Km Of Passages Research Articles

Going with the flow: Sedimentary processes along karst conduits within Chalk aquifers, northern France

Sediment-filled caves, conduits and voids are common in many karst regions. These voids and the sediment they contain are important palaeoclimatic and palaeoenvironmental archives, but often have an adverse impact on engineering projects, mineral extraction and hydrogeology. Most studies into fluvial sedimentation in karst aquifers have focussed on more traditional karst areas. However, the nature and extent of fluvial sedimentation within caves and conduits in the important Upper Cretaceous Chalk Group aquifer (NW and Central Europe), and their impacts are less well known. This is principally due to a lack of accessible Chalk caves with exposed 3D sediment archives for study. Fortunately, the discovery of the World's longest Chalk cave system by underground quarrying at Caumont in the Seine valley near Rouen, northern France, has exposed numerous sediment sections along 2.4 km of passage. Detailed analysis of the stratigraphy, mineralogy, sedimentology, provenance and the chronology of the exposed sediments including the novel use of Gamma-ray spectrometry, reveals complex stratigraphy and lateral facies distribution along a karst conduit. The depositional model comprises five allostratigraphical units since the mid-Chibanian, separated by periods of erosion. The units are derived from hyper-concentrated and sediment-laden flows, and include thalweg, channel, slackwater, backswamp speleothem facies and debris flow deposits that are interbedded. Speleothems precipitated during MIS 7, 6, 5e and 1. During MIS 7–6, detrital sediments filled almost all Chalk conduits, similar to other caves in the European Atlantic Margin, coevally with the Penultima (Saalian) Glacial Cycle and a maximum of the Earth eccentricity. Detrital sediments are derived from the erosion of local Chalk bedrocks as well as metamorphic and igneous rocks of remote areas, such as Morvan massif and Massif Central. The depositional model is consistent with the conception of the Chalk as a karst aquifer. Significant sediment aggradation caused upwards dissolution (paragenesis), conduit occlusion and subsequent genesis of new conduits by flow diversion, potentially altering the functioning of the chalk aquifer and the interpretation of Chalk hydrogeology (e.g., dye-tracing tests).

What's the relative humidity in tropical caves?

Relative humidity (RH) was measured at hourly intervals for approximately one year in two caves at seven stations near Playa del Carmen in Quintana Roo, Mexico. Sistema Muévelo Rico is a 1.1 km long cave with 12 entrances and almost no dark zone. Río Secreto (Tuch) is a large river cave with more than 40 km of passages, and an extensive dark zone. Given the need for cave specialists to adapt to saturated humidity, presumably by cuticular thinning, the major stress of RH would be its deviation from saturation. RH in Río Secreto (Tuch) was invariant at three sites and displayed short deviations from 100% RH at the other four sites. These deviations were concentrated at the end of the nortes and beginning of the rainy season. Three of the sites in Sistema Muévelo Rico showed a similar pattern although the timing of the deviations from 100% RH was somewhat displaced. Four sites in Sistema Muévelo Rico were more variable, and were analyzed using a measure of amount of time of deviation from 100% RH for each 24 hour period. Strong seasonality was evident but, remarkably, periods of constant high humidity were not the same at all sites. In most Sistema Muévelo Rico sites, there was a detectable 24 hour cycle in RH, although it was quite weak in about half of them. For Río Secreto (Tuch) only one site showed any sign of a 24 hour cycle. The troglomorphic fauna was more or less uniformly spread throughout the caves and did not concentrate in any one area or set of RH conditions. Compared to temperature, RH is much more constant, perhaps even more constant than the amount of light. However, changes in RH as a result of global warming may have a major negative effect on the subterranean fauna.

