late holocene glacial activity of bridge glacier british columbia coast mountains bridge glacier is a prominent eastward flowing valley glacier located on the east side of the pacific ranges within the southern british columbia coast mountains the terminus of bridge glacier has retreated at rates up to 125 m year over the last 50 years and currently calves into proglacial bridge lake field investigations of the recently deglaciated terrain and moraines led to the discovery of detrital boles and glacially sheared stumps dendroglaciological analyses of this subfossil wood produced five radiocarbon controlled floating tree ring chronologies the relative age and stratigraphic location of these samples revealed that bridge glacier experienced at least four periods of significant advance during the late holocene a tiedemann aged advance ca 3000 14c years bp an unattributed advance ca 1900 14c years bp a first millennium advance ca 1500 14c years bp and a little ice age advance beginning ca 700 14c years bp lichenometric investigations at eight terminal and lateral moraine comple

contribution of icelandic ice caps to sea level rise trends and variability since the little ice age 1 in total icelandic ice caps contain 3600 km3 of ice which if melted would raise sea level by 1 cm here we present an overview of mass changes of icelandic ice masses since the end of the 19th century they have both gained and lost mass during this period changes in ice volume have been estimated both through surface mass balance measurements performed annually since 1990 and differencing of digital elevation models derived from various satellite and airborne observations while the glaciers showed little mass loss as the 20th century began losses increased rapidly after 1925 peaked in the 1930s and 1940s and remained significant until the 1960s after being near zero or even positive during the 1980s and early 1990s glacier mass budgets declined considerably and have since the mid 1990s shown an average annual loss of 9 5 1 5 gt a 1 contributing 0 03 mm a 1 to sea level rise since 1995 interannual variability in mass loss is high ranging from 2 7 to 25 3 1 5 gt a 1 corresponding to surface mass balances of 0 2 to 2 2 0 15 m we a 1 this variability is driven by climate fluctuations and also by transient reduction of albedo due to volcanic eruptions

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

lichenometric and radiocarbon dating of holocene glaciation cordillera blanca peru hfeasurements of rliizocurpoii subgenus rliizocurpo r thalli on moraines the ages of which are constrained by six radiocarbon dates two pre colombian structures and one historically dated flood dep6sit indicate that lichenometry can be used to estimate the age of stabilization of glacial deposits that date to the last c 7 ka on the west side of the cordillera blanca perlj 8 40 9040 s 77 00 77 40 w the preliminary growth curve for subgenus rtiizocurpan resembles those derived for alpine areas in alaska and colorado and can be subdivided into an initial rapid phase of growth c 0 4 mm yr that lasts c 100 years a c 500 to 1000 year long phase of decelerating growth and a period of slow linear growth 0 016 mm yr that commences after c loo0 years size clustering of subgenus riiizocurpoir thalli supports a four fold subdivision of cirque moraines at altitudes between 4200 and 4650 m the oldest moraines stabilized between c 7000 and 6ooo bp and the three younger groups between c 3350 and 1600 bp between c 1250 and 400 bp and within the last 100 years this subdivision is supported by limiting radiocarbon dates from the cordillera blanca and from several cordilleras in southern peni and indicates that the holocene glacial chronology of the cordillera blanca is the most complete heretofore recognized in the tropical andes

tree ring evidence of little ice age glacier advances in southern tibet the history of late holocene glacier fluctuations in eastern tibet was studied by determining the ages of trees growing on glacier deposits maximum tree ages yield minimum ages of ad 1760 and 1780 for moraine formation at the maximum extent of the little ice age glacier advances in two glacier forefields subsequent moraines could be dated to the beginning of the nineteenth and the beginning of the twentieth century larch trees from a third glacier forefield in southeastern tibet show evidence of glacier activity from 1580 to 1590 from the end of the eighteenth to the beginning of the nineteenth century and from 1860 to 1880 one glacier at mt gyalaperi recently advanced in both 1951 and 1987 periods of glacier advances can partly be correlated with periods of growth reductions in chronologies of total ring width and maximum latewood density derived from trees growing on slopes above the glacier valleys correlation functions with meteorological data suggest that maximum latewood density of subalpin

glacier variations in breheimen southern norway dating little ice age moraine sequences at seven low altitude glaciers moraine sequences in front of seven relatively low altitude glaciers in the breheimen region of central southern norway are described and dated using a multi proxy approach to moraine stratigraphy lichenometric dating based on the rhizocarpon subgenus is used to construct a composite moraine chronology which indicates eight phases of synchronous moraine formation ad 1793 1799 1807 1813 1845 1852 1859 1862 1879 1885 1897 1898 1906 1908 and 1931 1933 although the existence of a few cases of older moraines possibly dating from earlier in the eighteenth or late in the seventeenth centuries cannot be ruled out by lichenometry schmidt hammer r values from boulders on outermost moraine ridges suggest an absence of holocene moraines older than the little ice age twenty three radiocarbon dates from buried soils and peat associated with outermost moraines at three glaciers tverreggibreen storegrovbreen and greinbreen also indicate that the little ice age glacier maximum was the neoglacial maximum at most if not all glaciers several maximum age estimates for the little ice age glacier maximum range between the fifteenth and seventeenth centuries with the youngest from a buried soil being ad 1693 a pre little ice age maximum cannot be ruled out at greinbreen however where the age of buried peat suggests the outermost moraine dates from ad 981 1399 at variance with the lichenometric evidence glaciofluvial stratigraphy at tverreggibreen provides evidence for minor glacier advances about ad 655 963 and ad 1277 1396 respectively copyright 2003 john wiley sons ltd

