rates and possible causes of neotectonic vertical crustal movements of the emerged southeastern united states atlantic coastal plain emerged pliocene and pleistocene shorelines and associated marine deposits were used to determine the magnitude and rate of vertical crustal movement during the past 3 m y in the united states atlantic coastal plain of south and north carolina on the basis of a new regional ostracode assemblage zonation planktic biostratigraphic data and radiometric data emerged marine deposits were determined to be primarily interglacial and can tentatively be correlated with hemispheric warm intervals in evidence from deep sea data the paleontologic evidence indicates a primary glacio eustatic component to the local sea level record and a secondary tectonic component net vertical uplift rates averaging 1 to 3 cm 1 000 yr but perhaps as high as 5 to 10 cm 1 000 yr are in evidence for the emerged coastal plain although details of the timing of regional rheological events remain obscure the trend of net uplift contrasts with general subsidence rates of about 2 to 4 cm 1 000 yr since the cretaceous in submerged parts of the continental margin near subsiding sedimentary troughs hydro isostatic crustal response to multiple deglaciation events may have periodically uplifted the coast but long term lithospheric flexural upwarping in response to sediment loading offshore is a more plausible mechanism to explain the present positions of shorelines above present mean sea level a eustatic sea level model is proposed for interglacial high stands of the past 3 0 m y

cosmic ray labeling of erosion surfaces in situ nuclide production rates and erosion models a number of in situ cosmogenic radionuclides and stable nuclides have been measured in natural exposed rock surfaces with a view to study their in situ production and rock erosion rates 1 the in situ radionuclides can be used for a high resolution tomography of the erosional history of an exposed surface two stable nuclides 3he 21ne and five radionuclides 10be 26al 36cl 14c 39ar having half lives in the range of 300 1 5 106 yr half life are measurable in many rock types a prerequisite for the application of the in situ nuclides for the study of erosional histories of surfaces is a knowledge of their production rates under different irradiation conditions altitude latitude irradiation geometry and shielding relative nuclide production rates can be determined fairly accurately using the extensive available data on cosmic ray neutrons 2 absolute nuclide production rates cannot generally be predicted with any accuracy because of lack of data on excitation functions of nuclides unless some normalization is possible as was done in the case of several cosmic ray produced isotopes in the atmosphere 3 based on a recent natural calibration experiment in which erosion free surfaces exposed to cosmic radiation for 11 000 yrs were sampled the absolute production rates of 10be and 26al in quartz have been accurately estimated for mountain altitudes in sierra nevada 4 the absolute production rates of 10be and 26al in quartz can therefore be estimated fairly accurately for any given latitude and altitude some measurements of 14c in rocks of low erosion rate 5 similarly allow an estimate of its production rate attempts made to measure the in situ production rates of 3he in rocks have not yet led to a convergent production rate in view of the importance of knowing the production rates of isotopes of he ne and ar i present here theoretical estimates of their production rates based on available cross section data i discuss the information that can be extracted from the study of the in situ nuclides in rocks useful parameters characterizing the exposure history of a rock surface are 1 the effective surface exposure age and 2 the time averaged erosion rate the implications of these parameters for single and multiple nuclide studies are discussed in terms of the erosion models considered

the magnitude and rapidity of the climate change marking the end of the pleistocene in the mid latitudes of south america abstract the chi squared test of independence and cluster analysis of otsuka similarity coefficients of fossil beetle assemblages from the chilean lake region in the mid latitudes of south america support the following conclusions 1 the mean summer temperature of the glacial climate was 4 5 c lower than today s climate 2 the climatic change from glacial to interglacial mode was in a single step centered on about 14 000 yr b p 3 the climatic change was rapid and within 1500 years the biota of a moorland had been completely replaced by a biota of a rain forest 4 by 12 500 yr b p the low elevation beetle fauna of the chilean lake region was similar in composition to that of the present day and 5 no reversal in the postglacial warming trend equivalent in age to the younger dryas stade was detected

340 000 year centennial scale marine record of southern hemisphere climatic oscillation in order to investigate rapid climatic changes at mid southern latitudes we have developed centennial scale paleoceanographic records from the southwest pacific that enable detailed comparison with antarctic ice core records these records suggest close coupling of mid southern latitudes with antarctic climate during deglacial and interglacial periods glacial sections display higher variability than is seen in antarctic ice cores which implies climatic decoupling between mid and high southern latitudes due to enhanced circum antarctic circulation structural and temporal similarity with the greenland ice core record is evident in glacial sections and suggests a degree of interhemispheric synchroneity not predicted from bipolar ice core correlations

depositional processes on an ancient and modern muddy shelf northern california the modern eel river shelf and analogous pleistocene rio dell formation in northern california provide an ideal opportunity to combine the advantages of studying a modern environment with those of studying an ancient sequence and thereby enables further understanding of muddy shelf processes the modern shelf is the site of accumulation of a thick deposit of holocene mud both large scale sediment distribution patterns and small scale stratigraphy on the shelf indicate that river floods play an important role in sediment accumulation even on a high energy storm dominated coast the major factors in preservation of this flood signature are the cohesive behaviour of fine grained sediments and episodically rapid rates of sediment input the rio dell formation includes approximately 400 m of mostly fine grained shelf deposits that accumulated offshore from a palaeo eel river mouth the shelf sediments comprise four depositional sequences sequence 1 records progradation from outer to inner shelf depths facies trends closely resemble across shelf trends on the modern shelf suggesting that processes were similar detailed examination of these deposits provides insight into the nature and role of various processes on both the ancient and modern shelf muddy facies of the rio dell sequence are characterized by bioturbated clayey silts interbedded with event layers of several types clay rich silt layers are interpreted as flood deposits and physically stratified coarse silt layers are interpreted to record transport and deposition of coarse silt on the midshelf during storms sediment transport calculations and consideration of grain size distributions of bioturbated sediments which form the bulk of the rio dell sequence suggest that these sediments are the result of biological homogenization of the fine grained flood deposits and of the coarser grained storm deposits the results of this study in general indicate that fine grained shelf deposits do preserve a distinguishable if subtle record of depositional processes

the deglaciation of the americas during the last glacial termination this paper reviews current understanding of deglaciation in north central and south america from the last glacial maximum to the beginning of the holocene together with paleoclimatic and paleoceanographic data we compare and contrast the pace of deglaciation and the response of glaciers to major climate events during the global last glacial maximum glgm 26 5 19 ka average temperatures decreased 4 to 8 c in the americas but precipitation varied strongly throughout this large region many glaciers in north and central america achieved their maximum extent during the glgm whereas others advanced even farther during the subsequent heinrich stadial 1 hs 1 glaciers in the andes also expanded during the glgm but that advance was not the largest except on tierra del fuego hs 1 17 5 14 6 ka was a time of general glacier thickening and advance throughout most of north and central america and in the tropical andes however glaciers in the temperate and subpolar andes thinned and retreated during this period during the bolling allerod interstadial b a 14 6 12 9 ka glaciers retreated throughout north and central america and in some cases completely disappeared many glaciers advanced during the antarctic cold reversal acr 14 6 12 9 ka in the tropical andes and patagonia there were small advances of glaciers in north america central america and in northern

thin fine grained storm layers in a muddy shelf sequence an example from the lower jurassic in the stenlille 1 well denmark thin storm sand layers are a characteristic feature of many sandy shelf sequences while little evidence of storm layers is preserved in muddy shelf deposits where bioturbation is often total the present study shows that storm generated depositional processes governed sedimentation in a muddy shelf environment the studied sequence is dominated by blackish mudshale and silt streaked mudshale with thinner intervals of pale fine grained heterolithic sandstone it represents the lower jurassic fjerritslev formation in the eastern part of the danish basin and has been studied in four cores from the stenlille 1 well within the muddy outer shelf association four sedimentary facies and 14 types of laminae 0 5 10 mm thick may be distinguished most of the laminae share the characteristics of graded bedding erosive bases and occasional fading ripples with storm layers of sand grade the structures indicate that the mudshale laminae formed by settling of the suspension load carried by storm generated currents this kind of episodic deposition of fine grained storm layers may be common though rarely preserved in outer shelf environments

radiocarbon chronology of the late glacial puerto bandera moraines southern patagonian icefield argentina abstract we report radiocarbon dates that constrain the timing of the deposition of the late glacial puerto bandera moraine system alongside the western reaches of lago argentino adjacent to the southern patagonian icefield close maximum limiting radiocarbon ages n 11 for glacier advance into the outer moraines with a mean value of 11 100 60 14 c yrs bp 12 990 80 cal yrs bp were obtained from wood in deformation soft till exposed beneath flow and lodgment till in bahia del quemado on the northeast side of brazo norte north branch of western lago argentino other exposures of this basal deformation till in bahia del quemado reveal incorporated clasts of peat along with larger inclusions of deformed glaciofluvial and lacustrine deposits radiocarbon dates of wood included in these reworked peat clasts range from 11 450 45 14 c yrs bp to 13 450 150 14 c yrs bp 13 315 60 to 16 440 340 cal yrs bp the implication is that during this interval glacier fronts were situated inboard of the puerto bandera moraines with the peat clasts and larger proglacial deposits being eroded and then included in the basal till during the puerto bandera advance minimum limiting radiocarbon ages for ice retreat come from basal peat in cores sampled in spillways and depressions generated during abandonment of the puerto bandera moraines glacier recession and subsequent plant colonization were initiated close behind different frontal sectors of these moraines prior to 10 750 75 14 c yrs bp 12 660 70 cal yrs bp east of brazo rico 10 550 55 14 c yrs bp 12 490 80 cal yrs bp in peninsula avellaneda and 10 400 50 14 c yrs bp 12 280 110 cal yrs bp in bahia catalana in addition a radiocarbon date indicates that by 10 350 45 14 c yrs bp 12 220 110 cal yrs bp the brazo norte lobe or former upsala glacier had receded well up the northern branch of lago argentino to a position behind the herminita moraines furthermore glacier termini had receded to just outboard of the outer holocene moraines at lago frias and lago pearson anita prior to 10 400 40 14 c yrs bp 12 270 100 cal yrs bp and 9040 45 14 c yrs bp 10 210 50 cal yrs bp respectively the most extensive recession registered during the early holocene was in agassiz este valley where the upsala glacier had pulled back behind the outer holocene moraine reaching close to the present day glacier terminus before 8290 40 14 c yrs bp 9300 80 cal yrs bp the radiocarbon dated fluctuations of the lago argentino glacier in late glacial time given here are in accord with changes in ocean mixed layer properties predominately temperature derived from the isotopic record given here of odp core 1233 taken a short distance off shore of the chilean lake district it also matches recently published chronologies of late glacial moraines in the southern alps of new zealand on the opposite side of the pacific ocean from lago argentino finally the timing of the late glacial reversal of the lago argentino glacier fits the most recent chronology for the culmination of the antarctic cold reversal acr in the deuterium record of the epica dome c ice core from high on the east antarctic plateau therefore we conclude that the climate signature of the acr was widespread in both the ocean and the atmosphere over at least the southern quarter of the globe

timing of formation of neoglacial landforms in the south shetland islands antarctic peninsula regional and global implications abstract the timing of neoglacial advances in the antarctic peninsula ap is not yet well constrained accurate temporal reconstruction of neoglaciation in the ap is needed to better understand past glacial responses and regional and global teleconnections during the holocene here we examine all available information about neoglacial advances in the south shetland islands ssi as well as in the broader geographical context of the ap region and antarctic continent in order to shed light on the contrasting chronologies existing for neoglacial advances in these regions we focused on a case study where a detailed picture of the holocene deglaciation was already available lake sediments revealed that byers peninsula west of livingston island ssi was fully deglaciated during the holocene thermal maximum to complement this approach we identified glacially polished bedrock surfaces erratic boulders and a moraine ridge near the present front of the glacier in the se corner we applied cosmogenic ray exposure cre dating using in situ 36cl for basalt rocks and 10be for granitic rocks in i 8 samples from glacial erratic and ice rafted boulders ii 2 samples from moraine boulders iii 2 samples from polished bedrock surfaces and iv 1 sample from an erratic boulder deposited on one of these surfaces the cre dates indicate that the onset of deglaciation started around 9 9 1 2 ka with two phases of glacier expansion during the mid late holocene forming moraines at 4 1 0 5 and 1 0 0 2 ka respectively the main neoglacial advances in the ap and the ssi were mostly synchronous and coincided with cold periods as shown by other records e g glacio isostatic marine terraces marine and lake sediments in addition these periods of glacial expansion show a similar timing to those recorded in the arctic these results suggest that neoglaciation was driven by global climate forcing in both polar areas despite temporal variations at regional and local scale

