6.10 Classification of Closed Depressions in Carbonate Karst

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1 6.10 Classification of Closed Depressions in Carbonate Karst A Kranjc, ZRC SAZU, Postojna, Slovenia r 2013 Elsevier Inc. All rights reserved Introduction Doline Solution Doline Cockpit Collapse Doline Caprock Doline Subsidence (Suffosion/Dropout) Doline Buried Doline Uvala Polje 109 References 110 Glossary Bogaz (or karst corridor, karst ditch, a corridor or a passage) A street through giant grikes or stone forests and tsingies of the karst in tropical countries. In Turkish language it means a narrow passage. It entered the karst terminology from the karst of Balkans. Cenote Collapsed doline or vertical entrance of a cave, permanently filled with water, a sort of a window to the karst groundwater level. It is a typical feature of shallow (above the groundwater level) karst, such as on Yucatan peninsula. The name has the origin in the language of Maya Indians, that is the 16th century term of Yucatan Maya dzonot meaning mirror of water, hispanized in cenote. Collapse Sudden subsidence of the surface, usually the breakdown of blocks of the rock (often from the cave ceiling) or a part or entire ceiling of the cave. Corrosion In karstological terminology it means dissolution of carbonate rock. From the rock, water changes calcium carbonate, CaCO 3, into calcium bicarbonate Ca(HCO 3 ) 2, which is soluble in water and transported away by the running water. Water which contains CO 2 is more aggressive and can dissolve more calcium carbonate. Water can be enriched by CO 2 mostly when percolating through soil or decaying organic material. Diffuse drainage Autogenic recharge, diffuse infiltration, is the condition whereby precipitation infiltrates into the karstic aquifer via many openings in the bedrock thus allowing approximately uniform amounts of recharge per unit area of aquifer outcrop. Therefore there are no surface streams or surface drainage. Opposite of this is concentrated drainage, point recharge, or allogenic recharge. Holokarst Fully developed karst on pure limestone, including both surface and underground karst phenomena. The term was introduced by J. Cvijić. Opposite to holokarst is just partly developed merokarst. Ponor (swallow hole, sinkhole, sink) Point where surface stream sinks into the karst underground. Often the ponor means a cave, where an entire stream flows underground. The term has origin in Serbian language. Abstract Closed depressions are the most characteristic features of karst having dolines among them. Some of the terms, such as doline, uvala, and polje, originate from the Dinaric karst, internationally introduced by J. Cvijić in Karst depressions belong to mezo- and macroforms (from decameter to kilometer scale). The basic feature is the doline, which can be further divided due to its genesis into more main types: solution (the real karst doline), collapse, dropout, buried, caprock, and suffosion doline. The larger depressions, by dimension and form somewhere between a doline and a polje, are the uvala, but genetically they are closer to the doline. Polje (meaning a plain or field in Slavic languages) is the biggest closed depression, its bottom covering several hundreds of square kilometers. Closed depressions, solution dolines and poljes especially, are regarded as indicators of a fully developed karst (holokarst by Cvijić) Introduction Kranjc, A., Classification of closed depressions in carbonate karst. In: Shroder, J. (Editor in Chief), Frumkin, A. (Ed.), Treatise on Geomorphology. Academic Press, San Diego, CA, vol. 6, Karst Geomorphology, pp Closed depressions are characteristic features of karst. Some karst regions occur without them, but these are exceptions. Taking into consideration the process of karstification and the diffuse drainage directly into the karst underground, their 104 Treatise on Geomorphology, Volume 6

