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The Taurus Mountains, the most important karst terrains of Türkiye, contain many surface and subsurface karst landforms, and the morphometric features of these landforms provide important data on the geomorphological and morphotectonic development of karst areas in the Taurus Mountains. Micro and macro karst depressions are the most important surface landforms in the Western Taurus Mountains. In this study, a total of 7093 micro depressions (doline) and 74 macro depressions (polje) located in the Western Taurus Mountains were detected and morphometric properties were calculated. The poljes developed within the Beydağları Autochthon and Lycian nappes, while the dolines developed mainly in the high karst plateaus within the Beydağları Autochthon. As briefly described below, the morphotectonic evolution of both landforms is closely related to the tectonic evolution of the Western Taurus Mountains. As a result of this tectonic activity, the Lycian Nappes from the northwest and the Antalya Nappes from the east thrust over the Beydağları autochthon, leading to the development of nappes, reverse faults, and fold systems in the study area. The Western Taurus began terrestrialization starting from the Oligocene and began to erode from the Miocene. This erosion process led to the development of valley systems within the Western Taurus region. The NE–SW and NW–SE directional normal faults have developed under the influence of extensional tectonics since the Miocene. This extensional tectonism has caused widespread development of the poljes in the study area. Furthermore, with the lowering of the karst base level, dolines and paleovalleys began to develop in limestone areas at higher elevations. All morphometric and morphotectonic processes reveal that the extension of both doline and polje areas in the study area are parallel to the elongation of tectonic structures in the Western Taurus. [ABSTRACT FROM AUTHOR]

Dolines are the characteristic landforms in karstic landscapes, and their morphometric characteristics are commonly used for surface karst research. More than 140,000 dolines were identified using 1:25,000 scale topographic maps (TOPO-Maps) in the West and Central Taurus, Türkiye's most important karst terrain. However, the accuracy of these TOPO-Maps in terms of real morphometric characteristics of dolines in the Taurus Mountains is unknown. For this reason, in this study, dolines were automatically delineated from high-resolution digital elevation models (DEMs) produced by unmanned aerial vehicles (UAV-DEMs), and their morphometric characteristics were compared with the results obtained from 1:25,000 scale TOPO-Maps. UAV-DEMs with resolution below meter level provide a more accurate representation of the real Earth surface and thus landforms can be examined in more detail. In this study, six locations covering a total of 8.03 km2 were modeled with UAV. According to the results, the accuracy of the TOPO-Maps in terms of doline numbers was 0.24 (24%)–0.98 (98%), and this rate increased as the average area of the dolines increased. Doline density was always high with UAV-DEM data, and doline density had an average 99% increase when compared with TOPO-Map data. Due to UAV-DEMs providing the opportunity to calculate more morphometric characteristics, in this study, we provide information for the first time about the depth, slope, and volume characteristics of dolines in the Taurus Mountains. The mean depth, slope, and volume of solution dolines were 31 m, 45°, and 207,931 m3 in the Taurus Mountains, respectively. [ABSTRACT FROM AUTHOR]

Filling of dolines with aeolian sediments, one of the less frequently described ways in which they are filled, is analysed in the present study on an example of a doline in the high-mountain karst of the Dinarides. There is a series of deep dolines on a broad ridge (about 2450 m a.s.l.) on Mt. Durmitor (Montenegro) in the southeastern part of the Dinarides. The accumulation of very fine-grained sand that almost completely fills one of the dolines was analysed. More than 99% of the accumulation was found to be composed of well-sorted quartz grains with an average size of 89 µm and no vertical differences in granulometric or textural characteristics. With respect to mineral composition, the accumulation differs significantly from that prevalent in this part of the Dinarides, in which different kinds of carbonate rocks are dominant. The conducted analyses indicated an aeolian origin of the sediments. Significant aridification that began in the Middle Holocene made the area of North Africa a source of sediments that were transported by the aeolian process to neighbouring regions. Geomorphological-sedimentological research on Mt. Durmitor and earlier investigations of the wider Mediterranean region indicate that dolines in high-mountain karst can be filled with aeolian sediments. The sediments originated from territory of the northern Sahara, and the filling occurred in the Late Holocene, at the close of the African humid period. The present study shows that apart from the influence of local factors, regional geomorphological processes such as aeolian transport can also exert significant influence on the filling of dolines. It also indicates a high intensity and strongly expressed dynamics of aeolian sediment transport from the territory of Africa to this part of Southern Europe. [ABSTRACT FROM AUTHOR]