dust and sea salt variability in central east antarctica dome c over the last 45 kyrs and its implications for southern high latitude climate a detailed record of non sea salt calcium a proxy for dust and sea salt sodium a proxy for sea salt covering the last 45 kyr is presented it shows that in the first part of the transition from the last glacial period to the holocene 18 15 kyr bp the changes in dust flux mainly reflect changes at the dust source namely vegetation cover and local climate the changes in the later part of the transition 12 11 kyr bp are similar in extent to the changes seen in sea salt and most likely reflect a reorganization of the atmospheric circulation during the last glacial period considerable variation of dust but not of sea salt is observed pointing to climatic changes in patagonia the main dust source for dome c a comparison of the glacial records from dome c and taylor dome suggests that similar influences controlled aerosol input at both sites during this period

the anatomy of long term warming since 15 ka in new zealand based on net glacier snowline rise the timing and magnitude of postglacial climatic changes around the globe provide insights into the underlying drivers of natural climate change using geomorphologic mapping of moraines 10 be surface exposure dating snowline reconstructions and numerical modeling we quantified glacier behavior during late glacial 15 11 5 ka and holocene the past 11 5 k y time in the ben ohau range new zealand glaciers were more extensive during the antarctic cold reversal acr than subsequently and the margins underwent a punctuated net withdrawal over the holocene numerical modeling experiments that achieve the best fit to the moraines suggest that air temperature during the acr was between 1 8 c and 2 6 c cooler than today with similar 20 prescribed precipitation after the acr a net snowline rise of 100 m through the younger dryas stadial 12 9 11 7 ka was succeeded by a further long term or net rise of 100 m between 11 k y and 500 yr ago glacier snowline records in new zealand show generally coherent late glacial and holocene climate trends however the paleoclimate record in the southwest pacific region shows important differences from that in the northern hemisphere

cosmogenic 10be and 26al exposure ages of moraines in the rakaia valley new zealand and the nature of the last termination in new zealand glacial systems new zealand glaciers reached their last glacial maximum position at or before 25 ka and as early as 23 ka commenced a slow and continual retreat new cosmogenic exposure ages and field mapping from the rakaia valley in the south island suggest that extensive ice survived well into the latter half of the last glacial interglacial transition 18 11 ka with the post 15 ka period inferred to have near holocene climate conditions based on ecological proxy data by as late as 15 5 ka glacier termini had retreated as little as 5 10 km from glacial maximum positions numerous minor ice still stand positions and oscillations are recognized but the record specifically excludes evidence for either a major climatic amelioration at 15 16 ka or a significant glacial re advance during the antarctic cold reversal acr or the younger dryas yd we conclude that the currently widespread interpretation of an episodic new zealand glacial record since the lgm is an artifact of valley dependent retreat processes pro glacial lake formation and local site conditions combined to give an apparent but misleading picture of glacial retreat punctuated by major climatically driven re advances copyright 2010 elsevier b v all rights reserved

warming and glacier recession in the rakaia valley southern alps of new zealand during heinrich stadial 1 abstract the termination of the last ice age featured a major reconfiguration of earth s climate and cryosphere yet the underlying causes of these massive changes continue to be debated documenting the spatial and temporal variations of atmospheric temperature during deglaciation can help discriminate among potential drivers here we present a 10be surface exposure chronology and glaciological reconstruction of ice recession following the last glacial maximum lgm in the rakaia valley southern alps of new zealand innermost lgm moraines at big ben have an age of 17 840 240 yrs whereas ice marginal moraines or ice molded bedrock surfaces at distances up valley from big ben of 12 5 km lake coleridge 25 km castle hill 28 km double hill 43 km prospect hill and 58 km reischek knob have ages of 17 020 70 yrs 17 100 110 yrs 16 960 370 yrs 16 250 340 yrs and 15 660 160 yrs respectively these results indicate extensive recession of the rakaia glacier which we attribute primarily to the effects of climatic warming in conjunction with geomorphological maps and a glaciological reconstruction for the rakaia valley we use our chronology to infer timing and magnitude of past atmospheric temperature changes compared to an overall temperature rise of 4 65 c between the end of the lgm and the start of the holocene the glacier recession between 17 840 and 15 660 yrs ago is attributable to a net temperature increase of 4 0 c from 6 25 to 2 25 c accounting for 86 of the overall warming approximately 3 75 c 70 of the warming occurred between 17 840 and 16 250 yrs ago with a further 0 75 c 16 increase between 16 250 and 15 660 yrs ago a sustained southward shift of the subtropical front stf south of australia between 17 800 and 16 000 yrs ago coincides with the warming over the rakaia valley and suggests a close link between southern ocean frontal boundary positions and southern mid latitude climate most of the deglacial warming in the southern alps occurred during the early part of heinrich stadial 1 hs1 of the north atlantic region because the stf is associated with the position of the westerly wind belt our findings support the concept that a southward shift of earth s wind belts accompanied the early part of hs1 cooling in the north atlantic leading to warming and deglaciation in southern middle latitudes

a beryllium 10 chronology of late glacial moraines in the upper rakaia valley southern alps new zealand supports southern hemisphere warming during the younger dryas interhemispheric differences in the timing of pauses or reversals in the temperature rise at the end of the last ice age can help to clarify the mechanisms that influence glacial terminations our beryllium 10 10be surface exposure chronology for the moraines of the upper rakaia valley of new zealand s southern alps combined with glaciological modeling show that late glacial temperature change in the atmosphere over the southern alps exhibited an antarctic like pattern during the antarctic cold reversal the upper rakaia glacier built two well defined closely spaced moraines on reischek knob at 13 900 120 1 310 yrs when including a 2 1 production rate pr uncertainty and 13 140 250 370 yrs ago in positions consistent with mean annual temperature approximately 2 c cooler than modern values the formation of distinct widely spaced moraines at 12 140 200 320 and 11 620 160 290 yrs ago on meins knob 2 km up valley from the reischek knob moraines indicates that the glacier thinned by 250 m during heinrich stadial 0 hs 0 coeval with the younger dryas 12 900 to 11 600 yrs ago the glacier inferred temperature rise in the upper rakaia valley during hs 0 was about 1 c because a similar pattern is documented by well dated glacial geomorphologic records from the andes of south america the implication is that this late glacial atmospheric climate signal extended from 79 s north to at least 36 s and thus was a major feature of southern hemisphere paleoclimate during the last glacial termination

the tekapo glacier new zealand during the last glacial maximum an active temperate glacier influenced by intermittent surge activity abstract quaternary glaciations have created impressive landform assemblages that can be used to understand palaeo glacier extent character and behaviour and hence past global and local glacier forcings however in the southern hemisphere and especially in new zealand the quaternary glacial landform record is relatively poorly investigated with regard to glaciological properties in this study a 1 m digital elevation model dem was generated from airborne lidar data and supplemented with aerial imagery and field observations to analyse the exceptionally well preserved glacial geomorphology surrounding lake tekapo new zealand we describe a rich suite of last glacial maximum lgm and recessional ice marginal subglacial supraglacial glaciofluvial and glaciolacustrine landform assemblages these represent two landsystems comprising i fluted till surfaces with low relief push moraine ridges and ii crevasse squeeze ridges zig zag eskers and attenuated lineations the former landsystem records the behaviour of an active temperate glacier and the latter landsystem which is superimposed upon and inset within the former strongly suggests intermittent surge phases the two landsystem signatures indicate a sequential change in ice marginal dynamics during recession that was likely to have been partially non climatically driven overall we present the first evidence of surge type glacier behaviour in new zealand

timing of millennial scale climate change at siple dome west antarctica during the last glacial period using atmospheric methane and the isotopic composition of o2 as correlation tools we place the dd record of ice from the siple dome west antarctica ice core on a precise common chronology with the gisp2 greenland ice core for the period from 9 to 57 ka the onset of major millennial warming events in siple dome preceded major abrupt warmings in greenland and the pattern of millennial change at siple dome was broadly similar though not identical to that previously observed for the byrd ice core also in west antarctica the addition of siple dome to the database of well dated antarctic paleoclimate records supports the case for a coherent regional pattern of millennial scale climate change in antarctica during much of the last ice age and glacial interglacial transition

shelf construction in a foreland basin storm beds shelf sandbodies and shelf slope depositional sequences in the upper cretaceous mesaverde group book cliffs utah the upper cretaceous campanian kenilworth member of the blackhawk formation mesaverde group is part of a series of strand plain sandstones that intertongue with and overstep the shelfal shales of the western interior basin of north america analysis of this section at a combination of small sedimentological and large stratigraphical scales reveals the dynamics of progradation of a shelf slope sequence into a subsiding foreland basin four major lithofacies are present in the upper mancos and kenilworth beds of the book cliffs a lag sandstone and channel fill shale lithofacies constitutes the thin basal transgressive sequence which rests on a marine erosion surface it was deposited in an outer shelf environment shale interbedded sandstone and shale and amalgamated sandstone lithofacies were deposited over the transgressive lag sandstone lithofacies as a wave dominated delta and its flanking strand plains prograded seaward analysis of grain size and primary structures in kenilworth beds indicates that there are four basic strata types which combine to build the observed lithofacies the fine to very fine grained graded strata of the interbedded facies are tempestites deposited out of suspension by alongshelf storm flows geostrophic flows there is no need to call on cross shelf turbidity currents density underflows to explain their presence very fine to fine grained hummocky strata are likewise suspension deposits created by waning storm flows but were deposited under conditions of more intense wave agitation on the middle shoreface cross strata sets in this region are bed load deposits that accumulated on the upper shore face in the surf zone lag strata are multi event bed load deposits that are the product of prolonged storm winnowing they occur on transgressive surfaces while the graded beds are tempestites in the strict sense all four classes of strata are storm deposits the distribution of strata types and their palaeocurrent orientations suggests a model of the kenilworth transport system driven by downwelling coastal storm flows and probably by a northeasterly alongshore pressure gradient the stratification patterns shift systematically from upper shoreface to lower shoreface and inner shelf lithofacies partly because of a reduction in fluid power expenditure with increasing water depth but also because of progressive sorting which resulted in a decrease in grain size in the sediment load delivered to successive downstream environments the kenilworth member and an isolated outlier the hatch mesa lentil constitute a delta prodelta shelf depositional system their rhythmically bedded lenticular sandstone and shale successions are a prodelta shelf facies and may be prodelta plume deposits major upper cretaceous sandstone tongues in the book cliffs are underlain by erosional surfaces like that beneath the blackhawk formation which extend for many tens of kilometres into the mancos shale these surfaces are the boundaries of upper cretaceous depositional sequences the sequences are large scale genetic stratigraphic units they result from the arranging of facies into depositional systems the depositional systems are in turn stacked in repeating arrays which constitute the depositional sequences the anatomy of these foreland basin sequences differs

groundwater surfacewater interactions at the transition of an aquifer from unconfined to confined a three dimensional numerical model is developed to identify systematic changes in the interactions between the groundwater flow systems and streams that cross the transition zone where unconfined aquifers become confined a generalized model is designed that represents hydrologic conditions where gently dipping aquifer confining unit sedimentary sequences subcrop beneath a thin surficial aquifer and are transected by gaining streams flowing parallel to dip a series of simulations are performed to investigate the effect of different hydrogeologic characteristics of the edge of the confining unit where potential for facies changes or fluvial reworking results in variations in the material properties of the confining unit the results show an abrupt increase in groundwater discharge to the stream immediately upstream of the transition to confined conditions and a corresponding but not equal decrease in groundwater discharge along stream reaches downstream of the edge of the confining unit model results were compared to measured stream discharges at a location where the loosahatchie river of eastern tennessee usa crosses an unconfined confined transition in the upper mississippi embayment

resolving aquifer behavior near a focused recharge feature based upon synoptic wellfield hydrogeochemical tracer results aquitard windows are known to occur in unconsolidated aquifer systems and represent areas offocused recharge to otherwise confined underlying aquifers the study herein focused on a known window site affecting the memphis aquifer located in the sheahan wellfield in shelby county tennessee uranium and thorium series radioisotopes were evaluated from production wells sampled in the wellfield and compared to other geochemical characteristics of the system from the research a conceptual model was realized whereby higher uranium concentrations from near surface waters flow through a redox barrier in the aquitard window and become depleted in uranium further 234 u 238 u activity ratio increased downgradient of the recharge source by alpha recoil mobilization of 234 u via 234 th and possibly leaching of uranium bound by iron hydroxides via dissolution and subsequent precipitation by reducing waters flowing to downgradient wells the behavior of the hydrogeochemical tracers could be best described in the conceptual model by normalizing uranium to fe 2c throughout the system the use of the u fe 2c pair provides a useful tool for understanding of the mixing behavior near focused recharge sites with redox barriers and may be useful for developing aquifer behavior models q 2005 elsevier b v all rights reserved

