the decay of coastal forts in southeast brazil and its implications for the conservation of colonial built heritage the 500th anniversary of european arrival in brazil was celebrated in 2000 and highlighted the need to review the condition of the country s remaining colonial built heritage this revision is particularly apposite in the adjacent cities of rio de janeiro and niteroi where the heritage that survived twentieth century reconstruction has done so largely because of ownership by the church or military however whilst this may have protected buildings from demolition detailed fabric can be neglected or abused this paper investigates this possibility through an examination of two forts built primarily of local augen gneiss that guard the entrance to guanabara bay natural outcrops exposed to the same humid sub tropical maritime environment show that this rock is susceptible to slow disaggregation through salt weathering surveys suggest that stonework in the forts that is sheltered from rainwash is heavily loaded with salt and has passed a threshold wherein stresses accumulated over centuries of apparent stability combined with the effects of a more recent increase in atmospheric pollution and apparently inappropriate intervention re pointing have triggered rapid breakdown that requires immediate intervention

modeling flow in phreatic and epiphreatic karst conduits in the holloch cave muotatal switzerland the holloch cave is a site where the hydrodynamic behavior of a karst conduit network can be observed with a high degree of precision observed heads discharge rates conduit sizes and conduit lengths have been compiled into a simple hydrodynamic model in order to check their consistency it was possible to calibrate and satisfactorily fit the observed data model results show the following 1 flow models which are able to simulate turbulent flow in variably saturated conduit networks can adequately model conduit flow dominated karst systems 2 karst systems may be strongly nonlinear especially because of the presence of epiphreatic conduits 3 under certain circumstances storage in the epiphreatic conduits and in the fissured limestone matrix can be neglected 4 the typical effective hydraulic conductivity of karst conduits ranges between 1 and 10 m s 1 and the louis formula is adequate to calculate head losses in those conduits 5 indirect measurements of flow velocity using scallop size indicate values of 30 40 of the maximal annual discharge and velocity derived from pebble size indicates values of 150 of the maximal annual discharge

sediment transport during recent cave flooding events and characterization of speleothem archives of past flooding abstract extreme precipitation events have a disproportionate impact on landscape evolution and on human constructions and the frequency and intensity of extreme events may vary with changes in mean climate in the past and in the future we document the potential for cave sediment archives to record past changes in the frequency of flooding events by characterizing the modern processes responsible for sediment deposition and mobilization during floods and linking these to their incorporation in speleothem deposits we focus on the cueva fria cave system in nw spain which like other caves in the region features abundant sandy sediments sourced from dominant sandstone lithologies in the catchment area in this case delineated by our dye trace study in this system the extreme flood conditions in june 2010 caused overflow of the cave stream and deposition of nearly 1 m of sand in sectors near the cave stream and resulted in burial of some stalagmites in 30 cm of sand in more distal sectors all sectioned stalagmites growing

varied response of western pacific hydrology to climate forcings over the last glacial period atmospheric deep convection in the west pacific plays a key role in the global heat and moisture budgets yet its response to orbital and abrupt climate change events is poorly resolved here we present four absolutely dated overlapping stalagmite oxygen isotopic records from northern borneo that span most of the last glacial cycle the records suggest that northern borneo s hydroclimate shifted in phase with precessional forcing but was only weakly affected by glacial interglacial changes in global climate boundary conditions regional convection likely decreased during heinrich events but other northern hemisphere abrupt climate change events are notably absent the new records suggest that the deep tropical pacific hydroclimate variability may have played an important role in shaping the global response to the largest abrupt climate change events