By the example of Tara National Park (NP), we present how the geoheritage can and should be presented in a NP where the primary role is played by biology. Tara NP has a rich geoheritage, especially its karst phenomena, which include gorges (e.g. the 1000-m-deep Drina Gorge), plateaus with dolines, dry valleys, and uvalas as well as springs and travertines. In addition, ophiolites also enrich the geoheritage; hence, the area has a high geodiversity. Large reservoirs of the territory provide an opportunity to study the anthropogenic impact on hydrology and geomorphology. After presenting the geoheritage elements of the area, we examine the views and knowledge of local people and visitors about karst and geotourism with the help of a questionnaire survey. The results show that local residents support the further development of tourism, but geotourism is a rather new concept for them. On the contrary, tourists are more familiar with geotourism. Among the development perspectives, tourists support those that involve only minor environmental changes, that is in agreement with NP policy. Finally, we formulate some suggestions about geotourism development in the area. First, we outline some plans for new geo-educational trails and viewpoints. Second, we highlight the possibility to increase the geo-content of some already existing programs (e.g. boat tours). Third, we emphasize that geotourism of Tara should be connected to neighbouring areas. A new geopark is already under planning, which would include the area of Tara NP as well. [ABSTRACT FROM AUTHOR]

Gypsiferous soils in karstic landscapes are important areas in terms of biodiversity and geology. One of the geological formations occurring in gypsum regions is the doline lakes. Subsidence dolines must be preserved because of their formation and fossil heritage. Erosion is one of the most serious types of degradation among these types of lakes. The Bakkal Lake is one of the most important doline lake in central Turkey and is at risks with sediment flow. In this study, we aimed to determine how erosion poses a threat to the geological heritage in areas such as doline lakes and to simulate what measures can be taken to protect them. RUSLE/GIS/remote-sensing technologies were used to estimate the distribution and amount of sediment flowing into the lake. According to the results of the study, the amount of sediment transported to the lake was estimated to be 2.73tha−1y−1, and the total amount of sediment transported was 2876 m3y−1. The time until Bakkal Lake is filled with sediment flux was calculated to be 698 years. The simulation was developed by offering protection measures to reduce sediment flow to the lake. As a result of the simulation, it was calculated that the amount of sediment flowing into the lake decreased to 2.29 tha−1y−1 and the filling time increased to 833 years. The study showed that a doline lake, which under natural processes would not be filled for thousands of years, will soon be filled unless radical measures are not taken. This study asserts that more planners should use simulations to model sediment flow to better select appropriate conservation measures. [ABSTRACT FROM AUTHOR]

The geomorphologic features called tiankengs were first discovered and named at the end of the twentieth century in karst areas of China. They have enjoyed increasing attention owing to their unusual geologic processes and unique ecological communities. However, the understanding of classification, geomorphic evolution, developmental conditions, geological dating and ecological environments of tiankengs are still extensively disputed by geomorphologists and geologists. This article focuses on combining all main areas of recent research activities from three aspects: development, evolution and transformation of karst tiankengs; biodiversity of karst tiankeng forests; and the impact of human activities on karst tiankeng ecosystems. Finally, we suggest future direction for research on karst tiankeng ecosystems: (1) multidisciplinary systematic study; (2) processes of ecological change and environmental effects under the influence of both natural and human impacts; (3) research on their protection, rational utilization, and sustainable management. [ABSTRACT FROM AUTHOR]

Gypsum covers an area of approximately 5 % in Turkey and is mainly found in Sivas basin. Gypsum in the Sivas basin includes many karst structures with various sizes and has a variety of forms that present different conditions offering different morphometric features. Two basic shapes of karstic terrain are reflected in this area offering a wide variety of gypsum karst. The first of these are dissolution dolines which constitute the polygonal karst areas, and the second one is collapse dolines which is deeper karst depressions formed by roof collapse and the accompanying of solutions. The aim of this study was to determine and identify general characteristics of doline in the study area using morphometric measurements and calculations. Density of dolin is very high in study area. The source of the dolines data included 1/25,000 scale digital maps containing elevation and several cartographic attribute interpretations, a very demanding field work and satellite images. The parameters calculated for the study area include depression length, width, orientation, area, perimeter, depth, circularity index, depression density, circularity index, length/width ratio and major axis orientation. This study describes an application of geographic information systems to examine the morphometric and geological features of gypsum karst in Sivas basin. The effect of geologic, structural, and hydrogeologic variables on the morphometry and spatial distribution of depressions are discussed in the study. [ABSTRACT FROM AUTHOR]