engineering geological studies and tunnel support design at sulakyurt dam site turkey abstract this paper presents the results of engineering geological investigations and tunnel support design studies carried out at the sulakyurt dam site northeast of ankara turkey the sulakyurt dam will be used for flow control and water storage for irrigation projects studies were carried out both in the field and the laboratory field studies include engineering geological mapping intensive discontinuity surveying core drilling and sampling for laboratory testing the diversion tunnel will be driven in rock mass consisting of granite and diorite empirical analytical and numerical methods were combined for safe tunnel design rock mass rating rmr rock mass quality q and geological strength index gsi systems were used for empirical rock mass quality determination site characterization and support design the convergence confinement method was used as analytical method and software called phase 2 a 2d finite element program was utilized as numerical method according to the results acquired from the empirical analytical and numerical methods tunnel stability problems were expected in both granite and diorite rock masses the support system suggested by empirical methods was applied and the performance of suggested support system was evaluated by means of numerical modelling it was concluded that the suggested support systems were adequate since after applying the suggested support system to granite and diorite tunnel deformation and the yielded elements around the tunnel decreased significantly thus it is suggested that for more reliable support design empirical numerical and analytical methods should be combined

changes in the position of the subtropical front south of new zealand since the last glacial period this study fills an important gap in our understanding of past changes in the southern subtropical front s stf in the southwest pacific ocean paleo sea surface temperatures sst were estimated from planktic foraminiferal census counts from cores straddling the modern s stf in the solander trough south of new zealand the estimated sst were compared for 6 time slices glacial period 25 21 ka last glacial maximum lgm 21 18 ka early deglaciation 18 16 ka late deglacial early holocene period 14 8 ka mid holocene period 8 4 ka and late holocene period 4 0 ka the position of the s stf was determined by two methods 1 the location of the 10 degrees c isotherm and 2 the location of the highest sst gradients these new results suggest that the s stf was not continuous between east and west of new zealand during the glacial period steep sst gradients indicate that a strong s stf rapidly shifted south during the lgm and early deglaciation during the late deglacial and holocene periods the position of the s stf differs between the two methods with reduced sst gradients suggesting amore diffuse s stf in the solander trough at this time the glacial sst data suggest that the s stf shifted north to the west of new zealand while to the east there was a stronger sst gradient across the front this was possibly the result of an increased wind stress curl which could have been caused by stronger or more northerly southern hemisphere westerly winds shww or a merging of the shww split jet in this region

the application of radiocarbon age estimates to the dating of glacial sequences an example from the miami sublobe ohio u s a abstract despite the importance of dating glacial sequences little evidence has been available to highlight the stratigraphic issues associated with the interpretation of age analysis a compilation of radiocarbon data from the miami sublobe of the laurentide ice sheet provides a large enough data set more than 133 dates to identify at least two sources of error sample and unit variability and transportation problems analysis of different samples from the same stratigraphic level commonly differ by more than the reported one sigma error and 2 000 year differences do occur glacial entrainment and transportation emplace older organic material over younger in situ materials and this effect may also give age errors in the data set of up to 2 000 years at a minimum multiple radiocarbon ages from a sequence of units are necessary to assign a reliable age to events within a glacial sequence however representing multiple ages poses its own problems a graphical representation that combines the probability of each sample appears to be one solution

in situ cosmogenic 10be production rate at lago argentino patagonia implications for late glacial climate chronology abstract when calculated with the commonly accepted average northern hemisphere production rate 10 be dates of surface boulders on moraines in the lago argentino area of patagonia are younger than minimum limiting 14 c ages for the same landforms this disagreement could result from the lack of a regional 10 be production rate calibration site to assess this possibility we here present high precision measurements of 10 be in samples collected from surface boulders on the herminita and puerto bandera moraine complexes deposited alongside lago argentino on the eastern flank of the andes at 50 s in patagonia together with maximum and minimum limiting 14 c ages for the two moraine systems these measurements confine the local 10 be production rate to between 3 60 and 3 82 atoms g yr midpoint 3 71 0 11 atoms g yr when using a time dependent scaling method that incorporates a high resolution geomagnetic model this range includes upper and lower error bounds of acceptable production rates derived from both the herminita and the puerto bandera sites the upper limit of this range is more than 12 below the average northern hemisphere production rate as calculated using the same scaling method given in balco et al quat geochron 3 2008 174 195 other scaling models yield production rates with similarly large offsets from the balco et al 2008 rate on the other hand the range of acceptable production rate values determined from patagonia overlaps at 1 with and encompasses the production rate recently derived in macaulay valley in the southern alps of new zealand a putnam et al quat geochron 5 2010a 392 409 within uncertainties i e overlap at 1 sigma this patagonian production rate range also agrees with a recently determined production rate from low elevation sites in northeastern north america and northern norway when the macaulay production rate is used to calculate patagonian exposure dates 14 c and 10 be chronologies are mutually compatible for late glacial moraine systems both chronologies then indicate that outlet glaciers of the southern patagonian icefield achieved a late glacial maximum in the western reaches of lago argentino at 13 000 cal yr bp at the end of the antarctic cold reversal 14 500 12 900 cal yr bp outlet glaciers subsequently receded to near present day ice margins during the younger dryas stadial 12 900 11 700 cal yr bp this general retreat was interrupted about 12 200 cal yr bp when upsala glacier constructed an interlobate complex of moraine ridges on herminita peninsula mountain glaciers in patagonia and new zealand on both sides of the south pacific ocean exhibited a coherent pattern of late glacial ice margin fluctuations

an example of estimating rock mass deformation around an underground opening using numerical modeling abstract in rock engineering rock strength is regarded as an important rock mass parameter and it is widely estimated using the uniaxial compressive strength ucs test a ucs test in laboratory requires sampling and preparation of core samples which necessitates time consuming and expensive studies furthermore preparation of cores is almost impossible for a weak rock material taken from foliated laminated or thinly bedded rock masses of low rock quality designation rqd values 0 20 in this case determination of ucs by laboratory test may be impossible in compliance with isrm or astm standards to overcome this difficulty indirect tests such as point load index pli schmidt hammer sh rebound number tests are often employed to predict the ucs however indirect tests are likely to yield ucs values with large standard deviations depending on the geological origin of the rock mass the block punch index bpi has recently been developed to overcome the drawbacks of ucs and indirect tests and to minimize the errors arisen from the structural deficiencies and large standard deviations in this study determination of rock mass behavior in laminated foliated bornova melange yellowish brown flysch and grayish black flysch and well jointed yamanlar volcanics altindag formation where the second phase of the izmir metro tunnels was excavated is aimed the bpi ratings were directly used in rmr calculations and indirectly used to estimate the ucs values of rock materials then the obtained results were input into numerical models along with the rock mass strength ucs rm and deformation modulus of rock mass e rm the results obtained from the numerical models agreed with that obtained results from inner tunnel convergence and ground settlement measurements

the timing and nature of the last glacial cycle in new zealand abstract this paper constitutes a review of the last otiran glaciation in new zealand spanning marine isotope stages mis 4 2 we highlight the nature of glaciation which is characterised by exceptional sedimentation relatively mild maritime climatic conditions and the widespread presence of water associated with proglacial settings these conditions produce glacial systems characterised by extensive outwash fans and relatively small terminal moraines extensive recent geochronological work allows us to recognise at least eight glacial advances during the otiran these occurred at 65 3 25ka 47 5 3 ka 38 5 2 ka 31 5 3 ka 26 5 2 ka 20 5 2 ka 17 2 ka and 13 1 ka which we term the otira 1 to 8 advances respectively though the analytical uncertainty ranges for some of these advances overlap all are independently distinguished through moraine morphologic relationships and or stratigraphic relationships in outcrop major advances appear to be associated with climate influences such as periods of southern hemisphere insolation minima 65ka and 31 5 ka advances the last glacial maximum cooling lgm 20 5 ka and periods of antarctic cooling 13ka the timing of greatest glacial extent in the last glacial cycle is not simultaneous across new zealand the mis 4 advance was the greatest in the southern south island while the mis 3 2 advances 26 5 ka were greatest in the central south island in the northern south island and the north island mis 4 mis 3 2 and the last glacial maximum appear to be equivalent in extent we attribute these spatio temporal variations in the timing of maximum glaciation to precipitation changes related to a northward shift in the track of the westerlies

the last glacial maximum at 44 s documented by a 10be moraine chronology at lake ohau southern alps of new zealand abstract determining whether glaciers registered the classic last glacial maximum lgm 26 500 19 000 yrs ago coevally between the hemispheres can help to discriminate among hypothesized drivers of ice age climate here we present a record of glacier behavior from the southern alps of new zealand during the local lgm llgm we used 10 be surface exposure dating methods and detailed glacial geomorphologic mapping to produce a robust chronology of well preserved terminal moraines deposited during the llgm near lake ohau on central south island we then used a glaciological model to estimate a llgm glacier snowline and atmospheric temperature from the ohau glacier record seventy three 10 be surface exposure ages place culminations of terminal moraine construction and hence completions of glacier advances to positions outboard of present day lake ohau at 138 600 10 600 yrs 32 520 970 yrs ago 27 400 1300 yrs ago 22 510 660 yrs ago and 18 220 500 yrs ago recessional moraines document glacier recession into the lake ohau trough by 17 690 350 yrs ago exposure of an ice molded bedrock bench located inboard of the innermost llgm moraines by 17 380 510 yrs ago indicates that the ice tongue had receded about 40 of its overall length by that time comparing our chronology with distances of retreat suggests that the ohau glacier terminus receded at a mean net rate of about 77 m yr 1 and its surface lowered by 200 m between 17 690 and 17 380 yrs ago a long term continuation of ice retreat in the ohau glacier catchment is implied by moraine records at the head of irishman stream valley a tributary of the ohau glacier valley the irishman stream cirque glacier advanced to produce a set of lateglacial moraines at 13 000 500 yrs ago implying that the cirque glacier was less extensive prior to that advance we employed a glaciological model fit to these mapped and dated llgm moraines to derive snowline elevations and temperature parameters from the ohau glacier record the modeling experiments indicate that a snowline lowering of 920 50 m and temperature depression of 6 25 0 5 c below modern values allows for the ohau glacier to grow to an equilibrium position within the lgm moraine belt taken together with a glaciological simulation reported from the irishman stream valley snowlines and temperatures increased by at least 520 m and 3 6 c respectively between 18 000 and 13 000 yrs ago climate parameters derived from the ohau glacier reconstruction are similar to those derived from glacier records from patagonia to air temperature indicators from antarctica as well as to sea surface temperature and stratification signatures of the southern ocean we think that the best explanation for the observed southern llgm is that southern winter duration modulated southern ocean sea ice which in turn influenced southern ocean stratification and made the surface ocean cooler orbitally induced cooling of the southern ocean provides an explanation for the llgm in the southern alps having been coincident with the northern lgm we argue further that the global effect of north atlantic stadials led to disturbance of southern ocean stratification southward shifts of the subtropical front and retreat of southern alps glaciers collapse of southern ocean stratification during heinrich stadial 1 along with attendant sea surface warming triggered the onset of the last glacial termination in the southern alps of new zealand

drainage capture and discharge variations driven by glaciation in the southern alps new zealand sediment flux in proglacial fluvial settings is primarily controlled by discharge which usually varies predictably over a glacial interglacial cycle however glaciers can flow against the topographic gradient to cross drainage divides reshaping fluvial drainage networks and dramatically altering discharge in turn these variations in discharge will be recorded by proglacial stratigraphy glacial drainage capture often occurs in alpine environments where ice caps straddle range divides and more subtly where shallow drainage divides cross valley floors we investigate discharge variations resulting from glacial drainage capture over the past 40 k y for the adjacent ashburton rangitata and rakaia basins in the southern alps new zealand although glacial drainage capture has previously been inferred in the range our numerical glacier model provides the first quantitative demonstration that this process drives larger variations in discharge for a longer duration than those that occur due to climate change alone during the last glacial maximum the effective drainage area of the ashburton catchment increased to 160 of the interglacial value with drainage capture driving an increase in discharge exceeding that resulting from glacier recession glacial drainage capture is distinct from traditional base level driven drainage capture and is often unrecognized in proglacial deposits complicating interpretation of the sedimentary record of climate change

