MWH Global

Enviroscan Ukrainian Institute of Speleology and Karstology


Deprecated: Function get_magic_quotes_gpc() is deprecated in /home/isthin5/public_html/addon-domains/speleogenesis.info/template/toolbar_left.php on line 5
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. ...

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 blue hole is 1. deep resurgence pool, notably in jamaica and florida, that may have a blue color due to the presence of algae. also a deep submarine cave of the bahamas. the latter type are large flooded shafts cut into the limestones of the shallow reefs and lagoon floors. many are 100 m in diameter and some are 100 m deep. opening from the shafts are flooded cave passages at various depths, some of which have been explored subhorizontally for more than 1 km. their origins are complex. extensive stalagmite deposits show that large old caves were drained when sea-levels were low during the pleistocene (when water was held in the ice sheets). they are now being modified by marine dissolution, notably at the interface between fresh and salt waters (sea littoral zone) and by powerful tidal flows between connected holes [9]. 2. (jamaican.) a major emergence where water (artesian spring) rises from below without great turbulence. 3. (bahamas.) a drowned solution sinkhole [10]. 4. caribbean expression for a major quiet up-welling karst spring inland or along the coast. the blue color is due to the scattering of sunlight by water molecules, although in some cases it may be attributed to the presence of calcareous algae [20]. synonyms: (french.) source bleue (jura), bleu-fon (south of france); (german.) blaue grotto; (greek.) galapo speleo. see also boiling spring.?

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


Deprecated: Function get_magic_quotes_gpc() is deprecated in /home/isthin5/public_html/addon-domains/speleogenesis.info/template/toolbar_right.php on line 7
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 slopes (Keyword) returned 106 results for the whole karstbase:
Showing 31 to 45 of 106
Karst in Enclosing Rocks of Kimberlite Diatremes on the Siberian Platform , 1998,
Deprecated: Function get_magic_quotes_gpc() is deprecated in /home/isthin5/public_html/addon-domains/speleogenesis.info/include/functions1.php on line 943
Filippov, Andrej G.

Karst is widely developed in enclosing carbonate rocks of kimberlite diatremes in Yakutia. The Lower Silurian, and Lower and Middle Ordovician marine carbonate and carbonate-terrigenous rocks were exposed to karstification. The age of the forms is Middle and Upper Carboniferous, Cretaceous-Paleogene, Neogene-Quaternary and Quaternary. Karst forms are found on different elements of macro-relief, such as the top part of high plateaux armoured by traps, high plateau slopes, low carbonate plateaux. With respect to elements of meso-relief, karst has developed in watersheds, valley slopes, and under the bottoms of valleys.


Rakovska kukava - collapse or tumour doline? , 1998,
Deprecated: Function get_magic_quotes_gpc() is deprecated in /home/isthin5/public_html/addon-domains/speleogenesis.info/include/functions1.php on line 943
Š, Uš, Terš, Ič, France

This paper deals with one of the largest presumed collapse dolines lying about 2km northeast of the Planinsko polje in Slovenia. Within it, true rock faces are only locally present. The rest of the rocky slopes are to some degree inclined, and many of them are only slightly too steep to support a soil mantle ("normal slopes"). Screes are found in the central part of the doline. In the lowest part of the depression a 45m-long and 20m-wide secondary depression lowered into the screes is evident that leads to the conclusion that, after scree slope formation under one set of slope equilibrium conditions, a subsequent process has removed material from the centre. This was confirmed by mathematical model. The process may continue until so much rock is removed that the stream appears on the surface.


Land use in the karstic lands in the Mediterranean region, 1999,
Deprecated: Function get_magic_quotes_gpc() is deprecated in /home/isthin5/public_html/addon-domains/speleogenesis.info/include/functions1.php on line 943
Atalay Ibrahim
Karstic lands have special importance in terms of soil formation and land-use. Soil appears only on the flat and slightly undulating karstic lands, while soils are found along the cracks and bedding surfaces between the layers on the hilly karst areas although these lands are rocky in appearance. Karstic lands in the hilly area are not conducive to cultivation. But rocky areas create a favourable habitat for the growth of forests except in an arid climate. Because the tree roots easily follow and develop along the cracks in the limestone. As a general rule soil erosion does not occur on sub-horizontal karst surfaces due to the fact that atmospheric waters easily infiltrate along the cracks. Natural generation of vegetation like the maquis-type occurs via the root suckers, but coniferous trees such as cedar, fir, pine through seed dispersal. The clearance of natural vegetation on the karstic lands leads to the formation of bare lands. That is why the slopes of the limestone hillsides have been converted into bare and/or rocky terrains in places where natural vegetation has been completely destroyed.