source process and tectonic implications of the great 1975 north atlantic earthquake summary the atlantic segment of the africa europe plate boundary has usually been interpreted as a transform boundary on the basis of the bathymetric expression of the gloria fault and dextral strike slip first motion mechanisms aligned along the azores gibraltar line of seismicity the 1975 may 26 earthquake ms 7 9 was assumed to fit into this framework because it occurred in the general area of this line and has a similar first motion focal mechanism strike 288 dip 72 slip angle 184 however several anomalies cast doubt on this picture the event is abnormally large for an oceanic transform event a sizeable tsunami was excited the aftershock area is unusually small for such a large event and most significantly the epicentre is 200 km south of the presumed plate boundary the rayleigh wave radiation pattern indicates a change in focal mechanism to one with a significant dip slip component the short duration of the source time history 20 s as deconvolved from long period p waves the lack of directivity in the rayleigh waves and the small one day aftershock area suggest a fault length less than 80 km one nodal plane of the earthquake is approximately aligned with the trace of an ancient fracture zone we have compared the pasadena 1 90 record of the 1975 earthquake to that of the 1941 north atlantic strike slip earthquake 200km to the nnw and confirmed the large size of the 1941 event m 8 2 the non colinear relationship of the 1975 and 1941 events suggests that there is no well defined plate boundary between the azores and gibraltar this interpretation is supported by the intraplate nature of both the 1975 event and the large 1969 thrust event 650 km to the east this study also implies that the largest oceanic strike slip earthquakes occur in old lithosphere in a transitional tectonic regime

sediment discharges during storm flow from proximal urban and rural karst springs central kentucky usa summary since the mid 1990s various studies have addressed the timing of sediment transport to karst springs during storm flow or the composition and provenance of sediment discharged from springs however relatively few studies have focused on the flow thresholds at which sediment is mobilized or total sediment yields across various time scales we examined each of these topics for a mainly urban spring blue hole and a rural spring sp 2 in the inner bluegrass region of central kentucky usa suspended sediment consisted mostly of quartz silt and sand with lesser amounts of calcite and organic matter total suspended sediment tss values measured during storm flow were greater at sp 2 than at blue hole by aggregating data from four storms during 2 years we found that median suspended sediment size jumped as q exceeded 0 5 m 3 s for both springs at blue hole tss tended to vary with q and capacity approached 1 g l but no systematic relationship between tss and q was evident at sp 2 sediment fluxes from the blue hole basin were 2 orders of magnitude greater for storms in march 2002 and 2004 than september 2002 and 2003 in contrast sediment fluxes from the sp 2 basin were of similar magnitude in september 2003 and march 2004 the overall range of area normalized fluxes for both springs 9 16 10 3 4 45 10 2 kg ha h overlaps values reported for farm plots and a stream in the inner bluegrass region and for other spring basins in the eastern usa and western europe sediment compositions sizes and responses to storms in the basins may differ because of land use e g the extent of impervious cover in the blue hole basin basin size larger for blue hole conduit architecture which appears to be more complex in the blue hole basin and the impoundment of sp 2 which may have promoted decadal scale storage of sediment upgradient

three thousand years of extreme rainfall events recorded in stalagmites from spring valley caverns minnesota article i nfo annual layer analysis in two stalagmites collected from spring valley caverns southeastern minnesota reveals hydrological response of the cave to extreme rainfall events in the midwest usa cave flooding events are identified within the two samples by the presence of detrital layers composed of clay sized particles comparison with instrumental records of precipitation demonstrates a strong correlation between these cave flood events and extreme rainfall observed in the upper mississippi valley a simple model is developed to assess the nature of rainfall capable of flooding the cave the model is first calibrated to the last 50 yr 1950 1998 a d instrumental record of daily precipitation data for the town of spring valley and verified with the first 50 yr of record from 1900 to 1949 a d frequency analysis shows that these extreme flood events have increased from the last half of the nineteenth century comparison with other paleohydrological records shows increased occurrence of extreme rain events during periods of higher moisture availability our study implies that increased moisture availability in the midwestern region due to rise in temperature from global warming could lead to an increase in the occurrence of extreme rainfall events