2 Classification of Closed Depressions in Carbonate Karst 105 appearance on the surface is normal. Rainfall on soluble and fissured carbonate rock sinks immediately underground and commonly there is no surface runoff. Water corrodes the rock, and initial depressions begin to form. While growing they attract more and more water, corrosion is more intensive, and depressions become bigger. The difference between the initial depression and the neighbor surface is even greater, the depression deepening is accelerated, and the adjacent surface lags behind. In Slovenia, at the time when the notion of karst was not yet known to scholars, closed depressions were well noticed by Valvasor already in The first researchers, in the modern sense of the word, noticed that closed depressions are typical forms of karst and paid special attention to them. In 1778, B. Hacquet described dolines using the German word Kessel (¼ kettle), and for polje he used the word Kesseltal (¼ kettle valley). The term already indicates the stress on a closed form (Kranjc, 2003). In the first half of the nineteenth century, the first modern geological research of karst started in what is nowadays Slovenia. The authors mentioned funnel shaped deepening, called dolina by the local people. In 1847, a certain Rosthorn reported to Vienna learned society that he has investigated 1000 dolines. In Bosnia and Herzegovina, where poljes are the main karst feature, Austrian geologists started geological research at the end of the nineteenth century and introduced the term polje. J. Cvijić s fundamental work Das Karstphänomen (1893), that is, the phenomenon of karst was probably the decisive work for the introduction of the terms doline, uvala, and polje into the international karstological terminology (Kranjc, 2009) Doline A doline is perhaps the most characteristic karst feature (Cvijić, 1893), at least among those of exclusively corrosion origin. They are especially common on a mature developed karst of young folded mountains such as the Dinaric karst (Figure 1) and similar types of karst. A doline is a natural enclosed depression. It is usually circular or subcircular in plan and from a few to a thousand meters in diameter. The depth can vary from a few to a few tens of meters, Figure 1 A rock terrace with dolines above the bottom of Grahovo Polje (Bosnia). Photo A. Kranjc. exceptionally to a few hundreds. The sides can be from gently sloping to vertical, and their form can range from saucer shaped to funnel shaped or even cylindrical. Enclosed depressions in karst including dolines may be formed by four main mechanisms: dissolution, collapse, suffosion, and regional subsidence. Some authors classify dolines according to their shape (Gams, 2004), whereas others by their origin. Slovene karst terminology includes 14 types of dolines. In Panoš s (2001) Karst and Speleology Terminology, there are 35 types of dolines, according to their evolution stage, genetic process, type of sediment cover, climatic factor, internal deposits, and shape. But among them are forms that can be classed as other forms, not dolines. Such examples are bogaz, cenotes, and bell-shaped doline, the last is, in fact, a shaft. Williams (2004) quoted nomenclature of six main types of dolines by seven well-known authors; all agree with two types: solution and collapse doline, yet they have different opinions and names for other types. Largely agreed upon are six types of dolines (Waltham and Fookes, 2003): solution doline, collapse doline, dropout doline, buried doline, caprock doline, and suffosion doline (Figure 2) Solution Doline The main process involved in the genesis and evolution of a solution doline is dissolution or corrosion of the bedrock. The amount of a rock removed in solution depends on the concentration of the solute and on the volume of the solvent (water draining through the doline). The development of a doline depends on the ability of water to sink into and flow through karst rocks to an outlet spring. On bare limestone (referred to as a bare karst), the recharge is diffuse (autogenic recharge) and the rainwater directly corrodes the limestone. The corrosion by atmospheric water is most intensive through the upper few meters of the limestone (epikarst or subcutaneous zone) (see Chapter 6.15). Joints, faults, and bedding planes are discontinuities where the water enters the rock. In areas with high fissure frequency, there are more and smaller dolines, whereas particularly large dolines develop in massive, less fissured rocks (Williams, 2004). The distribution of dolines depends strongly on the tectonic structure. Alignment of dolines (Figure 3) shows that they evolved along a tectonic line. The density of dolines can vary considerably, also in accordance with their dimensions. The highest density of dolines can reach hundreds and even 1000 per km 2, where the whole surface (see Chapter 6.33) is represented by dolines. Therefore, it is not surprising that dolines can reach very high numbers from a regional point of view; on the karst of Croatia, for example, 350,000 dolines were digitized (Kranjc, 2009: 170; Matas, 2009). The bottom of a doline is commonly covered by a finegrained sediment, the nonsoluble detritus of the dissolved limestone, or derived from other fine materials in the surroundings, by local washout of soil or loose sediment, or wind deposits. It may be transformed into red karst soil, from terra rossa in humid and warm climates to carbonate brown soil on the karst in more temperate and cooler climates. This is the reason why commonly only the bottoms of dolines can be cultivated on karst. On the plateau of Kras (Slovenia, where

