Karst and Cave RSS news feed Like us on Facebook! follow us on Twitter!
Community news

Speleology in Kazakhstan

Shakalov on 04 Jul, 2018
Hello everyone!   I pleased to invite you to the official site of Central Asian Karstic-Speleological commission ("Kaspeko")   There, we regularly publish reports about our expeditions, articles and reports on speleotopics, lecture course for instructors, photos etc. ...

Speleology in Kazakhstan

Shakalov on 04 Jul, 2018
Hello everyone!   I pleased to invite you to the official site of Central Asian Karstic-Speleological commission ("Kaspeko")   There, we regularly publish reports about our expeditions, articles and reports on speleotopics, lecture course for instructors, photos etc. ...

Speleology in Kazakhstan

Shakalov on 11 Jul, 2012
Hello everyone!   I pleased to invite you to the official site of Central Asian Karstic-Speleological commission ("Kaspeko")   There, we regularly publish reports about our expeditions, articles and reports on speleotopics, lecture course for instructors, photos etc. ...

New publications on hypogene speleogenesis

Klimchouk on 26 Mar, 2012
Dear Colleagues, This is to draw your attention to several recent publications added to KarstBase, relevant to hypogenic karst/speleogenesis: Corrosion of limestone tablets in sulfidic ground-water: measurements and speleogenetic implications Galdenzi,

The deepest terrestrial animal

Klimchouk on 23 Feb, 2012
A recent publication of Spanish researchers describes the biology of Krubera Cave, including the deepest terrestrial animal ever found: Jordana, Rafael; Baquero, Enrique; Reboleira, Sofía and Sendra, Alberto. ...

Caves - landscapes without light

akop on 05 Feb, 2012
Exhibition dedicated to caves is taking place in the Vienna Natural History Museum   The exhibition at the Natural History Museum presents the surprising variety of caves and cave formations such as stalactites and various crystals. ...

Did you know?

That saturated zone is see phreatic zone and zone of saturation.?

Checkout all 2699 terms in the KarstBase Glossary of Karst and Cave Terms

What is Karstbase?

Search KARSTBASE:

keyword
author

Browse Speleogenesis Issues:

KarstBase a bibliography database in karst and cave science.

Featured articles from Cave & Karst Science Journals
Chemistry and Karst, White, William B.
See all featured articles
Featured articles from other Geoscience Journals
Karst environment, Culver D.C.
Mushroom Speleothems: Stromatolites That Formed in the Absence of Phototrophs, Bontognali, Tomaso R.R.; D’Angeli Ilenia M.; Tisato, Nicola; Vasconcelos, Crisogono; Bernasconi, Stefano M.; Gonzales, Esteban R. G.; De Waele, Jo
Calculating flux to predict future cave radon concentrations, Rowberry, Matt; Marti, Xavi; Frontera, Carlos; Van De Wiel, Marco; Briestensky, Milos
Microbial mediation of complex subterranean mineral structures, Tirato, Nicola; Torriano, Stefano F.F;, Monteux, Sylvain; Sauro, Francesco; De Waele, Jo; Lavagna, Maria Luisa; D’Angeli, Ilenia Maria; Chailloux, Daniel; Renda, Michel; Eglinton, Timothy I.; Bontognali, Tomaso Renzo Rezio
Evidence of a plate-wide tectonic pressure pulse provided by extensometric monitoring in the Balkan Mountains (Bulgaria), Briestensky, Milos; Rowberry, Matt; Stemberk, Josef; Stefanov, Petar; Vozar, Jozef; Sebela, Stanka; Petro, Lubomir; Bella, Pavel; Gaal, Ludovit; Ormukov, Cholponbek;
See all featured articles from other geoscience journals

Search in KarstBase

Your search for aggregation (Keyword) returned 8 results for the whole karstbase:
Karst-like features in badlands of the Arizona Petrified Forest, 1963, Mears Brainerd,
Sinks, disappearing streams, hanging valleys, and natural bridges add a karst-like element to the miniature mountain topography represented in badlands. The Chinle Formation [Triassic] of the Petrified Forest in Arizona largely consists of compact, montmorillonitic and illitic claystones. Sinks in it result from disaggregation of swelling clay minerals rather than solution which affects limestone in true karsts. Ravines whose bottoms are pierced by sinks may develop into hanging valleys because their channels, robbed of surface flow downstream from these swallow holes, cannot keep pace with downcutting in the master drainage to which they are tributary. Growth of the sinks soon creates a disappearing stream that continues to deepen the upstream segment of a ravine. Thus the abandoned downstream segment beyond the sinks, no longer eroded by the stream, develops into a transverse barrier. Where the abandoned channel was initially short, the barrier may be eventually narrowed by weathering and slope erosion to form a natural bridge. Other bridges consist of jumbled material. that has collapsed from steep valley walls, undercut by small stream meanders

Observations on the Eastern Horse-Shoe Bat in North-Eastern New South Wales , 1966, Dwyer, P. D.

