methodology of the last climatic cycle reconstruction in france from pollen data abstract a numerical method has been devised to reconstruct the climate of the last climatic cycle from pollen data reliable annual reconstructions have been published recently for the two french long sequences of la grande pile and les echets covering the last 140 millennia this paper gives more details on the method used it proposes new reconstructions based on an extended modern pollen data base these reconstructions are consistent with the previous ones especially detailed information is obtained on the seasonal characteristics of climate computations of gcm on the climate variations from 125 kyr to 115 kyr b p are confirmed for western europe the insolation variations have induced at that time a decrease of seasonality accompanied by an increased cyclonic activity in winter this has been the beginning of the first ice growth after the last interglacial other glacier growth phases are detected at the end of substage 5c and particularly at the end of substage 5a

climate correlations between greenland and antarctica during the past 100 000 years the ice cores recovered from central greenland by the grip1 2 and gisp23 projects record 22 interstadial warm events during the part of the last glaciation spanning 20 105 kyr before present the ice core from vostok east antarctica records nine interstadials during this period4 5 here we explore links between greenland and antarctic climate during the last glaciation using a high resolution chronology derived by correlating oxygen isotope data for trapped o2 in the gisp2 and vostok cores we find that interstadials occurred in east antarctica whenever those in greenland lasted longer than 2 000 years our results suggest that partial deglaciation and changes in ocean circulation are partly responsible for the climate teleconnection between greenland and antarctica ice older than 115 kyr in the gisp2 core shows rapid variations in the 18o of o2 that have no counterpart in the vostok record the age depth relationship and thus the climate record in this part of the gisp2 core appears to be significantly disturbed

abrupt environmental oscillations during the early weichselian recorded at lago grande di monticchio southern italy abstract this study presents multi proxy data from a new core from lago grande di monticchio italy extending back to about 100 000 calendar years bp the time scale of this record is independent from deep sea and ice core chronologies and has been established from a combination of varve counts and high resolution sedimentation rate calculations based on microscopic sediment investigation this paper focuses on environmental variability between 100 000 and 65 000 calendar years bp several abrupt cold periods have been recognised and correlated to other terrestrial as well as to ice core and deep sea records the longest of the monticchio cold phases corresponds to marine isotopic stage 5b and lasted from ca 87 000 to 84 000 calendar years bp two shorter events about 1000 years long occurred during the transition from interstadial to full glacial conditions between 79 000 and 75 000 calendar years bp the increased frequency of cold events during this time interval probably indicates a higher degree of climatic instability in periods of major changes dating discrepancies between monticchio grip and deep sea chronologies range between a few hundred to a few thousand years however these differences in dating are not constant but vary significantly for different sections of the records nevertheless the good match of environmental fluctuations at monticchio with atmospheric variability at the greenland summit as well as variations in the oceanic circulation pattern suggests a close link of the mediterranean to the atlantic climate regime

rapid environmental changes in southern europe during the last glacial period oxygen isotope records from greenland ice cores1 2 indicate numerous rapid climate fluctuations during the last glacial period north atlantic marine sediment cores show comparable variability in sea surface temperature and the deposition of ice rafted debris3 4 5 in contrast very few continental records of this time period provide the temporal resolution and environmental sensitivity necessary to reveal the extent and effects of these environmental fluctuations on the continents here we present high resolution geochemical physical and pollen data from lake sediments in italy and from a mediterranean sediment core linked by a common tephrochronology our lacustrine sequence extends to the past 102 000 years many of its features correlate well with the greenland ice core records demonstrating that the closely coupled ocean atmosphere system of the northern hemisphere during the last glacial4 extended its influence at least as far as the central mediterranean region numerous vegetation changes were rapid frequently occurring in less than 200 years showing that the terrestrial biosphere participated fully in last glacial climate variability earlier than 65 000 years ago our record shows more climate fluctuations than are apparent in the greenland ice cores together the multi proxy data from the continental and marine records reveal differences in the seasonal character of climate during successive interstadials and provide a step towards determining the underlying mechanisms of the centennial millennial scale variability

