tentative correlation of pollen records of the last interglacial at grande pile and ribains with marine isotope stages eemian lake deposits in grande pile and ribains france correlate with marine isotope substages mis 5e and 5d as delimited in two pollen bearing deep sea cores off portugal the eemian forests in france lasted for approximately 20 millennia from at least 126 000 to ca 107 000 yr b p oscillatory climate deteriorations began about 115 000 yr ago an intense cold spell affected the region approximately 110 000 yr ago

biogenic silica record of the lake baikal response to climatic forcing during the brunhes abstract this work presents a detailed orbitally tuned biogenic silica record of continental paleoclimate change during the brunhes chron the brunhes matuyama boundary lies within the warm isotopic stage 19 in baikal and the boundaries between eight lithological cycles correspond to terminations in the marine oxygen isotope record the high amplitude and resolution of climatically driven changes in biosi content in lake baikal sediments permits tuning of almost every precessional cycle during the brunhes and reveals the structure of interglacial stages for example the last three interglacial stages mis 5 7 and 9 clearly consist of five substages a b c d e corresponding to precessional insolation peaks abrupt and intense regional glaciations in siberia during substages 5d and 7d were driven by extreme insolation minima during substage 9d cooling was more gradual in response to more moderate forcing the impact of strong glaciation is also observed in the middle of stage 15 where full glacial conditions appear to have lasted for over 30 000 yr during substages 15d 15c and 15b marine oxygen isotopic stage 11 appears to be the warmest period during the brunhes in the lake baikal record with at least three substages a new hypothesis is presented regarding the response of the lake baikal biosi record to insolation forcing based on the mechanism controlling modern diatom blooms biogenic silica production is hypothesized to be dependent on changes in the heat balance of the lake and consequently on changes in the thermal structure of the water column this mechanism is also sensitive to short term sub milankovich cooling events such as the mid eemian cooling the montaigu event during substage 5c and a cooling which appears to be analogous to the montaigu event during substage 9c the continuity of the lake baikal paleoclimate record its sensitivity to orbital forcing and its high resolution make it an excellent candidate for a new paleoclimatic stratotype section for continental asia

two step deglaciation at the oxygen isotope stage 6 5e transition the zeifen kattegat climate oscillation comparison of marine lacustrine and terrestrial records from twenty four sites suggests the existence of a younger dryas type climate oscillation just prior to the oxygen isotope stage 6 5e boundary these records include results from biostratigraphic pedostratigraphic and speleothem studies as well as analyses of stable isotope compositions of marine records and ice cores the climate oscillation is named after the warm zeifen interstadial and the cold kattegat stadial the zeifen interstadial may be related to a major meltwater pulse in the baffin bay labrador sea norwegian sea region the climate oscillation is presumably in part a result of a variation in ocean circulation especially in the strength of the north atlantic drift but changes in the atmospheric circulation also played an important role the geographically widespread distribution of the oscillation suggests that the two step deglaciation influenced both the northern and southern hemispheres c 1996 elsevier science ltd

stalagmite evidence for the onset of the last interglacial in southern europe at 129 1 ka multi proxy data from an italian stalagmite constrain the commencement of full last interglacial conditions in southern europe at 129 1 ka consistent with absolutely dated records currently available from both hemispheres the post glacial transition towards warmer and wetter conditions commenced at 134 2 ka oxygen isotope evidence suggests this was interrupted briefly at 130 2 ka an event probably related to the termination ii pause associated with heinrich event 11 for most of the stalagmite the pattern of delta 18 o variation mimics the air temperature record from the vostok ice core especially through marine isotope stage 5 there is no obvious evidence for substantial early interglacial warming

the eemian interglaciation in northwestern germany abstract hundreds of small lakes became filled with eemian deposits following the retreat of saalian ice in northwestern germany weakly expressed climate oscillations have been inferred from some local pollen records of late saalian sediments sea level stood 7 m below the current northwest german sea level datum nn during the interglacial climate optimum and decreased afterward a uniform vegetational succession of the eemian mixed forests correlated with marine isotope stage mis 5e terminated with the demise of boreal woodlands marked by a steep increase in nonarboreal pollen this is the onset of the early weichselian herning stade correlated with mis 5d no sharp climate oscillations during the eemian have been documented in the ending phase of the interglaciation the climate deteriorated gradually dominant heath and grass tundras point to a substantial decline of summer temperature during the herning stade sea level then stood at 40 m nn sedimentological considerations supported by counts of partly varved deposits indicate that the eemian lasted about 10 000 11 000 yr and the herning for several millennia

diatom and geochemical evidence of mid to late holocene climatic changes at lake holzmaar west eifel germany abstract changes in diatom assemblages geochemistry and stable carbon isotope composition of bulk organic matter in a varved sediment section from lake holzmaar west eifel germany were used to infer mid to late holocene climatic changes and human impact from 6340 to 1470 cal yr bp shifts in total lacustrine primary production were derived from 13 c org values changes in non siliceous algae biomass productivity were deduced from accumulation rates of organic matter diatom valve accumulation rates and biogenic opal accumulation rates were used as proxies for diatom productivity and for siliceous phytoplankton abundance respectively based on weighted averaging of relative diatom abundance in subsamples qualitative changes in past trophic status were inferred accumulation rates of minerogenic material and the toc tn molar ratio permitted the deduction of past changes in allochthonous matter influx diatom assemblage composition showed statistically significant changes around 5130 3660 and 2900 cal yr bp whereas planktonic diatom productivity was subject to distinct shifts around 5900 5130 4500 3600 2660 and approximately 1630 cal yr bp and siliceous phytoplankton biomass changed ca 6100 4500 2660 1900 and 1700 cal yr bp causally determined changes in diatom assemblage composition and productivity for example due to shifts in nutrient ratios and or concentrations invoked by changes in lake circulation patterns precipitation rates and or erosion rates are discussed glacier fluctuations and lake level changes reported from other study sites in western europe support the finding that reconstructed lacustrine processes are at least indirectly linked to climate palynological and archaeological evidence however has shown a strong superimposition of lacustrine processes with local regional anthropogenic activity since the iron age