stratigraphic evidence for a pluvial phase between ca 8200 7100 ka from renella cave central italy a stratigraphic and chronological study of the upper level of renella cave apuan alps central italy reveals that two episodes of flowstone accumulation bracket a thick clastic layer deposited between ca 8 2 and 7 1 ka this layer which represents a period of enhanced cave flooding is substantially in phase with an interval of depleted oxygen isotope values previously recorded in a stalagmite from nearby corchia cave interpreted to have resulted from an increase in local precipitation these data confirm that during this period of time the region experienced relatively wetter conditions including an increase in high magnitude events capable of invading the higher passages of renella cave the timing of the clastic phase occurred when the eastern mediterranean experienced deposition of sapropel layer s1 which is thought to reflect the stagnation of sea water produced largely by enhanced flood activity along the nile in response to increased monsoon intensity in northern equatorial africa recent estimates suggest that s1 may have lasted from ca 10 8 to ca 6 1 ka cal bp combined evidence from renella and corchia cave indicates that the period corresponding to the wettest phase in the apuan alps was much shorter than this and suggests that there is no straightforward connection between increased advection of water vapour from the atlantic between 8 2 and 7 1 ka as recorded in the corchia and renella records and monsoon driven enhancement of nile discharge and s1 deposition in the eastern mediterranean

speleothems as high resolution paleoflood archives abstract over the last two decades speleothems have become widely utilized records of past environmental variability typically through their stable isotopic and trace elemental chemistry numerous speleothem researchers have identified evidence of flooding recorded by detrital layers trapped within speleothems but few studies have developed paleoflood reconstructions from such samples because they can be precisely dated are generally immune to post depositional distortion or erosion and can be tied to a fixed elevational baseline speleothems hold enormous potential as high resolution archives of cave floods and thus as proxies for extreme rainfall or other hydrologic drivers of cave flooding here we review speleothem based paleoflood reconstruction methods identify potential biases and pitfalls and suggest standard practices for future studies

calcite fabrics growth mechanisms and environments of formation in speleothems from the italian alps and southwestern ireland five fabrics were identified in alpine and irish caves on the basis of morphological and microstructural characteristics and re lated to growth mechanisms and growth environment columnar and fibrous fabrics grow when speleothems are continuously wet and from fluids at near equilibrium conditions low supersaturation sicc 0 35 through the screw dislocation mechanism the highly defective microcrystalline fabrics form at the same supersaturation range as co lumnar fabric but under variable discharge and the presence of growth inhibitors dendritic fabrics which have the highest density of crystal defects develop in disequilibrium conditions high supersaturation un der periodic very low flow regime periods that result in prolonged out gassing cave calcareous tufa forms in disequilibrium conditions only the calcite crystals of fabrics formed at low supersaturation seem to precipitate near isotopic equilibrium conditions

new data on speleothem deposition and palaeoclimate in britain over the last forty thousand years 230th 234u dates are presented for 26 speleothems from three areas in britain assynt n w scotland n w yorkshire mendip hills somerset these dates suggest that speleothem growth was widespread but rare in the period from 40 to 26 ka absent from 26 to 15 ka and abundant from 15 ka to the present the absence of speleothems between 26 and 15 ka is attributed to glaciation in yorkshire and assynt and tentatively to continuous permafrost development in the mendip hills the occurrence of speleothems before 26 ka places restrictions on the extent of any ice sheet which may have been present in scotland and indicates that n w scotland was not subjected to continuous permafrost at that time

trace elements in speleothems as recorders of environmental change speleothems are now established as important palaeoenvironmental archives and contain a number of suitable proxies although trace elements have been much less widely used than oxygen and carbon isotopes the complexity of the cave environment helps to explain this since the fluids from which speleothems form vary greatly in composition in space even within a cave chamber seasonally and over longer periods understanding the forcing factors for this variability is the key to decoding the significance of the trace element records a variety of techniques are available for trace element work and it is important to understand the strengths and limitations of each and also to seek an understanding e g by micro imaging techniques of whether the elements are associated with inclusions in the caco3 or are isolated within the crystal lattice for some elements there is a more or less predictable relationship between element ratios to ca in the water and in the calcite individual trace elements may be derived from atmospheric deposition superficial deposits or bedrock and can be recycled in soil processes before being transferred to the cave some components show an instantaneous response to water infiltration whereas others are only leached by slow flowing seepage waters changing in the proportion of water from fracture fed and seepage flow aquifer compartments is an important factor in influencing trace element supply high flows lead to higher fluxes of soil derived colloidally transported elements conversely under relatively dry conditions degassing of co2 results in prior calcite precipitation upflow of the site of speleothem deposition and leads to higher ratios of sr ca and mg ca some trace element variations in speleothems over time are induced during crystal growth whereby faster growth leads to a greater departure from equilibrium element partitioning despite the demonstrated temperature dependence of mg partitioning into calcite attempts at deriving palaeotemperature records from speleothems have been so far confounded by variations in solution mg ca and or crystallographic effects a number of case studies have effectively used trace elements such as speleothem mg as records of palaeo aridity using supporting arguments from modern monitoring or covariations with other parameters such as stable isotopes sr and u isotopes can also be indicators of palaeohydrology although sr isotope variations can also reflect varying aeolian input considerable progress has been made in decoding the meaning of annual trace element variations using criteria for understanding dripwater hydrology and ph this should lead in the future to more specific interpretations of how seasonality evolves through time