contributions and unrealized potential contributions of cosmogenic nuclide exposure dating to glacier chronology 1990 2010 abstract this paper reviews the application of cosmogenic nuclide exposure dating to glacier chronology exposure dating of glacial landforms has made an outsize impact on this field because the technique filled an obvious need that had already been recognized by glacial geologists by now hundreds of studies have used cosmogenic nuclide exposure dating to date glacial deposits and in fact it is rare to find a study of glacial geology or glacier chronology or any paleoclimate synthesis that makes use of such studies that does not involve exposure dating these developments have resulted in major contributions to glacier chronology and paleoclimate in particular i reconstructing antarctic ice sheet change ii establishing the chronology of late pleistocene and holocene glacier change in mountain regions where it was previously unknown iii establishing the broad chronological outlines of mountain glaciations prior to the last glacial maximum and iv gaining insight into subglacial erosional processes through the observation that many glaciated surfaces preserve cosmogenic nuclide inventories from long past ice free periods as well as the present one an important potential future contribution will be the application of the large data set of exposure dated glacier chronologies to better understand global and regional climate dynamics during lateglacial and holocene millennial scale climate changes however this contribution cannot be realized without significant progress in two areas i understanding and accounting for geologic processes that cause apparent exposure ages on glacial landforms to differ from the true age of the landform and ii minimizing systematic uncertainties in exposure ages that stem from cosmogenic nuclide production rate estimates and scaling schemes at present there exists an enormous data set of exposure ages on glacial deposits but these data cannot be used to their full potential in paleoclimate syntheses due to an inadequate understanding of geologic scatter and production rate uncertainties the intent of this paper is to highlight this situation and suggest some strategies for realizing this potential

high and low latitude climate control on the position of the southern peru chile current during the holocene 1 we reconstructed changes of temperature salinity and productivity within the southern peru chile current during the last 8000 years from a high resolution sediment core recovered at 41 s using alkenones isotope ratios of planktic foraminifera biogenic opal and organic carbon paleotemperatures and paleosalinities reached maximum values at 5500 years ago and thereafter declined to modern values whereas paleoproductivity continuously increased throughout the last 8000 years we ascribe these long term holocene trends primarily to latitudinal shifts of the antarctic circumpolar current acc the concurrence with shifts in the position of the southern westerlies points to a common response of atmospheric and oceanographic circulation patterns off southern chile millennial to centennial scale fluctuations of paleotemperatures and paleosalinities on the other hand lag displacements in the position of the southern westerlies but reveal a significant correlation to short term temperature changes in antarctica indicating a high latitude control of the acc at these timescales

support capacity estimation of a diversion tunnel in weak rock abstract this paper presents the results of the support capacity estimation for the diversion tunnel of the urus dam site in highly weathered tuff and weak zone tunneling in weak rock requires some special considerations since misjudgment in support design results in costly failures there are several ways of estimating rock support pressure and selecting support however all systems suffer from their characteristic limitations in achieving objectives thus it is more useful to use different methods for estimating support pressure and type of support the support pressure pi was established by three different methods these methods are the 1 empirical methods based on rock mass rating rmr and rock mass quality index q classification systems 2 ground support interaction analysis gsia and 3 numerical methods namely phase2 finite element fem program rock masses were characterized in terms of rsr rmr q system and gsi drill core samples were tested in the rock mechanics laboratory to determine physico mechanical properties rock mass strength was estimated by empirical methods finally the required support system is proposed and evaluated by different methods in the highly weathered tuff and weak zone of the diversion tunnel

antarctic timing of surface water changes off chile and patagonian ice sheet response marine sediments from the chilean continental margin are used to infer millennial scale changes in southeast pacific surface ocean water properties and patagonian ice sheet extent since the last glacial period our data show a clear antarctic timing of sea surface temperature changes which appear systematically linked to meridional displacements in sea ice westerly winds and the circumpolar current system proxy data for ice sheet changes show a similar pattern as oceanographic variations offshore but reveal a variable glacier response time of up to 1000 years which may explain some of the current discrepancies among terrestrial records in southern south america

recognition and hydrologic significance of passive margin updip sequences an example from eocene coastal plain deposits u s a abstract sequence stratigraphic interpretations are extended to a passive margin updip setting using sedimentological observations from cores and well to well correlations in eocene coastal plain strata of south carolina in the succession studied formation contacts tend to follow sequence boundaries even as lithologies vary within individual sequences sequence boundaries at the base of the congaree formation and near the top of the tinker formation formed during relative sea level fall associated with second order global cycles these boundaries can be recognized clearly in both downdip and updip areas of the passive margin three other sequence boundaries which occur at the base and top of the warley hill formation and within the tinker formation are interpreted as formed during relative sea level fall associated with third order global cycles hydrostratigraphic units in the strata studied conform to depositional patterns that were controlled by changes in sea level and sediment influx sand of the gordon aquifer comprises a thick aggradational succession deposited predominantly in the nearshore shelf environment as accommodation increased during relative rise in sea level because of high rates of sedimentation in the proximal setting aggradational stacking of nearshore sands may be common to other updip marine strata in accommodation dominated regimes the overlying gordon confining unit consists of marine shelf clay and carbonate sediment deposited in response to maximum transgression during subsequent relative sea level fall accumulation of shoreface deposits produced a progradational succession that is represented by the lower part of the upper three runs aquifer unlike formation contacts boundaries between the clastic aquifers and confining units do not follow the third order sequence boundaries because of lithologic variations within the sequences an increasing degree of breaching through the gordon confining unit which results in downward contaminant migration into the gordon aquifer occurs in the updip direction because of nearly continuous sand deposition near the base of the interval studied contaminants migrate locally through the crouch branch confining unit because of erosional breaches formed by scour during sea level lowstand in this example and in other strata deposited in an updip passive margin setting the extent to which confining units are breached at sequence boundaries decreases in the downdip direction resulting in better protection of the adjacent aquifer

sequence of events during the last deglaciation in southern ocean sediments and antarctic ice cores variation depends on the age model as 14 c determinations cannot be obtained for the time interval of 29 5 14 5 ka assuming a constant sedimentation rate for this interval our data suggest that sea ice and nutrient changes at about 19 ka b p lead the increase in atmospheric pco2 by approximately 2000 years our diatom based sea ice record is in phase with the sodium record of the vostok ice core which is related to sea ice cover and similarly leads the increase in atmospheric co2 if gas exchange played a major role in determining glacial to interglacial co2 variations then a delay mechanism of a few thousand years is needed to explain the observed sequence of events otherwise the main cause of atmospheric pco2 change must be sought elsewhere rather than in the southern ocean index terms 3344 meteorology and atmospheric dynamics paleoclimatology 4267 oceanography general paleoceanography 4845 oceanography biological and chemical nutrients and nutrient cycling 4870 oceanography biological and chemical stable isotopes 9325 information related to geographic region atlantic ocean keywords biogenic opal stable isotopes diatoms ird last glacial southern ocean

prediction of critical strains and critical support pressures for circular tunnel excavated in strain softening rock mass abstract the critical strain is a strain level at the tunnel periphery beyond which the instability and squeezing problems are likely to occur thereby it provides helpful guide to assess the tunnel stability among the current studies for predicting the critical strain the influence factors such as the required support pressure the strain softening behaviour of the rock mass and the in situ stress condition have not been comprehensively considered this paper aims to overcome the limitation by proposing an improved tunnel critical strain classification which consists of five typical critical strains and critical support pressures specifically two critical levels correspond to the occurrences of the plastic softening and residual zones of the strain softening rock mass at the tunnel periphery three tunnel strains of 2 5 5 and 10 represent the squeezing potentials of the rock mass the correlations between the input geological parameters and the geological strength index gsi are proposed on the basis of the existing empirical equations a numerical procedure is presented to solve the five critical strains and critical support pressures according to a large amount of the calculation result the response surfaces for the critical support pressures in relation to the gsi and in situ stress are obtained by the nonlinear regression method the obtained critical strains are compared with the critical strain levels and measured tunnel strains by the current studies the results indicate that the reason for the unexpected secure condition with the large deformation in the rock mass can be attributed to the non existence of the plastic residual zone as the rock mass strength improves the critical strain level reveals an unexpected growth which is correlative to the considerations of the in situ stress condition and the strain softening behaviour of the rock mass

millennial scale pulsebeat of glaciation in the southern alps of new zealand abstract we undertook geomorphological mapping in conjunction with 10be surface exposure dating in a previously unstudied sector of the left lateral moraine sequence of the ice age pukaki glacier in the southern alps of new zealand the mapping and dating approach enabled the identification of six distinct moraine belts that were formed during maxima of glacier extent during the last glaciation the chronology implies that ice recession occurred during northern hemisphere heinrich stadials while expansion occurred between heinrich stadials the ages of the moraine belts identified here are 44 000 1000 yrs 41 800 1100 yrs 36 450 940 yrs 26 730 740 yrs 20 030 460 yrs and 18 000 400 yrs this moraine chronology is consistent with previous dating results from other sectors of the pukaki moraine sequence except that the c 44 000 yr old moraine belt has not previously been detected elsewhere in the pukaki moraines collectively with previously published 10be chronologies from the pukaki glacier and the adjacent ohau glacier valley the results demonstrate that there were several millennial scale episodes of ice advance to full glacial extent and subsequent ice recession during marine isotope stages 3 and 2 this millennial scale pulsebeat of oscillations of the pukaki and ohau glaciers in sympathy with the north atlantic heinrich episodes is further emphasized by rapid ice recession in the southern alps early in the last glacial termination coeval with the onset of heinrich stadial 1 hs 1 in the northern hemisphere that this pattern is widespread in mid latitudes of the southern hemisphere is highlighted by similar chronologies of glacier variation for andean ice lobes in the chilean lake district of south america

climate sensitivity of a high precipitation glacier in new zealand the sensitivity of glaciers to climatic change is key information in assessing the response and sea level implications of projected future warming new zealand glaciers are important globally as an example of how maritime glaciers will contribute to sea level rise a spatially distributed energy balance model is applied to brewster glacier new zealand in order to calculate glacier mass balance run off and sensitivity to climate change the model successfully simulates four annual mass balance cycles close to half 52 of the energy available for melt on the glacier is supplied by turbulent heat fluxes with radiation less important except during the winter model sensitivity to temperature change is one of the largest reported on earth at 2 0 m w e a 1 8c 1 in contrast a 50 change in precipitation is required to offset the mass balance change resulting from a 18c temperature change meltwater run off sensitivity is also very high increasing 60 with a 18c warming the extreme sensitivity of mass balance to temperature change suggests that significant ice loss will occur with even moderate climate warming

deglacial temperature history of west antarctica the most recent glacial to interglacial transition constitutes a remarkable natural experiment for learning how earth s climate responds to various forcings including a rise in atmospheric co2 this transition has left a direct thermal remnant in the polar ice sheets where the exceptional purity and continual accumulation of ice permit analyses not possible in other settings for antarctica the deglacial warming has previously been constrained only by the water isotopic composition in ice cores without an absolute thermometric assessment of the isotopes sensitivity to temperature to overcome this limitation we measured temperatures in a deep borehole and analyzed them together with ice core data to reconstruct the surface temperature history of west antarctica the deglacial warming was formula see text c approximately two to three times the global average in agreement with theoretical expectations for antarctic amplification of planetary temperature changes consistent with evidence from glacier retreat in southern hemisphere mountain ranges the antarctic warming was mostly completed by 15 kybp several millennia earlier than in the northern hemisphere these results constrain the role of variable oceanic heat transport between hemispheres during deglaciation and quantitatively bound the direct influence of global climate forcings on antarctic temperature although climate models perform well on average in this context some recent syntheses of deglacial climate history have underestimated antarctic warming and the models with lowest sensitivity can be discounted

influence of the tropics and southern westerlies on glacial interhemispheric asymmetry latitudinal variations in the location of the southern westerly wind belt have been associated with millennial scale climate variations during the last glacial period a reconstruction of sea surface temperatures off the southern coast of australia suggests that these climate variations also drove changes in the location of the oceanic subtropical front

rapid changes of glacial climate simulated in a coupled climate model abrupt changes in climate termed dansgaard oeschger and heinrich events have punctuated the last glacial period approximately 100 10 kyr ago but not the holocene the past 10 kyr here we use an intermediate complexity climate model to investigate the stability of glacial climate and we find that only one mode of atlantic ocean circulation is stable a cold mode with deep water formation in the atlantic ocean south of iceland however a warm circulation mode similar to the present day atlantic ocean is only marginally unstable and temporary transitions to this warm mode can easily be triggered this leads to abrupt warm events in the model which share many characteristics of the observed dansgaard oeschger events for a large freshwater input such as a large release of icebergs the model s deep water formation is temporarily switched off causing no strong cooling in greenland but warming in antarctica as is observed for heinrich events our stability analysis provides an explanation why glacial climate is much more variable than holocene climate

