielding insights into climate and landscape evolution within the area (Goldberg, 2000; Pickering et al., 2007; Karkanas et al., 2008; Kourampas et al. 2009). Sediments from different sources accumulate within caves, and thus complex stratigraphic sequences may result. At the same time, however, such instances provide some of the best cases for studying past human behavior (Macphail et al., 1997; Karkanas et al., 2007; Meignen et al., 2007; Goldberg et al., 2009).
Secondary clastic sediments from the outside (allochthonous or exogenous) enter the cave through a variety of processes, such as fluvial deposition, aeolian activity, and mass movement (debris and mudflows, creep, falls, slumps, etc.). The main sources of this sediment are sinking streams carrying sediments from nearby drainage basins, soils, and weathering residuum from the ground surface that are flushed into caves through sinkholes and open fractures by storm runoff and sediment influxes from overlying rock formations through open fractures (Bosch and White, 2004).
Another fine-grained sediment frequently observed in archaeological caves is infiltrated fine-grained sediment and soil flushed through joints, fractures, and generally thin discontinuities of the bedrock (Figure 3). This sediment is often deposited as hyperconcentrated slurries and mudflows producing cones where they exit from the joints. More diluted flows can slowly percolate inside coarser roofspall and accumulate within the voids, thereby creating secondary-filled, matrix-supported angular gravels. Piles of coarse breakdown deposits can be further redistributed by gravity when lubricated by infiltrated clay slurries (Karkanas et al., 2007).
In coastal areas, aeolian deposition is widespread. Several important sites along the coast of South Africa and the Mediterranean are dominated by windblown deposits of well-sorted sand interfingered with anthropogenic sediments (Figure 2) (Goldberg, 1973, Deacon and Geleijnse, 1988; Tsatskin et al., 1995; Goldberg 2000; Macphail and Goldberg, 2000; Jacobs et al., 2006; Karkanas and Goldberg, 2010). Aeolian silt (dust) is also an important component of cave sediments – particularly in the circum-Mediterranean zone – but due to its slow accumulation rate, it is often intermixed with coarser roofspall, aeolian sand, and other clastic or anthropogenic components, such as the similar-sized wood ash. These mixtures make the interpretation of such sediments very difficult in the field. In Dust Cave, Alabama, USA, original aeolian silts occur as rounded soil aggregates and are incorporated within the coarser deposits. Here, dust originated in the nearby floodplain of the Tennessee River and along the limestone bluffs above the cave, and it was transported directly and indirectly into the cave by different mechanisms (Sherwood et al., 2004; Goldberg and Sherwood, 2006). In general, aeolian deposits are quite loose and easily disturbed by secondary sedimentary processes. Water seeping from fractures in cave walls or flushed through conduits can redistribute aeolian sediment and produce finely laminated deposits (Goldberg, 2000).
Primary chemical sediments are mainly in the form of speleothems (stalagmites, stalactites, flowstones, etc.). They are deposited by carbonate-saturated dripping, seeping, or flowing waters on the surface of the caves. These sediments are suitable for high-resolution dating such as uranium-series techniques, and when intercalated with clastic sediments, they can provide secure stratigraphic and chronostratigraphic markers (Moriarty et al., 2000; Pickering et al., 2007).
Primary biogenic sediments are mainly represented by the accumulation of large amounts of bat guano but also excrements from other animals that occupy cave interiors (bears, hyenas, etc.). The decay of biogenic sediments leads to chemical alteration of all previously deposited sediments and the formation of a suite of authigenic phosphate minerals (Karkanas et al., 2000; Shahack-Gross et al., 2004). Diagenesis is often very aggressive in caves because they also contain an active and confined hydrologic regime (for the details of these diagenetic processes, see the entry on “ Chemical Alteration”). As several studies in the Near East and Europe have shown, phosphate diagenesis can have a dramatic effect upon the preservation of archaeological materials, leading to complete dissolution of bones and all kinds of calcareous materials such as ash, shells, and limestone particles (Goldberg and Nathan, 1975; Weiner and Bar-Yosef, 1990; Weiner et al., 1993; Schiegl et al., 1996; Karkanas et al., 1999; Karkanas et al., 2000; Karkanas et al., 2002; Weiner et al., 2002).
