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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. ...

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That elastic properties is the properties describing deformation of a solid [16].?

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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;
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Your search for function (Keyword) returned 275 results for the whole karstbase:
Showing 16 to 30 of 275
Spontaneous and induced acivity patterns in troglobite beetles (Genera Aphaenops, Geotrechus,Speonomus)., 1978, Lamprecht G. , Weber F.
In Constant temperature the troglobite beetles Aphaenops cerberus and pluto, Geotrechus orpheus and Speonomus diecki are aperiodically active. By periodogram analysis neither circadian nor ultradian or infradian periodic components can be found. Moreover there are no relevant correlations between the lengths of successive activity bursts and rest pauses. Consequently the activity patterns are stochasticly structured.; In cases with constancy of activity respectively rest behaviour the probabilities for the transition from activity to rest and from rest to activity are computed using the Frequency histograms of lengths of activity bursts and rest pauses. The transition probability is time-invariant if the observed histogram can be approximated to the negative exponential function. Y=ae -fx . The transition probability increases continuously if the observed histogram can be approximated to the Poisson or normal function. -74% of the investigated frequency histograms of the length of activity bursts and 57% of the histograms of the lengths of rest pauses can be approximated to one of the tested functions. -Aphaenops and Geotrechus specimens do not react to changes of the illumination intensity. Conversely temperature cycles induce distinct activity periodicities. In Aphaenops the mean length of activity bursts is -on the average; less temperature dependent than the mean length of rest pauses. Moreover, in this species the mean length of bursts is weakly negatively correlated with the mean length of pauses.; The evolution and adaptive reactions of the random mechanism of activity control in troglobite animals are discussed.

Locomotor responses of the cave fish Astyanax jordani (Pisces, Characidae) to periodic and aperiodic light and temperature signals., 1978, Thins Georges, Weyers M.
The locomotory activity of adult cave fishes Astyanax jordani was recorded in isolation in the following light and temperature conditions: constant conditions (100 Lx; 200C), in a light cycle (LD:11/11 -10 Lx -100 Lx) and in a temperature cycle (11/11; 17/20, 19/22, 20/23, 27/30 C). All longitudinal time series extended for a minimum of 30 days. Results show: (1) That no circadian regulation appears in constant conditions; (2) that passive entrainment occurs in LD (Amplitude: 90 Lx) and in periodic temperature conditions (Amplitude: 3C). The entrainment effect damps out and varies individually; (3) that the mean activity increases with temperature; (4) The adjustment of activity to periodic signals is individually stable. These results suggest that A. Jordani is devoid of any endogenous oscillator of the circadian type. The observed thermal adaptation could have the following functions: (1) To increase the level of activity in function of the thermal level under the form of passive entrainment; (2) To enhance the exploratory behaviour of the fish in search of a thermal preference allowing the animal to keep inside a well defined zone of the subterranean biotope in relation to small local temperature changes.

Observations on the Biology of Cave Planarians of the United States., 1982, Carpenter Jerry H.
Observations are made on the biology of several species of cave planarians (mostly of the family Kenkiidae) collected alive from over 50 caves in 14 states. Most of these species were maintained in laboratory cultures at 12C3C. Food eaten was extremely variable. Functions of the anterior adhesive organ included food capture, locomotion, defence against predators, and probably chemoreception, mechanoreception, and as a holdfast in strong currents. Predators probably consist of fishes, crayfishes, and salamanders. Sporozoan and ciliated parasites were found occasionally. Cocoons were found in winter, spring, and summer; they hatched in about 3 months and contained 2 to 17 young.

Further Studies At The Blue Waterholes, Cooleman Plain, N.S.W., 1969-77, Part II, Water Chemistry And Discussion, 1983, Jennings, J. N.