3 106 Classification of Closed Depressions in Carbonate Karst Solution doline Collapse doline Dropout doline Fissure enlargement Surface corrosion Minor collapse Fallen blocks Cohesive soil Collapsed soil Cave or fissure Cave Cave Fissure or cave Buried doline Possible compaction depression Caprock doline Stoping collapse Suffosion doline Soil Caprock Noncohesive soil Soil washing into fissure Cave Caves and fissures Cave Fissure or cave Figure 2 Six main types of dolines. Reproduced from Waltham, A.C., Fookes, P.G., Engineering classification of karst ground conditions. Quarterly Journal of Engineering Geology and Hydrogeology 36, Figure 3 A line of solution dolines in Dinaric karst (Southern Velebit Mt., Croatia). Photo A. Kranjc. the term karst came from), people buried the stones derived by cleaning the slopes of dolines into their bottoms, scraped the soil from the slopes and from the neighboring surfaces, and spread it over the bottom. In this way, the flat bottom of the doline becomes larger and becomes thicker soil. In the local language, such a doline is called man-made doline (Figure 4) (Gams, 2004). Due to the fact that dolines are closed, they may have a specific micro-climate with temperature inversion. In some cases of very big and deep dolines, this inversion is expressed in a vegetation inversion too (Bárány- Kevei, 1998). The inhabitants of the Kras plateau call a doline, dolina and variants such as dol and dolec. In Slovene, as in many other Slavic languages, a dolina simply means a valley. In the Figure 4 An example of a man-made doline (under Dinara Mt., Bosnia) man gathered loose rocks and buried them in the bottom of doline, scraped soil from the slopes, and spread it over to get more surface for cultivation. Photo A. Kranjc. middle of the nineteenth century when geologists started modern research on karst in Kranjska (Carniola, Slovenia), one of the Austrian hereditary countries, they soon perceived that dolines are a special form of limestone landscape. This funnel-shaped (Trichterförmige in German) depressions they called a funnel (Trichter), but often they simply used the local term, doline. Gradually, the word doline (plural form of dolina) became the term for collapsed dolines (steep or precipitous) and for the normal (corrosive, solution) dolines they took the term Trichter (a funnel). In Cvijić s highly influential work Das Karstphänomen (1893), there is a separate chapter titled Dolinen, where he treats not only dolines but also all

4 Classification of Closed Depressions in Carbonate Karst 107 sorts of closed depressions including some karst springs, with the exception of uvalas and poljes. He decided to use the term doline after the name of small hollows in the part of Carniola, between Ljubljana and Planina especially. In international use, doline means primarily solution doline, while the other main type is called collapsed doline. The term sinkhole entered into international use from America. Basically, it means sinkhole, swallow hole, and ponor (see Chapter 6.11), where the water sinks underground. Sometimes, the term is used to refer both to dolines and to depressions with ponor. In America, it means a special type of collapse doline, similar to suffosion or dropout doline, where the sudden collapse can cause a great damage. Thus, the terms sinkhole and doline are not strictly synonymous (Williams, 2004). One of the first books on karst in Slovene language, Geography from 1874, does not use the term doline but instead, the term sinkhole. To avoid confusion with the fluvial valley, Slovene geographers very early (1908, 1913) used the term vrtača, which was later proposed by Cvijić to be used in the Serbian language. After World War II, Slovene karstologists stopped using the term doline completely. The same happened in other Slavic languages; they do not use the term dolina, but an appropriate expression