reconstructing high resolution climate using ct scanning of unsectioned stalagmites a case study identifying the mid holocene onset of the mediterranean climate in southern iberia the forcing mechanisms responsible for the mid holocene onset of the mediterranean type climate in south western europe are currently unclear but understanding these is critical for accurate climate projections under future greenhouse gas warming additionally regional studies that present conflicting patterns for the onset and advancement of mediterranean climatic conditions complicate definitively ascribing causality here we use a new high resolution stalagmite density record obtained non destructively using computed tomography ct scanning to reconstruct southern iberian climate between 9 3 and 2 9 ka bp we suggest that stalagmite density can be used as a water excess proxy with lower densities associated with more variable drip rates possibly reflecting increased seasonality consistent with expectations from previous studies of speleothem textures and crystal fabrics our results reveal an early holocene humid interval and mid holocene year round aridity that preceded the onset of mediterranean climate at 5 3 ka bp in southern iberia using this new dataset combined with previously published results we link the gradual advancement of the mediterranean climate to the southward migration of the north atlantic subtropical high induced by an orbitally driven decrease in northern hemisphere insolation future anthropogenic warming could result in a reversal of this trend a northward migration of the north atlantic subtropical high and a return to year round aridity in south western europe

baroclinic eady wave and fronts part i viscous semigeostrophy and the impact of boundary condition abstract a two dimensional viscous semigeostrophic model is developed to study the evolution of the baroclinic eady wave and fronts with two types free slip and nonslip of boundary conditions with the free slip boundary condition the solution is very similar to the inviscid one but the frontal collapse is prevented by the diffusive effect when the fronts become sharp in the mature stage strong horizontal diffusions of momentum and potential temperature cause strong inward fluxes of geostrophic potential vorticity gpv at the surface fronts so high gpv anomalies are generated at the surface fronts and advected into the interior forming two backward tilted plumes along the upper and lower fronts the wave and front development can be interpreted by the interaction between the lower and upper level gpv anomalies in terms of gpv thinking similarly to that in the inviscid case when the boundary condition is nonslip the initial growth and subsequent nonlinear evolution of the solution are significan

provenance of early bronze age metal artefacts in western switzerland using elemental and lead isotopic compositions and their possible relation with copper minerals of the nearby valais abstract ten early bronze age bza1 2200 2000 bc copper artefacts from the central valais region from switzerland were studied for their elemental composition and lead isotope ratios in order to answer the archaeological question of a local copper supply a database for copper minerals across the valais switzerland has been established this database contains 69 data on lead isotope ratios as well as additional information on the minerals and geochemical associations for copper minerals from 38 locations in the valais comparisons of the artefacts were also made with data pertaining to minerals from various deposits from europe and anatolia taken from the literature the provenance of the materials is very diverse some of the data are compatible with the data from the copper mineral deposits of the valais region moreover three copper lunulae were identified as possibly tuscan which suggests contacts between italy and the valais region this pattern also establishes a multiplicity of provenances for the metal and cultural influences in the alpine environment of the rhone valley of switzerland at the beginning of the early bronze age

the impact of mining activities on the environment reflected by pollen charcoal and geochemical analyses abstract this article presents results of a multi proxy study of a fen deposit in the former mining district of falkenstein near schwaz in the tyrol austria the aim of the study in the framework of the special research program himat the history of mining activities in the tyrol and adjacent areas impact on environment human societies was to disclose the ecological impact of mining in pollen and heavy metal diagrams and to create a model combining the changes in palaeoecological proxies with historical evidences for mining the application of this palaeoecological historical model to prehistoric times allowed us to reconstruct the impact of mining and metallurgic activities in the surroundings of the fen during the last millennia the results of stratigraphy radiocarbon dating loi pollen and micro charcoal analyses as well as geochemical analyses of scandium lead and lead isotopes validated by historical and archaeological data are hereby presented