Linking mineral deposits to speleogenetic processes in Cova des Pas de Vallgornera (Mallorca, Spain)

Cova des Pas de Vallgornera (CPV) is the premier cave of the Balearic Archipelago. Over 74 km of passages develop within two carbonate lithofacies (reef front and back reef), which ultimately control the patterns of the cave and to some degree its mineral infilling. The diversity of speleothem-forming minerals is four times greater around or within hypogene-related features (vents, rims, cupolas), compared to any other vadose passages in the cave. The mineralogy of speleothems (crusts, nodules, crystals, earthy masses) associated with hypogene features in the seaward upper maze of Sector F is characterized by the presence of aragonite, ankerite, huntite, clay minerals, and quartz. In the Tragus and Nord sectors, however, the dominant mineral is dolomite, along with aragonite, celestine, huntite, clay minerals, and quartz. Calcite is by far the most ubiquitous mineral throughout the cave. Detailed macroscopic and scanning electron microanalysis and imaging have permitted the investigation of textural relationships between the minerals associated with vents, rims, and vent’s roof and walls. These studies along with morphological and stable isotope analyses confirm that not all minerals are connected with a hypogene stage in the cave evolution, and furthermore, none of them appears to be sulfuric acid by-products. Instead, the mineral assemblages documented in speleothems from CPV clearly support at least three speleogenetic pathways, namely seacoast mixing, ascending of warm groundwaters, and meteoric recharge (vadose). Thus, cave minerals in Cova des Pas de Vallgornera hold the keys to reconstruction and understanding of processes and conditions under which they precipitated, allowing to establish their relationship with various speleogenetic pathways.

Mechanisms of englacial conduit formation and their implications for subglacial recharge

Ideas about the character and evolution of englacial drainage systems have been deeply influenced by the theoretical model developed by Shreve [1972. Movement of water in glaciers. Journal of Glaciology 11(62), 205–214]. The Shreve model is based on three main assumptions: (1) englacial drainage is in steady state; (2) englacial water will flow along the steepest hydraulic gradient within the glacier; and (3) pressure head equals the pressure of the surrounding ice minus a small component due to melting of the walls. The Shreve model has been widely adopted as a fundamental component of englacial drainage theory. There is no evidence, however, that the model provides a realistic picture of actual glacial drainage systems.To evaluate Shreve's theory, we used speleological techniques to directly survey englacial conduits. We mapped a total of 8.25km of passage in 27 distinct englacial conduits in temperate, polythermal, cold-based and debris-covered glaciers between 2005 and 2008. New information reported here is supplemented by published data on 40 other englacial conduits located worldwide and surveyed to ice depths of 176m using speleological techniques. In all cases, englacial drainage systems consisted of a single unbranching conduit. Englacial conduit morphologies were found to be intimately linked to the orientation of a glacier's principal stresses or the presence of pre-existing lines of high hydraulic conductivity. If a sufficient supply of water is available, hydrofracturing forms vertical conduits in zones of longitudinal extension and subhorizontal conduits where longitudinal stresses are compressive. On unfractured glacier surfaces, relatively shallow subhorizontal conduits with migrating nickpoints form by cut-and-closure provided channel incision is significantly faster than surface lowering. Conduits can also form along permeable debris-filled crevasse traces that connect supraglacial lake basins of different potential. Our results suggest that Shreve-type englacial drainage systems do not exist and implies that englacial conduits can only penetrate through thick ice to recharge the bed where supraglacial water bodies either intersect, or are advected through, zones of acceleration.

Temperatures and Locations Used by Hibernating Bats, Including Myotis sodalis (Indiana Bat), in a Limestone Mine: Implications for Conservation and Management

Understanding temperatures used by hibernating bats will aid conservation and management efforts for many species. A limestone mine with 71 km of passages, used as a hibernaculum by approximately 30,000 bats, was visited four times during a 6-year period. The mine had been surveyed and mapped; therefore, bats could be precisely located and temperatures (T (s)) of the entire hibernaculum ceiling accurately mapped. It was predicted that bats should hibernate between 5 and 10 degrees C to (1) use temperatures that allow a near minimal metabolic rate, (2) maximize the duration of hibernation bouts, (3) avoid more frequent and prolonged arousal at higher temperatures, (4) avoid cold and freezing temperatures that require an increase in metabolism and a decrease in duration of hibernation bouts or that could cause death, and (5) balance benefits of a reduced metabolic rate and costs of metabolic depression. The distribution of each species was not random for location (P < 0.000) or T (s) (P < 0.000). Myotis sodalis (Indiana bat) was most restricted in areas occupied, hibernating in thermally stable yet cold areas (X = 8.4 +/- 1.7 degrees C); 99% associated with cement block walls and sheltered alcoves, which perhaps dampened air movement and temperature fluctuations. Myotis lucifugus (little brown myotis) hibernated in colder, more variable areas (X = 7.2 +/- 2.6 degrees C). Myotis septentrionalis (northern myotis), Pipistrellus subflavus (eastern pipistrelle), and Eptesicus fuscus (big brown bat) typically hibernated in warm, thermally stable areas (X = 9.1 +/- 0.2 degrees C, X = 9.6 +/- 1.9 degrees C, and X = 9.5 +/- 1.5 degrees C, respectively). These data do not indicate that hibernacula for M. sodalis, an endangered species, should be manipulated to cool below 5 degrees C.