Transported and introduced natural clastic sediments are also encountered in cave sequences. In several cases, prehistoric constructions such as clay hearths and platforms have been identified, representing outside materials accumulated and shaped into man-made structures (Karkanas et al., 2004; Goldberg and Sherwood, 2006). Nonetheless, one of the most important but also neglected aspects of human-induced sedimentary processes is the redistribution and general (often penecontemporaneous) reworking of previously deposited geogenic or anthropogenic sediments by human activities. The digging of pits, dumping of burnt remains and food refuse, sweeping or shoveling out of stable residues, and trampling are among the most common secondary anthropogenic processes that rearrange sediment (Goldberg and Sherwood, 2006). Since these processes alter primary sedimentary structures and tend to mix contents and textures, they are generally difficult to discern and interpret by eye in the field. These effects can be studied with the proper analytical tools, and the results of such examinations can considerably enhance our knowledge of human behavior.
Methods of study
Caves were one of the first environments in which sedimentological techniques, such as grain-sized analysis, particle shape and composition, pH, and calcium carbonate and organic matter content, were applied to the study of archaeological deposits in order to interpret the depositional history of cave sediments (Bordes, 1972; Laville et al., 1980; Farrand, 2000). Although these data can provide useful quantitative information in some cases, they have mostly failed to (1) identify important anthropogenic components, such as calcareous ash, and (2) disentangle the complex syndepositional and postdepositional processes related to geogenic, biogenic, and anthropogenic activities. Indeed, as early as the 1970s, it was realized that classical sedimentological analyses did not reveal important postdepositional processes that constitute the basis of paleoclimatic interpretations (Goldberg, 1979a). Archaeological cave sediments were also the first to be studied by micromorphology, the study of intact sediments and soils under the microscope (Goldberg, 1979a; Goldberg, 1979b; Courty et al., 1989). Micromorphology is the best technique for unraveling such complex processes, and it provides the initial and basic framework for applying other techniques that can further elucidate details of both sedimentary accumulation and diagenetic changes. High-resolution approaches such as SEM, EDAX, XRD, and FTIR have been employed in the study of archaeological cave sediments along with micromorphology (Goldberg and Nathan, 1975; Bull and Goldberg, 1985; Weiner et al., 1993; Schiegl et al., 1996; Karkanas et al., 1999).
Cave sediments and environmental change
The usefulness of caves as archives of environmental change is controlled by the temporal resolution of the sedimentary record and the environmental sensitivity of the cave (Woodward and Goldberg, 2001). Studying caves as parts of the regional geomorphic system enables inferences relating to climatic and other changes in the regime of landscape processes for the entire area (Gillieson, 1996). There are, however, some limitations when trying to reconstruct paleoclimate using cave sediments. First, local factors govern the microclimate of the cave and may play a significant role in the way internal sedimentation occurs. Caves are complex settings with a unique microenvironment that is influenced by bedrock lithology, elevation, aspect, local drainage, internal configuration, and human activity (Goldberg and Sherwood, 2006). Second, caves are parts of larger karstic systems where sediments are circulating and stored for considerable periods of time before ultimately being deposited within the cave under study. This lag effect hampers easy interpretations based on weathering indices of external soil sources of the surrounding area. Fortunately in many regions, caves preserve distinct suites of sedimentary features that can provide the best available terrestrial record when combined with detailed stratigraphic analysis and comprehensive field observations, then corroborated by instrumental laboratory analysis.
The earliest micromorphological studies conducted on cave sediments in the Dordogne region of France clearly demonstrated episodes of colluviation, flowstone, and stalactite formation, alternating with ice lensing and cryoclastism (Goldberg, 1979a; Courty, 1989). Frost-related processes affecting fine-grained sediments, such as cryoturbation and ice lensing, are particularly informative about climatic changes in caves (van Vliet-Lanoë, 1985) (Figure 4). Clastic deposits showing evidence of frost action may alternate with non-affected sediment or flowstones, which generally form during warmer climatic conditions. However, even in these cases, prior to a final interpretation, other environmental indices should be considered, such as phytoliths, charcoal, and macrobotanical remains, along with a thorough micromorphological analysis of the deposits. For example, flowstones intercalating with frost-affected sediments would be typically considered to be an indicator of warmer climate intervals. However, there are cases where flowstones can also be deposited under cold climate regimes (Bar-Matthews and Ayalon, 2011), and they themselves can also be affected by frost action (Courty et al., 1989; Karkanas et al., 2008). It should be remembered that sediments affected by frost action may have been deposited already and were not necessarily formed during a cold climate. In the end, it is the association and spatial distribution of all sedimentary features, both primary deposits and secondary disturbances, that ultimately lead to a thorough understanding of the sedimentary processes and stratigraphy of a cave site.