Between July, 1960, and December, 1963, observations were made on the natural history of Rhinolophus megaphyllus Gray in north-eastern New South Wales. Typically the species occurs as small colonies in a wide variety of cave and mine roosts. It appears to be absent from available roosting sites at higher altitudes in this area. Seasonal changes in the sizes of testes and epididymides suggest that mating occurs in May and June. The single young are born at maternity colonies through November, and nursing lasts about eight weeks. Field weights do not reflect seasonal variation other than that associated with pregnancy. However, seasonal differences in daytime level of activity are noted and these correlate with behavioural changes apparently related to temperature selection. Changes in colony size are described for several roosts and three movements made by marked individuals are recorded. Males appear to be more sedentary than females. Considerable aggregation of females and their young at maternity colonies (size, 15 to 1,5000 individuals) characterises the spring and summer population.


Deforestation in the Dominican Republic: a village-level view, 1997, Brothers Ts,
Deforestation is still rapid in some parts of the Caribbean, though it has attracted much less attention than deforestation in mainland Latin America. This paper examines the history and causes of the recent rapid deforestation of a lowland karst region of the Dominican Republic in the light of models derived from studies in Central America and the Amazon. Investigation was limited to the vicinity of a single village (Los Limones). Information was drawn from interviews, questionnaires and ground reconnaissance, in addition to archival information and aerial photographs. Deforestation at Los Limones involved many of the same elements seen in mainland deforestation, including construction of access roads, spontaneous agricultural colonization, and pasture conversion, but it followed no single mainland model. Logging, not normally emphasized as a cause of Latin American deforestation, played an important role in opening up the forest to agricultural settlement. Pasture conversion was not a matter of aggregation of large ranches by wealthy absentee landowners, as in the Amazon, but apparently a local response to the economic and ecological advantages of cattle raising. Government actions strongly influenced deforestation, but not via colonization schemes or economic subsidies for cattle ranching; the rhythm of deforestation at Los Limones was tied to the monopolistic practices of the dictatorship of Rafael Trujillo and the social disorganization following his assassination. The national government in fact bears the primary responsibility for deforestation of Los Haitises, a conclusion that contradicts the government's own suggestion that the destruction was largely carried out by poor farmers. Prospects for rehabilitation of the deforested area are gloomy because of the extent of ecological damage and the continued adversarial relationship between the government and the rural population

Evolution of size distributions of natural particles during aggregation: modelling versus field results, 1998, Atteia O,
In this paper a discretized model simulating aggregation of size distributions jointly with sedimentation and transport is presented. A review of the current theory provides some helpful hints about the relative importance of each aggregation process, i.e. Brownian motion, shear flow and differential sedimentation, which are tested by using collision efficiency factors. The novel aspect of the model arises from the use of a varying mean particle diameter in each size class. This allows both non-steady-state and steady-state calculations and free choice of size classes. A comparison with a classical approach shows the exactitude of the results and the improvment obtained for several cases. The simulations gave a family of curves characterized by three parts corresponding to peri-, and orthokinetic aggregation and to sedimentation. The role of collision effciency is crucial in the relative extent of each part of the size distribution. The comparison with a series of data from a karst spring showed that the model was able to fit most of the particle size distributions using significant values of each parameter. This allowed information about particle aggregation and transport within a non-accessible aquifer to be inferred.