climate variations in europe over the past 140 kyr deduced from rock magnetism rapid shifts in climate during the last glacial are now well documented particularly from the oxygen isotope records of the two greenland ice cores grip1 2 and gisp23 in the grip record1 2 these climate events are also seen during the preceding eemian interglacial which may be an analogue for the future climate warmed by the greenhouse effect but these shifts are not found in the eemian section of the gisp2 core3 casting doubt on whether the rapid shifts in the grip oxygen isotope record really do represent a climate signal here we present magnetic susceptibility pollen and organic carbon records from maar lake deposits in the massif central france these data provide an independent record of past climate and we find that they correlate well with the ice core records during the last glacial during the eemian two rapid cooling events seen in our record also correlate with those seen in the grip ice core supporting the idea that rapid climate change did occur in the eemian interglacial and demonstrating that it extended to continental europe

eocene arc petrogenesis in central chile c 33 6 s and implications for the late cretaceous miocene andean setting tracking the evolving tectonic regime the scarce eocene geological record in the andean region of central chile c 33 6 s is represented by the estratos del cordon de los ratones unit this is a c 450 m thick mainly volcanic continental series with a bimodal character that hosts numerous subvolcanic intrusions the igneous products show compositional features indicating a co genetic character for the whole suite relatively juvenile mantle signatures and arc like affinities this along with age determinations of c 42 ma indicate that the unit corresponds to the middle eocene arc in the region the geochemical data obtained complement the evolving arc magmatic record throughout andean evolution this allows us to track 1 the earliest late cretaceous orogenic event 2 neutral tectonic conditions from the latest cretaceous to mid eocene times 3 the oligocene early miocene extensional episode and 4 the onset of the prevailing compression the record also indicates that the extensional event started no earlier than the mid eocene with the deposition of the estratos del cordon de los ratones and no later than the earliest oligocene in addition orogenic processes developed from early miocene times are highlighted relative to those developed during the early late cretaceous at least in the arc region supplementary material analytical methods item 1 the full dataset of u pb age determinations by shrimp item 2 and la icp ms item 3 and additional geochronological diagrams item 4 are available at https doi org 10 6084 m9 figshare c 4710305

an analysis of eemian climate in western and central europe on the basis of 31 pollen diagrams and additional data for botanical macrofossils an analysis is made of the last interglacial eemian climatic history in western and central europe the main tool for this analysis is the climatic indicator species method only selected woody species are used for the quantification of data partial climatic range diagrams are presented for abies alba acer monspessulanum acer tataricum buxus sempervirens tilia tomentosa the problem of time correlation and pollen zonation of the eemian is discussed the climatic analysis itself is based on an improved version of the indicator species method in this version not every site is analysed for its climatic values instead maps and tables on the migrational history of hedera ilex buxus abies and species of acer tilia and abies are the basis for climatic maps showing respectively january and july isotherms for the periods of the corylus zone e4a and the carpinus zone e5 it is concluded that mean january temperatures were as much as 3 c higher at amsterdam the netherlands than at present and mean temperatures in july were 2 c higher however the thermal maximum in winter was later zone e5 than the summer thermal maximum zone e4a winter temperatures changed parallel to rise and fall of global sea level precipitation changes are more difficult to estimate in the first part of the eemian precipitation must have been relatively low but from zone e4b onward it increased to higher values reaching 800 mm and probably substantially more in zones e5 and e6 hence the eemian climate was in its beginning relatively more contintental and later from e4b onward more oceanic however as compared with the holocene the eemian climate was generally speaking more oceanic

interactions of climate and land use documented in the varved sediments of seebergsee in the swiss alps this paper presents a multiproxy high resolution study of the past 2600 years for seebergsee a small swiss lake with varved sediments at the present tree line ecotone the laminae were identieed as varves by a numerical analysis of diatom counts in the thin sections the hypothesis of two diatom blooms per year was corroborated by the 210 pb and 137 cs chronology a period of intensive pasturing during the little ice age between ad 1346 and ad 1595 is suggested by coprophilous fungal spores as well as by pollen indicators of grazing by the diatom inferred total phosphorus by geochemistry and by documentary data the subsequent re oligotrophication of the lake took about 88 years as determined by the timelag between the decline of coprophile fungal spores and the restoration of pre eutrophic nutrient conditions according to previous studies of latewood densities from the same region cold summers around ad 1600 limited the pasturing at this altitude this demonstrated the socio economic impact of a single climatic event however the variance partitioning between the effects of land use and climate which was applied for the whole core revealed that climate independent of land use and time explained only 1 32 of the diatom data while land use independent of climate and time explained 15 7 clearly land use ineuenced the lake but land use was not always driven by climate other factors beside climate such as politics or the introduction of fertilizers in the seventeenth and eighteenth centuries also ine uenced the development of alpine pasturing

influence of terrestrial vegetation on sediment forming processes in kettle lakes of west central minnesota the composition magnetic characteristics and pollen content of sediments from two small kettle lakes near the prairie forest border in west central minnesota were used to infer changes in terrestrial vegetation shoreline erosion eolian inputs carbonate deposition and aquatic productivity several important changes in sediment stratigraphy coincide closely with changes in the terrestrial pollen assemblage accumulation rates of organic inorganic and carbonate sediment fractions as well as the concentration of magnetic particulates increased abruptly as prairie replaced pine forest and decreased gradually throughout the subsequent transitions to oak scrub and later mixed woodland results suggest that by its mediation of wind exposure local vegetation may affect 1 influx of eolian particulates 2 erosion of shorelines 3 water circulation and 4 carbonate equilibria in addition low rates of accumulation of organic matter and increased humidicity during periods of conifer vegetation suggest that humic matter leached from forest soils may influence lake water chemistry and reduce productivity changes in lake level caused by differential rates of evapotranspiration of the various vegetation types conifer forest deciduous hardwood forest brush scrub and prairie could not be detected sediment forming processes can therefore be altered by changes in local terrestrial vegetation through several mechanisms that are independent of changes in lake level