Agriculture, landscape and human impact in some karst areas of Italy, 1999,
Deprecated: Function get_magic_quotes_gpc() is deprecated in /home/isthin5/public_html/addon-domains/speleogenesis.info/include/functions1.php on line 943
Burri Ezio, Castiglioni Benedetta, Sauro Ugo
Italy is made up for about 1/5 of its surface by soluble rocks, which represent the arena of karst environments. The karst morpho-units, some hundreds, are mainly distributed inside the alpine structure of the Mediterranean mountains. A very large number of rock formations are present, different in facies, lithology, age, etc. Among these, carbonate rocks prevail, followed by gypsum and salt. Most of the carbonate rocks are limestones sedimented in a platform environment and they show a wide range of porosity, frequency of fractures and bedding planes. The climatic processes, the expression of some different sub-types of Mediterranean climate (from the typical Mediterranean to sub-atlantic and sub-continental varieties), are the main control of the recent morphodynamics inside the karst morpho-units. In some areas the variability of precipitation is very high. The soil-water deficit during summer, together with the steep slopes, makes these environments highly vulnerable to human impact, especially in relation to soil use for grazing and agriculture. The soils, with enriched mineral contents from the fall of loess-like sediments or of volcanic ashes, were surely very appealing to the first farmers.

Facies differentiation and sequence stratigraphy in ancient evaporite basins - An example from the basal Zechstein (Upper Permian of Germany), 1999,
Deprecated: Function get_magic_quotes_gpc() is deprecated in /home/isthin5/public_html/addon-domains/speleogenesis.info/include/functions1.php on line 943
Steinhoff I. , Strohmenger C. ,
Due to excellent preservation, the Werra Anhydrite (Al), the upper member of the Upper Permian Zechstein cycle I (Ist cycle, Z1), is readily studied in terms of the distribution of sulfate facies and sequence stratigraphy that can be interpreted from these facies. In this study cores taken from seven wells in the Southern Zechstein Basin were examined for their sedimentary structures and various petrographic features. Facies interpretation and depositional sequences are based on detailed examination of core material. Four main facies environments have been identified: (I) supratidal (II) intertidal (III) shallow subtidal, and (IV) deeper (hypersaline) subtidal. These are further subdivided into 10 subfacies types: (1) karst and (2) sabkha within the supratidal environment (I), (3) algal tidal-flat, (4) tidal flat and (5) beach deposit within the intertidal environment (II), (6) salina, and (7) sulfate arenites within the shallow subtidal enviromnent (III). The (8) slope subfacies type commonly associated with (9) turbidites and the (10) basin subfacies type subdivide the deeper subtidal environment (IV). Vertical stacking patterns of these facies and subfacies types reveal the sequence stratigraphic development of the sulfate cycles in response to sea-level and salinity fluctuations. The lower Werra Anhydrite (belonging to Zechstein Sequence ZS2) is characterized by a transgressive systems tract (IST) overlying the transgressive surface of Zechstein Sequence ZS2 within the Al-underlying upper Zechstein Limestone (Cal). The TST of the AT is several tens of meters thick in platform areas, where it is built up by sulfate arenites and swallow-tail anhydrite-after-gypsum, and thins out to a few meters of thickness toward the condensed basinal section, where laminites ('Linien-Anhydrit') are predominant. Most of the Al succession consists of three relatively thick parasequences belonging to the highstand systems tract (HST) that shows typical prograding sets. Enhanced platform Buildup, including sulfate arenites, salina deposits, intertidal sediments, and sabkha precipitation as well as turbidite shedding off the platforms produced marginal ''sulfate walls' up to 400 m thick as platform to slope portions of the Werra Anhydrite. Seaward, the Al thins to a few tens of meters of laminated sulfate basin muds. Increasingly pronounced Al topography during highstand narrowed the slope subfacies belt parallel to the platform margin This contrasts with the broad but considerably thinner slope deposits of transgressive times with much shallower slopes. The ensuing sea-level lowstand is reflected by a sequence boundary on top of the karstified Al-platform and a lowstand wedge (Zechstein Sequence ZS3) overlying portions of the slope and basinal subfacies of the Al highstand systems tract Beyond the lateral limits of the lowstand wedge, the sequence boundary merges with the transgressive surface of ZS3, shown by the lithologic change from the Al anhydrites to the overlying carbonates of the Stassfurt Carbonates ('Haupt Dolomit' Main Dolomite, Ca2). The Basal Anhydrite (A2), which overlies and seals the carbonate reservoir of the Ca2, can also be subdivided into systems tracts by means of facies analysis. It is, however, much less complex than the Al and is comprised almost exclusively of a transgressive systems tract of Zechstein Sequence ZS4