late holocene annual growth in three alpine stalagmites records the influence of solar activity and the north atlantic oscillation on winter climate annual growth rates and the ratio of dark to light colored calcite within single annual laminae in three contemporaneously deposited holocene speleothems from grotta di ernesto an alpine cave in northern italy respond to changes in surface temperature rather than precipitation based on monitoring of present day calcite growth and correlation with instrumental data for surface climatic conditions we interpret a higher ratio of dark to light colored calcite and the simultaneous thinning of annual laminae as indicative of colder than present winters such dark and thin laminae occur in those parts of the three stalagmites deposited from ad 1650 to 1713 and from ad 1798 to 1840 as reconstructed through lamina counting these periods correspond to the well known maunder and dalton minima of solar activity an 11 yr cyclicity in growth rate coupled with reduced calcite deposition during the historic minima of solar activity is indicative of a solar influence on lamina thickness spectral analysis of the lamina thickness data also suggests that the north atlantic oscillation variability influenced winter temperatures based on the present day controls on cave calcite formation we infer that high frequency changes in solar activity modulated the seasonal duration of soil co2 production

a test of annual resolution in stalagmites using tree rings abstract so called annual banding has been identified in a number of speleothems in which the number of bands approximates the time interval between successive u series dates the apparent annual resolution of speleothem records however remains largely untested here we statistically compare variations in band thickness from a late holocene stalagmite in carlsbad cavern southern new mexico usa with three independent tree ring chronologies form the same region we found no correspondence although there may be various explanations for the discordance this limited exercise suggests that banded stalagmites should be held to the same rigorous standards in chronology building and climatic inference as annually resolved tree rings corals and ice cores

evidence of inception horizons in karst conduit networks this paper outlines the conclusion from an analysis of 18 large cave systems around the world comprising more than 1500 km of conduits the 3d geometry of complex cave systems have been analysed in relation to their geological context as well as their hydrogeological boundary conditions the methodology allowed for the first time statistical evidence of the inception horizon concept thereby it confirms that the development of karst conduits under phreatic conditions is strongly related to a restricted number of so called inception horizons an inception horizon is a part of a rock succession that is particularly susceptible to the development of karst conduits because of physical lithological or chemical deviation from the predominant carbonate facies within the limestone sequence it passively or actively favours the localisation of dissolutional voids

uranium series dating of marine and lacustrine carbonates of the possible uranium series dating schemes the most important and most widely applied to marine carbonates is 230th dating with 231pa dating playing an increasingly important role for this reason this review will focus on these two methods 230th dating also referred to as u th dating or 238u 234u 230th dating involves calculating ages from radioactive decay and ingrowth relationships among 238u 234u and 230th 232th is also typically measured as a long lived essentially stable index isotope over the time scales relevant to 230th dating at present 230th dating can in principle be used to date materials as young as 3 years and in excess of 600 000 years edwards et al 1987a 1993 edwards 1988 see stirling et al 2001 for an example of dating corals in excess of 600 000 years old 231pa dating also referred to as u pa dating involves calculating ages from the ingrowth of 231pa from its grandparent 235u at present 231pa dating can be used to date materials as young as 10 years and as old 250 000 years edwards et al 1997 230th dating covers all of the 231pa time range and more with somewhat higher precision and is therefore the method of choice if a single method is applied however the combination of 231pa and 230th dating is of great importance in assessing possible diagenetic mobilization of the pertinent nuclides and thereby the accuracy of the ages allegre 1964 ku 1968 even if the primary age exceeds the 250 000 year limit of 231pa dating the combined methods can be used to assess the degree to which the samples have remained closed over the past 250 000 years e g edwards et al 1997 thus