hydrological change in southern europe responding to increasing north atlantic overturning during greenland stadial 1 greenland stadial 1 gs 1 was the last of a long series of severe cooling episodes in the northern hemisphere during the last glacial period numerous north atlantic and european records reveal the intense environmental impact of that stadial whose origin is attributed to an intense weakening of the atlantic meridional overturning circulation in response to freshening of the north atlantic recent high resolution studies of european lakes revealed a mid gs 1 transition in the climatic regimes the geographical extension of such atmospheric changes and their potential coupling with ocean dynamics still remains unclear here we use a subdecadally resolved stalagmite record from the northern iberian peninsula to further investigate the timing and forcing of this transition a solid interpretation of the environmental changes detected in this new accurately dated stalagmite record is based on a parallel cave monitoring exercise this record reveals a gradual transition from dry to wet conditions starting at 12 500 y before 2000 a d in parallel to a progressive warming of the subtropical atlantic ocean the observed atmospheric changes are proposed to be led by a progressive resumption of the north atlantic convection and highlight the complex regional signature of gs 1 very distinctive from previous stadial events

reconstruction of holocene high altitude vegetation cover in the french southern alps evidence from soil charcoal the study presented here from the southern french alps demonstrates the reliability of soil charcoal analysis for the study of holocene past treeline positions the occurrence of charcoal in mineral soils along transects from 1950 m up to 2920 m demonstrates the role of fire in the establishment of the present vegetation patterns the abrupt decrease of charcoal concentration at about 240 0 2 600 m which varies across the study sites corresponds to the modern transition between subalpine forest and alpine tundra charcoal particles formedinsitu providehighspatial resolutiondataforthereconstructionofpastforestandtreelinechanges soil charcoal analysis indicated that 1 treeline was 300 m higher around 6800 cal bp than today and 2 the uppermost forest belt up to 2810 m was colonized by larch larix decidua mill and arolla pine pinus cem bra l thispineispresenttodaybutpatchilydistributed itisabsentfromthethreeareasstudied radiocarbon dates ranging from c 6800 cal bp to the modern period along with historical and archaeological data sug gest that the present pattern of the uppermost forest belt and the patchy distribution of arolla pine in the stud ied area are the results of anthropogenic fire mainly agropastoral activities the question of global warming consequences on treelines in this part of the french alps is discussed

anthracological analysis of fuel wood used for firesetting in medieval metallic mines of the faravel district southern french alps this anthracological study of fuel wood used in the faravel mines is part of a doctorate research pro gramme conducted on the interrelationship between mines and forests of the southern alps during the middle ages the study area is situated in the upper durance valley a major mining region from the 11th to the end of the 13th century man sought and extracted silver bearing ore from the valley bottoms to the summit of the mountains he employed firesetting to attack the hard gneiss bedrock the study of residual charcoal has been used to measure the impact of the mining economy on the development of mountain forests the example of the small district of faravel situated in an upper mountainous region 1900e2150 m altitude illustrates a supply anchored at subalpine level with a gradual extension of the source area towards the timberline the anthracological spectra document extinction of pinus cembra l at subalpine level and the lowering of the upper limit of the dense forest dominated by larix decidua mill these changes are the result of agropastoral and mining pressure as testified by both surviving man uscripts and archaeology

holocene vegetation responses to fire events in the inner french alps queyras massif data from charcoal and geomorphological analysis of travertine sequences travertines are calcareous deposits that result from water stream saturation in bicarbonate they are extremely sensitive to environmental variations homeostatic conditions such as a good development of vegetation and regular river flow induce the formation of homogenous travertine facies enclosing plant imprints significant climatic changes and or human perturbations may disturb the carbonate deposit favouring an increase in detrital material often rich in charcoal remains travertine systems located in the queyras massif aigue agnelle and peynin valley provided abundant charcoal material its analysis allowed us to identify five vegetation phases between c 8400 and 1709 cal yr bp and to ascertain holocene vegetation responses to fire perturbation an ecological dynamic based on forest fire events is proposed during periods of reduced fire frequencies long term fire cycle pinus cembra dominated the queyras massif vegetation the predominance of travertine facies during these phases corroborates this interpretation periods of increased fire frequency triggered the development of larix decidua picea abies short term fire cycle this vegetation change was concomitant with the deposition of thick detrital layers resulting from slope erosion as a consequence of recurrent fire perturbations the permanent settlement in this region of human communities since c 4400 cal yr bp favoured the development of larix decidua picea abies finally our results suggest that the collapse of agropastoral activities since ad 1950 might progressively lead to the regeneration of pinus cembra