global ice volume fluctuations north atlantic ice rafting events and deep ocean circulation changes between 130 and 70 ka multiproxy data from north atlantic deep sea sediment core neap18k provide a detailed record of climate through oxygen isotope stage ois 5 seven distinct large scale episodes of ice rafting c25 c19 were identified between 126 and 70 ka global ice volume reconstructions based on high resolution benthic 18 o records indicate that major ice rafting events were not confined to ice volume maxima at ois 5d and 5b but also occurred during periods of ice sheet growth and disintegration however iceberg discharges were restricted to times when sea levels were 40 65 m below present values ice rafting episode c25 the first large scale cooling of mid atlantic surface waters after the last interglacial occurred during the gradual buildup of continental ice sheets at the ois 5e 5d transition major ice sheet collapses allied to ice rafting events c24 and c21 were associated with rapid sea level increases of 20 and 40 m respectively suborbital climatic fluctuations in the neap18k sedimentary record denoted by prominent 7 5 4 5 and 3 k y cyclicities appear to correlate with both greenland atmospheric temperatures and changes in thermohaline circulation patterns inferred from benthic 13 c values and hence provide clear evidence of a highly interconnected north atlantic climatic regime during ois 5

high resolution record of northern hemisphere climate extending into the last interglacial period high resolution record of northern hemisphere climate extending into the last interglacial period

insolation regime in siberia as a major factor controlling diatom production in lake baikal during the past 800 000 years abstract a unique diatom biostratigraphy of the brunhes chron in lake baikal revealed by detailed studies of pelagic diatom paleo assemblages indicates that dramatic changes in insolation during the past 800 ka bp produced surprisingly rapid diatom speciation and extinctions the orbitally tuned age model allows the diatom assemblages to be compared with individual marine isotopic stages and substages during the brunhes most of the interglacial periods are characterized by explosive speciation and appearances of new pelagic planktonic diatom species in contrast most of the glacial periods are characterized by spectacular extinctions three broad periods characterized by different degrees of stability in the pelagic diatom assemblages are distinguished during the brunhes chron in the lake baikal sedimentary record mis 19 15e mis 15a 11 and mis 9 5 these periods are apparently associated with the long term changes in the amplitude of precessional insolation variations examination of individual interglacial periods further reveals the sensitivity of the baikal ecosystem to the regional energy balance virtually every precessional insolation peak during the early brunhes is characterized by a unique and peculiar paleo assemblage for the first time the siliceous microfossil record has demonstrated such a high degree of sensitivity to insolation forcing of regional climate despite the dramatic changes in the pelagic plankton driven by extreme climatic changes diatoms never went fully extinct during any glacial period although greatly or completely renewed during each subsequent interglacial the pelagic diatom assemblage still managed to return dominated by the new baikal endemic species the diatom assemblage observed in modern lake baikal despite being mostly endemic has formed during the past 50 100 ka and is therefore rather young these results demonstrate the remarkable capacity of this large freshwater system to sustain the dynamic stability on the large time scales

the classic marine isotope substage 5e since its identi cation nearly fty years ago marine iso tope stage 5 mis 5 has been placed onto absolute time scaleson the basis of three independent approaches cesare emiliani who set up the isotope stages emiliani 1955 depended onuranium series dating of the sediments a method that today isregarded as not generally capable of yielding useful precisionor accuracy broecker and van donk 1970 pioneered the ap proach of correlating to radiometrically dated marine coral ter races thishasbeenmuchaidedinrecentyearsbyimprovementsin the precision and accuracy of these age determinations thathave owed from the development of thermal ionization massspectrometry tims for uranium series dating edwards

timing and duration of last interglacial conditions in europe a chronicle of a changing chronology abstract estimates of the length of the last interglacial in europe conventionally defined by the presence of forest as inferred from pollen diagrams have varied considerably here an account of recent developments largely instigated by a paper by kukla et al 1997 is presented these include the emergence of new records with improved chronologies and a re evaluation of previous assumptions of synchroneity between marine and terrestrial stage boundaries and also between northern and southern european changes the current scheme proposes that the onset of the last interglacial in europe started well into mis 5e after deglaciation was complete and was coincident with a rise to peak sea surface temperatures however the timing of the end of the last interglacial between northern and southern europe appears to have diverged considerably in the north the elimination of forest occurred ca 115 ka near the time of the mis 5e 5d transition while in the south tree populations persisted into the interval of global ice growth until the onset of significant ice rafting ca 110 ka this significant n s diachroneity may be a reflection of the effects of different bioclimatic parameters limiting tree growth in the two areas these developments highlight the problems of correlating records of different proxies and from different geographical regions

a high resolution 11 400 yr diatom record from lake victoria east africa abstract fine interval 30 45 yr sampling of a core from lake victoria s damba channel shows that numerous abrupt changes in the lake s diatom assemblages have occurred in response to climatic fluctuations over the past 11 400 14 c yr four distinct climatic phases bounded by sudden transitions are inferred 1 variably dry 11 400 10 000 yr b p 2 humid 10 000 7200 yr b p 3 more seasonal 7200 2200 yr b p and 4 more arid 2200 0 yr b p with a dry little ice age event 600 200 yr b p the diatom inferred paleoclimatic history for northern lake victoria closely resembles that inferred from a well dated pollen record from pilkington bay spectral analysis of the diatom record reveals strong periodicities including globally distributed 2360 2550 1400 1030 1130 and 500 cal yr cycles repeated rapid shifts between aulacoseira and nitzschia dominated diatom assemblages suggest that post 1960 changes in the lake s phytoplankton communities have had earlier climate driven analogs

stable climatic conditions in central germany during the last interglacial stable isotopic data from the high resolution limnic sequence in the opencast mine at grobern central germany confirm the relatively stable climate of the last interglacial deduced from pollen analyses after significant warming during the transition from the saalian to the eemian stable warm climatic conditions set in once the climatic optimum was reached in the course of biozones e4 to e5 from the middle of biozone e6b a gradual temperature decrease can be observed reaching a minimum at the start of biozone e7 the division of the early weichselian glacial in central germany into two stadials herning rederstall and two interstadials brorup odderade is also documented by the findings copyright 2000 john wiley sons ltd