environmental controls on the petrology of a late holocene speleothem from botswana with annual layers of aragonite and calcite abstract a carbonate stalagmite from drotsky s cave in northwestern botswana consists of alternating layers of calcite and aragonite layer counts and radiocarbon ages indicate that the calcite aragonite pairs are annual layers representing about 1500 years of deposition the annual layering probably resulted from highly seasonal rainfall comparison of the uppermost layers of the speleothem with meteorological records shows that precipitation of caco3 in drotsky s cave was controlled by climate thickness of calcite layers correlates with rainfall suggesting that calcite precipitation was largely dependent on the quantity of water supplied to the speleothem by contrast thickness of aragonite layers correlates with temperature although variation in temperature cannot explain greater aragonite abundance on the sides of the speleothem compared to its center mg ca ratios in calcite layers increase upward to the bases of overlying aragonite layers and analyses of cave waters suggest that fluid mg ca ratios reach levels sufficient to cause aragonite precipitation increasing evaporation which caused greater ionic strength and supersaturation resultant increasing mg ca ratios in the fluid and perhaps increasing temperature probably combined to cause aragonite precipitation detailed petrographic analysis suggests that each annual cycle of caco3 precipitation began with relatively intense fluid flow sometimes sufficient to dissolve some of the underlying aragonite before precipitation of calcite calcite precipitation under a thick fluid layer allowed euhedral crystals to form at first but thinning of the fluid to a film allowed only flatly terminated calcite crystals by season s end as fluid flow diminished increasing evaporation increasing mg ca ratios in the fluid and perhaps increasing temperature combined to cause aragonite precipitation to begin particularly on the sides of the speleothem in some years fluid flow diminished to the point that dust accumulated on aragonite surfaces before the onset of the next year s precipitation p

speleothem evidence for late holocene climate variability and floods in southern greece abstract we present stable isotope data 18o 13c from a detrital rich stalagmite from kapsia cave the peloponnese greece the cave is rich in archeological remains and there are reasons to believe that flooding of the cave has directly affected humans using the cave using a combination of u th and 14c dating to constrain a site specific correction factor for 232th 238u detrital molar ratio a linear age model was constructed the age model shows that the stalagmite grew during the period from ca 950 bc to ca ad 830 the stable oxygen record from kapsia indicates cyclical changes of close to 500 yr in precipitation amount with rapid shifts towards wetter conditions followed by slowly developing aridity superimposed on this signal wetter conditions are inferred around 850 700 500 and 400 100 bc and around ad 160 300 and ad 770 and driest conditions are inferred to have occurred around 450 bc ad 100 150 and ad 650 detrital horizons in the stalagmite indicate that three major floods took place in the cave at 500 bc 70 bc and ad 450 the stable carbon isotope record reflects changes in biological activity being a result of both climate and human activities

speleothem deposition at the glaciation threshold an attempt to constrain the age and paleoenvironmental significance of a detrital rich flowstone sequence from entrische kirche cave austria abstract proxy records from high altitude locations predating the last glacial maximum are rare but could provide invaluable insights into the response of alpine catchments to the rapid climate fluctuations which characterized the last glacial period here we present a detrital rich flowstone record from entrische kirche cave an inneralpine cave situated close to the accumulation area of the pleistocene ice stream network of the european alps that expanded repeatedly into the lowlands during glacial maxima u th dating of this calcite is challenging due to high detrital th however petrographic and stable isotope analyses in conjunction with associated clastic cave sediments provide useful insights into the climatic boundary conditions during speleothem formation and into the paleoenvironmental processes which operated in the 2000 m high catchment above the cave our data show that millennial scale temperature fluctuations had a first order control on the periglacial activity and vegetation in the catchment which strongly influenced the formation and infiltration of detritus into the karst aquifer the brown laminated and brown dendritic fabrics that compose much of the detrital rich flowstone succession reflect these environmental processes the temperature dependence of periglacial and permafrost processes allows to constrain the amount of cooling relative to the present day mean annual air temperature that is required to initiate detrital rich calcite formation in entrische kirche cave i e 2 5 c minimum to 6 c maximum respectively white inclusion poor calcite that is intercalated with the detrital rich calcite indicates warm interstadial conditions and geomorphological stability in the catchment area one such phase has been u th dated to 88 3 6 9 ka i e greenland interstadial 21 or 22