interdisciplinary characterisation and environmental imprints of mining and forestry in the upper durance valley france during the holocene the upper durance valley contains the largest silverelead mines of the french southern alps we investigated the characterisation and impact of these mining activities and associated forestry in the argentiere l argentiere la bessee and faravel freissinieres districts using a multidisciplinary approach that includes archaeological palynological geochemical anthracological and dendrochrono logical studies applied to mining remnants and a peat bog fangeas in the faravel district more specifically we studied the occurrence of lead contamination episodes the chronology of mining activities and their link to the evolution in woodland cover our chronology is based on mining archaeology radiocarbon dating of about thirty charcoal samples and the dendrochronological analysis of more than 170 specimens of exhumed waterlogged wood the anthracological analysis was established with more than 10 000 charcoals from firesetting the main geochemical approach was based on the analysis of lead and its stable isotopes in sediment fractions from a peat core the combination of palynological records and lead isotope imprints were used to characterise i a roman contamination episode unknown to archaeology ii the development of medieval mining activities and iii the reactivation of mining during the modern period and the industrial revolution medieval mining coincides with an extension of the high mountain agropastoral areas the in situ continuous human activities in the same industrial territory led to rational communal management of subalpine forests but also to their parcelling that reached its peak in the high middle ages mining during the modern period coincides with significant stress on woodland areas that also appears to be related to lumber and fuel timber production for shipyards french royal navy as well as the functioning of several military fortresses the mining reactivation during the 19th c matched public measures of forest protection that took shape in the afforestation programme of the uplands

baroclinic instability in an environment of small stability to slantwise moist convection part i two dimensional models abstract in the semigeostrophic system the growth rate of baroclinic waves varies with the inverse square root of the potential vorticity which acts as the effective static stability recent observations in the ascent regions of middle latitude cyclones show that the effective potential vorticity for saturated air is very near zero in this paper we examine the structure and rate of growth of baroclinic cyclones when the effective potential vorticity is small for upward saturated displacements but large in regions of descent analytic solutions for two dimensional disturbances in a two layer semigeostrophic model and numerical simulations using a multilevel semigeostrophic model show that when the effective potential vorticity is small in regions of upward motion growth rates are modestly increased and the region of ascent intensifies and collapses onto a thin ascending sheet in the limit of zero moist potential vorticity the fastest growing wave has a finite growth rate which is about 2 5 times the

baroclinic waves and frontogenesis with an embedded zone of small moist symmetric stability three dimensional semigeostrophic moist baroclinic waves and frontogenesis are studied both analytically and numerically it is found that a slantwise zone of small either unconditional or quasi conditional moist symmetric stability embedded in a dry and baroclinic basic state traps the energy of baroclinic waves forming a strong meridional structure with maximum wave amplitude in the moist zone and exponential decay of the wave amplitude away from the moist zone the unstable waves absorb energy from both the moist and dry baroclinic basic state but the strongest energy conversion is in the moist zone so growth rates decrease with the width of the moist zone as the moist zone becomes infinitely narrow wide the model degenerates into a dry moist eady model the smaller the moist symmetric stability the larger the growth rate and the wavenumber of the most unstable wave the valid range of the model parameters depends on the semigeostrophic approximation which sets a limit to the smallness of the moist symmetric stability in semigeostrophic space the moist zone changes shape due to geostrophic deformation as the wave develops in real space the surface pressure low high shifts northward southward due to geostrophic deformation tightens expands due to ageostrophic convergence divergence and goes on to form a coupled warm cold frontal system a numerical model of the semi lagrangian finite element method is developed the method is shown to be accurate in computing wave growths and efficient in resolving frontal structures although the semigeostrophic approximation is found to become poor or even invalid locally in the narrow meso scale cold frontal region