Globally, sinkholes cause hundreds of millions of dollars in damage and hundreds of deaths or injuries each year. To mitigate the damage caused by sinkholes, it is necessary to determine the susceptible or hazardous areas. The purpose of this study is to produce a sinkhole susceptibility map based on a logistic regression method within a geographic information system environment. A field survey for this investigation identified the locations of 182 sinkholes in the study area. Many geologic, geomorphologic, hydrogeological and anthropogenic factors that influence sinkhole development were identified in the Karapınar Region. In this study, 30 sinkhole-influencing factors were selected and used in the analysis. The coefficients of the predictor variables were estimated using binary logistic regression analysis and were used to calculate the sinkhole susceptibility for the entire study area. The area value of the receiver operating characteristics curve model was 0.814. The final map indicates that most of the observed sinkholes are predicted in the high or very high sinkhole susceptibility classes. These results indicate that this model is a good estimator of sinkhole susceptibility in the study area. The sinkhole susceptibility map shows that areas with no or very low, low, moderate, high and very high sinkhole susceptibility classes are 605 km (25.6 %), 310.8 km (13.1 %), 531.2 km (22.5 %), 487.7 km (20.6 %), and 429.0 km (18.1 %), respectively. Interpretation of the susceptibility map shows that sinkhole formation decreased with increasing slope angle, cover thickness, electrical conductivity, and the concentration of calcium, magnesium, sodium, and potassium ions in groundwater. However sinkhole formation increased with drainage density, fault density, upper levels of karstic formations, decline in groundwater level, and well density. This map will serve to help citizens, urban planners and design engineers prevent damage caused by existing sinkholes as well as sinkholes that develop in the future. [ABSTRACT FROM AUTHOR]

This study presented a quantitative comparison of cockpit and doline karst by examining the numbers and characteristics of typical types of landform entities that are developed in Guilin (Guangxi, China), La Alianza (PR, USA), Avalton (KY, USA), and Oolitic (IN, USA). Five types of landform entities were defined: isolated hill (IH), clustered hills (CHs), isolated sinkhole (IS), clustered sinkholes (CSs), and clustered hills with sinkholes (CHSs). An algorithm was developed to automatically identify these types of landform entities by examining the contour lines on topographic maps of two cockpit karst areas (Guilin and La Alianza) and two doline karst areas (Oolitic and Avalton). Within each specific study area, the CHSs is the least developed type yet with a larger size and higher relief. The IH and IS entities are smaller in size, lower in relief, and outnumber their clustered counterparts. The total numbers of these types of entities are quite different in cockpit and doline karst areas. Doline karst is characterized by more negative (IS and CSs) than positive (IH and IHs) landforms and vice versa for cockpit karst. For example, the Guilin study area has 1192 positive landform entities in total, which occupy 9.81% of the total study area. It has only 622 negative landform entities occupying only 3.91% of the total study area. By contrast, the doline karst in Oolitic has 130 negative while only 10 positive landform entities. The positive and negative landforms in Oolitic occupy 12.68% and 2.61% of the total study area, respectively. Furthermore, average relief and slope of the landform entities are much higher and steeper in the cockpit karst than the doline karst areas. For instance, the average slope of CHs in Alvaton is 3.90 degrees while it is 19.78 degrees in La Alianza. The average relief of CSs is 4.07 m and 34.29 m in Oolitic and Guilin respectively. Such a difference within a specific area or between the cockpit and doline karst may reveal different controls on the development of karst landscape. [ABSTRACT FROM AUTHOR]

This work describes karst landforms observed in the northern Sinus Meridiani region located between 1°18′N to 2°30′N latitude and 2°30′W to 0°13′W longitude, which covers approximately 9,100 square kilometres, characterized by spectral signatures of evaporite minerals. An integrated analysis of the Reconnaissance Orbiter (MRO) High Resolution Imaging Science Experiment (HiRISE), High Resolution Stereo Camera (HRSC), and Mars Orbiter Camera (MOC) imagery were used to perform a morphological and morphometric investigation of the study area. Results resolved three specific morpho-units, characterized by different doline features, which displayed distinct types and degrees of karstification in the study area. The landforms indicated different solutional properties of the units, and suggested enough liquid water in the recent past was present to form the karst landforms, emphasizing climatic changes during the Amazonian period occurred in the Sinus Meridiani area. [ABSTRACT FROM AUTHOR]