sedimentology ichnology and paleoenvironments of the upper cretaceous wenonah and mt laurel formations new jersey abstract the wenonah and mt laurel formations of the new jersey coastal plain comprise a shallow subtidal coarsening upward regressive sequence that accumulated along a wave dominated coast in late cretaceous maestrichtian time the highly bioturbated muddy very fine to fine quartz sands of the wenonah formation were deposited mainly in the offshore zone of an inner shelf below storm wave base distinctive trace fossils include rosselia socialis and a planar form of zoophycos the mt laurel formation consists of two lithofacies in the northern new jersey coastal plain the formation is characterized by burrowed clean quartz sands that are thinly interbedded with muddy sand and mud characteristic trace fossils include ophiomorpha nodosa rosselia socialis two forms of skolithos and a delicate branching burrow deposition occurred mainly in the offshore shoreface transition zone between fair weather and storm wave base storm deposits include burrowed sands displaying trough cross stratification hummocky cross stratification lenticular and wavy ripple bedding and parallel lamination fair weather deposits consist of thoroughly bioturbated muddy sand and thin bedded mud at updip exposures shoreface deposits include trough cross strati ied burrowed fine to medium sands paleocurrents were bipolar with a predominant northwest onshore mode a massive sand lithofacies characterizes the mt laurel formation in the central and southern new jersey coastal plain and is characterized by highly bioturbated medium to coarse sand rare cross stratification indicates a polymodal paleocurrent pattern with predominantly northwest transport distinctive trace fossils include ophiomorpha nodosa and skolithos linearis this lithofacies accumulated mainly as shoals or bars in the transition and offshore zones of the inner shelf a shoreface ebb tidal delta facies was locally developed the marshalltown wenonah and mt laurel formations comprise a depositional sequence in the sense of haq et al 1987 that accumulated during a third order eustatic sea level cycle uza 4 4 the wenonah mt laurel regression occurred during a sea level high stand as sediments began to overflow estuaries created during the marshalltown transgression subsequent falling sea level intensified the regression and ultimately led to erosional truncation of the mt laurel sediments then eustatic rise in sea level during the late maestrichtian uza 4 5 led to ravinement during this ravinement event a fossiliferous and pebbly glauconitic quartz sand lithofacies was deposited as a transgressive lag in the transition and offshore zones of the inner shelf these transgressive sheet sand ediments comprise the lower part of the navesink formation the depositional model developed herein for the wenonah mt laurel regressive interval integrates both sedimentologic and ichnologic data this model is compared with the well known gallup and blackhawk cretaceous regressive sequences of the north american western interior it should be applicable in the evaluation of other regressive sequences in cretaceous strata of the u s atlantic coastal plain and western interior as well as epeiric sea cycles from other similar settings around the world

chironomid and pollen evidence for climate fluctuations during the last glacial termination in nw patagonia abstract we present chironomid and pollen records from the huelmo site 41 30 s nw patagonia to examine in detail the timing and structure of climate changes during the last glacial termination in the southern mid latitudes the chironomid record has the highest temporal and taxonomic resolution for this critical interval and constitutes the first account of midge faunas at the culmination of the last glacial maximum lgm for the region the chironomid record suggests cold and wet conditions during the lgm followed by deglacial warming between 17 6 and 16 8 cal kyr bp relatively warm conditions prevailed between 15 14 cal kyr bp followed by a reversal in trend with cooling pulses at 14 and 13 5 cal kyr bp and warming at the beginning of the holocene cool temperate conditions prevailed during the huelmo mascardi cold reversal hmcr which according to chironomid data exhibits a wet phase 13 5 12 8 cal kyr bp followed by a conspicuous drier phase 12 8 11 5 cal kyr bp the chironomid and pollen records from the huelmo site indicate step wise deglacial warming beginning at 17 6 cal kyr bp in agreement with other paleoclimate records from nw patagonia and isotopic signals from antarctic ice cores peak warmth during the last glacial termination was achieved by 14 5 cal kyr bp followed by a cooling trend that commenced during the antarctic cold reversal which later intensified and persisted during the hmcr 13 5 11 5 cal kyr bp we observe a shift toward drier conditions at 12 8 cal kyr bp superimposed upon the hmcr coeval with intense fire activity and vegetation disturbance during younger dryas time

modulation of the bipolar seesaw in the southeast pacific during termination 1 the termination of the last ice age termination 1 t1 is crucial for our understanding of global climate change and for the validation of climate models there are still a number of open questions regarding for example the exact timing and the mechanisms involved in the initiation of deglaciation and the subsequent interhemispheric pattern of the warming our study is based on a well dated and high resolution alkenone based sea surface temperature sst record from the se pacific off southern chile ocean drilling project site 1233 showing that deglacial warming at the northern margin of the antarctic circumpolar current system acc began shortly after 19 000 years bp 19 kyr bp the timing is largely consistent with antarctic ice core records but the initial warming in the se pacific is more abrupt suggesting a direct and immediate response to the slowdown of the atlantic thermohaline circulation through the bipolar seesaw mechanism this response requires a rapid transfer of the atlantic signal to the se pacific without involving the thermal inertia of the southern ocean that may contribute to the substantially more gradual deglacial temperature rise seen in antarctic ice cores a very plausible mechanism for this rapid transfer is a seesawinduced change of the coupled ocean atmosphere system of the acc and the southern westerly wind belt in addition modelling results suggest that insolation changes and the deglacial co2 rise induced a substantial sst increase at our site location but with a gradual warming structure the similarity of the two step rise in our proxy ssts and co2 over t1 strongly demands for a forcing mechanism influencing both temperature and co2 as ssts at our coring site are particularly sensitive to latitudinal shifts of the acc southern westerly wind belt system we conclude that such latitudinal shifts may substantially affect the upwelling of deepwater masses in the southern ocean and thus the release of co2 to the atmosphere as suggested by the conceptual model of toggweiler j r rusell j l carson s r 2006 midlatitude westerlies atmospheric co2 and climate change during ice ages

high frequency holocene glacier fluctuations in new zealand differ from the northern signature understanding the timings of interhemispheric climate changes during the holocene along with their causes remains a major problem of climate science here we present a high resolution 10be chronology of glacier fluctuations in new zealand s southern alps over the past 7000 years including at least five events during the last millennium the extents of glacier advances decreased from the middle to the late holocene in contrast with the northern hemisphere pattern several glacier advances occurred in new zealand during classic northern warm periods these findings point to the importance of regional driving and or amplifying mechanisms we suggest that atmospheric circulation changes in the southwest pacific were one important factor in forcing high frequency holocene glacier fluctuations in new zealand

the two step shape and timing of the last deglaciation in antarctica the two step character of the last deglaciation is well recognized in western europe in greenland and in the north atlantic for example in greenland a gradual temperature decrease started at the bolling b around 14 5 ky bp spanned through the allerod a and was followed by the cold younger dryas yd event which terminated abruptly around 11 5 ky bp recent results suggest that this ba yd sequence may have extended throughout all the northern hemisphere but the evidence of a late transition cooling is still poor for the southern hemisphere here we present a detailed isotopic record analyzed in a new ice core drilled at dome b in east antarctica that fully demonstrates the existence of an antarctic cold reversal acr these results suggest that the two step shape of the last deglaciation has a worldwide character but they also point to noticeable interhemispheric differences thus the coldest part of the acr which shows a temperature drop about three times weaker than that recorded during the yd in greenland may have preceded the yd antarctica did not experienced abrupt changes and the two warming periods started there before they started in greenland the links between southern and northern hemisphere climates throughout this period are discussed in the light of additional information derived from the antarctic dust record

southern ocean origin for the resumption of atlantic thermohaline circulation during deglaciation during the two most recent deglaciations the southern hemisphere warmed before greenland at the same time the northern atlantic ocean was exposed to meltwater discharge which is generally assumed to reduce the formation of north atlantic deep water yet during deglaciation the atlantic thermohaline circulation became more vigorous in the transition from a weak glacial to a strong interglacial mode here we use a three dimensional ocean circulation model to investigate the impact of southern ocean warming and the associated sea ice retreat on the atlantic thermohaline circulation we find that a gradual warming in the southern ocean during deglaciation induces an abrupt resumption of the interglacial mode of the thermohaline circulation triggered by increased mass transport into the atlantic ocean via the warm indian ocean and cold pacific ocean water route this effect prevails over the influence of meltwater discharge which would oppose a strengthening of the thermohaline circulation a southern ocean trigger for the transition into an interglacial mode of circulation provides a consistent picture of southern and northern hemispheric climate change at times of deglaciation in agreement with the available proxy records

late glacial mountain glacier culmination in arctic norway prior to the younger dryas abstract climate changes during the late glacial period lg 15 11 ka as recorded in greenland and antarctic ice cores show a bipolar pattern between 14 5 ka and 13 ka ago the northern latitudes experienced the bolling allerod ba warm period while southern records feature the antarctic cold reversal acr between 12 9 ka and 11 7 ka ago the north was under the younger dryas yd cold spell while southern latitude temperature rose in parallel to atmospheric co2 concentrations while the southern hemisphere pattern is well documented in mountain glacier moraine records from new zealand and patagonia in northern mid latitudes and the arctic the lg glacier culmination has been connected to the yd stadial apparently confirming the bipolar pattern we present a geomorphic map of mountain glaciers in arctic norway a cosmogenic nuclide chronology from 71 moraine boulders from the lg and the holocene and first order glacier modeling experiments the model and dating results show that the studied mountain glaciers are most sensitive to summer temperature change that their response to those changes is highly correlated to a wider region and that these mountain glaciers in arctic norway reached their maximum lg extent about 14 ka ago prior to the yd following considerable retreat through the first part of the yd glaciers re stabilized in the mid yd and showed slower oscillatory retreat through the latter part of the yd we compare this glacier pattern to updated earlier glacier records in the wider arctic and north atlantic region and propose a pattern of coherent glacier response to climate changes during this interval the lg results from arctic glaciers show consistency to the glacier record from new zealand and patagonia this first order interhemispheric coherency of lg mountain glacier fluctuations driven mainly by summer temperature would support the view that the bipolar seesaw was primarily a northern winter phenomenon during the lg period and the yd in particular more similar experiments need to be performed to further test this scenario

last glacial maximum climate in new zealand inferred from a modelled southern alps icefield abstract we present a simulation of the new zealand southern alps icefield at the last glacial maximum lgm c 30 000 20 000 calendar years ago ka in an attempt to constrain the climate of that period we use a 500 m resolution ice sheet model parameterised using empirical glaciological climatological and geological data specific to the model domain to simulate the entire southern alps icefield we find that an lgm cooling of at least 6 6 5 c is necessary to bring about valley glaciers that extend beyond the mountains however climate topography thresholds related to the elevation and hypsometry of individual catchments control the gradient of the rate of glacier expansion in the domain and in order to remain within geologically reconstructed lgm limits we find that the lgm cooling was most likely associated with a precipitation regime up to 25 drier than today wetter than present scenarios give rise to equilibrium line depressions and ice extents that are incompatible with empirical evidence these results perhaps indicate that either the westerly air masses affecting new zealand during the lgm were drier than today or that they were weaker or zonally displaced with respect to present

extracting a climate signal from 169 glacier records i constructed a temperature history for different parts of the world from 169 glacier length records using a first order theory of glacier dynamics i related changes in glacier length to changes in temperature the derived temperature histories are fully independent of proxy and instrumental data used in earlier reconstructions moderate global warming started in the middle of the 19th century the reconstructed warming in the first half of the 20th century is 0 5 kelvin this warming was notably coherent over the globe the warming signals from glaciers at low and high elevations appear to be very similar

a 70 kyr sea surface temperature record off southern chile ocean drilling program site 1233 1 we present the first high resolution alkenone derived sea surface temperature sst reconstruction in the southeast pacific ocean drilling program site 1233 covering the major part of the last glacial period and the holocene the record shows a clear millennial scale pattern that is very similar to climate fluctuations observed in antarctic ice cores suggesting that the southern hemisphere high latitude climate changes extended into the midlatitudes involving simultaneous changes in air temperatures over antarctica sea ice extent extension of the antarctic circumpolar current and westerly atmospheric circulation a comparison to other midlatitude surface ocean records suggests that this antarctic millennial scale pattern was probably a hemisphere wide phenomenon in addition we performed sst gradient reconstructions over the complete latitudinal range of the pacific eastern boundary current system for different time intervals during the last 70 kyr the main results suggest an equatorward displaced subtropical gyre circulation during marine isotope stages 2 and 4