lutschine fan delta response to climate variability and land use in the bernese alps during the last 2400 years abstract despite important progress in holocene palaeoclimate and palaeoenvironmental studies in the alps during recent years the knowledge of alpine river dynamics and their chronology is still limited to address the influence of external factors such as climatic variability and land use on aggradation and floods we focused our research on the late holocene sedimentary and geomorphologic history of the lutschine fan delta morphological mapping sedimentology geochemistry palynology historical maps building inventories and 14c dating techniques provided valuable data for the reconstruction of palaeofloods wetland environments and anthropogenic impact the sedimentological findings showed a general agreement between geochemical and pollen changes and 14 c anomalies from 2400 to 850 yr cal bp furthermore the coarse grained layers deposited during palaeofloods about 400 yr cal bc and 100 700 1100 1550 and 1830 ad correlate with positive radiocarbon anomalies suggesting that aggradation in the lutschine fan delta during the focused period was triggered by solar forcing according to our pollen data and the traced correlations the lutschine river floods occurred during cold and wet periods the return interval of recorded flooding events during the last 2400 years varies between 300 and 600 years with regard to the last millennium anthropogenic impacts such as woodland clearance for grazing and agriculture and river diversion have changed the sedimentary and geomorphic pattern on the lutschine fan delta reducing wetland environments

natural attrition and growth frequency variations of stalagmites in southwest sulawesi over the past 530 000 years previous studies have analysed the age distributions of stalagmites harvested from multiple caves and inferred important palaeoclimate changes that explain stalagmite growth phases however stalagmites may grow over tens of thousands of years thus they are irreplaceable the value of speleothems to science must be weighed against their potential and current aesthetic and cultural value in this study we show that some palaeoclimate information can be extracted from a cave system without the removal of stalagmites our case study is based on basal u th dates for 77 individual stalagmites from thirteen caves located in and around bantimurung bulusaraung national park southwest sulawesi indonesia the stalagmites grew during discrete intervals within the last 530 000 years and an analysis of their age distribution shows a first order exponential decrease in the number of older stalagmites surviving to the present day further this exponential relationship is observed in stalagmite populations around the world and is therefore likely to be a general cave phenomenon superimposed on the first order exponential age distribution in southwest sulawesi are positive anomalies in stalagmite growth frequency at 425 400 385 370 345 335 330 315 160 155 75 70 and 10 5 ka which are typically coincident with wet periods on borneo to explain this distribution we present a simple model of stalagmite growth and attrition a first order trend is controlled by processes intrinsic to karst systems that govern the natural attrition of stalagmites these processes are nearly constant over time and result in the observed exponential relationship of stalagmite basal ages second order variation is controlled by changes in the rate of stalagmite generation caused by fluctuating climates which is a well known concept in the speleothem literature removal of the exponential baseline allows for better assessment of relative peak heights and basic palaeoclimate information to be inferred importantly the first and second order growth frequency variations can be characterised using basal stalagmite ages only without the removal of stalagmites thereby helping reduce the impact of scientific sampling on the cave environment

