schmidt hammer exposure age dating shd performed on periglacial and related landforms in opplendskedalen geirangerfjellet norway implications for mid and late holocene climate variability schmidt hammer exposure age dating shd was applied to a variety of boulder dominated periglacial landforms in an attempt to establish a local mid late holocene chronology for the geirangerfjelle

a minimum sample size required from schmidt hammer measurements the schmidt hammer is a useful tool applied by geomorphologists to measure rock strength in field conditions the essence of field application is to obtain a sufficiently large dataset of individual rebound values which yields a meaningful numerical value of mean strength although there is general agreement that a certain minimum sample size is required to proceed with the statistics the choice of size i e number of individual impacts was usually intuitive and arbitrary in this paper we show a simple statistical method based on the two sample student s t test to objectively estimate the minimum number of rebound measurements we present the results as 1 the mean and median solutions each providing a single estimate value and 2 the empirical probability distribution of such estimates based on many field samples schmidt hammer data for 14 lithologies 13 81 samples for each with each sample consisting of 40 individual readings have been evaluated assuming different significance levels the principal recommendations are 1 the recommended minimum sample size for weak and moderately strong rock is 25 2 a sample size of 15 is sufficient for sandstones and shales 3 strong and coarse rocks require 30 readings at a site 4 the minimum sample size may be reduced by one third if the context of research allows for higher significance level for test statistics interpretations based on less than 10 readings from a site should definitely be avoided copyright 2009 john wiley sons ltd

climate change signature of small scale parasequences from lateglacial holocene transgressive deposits of the arno valley fill abstract despite recent report of short term cyclicity from lateglacial holocene deposits of several coastal plains worldwide no precise documentation of the key factors controlling cyclic facies architecture has been made available by previous work detailed sedimentological analysis of a continuously cored borehole around the town of pisa in western tuscany provides evidence for the occurrence of three high frequency transgressive regressive cycles within the post last glacial maximum lgm transgressive succession 13 8 cal kyr bp of the arno incised valley fill these cycles which are bounded by lateral equivalents of marine flooding surfaces are 8 12 m thick and correspond to small scale parasequences micropalaeontological foraminifers and ostracods investigations based upon differentiation of eight microfossil associations allow to refine the stratigraphic framework emphasizing subtle changes in palaeosalinity across parasequence boundaries diagnostic changes in vegetation patterns driven by opposite climate conditions enable precise documentation of parasequence development as a function of climate change pollen spectra invariably show expansions of broad leaved forests at parasequence boundaries suggesting that rapid shifts to warmer climate conditions accompanied episodes of rapid sea level rise in contrast stillstand phases saw the development of cold temperate communities upper parts of parasequences suggesting transition to temporary colder climate conditions reconstruction of parasequence architecture on the basis of adjacent stratigraphic data combined with palaeoclimate characterization and radiometric dating enable identification within the transgressive arno valley body of three major regressive pulsations that are tentatively correlated with the most important cooling events of the post lgm period the sedimentary response to these short term phases of climatic cooling is clearly documented by episodes of widespread coastal plain and bay head delta progradation leading to partial estuary infilling and temporary establishment of continental environments in the proximal and central sectors of the valley

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

precise determination of the open ocean 234u 238u composition uranium has a long residence time in the open oceans and therefore its salinity normalized u concentration and 234u 238u activity ratio expressed herein as 234u the deviation from secular equilibrium are assumed to be uniform the marine 234u 238u activity ratio is currently in radioactive disequilibrium and shows a 15 excess of 234u with respect to the secular equilibrium value due to continuous input from riverine sources knowledge of the marine 234u and how it has evolved through the quaternary is important for validating age accuracy in the u series dating of marine carbonates which is increasingly relied upon for providing a chronological basis in paleoclimate research however accurate and precise measurements of 234u are technically difficult thus existing compilations of the open ocean 234u value vary by up to 10 and the assumed uniformity in the oceanic 234u remains to be confirmed using mc icpms techniques and a suite of multiple faraday cups instead of the typical configurations based on a combined faraday cup multiplier array a long term reproducibility of better than 0 3 2 is achieved for 234u measurements applying these very high precision techniques to open ocean seawater samples an average 234u of 146 8 0 1 2 m n 19 is obtained these high precision seawater measurements yield an external reproducibility of better than 0 4 2 and show that the open oceans have a uniform 234u on the sub level these new data constrain the vertical mixing time of the open oceans to less than 1000 years

late pleistocene coastal evolution of san giovanni di sinis west sardinia western mediterranean abstract the upper pleistocene succession of coastal deposits outcropping at san giovanni di sinis west sardinia has been studied since the 1960s however the absence of consistent radiometric ages has allowed the production of competing stratigraphic subdivisions of these deposits with different isotopic stage ois mis attributions the succession is composed of sandy to gravelly shallow marine coastal aeolian and alluvial fan plain deposits facies analysis and log correlations show the presence of three unconformities t1 t2 t3 always overlain by shallow marine deposits cutting through the substrate alluvial fan or aeolian sediments we have collected three samples for optically stimulated luminescence osl dating at the top of each shallow marine deposit the succession is composed of four unconformity bounded units u1 u2 u3 u4 and the new osl dates indicate the presence of three different sea level highstands the first unit u1 which is composed of shallow marine to aeolian deposits and overlies transgressive surface t1 is related to a marine transgression during ois 7 186 13 ky unit 2 is composed of continental deposits and formed during ois 6 unit 3 represents ois 5 and overlies a transgressive surface t2 more precisely subunit u3a is related to ois 5e 120 10 ky eu tyrrhenian or eemian sensu strictu and is characterized by shallow marine to aeolian deposits developed during both transgressive and highstand phases the following bay deposits of subunit 3b are associated with ois 5c 100 5 ky and record a second transgressive event t3 and highstand phase occurred during the neo tyrrhenian the succession of san giovanni di sinis ends with continental deposits of unit 4 associated to a sea level fall that took place at the beginning of the last glacial phase ois 4

influence of secular variation of the geomagnetic field on production rates of in situ produced cosmogenic nuclides abstract scaling factors are presented that allow a full description of the cosmic ray flux modulation during secular variation of the geomagnetic field these scaling factors are analogous to those determined in a similar work dunai t j earth planet sci lett 2000 176 157 169 that were accurate for field strengths equivalent to present day field strength but cannot accommodate field strength variations strategies to derive the relevant geomagnetic field parameters are discussed and are tested with existing production rate calibrations for 3 he a production rate of 103 4 2 atoms g olivine yr sea level and for zero cutoff rigidity was derived from calibration sites from hawaii western usa and canary islands covering the time range of 2 281 kyr

the little ice age maximum in the southern alps new zealand preliminary results at mueller glacier lichenometric dating studies using the yellow green rhizocarpon subgenus at mueller glacier in the region of mt cook southern alps new zealand reveal a little ice age maximum about ad 1725 1730 differences from previous studies are shown to result from different methods especially the type of mathematical functions used for calculating the lichenometric dating curves previous work also used variable sample sizes distal moraine slopes and to some extent different fixed points schmidt hammer measurements enable the differentiation of little ice age from pre little ice age frontal moraines in the outer glacier foreland and confirm the status of the little ice age as a separate glacier advance among several advances during the holocene

six decades of glacier mass balance observations a review of the worldwide monitoring network glacier mass balance is the direct and undelayed response to atmospheric conditions and hence is among the essential variables required for climate system monitoring it has been recognized as the largest non steric contributor to the present rise in sea level six decades of annual mass balance data have been compiled and made easily available by the world glacier monitoring service and its predecessor organizations in total there have been 3480 annual mass balance measurements reported from 228 glaciers around the globe however the present dataset is strongly biased towards the northern hemisphere and europe and there are only 30 reference glaciers that have uninterrupted series going back to 1976 the available data from the six decades indicate a strong ice loss as early as the 1940s and 1950s followed by a moderate mass loss until the end of the 1970s and a subsequent acceleration that has lasted until now culminating in a mean overall ice loss of over 20 m w e for the period 1946 2006 in view of the discrepancy between the relevance of glacier mass balance data and the shortcomings of the available dataset it is strongly recommended to 1 continue the long term measurements 2 resume interrupted long term data series 3 replace vanishing glaciers by early starting replacement observations 4 extend the monitoring network to strategically important regions 5 validate calibrate and accordingly flag field measurements with geodetic methods and 6 make systematic use of remote sensing and geo informatics for assessment of the representativeness of the available data series for their entire mountain range and for the extrapolation to regions without in situ observations and 7 make all these data and related meta information available