in their language (Kranjc, 2009) Cockpit Cockpit karst is a karst terrain in a warm and humid belt dotted with big solution dolines cockpits, as they are called in Jamaica. The rims of these big dolines touch; the available space is occupied by depressions (Figure 5). The solutions dolines cockpits are approximately star-shaped in form and are separated by irregular ridges and hills in the shape of cones, so a synonym of cockpit karst is cone karst. Topographic divides of the dolines have a polygonal pattern and such karst is also called polygonal karst (Williams, 2004). Commonly, a cockpit is a synonym for tropical doline. In Figure 5 Large cockpit in tropical karst (Leye Co., Guangxi province, China). Photo A. Kranjc. general, the cockpit doline is greater than normal solution doline (in temperate karst) with secondary fluvial relief (small ravines of streams after heavy rains, draining into ponors in the bottom). Thus, a great number of these dolines cockpits are by some properties closer to an uvala than to a solution doline Collapse Doline A collapse doline is formed mainly by collapse, that is, rapid downward movement of the ground. The role of solution is indirect by enlarging the cave under the surface, to lower the surface, to enlarge the fissures to a point where the ceiling is too weak and breaks collapses, and a collapse doline is formed (Williams, 2004). It is preferentially subcircular in plan, commonly between a few tens to a few hundred meters in diameter, with very steep to vertical or subvertical slopes. Its width is bigger than its depth; otherwise, it is termed a karst shaft. Over time, the sides of a collapse doline degrade mostly by weathering. The slopes become less and less steep, and debris infills the bottom, which flattens. By this time, a collapse doline loses its typical form and becomes similar to a big, bowl-shaped solution doline. The biggest collapse dolines have a volume of tens of millions of cubic meters. One of the reasons of the collapse is thinning of the cave ceiling of large caves. The process of the thinning is not only corrosion and subaerial denudation, but also breaking down of the rocks from the cave ceiling. Big cave chambers (commonly referred to as a breakdown chamber) with relatively thin ceiling may be situated at the edge of karst plateaus, in the hinterland of karst springs or ponors, and these are places where collapse dolines are commonly situated. A good example is Škocjanske Jame (Slovenia) listed in the UNESCO World Natural Heritage (United Nations Educational, Scientific and Cultural Organization, UNESCO). If the bottom of a collapse doline reaches the karst groundwater table (or the level of the water table changes) the bottom of such collapse dolines can be periodically or permanently flooded. In such a case, the problem can be how to distinguish without detailed studies a collapse doline from a cenote or a blue hole, if a collapse doline is submerged by the sea. A closed depression which is deeper than larger is defined as a speleological object. Therefore, depending on their depth/ width ratio, some cenotes can be classified as speleological objects while others are surface features dolines. In the professional literature, cenotes belong either to the surface forms dolines (Panoš, 2001), or to subterranean forms caves (Gunn, 2004). An illustrative example is Crveno Jezero (Figure 6), a collapse doline, or vertical cave, in Dalmatia (Dinaric karst). The diameter is about 300 m, the depth is 528 m with the bottom 6 m under the sea level. The lower part of the doline (about 280 m deep) is filled by water the lake (Garašić, 2000). Due to their large size and form, collapse dolines are outstanding surface features and therefore easily noted in the field. This is why people commonly refer to them with special local terms. In Slovenia, there are nearly 10 local expressions for collapse dolines and commonly each collapse doline has a