Finally, recent advances in dating techniques and isotopic analyses have made speleothem records the key proxy in reconstructing paleoclimatic change (e.g., Cheng et al., 2009). Highly detailed analysis of speleothem laminae can produce a yearly or even seasonal climatic record, and these complete climatic records can be compared to the archaeological record. Important inferences about cultural transitions, social changes, and even the collapse of civilizations (Bar-Matthews and Ayalon, 2011) can be made, though the exact role played by these detailed climatic changes in influencing human behavior must still be demonstrated with further evidence.
Cave sediments and human behavior
As mentioned above, the use of fire is of major importance to understanding human behavior in prehistory. Claims for early control of fire have been challenged by studies of cave sediments using micromorphology and FTIR. In Zhoukoudian, China, the purported burnt features were found to consist of dark brown and reddish-brown, finely laminated silts and clays interbedded with decayed fragments of organic matter. The sediments were therefore not the result of in situ burning as was previously interpreted based on field observations, but they were instead deposited in standing or slow-flowing water (Goldberg et al., 2001). In contrast, the Middle Pleistocene cave of Qesem, Israel, contains sediments that appear in the field as a light reddish-brown, strongly lithified, and mostly massive deposit that archaeologists recognize as a common fill of angular rock fragments and matrix called “cave breccia.” Based on micromorphological observations as well as mineralogical and isotopic analysis, however, it was discovered that a considerable part of these sediments in fact consist of recrystallized wood ash, indicating the presence of fire in antiquity (Karkanas et al., 2007).
In caves, combustion features can be well preserved, thus offering a clear picture of the burning activities related to them. In Kebara Cave, Israel, field observations and micromorphology revealed a variety of features including massive accumulations and small patches of charcoal and ashes, intact hearth structures, and diffuse ashy lenses. The geometry, composition, and microstructure of each of these types of deposits provided information on specific fire-related activities and events such as dumping, trampling, and cleaning that can place other archaeological materials into the context of a living settlement (Goldberg et al., 2007; Meignen et al., 2007).
In Dust Cave, Alabama, USA, prepared thin clay constructions were identified within Paleo-Indian strata based on field and micromorphological observations. As these features preserved intact lenses of ash, they provided data on fuel, feature type, and function. It was thus suggested that these flat clay structures were used as special heated cooking surfaces for roasting or specialized food processing (Sherwood and Chapman, 2005). Similar structures have been also identified in the Aurignacian sequence of Klissoura Cave 1, Greece. Here, micromorphology corroborated by FTIR and differential thermal analyses (DTA) revealed that the clay structures were heated in place at relatively low temperatures (400–600 °C), implying that they were also used as hearths for special cooking activities (Karkanas et al., 2004).
Study of cave sediments from later periods has offered insights into questions related to the nature of cave occupation, their monofunctional or polyfunctional uses, differences in the exploitation of site space, and the seasonality of occupation (Courty et al., 1991; Boschian and Montagnari-Kokelj, 2000; Angelucci et al., 2009). Several studies have shown that that during the Neolithic, caves were used both for herbivore stabling and for domestic occupation and that different areas within the caves were used for each purpose (Macphail et al., 1997; Karkanas, 2006).
Caves occupy an important place in archaeology and environmental studies. As unique landforms within the earth, they act as sediment repositories preserving detailed records of human activities and paleoenvironmental changes. Sedimentary sequences within caves comprise not only a suite of primary and secondary clastic sediments but also primary chemical and biogenic sediments, as well as secondary alteration deposits. Human activities add to the complexity of the sedimentary processes by adding organic-rich deposits, combustion features, and the reworking of previously deposited sediments. Despite these complications, detailed sedimentological studies at the microscopic scale supplemented by high-resolution instrumental techniques can untangle these complex processes, offering some of the best opportunities to study early human behavior.