Mn-Fe deposits in shallow cryptic marine environment: examples in northwestern Mediterranean submarine caves, 2001, Allouc J, Harmelin Jg,
Black coating of hard substrates by Mn and Fe oxides has long been reported from shallow, dark, submarine caves. However, these littoral metallic deposits have never been studied in detail, despite expected analogies with deep-sea polymetallic crusts. Submarine caves are characterized by darkness and low rates of exchanges with the open sea. Lack of primary production and confinement of inner water bodies result in marked oligotrophy and extremely reduced biomass, i.e. conditions close to those prevailing in deep-sea habitats. Field evidences suggested that the formation of Mn-Fe coatings was closely tied to these particular environmental conditions. The goal of this study was to examine the detailed features of Mn-Fe coatings from dark caves with different local conditions, and to try to identify the processes responsible for their deposition. Study sites and methods Three sublittoral, single-entrance, caves were sampled by scuba diving along the coasts of Provence (France, Mediterranean Sea) (fig. 1). The first site is a large karstic cave (Tremies Cave, 16 m depth at entrance floor, 60 m long; Marseille-Cassis area) with an ascending profile which results in a buffered thermal regime and markedly oligotrophic conditions due to warm water trapping in its upper part (fig. 1 and 2). Wall fragments were sampled at 30 m (medium confinement : zone B) and 60 in (strong confinement : zone C) from the cave entrance. The second site is a large tubular cavity open in conglomerate formations (3PP Cave, 15 m depth at entrance floor, 120 m long; La Ciotat) with a descending profile which results in relative permanence of winter temperatures within the inner parts, complex water circulation and presumed greater input of sedimented particles than in the preceding cave (fig.1 and 2). Wall samples were taken at 25 m, 70 in and 100 m from entrance. The third site is a small, horizontal, cave open in quartzite formations (Bagaud Cave, 7 in depth at entrance floor, about 10 m long; WNW of Port-Cros Island, bay of Hyeres). Sampling was performed on walls of a narrow corridor between an anterior room and a smaller inner room. A sporadic outflow of continental waters is located in the inner room. The samples were preserved in 50% ethylic alcohol or studied soon after their sampling. Before carbon coating and SEM examination, or microanalyses with SEM-associated spectrometers, they were treated in a 33% Chlorox solution and thereafter washed in demineralized water and dried. Micromorphology At low-medium magnification (<20,000), the aspect of coatings varies between caves and, especially, between inner-cave locations. All the described structures are made up of Mn and Fe oxides. In Tremies Cave, coatings of walls from zone B are composed of irregular erected constructions (height : 10s to 100s μm) formed by the aggregation of roughly ovoid primary concretions of about 10 μm (fig. 3). The surface of those primary concretions displays numerous lacunose to reticulate films (pores, about 0.5 μm in diameter, are often subrounded). Remnants of these films and organomorphic corpuscles occur also within the primary concretions (fig. 4). On younger substrates (broken wall exposed since 1970), primary concretions are poorly developed and no prominent construction is visible (fig. 5). In more confined conditions (zone C), the erected constructions of ancient coatings are smaller and less numerous than in zone B but are well individualized (fig. 6). In this zone: C, besides some remnants of lacunose to reticulate films (fig. 7), there is an appearance of filaments and ovoid corpuscles (height/width : 10-30/5-15 μm), which seem to be linked to filaments by a short stalk (fig. 8). In 3 PP Cave, at 25-70 m from entrance, wall coatings present porous heaps of primary concretions (fig. 9). The surface and the inside of the latter comprise remnants of lacunose to reticulate films that evoke those observed in Tremies Cave (fig. 10 and 11). On younger substrates (hard parts of sessile invertebrates), coatings are restricted to micrometric organomorphic corpuscles with some remnants of lacunose or fibrous films (fig. 12). At 100 in from the entrance, coatings are shaped by numerous erected constructions, more or less coalescing (fig. 13). Besides remnants of lacunose films, the primary concretions contain interlacing filaments (diameter : 0.2-0.3 μm) forming cords or veils (fig. 14). In Bagaud Cave, the primary concretions are aggregated in irregular heaps (fig. 15). Lacunose films are particularly frequent and tend to form three-dimensional mamillated structures that were not observed in the other caves (fig. 16). In particular, there is an appearance of tubular structures (fig. 17) and of numerous hemispheroidal structures (diameter : 4-5 μm) with an upper orifice (fig. 18 and 19). At higher magnification (20,000), whatever the cave and inner-cave location, the aspect of oxide deposits is rather smooth or, especially, microgranular (fig. 20). Mineral composition The composition of coatings is different between caves and according to their inner-cave location. In both large caves (Tremies and 3 PP), the Mn/Fe ratio increases with the distance from the cave entrance, i.e. when exchanges with the open sea diminish (fig. 21a). This trend is particularly clear in Tremies Cave, where the confinement gradient is strongly marked. Besides, the Mn/Fe ratio also seems to increase when films are present in the analysed volume (some cubic micrometers) (fig. 21b). In Bagaud Cave, the Mn/Fe ratio reaches high values despite the small size of this cave and its low confinement level. Discussion and conclusions SEM observations suggest that in each studied cave, the Mn-Fe coatings are biosedimentary deposits. Genesis of these deposits is assumed to result mainly from the replacement of biofilms (composed of cells and slime, i.e, of extracellular polymeric substance produced by microorganisms) generated by microbial populations colonizing the cave walls. Considering the darkness of the cave-locations, microbes consist mainly in bacteria, but fungi are probably responsible for the filaments and ovoids corpuscules (evoking sporocysts) occurring in innermost parts. Observations at different scales of the morphological features of oxide deposits reveal a structured organisation which varies along the strong environmental gradients (particularly the confinement level) that occur from the entrance to the innermost parts : erected constructions made up of primary concretions become more and more defined and acquire a pseudo-columnar shape. The aspect of biofilms appears to be controlled by the same environmental parameters. In open or relatively open environments, they frequently show a three-dimensional development (with frequent skullcape-like shapes), while in more confined conditions they exhibit a planar layout. These changes reflect either the adaptation of the slime-producing bacteria to the local trophic resources (correlated to the rate of exchange with the open sea) and water movements, or spatial replacement of taxa. It is assumed that slime (mainly composed of water and exopolysaccharides) induces a local increase of the concentration in dissolved Mn and acts as an ion exchange resin that allows the retention of Mn on the functional groups of EPS. These conditions promote the nucleation of Mn oxide crystallites in the slime. Then. the anionic character of Mn oxides in seawater, and their capacity to catalyse the oxydation of Mn2 to Mn4, allow the process to go on without any other biological intervention; thus, the process of crystal growth becomes possible. In caves where Mn is only supplied by seawater (Tremies and 3 PP), the average value of the Mn/Fe ratio of coatings is negatively correlated to the local availability of nutrients. This trend is probably linked to changes in the selectivity of slimes towards the processes of retention of cations, because this ratio is clearly influenced by the occurrence of biofilms. However, independently from trophic resources, the Mn/Fe ratio can be notably increased when additional Mn is provided by the seeping or flowing of continental waters (Bagaud Cave)