The 1969-77 data confirm that groundwater temperature is significantly higher than air temperature at mean catchment altitude but provide only partial support for an explanation in terms of soil temperature and insulation of drainage from cold air ponding over the Plain. Higher pH of output than input streams is attributed mainly to percolation water chemistry. Water chemistry of two contrasted input streams suggests non-karst rock weathering has an important effect on allogenic input streams. An inverse relationship between carbonate hardness and output discharge is found again and attributed mainly to faster transit through the limestone at high flows. Summer has a steeper regression than winter due to precipitation and high flows depressing carbon dioxide and carbonate concentrations more in that season than in winter. Picknett graphs show how solutional capacity varies through the hydrologic system, with aggressive input streams, mainly saturated percolation water, and rarely saturated output springs because of the allogenic component in the last. The total carbonate load of Cave Creek is directly related to discharge, with little seasonal difference so the annual regression is chosen for later calculation. When the carbonate load duration curve and frequency classes for Cave Creek are compared with those for other karsts, it falls into an intermediate class in which neither very high nor low flows dominate the pattern. This is attributed to a combination of a large allogenic input with a complex routing pattern. Consideration of most input stream solute concentration on one occasion indicates such close dependence on catchment geology that doubt is cast on the smallness of the 1965-9 allocation of carbonate contribution from non-karst rock weathering to the allogenic input. This is explained by new CSIRO rainfall chemistry figures from the Yass R. catchment which are smaller than those used before and by elimination of a previous error in calculation. This time subtraction of atmospheric salts is done on a daily basis with a decaying hyperbolic function. Correction of Cave Creek output for allogenic stream input follows the method adopted in 1965-9 but on a firmer basis, with the assumption of approximately equal water yeild per unit area from the non-karst and karst parts of the catchment being more factually supported than before. It remains a substantial correction. The correction for subjacent karst input to Cave Creek is also improved by putting the calculation in part on a seasonal basis; it remains small. The exposed solute load output shows the same seasonal pattern as was determined earlier, with a winter/spring maximum, and it again evinced much variation from year to year. So did annual rates. The mean annual loss of 29 B was slightly greater than for 1965-9. If this difference is real and not an experimental error, the reduced allowance for atmospheric salts and greater annual rainfall in the second period could explain the increase. This erosion rate of 29 B from an annual runoff of about 400mm places this karst where it would be expected in the world pattern of similar determinations in terms of both runoff and its proximity to the soil covered/bare karst dichotomy of Atkinson and Smith (1976). Combined with the other work at Cooleman Plain on erosion at specific kinds of site, an estimate of the spatial distribution of the limestone solution is presented. It agrees well with the similar attempt for Mendip by Atkinson and Smith (1976), when allowance is made for certain differences in method and context. The main conclusions are the great role of solution in the superficial zone and the unimportance of the contribution from caves. Conflict between this process study and the geomorphic history of Cooleman Plain remains and once again an explanation is sought in long persistence of a Tertiary ironstone cover inhibiting surface solution.


Le karst du compartiment oriental de la basse Cvenne carbonate (Gard), 1988, Martin, Ph.
The karst of the Eastern compartment of the carbonated Lower Cvenne (Gard) - This text summarises 10 years of exploration and study of the eastern karst of the Gardon river basin above Als. Karst concerns 5 facies: Trias, Hettangian-Sinemurian (rich in limonite and pyrites), Upper Bajocian - Lower Bathonian (rich in pyrites), Upper Jurassic and Barremian. This lager is broken into more or less rolling panels, which have collapsed towards the Als rift. Tridimensional systems draining this karst are considered to be evolving toward better performance. It is a remarkable case of natural organisation. Structure is deduced from function. A morphologic approach explains the systems history. Three of the four identified karstic systems are simple. They are partial a natural models of the fourth: the Fonts karstic system. We describe on detail some elements of its structure (caves for ex.) and of its functio-ning (hydrodynamic, hydrochemistry). We show through pumping that the Cauvel river feeds the Fonts spring and the Carabiole spring. The effect of geological and geomorphologic characteristics of the spring site on water output is mentioned. We describe the realisation of a pumping station driving subterranean Cauvel river water a 100m back and point out the usefulness of speleological information.