5 108 Classification of Closed Depressions in Carbonate Karst Figure 7 Xiaozhai Tiankeng (Chongqing Municipality, South China), 662 m deep collapse doline with a volume of million m 3. Photo A. Kranjc. visible part of the doline, is in noncarbonate rock and also the debris at the bottom is of the same rock Subsidence (Suffosion/Dropout) Doline Figure 6 Crveno Jezero (Red Lake) collapse doline above the Imotsko Polje (Croatia), more than 500 m deep and half under water. Photo A. Kranjc. special name too. The biggest known collapse doline on the Kras plateau has a volume of 11 million m 3 (Kranjc, 2005). Whereas, on the high karst plateaus of southeastern Asia, well surveyed especially in China, extremely large and deep collapse dolines developed. They are over 500 m deep and their volume exceeds 100 million m 3. Locally they are called tiankeng (tian ¼ sky, nature, keng ¼ hole). Among the karstologists there is a tendency to include tiankeng in the international karst terminology. The biggest known is Xiaozhai Tiankeng (Figure 7) (Xinlong karst in South China), 662 m deep with a volume of million m 3 (Zhu and Chen, 2005). In most cases, an underground river is flowing at the bottom of a tiankeng Caprock Doline It can be said that a caprock doline is a subtype of a collapse doline. The general process is the same as with a collapse doline. A void in limestone grows, its ceiling becomes too thin or too weak, and it collapses. But in the case of a caprock doline, the carbonate rock is covered by a layer of noncarbonate rock caprock. The upper part, often the only A subsidence doline is a closed surface depression in the form of a solution doline, but in a sediment cover of carbonate rock. It is developed by evacuation (suffosion) of sediment cover downward into a karst void underneath. The result is rapid or gradual subsidence of the surface. According to the type of subsidence, the subsidence dolines are divided into two types: the dropout and the suffosion dolines. In cohesive sediment, the subsidence is often sudden and the result can be catastrophic. This type of a doline is called a dropout doline. In noncohesive sediment, most commonly soil, the clayey fraction tends to move as slurry into the cavity underneath, whereas the coarser fraction remains nearer to the surface. Such a type of doline is called a suffosion doline (Figure 8) and it is usually of relatively small dimensions, in the meter scale (Williams, 2004) Buried Doline This is a normal solution doline filled with sediment. On the surface, there is no evidence that in the bedrock there is a closed depression buried solution doline. They can be located by earth excavation or by geophysical or geotechnical survey. Sediment in such dolines can be of economic value, such as bauxites (Williams, 2004). Good examples are big buried dolines of the Ravni Kotari (¼ flat region) corrosion plain along the Dinaric coast of the Adriatic Sea. They are filled by bauxite and covered by large conglomerate covers of Tertiary (Jelar) formation Uvala According to the Slovene karst terminology (Gams, 1973), an uvala is a closed depression of a bowl shape on a karst surface, usually smaller than a polje and greater than a doline with

6 Classification of Closed Depressions in Carbonate Karst 109 Figure 8 Suffosion type of subsidence doline on the Ice Mt. above the town of Kungur (Permski krai, Russia) in the Pre-Ural evaporite karst. Photo A. Kranjc. irregular bottom due to incorporated dolines. Regarding its form, it is also between the polje and a doline. The term was introduced from the Serbian language (it means a valley, a gap between two mountains) by Cvijić in His definition is as follows: Uvala is a karst depression, bigger than doline, few 100 m long, sometimes even 2-3 km. As a rule there are dolines in its bottom. The brinks of those dolines are lower than the brink of the uvala (Cvijić, 1926). The rim of an uvala is irregular in general; the bottom is bare or covered by soil or sediment. Uvala is an international term despite the tendency to abandon it. According to Cvijić, an uvala is formed by solution through the coalescence of dolines into a bigger depression. Further evolution leads to a polje by the coalescence of uvalas. Some authors do not agree that uvalas are formed exclusively by the corrosion of limestone and it is mostly agreed that they are not formed by the coalescence of dolines. Although an uvala is not an entry in Gunn s (2004) encyclopedia, the author of a chapter on dolines, P. Williams, mentions it. He even states that Individual dolines may merge to form compound closed depressions (known as uvalas)y. A similar nonagreement regards the further evolution towards a polje by the coalescence of uvalas. Panoš (2001) stressed that uvalas are features of covered karst. According to his definition, the bottom of an uvala can be flooded sometimes or even contain a permanent lake. Considering the prevailing process, uvalas can be classified among dolines. Because the genesis is not clear and the researchers