submillennial environmental fluctuations during marine oxygen isotope stage 2 a comparative analysis of diatom and pollen evidence from lago grande di monticchio south italy high temporal resolution pollen and diatom analyses carried out on sediments from lago grande di monticchio span the interval 23 700 21 200 calendar yr bp a brief interstadial during marine oxygen isotope stage 2 both records exhibit marked changes that are interpreted as responses to climatic changes the diatoms and terrestrial vegetation appear to respond at the same time any relative lag in the response of the vegetation was less than the ca 60 yr resolution of the two records the interval coincides at least in part with the campo imperatore stade when the gran sasso ice sheet reached its maximum extent and water level was high in the fucino lake correlation of the marked environmental oscillation with one of the dansgaard oeschger events recorded by stable oxygen isotope records from the greenland ice cap is proposed this follows an interval interpreted as having a cold dry climate and correlated with a heinrich event in the north atlantic together the two records enable a multifactorial interpretation of the palaeoclimate changes that characterise the oscillation providing additional insight to that obtained from studies of ice and ocean sediment cores especially with respect to the seasonality of temperature and precipitation copyright 1999 john wiley sons ltd

similarity of vegetation dynamics during interglacial periods the velay sequence france provides a unique continuous palynological record spanning the last four climatic cycles a pollen based reconstruction of temperature and precipitation displays marked climatic cycles an analysis of the climate and vegetation changes during the interglacial periods reveals comparable features and identical major vegetation successions although marine isotope stage mis 11 3 and the holocene had similar earth precessional variations their correspondence in terms of vegetation dynamics is low mis 9 5 7 5 and especially 5 5 display closer correlation to the holocene than mis 11 3 ecological factors such as the distribution and composition of glacial refugia or postglacial migration patterns may explain these discrepancies comparison of ecosystem dynamics during the past five interglacials suggests that vegetation development in the current interglacial has no analogue from the past 500 000 years

rock magnetic properties of eemian maar lake sediments from massif central france a climatic signature the hypothesis of a climate variability within the last interglacial eemian suggested by oxygen isotope data of a greenland ice core grip was later supported by magnetic susceptibility organic matter and pollen signatures in the eemian lake sediments of the lac du bouchet france in the present paper we analyse in detail the rock magnetic properties of these sediments in order to determine the origin of the magnetic susceptibility variations furthermore in order to verify the empirical relation between magnetic susceptibility and climate we studied two eemian sequences from neighbouring lakes lac st front and ribains maar lake rock magnetic investigations mainly consisted of analyses of anhysteretic and isothermal remanent magnetizations along with hysteresis measurements carried out on pilot samples lac du bouchet susceptibility variations are at least partly affected by postdepositional magnetite dissolution lac st front sediments show a complex behaviour resulting in partly contradicting interpretations of rock magnetic parameters possible explanations may be the presence of a very fine grained magnetite or the presence of maghemite ribains maar lake sediments show a homogeneous magnetic mineralogy without major variations in most of the rock magnetic parameters susceptibility records of the three lakes were compared under the simplified assumption that magnetic susceptibility mainly reflects variations of the detrital titano magnetite input only a poor correlation between the three eemian susceptibility sequences is observed suggesting that local effects including dissolution and dilution effects may have altered the original detrital climatic signal the purely detrital origin of the lac du bouchet eemian susceptibility variations must thus be questioned but it nevertheless appears to be the only lake whose susceptibility variations can tentatively be correlated with the grip eemian oxygen isotope record

abrupt temperature changes in the western mediterranean over the past 250 000 years a continuous high resolution western mediterranean sea surface temperature sst alkenone record spanning the past 250 000 years shows that abrupt changes were more common at warming than at cooling during marine isotope stage mis 6 sst oscillated following a stadial interstadial pattern but at lower intensities and rates of change than in the dansgaard oeschger events of mis 3 some of the most prominent events occurred over miss 5 and 7 after prolonged warm periods of high stability climate during the whole period was predominantly maintained in interglacial interstadial conditions whereas the duration of stadials was much shorter

high resolution palynological record off the iberian margin direct land sea correlation for the last interglacial complex abstract we present high resolution pollen dinocyst and isotopic data for the last interglacial complex from marine core md952042 southwestern margin of the iberian peninsula 37 48 n 10 10 w 3148 m direct land sea correlation from this core indicates that during this period north atlantic sea surface temperatures were in phase with iberian climate our palynological analysis suggests a younger dryas like event at the marine isotope stage mis 6 5 transition the analysis also indicates that the eemian spans from the lightest isotopic values of mis 5e ca 126 ky bp to the heavier isotopic values towards the mis 5e 5d transition therefore the eemian is not entirely equivalent to mis 5e pollen analysis identifies four climatic phases of low amplitude during the eemian a mediterranean climate in southwestern europe is gradually replaced by oceanic conditions the middle of the eemian is characterized by an increase in precipitation on the land and ocean associated with a slight cooling this seems to be the result of a displacement of the polar front as far south as southern europe during this period after the eemian three relatively short climatic phases on land melisey i st germain ia and montaigu cold event occurred contemporaneously with three shifts of sea surface temperatures the montaigu event first identified in terrestrial pollen sequences is therefore also recorded in core md952042 on the basis of pollen dinocyst and planktonic isotopic data our results also show that the warm periods of mis 5 are not characterized by similar climatic conditions on land