Karst landforms on the eastern slopes of Davras Dagi (western Taurus): karren, sinkholes and uvalas, 1999,
Deprecated: Function get_magic_quotes_gpc() is deprecated in /home/isthin5/public_html/addon-domains/speleogenesis.info/include/functions1.php on line 943
Dayan E, Bilgin A, Hancer M,
A characteristic of the study area is the low frequency of gully and rill karren. By length, width and depth they are not comparable with the same type of karren in the alpine karst, as they have attained only insignificant dimensions. This difference in size cannot primarily be attributed to differences of annual precipitation, but rather to the fact that they are only 2-3000 years old. Their formation started with anthropogenic forest destruction and concomitant soil stripping. As gully and rill karren depend on bare rock surfaces for their formation, they cannot have formed before that time. Joint-oriented and cavernous karren, in conrast, are widely spread in the study area. As the formation of these two types of karren is related to the existence of joints, their frequency is explained by severe fracturing of the limestone during recent tectonic movements. Although cavernous karren may also form on bare rock surfaces, Lest conditions for their development exist underneath a soil cover. As this no longer exists, the formation of cavernous karren has become much reduced in the historical era. Sinkholes are frequent in the planation surfaces of Mid- to Upper Miocene age and are of Pliocene and Pleistocene age. The uvalas are also not very old, as many of them contain terra rossa

Quelle est la dimension du massif karstique de la Sainte-Baume ? Elments pour une thorie spatiale et fractale du karst, 2000,
Deprecated: Function get_magic_quotes_gpc() is deprecated in /home/isthin5/public_html/addon-domains/speleogenesis.info/include/functions1.php on line 943
Martin, Philippe
The dimension of the surface of Sainte Baume and its neighbourhood is close to 2,2. This value has been obtained the study of 5 contour lines (from 400 to 800 m) and 5 topographic profiles (3 N - S and 2 E - W). 3 methods were used for contour lines: box counting (DB); the information dimension (Di) and surface - perimeter relation (D(P)). Three methods have been used for topo_graphic profiles: the power spectrum (DSPEC); statistics R/S (DR/S) and vario_gramme (DVAR). Average results are: (DB) = 1.20; Di = 1.23; (D(P)) = 1.32; DSPEC = 1.17; DR/S = 1.24; DVAR = 1.23. Thus, the surface of Sainte Baume and its neighbourhood is fractal. It means, theoretically, that Sainte Baume can be characterised by an infi_nite surface in a bounded volume. This first approach focuses on karst surface approach, cave systems approach will be presented in a following paper (in this review). This result raises numerous geomorpho_logic questions. How to calculate a specific erosion? How to think forms in a theoretical frame, which could develo_ped out of the Euclidean geometry conventions? How to think an essential_ly irregular morphology? Elements of answer are brought on a theoretical plan. They constitute the first elements of a karst geometrical theory. Calculation of the specific erosion points out the problem of the size of the surface used. Due to fractal theories, this size is relative to the observation scale used. To be significant, specific erosion calcula_tion needs the use of an efficient scale, in regard of the erosion processes studied. Furthermore, specific erosion expresses only a balance of mass, not a morphoge_nesis. It corresponds to a chronological approach of the karst. Two dynamics can be distinguished in surface morphogenesis. In one hand, increase of the mean slopes is named spatial differentiation, in another hand, decrease of this value is classically called: aplanation or levelling. These 2 dynamics imply the wearing away of spatially various materials. It takes place essentially around thalwegs during the differentiation stage, around the crest during levelling. Thus morphology, space are important factors of the dynamics in the work. Space is not only a support, but an actor in morphogenesis.