do not agree upon this question, it has been proposed not to use this term any more (Lowe and Waltham, 1995; Palmer, 2007). Some authors use the term strictly in a morphological sense: if it is neither a doline nor a polje, it has to be an uvala. In some cases, it is difficult to distinguish between a big atypical doline or an uvala, as well as between uvalas and atypical small poljes. Uvala can be either very deep, on high karst plateaus especially, with temperature and vegetation inversion, or having a low rim difficult to perceive. Uvalas are typical features of Dinaric types of karst (Figure 9). In tropical karst, the equivalent of uvala is a glade. The term comes from Jamaica and means closed depression like an uvala with wet grassland or marsh at the bottom (Sweeting, 1972). The last detailed Figure 9 Loški Potok, an uvala large enough for a village and fields (Dinaric karst, Slovenia). Photo A. Kranjc. study of the uvala question shows that it would not be wise to abandon the term, because there are distinct closed depressions that are neither dolines nor poljes and have quite clear common characteristics Polje Polje (see Chapter 6.11) is the largest flat-floored closed karst depression, typical especially for some types of well-developed karst in young folded mountain systems, such as the Dinaric karst, karst in Epirus, Peloponnesus, Taurus, Zagros, etc., or in karst that is called by Cvijić holokarst or fully developed mature karst. The surface of the polje s bottom can range from a few km 2 to 4500 km 2. It is suggested that the short axis of a polje bottom should not be shorter than 400 m (Gams, 1978). The biggest polje of the Dinaric karst, Ličko Polje, covers nearly 500 km 2 (Ford and Williams, 1989). A polje commonly has a noninterrupted rim. It can also be incompletely closed, with its rim open due to different reasons, such as a surface river flowing out; such a polje is called an open polje. A polje has to have a relatively large and flat bottom (Figure 10). The reason for levelness may be the sediment cover over relatively rough bedrock. The drainage from the polje is a part of the regional karst hydrology. From a regional point of view, the location of a polje is strongly connected to the tectonic structure. In the Slovenian Dinaric karst, for example, five poljes are located along the regional (160 km long) fault line. The great majority of poljes in the Dinaric karst has a Dinaric orientation, meaning that their long axis is oriented from NW to SE. This is the direction of general tectonic structures, which is also the direction of major morphological units. Poljes are polygenetic; they are the combination of different processes. Tectonically, predisposition is of primordial importance, not only for the location, but also for their main properties. In principle, polje is a karst phenomenon on carbonate terrain; however, due to the large dimensions, other rocks may be included, either as a part of polje s margin or as a part of its bottom. If the formation of the main depression is initially the work of tectonic forces or water, either through erosion or through corrosion, still

7 110 Classification of Closed Depressions in Carbonate Karst Figure 10 Cerkniško Polje (Dinaric karst, Slovenia) one of the best examples and the earliest-studied polje. Photo A. Kranjc. flooded, but otherwise it is dry. By the dimensions, turloughs may range from doline to polje, but their hydrological characteristics justify calling them by a special name. Recent research shows that such features are not restricted to the karst of Ireland but occur elsewhere too (Skeffington and Scott, 2008). The international term polje originated in the karst of Bosnia and Herzegovina, where they are the main karst feature. Austrian geologists started to study Bosnian and Herzegovinian karst, a part of Dinaric karst, in the second half of the nineteenth century and introduced in their published works the term polje. Finally, the term became international through the works of J. Cvijić. In Bosnian as well as in other languages of Southern Slavs, the word polje means plain, often cultivated, and even field. In Slavic languages, the original meaning of the word is something large, wide, and broad. Local people called a polje the large flat surface of the polje bottom, which can be cultivated, in contrast with polje s slopes and surrounding dry, bare, limestone landscape. In most of the Slavic karst terminologies, the adjective karst is added to the term