silver and lead in high altitude lake sediments proxies for climate changes and human activities abstract high altitude lake sediments are often used as archives for environmental changes and their chemical and isotopic compositions provide significant constraints on natural and anthropogenic long term changes that have occurred in their catchment area here trace element concentrations and pb isotopes are presented for two sedimentary cores from lake blanc huez in the french alps to trace the impact of climate changes and human activities over the holocene lead and ag contents are very high and clearly dominated by input from a pb ag vein located a few meters from the lakeshore a vein that also buffers the pb isotopes mining of this vein in medieval times is recorded in the corresponding lake sediments with high ag content coupled with high pb u ratio these chemical characteristics can be used to constrain the major holocene climate changes significant advances of glaciers next to the lake produced sediments with ag and pb concentration peaks and high pb u ratios due to accelerated erosion of the pb ag vein similar to the effects of the medieval mining in contrast reduced glacier activity led to the formation of organic rich sediments with high u and as contents and low pb u ratios more generally the observed combination of chemical changes could be used elsewhere to decipher environmental changes over long periods of time

impacts of cave air ventilation and in cave prior calcite precipitation on golgotha cave dripwater chemistry southwest australia abstract speleothem trace element chemistry is an important component of multi proxy records of environmental change but a thorough understanding of hydrochemical processes is essential for its interpretation we present a dripwater chemistry dataset pco2 alkalinity ca sicc mg and sr from an eight year monitoring study from golgotha cave building on a previous study of hydrology and dripwater oxygen isotopes treble et al 2013 golgotha cave is developed in quaternary aeolianite and located in a forested catchment in the mediterranean type climate of southwest western australia all dripwaters from each of the five monitored sites become supersaturated with respect to calcite during most of the year when cave ventilation lowers pco2 in cave air in this winter ventilation mode prior calcite precipitation pcp signals of increased mg ca and sr ca in dripwater are attributed to stalactite deposition a fast dripping site displays less evolved carbonate chemistry implying minimal stalactite growth phenomena which are attributed to minimal degassing because of the short drip interval 30 s we employ hydrochemical mass balance modelling techniques to quantitatively investigate the impact of pcp and co2 degassing on our dripwater initially we reverse modelled dripwater solutions to demonstrate that pcp is dominating the dripwater chemistry at our low flow site and predict that pcp becomes enhanced in underlying stalagmites secondly we forward modelled the ranges of solution mg ca variation that potentially can be caused by degassing and calcite precipitation to serve as a guide to interpreting the resulting stalagmite chemistry we predict that stalagmite trace element data from our high flow sites will reflect trends in original dripwater solutes preserving information on biogeochemical fluxes within our system by contrast stalagmites from our low flow sites will be dominated by pcp effects driven by cave ventilation our poorly karstified system allows us to highlight and quantify these in cave pcp processes which are otherwise masked at sites where karstification is more developed and hydrogeology is more complex our modelling also shows enhanced co2 source production in the unsaturated zone that is attributed to deeply rooted vegetation and increasing bioproductivity which we link to forest recovery after fires impacted our site during 2006 ce

a historical ecology of the ecrins southern french alps archaeology and palaeoecology of the mesolithic to the medieval period this paper elucidates the nature of human environment interactions in a mountainous landscape the southern zone of the ecrins french alps from the mesolithic through to the post medieval period we present an integrated programme of palynology pedo and archaeo anthracology and archaeology these data permit the development of a historical ecology that allows us to differentiate between climatic and anthropogenic influences on vegetation and the development of anthropogenic landscapes in an alpine region this study is of profound relevance for the broader understanding of human environment interactions in ecologically sensitive environments both within the alpine arc but also beyond this region we identify and explain evidence for possible human landscape management practices in a high altitude landscape palynology defines the broad floral context and evolution of the environment through the holocene palynology also permits an assessment of human activities and practices arable agriculture pastoralism and haymaking the combination of these data with anthracological and archaeological evidence permits a nuanced assessment of human interaction with the landscape we consider phases of anthropological ecological succession across the range of altitudes from valley bottom to the alpine zones in the ecrins national park four important stages of landscape use and change have been inferred from our evidence the mesolithic the chalcolithic bronze age iron age and roman and post medieval during the mesolithic c 8000 4500 bc a major event is the expansion of fir in the montane stage at higher altitudes people exploit the ecotone defined by the forest edge or tree line an ideal zone for hunting the neolithic sees low altitude clearances but a continuation of hunting and low levels of human impact on high altitude vegetation the chalcolithic bronze age 2400 1000 bc sees complex interplay of climatic changes and the appearance of direct human intervention in the high altitude landscape as part of a new transhumant system although the roman period is characterised by phases of climatic amelioration after the deterioration of the iron age the increase in human activity that is usually seen in low lying areas is not reflected in the sub alpine and alpine altitudes the medieval period including the little ice age witnesses a steady increase in human use of these landscapes with forest manipulation and clearance becoming the defining characteristics of these areas despite the supposed inclement nature of the little ice age human activity achieves its zenith and the combination people and climate produces the most open and managed landscape of the holocene