sedimentological and mineralogical records from drill core skd1 in the jianghan basin central china and their implications for late cretaceous early eocene climate change abstract the jianghan basin central china contains a thick continuous sequence of early cenozoic evaporite bearing deposits that provide a wealth of information about early cenozoic climate change and evaporites accumulation in east asia however the paleoclimatic history of the basin and its effect on the evaporites are largely unknown we obtained a deep drill core skd1 2346 5 m long from the late cretaceous to early eocene evaporite bearing deposits in the jianghan basin detailed analyses of the lithofacies mineralogy and geochemistry of the core indicate that salinization and deepening of the lake occurred corresponding to the yuyang formation to the lower xingouzui formation followed by desalting and shallowing corresponding to the upper xingouzui formation reconstruction of the spatiotemporal evolution of the evaporites in the jiangling depression suggests a transition from semi arid conditions in the late cretaceous to extremely arid conditions in the initial stage of the eocene the climate then became semi humid during the deposition of the upper xingouzui formation indicating a monsoon or monsoon like climate in east asia during the early eocene the southward migration of the depocenter of the jiangling depression coupled with a warm and extremely arid climate resulted in the precipitation of evaporites during the accumulation of the upper shashi formation and the lower xingouzui formation these results indicate great potential for identifying potash resources within the subsag in the southern jiangling depression

anisotropy and depth related heterogeneity of hydraulic conductivity in a bog peat ii modelling the effects on groundwater flow anisotropy and heterogeneity of hydraulic conductivity k are seldom considered in models of mire hydrology we investigated the effect of anisotropy and heterogeneity on groundwater flow in bog peat using a steady state groundwater model in five model simulations four sets of k data were used the first set comprised measured k values from an anisotropic and heterogeneous bog peat these data were aggregated to produce the following simplified data sets an isotropic and heterogeneous distribution of k an isotropic and homogeneous distribution and an anisotropic and homogeneous distribution we demonstrate that where anisotropy and heterogeneity exist groundwater flow in bog peat is complex fine scale variations in k have the potential to influence patterns and rates of groundwater flow however for our data at least it is heterogeneity and not anisotropy that has the greater influence on producing complex patterns of groundwater flow we also demonstrate that patterns and rates of groundwater flow are simplified and reduced when measured k values are aggregated to create a more uniform distribution of k for example when measured k values are aggregated to produce isotropy and homogeneity the rate of modelled seepage is reduced by 28 we also show that when measured k values are used the presence of a drainage ditch can increase seepage through a modelled cross section our work has implications for the accurate interpretation of hydraulic head data obtained from peat soils and also the understanding of the effect of drainage ditches on patterns and rates of groundwater flow

paleosalinity evolution of the paleogene perennial qaidam lake on the tibetan plateau climatic vs tectonic control as the largest cenozoic terrestrial intermountain basin in the tibetan plateau the qaidam basin is an ideal basin to understand the coupling controls of tectonics and climate on plateau lake evolution more than 10 000 data of chloride content from the paleogene sediments of the endorheic qaidam basin have been collected to monitor changes in lake paleosalinity results show that there were two prominent salinity increase events in the paleogene paleolake one in the late eocene 40 ma and the other in the transition from the eocene to oligocene eot 35 5 ma the first salinity increase event was evidenced by the expansion of saline water the connection of two previous separated saline centers and the deposition of thick bedded halite in a local sag which correlated with the late eocene s frequently fluctuated climate the other salinity increase event at the eot was characterized by the expansion of mesosaline water range which corresponded well to the drier condition of the oligocene icehouse climate the synchronous migration of the saline centers and depocenters demonstrates that the qaidam basin was a tectonically active saline basin where the activity of main faults controlled the occurrence and disappearance of supersaline center under the overall brackish background the deposition of over 200 m thick bedded halite during the late eocene in a local sag was the result of coupled effects by active tectonics and fluctuated climate

high chloride concentrations in the soil and groundwater under an oak hedge in the west of france an indicator of evapotranspiration and water movement chloride is a major anion in soil water and its concentration rises essentially as a function of evapotranspiration compared to herbaceous vegetation high transpiration rates are measured for isolated trees shelterbelts or hedgerows this article deals with the influence of a tree hedge on the soil and groundwater cl concentrations and the possibility of using cl as an indicator of transpiration and water movements near the tree rows cl concentrations were measured over 1 year at different depths in the unsaturated zone and in the groundwater along a transect intersecting a bottomland oak hedge we observed a strong spatial heterogeneity of cl concentrations with very high values up to 2 g l 1 in the unsaturated zone and 1 2 g l 1 in the upper part of the groundwater this contrasts with the low and homogeneous concentrations 60 70 mg l 1 in the deeper part of the groundwater cl accumulation in the unsaturated zone at the end of the vegetation season allows us to identify the active root zone extension of trees in winter upslope of the tree row downwards leaching partly renews the soil solution in the root zone while the slow water movement under the trees or farther downslope results in cl accumulation and leads to a salinization of the soil and groundwater this salinization is of the same order as experimental conditions produce negative effects on oak seedlings the measurement of cl concentrations in the unsaturated zone under tree rows at the end of the vegetation season would indicate whether certain topographic pedological or climatic conditions are likely to favour a strong salinization of the soil as observed in the present study copyright 2009 john wiley sons ltd