schmidt hammer exposure age dating shd of snow avalanche impact ramparts in southern norway approaches results and implications for landform age dynamics and development schmidt hammer exposure age dating shd was applied to the problem of dating the diachronous surfaces of five distal river bank boulder ramparts deposited by snow avalanches plunging into the jostedola and sprongdola rivers in the jostedalsbreen region of southern norway approaches to local high precision linear age calibration which controlled in different ways for boulder roundness were developed the mean age shdmean and the maximum age shdmax of surface boulders were estimated for whole ramparts crests and distal fringes interpretation was further assisted by reference to r value distributions shdmean ages with 95 confidence intervals ranged from 520 270 years to 5375 965 years whereas shdmax ages expected to be exceeded by 5 of surface boulders ranged from 675 to 9065 years shd ages from the jostedola ramparts tended to be older than those associated with the sprongdola rampart crests were younger than the respective distal fringes and use of relatively rounded boulders yielded more consistent shd ages than angular boulders the shdmean ages indicate differences in recent levels of snow avalanche activity between ramparts and provide insights into rampart dynamics as boulders are deposited on rampart crests and in smaller numbers on the distal fringes shdmax ages provide minimum age estimates of rampart age i e the time elapsed since the ramparts began to form and suggest that at least some of the ramparts have been developing since the early holocene copyright 2015 john wiley sons ltd

simulation of snow shielding corrections for cosmogenic nuclide surface exposure studies abstract snow cover reduces cosmogenic nuclide production rates in bedrock corrections for snow cover can be more than 10 in mountainous mid latitude regions where many glacial chronologies have been constructed using cosmogenic nuclide surface dating of landforms most published snow corrections use historic climate data of limited duration that are not likely to reflect adequately the full range of snow conditions over the time of exposure we present a model for describing the impact of snow burial on long term exposure histories of landforms the model applies an energy balance approach to snowpack evolution and incorporates both historic and long term climate proxy data attenuation of cosmogenic fast neutrons is modeled alternatively as a simple exponential decrease with increased shielding or as a thin surface layer with constant production followed by an exponential decrease with increasing depth the choice of attenuation model has little effect on the modeled results for the cairngorms but will have a more significant effect in regions characterized by thinner less dense snowpacks spatial variability in snow cover is modeled as a function of elevation only ignoring local variability in snow accumulation as a result of slope aspect wind redistribution and local topography thus model results reveal general spatial and temporal trends in snow shielding effects rather than site specific corrections applications to data from the cairngorm mountains of scotland show that the constant plus exponential cpe production rate depth profile reduces but does not eliminate snow shielding effects under present day conditions snow at 900 m in the cairngorm mountains reduces average production rates by 6 using the cpe profile and 9 with the exponential profile ep long term climate simulations from 15 5 ka through today produce larger snow shielding effects mainly because they predict an increased proportion of precipitation as snowfall during the younger dryas at 900 m this long term simulation reduces average cosmogenic isotope production rates by 12 cpe and 14 ep these results indicate that snow shielding corrections based on historic climate records may be a potential source of systematic error in midlatitude mountainous regions

234u 238u ratios and230th ages for hateruma atoll corals implications for coral diagenesis and seawater234u 238u ratios published results for corals that are more than ca 50 ka old from for example barbados and vanuata often yield initial 234u 238u activity ratios that are significantly greater than 1 144 0 004 the value for modern seawater this study reports results for corals from hateruma atoll japan and investigates the effects of diagenesis on the initial 234u 238u ratios of the corals hateruma consists of over 95 reef material of less than 500 ka in age because groundwaters associated with recent carbonates tend not to have elevated 234u 238u ratios the scope for increasing the 234u 238u ratios of hateruma corals through groundwater interaction should be minimal the corals examined range from those which show no petrographic or x ray evidence for diagenetic alteration and are pristine to those containing secondary cements of either aragonite or high or low mg calcite these various phases have been mechanically separated and analysed in agreement with previous assertions the analyses of these separates demonstrates that the presence of calcite should be a cause for rejection of coral samples it is also shown that aragonite cement can form later than coral death and may bias estimates of age and initial 234u 238u ratios of the six pristine corals three have anomalous 230th 238u ratios requiring u loss and or230th addition the remaining fifteen of the eighteen total analyses reported here yield ages from 1 6 ka to 260 ka no evidence for an increase in 234u 238u ratios in past seawater from this period has been found the best estimates for 234u 238u ratios are close to the current seawater value

investigation of late holocene moraines in the western southern alps new zealand applying schmidt hammer exposure age dating chronological studies applying schmidt hammer exposure age dating shd were performed on six glacier forelands in the western part of the southern alps new zealand although lithological heterogeneity prevented a regional age calibration curve to be established local age calibration curves for la perouse glacier and strauchon glacier could be derived they show similar linear equations and trends slopes and enabled a preliminary assessment of the representativeness of individual 10be terrestrial cosmogenic nuclide dating tcnd ages obtained from the other forelands no mid and early holocene advance periods were detected clusters of moraine ages date around 2800 1850 1450 and 1100 900 years ago followed by the little ice age commencing c 500 years ago there is no good agreement with earlier radiocarbon based studies and recently published tcnd chronologies as it will be outlined this partly could be the result of different approaches to the palaeoclimatic interpretation of the dated samples

age determination of glacially transported boulders in ireland and scotland using schmidt hammer exposure age dating shd and terrestrial cosmogenic nuclide tcn exposure age dating schmidt hammer exposure age dating shd was applied at 15 sites with glacially transported granite boulders in parts of northern and western ireland and southwest scotland that had been exposed by retreat of the last british irish ice sheet biis or younger dryas yd ice masses seven of these surfaces had previously been dated using terrestrial cosmogenic nuclide tcn exposure age dating application of the granite calibration equation of tomkins et al 2018c indicated a close correspondence between the shd ages and the tcn ages within 1 or 2 uncertainties these findings demonstrate that shd ages can be of comparable accuracy precision and reliability to tcn ages and are a strong argument for the more extensive use of shd in some quaternary dating projects however surface ages obtained by both shd and tcn dating should not be accepted uncritically they must be assessed in relation to the wider geological geomorphological and geochronological evidence evaluation of eight shd ages for which corresponding tcn ages are not available indicate that most are consistent with current theory and field evidence but some anomalous age estimates occur

middle to late pleistocene coastal deposits of alghero northwest sardinia italy chronology and evolution the shallow marine to coastal deposits of alghero have been dated using the optically stimulated luminescence osl method and studied to define the palaeoenvironmental evolution of coastal areas in northwest sardinia dating coupled with sedimentological and stratigraphical analyses allowed the subdivision of the succession in four unconformity bounded units u2 u3a u3b u4 unit u2 of penultimate glacial stage mis 6 ca 150 ka is composed of dune deposits formed intermittently along rocky coastal areas under strong wind conditions subunit u3a is composed of cliff bounded gravelly dominated pocket beach deposits commonly highly fossiliferous and is assigned to the interglacial mis 5e ca 125 ka subunit u3b is characterized by sandy beach to coastal systems of the isotopic sub stage mis 5c ca 100 ka the unconformity between u3b and u4 marks the initiation of last glacial regression mis 5a 4 ca 77 ka during which shelf areas were exposed and small incised valleys developed along the valley flanks colluvial or sheetflood sediments were deposited and in the central part thick reddish paleosols formed valleys were eventually filled by thick aeolian dune deposits mis 4 3 indicating persistent inland sand transport around alghero coastal carbonate rich dunes preferentially formed and migrated inland during lowstand and falling stages when the climate is relatively cold vegetation is quite open winds are fairly strong and sediment supply from exposed shelf areas is high

stratigraphy facies analysis and chronology of quaternary deposits at capo s marco sinis peninsula west sardinia italy abstract capo s marco is the southernmost termination of the sinis peninsula in the northwestern border of the oristano gulf western sardinia italy in the area there are some of the most controversial and debated quaternary deposits of sardinia consisting of beach aeolian and slope sediments whose chronological attribution changed according to different authors and in different times by the same authors these discrepancies have not been solved by new radiometric dates as radiocarbon and optically stimulated luminescence osl methods provided ages that are significantly different during recent investigations at capo s marco beach notches filled with bioclastic sands gravels and boulders were discovered up to an elevation of 4 5 m which is the highest elevation of the known beach notches these sediments rest on aeolian deposits and form a marine terrace in two sites in some places these sediments also include small colonies of the coral cladocora caespitosa in living position that have been recently dated by u th at 70 4 ka and attributed to the end of mis 5 here we report new u series analyses of two samples of c caespitosa collected on the uppermost part of the sequence the u th ages of 153 0 8 and 149 0 6 ka would correspond to mis 6 but the high values for the initial 234u 177 and 179 compared to the modern seawater value 147 point to an open system addition of 234u and or 230th the corrected ages using the open system model of thomson et al are 141 6 2 and 132 2 ka however these deposits and the beach notches are not buried under aeolian or colluvial sediments as are almost all the tyrrhenian marine deposits found in sardinia they also rest on aeolian sediments which at san giovanni di sinis were dated to mis4 or late mis2 by osl and radiocarbon dating of buried organic palaeosols respectively accordingly the stratigraphic evidence would suggest their attribution to the holocene although this contrasts with the holocene sea level models available and the u th dating results