pre historic changes in natural and anthropogenic heavy metals deposition inferred from two contrasting swiss alpine lakes abstract continuous high resolution sedimentary record of heavy metals chromium cr copper cu lead pb zinc zn manganese mn and mercury hg from lakes lucerne and meidsee switzerland provides pollutant deposition history from two contrasting alpine environments over the last millennia the distribution of conservative elements thorium th scandium sc and titanium ti shows that in absence of human disturbances the trace element input is primarily controlled by weathering processes i e runoff and erosion nonetheless the enrichment factor ef of pb and hg that are measured by independent methods and the pb isotopic composition of sediments from the remote lake meidsee which are proportionally more enriched in anthropogenic heavy metals likely detect early mining activities during the bronze age meanwhile the deposition of trace elements remains close to the range of natural variations until the strong impact of roman activities on atmospheric metal emissions both sites display simultaneous increases in anthropogenic trace metal deposition during the greek and roman empires ca 300 bc to ad 400 the late middle ages ca ad 1400 and the early modern europe after ca ad 1600 however the greatest increases in anthropogenic metal pollution are evidenced after the industrial revolution of ca ad 1850 at low and high altitudes during the twentieth century industrial releases multiplied by ca 10 times heavy metal fluxes to hydrological systems located on both sides of the alps during the last decades the recent growing contribution of low radiogenic pb further highlights the contribution of industrial sources with respect to wood and coal burning emissions

i stal a model for interpretation of mg ca sr ca and ba ca variations in speleothems and its forward and inverse application on seasonal to millennial scales 1 trace element ratios mg ca sr ca and ba ca are readily measured in speleothems and may be closely related to hydrological balance enhancing paleoclimate information inferred from stable isotope measurements we develop a model which simulates the variation in dripwater chemistry resulting from variable degree of water rock interaction and prior calcite precipitation pcp with the latter process depending both on drip interval and drip oversaturation with respect to caco3 partition coefficients between speleothem and dripwater are dependent on temperature for mg and on speleothem growth rate for sr and ba as observed in laboratory experiments the drip oversaturation state regulated both by cave pco2 and the dilution and soil karst dissolution processes strongly affects stalagmite trace element concentrations by modulating the extent of pcp and speleothem growth rates application of an inverse model confirms that seasonal co2 cycles can explain the uncorrelated seasonal cycles in mg ca and sr ca observed in our speleothem records from nw spain for which high co2 coincides with dry season in absence of seasonal variations in drip interval cycles in cave pco2 can produce seasonal covariation in sr ca mg ca and ba ca in long time series 104 yr where seasonal sampling resolution is not obtained in stalagmites a change from dominance of summer to winter rainfall can shift the season of strongest stalagmite deposition to one of lower mean co2 and hence greater pcp and higher mg ca sr ca and ba ca ratios caves best suited to record a dominantly water balance signal such as mean drip intervals are those with minimal seasonal variation in cave pco2