a new stage 3 millennial climatic variability record from a sw france speleothem abstract we present a new high resolution speleothem stable isotope record from the villars cave sw france that covers part of marine isotope stage mis 3 the vil14 stalagmite grew between 52 and 29 ka the 13c profile is used as a palaeoclimate proxy and clearly shows the interstadial substages 13 12 and 11 the new results complement and corroborate previously published stalagmite records vil9 and vil27 from the same site the vil14 stalagmite chronology is based on 12 th u dating by mc icp ms and 3 by tims a correction for detrital contamination was done using the 230th 232th activity ratio measured on clay collected in villars cave the vil14 results reveal that the onset of dansgaard oeschger do events 13 and 12 occurred at 49 8 ka and 47 8 ka respectively within uncertainties this is coherent with the latest northgrip time scale gicc05 60 ka and with speleothem records from central alps our data show an abrupt 13c increase at the end of do events 14 to 12 which coincides with a petrographical discontinuity probably due to a rapid cooling as observed for vil9 and vil27 vil14 growth significantly slowed down after 42 ka and finally stopped 29 ka ago where the 13c increase suggests a strong climate deterioration that coincides with both north atlantic sea level and sea surface temperature drop

the role of recharge and evapotranspiration as hydraulic drivers of ion concentrations in shallow groundwater on everglades tree islands florida usa recently evapotranspiration has been hypothesized to promote the secondary formation of calcium carbonate year round on tree islands in the everglades by influencing groundwater ions concentrations however the role of recharge and evapotranspiration as drivers of shallow groundwater ion accumulation has not been investigated the goal of this study is to develop a hydrologic model that predicts the chloride concentrations of shallow tree island groundwater and to determine the influence of overlying biomass and underlying geologic material on these concentrations groundwater and surface water levels and chloride concentrations were monitored on eight constructed tree islands at the loxahatchee impoundment landscape assessment lila from 2007 to 2010 the tree islands at lila were constructed predominately of peat or of peat and limestone and were planted with saplings of native tree species in 2006 and 2007 the model predicted low shallow groundwater chloride concentrations when inputs of regional groundwater and evapotranspiration to recharge rates were elevated while low evapotranspiration to recharge rates resulted in a substantial increase of the chloride concentrations of the shallow groundwater modeling results indicated that evapotranspiration typically exceeded recharge on the older tree islands and those with a limestone lithology which resulted in greater inputs of regional groundwater a sensitivity analysis indicated the shallow groundwater chloride concentrations were most sensitive to alterations in specific yield during the wet season and hydraulic conductivity in the dry season in conclusion the inputs of rainfall underlying hydrologic properties of tree islands sediments and forest structure may explain the variation in ion concentration seen across everglades tree islands copyright 2012 john wiley sons ltd

irregular glacial interstadials recorded in a new greenland ice core the greenland ice sheet offers the most favourable conditions in the northern hemisphere for obtaining high resolution continuous time series of climate related parameters profiles of 18o 16o ratio along three previous deep greenland ice cores1 3 seemed to reveal irregular but well defined episodes of relatively mild climate conditions interstadials during the mid and late parts of the last glaciation but there has been some doubt as to whether the shifts in oxygen isotope ratio were genuine representations of changes in climate rather than artefacts due to disturbed stratification here we present results from a new deep ice core drilled at the summit of the greenland ice sheet where the depositional environ ment and the flow pattern of the ice are close to ideal for core recovery and analysis the results reproduce the previous findings to such a degree that the existence of the interstadial episodes can no longer be in doubt according to a preliminary timescale based on stratigraphic studies the interstadials lasted from 500 to 2 000 years and their irregular occurrence suggests complexity in the behaviour of the north atlantic ocean circulation