onset of neoglaciation in the southern hemisphere a review of evidence documenting an early neoglacial mid holocene advance of mountain glaciers in south america and new zealand reveals that of 16 glaciers for which radiocarbon age control exists only two have associated dates that may approximate the culmination of an advance advances of the remaining glaciers are controlled only by minimum or maximum limiting ages additional dates for several new zealand glaciers are based on weathering rind measurements having large potential errors twelve of the glaciers now terminate or have terminated in lakes or in tidewater and are subject to instabilities associated with calving termini an extensive debris cover in the ablation zone of nearly half of the glaciers makes their moraine succession potentially suspect as a record of detailed climatic variation the two glaciers with seemingly reliable age control are located in valleys where large rock avalanches could affect glacier mass balance and lead to random advances or where rock avalanche deposits might easily be mistaken for moraines and tills the early neoglacial interval has been defined primarily based on this set of data the ages taken at face value suggest that the early neoglacial advance culminated between ca 5400 and 4900 cal yr ago ca 4600 4400 14c yr bp this chronology however should remain provisional until improved age control is obtained for a large population of glaciers based on closely bracketing radiocarbon dates and or an adequate number of cosmogenic isotope ages data from calving glaciers and those subject to rock avalanche activity should be avoided or assessed critically copyright 2000 john wiley sons ltd

chronostratigraphic confirmation of mis 5 age of a baymouth bar at is arenas cagliari italy in 2005 the national geological survey of italy released the new sheet 557 cagliari 1 50 000 scale a coastal barrier marine formation at is arenas cagliari sardinia italy containing strombus bubonius was reassigned a holocene age in contradiction with extensive literature published over the past century indicating an mis 5 5 age in 2007 spurred by this controversy a short note was published in il quaternario demonstrating the stratigraphic difficulties in attributing the age of this formation to the holocene later another paper signed by numerous italian geologists was published in il quaternario criticizing the holocene attribution the tectonic consequences of assigning a holocene age to these deposits are of great significance as their elevation could only be explained by strong uplift over the past few thousand years such a tectonic setting would imply a radical change in the recent geodynamic history of sardinia which is considered to be among the most stable areas of the mediterranean basin this paper provides further geochronological data for a mis 5 age for the deposits at is arenas electron spin resonance esr analyses were performed on 4 fossil shells sampled along the fossil baymouth bar the results established an mis 5 age the amino acid racemization aar and u series data that first determined a correlation with the last interglacial tyrrhenian age of this ancient shoreline is reviewed with additional documentation provided by the fossil marker s bubonius

tyrrhenian coastal deposits from sardinia italy a petrographic record of high sea levels and shifting climate belts during the last interglacial isotopic substage 5e abstract detailed petrographic and sedimentological analysis of tyrrhenian coastal deposits from four sites in sardinia provides new data about climate and sea level changes during the early part of the last interglacial isotopic substage 5e and shows that facies analysis is not only useful for the identification of ancient depositional environments but also represents a powerful tool for evaluating past climatic conditions and sea level forcing mechanisms two shallowing upward sequences sensu ward w c brady m j 1979 strandline sedimentation of carbonate grainstones upper pleistocene yucatan peninsula mexico am assoc pet geol bull 63 362 369 commonly separated by an erosion surface and displaying complex geometric relationships occur above modern sea level at several locations along the shorelines of sardinia these sequences include upper shoreface to backshore deposits and were formed during separate sea level highstands attributed to isotopic substage 5e our recent revision of these deposits indicates that each sequence presents distinctive petrographic characteristics the older succession essentially contains mixed calcarenites rich in quartz grains and lithic fragments whereas the younger sediments are dominated by carbonate bioclasts such as red algae coral and mollusk fragments both units apparently accumulated in a similar depositional setting but during different climatic regimes the petrography of the lower unit reflects a temperate humid period characterized by increased weathering and continental erosion whereas the composition of the upper one suggests a dryer and possibly warmer climate favoring active carbonate production the disparity in petrographic composition between sequences probably records the migration of atmospheric circulation cells i e a shift of climate belts before and after the 128 ka insolation maximum our climatic data are coherent with the calculated insolation curves for isotopic substage 5e and thus support the milankovitch hypothesis for the origin of pleistocene climates in contrast our sedimentological data clearly show the occurrence of two distinctive highstands of sea level during this time period which does not agree with the hypothesis it follows that the relation between orbitally induced insolation variations climate and sea level is not necessarily straightforward

rates of holocene chemical weathering little ice age glacial erosion and implications for schmidt hammer dating at a glacier foreland boundary fabergstolsbreen southern norway average rates of holocene chemical weathering and little ice age glacial erosion of bedrock are estimated across the glacier foreland boundary of an outlet glacier of the jostedalsbreen ice cap southern norway estimates are derived from two types of evidence 1 the heights of quartz veins above adjacent surfaces of granitic or granodioritic gneiss and 2 schmidt hammer r values of rock hardness average and maximum rates of surface lowering of gneiss surfaces by chemical weathering are 1 63 and 3 61 mm ka respectively whereas many quartz veins exhibit negligible weathering after c 9700 years little ice age glacial erosion rates are at least two orders of magnitude greater than the chemical weathering rates except in a narrow marginal zone inside but close to the little ice age limit where patches of weathered surface survive bedrock surfaces outside and well inside the little ice age glacier foreland boundary are shown to have potential for improved calibrated age dating using r val

geochronology for some key sites along the coast of sardinia italy recent stratigraphic surveys and facies analyses have questioned long held interpretations of the development and furthermore the age of quaternary sediments along the coast of sardinia the matter of debate is whether the investigated sediments were deposited during the late wurmian and holocene or during marine isotope stage mis 5 and older stages optically stimulated luminescence standard blue optically stimulated luminescence osl post infrared ir pulsed blue osl and post ir infrared stimulated luminescence irsl dating was applied to shallow marine and aeolian deposits as well as radiocarbon dating to bulk organic material in palaeosols radiocarbon dates suggest sedimentation during the late wurmian and holocene whilst the luminescence results for both quartz and potassium feldspar indicate a depositional age for most of the investigated sites prior to and during mis 5 from a geochronological point of view the luminescence ages are considered reliable because they passed all quality tests furthermore there is good agreement of two dosimeters with different bleaching and luminescence properties the radiocarbon ages might suffer from underestimation due to some contamination with young carbon which however cannot be large enough to yield such young ages

improved moraine age interpretations through explicit matching of geomorphic process models to cosmogenic nuclide measurements from single landforms abstract the statistical distributions of cosmogenic nuclide measurements from moraine boulders contain previously unused information on moraine ages and they help determine whether moraine degradation or inheritance is more important on individual moraines here we present a method for extracting this information by fitting geomorphic process models to observed exposure ages from single moraines we also apply this method to 94 10 be apparent exposure ages from 11 moraines reported in four published studies our models represent 10 be accumulation in boulders that are exhumed over time by slope processes moraine degradation and the delivery of boulders with preexisting 10 be inventories to moraines inheritance for now we neglect boulder erosion and snow cover which are likely second order processes given a highly scattered data set we establish which model yields the better fit to the data and estimate the age of the moraine from the better model fit the process represented by the better fitting model is probably responsible for most of the scatter among the apparent ages our methods should help resolve controversies in exposure dating we reexamine the conclusions from two published studies based on our model fits

behaviour of new zealand glaciers and atmospheric circulation changes over the past 130 years there is renewed interest as to the impact of future climate change on temperate alpine glaciers because of their role as indicators of past and ongoing changes and due to their possible involvement in sea level rise substantial changes in termini of new zealand glaciers since the nineteenth century are compared with variations in atmospheric circulation patterns over the southwest pacific region reconstructed sea level pressure patterns are used back to 1911 atmospheric circulation indices obtained from pressure differences between appropriate stations are extended back to the 1860s circulation anomalies are examined for winter related to glacier accumulation and for summer related to glacier ablation behaviour of glacier termini is found to be strongly linked with circulation changes especially in summer latitudinal shifts in the southern margin of the subtropical high pressure zone are identified as important an advance of some glaciers since 1980 is consistent with circulation changes over the new zealand region induced by two large el nino events

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

glacial advance and stagnation caused by rock avalanches abstract new model results show that a glacier advance caused by deposition of a rock avalanche on the ice will be followed by stagnation of the advanced ice lobe producing distributed hummocky deposits quite different from the single moraine ridges typically dated in paleoclimatic reconstructions we obtain these results using a numerical flow line glacier model with superimposed rock debris in particular our results imply that the single moraine ridge known as the waiho loop of the franz josef glacier new zealand is not the result of an advance triggered by a rock avalanche else there would be a widespread hummocky glacial stagnation deposit associated with it

multicentury glacier fluctuations in the swiss alps during the holocene subfossil remains of wood and peat from six swiss glaciers found in proglacial fluvial sediments indicate that glaciers were smaller than the 1985 reference level and climatic conditions allowed vegetation growth in now glaciated basins an extended data set of swiss glacier recessions consisting of 143 radiocarbon dates is presented to improve the chronology of glacier fluctuations a comparison with other archives and dated glacier advances suggests 12 major recession periods occurring at 9850 9600 93008650 85508050 77007550 74506550 61505950 57005500 52004400 43003400 28002700 21501850 14001200 cal yr bp it is proposed that major glacier fluctuations occurred on a multicentennial scale with a changing pattern during the course of the holocene after the younger dryas glaciers receded to a smaller extent and prolonged recessions occurred repeatedly culminating around 7 cal kyr bp after a transition around 6 cal kyr bp weak fluctuations around the present level dominated after 3 6 cal kyr bp less frequent recessions interrupted the trend to advanced glaciers peaking with the prominent little ice age this trend is in line with a continuous decrease of summer insolation during the holocene