late holocene history of woodland dynamics and wood use in an ancient mining area of the pyrenees ariege france this paper focuses on past woodland changes and land uses in an ancient mining area of the eastern pyrenees ari ege france the area discussed is located at the western entrance of the vicdessos a valley with significant steel production and it is crossed by the road used from the 14th c to the end of the 18th c for the iron charcoal exchange with the forest province of couserans the introduction of this singular exchange and the silver ore mining history of this border area raise the question of their impact on forest cover changes and changes in human practices and their link with anthropisation processes to deal with this issue we put in place an interdisciplinary approach involving archaeology charcoal analysis ecological history and geochemistry the archaeological investigations and fourteen radiocarbon ages allowed characterising and dating of mining and charcoal making remains they situate the emergence of metal ore mining during the second iron age and charcoal making activity between the 15th and 17th c the geochemical analysis of 9 galena samples showed some different isotopic signatures between ores extracted in ancient times and those mined during the modern period the charcoal analysis of i 2442 charcoals from 31 charcoal kilns ii 500 from one pedoarchaeological pit excavated in a waste heap related to firesetting and iii 250 from two pedoanthracological sampling points carried out in the charcoal burning forest permits a detailed reconstruction of the woodland cover changes from the second iron age to the 19th c furthermore the combination of data from different disciplines allows for a long term reconstruction of human practices history and woodland management for different uses in particular the results show the transformation of the fir beech forest still dominated by fir around the turn of the roman era into pure beech wood managed on northern slopes for human daily needs occasionally mining lumber and mainly charcoal production until the 19th c the elimination of fir dates back to the 17th c this assumes the end of lumber activities in that period pedoanthracological and palynological data suggest that southern slopes progressively deforested since the bronze age were entirely devoted to permanent agropastoral activities probably at least since the end of the medieval period

seasonal variations of physical and chemical erosion a three year survey of the rhone river france abstract numerous studies of weathering fluxes have been carried out on major world rivers during the last decade to estimate co 2 consumption rates landscape evolution and global erosion rates for obvious logistical reasons most of these studies were based on large scale investigations carried out on short timescales by comparison much less effort has been devoted to long term monitoring as a means to verify the temporal variability of the average characteristics their trends and the representativeness of short term investigations here we report the results of a three year survey november 2000 to december 2003 of the major and trace element composition of dissolved and suspended matter in the lower rhone river france the largest river of the mediterranean area subsurface water samples were collected in arles about 48 km upstream of the estuary twice a month routinely and at higher frequency during flood events during each flood event the suspended particulate matter spm show the usual trend of clockwise hysteresis with higher spm concentrations on the rising limb of the flood than at the same discharge on the falling limb we show that the annual average spm flux of the rhone river to the mediterranean sea 7 3 0 6 10 6 tons yr 1 was largely controlled by the flood events 83 of the solid discharge occurred in less than 12 of the time and that the precision on the total output flux depends strongly on the precise monitoring of spm variations during the floods the chemical composition of water and spm are characterized by the predominance of ca 2 due to the abundance of carbonate rocks in the rhone watershed chemical budgets have been calculated to derive the contributions of atmospheric deposition carbonate silicate and evaporite weathering and anthropogenic inputs the chemical weathering rate of carbonates is estimated to be 89 5 t km 2 yr 1 compared to 14 4 3 t km 2 yr 1 from silicates by contrast the physical erosion rate of silicates is about 51 t km 2 yr 1 against 19 t km 2 yr 1 for carbonates the steady state model of gaillardet et al 1995 has been applied to the chemical composition of dissolved and solid products the results show that the rhone river currently exports much less material than produced at steady state by weathering in its watershed the sediment flux inferred from the steady state calculation 21 56 10 6 t yr 1 is on the same order as that estimated in literature for the 19th and the beginning of the 20th centuries this imbalance may suggest that the rhone is under a transient erosion regime following climate change i e significant decrease of the flooding frequency since the beginning of the 19th century on the other hand the imbalance may also be due to the trapping of alluvion by the numerous dams on the river and its tributaries our data corroborate with previous studies that suggest a strong coupling between chemical and physical erosion fluxes during the hydrological seasonal cycle of the rhone river the correlation between physical and chemical transport rates is however clearly different from that reported for global annual averages in large world rivers