a diatom record for the past 400 ka from lake biwa in japan correlates with global paleoclimatic trends abstract detailed diatom records from a 140 m sediment core with a time resolution of approximately 1000 1500 yr were obtained from lake biwa to examine possible correlations between diatom concentrations and paleoclimatic changes during the last approximately 400 ka in the sediments the diatom assemblages are generally dominated by planktonic diatoms the diatom stratigraphy is characterized by four zones with distinctly higher concentration values and 12 horizons with low concentration values diatom records from the 140 m core and another core indicate that these changes were not local phenomena but occurred throughout the lake basin comparison of diatom concentration records with pollen records from lake biwa sediments indicates that higher diatom concentrations represent warmer and wetter climatic conditions and that lower concentrations represent colder and drier climatic conditions comparison of diatom records from lake biwa with marine oxygen isotopic records shows that the number of peaks and their relative amplitudes are similar in both profiles therefore peaks and drops in diatom concentration profile might correlate with most oxygen isotopic events this finding indicates that during approximately the last 400 ka the changes in diatom concentration represented as diatom productivity in lake biwa correlate closely with global paleoclimatic changes at the scale of the milankovitch cycle precession cycles of 23 and 19 ka and that diatom concentration was higher during warm events and lower during cold or cooling events

stalagmite evidence for the precise timing of north atlantic cold events during the early last glacial evidence of millennial scale cold events following the last interglacial are well preserved in north atlantic marine cores greenland ice and pollen records from europe however their timing was previously undetermined by radiometric dating we report the first precise radiometric ages for two such events c23 105 1 0 9 ka to 102 6 0 8 ka and c24 112 0 0 8 ka and 108 8 1 0 ka based on stable carbon and oxygen isotope measurements on a stalagmite from italy cc28 in addition to providing new information on the duration of these events in southern europe the age data provide invaluable tuning points for the melisey i c24 and montaigu c23 pollen zones identified in western europe the former event is of particular significance because it represents the end of the eemian interglacial forest phase in western europe the new age data will also allow fine tuning of the timing and duration of greenland stadial 24 equivalent to c23 in the north greenland ice core project ice core and via a common gasage chronology tuning of the vostok and epica european project for ice coring in antarctica ice cores

continental climate response to orbital forcing from biogenic silica records in lake baikal changes in insolation caused by periodic changes in the earth s orbital parameters provide the primary forcing for global ice ages1 6 but it is not clear to what extent the climates in continental interiors are controlled directly by regional variations in insolation and to what extent they are driven instead by the highly nonlinear response of the oceans and ice sheets here we investigate this question using the record of biogenic silica in lake baikal as a proxy for climate change in this high latitude mid continental region we find a good correlation between this record and that of marine oxygen isotopes4 over the past 250 kyr the baikal record exhibits both a strongly nonlinear component manifested in a 100 kyr periodicity and weaker direct insolation components manifested in the 41 kyr obliquity and 23 and 19 kyr precession orbital cycles these results show that even though extreme continental climates such as this are influenced directly by insolation variations they are dominated by the nonlinear rhythm of the oceans and ice sheets

deconstructing terminations i and ii revisiting the glacioeustatic paradigm based on deep water temperature estimates benthic and planktonic oxygen isotope 18occ and mg ca analyses in two cores from the northeast atlantic have permitted the reconstruction of surface and deep water temperature tdw and 18o 18ow variations across the last two deglaciations these records allow the timing of de glacial melt water pulses reaching the northeast atlantic to be compared with the evolution of local deep water tdw 18ow conditions although each glacial termination is unique in detail a similar pattern of hydrographic change is reconstructed for both deglaciations with the first major decrease in deep water 18ow due to sea level and or purely local deep water change occurring in parallel with the onset of intensely cold glacial surface water temperatures and prior to a terminal ice rafting and melt water event the evolution of deep water across both de glaciations involved two transient incursions of cold low 18o water into the deep northeast atlantic the second of which was particularly pronounced each time these pulses of cold deep water are interpreted to reflect the incursion of water directly analogous to modern antarctic bottom water aabw and containing a significant component of brine rejected during sea ice formation the results presented here show that the same type of transient changes in deep water circulation that occurred across termination i also occurred across termination ii and that as a result of these deep ocean changes the timing of each benthic 18o termination cannot precisely reflect the timing of de glacial sea level change as many palaeoceanographic interpretations and some controversies are prone to assume such imprecision in timing especially may well extend to marine isotope stage mis boundaries in general as a principle of hydrographic variability and its expression in the geological record

diatom responses to limnological and climatic changes at ribains maar french massif central during the eemian and early wurm abstract high resolution diatom analysis was carried out to assess the limnological and climatic changes that took place at ribains maar french massif central during the late pleistocene 131 105 ka bp with a focus on the eemian interglacial in particular numerical analyses were used to show that most of the variability in the fossil diatom assemblages was due to climate independently from the changes in the lake catchment vegetation as represented by pollen data diatom based quantitative reconstructions of the past limnological conditions as well as a comprehensive literature review on the auto ecological requirements for the principal diatom taxa were used to interpret the record an absolute time scale for the sequence was derived by matching the major pollen shifts with the radiometrically dated changes in oxygen isotopes observed in italian stalagmites this study shows that at ribains maar the transition from the riss saalian glacial to the eemian interglacial was marked by a gradual increase in the contribution of spring blooming diatom species indicating a longer growing season and milder winter spring conditions at that time a short cooling event interrupts this trend and may correspond to a stadial at the start of the eemian a peak in benthic taxa and the suppression of spring blooming flora probably reflects the effects of deglaciation on the catchment during the eemian interglacial itself three main phases were distinguished within the diatom record the first phase 8000 years in duration was dominated by stephanodiscus minutulus which suggests that intense mixing in the water column took place during spring the pollen record was simultaneously dominated by quercus and corylus that typify this phase as the climatic optimum of the eemian the second phase almost equal in duration to the first phase 7000 years is generally dominated by cyclotella taxa and suggests a less productive lake and much reduced period of spring mixing compared with the first phase in the pollen diagram this corresponds to an interval dominated by carpinus picea abies that indicates a cooler and wetter climate the third and last phase of the eemian 2000 year long saw the return to stephanodiscus dominated assemblages indicating a warming that may correspond to the dansgaard oeschger event 25 identified in the greenland ice core record in the early stage of the wurm glacial weichselian assemblages in the melisey i stadial 3000 year long were dominated by either aulacoseira subarctica or asterionella formosa which suggest colder spring conditions than during the late eemian but not as cold as the ones indicated by the pollen record stephanodiscus spp again dominate during the saint germain ia interstadial 5000 year long suggesting a return to the conditions that prevailed before the melisey stadial in agreement with the pollen record the record ends with the montaigu cold event which is characterised by a pinus peak in the pollen record and corresponds to a large abundance of a subarctica in the diatom sequence throughout the eemian the abundance of stephanodiscus spp which is thought to be driven by winter conditions show cyclic fluctuations that most likely match the cooling events identified in a pollen record from germany variation in insolation throughout the eemian may have been the driving factor behind the species succession observed in the diatom sequence while this study demonstrates that diatom analysis of lake sediment can provide very detailed information on long term climate change a review of the few other diatom investigations published on european eemian deposits shows that this technique has been so far seldom used to its full potential in this context in central and southern europe