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

importance of sampling across an assemblage of glacial landforms for interpreting cosmogenic ages of deglaciation deglaciation chronologies for some sectors of former ice sheets are relatively poorly constrained because of the paucity of features or materials traditionally used to constrain the timing of deglaciation in areas without good deglaciation varve chronologies and or without widespread occurrence of material that indicates the start of earliest organic radiocarbon accumulations suitable for radiocarbon dating typically only general patterns and chronologies of deglaciation have been deduced however mid latitude ice sheets that had warm based conditions close to their margins often produced distinctive deglaciation landform assemblages including eskers deltas meltwater channels and aligned lineation systems because these features were formed or significantly altered during the last glaciation boulder or bedrock samples from them have the potential to yield reliable deglaciation ages using terrestrial cosmogenic nuclides tcn for exposure age dating here we present the results of a methodological study designed to examine the consistency of tcn based deglaciation ages from a range of deglaciation landforms at a site in northern norway the strong coherence between exposure ages across several landforms indicates great potential for using tcn techniques on features such as eskers deltas and meltwater channels to enhance the temporal resolution of ice sheet deglaciation chronologies over a range of spatial scales

lichenometric dating of the little ice age maximum in mt cook national park southern alps new zealand lichenometric dating studies using the yellow green rhizocarpon subgenus at the eugenie hooker mueller and tasman glaciers in mt cook national park southern alps new zealand reveal a little i

latest pleistocene and holocene alpine glacier fluctuations in scandinavia abstract during the early holocene abrupt decadal to centennial scale climate variations caused significant glacier variations in norway increased freshwater inflow to the north atlantic and arctic oceans has been suggested as one of the most likely mechanisms to explain the abrupt and significant lateglacial and early holocene climatic events in nw europe the largest early holocene glacier readvances occurred 11 200 10 500 10 100 9700 9200 and 8400 8000 cal yr bp the studied norwegian glaciers apparently melted away at least once during the early mid holocene the period with the most contracted glaciers in scandinavia was between 6600 and 6000 cal yr bp subsequent to 6000 cal yr bp the glaciers started to advance and the most extensive glaciers existed at about 5600 4400 3300 2300 1600 cal yr bp and during the little ice age times with overall less glacier activity were apparently around 5000 4000 3000 2000 and 1200 cal yr bp it has been proposed that several glacier advances occurred in scandinavia including northern sweden at 8500 7900 7400 7200 6300 6100 5900 5800 5600 5300 5100 4800 4600 4200 3400 3200 3000 2800 2700 2000 1900 1600 1200 1000 and 700 200 cal yr bp glaciers in northern sweden probably reached their greatest little ice age extent between the 17th and the beginning of the 18th centuries evidence for early holocene glacier advances in northern scandinavia however has been questioned by more recent multi disciplinary studies the early to mid holocene glacier episodes in northern sweden may therefore be questioned most norwegian glaciers attained their maximum little ice age extent during the mid 18th century cumulative glacier length variations in southern norway based on marginal moraines dated by lichenometry and historic evidence show an overall retreat from the mid 18th century until the 1930s 40s subsequently most norwegian glaciers retreated significantly maritime outlet glaciers with short frontal time lags 15 20 years continued their retreat to the 1970s and 1980s however maritime glaciers started to advance as a response to higher winter accumulation during the first part of the 1990s after 2000 several of the observed glaciers have retreated remarkably fast annual frontal retreat 100 m mainly due to high summer temperatures the general glacier retreat during the early holocene and the neoglacial advances after 6000 cal yr bp are in line with orbital forcing due to the decrease of northern hemisphere summer solar insolation and the increase in winter insolation in addition regional weather modes such as the north atlantic oscillation nao and the arctic oscillation ao play a significant role with respect to decadal and multi decadal climate variability

too young or too old evaluating cosmogenic exposure dating based on an analysis of compiled boulder exposure ages cosmogenic exposure dating has greatly enhanced our ability to define glacial chronologies spanning several global cold periods and glacial boulder exposure ages are now routinely used to constrai

proliferation and demise of deep sea corals in the mediterranean during the younger dryas abstract uranium series and radiocarbon ages are reported for deep sea corals madrepora oculata desmophyllum dianthus lophelia pertusa and caryophyllia smithii from the mediterranean sea u series dating indicates that deep sea corals have persisted in the mediterranean for over 480 000 years especially during cool interstadial periods the most prolific period of growth however appears to have occurred within the younger dryas yd period from 12 900 to 11 700 years bp followed by a short 330 years phase of post yd coral growth from 11 230 to 10 900 years bp this indicates that deep sea corals were prolific in the mediterranean not only during the return to the more glacial like conditions of the yd but also following the rapid deglaciation and transition to warmer conditions that followed the end of the yd surprisingly there is a paucity last glacial maximum lgm coral ages implying they were largely absent during this period when cold water conditions were more prevalent radiocarbon ages show that the intermediate depth waters of the mediterranean generally had 14 c compositions similar to surface waters indicating that these waters were extremely well ventilated the only exception is a narrow period in the yd 12 500 100 years bp when several samples of lophelia pertusa from the ionian sea had 14 c values falling significantly below the marine curve using a refined approach isolation ages isol of 300 years to 500 years are estimated for these intermediate 800 1000 m depth waters relative to surface marine waters indicating a reduction or absence of deep water formation in the ionian and adjacent adriatic seas during the yd contrary to previous findings we find no evidence for widespread intrusion of low 14 c atlantic waters into the mediterranean prolific growth of deep sea corals in the mediterranean ended abruptly at 10 900 years bp with many of the coral bearing mounds on the continental slopes being draped in a thin veneer of mud their demise is attributed to a number of factors including the direct loss of habitat due to high sedimentation that accompanied glacial meltwater pulses together with rising temperatures that would have finally pervaded the deeper water of the mediterranean following the onset of holocene warming

the schmidt hammer in rock material characterization the schmidt hammer provides a quick and inexpensive measure of surface hardness that is widely used for estimating the mechanical properties of rock material however a number of issues such as hammer type normalization of rebound values specimen dimensions surface smoothness weathering and moisture content and testing data reduction and analysis procedures continue to influence the consistency and reliability of the schmidt hammer test results this paper presents a a critical review of these basic issues and b the results of tests conducted on granitic rocks of various weathering grades in the light of the conclusions of this review it was found that a very good correlation exists between l and n hammer rebound values and that both hammers are fairly sensitive to the physical properties particularly to dry density though less so to effective and total porosities the n hammer producing a lesser scatter in the data proved to be more efficient than the l hammer in predicting uniaxial compressive strength and young s modulus the exponential form of the correlation curves was found to reflect microstructural changes during the course of weathering and the differences in the probing scales or mechanisms in the means of measuring these mechanical properties and could be generalized to other crystalline igneous rocks the possibility of predicting weathering grades from rebound values was also explored the changes in the rebound values during multiple impacts at a given point produced a better indication of the weathering grade than a single impact value it was concluded that increasing the impact energy and plunger tip diameter should significantly reduce the scatter in coarse grained weathered rocks and hence improve the reliability of the schmidt hammer as a rock material characterization tool

the non tropical coral cladocora caespitosa as the new climate archive for the mediterranean high resolution weekly trace element systematics abstract high resolution weekly laser ablation icp ms trace element analyses b sr u mg ba are reported for the scleractinian coral cladocora caespitosa collected from the northern adriatic sea geochemical ratios sr ca b ca mg ca u ca ba ca were measured in a 38 mm long 10 years growth external coralline portion wall region and generally exhibit a close relationship with the in situ measured weekly fortnightly data on sea surface temperature sst available for the last 6 years in particular b ca ratios tuned to fine scale variations in sst show a high degree of correlation r 0 856 n 136 with sst and indicate that coral calcification only occurs above a minimum temperature threshold of 14 16 c in addition the ranges of trace element variability are larger than those typically recorded in tropical corals consistent with the large seasonal variations in sst of the adriatic this study thus demonstrates the feasibility of extracting and exploiting high resolution geochemical records from non tropical corals such as c caespitosa as a proxy for sst

age assessment and implications of late quaternary periglacial and paraglacial landforms on muckish mountain northwest ireland based on schmidt hammer exposure age dating shd abstract schmidt hammer exposure age dating shd was applied to a variety of late quaternary periglacial and paraglacial landforms composed of coarse rock debris on muckish mountain northwest ireland landform ages were determined using a linear high precision age calibration curve derived from young and old control surfaces of known age on the same rock type the shd ages represent maximum estimates of the time elapsed since the boulders stabilised and the landforms became inactive most ages are also minimum estimates for the start of landform development because older boulders are buried beneath the sampled surface boulders ages and 95 confidence intervals obtained for blockfield boulder lobes and talus indicate these features were likely active during several of the early holocene cold events evidenced in greenland ice cores and north atlantic sediment records activity ceased at different times 9 7 ka bp these landforms are the first indication of a geomorphological response to early holocene cooling in the oceanic mountains of ireland late holocene ages obtained for rock slope failure run out debris and debris cone boulders overlap with shifts to cooler and or wetter conditions including the little ice age geomorphological impacts associated with these changes in climate have not previously been recorded in the irish uplands the shd results indicate that previously implied timings for the stabilisation of some accumulations of coarse rock debris on mountain slopes are in need of revision