The valleys within the Appalachian Mountains are often floored by carbonates. When remediating or preventing sinkhole activity in any karst, consideration should be given to a number of geologic, geotechnical and environmental concerns. Primarily, one must recognize that Appalachian karst is most likely variably faulted and folded and cannot be evaluated in the same manner as the flat-lying carbonates of the mid-continental US or the lightly cemented, recent karst of Florida. Also, in the tectonically abused rocks of the northeastern US, with their resultant solutioned discontinuities, one must also recognize the possible effects that glaciation may have had in the more northerly portions of the region. Investigative tools that can aid in deciphering these considerations include aerial imagery, review of sinkhole maps, geologic reconnaissance, test pits, test borings and percussion probes. In the authors' experience geophysics, unless combined with hard data, rarely provides useful geotechnical information even when costly programs are performed by competent individuals. Depending upon the nature of the sinkhole/doline and its effects upon man-made and natural environments, a number of effective remedial measures are available. This paper briefly addresses these various types of remediation including high and low mobility grouting, drainage maintenance, dynamic compaction (destruction) and structural solutions in relation to the encountered conditions, with consideration for economics, and will present case histories illustrating a number of problems and solutions in discussion. [ABSTRACT FROM AUTHOR]

Karst topography is a landscape shaped by the dissolution of a layer or layers of soluble bedrock, usually limestone and evaporites. Karstification in the Sivas basin (Turkey) has sculpted a beautiful landscape with a distinctive beauty and appeal for both local inhabitants and visitors. Dolines are very special geological landscape features found in karst regions, and the Sivas basin has several giant dolines amongst its thousands of smaller dolines. The basin constitutes a distinctive karst architecture with a system of collapse and/or dolines and caves. Anyone who walks along the shores of a lake resulting from the collapse, in this gypsum terrain, will be amazed with the lake and rocks that surround them. In this paper, dolines in the gypsum terrain are evaluated and discussed according to their value as a 'Geological Heritage'. Three main characteristics of dolines, namely their scientific, aesthetic and ecosystem importance are considered and discussed. Dolines and karstified areas as representative examples of landform types possess the three attributes for them to be considered as a Geological Heritage in that they demonstrate the effect of erosion on the landform, geomorphic processes that are still active and a range of features characteristic of the rock unit involved. [ABSTRACT FROM AUTHOR]

Ground penetrating radar (GPR) has been applied, with relative success, to locate paleo-collapses and cavities and to detect and characterise karst. One of its main advantages is that, while the penetration depth is limited to several tens of meters or even just several meters, the obtained resolution can be in the scale of centimeters. In this paper, we illustrate the applicability of GPR prospecting to the study of alluvial karst and the structures associated with subsidence areas. GPR radargrams obtained with two central frequency antennas (50 and 100 MHz) are balanced against direct observation of geological features of collapse structures in vertical exposures of gravel quarries. GPR-surveys offer the possibility of obtaining nearly continuous vertical cross-sections of the subsoil, and integration of data within a 3D frame. However, the study of the internal structure of the subsoil by means of the GPR-profiles has been usually neglected. In this work, we show that some hints about the evolution of individual dolines can be established from the study of the geometry of the sedimentary filling by means of GPR. The obtained results indicate that GPR allows to characterise the structures associated with karst features and can therefore be useful evaluating hazard susceptibility in doline fields, because: (1) when no surface evidences exists, it permits the detection of karst hazards in the subsoil, and (2) when surficial evidences of karst activity are present, it permits the characterisation of processes associated with subsidence. [ABSTRACT FROM AUTHOR]

Texture and grain size is of great importance in understanding the mechanical properties of rocks. The aim of this study was to investigate textural and slaking durability characteristics, and correlate them with the gypsum types where the dolines occurred, with particular reference to the texture and crystal size. The investigation comprised two stages: field work and laboratory testing. Initially, rock samples were obtained from various representative karstified and non-karstified locations. Thereafter, mineralogical, physical and slaking durability characteristics of the gypsum samples were determined by means of laboratory testing. After the field and laboratory works, the geological, mineralogical and slaking durability characteristics of the study area gypsum were reviewed and discussed from the point of view of doline formation. Results showed that fine grain sized alabastrine gypsum tends to be karstified and leads to doline formation. This is closely related to the crystal size, texture and attributable to the slaking durability of the gypsum. Consequently, the results demonstrate that the texture, especially crystal size, and effective porosity are important parameters controlling the slake durability of the gypsum and doline formation. [ABSTRACT FROM AUTHOR]