eemian crustal deformation in the eastern baltic area in the light of the new sites at peski russia and pohja uhtju estonia abstract several eemian mikulino marine deposits are known from the northwestern part of russia and from estonia the best known deposits are situated at mga russia and at prangli estonia two new sites with clayey and silty deposits covered by till were studied for pollen and diatoms at peski russia and pohja uhtju estonia at peski the deposit representing the eemian interglacial is 3 8 m thick at the depth of 13 4 9 6 m above present sea level at pohja uhtju the deposit representing the eemian is 3 5 m thick at the depth of 47 9 51 4 m below present sea level although peski is situated at a higher altitude than pohja uhtju at present the diatom stratigraphy at these sites indicates deeper and more saline conditions in the peski area than at pohja uhtju during the eemian this result is similar to some previous studies which indicate that although the russian deposits e g peski mga are now at a higher altitude than those in estonia pohja uhtju and prangli the diatoms in the russian deposits are indicative of a considerable depth of water during the time of deposition these deposits suggest that the eemian shore levels ascend from estonia eastwards while the late weichselian and holocene shorelines tilt downwards in the same general direction the present material from estonia and northwestern part of russia shows marked differences between the eemian and late weichselian holocene crustal deformations which probably resulted from different ice loads during the final glaciation phases and probably also from different deglaciation patterns during the saalian and late weichselian

relation of subtropical atlantic temperature high latitude ice rafting deep water formation and european climate 130 000 60 000 years ago abstract a new high resolution record of sea surface temperature from the subtropical western north atlantic documents a series of abrupt coolings within marine isotope stage 5 which can be objectively correlated with marine core evidence for increased ice sheet discharge at subpolar latitudes and reduced north atlantic deep water formation these results indicate that ice sheet forcing of deep ocean circulation influenced surface temperatures over much of the north atlantic a proposed correlation to the pollen record of grande pile france indicates that each cold event seen in the pollen sequence has a unique counterpart in the record of subtropical ocean temperature if this correlation is correct it suggests that the warmest part of the european eemian ended suddenly in response to oceanographic changes and that the subsequent post temperate phase of the eemian extended well into the interval of ice sheet growth corresponding to marine isotope substage 5d

hydrography and mollusc faunas of the baltic and the white sea north sea seaway in the eemian abstract palynologically dated mollusc and cirriped faunas from a region extending from the north sea through the baltic and karelia to the arkhangelsk region show that the hydrography of the baltic was very different from the holocene for 2 2 5 ka in the early eemian a seaway existed from the barents to the north sea through karelia until it was severed at the present continental watershed to the north of lake onega after this the ladoga onega trough remained an arm of the baltic for several millennia the benthic faunas are comparable to the holocene but their boundaries were displaced much further into the baltic notable differences from the holocene are the absence or rarity of the macoma balthica biocoenosis and the presence of cold portlandia dominated biocoenoses in karelia in the belt sea and western baltic winter sea surface temperatures and salinity were higher than now by ca 6 c and 15 and the distinctly brackish top layer was missing at the same time cold bottom water 2 5 c with a tendency to anoxia characterised the karelian arm of the baltic water exchange through this area was inhibited by the constriction to the north of lake onega and the basin and threshold bathymetry water transport through the white sea baltic seaway was too sparse to play an active role in the north atlantic surface circulation or climatic change in the region the high salinity and temperature in the belt sea and western baltic persisted throughout the eemian and are explained by wider and deeper passage from the north sea to kattegat wider straits through denmark higher salinity in the north sea higher evaporation as well as more dispersed fresh water supply the advection of oceanic water into the baltic culminated in the early eemian before the carpinus zone and probably resulted in an oceanic climate in the baltic region while at the same time cold winters produced cold bottom water in the karelian arm

a long pollen record from lac du bouchet massif central france for the period ca 325 to 100 ka bp ois 9c to ois 5e abstract pollen analysis was carried out on sediments older than the wurm pleniglacial ois 4 in two new sequences h and i derived from the centre of lac du bouchet massif central the inferred vegetation history enables for the first time in france five temperate episodes to be defined which pre date the last interglacial these temperate episodes alternate with episodes during which the changes in vegetation are indicative of glacial climates comparison of these climatic episodes with the oceanic isotope record shows that the pollen record of sequences h and i from lac du bouchet spans the time interval from ois 9c ussel interstadial to ois 5e ribains eemian interglacial in the organic sediments from the amargiers interstadial ois 9a a trachytic layer ar ar dated to ca 275 ka enables a correlation to be established with the upper part of a sequence derived from the nearby praclaux crater the lower part of this sequence being of holsteinian age ois 11c the cross dating of the pollen sequences from lac du bouchet cores h i and d and from praclaux provides a complete record from the massif central southern france of successive glacial and interglacial episodes that span the last ca 400 ka that is the interval from the holsteinian to the holocene

the last climatic cycle at la grande pile vosges france a new pollen profile a new pollen diagram has been made from an old unanalyzed core from la grande pile gp xx correlations with the previous work of woillard 1975 1978 leads to the following conclusions the end of the eemian was marked by a minor climatic change prior to the melisey i stadial the ognon ii and ognon iii interstadials are not consistent and correspond to the level of reworking of mesophilous taxa during the last pleniglacial the limitations of the botanical interpretation of pollen spectra from the last pleniglacial are underlined lastly bruckenthalia and larix are identified for the first time at la grande pile the respective roles of these taxa following the eemian are additional arguments for correlating the st germain i and ii with the early weichsel interstadials in the north of middle europe