correlation of late quaternary moraines impact of climate variability glacier response and chronological resolution abstract the last decade has seen a global surge in the number and resolution of well dated geomorphological reconstructions of mountain glacier fluctuations and former ice sheet extents this has been facilitated by the widespread deployment of large samples of terrestrial cosmogenic nuclide dating tcnd allowing more sophisticated probability analyses for reducing the statistical uncertainty of moraine ages and testing of correlations at local regional and hemispheric scales geochronological advances in the field laboratory and on model calibration have taken place in parallel with modelling of palaeoclimate based on glacier reconstructions and of glacier sensitivity to temperature and precipitation forcing in spite of these advances basic conceptual issues remain this review questions whether the technical leap forward in dating has encouraged us to over reach our interpretive limits particularly in terms of the concept and practice of correlation we propose that to enable reliable correlation glacier chronologies should first be examined for their climatic integrity spatial coherence and chronological robustness even with excellent dating interpretive complexity remains due to complex climate signals and glacier response characteristics and to erosion censoring of the landform record all are issues which must be addressed to avoid either spurious lumping correlation or splitting differentiation of glacier chronologies and thus misinterpretation of the climatic significance of reconstructed glacier advances we suggest that the reliability of correlation is no better than the weakest link in the chain of reasoning which connects climatic fluctuations with dated landforms and sediments improved dating means that poor chronological resolution is less likely to be the limiting factor for correlation but shifts the focus onto other less quantifiable sources of uncertainty these conceptual statements are exemplified with reference to holocene glacial chronologies of contrasting mid latitude environments in southern norway iceland and new zealand

the schmidt hammer as a relative age dating tool and its potential for calibrated age dating in holocene glaciated environments the schmidt hammer is a relatively cheap portable sturdy instrument with proven value over the last two decades or so in rapidly dating coarse inorganic deposits of diverse origins early views were that its dating role was limited to distinguishing recently exposed from much older typically either a few sites of possibly different ages or occasional older surfaces amongst many young sites were studied more recently calibration curves based on individual r value means from small numbers 2 4 of sites of known ages have been used to estimate the ages of undated sites we present schmidt hammer rebound r values from 28 little ice age and younger 23 preboreal and 7 younger dryas glaciated surfaces in southern norway in order first to test rigorously the robustness of the instrument as a relative age dating tool despite being obtained from different surfaces moraines glaciofluvial deposits and bedrock and varied metamorphic lithologies the r value overall means and 95 confidence intervals for the little ice age preboreal and younger dryas age categories respectively 60 0 1 6 41 6 1 4 and 34 2 2 0 are statistically significantly different only two outlying sites in the two younger age categories have overlapping confidence intervals demonstrating remarkable robustness in differentiating early and late holocene surfaces the distinction between preboreal and younger dryas sites with terminal dates 2000 years apart is less clear but still statistically significant though possibly partly because of enhanced weathering conditions at the predominantly well vegetated younger dryas sites second we examine the feasibility and desirability of controlling non age related factors including some previously considered critical instrument wear operator bias initial rock surface texture which emerge either as less important than previously argued or as relatively unimportant together with others previously unreported e g long term changes in lichen soil snow and vegetation covers third we investigate the potential for calibrated age dating by applying exploratory linear rates of r value decline to selected combinations of sites the results suggest that error limits of ca 700 to 1600 years should be achievable over the holocene timescale this improved dating capability however will require adequate numbers of site means not only for each age category used to define these curves but also for each set of test surfaces of the same ages recommendations are made for a suitable sampling protocol for developing further the schmidt hammer as a calibrated age dating tool

holocene glacier variation chronology of the smorstabbtindan massif jotunheimen southern norway and the recognition of century to millennial scale european neoglacial events new stratigraphic evidence for the holocene history of three glaciers in central jotunheimen southern norway is presented and the implications for century to millennial scale glacier and climatic variability are considered minerogenic layers in seven stream bank mires flooded episodically by glaciofluvial meltwater are dated by 79 new radiocarbon age estimates a revised chronology for glacier variations in smorstabbtindan suggests a three phase holocene 1 an early holocene deglaciation phase 11500 9500 cal bp characterized by readvances of ice sheet remnants 2 a mid holocene phase with relatively small or absent glaciers 9500 5000 cal bp and 3 a late holocene phase of enlarged and fluctuating glaciers the last 5000 years seven millennial scale neoglacial events smorstabbtindan i vii during which glaciers were larger than at present for most of the time are dated to 10 400 9600 erdalen event 8400 7650 finse event 4800 3900 3200 2550 2350 1700 1400 750 and 500 0 cal

holocene and latest pleistocene alpine glacier fluctuations a global perspective abstract alpine glacier fluctuations provide important paleoclimate proxies where other records such as ice cores tree rings and speleothems are not available about 20 years have passed since a special issue of quaternary science reviews was published to review the worldwide evidence for holocene glacier fluctuations since that time numerous sites have been discovered new dating techniques have been developed and refined climatic hypotheses have been proposed that contribute to a better understanding of earth s climate system this special volume includes 12 papers on holocene and latest pleistocene alpine glacier fluctuations that update the seven review papers from 1988 major findings of these 12 papers include the following many but certainly not all alpine areas record glacier advances during the younger dryas cold interval most areas in the northern hemisphere witnessed maximum glacier recession during the early holocene with some glaciers disappearing although a few sites yield possible evidence for advances during the 8 2 ka cooling event in contrast some alpine areas in the southern hemisphere saw glaciers reach their maximum post glacial extents during the early to middle holocene in many parts of the globe glaciers reformed and or advanced during neoglaciation beginning as early as 6 5 ka neoglacial advances commonly occurred with millennial scale oscillations with many alpine glaciers reaching their maximum holocene extents during the little ice age of the last few centuries although the pattern and rhythm of these glacier fluctuations remain uncertain improved spatial coverage coupled with tighter age control for many events will provide a means to assess forcing mechanisms for holocene and latest pleistocene glacial activity and perhaps predict glacier response to future impacts from human induced climate change

cosmogenic 10be and 26al ages of holocene moraines in southern norway ii evidence for individualistic responses of high altitude glaciers to millennial scale climatic fluctuations abstract 10be and 26al exposure ages are reported for boulder moraine ridges in front of two high altitude cirque glaciers austanbotnbreen jotunheimen and ostre tundradalskyrkjabre breheimen in southern norway ages and 1 external uncertainties for austanbotnbreen moraines range from 7 4 0 75 ka to 8 7 0 9 ka when no adjustment for snow shielding is made with the maximum conceivable snow cover effect 2 m thick a density of 0 2 g cm3 6 months duration at the exposed site the resulting adjusted 7 7 0 8 to 10 9 1 3 ka as well as unadjusted ages suggest moraine formation possibly during both the 8 2 ka event finse event in southern norway and the erdalen event c 10 0 ka in contrast ages obtained for the outer ridges of the large moraine complex in front of ostre tundradalskyrkjabre range from 1 1 0 3 ka to 1 9 0 4 ka assuming no snow shielding assuming extreme snow lie conditions 4 m thick 0 2 g cm3 density 6 months duration at this more sheltered site the adjusted ages

isrm suggested method for determination of the schmidt hammer rebound hardness revised version with its portable simple and affordable attributes the schmidt hammer sh is an ideal index apparatus which underlies its increasing popularity and expanding range of applications the sh rebound hardness value r is perhaps the most frequently used index in rock mechanics practice for estimating the uniaxial compressive strength ucs and the modulus of elasticity e of intact rock both in laboratory conditions and in situ the sh is also widely used for estimating the ucs of discontinuity walls and assessing the workability excavatability and boreability of rocks by mechanical means cutting polishing milling crushing and fragmentation processes in quarrying drilling and tunneling

millennial scale depositional cycles from the holocene of the po plain italy the holocene depositional history of southeastern po plain on time scales of 103 yr is reconstructed based upon integrated sedimentological and micropalaeontological analyses of nine continuously cored boreholes about 40 m deep major palaeoenvironmental changes include the rapid landward migration of a barrier estuary lagoon system during the early middle holocene transgressive systems tract tst followed by extensive delta progradation in the last 6000 yr highstand systems tract hst detailed facies analysis of cores combined with the identification of 12 microfossils benthic foraminifer and ostracod associations allow an ultra high resolution sequence stratigraphic framework to be reconstructed particularly eight small scale high frequency cycles about 3 5 m thick and spanning intervals of time of about 1000 yr can be physically traced throughout the study area interpretation of these cycles which are invariably bounded by sharp flooding surfaces and generally show internal shallowing upward trends parasequences indicates that relative sea level changes during the holocene were episodic and punctuated by rapid phases of sea level rise followed by periods of stillstand or decreasing sea level rise from seaward to landward locations parasequence boundaries document beach barrier migration bay head delta abandonment and increasing accommodation in the coastal plain the ensuing phases of sea level stillstands resulted in the progressive filling of the newly formed accommodation space through beach progradation extensive mud deposition in behind barrier lagoonal estuarine and marsh deposits and aggradation in bay head delta systems at the head of estuaries eustacy appears to be the major controlling factor of the retrogradational stacking pattern of parasequences within the tst by contrast a complex interplay of eustacy sediment supply and subsidence with an increasing influence of autocyclic mechanisms such as channel avulsion and delta lobe abandonment controlled facies architecture within the hst the maximum flooding surface cannot be assumed to be synchronous its timing being strongly dependent upon local variations in sediment influx and subsidence this study shows that the micropalaeontologic characterization of mud prone coastal plain and estuarine successions in terms of water depth and salinity can lead to very accurate sequence stratigraphic interpretations allowing identification of parasequence boundaries that may not be detected by conventional stratigraphic approach