Civil engineering difficulties in the karst of China, 1988, Waltham A. C. , Smart P. L. ,
Karst landscapes, developed by solutional erosion of massive limestones, are characterized by underground drainage and the development of closed depressions. In tropical areas, with high solution rates, long uninterrupted periods of erosion and a lack of glacial planation, the expansion and deepening of these closed depressions creates a rugged relief dominated by either conical hills or steeper-sided towers. The form of the cones and towers is a function of both the carbonate lithology and the erosional history; the towers develop only in massive, mechanically strong, compact limestones where erosional planation and tectonic uplift have kept pace over a long period of time (Smart et al 1986). These karst landscapes are characteristic of huge areas of southern China, largely in the provinces of Guangxi and Guizhou (Fig. 1) and the spectacular scenery of the limestone has often been represented in classical Chinese painting. They are now also becoming a major tourist attraction, with Guilin, in Guangxi, frequently visited by Westerners. These terrains do, however, pose serious difficulties to the civil engineer. Where relief is not great, or where rates of uplift have been low, corridors of flatter ground have often been created by lateral planation at the water table. These corridors may be lithologically or structurally controlled, and form obvious routes through the karst. Where the relief is higher and the regional water table is not intersected, coalescence of the depressions to form flatter ground is rare, and road and rail development is more problematic. In order to avoid excessive and ... This 250-word extract was created in the absence of an abstract

Ultrastructure des sensilles cylindriques, mcanorcepteurs d'un Crustac Mysidac souterrain., 1990, Crouau Yves
The ultrastructural features of a new chordotonal sensillum in a cavernicolous Mysidacea is described. That sensillum and the other mechanoreceptor sensilla of the same Mysidacea are compared. 9 + 0 cilia show ultrastructural features which previously allowed us to establish a hypothesis with respect to the mode of functioning of chordotonal sensilla. That sensillum shows a pore at the tip of its external receptor.

RHYTHMIC KARST SPRINGS, 1991, Bonacci O, Bojanic D,
Rhythmic springs (ebb and flow springs, intermittent springs, potajnice) belong to the group of springs which appear exclusively in karstified terrains. The paper describes various types of rhythmic springs and gives their classification. It also develops a mathematical model for the functioning of this type of springs based on the principle of recharge and emptying of the underground reservoir through siphon action. Applying this model, according to the observed hydrographs of some rythmic springs in Yugoslavia, the paper explains in detail the structure of the underground reservoir located in the karst

Karst hydrogeology of the Canadian Rocky Mountains, PhD Thesis, 1991, Worthington, Stephen Richard Hurst

An analysis of the discharge and hydrochemical variations of contrasting springs at Crowsnest Pass showed they were part of a vertical hierarchy in the aquifer, in which underflow and overflow components play a dominant role. It was found that karst springs at Crowsnest Pass and elsewhere show a range between two end members. Thermal springs have long, deep flow paths, with high sulphate concentrations, low discharge variance and low flow velocities. Overflow springs have local shallow flow paths, low sulphate, high discharge variance, and high flow velocities. Intermediate between these end members are underflow springs; in the Rocky Mountains these are mostly aggraded, and give the sustained winter flow and high sulphate concentrations found in major rivers. It was found that underflow or overflow behaviour is able to explain most of the contrasts found between karst springs in discharge and sulphate concentrations. Conversely, differences in bicarbonate concentration are principally due to the ratio of allogenic to autogenic recharge to the aquifer. Hydraulic analysis showed that gradients decrease in the downstream direction, and are typically 0.0001-0.05 at maximum discharges, that friction factors vary by a factor of $>$1000, and that most active conduits have closed-channel flow and are in dynamic equilibrium with sediment supply. The analysis of the hydrological data from Crowsnest Pass and elsewhere has led to the development of a new conceptual model for groundwater flow in karst, in which the Hagen-Poiseuille flow net conditions the aquifer for conduit development, and determines where the conduits will be. The model explains why most conduits are in dynamic equilibrium with sediment supply, why temperate karst springs are mostly vauclusian, what the mean time for speleogenesis is, how $>$98% of the solution of limestone is in the surficial zone, and why there are karstic hot springs in the Rocky Mountains and elsewhere. The model enables predictions to be made of sink to resurgence flow velocities, of conduit depth below the water table, of the ratio of beds to joints used by conduits, of the spacing between cave tiers, and of the depth of vauclusian springs. This new understanding of how karstic aquifers develop and function gives a powerful predictive ability to karst hydrogeology.