rissian eemian and wurmian coleoptera assemblages from la grande pile vosges france abstract the grande pile peat bog sequence is one of the few west european sites that cover the entire time span of the last major climatic cycle 140 000 years a recent program of coring has provided material for insect analysis the aim of this palaeoentomological study is to interpret the environmental and climatic evolution from the end of the rissian glaciation to the holocene using subfossil coleoptera the studied samples yielded 394 taxa of coleoptera half of them identified to species level 19 of which do not belong to the present day french fauna the large number of taxa suggests a wide variety of habitats and provides much detailed palaeoecological evidence for the period studied the lowermost sediments of the sequence corresponding to the end of the rissian glaciation were deposited under very cold conditions in a tundra environment this is succeeded by a forest period in which two cool interludes of grassland environment occur although these periods are decidedly poor in tree dependent coleoptera they do not contain any really cold adapted taxa they divide the forest phase into three periods the first one corresponding to the eemian interglacial shows an early stage in which the beetle fauna is characterized by species dependent on deciduous trees a later stage in which this fauna is mixed with many conifer dependent elements some of which e g platypus oxyurus suggest warmer and perhaps wetter climatic condition than today the two later woodland periods yielded coleopteran assemblages rather similar to those recorded in the second part of the eemian i e with both deciduous and conifer dependent taxa there is some evidence to suggest that these two periods were slightly cooler than the eemian proper marked climatic deterioration becomes obvious in the upper half of the sedimentary sequence attributed to the last glacial period wurm with the reappearance of tundra beetle assemblages sediment and insect evidence suggest that the climate was extremely cold and continental at la grande pile at about 30 000 b p a comparison of the insect analysis with previous palynological works enables precise correlation between the results provided by these two independent approaches however large numbers of running water coleoptera in the forest periods replaced by standing water coleoptera in cold periods raise questions concerning the lacustrine origin of the sedimentation at la grande pile

problems of the duration of the eemian interglacial in europe north of the alps abstract suggestions that the duration of the eemian interglacial was about 11 000 yr based on annually laminated sediment sequences in germany have been challenged in favor of a much longer interval however biostratigraphic evidence demonstrates why the eemian sequences at grande pile and ribains cannot be reliably used for alignment with the marine sequence as applied by kukla et al 2002 this issue to estimate the duration of this interglacial the long chronology they propose would imply not just coniferous but for up to 5000 yr fully temperate forest in central france coexisting with treeless heath and steppe tundra conditions in northwestern europe an unlikely climatic and ecological scenario the proposal that the eemian interglacial in western europe lasted for 17 000 or even 23 000 yr is rejected a duration of no more than 13 000 yr is preferred at least for sites north of the alps and pyrenees the duration of temperate conditions in the mediterranean region is less certain

eemian to early wurmian climate dynamics history and pattern of changes in central europe abstract high resolution pollen records from the northern alpine foreland are used to evaluate the patterns of climate change during the period between the late eemian interglacial marine oxygen isotope stage ois 5e about 115 ky ago and the end of the st germain ii ois 5a dansgaard oeschger interstadial d o is21 about 75 ky ago for the quantitative climate interpretation of the fossil pollen assemblages we compare two different methods a modern analogue technique and a mutual climatic range approach the results not only reveal major climatic changes at the transition to stadials and interstadials but also indicate short term oscillations which are followed by an almost full return to the preceding climate conditions and components of gradual trends resembling saw tooth structures based on the pollen data the climate reconstructions suggest that the optimum in st germain ii ois 5a d o is21 in winter temperatures was about 0 8 to 1 4 c and in summer temperatures about 0 7 to 1 2 c warmer than the optimum in st germain i ois 5c d o is22 to is24 the severe and short time montaigu cold event iceberg discharge event c23 clearly divided st germain i into two thermal periods thus st germain ia d o is24 preceding the montaigu event is slightly more favourable than the following st germain ic d o is23 since several climate oscillations occurred during these interstadials they show only limited stability with respect to the stadial periods the results reveal a coherent pattern for all records winter temperatures during melisey ii ois 5b c21 are about 1 to 4 c lower than those during melisey i ois 5d c24 as regards short term climate changes during melisey i and melisey ii consistent amelioration episodes may be distinguished during these intervals

lake baikal record of continental climate response to orbital insolation during the past 5 million years the sedimentary record of biogenic silica from lake baikal in south central siberia suggests that this region of central asia was impacted by two major cooling episodes at 2 8 to 2 6 and 1 8 to 1 6 million years ago the spectral evolution of this continental interior site parallels the evolutionary frequency spectra for various marine oxygen isotope records in the baikal record the 41 000 year obliquity cycle is particularly strong from 1 8 to 0 8 million years ago variance in the 100 000 year eccentricity band increases during the past 0 8 million years the expected precession frequency of 23 000 years is highest during the past 400 000 years the modulation of the predicted 23 000 and 41 000 year insolation forcing by the 100 000 and 400 000 year eccentricity bands indicates that the transfer of variance from the precession and obliquity frequencies to the eccentricity part of the spectrum occurred in the eurasian continental interior as well as in tropical and high latitude ocean sites

north atlantic current and european environments during the declining stage of the last interglacial this paper provides a tentative reconstruction of environmental shifts in europe associated with changes of the north atlantic current and related meridional sea surface temperature sst gradients during most of the eemian interglacial ca 126 115 ka the north atlantic current extended far north into the nordic seas and european environments were comparable to those of the holocene however ca 115 ka an sst drop in the nordic seas marked a southward displacement of the north atlantic current this hydrographic shift was associated with substantial cooling in northern europe and drier conditions in the mediterranean region the polar timberline retreated southward from 69 n in northernmost scandinavia to 52 n in central europe and thermophilous deciduous trees became extinct north of the 48th parallel woodlands persisted in southern europe for another 5 k y well into marine isotope substage 5d these conditions indicate steep vegetation and climate gradients at the inception of the last glacial