Iron age to medieval entomogamous vegetation and Rhinolophus hipposideros roost in South-Eastern Wales (UK)

Karst cave systems are well developed in Wales (UK) and, in some instances, constitute important bat roosts. Ogof Draenen, near Blaenavon in south-east Wales, is the most recent major cave discovery (1994) with already > 70 km of passages explored spanning a vertical range of 148 m. With the exception of one small chamber (Siambre Ddu) located directly above the main Ogof Draenen system, very few bats have been noticed inside. Extensive accumulations of guano, attributable to Rhinolophus hipposideros, are however found in parts of the Ogof Draenen system. In places covering many square metres and sometimes building heaps > 0.5 m thick, these represent volumes not yet found in any other cave system in the British Isles. Although the date of the abandonment of the main Ogof Draenen system as a bat roost remains unknown, six radiocarbon dates on guano from Ogof Draenen place the occupation in the Iron Age to Medieval period at least. Palynological analysis was undertaken on ten samples distributed through the cave. Comparisons were made with a moss polster and a lake mud sample from the area to provide a first approximation of the regional modern pollen rain and with two modern guano samples, one from Siambre Ddu and one from Agen Allwedd cave (5 km to the north-west) to provide a temporal comparison with the fossil guano. Agen Allwedd cave currently is one of the largest active roosts for Lesser Horseshoe bats in Britain and lies close to the present northern limit of this endangered species in Europe. The main results are that (1) the cave appears to have been used both as a summer and a winter roost; (2) most of the Ogof Draenen guano is formed within c. 1600 14C years and, if the largest heap is continuous, it has accumulated within 750 14C years, i. e. 0.16 mm yr − 1 ; 3) the fossil guano samples reflect a relatively closed oak forest with more abundant ivy ( Hedera) and holly ( Ilex) than at present; (4) insect-pollinated plants such as Ilex, Acer, Hedera and Impatiens glandulifera are over-represented in the guano samples; (5) in addition to the usual causes of bat roost decline (pesticides, pollution), in the case of Ogof Draenen, we may add entrance blocked by rock collapse and decline of the local forest cover as well as change in its composition.

Speleology of gypsum caves in Oklahoma

The gypsum caves of western Oklahoma are situated in three separate areas of evaporite karst: (1) the Cimarron Gypsum Hills, in the northwest, along the Cimarron River; (2) the Weatherford Gypsum Hills, in west-central Oklahoma, to the north of the Wichita Mountains; and (3) the Mangum Gypsum Hills, in the southwest, west of the Wichita Mountains. Caves of the Cimarron Gypsum Hills and the Mangum Gypsum Hills are developed in the alternating dolomite, gypsum/anhydrite, and shale beds of the Permian Blaine Formation. Ranging from natural bridges to extensive cave systems, the largest is the 10km of passages in Jester Cave in the Mangum Gypsum Hills. Cave passages formed in the normally paired gypsum and dolomite beds exhibit narrow (1.5–5 m wide), sinuous, canyon-like profiles. The development of broader passages, with widths from 5 m to more than 35 m, involve the shale beds. Some are bedding-plane passages with extremely low ceilings, whereas others are comfortable, walking-height passages with ceilings from 3–15 m high. The Blaine Formation, in the area of humanly mappable cave development, is from 12 m to approximately 50 m thick. The caves drain the bluffs/escarpments and normally end in karst spring resurgences. Roof collapse often modifies these resurgences into breakdown mazes. The Weatherford Gypsum Hills caves are formed in the Permian Cloud Chief Formation. The Cloud Chief gypsum is chalkier than the Blain gypsums and the resultant cave development is more segmented, ranging from natural bridges (1.5–15 m in length) to cave segments (locally referred to as “tunnels”) that are tens of meters to more than one kilometer in length. These caves exhibit very little vertical development, and none of the bedding-plane development found in the Blaine Formation.