- Bordes, F., 1972. A Tale of Two Caves. New York: Harper and Row.Google Scholar
- Bosch, R. F., and White, W. B., 2004. Lithofacies and transport of clastic sediments in karstic aquifers. In Sasowsky, I. D., and Mylroie, J. (eds.), Studies of Cave Sediments. Physical and Chemical Records of Paleoclimate. New York: Kluwer Academic/Plenum Publishers, pp. 1–22.CrossRefGoogle Scholar
- Courty, M.-A., 1989. Analyse microscopic des sédiments du remplissage de la grotte de Vaufrey (Dordogne). In Rigaud, J.-P. (ed.), La Grotte Vaufrey à Cenac-et-Saint Julien (Dordogne): Paleoenvironments, chronologie et activités humaines. Paris: Ministère de la culture et de la communication & CNRS. Mémoires de la Societé préhistorique française, Vol. 19, pp. 183–209.Google Scholar
- Courty, M.-A., Goldberg, P., and Macphail, R. I., 1989. Soils and Micromorphology in Archaeology. Cambridge: Cambridge University Press.Google Scholar
- Courty, M.-A., Macphail, R. I., and Wattez, J., 1991. Soil micromorphological indicators of pastoralism; with special reference to Arene Candide, Finale Ligure, Italy. Rivista di Studi Liguri, 57, 127–150.Google Scholar
- Farrand, W. R., 2000. Depositional History of Franchthi Cave. Sediments, Stratigraphy, and Chronology. Bloomington/Indianapolis: Indiana University Press. Excavations at Franchthi Cave, Fascicle, Vol. 12.Google Scholar
- Goldberg, P., 1973. Sedimentology, Stratigraphy and Paleoclimatology of et-Tabun Cave, Mount Carmel, Israel. PhD Dissertation, Dept. of Geological Sciences, University of Michigan, Ann Arbor.Google Scholar
- Goldberg, P., Laville, H., and Meignen, L., 2007. Stratigraphy and geoarchaeological history of Kebara Cave, Mount Carmel. In Bar-Yosef, O., and Meignen, L. (eds.), Kebara Cave, Part 1. Cambridge: Peabody Museum of Archaeology and Ethnology, Harvard University, pp. 49–89.Google Scholar
- Karkanas, P., Koumouzelis, M., Kozlowski, J. K., Sitlivy, V., Sobczyk, K., Berna, F., and Weiner, S., 2004. The earliest evidence for clay hearths: Aurignacian features in Klisoura Cave 1, southern Greece. Antiquity, 78(301), 513–525.Google Scholar
- Karkanas, P., Shahack-Gross, R., Ayalon, A., Bar-Matthews, M., Barkai, R., Frumkin, A., Gopher, A., and Stiner, M. C., 2007. Evidence for habitual use of fire at the end of the Lower Paleolithic: site-formation processes at Qesem Cave, Israel. Journal of Human Evolution, 53(2), 197–212.CrossRefGoogle Scholar
- Kent, S., 1990. Activity areas and architecture: an interdisciplinary view of the relationship between use of space and domestic environments. In Kent, S. (ed.), Domestic Architecture and the Use of Space. Cambridge: Cambridge University Press, pp. 1–8.Google Scholar
- Kourampas, N., Simpson, I. A., Perera, N., Deraniyagala, S. U., and Wijeyapala, W. H., 2009. Rockshelter sedimentation in a dynamic tropical landscape: Late Pleistocene-Early Holocene archaeological deposits in Kitulgala Beli-Lena, southwestern Sri Lanka. Geoarchaeology, 24(6), 677–714.CrossRefGoogle Scholar
- Laville, H., Rigaud, J.-P., and Sackett, J., 1980. Rock Shelters of the Perigord. New York: Academic.Google Scholar
- Macphail, R. I., and Goldberg, P., 2000. Geoarchaeological investigation of sediments from Gorham’s and Vanguard caves, Gibraltar: microstratigraphical (soil micromorphological and chemical) signatures. In Stringer, C. B., Barton, R. N. E., and Finlayson, J. C. (eds.), Neanderthals on the Edge. Oxford: Oxbow Books, pp. 183–200.Google Scholar
- Macphail, R. I., Courty, M.-A., Hather, J., and Wattez, J., 1997. The soil micromorphological evidence of domestic occupation and stabling activities. In Maggi, R. (ed.), Arene Candide: A Functional and Environmental Assessment of the Holocene Sequence: Excavations Bernabò Brea-Cardini (1940–50). Rome: Il Calamo. Memorie dell’Istituto Italiano di Paleontologia Umana, Vol. 5, pp. 53–88.Google Scholar