Aggregate Protection Against Dehydration in Adult Females of the Cave Cricket, 2002, Yoder, J. A. , Hobbs, Iii, H. H. , Hazelton, M. C.
The role of aggregation in water conservation in adult female cave crickets, Hadenoecus cumberlandicus, in Laurel Cave (Carter Co., KY) was investigated. Grouped crickets retained water more effectively (water loss rates were lower) as densities increased from 1, 5, 10 and 20 crickets per cluster. Dry air currents (flow rate 43 mL/min) that passed over an aggregation of 20 eliminated the group effect with regard to water loss, suggesting that the mechanism operates by raising the relative humidity inside the cluster. Rapid water loss rate characterizes the water balance profile and is reflected by high activation energies for water loss and low quantities of cuticular lipid. There was no evidence for water vapor uptake. Natural gains and losses are high in H. cumberlandicus, and this agrees with their preference for the deep cave environment. Conversely, water turnover is lower for another trogloxenic cricket, Ceuthophilus stygius, that is less cave-adapted.

Disaggregation modelling of spring discharges, 2004, Kirilova Bojilova Elena
Disaggregation models are basically divided into three main groups: temporal, spatial and temporal-spatial. The focus of this paper is the application of temporal disaggregation models to disaggregate the seasonal flow in some large time intervals to sub-seasonal flows in some shorter time intervals. Two basic models are applied: the original model of Mejia and Rousselle and the corrected extended Lin model one-stage disaggregation. The flow totals from some karstic springs are used. Data for five springs in different areas of Bulgaria for the aims of the study are executed. The synthetic data generation for the chosen spring stations for a new realisation of thirty years is obtained. The multi-variate lag-one auto regressive model (AR(1) model) is applied for generation of the annual flow sequences. The Lin model single- site is performed for thirty years generation period. The Lin model is an improvement compared to the original extended model. The new Lin approach succeeds in the preservation of the additivity as well as the moments. Applying the Lin model one-stage disaggregation results in consistent model parameter estimates. As a second step in the research multi-site disaggregation schemes are also applied.

Geomorphology and genesis of the remarkable Araras Ridge tufa deposit, Western Brazil, 2011, Corrê, A Daniel, Auler Augusto S. , Wang Xianfeng, Edwards R. Lawrence, Cheng Hai

The Araras Ridge tufa extends for over 30 km along a c. 100 m high fault scarp, probably representing one of the most extensive tufa deposits in South America. The deposit comprises massive crystalline calcite occurring both as in situ tufa deposited along the vertical face of the scarp or as extensive debris deposits resulting from erosional disaggregation of the scarp. Although minor active tufa precipitation can be observed in streams, the deposit is not active at present, except for volumetrically limited reprecipitation of calcite as subaerial stalactites or surface flowstone. 230Th dating confirms that the bulk of the deposit is considerably old, basal ages being beyond the dating limit of the method (> 600 ka B.P.) and most ages being older than 250 ka B.P. Field and remote sensing observations demonstrate that the upper limit of the deposit parallels the fault scarp, being associated with the contact between the upper dolomitic and the lower limestone members of the Araras Formation. Carbonate beds are arranged in a regional scale synclinal structure that allows water infiltration and storage at the top of the more impure limestone, favouring discharge at the ascending limb of the syncline, close to the scarp. Genesis of the deposit thus probably involved a series of palaeo perched springs aligned along the top of the scarp. Current climatic and geomorphic conditions are not conductive to major tufa development, suggesting a distinct palaeoenvironment during former depositional phases.


Results 1 to 8 of 8
You probably didn't submit anything to search for