loess of southern south america abstract loess and loessoid loess like reworked loess sediments extend across the chaco pampean plains and the nw mountain environments of argentina and in neighbouring countries paraguay brazil uruguay bolivia loessoid sediments are much more abundant than primary loess the beginning of the loessoid sedimentation cycle was related to a phase of late miocene orogeny in the andes the plio pleistocene record is mostly composed of loessoid sediments modified by pedogenesis which produced welded palaeosols the late pleistocene holocene loess record reveals a heterogeneous composition across the region coarse textures and an andean derived volcanic composition prevail in the southern pampas finer textures and material coming from the andes and the other two sources sierras pampeanas and the parana basin characterize the loess deposits of the northern pampas and the eastern chaco a southern patagonian source is also suggested for the mountain valley loess of tucuman although a western andean provenance has been proposed it is believed that the material in the western chaco was derived from the bolivian andes loess deposition was related to a multistage transport mechanism involving fluvial and aeolian processes inferred westerly and southwesterly wind directions as dominant carriers of the aeolian deposits are in agreement with westerly palaeowind simulations using climate models however the role played by westerly tropospheric winds and northerly winds remains to be established

late quaternary vegetational and climatic changes in the pampa grassland of argentina abstract the vegetation and climate of the pampa grassland argentina during the late quaternary are reconstructed from pollen recovered from dated stratigraphic sections from arroyo walls and from archaelogical excavations prior to 10 500 yr b p herbaceous psammophytic steppe existed in the central part of the pampa grassland while xerophytic woodland associated with psammophytic and halophytic steppe occurred in the southwestern part of the pampa these types of vegetation and the continental conditions that prevailed in the area of the present day coast 38 s indicate subhumid dry climate and annual precipitation 100 mm lower than present a subsequent change toward a vegetation characteristic of ponds swamps and foodplains or toward environments with locally more effective moisture occurred ca 10 500 yr b p suggesting annual precipitation close to modern levels or a higher availability of water in the central part of the pampa grassland this type of vegetation existed until 8000 yr b p when it was replaced by grassland communities that lasted until 7000 yr b p in the southwestern part of the pampa grassland this vegetation developed before 7000 yr b p and persisted until ca 5000 yr b p sea level higher than the present ca 6200 yr b p is consistent with sharp modification of the vegetation and development of local halophytic communities dominant at 38 s a return to subhumid dry conditions occurred after 5000 yr b p the late holocene vegetation is characterized by pollen assemblages similar to the psammophytic and halophytic communities of the southern pampa grassland associated with communities with more edaphic conditions at the same time at 38 s a sea level regression is suggested by the dominance of fresh water pollen assemblages and micropaleontological remains the trend toward humid temperate conditions ca 1000 yr b p suggested by vertebrate remains characteristic of temperate and humid conditions as well as a very short but dry episode during the 18th century suggested by the geology are not clearly evidenced in the pollen sequences vegetational and climatic changes are explained by the latitudinal shifts and changes in intensity of the southern atmospheric circulation and changes in sea level

hydrochemistry of pampasic ponds in the lower stream bed of salado river drainage basin argentina chemical analyses of major ions were performed in some of the pampasic ponds in the lower stream bed of salado river drainage basin results indicated that total dissolved solids had a mean value of 1341 mg l where sodium was the most abundant of the cations 80 2 and chloride 44 2 and bicarbonate 37 4 were the predominant anions saturation index showed oversaturation with respect to calcite and dolomite since groundwater is the main source of surface water high sodium concentration in the ponds may be explained by a cation exchange process in the loessic sediments of the basin where calcium is replaced by sodium