storm features of siliciclastic shelf sedimentation in the mid cretaceous epeiric seaway of northern australia abstract late aptian to early cenomanian strata were deposited in a large epeiric seaway which covered much of the northern australian landmass during mid cretaceous time the seaway stretched from the carpentaria basin in the north to the eromanga basin in the south during this period siliciclastic sediments accumulated on a gently sloping epeiric shelf which formed the western margin of the carpentaria basin the shelf maintained a relatively similar configuration throughout the mid cretaceous with water depths rarely exceeding 50 m and the seafloor was apparently within the influence of storm waves over much of the area the shelf was storm and wave dominated and most early formed or fair weather sedimentary structures were destroyed or extensively modified during episodic storms storm features include hummocky cross stratification shelly lags erosional conglomeratic lags gutter casts lenticular micro hummocky sand beds megaripples characteristic low diversity and opportunistic ichnofacies various styles of wave ripple lamination and poorly preserved event beds most storm influenced units are preserved as coarsening and shallowing upwards facies successions which aggraded during high relative sea level and prograded during falling relative sea level some of these successions were subsequently eroded during further cyclic fluctuations of relative sea level

scaling time integrated in situ cosmogenic nuclide production rates using a continuous geomagnetic model abstract spatial and temporal variations in earth s magnetic field affect the corresponding time integrated distribution of in situ cosmogenic nuclide cn production rates these effects can be quantified by the effective vertical cutoff rigidity r c a measure of the energy required for primary cosmic rays to penetrate the geomagnetic field and interact with the atmosphere at a given location recent cn production rate scaling models are based on atmospheric cosmic ray measurements parameterized using r c estimates derived from detailed modern geomagnetic field representations which include both dipole and non dipole field contributions however published methods for quantifying time integrated geomagnetic effects on cn production rate scaling rely on various geocentric dipolar approximations to r c driven by separate records of paleomagnetic pole position and paleointensity therefore applying dipolar paleomagnetic records spanning millennial time scales which explicitly ignore past non dipole effects to scaling models derived using modern geomagnetic field representations may lead to systematic errors in any calculated results a recently published continuous geomagnetic model covering the last 7 kyr cals7k 2 m korte and c g constable continuous geomagnetic field models for the past 7 millennia 2 cals7k 2005 geochem geophys geosyst 6 q02h16 doi 10 1029 2004gc000801 may allow reduction of such errors by bridging the gap between detailed modern geomagnetic and simplified paleomagnetic models we have developed a new model framework describing temporal and spatial variation in r c for 0 7 ka and earlier based on cals7k 2 which explicitly accounts for non dipole field effects while attempting to mitigate systematic scaling biases scaling factors derived using the new r c framework predict significant longitudinal variability in time integrated cn production while predictions using dipolar geomagnetic approximations do not one can test these predictions using in situ cosmogenic 14 c in situ 14 c in quartz due to its short half life 5 73 kyr 14 c attains secular equilibrium between production and decay after approximately 25 kyr of exposure at which point its measured concentration is only a function of its integrated average production rate initial in situ 14 c results from samples at secular equilibrium from 38 n and 3 5 km in tibet and eastern california are consistent with the longitudinal variability predicted by the new framework

the spatial extent and dynamics of the antarctic cold reversal the last deglaciation was interrupted by the antarctic cold reversal proxy records and climate modelling suggest that a redistribution of oceanic and atmospheric heat caused changes in temperature and hydrology across the southern hemisphere

sedimentology and depositional environments of middle eocene terrigenous carbonate strata southeastern atlantic coastal plain usa abstract basin margin sediments of middle eocene age in the savannah river site area consist of five terrigenous carbonate lithofacies quartz sand calcareous quartz sand sandy carbonate muddy carbonate and a transitional lithofacies that ranges from sandy muddy carbonate to calcareous mud the middle eocene sediment package which includes calcareous parts of the upper congaree warley hill and santee formations dips southeast at 4 7 m km and thickens from 2 m at its updip edge to 95 m downdip the presence of glauconite and a diverse faunal assemblage in all lithofacies suggests deposition in clear well oxygenated open marine waters of normal salinity on the inner to middle shelf with periods of marginal marine nearshore and deltaic influence coarse grained terrigenous sand and calcareous sand deposited in higher energy nearshore environments occur near the updip limit fine grained terrigenous mud calcareous mud and sandy and muddy carbonate are located downdip and accumulated in quieter water conditions on the inner and middle shelf the transition from terrigenous to carbonate sediment occurs near the updip limit in a narrow zone less than 5 km wide three depositional sequences which contain transgressive and highstand system tracts are recognized within the middle eocene calcareous interval one is assigned to the upper congaree formation ta 3 5 3 6 cycles the main control on areal distribution hill formation ta3 4 cycle and one to the santee formation ta 3 5 3 6 cycles the main control on areal distribution of facies was depositional environment which was controlled primarily by sea level eustasy and the amount rate and locus of terrigenous influx in updip areas however sediment distribution and thickness were also influenced by middle eocene growth faulting diagenetic pathways vary with facies type but generally include 1 marine phreatic boring of skeletal fragments by algae and fungi grain micritization and radially fibrous cementation and 2 freshwater phreatic inversion of high mg calcite to low mg calcite dissolution of aragonitic allochems formation of moldic porosity precipitation of syntaxial calcite overgrowths on echinoderms formation of calcite spar and isopachous calcite cement neomorphism of micrite to microspar and pseudospar precipitation of opal ct lepispheres replacement of mollusk shells by chalcedony and precipitation of zeolites within secondary moldic pores quartz rich facies have high interparticle porosity and excellent permeability mud rich facies have low to moderate porosity and permeability owing to the isolation of moldic and vug pores

glacier advance in southern middle latitudes during the antarctic cold reversal the geographic extent of cooling associated with the antarctic cold reversal is unclear dating of glacial moraines in new zealand suggests that the cooling extended into the southern mid latitudes possibly as a result of the northward migration of the southern subtropical front

an evaluation of 14c age relationships between co occurring foraminifera alkenones and total organic carbon in continental margin sediments 1 radiocarbon age relationships between co occurring planktic foraminifera alkenones and total organic carbon in sediments from the continental margins of southern chile northwest africa and the south china sea were compared with published results from the namibian margin age relationships between the sediment components are site specific and relatively constant over time similar to the namibian slope where alkenones have been reported to be 1000 4500 years older than co occurring foraminifera alkenones were significantly similar to 1000 years older than co occurring foraminifera in the chilean margin sediments in contrast alkenones and foraminifera were of similar age within 2 sigma error or better in the nw african and south china sea sediments total organic matter and alkenone ages were similar off namibia age difference toc alkenones 200 700 years chile 100 450 years and nw africa 360 770 years suggesting minor contributions of preaged terrigenous material in the south china sea total organic carbon is significantly 2000 3000 years older owing to greater inputs of preaged terrigenous material age offsets between alkenones and planktic foraminifera are attributed to lateral advection of organic matter physical characteristics of the depositional setting such as seafloor morphology shelf width and sediment composition may control the age of co occurring sediment components in particular offsets between alkenones and foraminifera appear to be greatest in deposition centers in morphologic depressions aging of organic matter is promoted by transport age offsets are correlated with organic richness suggesting that formation of organic aggregates is a key process

vertical sequence and lateral transitions in the facies of a barred nearshore environment abstract nine tube cores 7 cm in diameter and up to 150 cm long from a nearshore crescentic bar in kouchibouguac bay new brunswick canada reveal the vertical sequence and lateral transitions of facies previously identified only in shallow box cores the facies are a inner shelf shoreface transition bioturbated fine sands and silts with remnant primary structures b seaward slope planar lamination in medium to fine sands dipping gently seaward and composite bed sets of planar to ripple cross lamination in fine sand chevron lamination is rare c bar crest low angle planar lamination dipping both landward and seaward and medium scale trough cross lamination in medium to coarse sands d landward slope planar lamination dipping landward with small scale la dward dipping trough cross lamination occasionally small to medium scale trough cross lamination is found with seaward dips e trough massively bedded lags of coarse gravelly sands with abundant shell fragments contrast with isolated very thin units of massive silt and units of well sorted sands the latter display subhorizontal planar lamination and small to medium scale trough cross lamination polymodal dips indicate bed form migration landward alongshore and offshore vertical sequences and lateral transitions seaward of the bar crest suggest that three wedge shaped units inner shelf shoreface transition seaward slope bar crest interdigitate in an offlap onlap sequence to landward the trough and landward slope facies interfinger complexly while the crest facies forms a simple onlap over landward slope facies total reworking of sediments within the bar trough system is expected every 5 to 6 years and long term preservation is limited to the inner shelf shoreface transition seaward slope and trough facies

tropical cooling at the last glacial maximum and extratropical ocean ventilation1 1 the ncar csm is used to simulate the climate at last glacial maximum the csm simulates a tropical sst cooling of 2 1 c it is shown that about half of this tropical cooling is associated with the upper ocean circulation especially the ventilation of thermocline and intermediate waters from the mid high latitude south pacific

a 2 d numerical model of snow ice energy balance and ice flow for paleoclimatic interpretation of glacial geomorphic features abstract standard methods of interpreting the paleoclimates recorded in alpine glacial geomorphic features rely on estimates of paleoglacier shape commonly assume that relationships between mass balance gradient and equilibrium line altitude of modern glaciers apply equally well to glaciers of in many cases dramatically different climates and do not account for the varying influence of topography on glacial extent while those methods may be adequate for many studies there are an increasing number of areas in which that level of analysis does not match the level of detail of the glacial chronologies being developed as an alternative we present a physically based 2 d glacier model that can be used to determine steady state glacier shapes and distributions for a wide range of climatic conditions the model requires only a modest amount of data beyond that which would be required for simpler methods and includes a relatively accurate representation of the effects of topography on the largest component of the surface energy balance shortwave radiation it calculates 2 d in the horizontal plane distribution of snow accumulation using a surface mass and energy balance approach and calculates the resultant glacier shapes with a 2 d flow model in addition to offering a potentially more accurate reconstruction of paleoclimatic conditions the model provides a means of performing detailed sensitivity analysis establishing relationships between similar deposits in basins of different shape and aspect and of predicting glacier shape terminus position in areas not yet explored

evolution of a classic sand ridge field maryland sector north american inner shelf the ridge and swale topography of the middle atlantic bight is best developed on the delaware maryland inner shelf here sand ridges can be seen in all stages of formation several aspects of the ridge field are pertinent to the problem of ridge genesis the first is ridge morphology there is a systematic morphologic change from shoreface ridges through nearshore ridges to offshore ridges which reflects the changing hydraulic regime as successively more seaward ridges are examined maximum side slope decreases the ratio of maximum seaward slope to maximum landward slope decreases and the cross sectional area increases these changes in ridge morphology with depth and distance from shore appear to be equivalent to the morphologic changes experienced by a single ridge during the course of the holocene transgression a second aspect is the change in bottom sediment characteristics that accompanies these large scale morphologic changes megaripples sand waves and mud lenses appear in the troughs between nearshore and offshore ridges these changes indicate that the storm flows which maintain ridges are less frequently experienced in the deeper sector and that the role of high frequency wave surge becomes less important relative to the role of the mean flow component in shaping the sea floor a third aspect is the systematic relationship of grain size to topography grain size is 90 out of phase with topography so that the coarsest sand lies between the axis of the landward trough and the ridge crest while the finest sand lies between the ridge crest and the axis of the seaward trough this relationship is characteristic of large scale bedforms finally flow was measured and transport calculated on the same ridge during a one month period november 1976 threshold was exceeded only during storm events mean transport was southerly and a little seaward with respect to both the ridge crest and the shoreline these flow measurements are in conformity with the pattern of smaller bedforms a 43 year time series of bathymetric change for this ridge reveals a systematic pattern of landward flank erosion seaward flank deposition and seaward crest migration sand ridges are considered the consequence of constructive feedback between an initial topography and the resulting distribution of bottom shear stress the relationship between grain size and topography supports this model but does not account directly for the oblique angle of the ridge with respect to the coastline this feature may be due to a more rapid alongshore migration rate of the inshore edge of the ridge than the offshore edge and the relationship between this migration rate and the rate of shoreface retreat