Archaeoastronomical Identification of the Functional Elements in the Rocky-Cave Sanctuary Connected with Ancient Cult Toward the Moon on Bulgarian Land, 1992, Stoev Alexey, Stoytchev Todor

WATER-BUDGET, FUNCTIONING AND PROTECTION OF THE FONTAINE-DE-VAUCLUSE KARST SYSTEM (SOUTHEASTERN FRANCE), 1992, Blavoux B, Mudry J, Puig Jm,
The karst aquifer of the well-known Fontaine de Vaucluse has been recently studied, results have been got about delimitation of the system and its working. Geological data (lithology and structure) have allowed to delimit an 1115 Km2 intake area including Ventoux-Lure north facing range (1,909-1,826 m) and the Plateau which is prolonging it southwards (Fig. 1 and 2). The average altitude of the whole area, obtained by balancing elevation belt surfaces, is about 870 m. This elevation squares with results of tracing tests (Fig. 3), environmental physical, chemical and isotopic tracings, that allow to value a 850 m average altitude for the intake area (Fig. 4). The moisture balance has been computed from an altitude belts climatic model, using local rain an temperature gradients (Fig. 5 and Table II), because the weather network is not representative. So, rainfalls rise of about 55 mm per 100 m elevation and temperature decreases of about 0.5-degrees-C per 100 m. The consequence of these two antagonist phenomena is the quasi constant value of actual evapotranspiration on each altitude belt. With the Fig. 7 organigram, curves of effective rainfalls and infiltration coefficient versus elevation can be plotted (Fig. 6). This computation shows that 3/4 of the total and the whole of dry season effective rainfalls are provided by the part of the intake area situated above the average altitude: on the lowest belt, effective rainfalls are only 120 mm per year and increase to 1380 mm on the upper section (Fig. 8 and Table 1). The weighted effective rainfalls are about 570 mm per year for the whole intake area. Hydrodynamical and physico-chemical studies show, despite its large size, the weak inertia of the system, so proves its good karstification, that confirms for the whole system the pin-point speleological observations. The discharge of the spring, which average value is 21 m3.s-1 (only 18 for the last ten years), can exceed 100 m3.s-1 and the minimum has never been lower than 3.7 m3.s-1 (Fig. 9). When it rains on the intake area, the increase of the discharge is very sudden in a rainy period : one to four days. This short delay is due to seepage through epikarst and unsaturated zone. During dry periods, the spring reaction is deadened, due to storage in the unsaturated zone. The silica content distribution was plotted during several hydrokinematical phases (Fig. 10). It shows: an almost unimodal distribution for the 8 km2 fissured limestone aquifer of Groseau; a multimodal one for the 1115 km2 karst aquifer of Fontaine de Vaucluse. This proves that karstification is more important than size in the response of the system. Weak summer rainfalls do not influence the discharge, nevertheless they influence chemistry of the spring water, and so interrupts the water depletion phasis. Then, the decrease of discharge can continue after the end of the chemical depletion phasis, water which is overflowing after summer rainfalls (in a dry period) is influenced hy the chemistry of seepage water : on the graph of a principal components analysis, done on chemical variables. an hysteresis phenomenon can be seen (Fig. 11). A discriminant analysis (Fig. 12) confirms that these autumn waters, with high ratio seepage tracers, are not reserve waters from the saturated zone. The ratio of reserve water in the total discharge, is preponderant: 3/4 and 2/3 respectively of the yearly runoff volumes for 1981 and 1982 (Fig. 13), but an important part of these reserves can be stored in the unsaturated zone. This storage capacity can be valued by different means: transposing to Vaucluse (1115 km2) the volume measured on another karst system in the Pyrenees (13 km2); it gives about 100 million m2; using setting parameters of Bezes model (1976) on the same aquifer: it gives 113 million m3; using depletion curves, that show, for instance during the 1989 summer and autumn dry period, a 80 million m3 volume. In all cases, we get a value of about one hundred million m3 for the storage capacity of the unsaturated zone. With a 20 m range of fluctuation for the water table and with a 10(-2) specific yield, on a 500 to 1,000 km2 saturated zone, the zone of fluctuation can release about 10 to 20 million m3. Then, the volume of water stored in the whole saturated zone, with a 300 m minimum thickness (depth of the waterlogged pit of the Fontaine), a 500 km2 minimum surface and a 10(-3) specific yield, is about 150 million m3, including 27 million m3 stored in the channels. So, the unsaturated zone represents a significant part of the whole storage capacity and most of the yearly renewable reserves. Paradoxically, the biggest french spring is not tapped at all; as its intake area is neither a regional nor a national park, no general protection covers it : because of its good karstification, the vulnerability of the system is important. Good quality of water is attributable to the low population and human activities density on the intake area (4 inh.km-2). A great part of the intake area is uncultivated (large forest and ''garrigues'' areas). Due to the lack of surface water and scantness of soils, agriculture is not intensive (lavender, thyme, sage and bulk wheat fields. meadowlands). On the mountainous zone, roads are salted in winter and snowmelt water can reach a significantly high chloride ratio than in a natural climatic functioning (for instance 25 mg.l-1 in Font d'Angiou where the ratio would have been 3 mg.l-1). As tourism is developing both on the mountain and on the plateau, the management of the highest intake area must be carefully held: its part is preponderant in the feeding of the system