groundwater and soil chemical changes under phreatophytic tree plantations 1 the onset of groundwater consumption by plants can initiate a pathway of chemical inputs from aquifers to ecosystems typically absent in groundwater recharge areas we explored this biogeochemical transfer and its influence on soils in phreatophytic eucalypt plantations and native grasslands of the pampas argentina groundwater and soil chemical observations at three grassland plantation pairs were complemented with more detailed analyses along a 400 m long grassland plantation transect although tree plantations showed a widespread and homogeneous salinization of groundwater and soils at all study sites chemical contrasts between the plantation edge and core were evident along the study transect nonsalty slightly acidic bicarbonate dominated waters in the grassland changed sharply within the plantation with dissolved chloride sulfate calcium and magnesium peaking at the plantation core 200 m away from the grassland and dissolved sodium carbonate bicarbonate and ph peaking toward the edge 0 50 m away from the grassland and declining toward the core in agreement with these differences soil alkalinization was the strongest at the plantation edge but absent in the core groundwater flow simulations using flownet suggested trajectories of increasing length and depth and older groundwater ages confirmed by tritium analyses toward the plantation core explaining the hydrochemical contrasts within the plantation flow simulations and chloride mass balances suggested discharges of 250 500 mm yr 1 to the plantations in our sites phreatophytic discharge controlled solute transfers from groundwater through 1 altered flow within the aquifer affecting solute transport to the rooting zone and 2 water uptake plus solute exclusion concentrating solutes in the rooting zone while the first mechanism may be restricted to the core of large phreatophytic areas the second is likely to occur more generally in phreatophytic ecosystems

carbon transfer dynamics from bomb 14c and δ13c time series of a laminated stalagmite from sw france modelling and comparison with other stalagmite records twenty two ams 14c measurements have been made on a modern stalagmite from sw france in order to reconstruct the 14c activity history of the calcite deposit annual growth laminae provides a chronology up to 1919 a d results show that the stalagmite 14c activity time series is sensitive to modern atmosphere 14c activity changes such as those produced by the nuclear weapon tests the comparison between the two 14c time series shows that the stalagmite time series is damped its amplitude variation between pre bomb and post bomb values is 75 less and the time delay between the two time series peaks is 16 years 3 a model is developed using atmosphere 14c and 13c data fractionation processes and three soil organic matter components whose mean turnover rates are different the linear correlation coefficient between modeled and measured activities is 0 99 these results combined with two other stalagmite 14c time series already published and compared with local vegetation and climate demonstrate that most of the carbon transfer dynamics are controlled in the soil by soil organic matter degradation rates where vegetation produces debris whose degradation is slow the fraction of old carbon injected in the system increases the observed 14c time series is much more damped and lag time longer than that observed under grassland sites the same mixing model applied on the 13c shows a good agreement r2 0 78 between modeled and measured stalagmite 13c and demonstrates that the suess effect due to fossil fuel combustion in the atmosphere is recorded in the stalagmite but with a damped effect due to som degradation rate the different sources of dead carbon in the seepage water are calculated and discussed

enhanced chlorophyll associated with island induced cyclonic eddies in the eastern channel of the tsushima straits the relationship between island induced cyclonic eddies and chlorophyll a chl a was investigated using field data and satellite images in the eastern channel of the tsushima straits the maximum chl a concentration around the leeward eddy of the tsushima islands was two or three times greater than that of outside the eddy two different mechanisms of chl a enhancement associated with island induced cyclonic eddies were found in the post bloom periods in summer when nutrients were depleted in the surface layer eddy pumping increased the nutrient supply in the euphotic zone resulting in enhanced chl a around the shallow thermocline near the eddy core in late autumn when the mixed layer deepened over the euphotic zone the mixed layer depth became shallow due to the doming effect of the cyclonic eddy therefore the improved irradiance condition led to an increase in the chl a concentration in the surface mixed layer nighttime satellite visible images showed a number of fishing vessels in the lee region of the tsushima islands implying that the enhanced phytoplankton biomass may have resulted in good feeding conditions for fishes and squids in the tsushima straits

evidence for massive discharges of icebergs into the north atlantic ocean during the last glacial period sediments in the north atlantic ocean contain a series of layers that are rich in ice rafted debris and unusually poor in foraminifera1 here we present evidence that the most recent six of these heinrich layers deposited between 14 000 and 70 000 years ago record marked decreases in sea surface temperature and salinity decreases in the flux of planktonic foraminifera to the sediments and short lived massive discharges of icebergs originating in eastern canada the path of the icebergs clearly marked by the presence of ice rafted detrital carbonate can be traced for more than 3 000 km a remarkable distance attesting to extreme cooling of surface waters and enormous amounts of drifting ice the cause of these extreme events is puzzling they may reflect repeated rapid advances of the laurentide ice sheet perhaps associated with reductions in air temperatures yet temperature records from greenland ice cores appear to exhibit only a weak corresponding signal moreover the 5 10 000 yr intervals between the events are inconsistent with milankovitch orbital periodicities raising the question of what the ultimate cause of the postulated cooling may have been