Field survey and analysis of hillslopes on tower karst in Guilin, southern China, 2000,
Deprecated: Function get_magic_quotes_gpc() is deprecated in /home/isthin5/public_html/addon-domains/speleogenesis.info/include/functions1.php on line 943
Tang T. , Day M. J. ,
Limestone dissolution in tropical and subtropical humid southern China created residual hills with steep slopes, a landform that is referred to as tower karst. Two types of tower karst landform feature, fenglin or peak forest (isolated towers) and fengcong or peak cluster (linked-base towers), were identified in Guilin. Previous studies proposed two hypotheses regarding their origin and evolution. One is the sequential evolution model from peak cluster to peak forest. The other is a parallel development model, which postulates that both peak cluster and peak forest have developed simultaneously. Through detailed field survey and analysis of slope forms on tower karst in Guilin, it was found that the mean slope angle of the towers is very high (62.4 degrees) and ranges from 60 degrees to 75 degrees. There is no significant difference in mean slope angle and slope angle distribution between towers in the peak cluster basin and peak forest floodplain areas. Mean slope angle increases with intensified fluvial dissection. Three levels of caves in the towers of the peak forest in Guilin were identified in previous research. The isolated towers of the peak forest as well as scattered residuals of peak cluster are generally distributed in the centre of the Guilin syncline. Favourable circumstances of allogenic water concentration indicate that development of the peak forest resulted from the combined effects of subcutaneous and subterranean dissolution as well as subsequent collapse and recession by fluvial erosion after uplifting. By contrast, peak clusters generally occur on the limbs of the syncline or at the periphery of the Guilin basin with relatively higher elevations. The thick vadose zone and predominantly vertical flow suggests that peak clusters are mainly formed by the combination of intensive uplifting and the enhancement of original dolines. The evidence of slope survey and slope analysis suggests that both isolated towers and linked-base towers developed simultaneously but by different mechanisms of formation and different combinations of development processes. Copyright (C) 2000 John Wiley & Sons, Ltd

Determination of escarpment age using morphologic analysis: An example from the Galilee, northern Israel, 2000,
Deprecated: Function get_magic_quotes_gpc() is deprecated in /home/isthin5/public_html/addon-domains/speleogenesis.info/include/functions1.php on line 943
Matmon A. , Zilberman E. , Enzel Y. ,
We used topographic and structural data and very limited age control to perform quantitative morphometric analyses and to determine relative ages of escarpments bounded by late Cenozoic normal faults in the Galilee, Israel. The Galilee is an extensional zone composed of a series of uplifted and tilted blocks forming large escarpments built mainly of carbonate rocks. Two parameters used to discriminate tectonic stages are the ratio between the height of the escarpment and the total stratigraphic displacement (L) and the degree of concavity of escarpment slopes relative to a reference slope. The only dated reference slope is Mount Tur'an, [~]300 m high and formed by the Tur'an fault system, which has a total stratigraphic displacement of 625 m. A basalt flow that delimits the age of the Tur'an escarpment is dated to 4.23 {} 0.23 Ma and displaced 300 m, which is identical to the present-day topographic expression of this escarpment. The L value for this escarpment is [~]0.5. The Tur'an fault system was active prior to 4.23 Ma at slow uplift rates that enabled erosion to maintain the gentle slope over which the basalt flowed. Increased offset rates following the basalt extrusion led to the formation of the escarpment. The preservation of the basalt at the top of the escarpment indicates that erosional lowering of the upper surface of the Tur'an block has been minor since its formation. The L values indicate two stages of uplift; an early stage during which offset rates were probably low enough that they did not form topography, and a later stage that formed topography, which is preserved. The timing of the change in displacement rates from a slow continuous stage to a fast, topography-forming stage was determined by comparing the shape of the dated slope of Tur'an to that of other slopes. We conclude the following: (1) generally, the topographic profiles of different parts of each individual escarpment have similar shapes indicating similar ages; (2) escarpments having slopes that are more concave or convex than the reference Tur'an escarpment are older or younger than 4 Ma, respectively; and (3) the Galilee escarpments did not form simultaneously. A few escarpments were already major morphologic features by the early to middle Pliocene, whereas the rest formed during the late Pliocene. Morphometric analysis is a useful method for studying the geologic history of a landscape controlled by normal fault uplift and characterized by the absence of sediment deposition and where carbonate dissolution is the main erosional process. This and similar approaches can be used to discriminate tectonic stages and understand the relationship between tectonic activity and surface processes in other extensional regions