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

schmidt hammer exposure age dating shd of sorted stripes on juvflye jotunheimen central south norway morphodynamic and palaeoclimatic implications abstract measurements with an electronic schmidt hammer rockschmidt were conducted on 23 sites of sorted stripes periglacial patterned ground on juvflye jotunheimen central south norway all were located above the current lower limit of alpine permafrost performing schmidt hammer exposure age dating shd based on application of a new local age calibration equation for rrock values yielded shd ages between 7975 370 and 6660 355 years ago which are closely comparable to results obtained previously from sorted circles at the same location the age estimates are interpreted as composite ages indicative of upfreezing of boulders lateral sorting and subsequent stabilisation formation of patterned ground essentially ceased with the onset of the regional holocene thermal maximum htm neither sorted stripe sites at higher altitude continuously underlain by permafrost during the entire holocene nor those at lower altitudes affected by re aggradation of permafrost in the late holocene show signs of significant recent morphodynamic activity likely explanations for early to mid holocene stabilisation include 1 substantial changes of soil moisture conditions and related thermodynamics within the active layer affecting frost action 2 loss of fine grained substrate matrix from the coarse stripes and hence reduced frost susceptibility and 3 exhaustion of supply of boulders from the fines dominated areas whereas the sorted stripe data set as a whole did not reproduce the altitudinal gradient characteristic of sorted circles on juvflye the strength of the relationship between sorted stripe mean rrock values and altitude increased with declining slope gradient although interpretation of shd ages for patterned ground remains challenging this successful application of the electronic schmidt hammer with its increased efficiency and technical improvements over the mechanical schmidt hammer offers considerable potential for future shd studies in both morphodynamic and palaeoclimatic contexts

structure and origin of holocene cold events abstract the present interglacial the holocene spans the period of the last 11 700 years it has sustained the growth and development of modern society the millennial scale decreasing solar insolation in the northern hemisphere summer lead to northern hemisphere cooling a southern shift of the intertropical convergence zone itcz and a weakening of the northern hemisphere summer monsoon systems on the multidecadal to multicentury scale periods of more stable and warmer climate were interrupted by several cold relapses at least in the northern hemisphere extra tropical area based on carefully selected 10 000 year long time series of temperature and humidity precipitation as well as reconstructions of glacier advances the spatiotemporal pattern of six cold relapses during the last 10 000 years was analysed and presented in form of a holocene climate atlas hoclat see http www oeschger unibe ch research projects holocene atlas a clear cyclicity was not found and the spatiotemporal variability of temperature and humidity precipitation during the six specific cold events 8200 6300 4700 2700 1550 and 550 years bp was very high different dynamical processes such as meltwater flux into the north atlantic low solar activity explosive volcanic eruptions and fluctuations of the thermohaline circulation likely played a major role in addition internal dynamics in the north atlantic and pacific area including their complex interaction were likely involved

the use of in situ produced cosmogenic radionuclides in glaciology and glacial geomorphology the usefulness of in situ produced cosmogenic radionuclides in constraining glacial chronologies through exposure age dating has been demonstrated in numerous studies however an understanding of cosmogenic radionuclide techniques and their uncertainties opens up a wide range of other potential applications in glaciology and glacial geomorphology recently developed applications include estimation of spatial and temporal variations in the depth of glacial erosion from cosmogenic radionuclide inheritance which provides important constraints on process based erosion models and burial dating which can provide chronological control for glacial advances and the onset of till deposition an interesting new application currently at the level of theoretical model development concerns the unraveling of complex exposure and burial histories overall in situ produced cosmogenic radionuclide techniques provide a means with which to constrain a wide range of ice sheet and glacial models over time scales of a thousand to a few million years

latest pleistocene and holocene glacier fluctuations in western canada we summarize evidence of the latest pleistocene and holocene glacier fluctuations in the canadian cordillera our review focuses primarily on studies completed after 1988 when the first comprehensive review of such evidence was published the cordilleran ice sheet reached its maximum extent about 16 ka and then rapidly decayed some lobes of the ice sheet valley glaciers and cirque glaciers advanced one or more times between 15 and 11 ka by 11 ka or soon thereafter glacier cover in the cordillera was no more extensive than at the end of the 20th century glaciers were least extensive between 11 and 7 ka a general expansion of glaciers began as early as 8 4 ka when glaciers overrode forests in the southern coast mountains it culminated with the climactic advances of the little ice age holocene glacier expansion was not continuous but rather was punctuated by advances and retreats on a variety of timescales radiocarbon ages of wood collected from glacier forefields reveal six major periods of glacier advance 8 59 8 18 7 36 6 45 4 40 3 97 3 54 2 77 1 71 1 30 ka and the past millennium tree ring and lichenometric dating shows that glaciers began their little ice age advances as early as the 11th century and reached their maximum holocene positions during the early 18th or mid 19th century our data confirm a previously suggested pattern of episodic but successively greater holocene glacier expansion from the early holocene to the climactic advances of the little ice age presumably driven by decreasing summer insolation throughout the holocene proxy climate records indicate that glaciers advanced during the little ice age in response to cold conditions that coincided with times of sunspot minima priority research required to further advance our understanding of late pleistocene and holocene glaciation in western canada includes constraining the age of late pleistocene moraines in northern british columbia and yukon territory expanding the use of cosmogenic surface exposure dating techniques using multi proxy paleoclimate approaches and directing more of the research effort to the northern canadian cordillera

relative and absolute dating of land surfaces abstract the dating of land surfaces has long posed problems for geomorphologists relative methods stratigraphic geomorphic topographic are sound and convincing exhumed forms may complicate identification and relationships for both epigene and etch forms have been buried and exhumed but in tectonically undisturbed areas the higher surfaces are older than those preserved at lower levels also surfaces have an age range the relationship of surfaces with volcanic deposits old shorelines and genetically related sedimentary sequences provides sound ages and correlation with dated duricrusts and faults is also useful there are no temporal limits to relative dating for the methods are equally applicable to the dating say of proterozoic surfaces as of those of pleistocene age the disadvantage of such methods is that the necessary evidence is frequently either not preserved or not exposed the so called absolute physical numerical methods and especially those based on exposure age dating with in situ cosmogenic radionuclides are appealing because they produce direct numerical ages and appear to be widely applicable but there are severe temporal limitations and sampling problems complicate and may invalidate interpretation absolute age determinations must be consistent with the stratigraphic and geomorphologic settings the best results are obtained when physicists and earth scientists pool their knowledge and experience a background in local and regional geology is especially important

latest pleistocene and holocene glacier variations in the european alps in the alps climatic conditions reflected in glacier and rock glacier activity in the earliest holocene show a strong affinity to conditions in the latest pleistocene younger dryas glacier advances in the alps related to younger dryas cooling led to the deposition of egesen stadial moraines egesen stadial moraines can be divided into three or in some cases even more phases sub stadials moraines of the earliest and most extended advance the egesen maximum stabilized at 12 2 1 0 ka based on 10be exposure dating at the schonferwall tyrol austria and the julier pass outer moraine switzerland final stabilization of moraines at the end of the egesen stadial was at 11 3 0 9 ka as shown by 10be data from four sites across the alps from west to east the sites are piano del praiet northwestern italy grosser aletschgletscher central switzerland julier pass inner moraine eastern switzerland and val viola northeastern italy there is excellent agreement of the 10be ages from the four sites in the earliest holocene glaciers in the northernmost mountain ranges advanced at around 10 8 1 1 ka as shown by 10be data from the kartell site northern tyrol austria in more sheltered drier regions rock glacier activity dominated as shown for example at julier pass and larstig valley tyrol austria new 10be dates presented here for two rock glaciers in larstig valley indicate final stabilization no later than 10 5 0 8 ka based on this data we conclude the earliest holocene between 11 6 and about 10 5 ka was still strongly affected by the cold climatic conditions of the younger dryas and the preboreal oscillation with the intervening warming phase having had the effect of rapid downwasting of egesen glaciers at or slightly before 10 5 ka rapid shrinkage of glaciers to a size smaller than their late 20th century size reflects markedly warmer and possibly also drier climate between about 10 5 ka and 3 3 ka conditions in the alps were not conducive to significant glacier expansion except possibly during rare brief intervals past tree line data from kaunertal tyrol austria in concert with radiocarbon and dendrochronologically dated wood fragments found recently in the glacier forefields in both the swiss and austrian alps points to long periods during the holocene when glaciers were smaller than they were during the late 20th century equilibrium line altitudes ela were about 200 m higher than they are today and about 300 m higher in comparison to little ice age lia elas the larstig rock glacier site we dated with 10be is the type area for a postulated mid holocene cold period called the larstig oscillation presumed age about 7 0 ka our data point to final stabilization of those rock glaciers in the earliest holocene and not in the middle holocene the combined data indicate there was no time window in the middle holocene long enough for rock glaciers of the size and at the elevation of the larstig site to have formed during the short infrequent cold oscillations between 10 5 and 3 3 ka small glaciers less than several km2 may have advanced to close to their lia dimensions overall the cold periods were just too short for large glaciers to advance after 3 3 ka climate conditions became generally colder and warm periods were brief and less frequent large glaciers for example grosser aletschgletscher advanced markedly at 3 0 2 6 ka around 600 ad and during the lia glaciers in the alps attained their lia maximum extents in the 14th 17th and 19th centuries with most reaching their greatest lia extent in the final 1850 1860 ad advance