La grotte et le karst de Cango (Afrique du Sud)

CANGO CAVE (SOUTH AFRICA). The author describes a small karst area in the extreme south of the African Continent, with special reference to the Cango Cave , which is a major tourist attraction. Compared with the other karsts of Southern Africa, this area is unique. The karst is typically exogenic, with caves forming by stream disappearance into swallow holes, where the talweg intersects steeply dipping Precambrian limestone. Wet caves are vadose, with only short phreatic segments and exhibit rectilinear longitudinal sections. Passages are low, but wide with bevelled terraced. This peculiar morphology is typical of the caves developing exactly on the water'table and seems to be controlled by the abundance of sediments introduced from the swallow holes. If one excepts a short active lower level, Cango is a dry cave of the same type than the wet ones. It is practically linear in plan and in profile, with a length of 2,6 km from entrance to end for a total of 5,2 km of passages. The age of the speleogenesis has been estimated as early Pleistocene from the entrance elevation, which is in between the altitude of the actual talweg and the one of the Post African I erosion surface, which started to be eroded during the Upper Pliocene. This relatively young age is in contrast with a Miocene model which was accepted by most of the previous authors. Cango is well adorned with speleothems, in particular with outstanding abundant shields, monocrystalline stalagmites and pools coated with calcite crystals. In the first chambers from entrance, the speleothems have been deeply corroded by bat guano, with deposition of hydroxylapatite. Previously this corrosion was attributed to resolution due to several rises of the paleowater -table. The meteorology is discussed, in particular the high carbon dioxide which indicates that the cave is poorly ventilated and which constitutes a problem for management and conservation.

Caves and speleogenesis of Mangaia, Cook Islands

Ten caves in the makatea limestone of Mangaia, Cook Islands were explored and mapped, totalling over 3.7 km of passage. Of these, there was an apparent grouping by elevation that corresponds with previously described sea-level terraces in the makatea. Four caves have major level sections 10-20 m above sea-level, corresponding with a 14.5 m Pleistocene terrace. The high dimensions of these caves indicate downcutting during slow uplift, or multiple reoccupations by highstands of Pleistocene sea­levels. One major cave has level passage 20-30 m above sea-level, corresponding with a 26-27.5 m terrace. Three caves have level passage 40 m above sea-level, corresponding with a m terrace. Active conduit caves are developed at the present sea-level, but are closed with heavy clay deposits from recent soil erosion.

The underground passages and storage pits used in foraging by a nest of the termite Macrotermes michaelseni in Kajiado, Kenya

Part of the system of underground passages and storage pits used in foraging by a nest of Mucrofermes michaelseni was excavated and is described in detail, and an attempt is made to quantify it. Densities as high as 1.9 m of passage and 21.4 storage pits per m2 were recorded in the main foraging zone, which is 10–35 m from the nest. The estimated total for the whole nest was just under 6 km of passage and 72,000 storage pits, in an area of about 8000m2

Caves and Karst of the Hindenburg Ranges

The expedition investigated 2500 km of rugged limestone country in the West Sepik province of Papua New Guinea, between the Strickland Gorge and the Irian Jaya border. The main objectives were the location and mapping of caves in the high altitude karst of the Hindenburg mountains and the study of their biology, hydrology and structure. Two hundred systems were recorded and some were of vast dimensions. One open pit was 280 m deep and descents were made into other shaft systems for 340 m and 360 m. The longest cave located was Selminum Tem, in which 20-5 km of passages were surveyed and the fossil skeleton of a Miocene syrenian was discovered. Three appendices report briefly on the geomorphology, biology and anthropology of the area.