Geographic information systems analysis of geologic controls on the distribution on dolines in the Ozarks of south-central Missouri, USA, 2000,
Deprecated: Function get_magic_quotes_gpc() is deprecated in /home/isthin5/public_html/addon-domains/speleogenesis.info/include/functions1.php on line 943
Orndorff Randall C. , Weary David J. , Lagueux Kerry M.

The geologic controls on the distribution and development of dolines in the Salem Plateau of the Ozark Plateaus Province, south-central Missouri, USA, was statistically analyzed by using a geographic information system. The controls include lithostratigraphy, geologic structure, slope, and depth to water table. Area and point data for 2,613 dolines in two 30'¥60' quadrangles were compiled on a 30-meter grid. The percent area of dolines was calculated for five lithostratigraphic units, and it was determined that the Jefferson City Dolomite and Roubidoux Formation have the highest density of dolines. A focal sum neighborhood analysis was performed to determine if the distribution of dolines had any clustering or linearity that may suggest structural control. A northwest alignment of doline clusters occurs along a projection of the Bolivar-Mansfield fault zone in south-central Missouri. Most dolines in the study area occur on the plateau areas and on gentle slopes rather than in the highly dissected areas. Intense fracturing near regional fault zones may enhance doline development on the plateau areas. An understanding of the karst system is important for better land-use management practices in the Ozarks, including conservation of natural resources, ground-water management, and environmental protection, especially because the study area includes potential economic lead and zinc mineralization.


Velika Jeršanova doline - a former collapse doline, 2000,
Deprecated: Function get_magic_quotes_gpc() is deprecated in /home/isthin5/public_html/addon-domains/speleogenesis.info/include/functions1.php on line 943
Š, Ebela Stanka, Č, Ar Jož, E

The Velika Jeršanova doline (a.s.l.=535 m) is situated on the surface above the Postojnska Jama cave system. Its deepening undoubtedly interrupted the continuation of Pisani rov (a.s.l.=535,5 m) towards N. Through the Velika Jeršanova doline the Postojna anticline crest runs in the direction of NW-SE. The same direction has also the Jeršan fault. Strike and dip of thin bedded Turonian and Cenomanian limestones are disordered on the anticline's crest. The limestones dip 5-25°. The Velika Jeršanova doline today does not have the typical shape of a collapse doline. The main cause for the untypical collapse shape of Velika Jeršanova doline is its formation in the Postojna anticline crest, its shaping in thin bedded clay - rich limestones and intensive erosional lowering of the area. Regarding the actual shape of the slopes and outer edges, the Velika Jeršanova doline is a relic of a former well shaped collapse doline.