does the bipolar seesaw extend to the terrestrial southern mid latitudes abstract high precision comparison of greenland and antarctic ice cores suggesting a pervasive antiphased temperature relationship between the polar hemispheres during the last glaciation lends strong support to the bipolar seesaw model epica 2006 the extent to which reorganisation of ocean heat transport during abrupt climate change events affected the southern mid latitudes remains unclear however owing to a paucity of well dated records with robust climate proxies variability between some records and varying interpretations of their significance here we present temperature reconstructions for three key pollen records recognised by the nz intimate nz i group which along with the preliminary nz i climate event stratigraphy alloway et al 2007 and published marine records are compared with polar ice core records for the interval 30 10 cal ka we focus on key events within the context of dansgard oeschger cycles 4 1 and the antarctic cold reversal younger dryas intervals the new zealand records are broadly consistent with an extended bipolar seesaw whereby the oceanic southern mid latitudes are warmed at times of moc weakening or cessation in the north atlantic and vice versa variability between records indicate that other factors must be involved however and nor do these records refute alternative models that predict an antiphased inter hemispheric pattern nevertheless an extended bipolar model may explain an early onset of lgm conditions in new zealand and elsewhere in the southern hemisphere at a time when interstadials gi3 and gi4 kept greenland warm similar inter hemispheric dynamics have been invoked to explain an earlier termination of the lgm in antarctica than in greenland wolff et al 2009 which is also evident in the new zealand records a prominent mid lgm interstadial complex observed in several new zealand records connected by tephrochronology may represent another antiphased event although stronger chronological control is needed to support this assertion by comparison the variability evident between new zealand lateglacial records cannot be explained simply by chronological imprecision and there may be latitudinal controls on the extent to which the antarctic pattern is registered as has been suggested from other records from the southern mid high latitudes consolidation of these patterns is needed from more precise climate reconstructions at sites spread across latitudinal gradients in both the marine and terrestrial realms

facies architecture and sequentiality of nearshore and shelf sandbodies haystack mountains formation wyoming usa the haystack mountains formation campanian mesaverde group us western interior basin wyoming contains a series of shallow marine sandbodies extending tens of kilometres out from a basin margin the study succession around 200 m thick is composed of eight major sandstone tongues bolten ranch o brien spring seminoe 1 2 3 4 hatfield 1 and 2 members each partially encased within marine shale intervals the formation is sequential at several scales at the largest scale the whole succession presents an aggradational to basinward stepping stacking pattern of the sandstone tongues at a lower level each tongue member is characterized internally by two different types of lithosome the first represents shoreface progradation with hummocky cross strata passing up to swaley and trough cross stratified sandstones this lithosome is erosively truncated at its top in most cases and has a general sheet like geometry along strike whereas down dip it displays a series of sharp bounded clinothems the latter sometimes indicate a downward as well as a basinward shift through time as suggested by the occurrence of coarser and or shallower facies at a lower level in the shoreface profile the second type of lithosome is sheet or wedge like and sharply overlies the shoreface deposits the lithosome consists of laterally widespread units of planar tabular to trough cross bedded medium sandstones passing laterally in a dip direction into bioturbated sandstones the lower part of this lithosome is progradational becoming retrogradational into the overlying shales the facies within the cross bedded lithosome suggest a tidally dominated delta front to estuarine depositional setting the two types of lithosome are not related genetically the erosion surface separating the two lithosomes is a sequence boundary separating forced regressive relative sea level fall shoreface deposits from lowstand to transgressive early relative sea level rise cross bedded deposits the uppermost part of the cross stratified lithosome shows a landward stepping of component parasequences and is abruptly blanketed by open marine shales the most widespread cross bedded lithosomes are apparently best developed in the lowermost members of the haystack mountains formation i e in the aggradational part of the large scale progradational succession in the uppermost highly progradational sandstone tongues the shoaling upward shoreface lithosome dominates whereas the cross bedded lithosome occurs in narrow lensoid belts or is absent the middle portion of the succession shows intermediate characteristics the vertical variation in geometry thickness and progradational extent of successive cross bedded lithosomes results from greater confinement of the incised nearshore systems both in space landward direction and in time from the aggradation to the progradation architecture the latter is a consequence of a decreasing rate of accommodation creation through time

reconstruction of paleo wave conditions during the late pleistocene from marine terrace deposits monterey bay california the santa cruz coastal terrace fringes much of the northern monterey bay region california it consists mainly of a regressive sequence of high energy barred nearshore marine sediments deposited during the last sangamonian highstand of sea level this sequence can be sub divided into several depth dependent facies on the basis of paleo current data and vertical sequence of sedimentary structures these include a lower shoreface facies deposited in 10 16 m water depth an upper shoreface facies including both a storm dominated assemblage and a surf zone assemblage deposited in 0 10 m water depth and a foreshore facies deposited in the swash zone up to 3 5 m above high tide the magnitudes of the storm events responsible for depositing these sediments were estimated by calculating paleo wave heights using a variety of criteria e g critical threshold equations breaker depths berm heights in addition the climate and paleogeography during the deposition of these sediments were essentially the same as today allowing the use of present day wave statistics to estimate the frequency of these storm events the largest storms formed offshore flowing currents e g rip wind forced and possibly storm surge ebb currents that resulted in the deposition of approximately 30 of the sediments seaward of the surf zone however the magnitude and frequency of these events are unknown the remaining 70 of the sediment beyond the surf zone was deposited in response to smaller storm waves which were on the average at least 1 6 m high such waves presently occur no more than 15 of the time sediments deposited during fairweather conditions i e the remaining 85 of the time have a low preservation potential and are generally not preserved in this facies in contrast surf zone sediments were deposited by a variety of processes associated with waves whose maximum offshore heights were probably 2 2 m such waves presently occur up to 92 of the time sediments within the swash zone were deposited by waves up to 3 m high the largest of which presently occur approximately 2 of the time most of the sediments were deposited by storms of intermediate magnitude and frequency different facies however appear to preferentially record events of different recurrence intervals in particular surf zone sediments were deposited under relatively small storm and post storm conditions whereas sediments deposited farther offshore record increasingly larger less frequent storm events relatively rare events e g the 100 or 1000 yr events do not appear to have significantly affected sedimentation in these nearshore environments

extensive recession of cordillera darwin glaciers in southernmost south america during heinrich stadial 1 abstract the geographic expression and phasing of events during the last termination are important for isolating mechanisms that caused earth to emerge from the last ice age heinrich stadial 1 hs1 14 600 18 000 yr bp is a key because of the central role that its far field effects had on the last termination in the southern hemisphere here we present new data from cordillera darwin that show rapid glacier recession in southern south america during hs1 this retreat was coeval with ice recession elsewhere in south america and new zealand with increased upwelling in the southern ocean with warming of ssts offshore of chile and with a rise in atmospheric co2 together these data indicate a coherent and rapid response to the effects of hs1 in the middle and high latitudes of the southern hemisphere

eocene biostratigraphy of south carolina and its relationship to gulf coastal plain zonations and global changes of coastal onlap an assimilation of mega invertebrate assemblages in south carolina with gulf coast biozones allows for the subdivision of the middle and late eocene into four regional zonations that can be compared with proposed global sequences controlled by eustatic changes of sea level the middle eocene can be divided in ascending stratigraphic order into the cubitostrea perplicata zone c lisbonensis zone and c sellaeformis zone the late eocene is represented by the crassatella alta chlamys cawcawensis zone these zones are separated by type 1 or type 2 unconformities that bracket global sequence boundaries unconformity types after vail and todd 1981 the following sequences are proposed for the middle and upper eocene te2 1 cubitostrea perplicata zone followed by a type 2 unconformity te2 2 c lisbonensis zone followed by a type 2 unconformity te2 3 c sellaeformis zone followed by a type 1 unconformity and te3 crassatella alta chlamys cawcawensis zone followed by a type 2 unconformity although not recognized in the downdip areas of south carolina the te3 sequence can be further subdivided into a te3 1 sequence and te3 2 sequence separated by a type 2 unconformity this regional break lies at the gosport sand lower moodys branch formation upper moodys branch formation contact in the gulf coastal plain and at the base of the tivola tonque in georgia

temperature change is the major driver of late glacial and holocene glacier fluctuations in new zealand advance and retreat of temperate glaciers is largely controlled by changes in temperature and precipitation but the relative importance of these drivers is debated numerical modeling of a new zealand glacier reveals that temperature is the dominant control on glacier length we find that a glacial advance dated to ca 13 000 yr b p requires a cooling event of 3 4 c this mid latitude southern hemisphere cooling is similar in magnitude to the antarctic cold reversal in the vostok ice core record and likely to be a response to the same climate signal

a new greenland ice core chronology for the last glacial termination 1 we present a new common stratigraphic timescale for the north greenland ice core project ngrip and grip ice cores the timescale covers the period 7 9 14 8 kyr before present and includes the bolling allerod younger dryas and early holocene periods we use a combination of new and previously published data the most prominent being new high resolution continuous flow analysis cfa impurity records from the ngrip ice core several investigators have identified and counted annual layers using a multiparameter approach and the maximum counting error is estimated to be up to 2 in the holocene part and about 3 for the older parts these counting error estimates reflect the number of annual layers that were hard to interpret but not a possible bias in the set of rules used for annual layer identification as the grip and ngrip ice cores are not optimal for annual layer counting in the middle and late holocene the timescale is tied to a prominent volcanic event inside the 8 2 kyr cold event recently dated in the dye 3 ice core to 8236 years before a d 2000 b2k with a maximum counting error of 47 years the new timescale dates the younger dryas preboreal transition to 11 703 b2k which is 100 150 years older than according to the present grip and ngrip timescales the age of the transition matches the gisp2 timescale within a few years but viewed over the entire 7 9 14 8 kyr section there are significant differences between the new timescale and the gisp2 timescale the transition from the glacial into the bolling interstadial is dated to 14 692 b2k the presented timescale is a part of a new greenland ice core chronology common to the dye 3 grip and ngrip ice cores named the greenland ice core chronology 2005 gicc05 the annual layer thicknesses are observed to be log normally distributed with good approximation and compared to the early holocene the mean accumulation rates in the younger dryas and bolling periods are found to be 47 2 and 88 2 respectively

late quaternary glacier sensitivity to temperature and precipitation distribution in the southern alps of new zealand glaciers respond to climate variations and leave geomorphic evidence that represents an important terrestrial paleoclimate record however the accuracy of paleoclimate reconstructions from glacial geology is limited by the challenge of representing mountain meteorology in numerical models precipitation is usually treated in a simple manner and yet represents difficult to characterize variables such as amount distribution and phase furthermore precipitation distributions during a glacial probably differed from present day interglacial patterns we applied two models to investigate glacier sensitivity to temperature and precipitation in the eastern southern alps of new zealand a 2 d model was used to quantify variations in the length of the reconstructed glaciers resulting from plausible precipitation distributions compared to variations in length resulting from change in mean annual air temperature and precipitation amount a 1 d model was used to quantify variations in length resulting from interannual climate variability assuming that present day interglacial values represent precipitation distributions during the last glacial a range of plausible present day precipitation distributions resulted in uncertainty in the last glacial maximum length of the pukaki glacier of 17 1 km 24 and the rakaia glacier of 9 3 km 25 corresponding to a 0 5 c difference in temperature smaller changes in glacier length resulted from a 50 decrease in precipitation amount from present day values 14 and 18 and from a 50 increase in precipitation amount 5 and 9 our results demonstrate that precipitation distribution can produce considerable variation in simulated glacier extents and that reconstructions of paleoglaciers should include this uncertainty

deglacial palaeoclimate at puerto del hambre subantarctic patagonia chile the primary objective of this study is to further substantiate multistep climatic forcing of late glacial vegetation in southern south america a secondary objective is to establish the age of deglaciation in estrecho de magallanes bahia inutil pollen assemblages at 2 cm intervals in a core of the mire at puerto del hambre 53 36 21 s 70 55 53 w provide the basis for reconstructing the vegetation and a detailed account of palaeoclimate in subantarctic patagonia chronology over the 262 cm length of core is regulated by 20 ams radiocarbon dates between 14 455 and 10 089 14c yr bp of 13 pollen assemblage zones the earliest representing the oldest dryas chronozone 14 455 13 000 14c yr bp records impoverished steppe with decreasing frequencies and loss of southern beech nothofagus successive 100 yr long episodes of grass herbs and of heath empetrum ericaceae before 14 000 14c yr bp infer deglacial successional communities under a climate of increased continentality prior to the establishment of grass dominated steppe the bolling allerod 13 000 11 000 14c yr bp is characterised by mesic grassland under moderating climate that with abrupt change to heath dominance after 12 000 14c yr bp was warmer and not as humid at the time of the younger dryas 11 000 10 000 14c yr bp grass steppe expanded with a return of colder more humid climate later with gradual warming communities were invaded by southern beech the puerto del hambre record parallels multistep deglacial palaeoclimatic sequences reported elsewhere in the southern andes and at taylor dome in antarctica deglaciation of estrecho de magallanes bahia inutil is dated close to 14 455 14c yr bp invalidating earlier dates of between 15 800 and 16 590 14c yr bp copyright 2000 john wiley sons ltd