EXPLORATION AND DEVELOPMENT OF GROUND-WATER FROM THE STONE FOREST KARST AQUIFERS OF SOUTH CHINA, 1992, Huntoon P. W. ,
Stone forest aquifers are the most widely exploited sources for ground water in the vast south China karst belt. These aquifers occupy a thin epikarst zone that has been infilled with clastic sediments. The aquifers are characterized by large lateral permeabilities and small reservoir capacities owing to their thinness. The carbonate rocks which comprise the framework for the aquifers are usually buried under the karst plains and large karst depressions where development is desired. The stone forest aquifer exploration procedure must first locate saturated zones. Second, those parts of the saturated zone having the greatest dissolution porosity must be identified because the infilled dissolution voids contain the water. The best indicators of saturation include the combination of low topography and the presence of active karst features such as springs, karst windows (natural openings exposing the water table), and live surface streams. These elements are readily observed on intermediate scale (1:20,000) aerial photography. The depth and degree of carbonate dissolution porosity is a function of several geologic and hydrologic factors including carbonate rock type, carbonate purity, fracture density, specific discharge, age of the circulation system, etc. These variables cannot be measured directly because the carbonate rocks are usually buried under a thin mantle of clastic sediments. However, if it is recognized that the ground-water system has already exploited the most favorable geology and that dissolution is an ongoing process, a simple indirect method can be used to identify the areas having the greatest porosity. The presence of karst depressions and recent sinkholes are indicative of the most intensely karstified and hydraulically active parts of the epikarst zone. Mapping of these surface features from stereo aerial photography is a simple geomorphology exercise that can be used to directly identify the most favorable well sites. Current well construction practices in the south China karst belt involve both dug and drilled wells. Dug wells are preferred in many locations owing to both cost-effectiveness associated with cheap labor and lack of available drilling equipment. The dug wells look and function identically to karst windows and thus conform to timeless water use traditions in the region