Are "collapse dolines" formed only by collapse?, 2000,
Deprecated: Function get_magic_quotes_gpc() is deprecated in /home/isthin5/public_html/addon-domains/speleogenesis.info/include/functions1.php on line 943
Š, Uš, Terš, Ič, France

The paper concerns collapse dolines, which appear to be one of the best-defined surface karst phenomena. Despite this appearance, one may find quite different views in the literature, and some the aspects of their morphogenesis have been overlooked completely. Among these aspects the most obvious is the question of the ongoing development of the closed depression. After the perpendicular walls have disappeared, the slopes are reshaped only by pocket weathering, and denudation penetrates deep below the former level of the pre-existing cave floor. Dolines at this stage of development have been termed phantom collapse dolines. Five of the most common collapse doline types found in Slovenia are considered in terms of general systems theory, leading to a conclusion that cave roof collapse remains the crucial event in a collapse doline's development. However, the collapse event itself may be relatively subdued in terms of the volume of free fallen mass involved.


Engineering-geological problems in the Moravian karst, Czech Republic, 2001,
Deprecated: Function get_magic_quotes_gpc() is deprecated in /home/isthin5/public_html/addon-domains/speleogenesis.info/include/functions1.php on line 943
Samalikova M. ,
The Moravian karst belongs to one of the famous karst regions in Central Europe. It is situated in Moravia in the eastern part of the Czech Republic. According to the geology it is of Devonian age and the main rocks are of different types of limestones. The process of karstification is still active. They are many caves with rich stalagmites and stalactites and Macocha abyss, the depth of which is 138.5 m. The underground Punkva River flows through the main part of the karst, forming beautiful underground lakes. Typical karst phenomena, such as sinkholes and deep canyons, may be observed on the surface of the terrain. Because of the karstification, water erosion and frost weathering, many steep unstable slopes and walls originated. To solve the stability from a geotechnical point of view is not easy. This requests a special engineering-geological knowledge and experience

Geological hazards in loess terrain, with particular reference to the loess regions of China, 2001,
Deprecated: Function get_magic_quotes_gpc() is deprecated in /home/isthin5/public_html/addon-domains/speleogenesis.info/include/functions1.php on line 943
Derbyshire E,
The considerable morphodynamic energy provided by the continuing tectonic evolution of Asia is expressed in high erosional potentials and very high rates of sediment production that make this continent unequalled as a terrestrial source of primary silt. Many of these environments are hazardous, threatening human occupation., health and livelihood, especially in regions of dense population such as the loess lands of north China. Dry loess can sustain nearly vertical slopes, being perennially under-saturated. However, when locally saturated, it disaggregates instantaneously. Such hydrocompaction is a key process in many slope failures, made worse by an underlying mountainous terrain of low-porosity rocks. Gully erosion of loess may yield very high sediment concentrations ( > 60% by weight). Characteristic vertical jointing in loess influences the hydrology. Enlarged joints develop into natural sub-surface piping systems, which on collapse, produce a 'loess karst' terrain. Collapsible loess up to 20 m thick is common on the western Loess Plateau. Foundation collapse and cracked walls are common, many rapid events following periods of unusually heavy monsoonal rain. Slope failure is a major engineering problem in thick loess terrain, flow-slide and spread types being common. The results are often devastating in both urban and rural areas. An associated hazard is the damming of streams by landslides. The human population increases the landslide risk in China, notably through imprudent land-use practices including careless water management. A number of environmentally related endemic diseases arise from the geochemistry of loess and its groundwaters. including fluorosis, cretinism, Kaschin-Beck Disease, Keshan Disease and goitre. The Chinese desert margins also have a major atmospheric dust problem. The effect of such dust upon human health in these extensive regions, including many large cities, has yet to be evaluated, but pneumoconiosis is thought to affect several million people in north and west China. (C) 2001 Elsevier Science B.V. All rights reserved

Origine des grands vides souterrains du reseau de Muruk et role des seismes (montagnes Nakanai), 2001,
Deprecated: Function get_magic_quotes_gpc() is deprecated in /home/isthin5/public_html/addon-domains/speleogenesis.info/include/functions1.php on line 943
Audra Ph.
Papua New Guinea is one of the world's most active seismic areasOn the surface, huge landslides are found on mountainsides and steep canyons slopesUnderground large passages and megadolines result mainly from the erosion of soft limestones by underground streams, but seismic movements accelerate their evolutionMorphological characteristics were derived from statistical data and field observations

Results 31 to 45 of 106
You probably didn't submit anything to search for