stalagmite stable isotope record of recent tropical cyclone events we present a 23 yr stalagmite record 1977 2000 of oxygen isotope variation associated with 11 tropical cyclones tcs from actun tunichil muknal cave in central belize high resolution microsampling yielded a record of monthly to weekly temporal resolution that contains abrupt decreases negative excursions in calcite 18 o values that correspond with recent tc rain events nearby a logistic discriminant model reliably identifi ed tc proxy signals using the measurable parameters 18 o and 13 c values and single point changes in 18 o value the logistic model cor rectly identifi ed 80 of excursions as tc events and incorrectly classifi ed only 1 of nearly 1200 nonstorm sampling points in addition to enabling high resolution tc frequency reconstruction this geologic proxy also provides information about the intensity of individual tcs a multiple regression predicted tc intensity r 2 0 465 p 0 034 using sampling frequency and excursion amplitude consistent with previous low resolution studies we found that the decadal average 18 o value was lower during the 1990s when several tcs produced rainfall in the area but higher during the 1980s when only one tc struck longer accurately dated high resolution speleo them stable isotope records may be a useful new tool for paleotempestology to clarify associa tions between highly variable tc activity and the dynamic range of quaternary climate

vessel anomalies in quercus macrocarpa tree rings associated with recent floods along the red river of the north united states 1 estimates of future flood risks are based on the observations of past floods but instrumental records of basin hydrology are often too short to assess potential changes in the frequency or magnitude of extreme floods over time in this study we show that bur oak quercus macrocarpa michx growing along the red river of the north in north dakota and minnesota preserve evidence of past floods within their annual growth rings rings formed during major floods often displayed i marked reductions in the size of their earlywood vessels or ii a more diffuse distribution of vessels throughout the increment because of the correspondence between major floods and widespread anatomical anomalies within riparian oaks we suggest that these features can be described as flood rings the frequency of flood ring formation varied substantially along the river which implies that this evidence can only provide an accurate estimate of flood history when it is obtained from many trees sampled across a dense network of sites the rate of flood ring formation is primarily influenced by flood magnitude but is also controlled by the timing and duration of inundation relative to the period of cambial growth although flood affected oaks are imperfect recorders of past floods this approach offers significant potential as a means to estimate the preinstrumental flood history of the red river within the united states

two millennia of tropical cyclone induced mud layers in a northern yucatan stalagmite multiple overlapping climatic hazards during the maya terminal classic megadroughts an annually laminated stalagmite from the northern yucatan peninsula contains mud layers from 256 cave flooding events over 2240 years this new conservative proxy for paleotempestology recorded cave flooding events with a recurrence interval of 8 3 years during the twentieth century with the greatest frequency during the twentieth century and the least frequent during the seventeenth century tropical cyclone tc events are unlikely to flood the cave during drought when the water table is depressed applying tc masking to the chaac paleorainfall reconstruction suggests that the severity of the maya megadroughts was underestimated without a high resolution radiometric geochronology of individual local tc events speleothem isotope records cannot resolve whether the terminal classic period in the northern maya lowlands was punctuated by several brief drought breaks with normal tcs or whether the region was very dry and peppered by unusually severe and frequent hurricane seasons

annually laminated sequences in the internal structure of some belgian stalagmites importance for paleoclimatology abstract fifteen stalagmites from four caves and one sealed tunnel in southern belgium are composed of alternations of annually deposited white porous and dark compact laminae this is demonstrated by comparing the number of laminae with the local history of the site for modern stalagmites and with radioisotopic ages for late glacial and holocene stalagmites annual cyclicity in the internal structure of these speleothems is explained by the highly seasonal variations of the water excess which influences underground water flow comparison between climatic data and modern stalagmites of a closed tunnel shows that growth laminae can record climatic variations 1 there is a good correlation r 0 84 between lamina thickness in a stalagmite and water excess 2 during years with a high water excess dark compact laminae are more developed which makes the speleothem darker vertical successions of several laminae represent microsequences that may have recorded climatic variations with a time resolution of 1 2 year in a late glacial stalagmite successive laminae microsequences form very regular cycles of 11 years separated by a thick darkcompact lamina it is supposed that as for modern stalagmites the thick dark compact lamina corresponds to a period of high water excess hence this 11 year cycle may reflect a climatic cycle