polje: karst polje, not to be confused with another meaning of the word. References Figure 11 Turlough dry lake in the karst of Ireland (Castlerea, Roscommon Co.). Photo A. Kranjc. remains a matter of discussion. They can even differ from one example to another. Very few poljes correspond to all criteria of the polje definition. Because of their complex origin and evolution, there are many classifications of poljes according to different criteria, such as geological, morphological, and hydrological characteristics. The most complex overview of types of poljes is given in Panoš s (2001) terminology, where, according to different authors, 46 types of poljes are classified by geological structural position, origin, position on carbonate/noncarbonate rocks, macro-relief, hydrogeology, climate, ground plan, and cross section. Gams (2004) classification consists of five types based on lithological, morphological, and hydrogeological conditions: border, peripheral, kettle form, piedmont polje, and polje in the karst water table level. On the other hand, Ford and Williams (1989) proposed three main types only: border, structural, and base-level polje. Closed depressions called turlough (Figure 11), known from Ireland, may be included under the term polje. The word turlough means dry lake in the Irish language. Turloughs are closed depressions generally but not necessarily smaller than polje with flat bottoms and relatively low, not always well noticeable, margins. During the rain period, the bottom is Bárány-Kevei, I., Geological system of karsts. Acta Carsologica 27(1), Cvijić, J., Das Karstphänomen. Versuch einer morphologischen Monographie. Geographische Abhandlungen (Penck), (B), 5/3. Wien, E. Hölzel, Stuttgart, 114 pp. Cvijić, J., Geomorfologija, 2. Srpska akademija nauka i umetnosti, Beograd. Ford, D., Williams, P., Karst Hydrogeology and Geomorphology. Chapman and Hall, London, 601 pp. Gams, I., Slovenska Kraška Terminologija. Katedra za fizično geografijo FF, Ljubljana, 75 pp. Gams, I., The polje: the problem of definition. Zeitscbrift für Geomorphologie N.F. 22(2), Gams, I., Kras v Sloveniji v Prostoru in Času. Založba ZRC, Ljubljana, 515 pp. Garašić, M., Speleohydrogeological Research of Crveno jezero (Red Lake) near Imotski in Dinaric Karst Area (Croatia). Proceedings of the second Croatian Geological Congress. Cavtat-Dubrovnik, Croatia, pp Gunn, J. (Ed.), Encyclopedia of Caves and Karst Science. Fitzroy Dearborn, New York, NY and London, VII XVIII, 902 pp. Kranjc, A., Balthasar Hacquet, predecessor of modern karstology. Hacquetia 2/2, Kranjc, A., Some large dolines in the Dinaric karst. Cave and Karst Science 32(2&3), Kranjc, A., An example of karst terminology evolution: from Dolina to Tiankeng. Carsologica Sinica 28(2), Lowe, D.J., Waltham, T., A Dictionary of Karst and Caves. Cave Studies Series 8. BCRA, London, 40 pp. Matas, M., Krš Hrvatske, Geografski pregled i značenje. Geografsko društvo, Split, 264 pp. Palmer, A., Cave Geology. Cave Books, St. Louis, MO, 454 pp. Panoš, V., Karsologická a speleologická terminologie. Knižné centrum, Žilina, 352 pp. Skeffington, M.S., Scott, N.E., Do turloughs occur in Slovenia? Acta Carsologica 37(2 3), Sweeting, M.M., Karst Landforms. Basingstoke, London, 362 pp. Waltham, A.C., Fookes, P.G., Engineering classification of karst ground conditions. Quarterly Journal of Engineering Geology and Hydrogeology 36, Williams, P., Dolines. In: Gunn J. (Ed.), Encyclopedia of Caves and Karst Science. Fitzroy Dearborn, New York, NY, and London, pp Zhu, X., Chen, W., Tiankengs in the karst of China. Cave and Karst Science 32(2&3),

8 Classification of Closed Depressions in Carbonate Karst 111 Biographical Sketch Born 1943 in Ljubljana (Slovenia), Andrej Kranjc studied geography and archaeology; in 1972, he did an advanced study course of speleology in France; in 1977, he completed his master s degree; and, in 1986, he received his doctor s degree at Ljubljana University. He is a retired scientific adviser at the Karst Research Institute (Postojna), Scientific Research Centre of the Slovenian Academy of Sciences and Arts, Professor Emeritus and Head of the doctoral programme Karstology at the University of Nova Gorica, and a member of the Slovenian Academy of Sciences and Arts. He is a member of different boards of professional institutions and of editorial boards. As an expert, he visited karst all over the world. Among other awards, he is also a French Chevalier dans l Ordre des Palmes Académiques.