the influence of rock mass strength on glacial valley cross profile morphometry a case study from the southern alps new zealand the erosional morphology in the vicinity of the main divide of the southern alps and fiordland new zealand appears to be a product of the interaction between alpine fault induced tectonic processes rock mass strength of the uplifted and eroded bedrock and the processes acting to denude the developing mountain landscape the magnitude of the effects of glacial erosion on the landscape is directly controlled by the size and physical properties of the glaciers whilst the form of the trough is a direct consequence of the rock mass strength rms properties of the slope rock realistic models of development of the cross profile shape of glacial valleys must take into consideration the rms properties of the eroded substrate

a revised approach to discriminating sediment transport histories in glacigenic sediments in a temperate alpine environment a case study from fox glacier new zealand clast shape measurements have developed into a standard method for reconstructing the transport histories of sediments in glacial environments the majority of studies use the ra c40 covariance approach with some researchers routinely including clasts of varying lithologies within their samples the corollary is that variable lithological properties may control clast form and roundness rather than debris transport mechanisms despite this the role of lithology on clast shape in glacial environments has rarely been analysed furthermore some studies have reported difficulties in using the ra c40 co variance plot in discriminating clasts that have undergone subglacial transport and clasts that have been modified by fluvial activity results from a glacierized valley in a temperate alpine setting indicate that detailed analysis of clast shape where samples are of uniform lithology although time consuming is a useful tool in the investigation of deposits in glaciated environments copyright 2012 john wiley sons ltd

holocene glacier chronologies are high resolution global and inter hemispheric comparisons possible in the context of reconstruction of holocene glacier chronologies there has been a clear tendency during the past few decades towards imprecise use of the term high resolution furthermore it seems to be increasingly assumed that recently developed terrestrial cosmogenic nuclide dating tcnd is replacing earlier dating methods although recent glaciological knowledge clearly reveals the futility of oversimplified global and inter hemispheric correlation on the basis of few key sites such comparisons are widely attempted stimulated by the example of a recently published article relating to the southern alps of new zealand schaefer et al 2009 science 324 622 625 we highlight some related potential problems with the interpretation of holocene glacier chronologies in particular we consider 1 that the term high resolution should be applied only to decadal scale resolution or better and therefore not to tcnd based chronologies 2 that discontinuous moraine chronologies should not be ter

the schmidt hammer as a holocene calibrated age dating technique testing the form of the r value age relationship and defining the predicted age errors most recent developments of schmidt hammer exposure age dating shd as a calibrated age dating tool have been limited by the use of locations at two age control points this has necessitated 1 making assumptions about a linear r value age relationship and 2 basing predictions of age errors only on r value variance at the two age control points this paper analyses 9900 r values obtained from multiple age control points on a sequence of glacio isostatically raised shorelines with well constrained ages skuleskogen high coast world heritage site and environs gulf of bothnia northern sweden ranging from modern to 10 5 ka in age the sampling design involved 30 measurements on granite beach boulders from 30 sites at 11 age control points the r value age relationship is best described by a linear function ordinary least squares ols with an r 2 of 0 89 p 0 0001 predicted age errors are calculated using two approaches 1 ols regression which takes account of the uncertainties associated with the regression line and the age control points and 2 weighted total least squares wtls regression which in addition takes account of possible shoreline age errors and the heteroscedasticity of r value residuals with increasing age with both approaches 95 predicted age errors are relatively modest 355 455 years and 300 515 years respectively with larger r value variance and hence uncertainty for older surfaces and the possibility of further improvement from a more selective field sampling scheme that differentiates between age related and non age related rock surface variability our results also indicate that for certain lithologies and weathering environments it is possible to construct reliable calibrated age curves from relatively few age control points

mid to late holocene climate change an overview the last 6000 years are of particular interest to the understanding of the earth system because the boundary conditions of the climate system did not change dramatically in comparison to larger glacial interglacial changes and because abundant detailed regional palaeoclimatic proxy records cover this period we use selected proxy based reconstructions of different climate variables together with state of the art time series of natural forcings orbital variations solar activity variations large tropical volcanic eruptions land cover and greenhouse gases underpinned by results from general circulation models gcms and earth system models of intermediate complexity emics to establish a comprehensive explanatory framework for climate changes from the mid holocene mh to pre industrial time the redistribution of solar energy due to orbital forcing on a millennial timescale was the cause of a progressive southward shift of the northern hemisphere nh summer position of the intertropical convergence zone itcz this was accompanied by a pronounced weakening of the monsoon systems in africa and asia and increasing dryness and desertification on both continents the associated summertime cooling of the nh combined with changing temperature gradients in the world oceans likely led to an increasing amplitude of the el nin o southern oscillation enso and possibly increasingly negative north atlantic oscillation nao indices up to the beginning of the last millennium on decadal to multi century timescales a worldwide coincidence between solar irradiance minima tropical volcanic eruptions and decadal to multi century scale cooling events was not found however reconstructions show that widespread decadal to multi century scale cooling events accompanied by advances of mountain glaciers occurred in the nh e g in scandinavia and the european alps this occurred namely during the little ice age lia between ad w1350 and 1850 when the lower summer insolation in the nh due to orbital forcing coincided with solar activity minima and several strong tropical volcanic eruptions the role of orbital forcing in the nh cooling the southward itcz shift and the desertifi cation of the sahara are supported by numerous model simulations other simulations have suggested that the fingerprint of solar activity variations should be strongest in the tropics but there is also evidence that changes in the ocean heat transport took place during the lia at high northern latitudes with possible additional implications for climates of the southern hemisphere sh

schmidt hammer exposure age dating shd of late quaternary fluvial terraces in new zealand schmidt hammer sh r values are reported for surface clasts from numerically dated holocene and pleistocene fluvial terraces in the south island of new zealand the r values are combined with previously obtained weathering rind radiocarbon terrestrial cosmogenic nuclide and luminescence terrace ages to derive sh r value chronofunctions for greywacke clasts from four distinct locations our results show that different weathering rates affect the form of the sh r value versus age curve however a fundamental dependency between the two remains constant over timescales ranging from 102 to 105 years power law scaling constants suggest changes in clast weathering rates are primarily affected by climatic precipitation and temperature and sedimentologic variables source terrane petrology age uncertainties of 22 of the surface age suggest that schmidt hammer exposure age dating shd is a reliable calibrated age dating technique for fluvial terraces copyright 2013 john wiley sons ltd

catastrophic landslides glacier behaviour and moraine formation a view from an active plate margin the influence of large bedrock landslides rock avalanches on the behaviour of glaciers is incompletely recognised here we present an example from an active tectonic margin in south island new zealand where large earthquakes leave a significant imprint on glacial records we demonstrate that terminal moraines on the western side of the southern alps record both ordinary i e climate driven and landslide initiated glacial advances following consideration of the processes involved in rock avalanche initiated moraine construction we suggest ways of determining the nature of the advance that built the terminal moraine the implications of these observations are important in breaking the conventional linkage of individual terminal moraines with climate forcing

a comparison of the lichenometric and schmidt hammer dating techniques based on data from the proglacial areas of some icelandic glaciers abstract measurements of rhizocarpon section and schmidt hammer r values are reported from the proglacial geomorphic features on the forelands of the icelandic glaciers of kviarjokull holarjokull and heinabergsjokull oraefi and south vatnajokull sandfellsjokull and oldufellsjokull east m rdalsjokull and bruarjokull eyjabakkajokull and west snaefell north vatnajokull these data are used in reconstructions of patterns of glacier recession since the little ice age maximum and the geomorphic signals of climatic versus non climatic events are discussed age control was obtained from various dated substrates by utilizing historical accounts aerial photographs and grave stones three lichen growth rates are calculated a 0 51 mm a 1 corrected to 0 50 mm a 1 with a colonization lag time of

effects of rock avalanches on glacier behaviour and moraine formation although large rock avalanches are infrequent sediment production in active orogens is dominated by such events which may strongly influence geomorphic processes where rock avalanches fall onto glaciers they may affect glacier behaviour and moraine formation we outline the processes of rock avalanche initiation and motion and show that supraglacial deposits of rock avalanche debris have distinct sedimentological and thermal properties laboratory experiments on the effects of such debris on ice ablation are supplemented by field data from two rock avalanches in the southern alps new zealand their effects are compared with those of the thinner supraglacial debris that results from small rockfalls and melt out of englacial debris implications of rock avalanche debris cover for glacier behaviour are explored using a mass balance model of the franz josef glacier in new zealand demonstrating a likely supraglacial rock avalanche origin for the waiho loop moraine and considering the potential hazard of a large rock avalanche onto the present day glacier