preservation and grain size trends of holocene wave dominated facies successions in eastern japan implications for high resolution sequence stratigraphic analysis vertical grain size trends provide significant information for the sequence stratigraphic analysis of siliciclastic wave dominated facies successions this paper discusses the relationships between the preservation timing and the grain size trends of holocene wave dom inated successions in two contrasting coastal plains the kujukuri and sendai using high resolution ams 14 c dating depositional facies and grain size modal grain size is proposed as a good criterion for eval uating qualitative changes of depositional depth the kujukuri and sendai successions are both fining upward to coarsening upward wave dominated successions that have developed upon ravinement surfaces the fining upward part of the kujukuri succession formed in regressive deposits during a highstand period whereas that of the sendai formed during transgression a difference in the timing of the generation of upward fining is due to the varying preservation potential of transgressive shoreface deposits on the ravi nement surface in the sendai area the potential was much higher than in the kujukuri area because the sendai ravinement surface had re ceived greater sediment supply from the adjacent rivers during trans gression a differing rate of tectonic uplift between the areas was not critical to the preservation potential because of the short time scale the successions show bimodal grain size distributions in the basal parts and unimodal distributions elsewhere the bimodality is consid ered to be the result of mixing of a coarse transgressive lag with finer sediment derived from external sources the finer mode forms a con sistent trend with unimodal grain sizes in overlying deposits the trend is of a simple upward coarsening in the kujukuri and an upward fining to coarsening in the sendai showing distinctive correlation with chang es of depositional depth thus the vertical trend of the modal grain size and not mean or median is best for evaluating changes of de positional depth in ancient wave dominated facies successions

onset of deglacial warming in west antarctica driven by local orbital forcing an annually resolved ice core record from west antarctica indicates that warming driven by local insolation resulting from sea ice decline began in that region about 2 000 years before warming in east antarctica reconciling two alternative explanations for deglacial warming in the southern hemisphere

evaluation of lateglacial temperatures in the southern alps of new zealand based on glacier modelling at irishman stream ben ohau range abstract climate proxy records from the middle to high latitude southern hemisphere indicate that a lateglacial 15 000 11 500 years ago climate reversal approximately coeval with the antarctic cold reversal acr interrupted a warming trend during deglaciation in new zealand some palaeoclimate proxy records indicate a cool episode during the acr ca 14 500 12 500 years ago while others do not express a significant change in climate recently published moraine maps and ages present an opportunity to improve the palaeoclimate interpretation through numerical modelling of glaciers we use a coupled energy balance and ice flow model to quantify palaeoclimate from past glacier extent constrained by mapped and dated moraines in the headwaters of irishman stream a high elevation catchment in the southern alps first a suite of steady state model runs is used to identify the temperature and precipitation forcing required to fit the modelled glacier to well dated lateglacial moraine crests second time dependent glacier simulations forced by a nearby proxy temperature record derived from chironomids are used to assess the fit with the glacial geomorphic record steady state experiments using an optimal parameter set demonstrate that the conditions under which the 13 000 year old moraine formed were 2 3 3 2 c colder than present with the range in temperature corresponding to a 20 variance in precipitation relative to the present day this reconstructed climate change relative to the present day corresponds to an equilibrium line altitude of ca 2000 40 m above sea level asl which is ca 400 m lower than present time dependent simulations of glacier length produce ice advance to within 100 m of the 13 000 year old terminal moraine indicating that the chironomid based temperature forcing and moraine record provide consistent information about past climate our results together with other climate proxy reconstructions from pollen records and marine sediment cores support the notion that temperatures during the acr in new zealand were 2 3 c cooler than today

a high resolution absolute dated late pleistocene monsoon record from hulu cave china oxygen isotope records of five stalagmites from hulu cave near nanjing bear a remarkable resemblance to oxygen isotope records from greenland ice cores suggesting that east asian monsoon intensity changed in concert with greenland temperature between 11 000 and 75 000 years before the present yr b p between 11 000 and 30 000 yr b p the timing of changes in the monsoon as established with 230th dates generally agrees with the timing of temperature changes from the greenland ice sheet project two gisp2 core which supports gisp2 s chronology in this interval our record links north atlantic climate with the meridional transport of heat and moisture from the warmest part of the ocean where the summer east asian monsoon originates

glacier retreat in new zealand during the younger dryas stadial the younger dryas a period of sudden cooling in the northern hemisphere about 12 900 years ago is perhaps the best known example of abrupt climate change but the global extent of the younger dryas is a topic of intense debate particularly in the record of glacial behaviour in new zealand a new reconstruction of the growth and retreat patterns of glaciers in the southern alps in new zealand at the time of the younger dryas supports the suggestion that temperature reductions in the north caused warming and glacial retreat in the southern hemisphere through a series of climate feedbacks the younger dryas during which northern hemisphere temperatures cooled drastically in just a few years is perhaps the best known example of abrupt climate change but its global extent is under debate particularly in the record of glacial behaviour in new zealand these authors present evidence for glacial retreat in new zealand during the younger dryas supporting the hypothesis that northern hemisphere climate changes caused southern hemisphere warming through a series of climate feedbacks millennial scale cold reversals in the high latitudes of both hemispheres interrupted the last transition from full glacial to interglacial climate conditions the presence of the younger dryas stadial 12 9 to 11 7 kyr ago is established throughout much of the northern hemisphere but the global timing nature and extent of the event are not well established evidence in mid to low latitudes of the southern hemisphere in particular has remained perplexing1 2 3 4 5 6 the debate has in part focused on the behaviour of mountain glaciers in new zealand where previous research has found equivocal evidence for the precise timing of increased or reduced ice extent1 2 3 the interhemispheric behaviour of the climate system during the younger dryas thus remains an open question fundamentally limiting our ability to formulate realistic models of global climate dynamics for this time period here we show that new zealand s glaciers retreated after 13 kyr bp at the onset of the younger dryas and in general over the subsequent 1 5 kyr period our evidence is based on detailed landform mapping a high precision 10be chronology7 and reconstruction of former ice extents and snow lines from well preserved cirque moraines our late glacial glacier chronology matches climatic trends in antarctica southern ocean behaviour and variations in atmospheric co2 the evidence points to a distinct warming of the southern mid latitude atmosphere during the younger dryas and a close coupling between new zealand s cryosphere and southern high latitude climate these findings support the hypothesis that extensive winter sea ice and curtailed meridional ocean overturning in the north atlantic led to a strong interhemispheric thermal gradient8 during late glacial times in turn leading to increased upwelling and co2 release from the southern ocean9 thereby triggering southern hemisphere warming during the northern younger dryas

radiocarbon chronology of the last glacial maximum and its termination in northwestern patagonia abstract we examine the timing and magnitude of the last glacial maximum lgm and the last glacial termination lgt in northwestern patagonia situated in the middle latitudes of south america our data indicate that the main phase of the lgt began with abrupt warm pulses at 17 800 and 17 100 cal yrs bp accompanied by rapid establishment of evergreen temperate rainforests and extensive deglaciation of the andes within 1000 years this response shows that south american middle latitude temperatures had approached average interglacial values by 16 800 cal yrs bp the temperature rise in northwestern patagonia coincides with the beginning of major warming and glacier recession in the southern alps of new zealand at southern mid latitudes on the opposite side of the pacific ocean from this correspondence the warming that began at 17 800 cal yrs bp appears to have been widespread in middle latitudes of the southern hemisphere accounting for at least 75 of the total temperature recovery from the lgm to the holocene moreover this warming pulse is coeval with the first half of the heinrich stadial 1 hs1 in the north atlantic region hs1 featured a decline of north atlantic meridional overturning circulation a southward shift of the westerly wind belt in both hemispheres and of the intertropical convergence zone as well as a weakening of the asian monsoon along with the initiating trigger identifying the mechanisms whereby these opposing climate signals in the two polar hemispheres interacted whether through an oceanic or an atmospheric bipolar seesaw or both lies at the heart of understanding the lgt

expression of the bipolar see saw in antarctic climate records during the last deglaciation ice core records of climate from greenland and antarctica show asynchronous temperature variations on millennial timescales during the last glacial period 1 the warming during the transition from glacial to interglacial conditions was markedly different between the hemispheres a pattern attributed to the thermal bipolar see saw 2 however a record from the ross sea sector of east antarctica has been suggested to be synchronous with northern hemisphere climate change 3 here we present a temperature record from the talos dome ice core also located in the ross sea sector we compare our record with ice core analyses from greenland based on methane synchronization 4 and find clearly asynchronous temperature changes during the deglaciation we also find distinct differences in antarctic records pointing to differences in the climate evolution of the indo pacific and atlantic sectors of antarctica in the atlantic sector we find that the rate of warming slowed between 16 000 and 14 500 years ago parallel with the deceleration of the rise in atmospheric carbon dioxide concentrations and with a slight cooling over greenland in addition our chronology supports the hypothesis that the cooling of the antarctic cold reversal is synchronous with the bolling allerod warming in the northern hemisphere 14 700 years ago 5 the period from about 8 to 25kyr before present bp includes the climate transition from the last glacial to the holocene as documented from polar ice cores and other climate archives the pattern of climate changes throughout this transition is different between antarctica and the surrounding southern ocean and the northern hemisphere the steady antarctic deglacial warming reaches a first maximum antarctic isotopic maximum aim1 ref 1 followedbyaninterruptiontowardscoolerconditionsduring the antarctic cold reversal acr conversely greenland records show two rapid warming phases at the onset of the dansgaard oeschger 1 do1 event bllingaller dinterstadial b a andthe

late glacial and holocene glacier fluctuations in north island new zealand abstract geological records of past glacier extent can yield important constraints on the timing and magnitude of pre historic climate change here we present a cosmogenic 3he moraine chronology from mt ruapehu in central north island new zealand that records fluctuations of new zealand s northernmost glaciers over the last 14 000 years in the mangaehuehu glacier catchment exposure ages and geomorphic observations at our most distal moraine site relative to the current glacier margin show that glacial retreat during the last glacial termination was interrupted by one or more readvances between 14 and 11 ka further up valley moraine boulders deposited at 4 5 ka indicate that glaciers were more extensive during the mid holocene than at any later time the youngest exposure ages in our study 150 450 years constrain the formation of moraines situated within 500 m from the present day mangaehuehu glacier terminus these ages are in agreement with historic sources that show the glacier close to these moraine limits approximately 100 years ago overall our data show that glaciers on mt ruapehu retreated c 3 km since 14 ka in response to a net rise in the local equlibrium line altitude of c 400 m the magnitude of post industrial snowline rise and glacier retreat on mt ruapehu is also consistent with instrumental temperature data that record approximately 0 9 c of warming during the 20th century

efficacy of genetic algorithm to investigate small scale aquitard leakage the movement of water from a shallow aquifer to a semiconfined aquifer through a localized area of leakage in an aquitard designated as an aquitard window is an area of concern in certain gulf coastal plain aquifer settings locating these windows or areas of leakage has been historically arduous the purpose of this study was to evaluate the use of a genetic algorithm ga technique as an inverse technique for locating highly probable areas of leakage based upon aquifer head data near the suspected area of leakage the ga technique has previously been tested on synthetic data alone and this research offers insight into the capabilities of the technique with actual field data from a site with a known aquitard window research sites with historical and ongoing data collection efforts are rare and offer the best opportunity for robust evaluation of new methodologies based upon the ga technique the steady state accretion flux to the memphis aquifer at the shelby farms study site was determined to be 12 346 m day with a standard deviation of 821 m day and compared well with the range from 510 to 9 911 m day previously determined for the site

evidence for slow late glacial ice retreat in the upper rangitata valley south island new zealand abstract a suite of cosmogenic radionuclide ages taken from boulders on lateral and latero terminal moraines in the rangitata valley eastern south island new zealand demonstrates that relatively thick ice occupied valley reaches inland of the rangitata gorge until c 21 ka thereafter ice began to thin and by c 17 ka it had retreated 33 km up valley of the rangitata gorge to the butler brabazon downs a structurally created basin in the upper rangitata valley despite its magnitude this retreat represents a minor ice volume reduction from 21 ka to 17 ka and numerous lateral moraines preserved suggest a relatively gradual retreat over that 4 ka period in contrast to records from adjacent valleys there is no evidence for an ice collapse at c 18 ka we argue that the rangitata record constitutes a more direct record of glacial response to deglacial climate than other records where glacial dynamics were influenced by proglacial lake development such as the rakaia valley to the north and the major valleys in the mackenzie basin to the south west our data supports the concept of a gradual warming during the early deglaciation in the south island new zealand