a time domain recursive method to analyse transient wave propagation across rock joints the present investigation is concerned with transient wave propagation in a rock mass with a set of parallel joints by using a recursive method according to the displacement field of a rock mass with a set of parallel joints the interaction between four plane waves two longitudinal waves and two transverse waves and a joint is analysed first with the displacement discontinuity model and the time shifting function the wave propagation equation based on the recursive method in time domain for obliquely longitudinal p or transverse s waves across a set of parallel joints is established the joints are assumed linearly elastic the analytical solution obtained by the proposed method is compared with the existing results for some special cases including oblique incidence across a single joint and normal incidence across a set of parallel joints by verification it is found that the solutions by the proposed method match very well with the existing methods the applicability and limitations of the new method are then discussed for incident waves with different properties

eemian lake development hydrology and climate a multi stratigraphic study of the hollerup site in denmark abstract a classic northwest european open section with lacustrine eemian sediments hollerup has been studied with respect to sedimentology geochemistry stable isotopes diatoms and mineral magnetic analyses and correlated by geochemistry and diatoms to a previously pollen analysed section by andersen 1965 this correlation has enabled the section to be related to muller s 1974 tentative eemian absolute chronology and shows that the hollerup eemian sediments appear to cover c 11 000 yr our studies show that the onset of the eemian was characterized by a major lake level rise followed by an almost 3000 yr long period of high but oscillating lake levels it is argued that the latter part of this period of highly maritime climate can be defined as the eemian climatic optimum this period was interrupted by a few hundred years long phase of low lake level coinciding with the immigration of spruce followed by medium high lake levels the next c 3500 yr coinciding with the carpinus pollen zone seem to have been characterized by fairly humid and mild conditions although slightly more arid than during the preceding optimum the carpinus period ended with a more than 1000 yr long gradual lake level fall and this period of lake level change concurring with the transition into the pinus pollen dominated period terminated with an extreme low lake level event this 300 500 yr long arid phase coincides with a distinct peak in pine pollen and was followed by higher but slightly oscillating lake levels in a cooler climate the end of the eemian seems to have been characterised by a gradual cooling until almost pure clastic sedimentation and a marked expansion of herb pollen grains mark the onset of the weichselian based on regional correlations to other european terrestrial and north atlantic marine proxy records we argue that the distinct hydrologic and climatic events displayed in the hollerup record were possibly caused by a combination of sea level changes changes in the hydrologic cycle and changing oceanic circulation patterns the latter two may have been triggered by the opening and closure of the baltic sea white sea connection the initial build up of continental ice sheets and the first major impacts of meltwater induced freshwater in key areas for thermohaline circulation

benthic foraminiferal and stable isotope evidence for a younger dryas style cold spell at the saalian eemian transition denmark abstract benthic foraminiferal and stable isotope studies of two borings from the island of anholt denmark reveal a continuous late saalian eemian sequence with an overall gradual warming interrupted by a short term temperature deterioration comparable with the younger dryas cold spell the sequence is correlated to the global deep sea stable isotope record based on environmental evidence given by foraminiferal faunas and stable isotopes the following environmental changes in the anholt cores can be attributed to the global variations 1 1 an interstadial phase the flakket interstadial which had a duration of about 1000 years is correlated to stable isotope event 6 01 2 2 the following cold spell the kattegat stadial spanning about 1000 years represents most of the interval between isotope events 6 01 and 6 0 3 3 a phase of rapid warming within about 1000 years bsotope events 6 0 and 5 53 4 4 a sea level change within the eemian between isotope events 5 53 and 5 51

suborbital climate variability during marine isotopic stage 5 in the central mediterranean basin evidence from calcareous plankton record abstract new faunal and floral records from ocean drilling project hole 963a resolved at 80 year spacing provide evidence of suborbital scale climate variability in the central mediterranean sea throughout marine isotope stage mis 5 cold events in the central mediterranean sea indicated by low abundances of warm species and high abundances of cold species are also evident in a planktonic foraminifera paleoclimatic curve they have been linked to ngrip greenland ice core c events and appear correlative with similar sub millennial climate fluctuations identified in the north atlantic region and in the alboran basin westernmost mediterranean low resolution benthic and planktonic oxygen isotope fluctuations parallel trends in the surface records evidenced by planktonic assemblage fluctuations bolstering their interpretation as climate proxies climate events also occur in the mediterranean between named c events and may be coeval with additional climate events identified recently in the western subtropical atlantic hence we propose that frequent climate oscillations during mis 5 characterize both sides of the mid latitude north atlantic perhaps indicating millennial scale variations in mid latitude atmospheric patterns

evolution and demise of the last interglacial warmth in the subpolar north atlantic detailed faunal isotopic and lithic marine records provide new insight into the stability and climate progression of the last interglacial period marine isotope stage mis 5 which peaked approximately 125 000 years ago in the eastern subpolar north atlantic at the latitude of ireland interglacial warmth of the ice volume minimum of substage 5e mis 5e lasted 10 000 years 10 ka and its demise occurred in two cooling steps the first cooling step marked the end of the climatic optimum which was 2 3 ka long minor ice rafting accompanied each cooling step the second larger step encompassing cold events c26 and c25 was previously identified in the northwestern atlantic approximately 41c of cooling occurred between peak interglacial warmth and c25 and the region experienced an additional temporary cooling of at least 1 21c during c24 a cooling event associated with widespread ice rafting in the north atlantic beginning with c24 mis 5 was characterized by oscillations of at least 1 21c superimposed on a generally cool baseline the results of this study imply that the marine climatic optimum of the last interglacial was shorter than previously thought the finding that the eastern subpolar north atlantic cooled significantly before c24 reconciles terrestrial evidence for progressive climate deterioration at similar and lower latitudes with marine conditions our results also demonstrate a close association between modest ice rafting cooling and deep ocean circulation even during the peak of mis 5e and in the earliest stages of ice growth