THE VRANA LAKE HYDROLOGY (ISLAND OF CRES - CROATIA), 1993, Bonacci O,
The Vrana Lake on the island of Cres in the Adriatic Sea represents a specific phenomenon of karst hydrology. The island of Cres covers an area of 404.3 km2 with an average volume, of 220 x 10(6) m3 of fresh water in the lake. The island has an average rainfall of 1,063 mm, with a Mediterranean climate. The lake has a bottom reaching a depth of 62 m below mean sea level. The average water level is 14 m above mean sea level. The most probable theories on the origin of the lake and its hydrologic-hydrogeologic functioning state that it is a flooded polje in karst. The water budget method was used to define the lake catchment area at approximately 25 km2. During the last six years, there has been drastic decrease of about 3 m in the lake's water level. This phenomenon was analyzed and it was calculated that 53 percent of the water-level decline was caused by water discharges from the lake to satisfy water supply demands, and 47 percent was due to a period of low precipitation during the analyzed period

Towards regressive evolution: the periodic colour change behaviour of a troglophilic fish Nemacheilus evezardi (Day), 1994, Biswas Jayant, Pradhan Rohit K.
Present study is an attempt to know the existence of colour change physiology of the cave fish Nemacheilus evezardi (Day) along a circadian time scale. Though, due to subterranean mode of life, practically this function has no survival value. The study has been conducted simultaneously in two different photoperiodic conditions (LD 00: 24 and LD 12:12 hr). The variation in different states of chromatophore has been computed with respect to different time points of the day. Results suggest that the phenomenon is lying completely disturbed in its in situ conditions. Interestingly, circadian rhythm in all the types of chromatophores were validated when the same fish was exposed under LD 12: 12 hr photoperiod.

The astronomical theory of climate and the age of the Brunhes-Matuyama magnetic reversal, 1994, Bassinot Fc, Labeyrie Ld, Vincent E, Quidelleur X, Shackleton Nj, Lancelot Y,
Below oxygen isotope stage 16, the orbitally derived time-scale developed by Shackleton et al. [1] from ODP site 677 in the equatorial Pacific differs significantly from previous ones [e.g., 2-5], yielding estimated ages for the last Earth magnetic reversals that are 5-7% older than the K/Ar values [6-8] but are in good agreement with recent Ar/Ar dating [9-11]. These results suggest that in the lower Brunhes and upper Matuyama chronozones most deep-sea climatic records retrieved so far apparently missed or misinterpreted several oscillations predicted by the astronomical theory of climate. To test this hypothesis, we studied a high-resolution oxygen isotope record from giant piston core MD900963 (Maldives area, tropical Indian Ocean) in which precession-related oscillations in [delta]18O are particularly well expressed, owing to the superimposition of a local salinity signal on the global ice volume signal [12]. Three additional precession-related cycles are observed in oxygen isotope stages 17 and 18 of core MD900963, compared to the composite curves [4,13], and stage 21 clearly presents three precession oscillations, as predicted by Shackleton et al. [1]. The precession peaks found in the [delta]18O record from core MD900963 are in excellent agreement with climatic oscillations predicted by the astronomical theory of climate. Our [delta]18O record therefore permits the development of an accurate astronomical time-scale. Based on our age model, the Brunhes-Matuyama reversal is dated at 775 10 ka, in good agreement with the age estimate of 780 ka obtained by Shackleton et al. [1] and recent radiochronological Ar/Ar datings on lavas [9-11]. We developed a new low-latitude, Upper Pleistocene [delta]18O reference record by stacking and tuning the [delta]18O records from core MD900963 and site 677 to orbital forcing functions

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