- Macphail, R. I., and Goldberg, P., 2003. Gough’s Cave, Cheddar, Somerset: microstratigraphy of the Late Pleistocene/earliest Holocene sediments. Bulletin of the Natural History Museum: Geology, 58(Supplement S1), 51–58.Google Scholar
- Martini, J. E. J., 2000. Dissolution of quartz and silicate minerals. In Klimchouk, A., Ford, D. C., Palmer, A. N., and Dreybrodt, W. (eds.), Speleogenesis. Evolution of Karst Aquifers. Huntsville: National Speleological Society, pp. 171–174.Google Scholar
- Meignen, L., Goldberg, P., and Bar-Yosef, O., 2007. The hearths at Kebara Cave and their role in site formation processes. In Bar-Yosef, O., and Meignen, L. (eds.), Kebara Cave, Part 1. Cambridge, MA: Peabody Museum of Archaeology and Ethnology, Harvard University, pp. 91–122.Google Scholar
- Moriarty, K. C., McCulloch, M. T., Wells, R. T., and McDowell, M. C., 2000. Mid-Pleistocene cave fills, megafaunal remains and climate change at Naracoorte, South Australia: towards a predictive model using U-Th dating speleothems. Palaeogeography Palaeoclimatology Palaeoecology, 159(1–2), 113–143.CrossRefGoogle Scholar
- Mylroie, J. E., 2005. Coastal caves. In Culver, D. C., and White, W. B. (eds.), Encyclopedia of Caves. Amsterdam: Elsevier, pp. 122–127.Google Scholar
- Mylroie, J. E., and Carew, J. L., 2000. Speleogenesis in coastal and oceanic settings. In Klimchouk, A. B., Ford, D. C., Palmer, A. N., and Dreybrodt, W. (eds.), Speleogenesis: Evolution of Karst Aquifers. Huntsville: National Speleological Society, pp. 226–233.Google Scholar
- Pickering, R., Hancox, P. J., Lee-Thorp, J. A., Grün, R., Mortimer, G. E., McCulloch, M., and Berger, L. R., 2007. Stratigraphy, U-Th chronology, and paleoenvironments at Gladysvale Cave: insights into the climatic control of South African hominin-bearing cave deposits. Journal of Human Evolution, 53(5), 602–619.CrossRefGoogle Scholar
- Sherwood, S. C., and Chapman, J., 2005. The identification and potential significance of early Holocene prepared clay surfaces: examples from Dust Cave and Icehouse Bottom. Southeastern Archaeology, 24(1), 70–82.Google Scholar
- Skeates, R., 1997. The human uses of caves in east-central Italy during the Mesolithic, Neolithic and Copper Age. In Bonsall, C., and Tolan-Smith, C. (eds.), The Human Use of Caves. Oxford: Archaeopress. British Archaeological Reports, International Series, Vol. 667, pp. 79–86.Google Scholar
- Straus, L. G., 1997. Convenient cavities: some human uses of caves and rockshelters. In Bonsall, C., and Tolan-Smith, C. (eds.), The Human Use of Caves. Oxford: Archaeopress. British Archaeological Reports, International Series, Vol. 667, pp. 1–8.Google Scholar
- Tolan-Smith, C., and Bonsall, C., 1997. The human use of caves. In Bonsall, C., and Tolan-Smith, C. (eds.), The Human Use of Caves. Oxford: Archaeopress. British Archaeological Reports, International Series, Vol. 667, pp. 217–218.Google Scholar
- Tsatskin, A., Weinstein-Evron, M., and Ronen, A., 1995. Weathering and pedogenesis of wind-blown sediments in the Mount Carmel caves, Israel. Quaternary Proceedings, 4, 83–93.Google Scholar
- Van Vliet-Lanoë, B., 1985. Frost effects in soils. In Boardman, J. (ed.), Soils and Quaternary Landscape Evolution. Chichester: Wiley, pp. 117–158.Google Scholar
- White, W. B., 2000. Development of speleogenetic ideas in the 20th century: the modern period: 1957 to the present. In Klimchouk, A. B., Ford, D. C., Palmer, A. N., and Dreybrodt, W. (eds.), Speleogenesis: Evolution of Karst Aquifers. Huntsville: National Speleological Society, pp. 39–43.Google Scholar
- White, W. B., and Culver, D. C., 2005. Cave, definition of. In Culver, D. C., and White, W. B. (eds.), Encyclopedia of Caves. Amsterdam: Elsevier, pp. 81–85.Google Scholar