changes of lead and barium with time in california off shore basin sediments during ancient times the natural deposition fluxes of lead which can be leached with dilute acid from sediments in santa barbara santa monica and san pedro basins offshore from the los angeles urban complex were about 0 7 0 1 and 0 2 g pb cm 2 yr respectively since there was little difference in biological productivity in surface waters of these basins it is proposed that clay is a major transport vehicle for sequestered soluble lead which then explains why the lead deposition flux within the santa barbara basin was so much larger compared to the other basins the fluxes of silicate mud in the basins in ancient times were about 92 19 and 30 mg cm 2 yr in santa barbara santa monica and san pedro basins respectively today deposition fluxes of acid soluble lead within these three basins are 3 to 9 fold greater being about 2 1 1 1 and 1 8 g pb cm 2 yr respectively partly in the form of directly deposited large sewage particles which account for none 2 3 and 3 4 of the total industrial lead deposition fluxes in the respective basins concentrations of leachable lead in varve dated sediment layers increase with time and isotopic compositions of these leads change in accordance with corresponding known changes of isotopic compositions of industrial lead in the los angeles atmosphere lead remaining in acid leached sediment residues originates from igneous and clay minerals exhibiting no change in concentration or isotopic composition since pre industrial times deposition fluxes of total barium in sediments among the three basins were proportional to mass deposition fluxes before 1950 in the same manner as for lead afterwards there are barium concentration maxima with time in both santa monica and san pedro basin sediments which are attributable to industrial sewage rather than to episodic erosion from barium rich sedimentary evaporite strata exposed locally along the shore an increase of barium concentrations in present day santa barbara basin sediments may reflect dispersal of barium rich drilling mud from local drilling operations

frontogenesis in the presence of small stability to slantwise convection abstract it is often observed that despite the existence of near neutrality to slantwise convection rainbands and snowbands can persist for long periods with narrow intense updrafts producing large quantities of precipitation in many cases this is probably due to the presence of active frontogenesis which as shown here maintains such structures in order to investigate this process we use two dimensional semigeostrophic theory to solve the deformation forced frontogenesis problem for a circumstance in which the stability to moist slantwise convection is small but positive in this case numerical simulation is necessary to determine the evolution of the front several previous studies have described the role of diabatic forcing in modifying the cross frontal circulation by use of the sawyer eliassen equation in particular analytic solutions of that equation for the case of small moist symmetric stability show that a narrow updraft should occur ahead of the maximum geostrophic frontogenesis numeri

charcoal analysis and dendrology data from archaeological sites in north western france during the last 15 years charcoal analysis of archaeological sites in north western france has been carried out in conjunction with systematic and detailed dendrological examination by considering these extrinsic criteria in association with the analytical results palaeo ethnographic and palaeo environmental information can be obtained the charcoals are classically identified under the microscope on the basis of their cellular structure this examination is associated with an observation of the ligneous structure on transverse sections using a binocular lens when charcoal fragments are large enough the growth ring widths are measured tree ring curvature is also noted finally alteration by fusion or radial cracks the presence of fungal hyphae and insect degradation are also recorded results are thus obtained on the nature of fuel used in domestic fireplaces and kilns the selection of timbers and their catchment areas are also revealed the average width of the growth rings in oak charcoal from domestic hearths coming from about forty sites in north western france shows a significant increase from 6000 to 2000 bp there is a similar increase in the number of heliophilic taxa used from the neolithic to the iron age this implies that the environment became more and more open because of use by society the interpretation of the dendrology results applied to charcoal analyses is obtained through a convergence of criteria thus charcoal analysis can provide more than just an identification of the species used and can yield fundamental information on the interaction of society with the environment

a palaeoenvironmental investigation of sediments from the prehistoric mine of copa hill cwmystwyth mid wales this paper investigates the use of mine sediments to reconstruct the vegetational changes and atmospheric pollution history associated with prehistoric and mediaeval metal mining in the ystwyth valley dyfed mid wales pollen charcoal plant macrofossils fossil insects and chemical analyses are presented from radiocarbon dated sediments contained within a prehistoric mine situated on the upper slope of copa hill close to the village of cwmystwyth the results provide additional support to the hypothesis that prehistoric mining had a negligible impact on woodland and that deforestation took place after bronze age mining ceased although high concentrations of cu pb and zn were determined from sediments of prehistoric and roman age the patterns bear little resemblance to off site atmospheric pollution records and to the archaeological evidence for metal mining interpreting geochemical data from mine contexts is problematic as numerous factors influence the distribution and concentration of metals however an on site and off site approach to investigate human environment interactions caused by metal mining is advocated

speleothem δ13c record suggests enhanced spring summer drought in south eastern spain between 9 7 and 7 8 ka a circum western mediterranean anomaly south eastern spain is one of the driest regions in europe and thus prone to drought terrestrial climate records covering the late glacial and holocene from this area are sparse here we present