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

holocene glacier variations in new zealand a review abstract in the central southern alps of new zealand ice surface lowering has exposed extensive sections of lateral moraines allowing investigation of moraine stratigraphy and genesis the presence of multiple superposed palaeosurfaces within moraine sequences allows recognition of any disturbances displacements or contamination of till layers and interbedded organic material radiocarbon dating of buried wood and soils allows comparison between the holocene glacial history of the eastern ranges and that of the westland region the periodicity of glacier response has been similar to both areas although the precise timing of events has differed due to local climatic and environmental factors in general glaciers in new zealand expanded about 5000 4500 4200 3700 3500 3000 2700 2200 1800 1700 1500 1100 900 700 600 and 400 100 bp

scaling factors for production rates of in situ produced cosmogenic nuclides a critical reevaluation abstract new scaling factors are presented describing the altitude and latitudinal dependence of production rates for in situ produced cosmogenic nuclides the new factors incorporate the influence of the non dipole contributions to the geomagnetic field on the cosmic ray flux the currently used scaling factors of lal earth planet sci lett 104 1991 424 439 are based on the assumption of a dipole field the overall strategy used in deriving the new scaling factors is however very similar to that of lal and relies on the same and or similar nuclear data in this reevaluation data are only used if the effective geomagnetic parameters inclination horizontal field strength can be reconstructed for the time of measurement the absorption free pathlengths for cosmic rays selected for this study are based on observational data at altitudes relevant for exposure age dating sea level to 7000 m at sea level and latitudes between 20 and 40 the new factors are up to 18 lower and at high altitudes more than 30 higher than those of lal in addition to accounting for the influence of the effective geomagnetic field and providing more applicable estimates of the new factors also allow for correction for the significant deviations from the standard pressure altitude relationship that exist in the atmosphere 10

application of a combination of dating techniques to reconstruct the lateglacial and early holocene landscape history of the albula region eastern switzerland landforms in val mulix and the albula region in eastern switzerland offer a detailed insight into the period between the oldest dryas until the early holocene to better understand lateglacial and holocene climate change in the central alps glacial moraines polished bedrock and periglacial rock glacier landforms were dated using a combined approach of numerical cosmogenic 10be and relative schmidt hammer weathering rind thickness dating techniques at high elevation sites near the last glacial maximum lgm trimline 10be exposure ages of glacially modified bedrock are between 11 2 ka and 13 5 ka this suggests the persistence of long lasting small local ice caps after the breakdown of the lgm ice domes or alternatively a reformation of ice perhaps during the younger dryas in val mulix we obtained one of the first ages for the daun stadial 14 7 ka moraines 14 9 1 8 ka supporting a pre bolling chronological position the age is in excellent agreement with the age of a boulder from an egesen i moraine located up valley which we postulate may be a daun moraine that was re occupied during the egesen stadial a boulder from an egesen ii moraine gave an age of 10 7 ka which is similar to ages of egesen ii moraines at other sites in the alps 10be ages from boulders found on a relict rock glacier in val mulix indicate that the main active phase lasted from the lateglacial until the early holocene the derived mean annual flow rate is of the order of decimetres which is in accordance with values stated in the literature based on measuring active rock glaciers in the alps exposure ages from a glacially polished rock barrier showed that this area was ice free at the end of the younger dryas 9 0 0 7 ka and 11 9 0 9 ka the polished bedrocks are located a few hundred meters down valley from the little ice age lia moraines this gives direct evidence of a fast ice retreat towards the end of the younger dryas with glacier length variations that did not exceed the 1850 ad extension little ice age maximum surface exposure dating is however limited by several methodological constraints the choice of suitable snow depths plays a crucial role in the calculation of the 10be ages shielding of surfaces from cosmic rays by snow can significantly influence the exposure age and variations in the estimated annual snowfall in the albula region since the lgm is therefore a potential source of considerable uncertainty in our measurements while the measurement of weathering rind thicknesses turned out to be an appropriate tool to support the reconstruction of lateglacial landscape evolution schmidt hammer r values were less helpful the r values enabled a temporal distinction of landforms within the holocene lia moraine active rock glaciers but not within the lateglacial from a methodological point of view the different dating methods enabled a cross checking an extended interpretation of the data and a more accurate estimate of the possible sources of error

the use of the schmidt hammer and equotip for rock hardness assessment in geomorphology and heritage science a comparative analysis rapid field based measurements of rock hardness are of use in investigating many geomorphological and heritage science problems several different methods are now available for taking such measurements but little work has been done to assess their comparability and strengths and weaknesses we review here the capabilities of two types of schmidt hammer classic n type and silver schmidt bl type alongside two types of equotip standard type d and piccolo for investigating rock hardness in relation to rock weathering on various types of sandstone and limestone as well as basalt and dolerite whilst the two schmidt hammers and the two equotips show comparable results when tested at 15 individual sites interesting differences are found between the equotip and schmidt hammer values which may reveal information about the nature of weathering on different surfaces operator variance is shown to be an issue in particular for the equotip devices which also exhibit higher variability in measurements and necessitate larger sample sizes carborundum pre treatment also has varying effects on the data collected depending on the nature of the surface studied the equotip devices are shown to be particularly useful on smaller blocks and in situations where edge effects may affect schmidt hammer readings we conclude that whilst each device contributes to geomorphological research they do not necessarily produce comparable information indeed using schmidt hammer and equotip in combination and looking at any differences in results may provide invaluable insights into the structure of the near surface zones and the nature of weathering processes copyright 2010 john wiley sons ltd

updrift river mouth migration on cuspate deltas two examples from the coast of tuscany italy the configuration of the arno and ombrone deltas italy is evaluated the terminal courses of the rivers forming these deltas face the dominant wave orthogonal this configuration came about during rapid delta progradation as a consequence of increased river sediment input due to widespread deforestation within the catchment area a prevailing phenomenon from the early middle ages to the xviii century the rivers attained and maintained their directions as the result of the increased accretion rate on the less exposed downdrift side of the delta on the more exposed updrift side delta growth caused the shoreline to gradually rotate so that it directly faced the waves approaching the coast here due to the lower refraction wave energy per shore unit increased whilst accretion rate decreased this rotation of the shoreline induced longshore inversion on the updrift side whereas today cusp erosion is restoring the original drift direction

the alps with little ice evidence for eight holocene phases of reduced glacier extent in the central swiss alps glacially deformed pieces of wood organic lake sediments and clasts of reworked peat have been collected in front of alpine glaciers since ad 1990 the palaeoglaciological interpretation of these organic materials is related to earlier phases of glacier recession surpassing that of today s shrunken glaciers and to tree growth and peat accumulation in the valleys now occupied by the glaciers glacial transport of the material is indicated by wood anatomy incorporated silt sand and gravel particles missing bark and deformed treerings a total of 65 samples have been radiocarbon dated so far and clusters of dates provide evidence of eight phases of glacier recession 9910 9550 9010 7980 7250 6500 6170 5950 5290 3870 3640 3360 2740 2620 and 1530 1170 calibrated years bp allowing for the timelag between climatic fluctuations glacier response and vegetation colonization these recession phases may lag behind climatic changes by 100 200 years

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

age constraints of rock glaciers in the southern alps new zealand exploring their palaeoclimatic potential two rock glaciers in the valley head of irishman stream in the central ben ohau range southern alps new zealand have been investigated using the electronic schmidt hammer silverschmidt longitu

comparison of electronic and mechanical schmidt hammers in the context of exposure age dating are q and r values interconvertible application of schmidt hammer exposure age dating shd to landforms has substantially increased in recent years the original mechanical schmidt hammer records r rebound values although the newly introduced electronic schmidt hammer silverschmidt facilitates greatly improved data processing it measures surface hardness differently recording q velocity values that are not a priori interconvertible with r values this study is the first to compare the performance of both instruments in the context of field based exposure age dating with a particular focus on the interconvertibility of r values and q values the study was conducted on glacially polished pyroxene granulite gneiss jotunheimen southern norway results indicate that mean q values are consistently 8 10 units higher than mean r values over the range of values normally encountered in the application of shd to glacial and periglacial landforms a convenient conversion factor of 10 units may therefore be appropriate for all but the softest rock types close to the technical resolution of the instruments the electronic schmidt hammer should therefore be regarded as a useful complement and potential replacement for the mechanical schmidt hammer conversion of published r values data to q values requires however careful control and documentation of instrument calibration copyright 2014 john wiley sons ltd