maximum sea levels for the last glacial period from u series ages of submerged speleothems pleistocene sea levels reflect changes in the surface distribution of land sea and ice which in turn significantly influence the earth s climate1 the most complete record of sea levels for the last glacial cycle has come from raised coral reef terraces of the huon peninsula papua new guinea2 4 but interpretation of this record is hampered by relatively large age uncertainties and the possibility of variation in the rate of tectonic uplift subaerial speleothems stalagmites stalactites and flowstones from submerged caves in tetonically stable areas provide an alternative source of data5 8 as their growth stops when rising sea levels flood the caves previous studies of speleothems have been limited by dating precision5 6 and sample availability5 7 here we present high precision thermal ionization mass spectrometric 230th ages9 11 for a comprehensive suite of speleothem samples from the bahamas our results provide a record of maximum elevation of sea levels for the period from 80 to 10 kyr before the present for much of which sea levels are poorly known we also find that regional palaeoclimatic change can be an important factor in the termination of speleothem growth

annual to sub annual resolution of multiple trace element trends in speleothems this study aims to establish evidence for the widespread existence of preserved high resolution trace element variations in speleothems that may have climatic significance ion microprobe analysis of speleothems reveals that annual to sub annual variations in element chemistry exist at five shallow western european cave sites crag cave county kerry and ballynamintra county waterford ireland uamh an tartair sutherland scotland grotte pere noel belgium grotta di ernesto ne italy with widely varying climatic geomorphic and geological settings the variations are not restricted to species mg sr and ba known to substitute directly for ca in the calcite lattice but include h f na and p phosphorus as phosphate displays the greatest variability and may have the most significance as a proxy for the seasonal temperature cycle because of its role as a nutrient element the technique allows estimation of growth rate of speleothems at any interval of interest which is one of several possible uses in palaeoclimatology

climatic and environmental controls on speleothem oxygen isotope values variations in speleothem oxygen isotope values d 18 o result from a complicated interplay of environmental controls and processes in the ocean atmosphere soil zone epikarst and cave system as such the controls on speleothem d 18 o values are extremely complex an understanding of the processes that control equilibrium and kinetic fractionation of oxygen isotopes in water and carbonate species is essential for the proper interpretation of speleothem d 18 o as paleoclimate and paleoenvironmental proxies and is best complemented by study of site specific cave processes such as infiltration flow routing drip seasonality and saturation state and cave microclimate among others this review is a process based summary of the multiple controls on d 18 o in the atmosphere soil epikarst and speleothem calcite illustrated with case studies primary controls of d 18 o in the atmosphere include temperature and relative humidity through their role in the multiple isotope effects variability and modifications of water d 18 o values in the soil and epikarst zones are dominated by evaporation mixing and infiltration of source waters the isotopically effective recharge into a cave system consists of those waters that participate in precipitation of caco3 resulting in calcite deposition rates which may be biased to time periods with optimal dripwater saturation state recent modeling experimental and observational data yield insight into the significance of kinetic fractionation between dissolved carbonate phases and solid caco3 and have implications for the hendy test to assist interpretation of speleothem d 18 o time series quantitative and semi quantitative d 18 o climate calibrations are discussed with an emphasis on some of the difficulties inherent in using modern spatial and temporal isotope gradients to interpret speleothems as paleoclimate proxy records finally several case studies of globally significant speleothem paleoclimate records are discussed that show the utility of d 18 o to reconstruct past climate

paleoflood events recorded by speleothems in caves speleothems are usually composed of thin layers of calcite or aragonite however cemented detrital materials interlayered between laminae of speleothemic carbonate have been also observed in many caves flowstones comprising discontinuous carbonate layers form due to flowing water films while flood events introduce fluviokarstic sediments in caves that on occasion are recorded as clayey layers inside flowstones and stalagmites this record provides a potential means of understanding the frequency of palaeofloods using cave records in this work we investigate the origin of this type of detrital deposit in el soplao cave northern spain the age of the lowest aragonite layer of a flowstone reveals that the earliest flood period occurred before 500 ka though most of the flowstone formed between 422 69 43 ka and 400 66 42 ka this suggests that the cave was periodically affected by palaeoflood events that introduced detrital sediments from the surface as a result of occasional extreme rainfall events especially at around 400 ka the mineralogical data enable an evolutionary model for this flowstone to be generated based on the alternation of flood events with laminar flows and carbonate layers precipitation that can be extrapolated to other caves in which detrital sediments inside speleothems have been found copyright 2014 john wiley sons ltd