chronology and paleoenvironment of marine isotope stage 3 from two high elevation speleothems austrian alps abstract a new high resolution stable isotope record from the alpine kleegruben cave 2165 m central alps is presented this record largely duplicates a previously reported speleothem record from this site high precision u series thermal ionization mass spectrometry dates constrain the growth history of this new sample 56 48 ka to the marine isotope stage mis 3 both stalagmites reveal highly similar variations in o isotopes that can be directly compared to o isotope variability associated with dansgaard oeschger interstadials recorded in the greenland ice cores greenland interstadials gis based on the new record we refine our previous age assignments of the gis during this time interval i e gis 15b at 55 7 ka gis 15a at 55 3 ka onset mid point of the prominent gis 14 at 54 5 yr and onset of gis 12 at 48 ka the overall uncertainties associated with these ages are 0 1 0 3 ka the timing of these dansgaard oeschger interstadials is within 0 2 ka of the newly proposed grip sfcp04 timescale the age data for both kleegruben stalagmites demonstrate that liquid water was at least seasonally present in the shallow sub surface allowing calcite precipitation to continue even during stadials of mis 3 given the present day low temperature 2 4 c we propose that these unusual speleothems formed in a karst system overlain by a warm based glacier

microdepression focused recharge in a coastal wetland la plata argentina depression focused recharge dfr has been well documented for the clay till plains of western canada kettle lakes of southeastern wisconsin the sandhills region of nebraska and elsewhere in this study the importance of dfr in a fine grained estuarine coastal plain environment with extremely low topographic relief is shown the southwestern coastal plain of the rio de la plata near the city of la plata argentina extends 8 9 km inland from the river and ranges in elevation from 0 to 3 m above sea level the holocene postpampeano sediments predominantly composed of silty clay in the study area mantle the coastal plain and exert a major control on the hydrodynamics of groundwater of the region the average hydraulic conductivity of the unit ranges from 1 0 10 9 m s 1 when estimated on a small scale single well and oedometer tests to approximately 1 0 10 8 m s 1 when estimated on a larger scale tritium profiles and seepage meters a study of the groundwater flow system has established that recharge is occurring in the marshes of the central coastal plain which are 0 5 1 0 m lower than the surrounding land a broad 50 cm high groundwater mound a significant feature in the context of a regional hydraulic gradient of 0 0005 was documented below the marshland using nests of monitoring wells recharge rates are further controlled by subtle 10 40 cm elevation variations within the marsh four nests of six monitoring wells each were installed in the marsh and sampled for tritium recharge rates were then estimated through calibration simulations using a 1 d analytical solute transport model in the two nests in the lower wetter areas recharge rates were estimated at 4 6 cm year 1 whereas estimated recharge rates in the higher drier areas ranged from 0 3 cm year 1 these differences are consistent with 1 near neutral vertical hydraulic gradients in higher areas vs persistent downward gradients in lower areas 2 chloride concentrations almost an order of magnitude lower in groundwater underlying lower areas than in that of higher areas due to flushing of older more saline groundwater in the lower areas and 3 isotopic evidence for evapotranspiration only in the higher areas the present study suggests that ponding of surface water in local depressions can lead to significant recharge from coastal wetlands this finding has implications for the study of water balance soil salinity and nutrient budgets in these environments 1997 elsevier science b v all rights reserved

european climatic response to millennial scale changes in the atmosphere ocean system during the last glacial period abstract pollen foraminifer dinocyst and coarse lithic high resolution analyses and 18 o measurements have been carried out for the last glacial section of marine core md95 2042 located near the southwestern margin of the iberian peninsula the pollen data indicate a high frequency of vegetational changes on the adjacent continent during this period suggesting a climatic variability very similar to that of the dansgaard oeschger cycles recorded by the greenland ice cores the detailed direct correlation of the terrestrial and marine proxy data from core md95 2042 indicates a three phase pattern of heinrich events in land and ocean environments the first and last phases of the h5 and h4 events are characterized by a mild and humid climate in southwestern europe probably associated with the european origin of the ice rafted detritus the middle phase exhibits a cold and dry climate in iberia linked with the maximum input of ice rafted detritus this phase seems to correspond with the laurentide ice sheet surges between the heinrich events several cold and dry periods on land are correlated with stades of the dansgaard oeschger cycles the impact of the dansgaard oeschger stades in southwestern europe seems to be preferentially connected to the cold winter air masses reaching this mid latitude region