holocene glacier activity at the southwestern part of hardangerjokulen central southern norway evidence from lacustrine sediments lacustrine sediments from lake isdalsvatn downstream from the southwestern margin of the plateau glacier hardangerjokulen central southern norway show that the lake received glacial meltwater until 7890 95 bp a thin bluish grey minerogenic silt layer probably reflects a short glacial re advance between 7005 90 and 6835 150bp after the latter date inflow of glacial meltwater ceased indicating that small or more probably no glaciers existed on the southwestern hard angerjokulen plateau a drop in organic content and a slight increase in detrital content inferred from magnetic susceptibility at 120cm depth in the core may indicate some glacier activity in the catchment from about 3400 bp textural changes at 50cm depth indicate increased neoglacial activity in the upper catchment area from 2265 80 bp differences in glacier chronologies between the southern and northern sectors of hardangerjokulen may be explained partly by different glacier responses to the precipitation and wind distribu

tubular structures of northern wairarapa new zealand as possible examples of ancient fluid expulsion in an accretionary prism evidence from field and petrographical observations

little ice age precipitation in jotunheimen southern norway recently published glaciological data from southern norway enable analysis of changes in glacier geometry since the little ice age lia and estimation of the magnitude of the lia precipitation anomaly glacier area extents in the jotunheimen region have been created for 2003 using glacier outlines derived from landsat and for the lia maximum about ad 1750 by using glacier outlines defined by moraines a 25 m digital terrain model from 1980 was used to derive inventory data for both times both inventories provide area and altitude range as well as length slope and aspect of the glaciers area altitude profiles a z for the lia maximum are calculated from the 1980 profiles by assuming that the area increase distribution a z was concentrated at low altitude and it integrates to the measured area difference between 1980 and the lia under this assumption the regionally averaged mean altitude change from 1980 to the lia z 68 m glacier mass balance measurements show that the mass balance gradie

timing and climate forcing of volcanic eruptions for the past 2 500 years volcanic eruptions contribute to climate variability but quantifying these contributions has been limited by inconsistencies in the timing of atmospheric volcanic aerosol loading determined from ice cores and subsequent cooling from climate proxies such as tree rings here we resolve these inconsistencies and show that large eruptions in the tropics and high latitudes were primary drivers of interannual to decadal temperature variability in the northern hemisphere during the past 2 500 years our results are based on new records of atmospheric aerosol loading developed from high resolution multi parameter measurements from an array of greenland and antarctic ice cores as well as distinctive age markers to constrain chronologies overall cooling was proportional to the magnitude of volcanic forcing and persisted for up to ten years after some of the largest eruptive episodes our revised timescale more firmly implicates volcanic eruptions as catalysts in the major sixth century pandemics famines and socioeconomic disruptions in eurasia and mesoamerica while allowing multi millennium quantification of climate response to volcanic forcing

briksdalsbreen western norway climatic effects on the terminal response of a temperate glacier between ad 1901 and 1994 annual measurements of the frontal variations of briksdalsbreen are compared with twentieth century records of summer temperature winter precipitation and mass budget to evaluate the effects of climatic change on the glacier fluctuations frontal variations are shown to be determined by both summer temperature and winter precipitation between ad 1901 and 1931 the glacier front was in a more or less stable position warm summers in the 1930s and 1940s caused a significant retreat of the glacier reaching a maximum rate of annual retreat of 84 m in 1948 cooler summers in the late 1940s led to a stabilization of the glacier front from 1952 between 1987 88 and 1993 94 the terminus advanced 231 m 155 m of which has occurred after 1992 the increased glacier net mass balance in western norway after the 1988 89 season resulted in the largest annual glacier advances measured this century at briksdalsbreen 75 and 80 m in 1992 93 and 1993 94 respectively present knowledge about glacier history in western n

asynchronous little ice age glacier fluctuations in iceland and european alps linked to shifts in subpolar north atlantic circulation abstract records of past glacier fluctuations are an important source of paleoclimate data and provide context for future changes in global ice volume in the north atlantic region glacier chronologies can be used to track the response of terrestrial environments to variations in marine conditions including circulation patterns and sea ice cover however the majority of glacier records are discontinuous and temporally restricted owing in part to the extensive advance of northern hemisphere glaciers during the little ice age lia the most recent and severe climate anomaly of the neoglacial period here we combine an absolutely dated and continuous record of langjokull ice marginal fluctuations with new reconstructions of sediment flux through the past 1 2 ka using varved sediments from hvitarvatn a proglacial lake in iceland s central highlands large spatial and temporal variations in sediment flux related to changing ice cap dimensions are reconstructed from six sediment cores and seismic reflection profiles sediment data reveal two discrete phases of ice expansion occurring ca 1400 to 1550 ad and ca 1680 to 1890 ad these advances are separated by a persistent interval of ice retreat suggesting that a substantial period of warming interrupted lia cold the pattern of icelandic glacier activity contrasts with that of european glaciers but shows strong similarities to reconstructed changes in north atlantic oceanographic conditions indicating differing regional responses to coupled ocean atmosphere sea ice variations our data suggest that subpolar north atlantic circulation dynamics may have led to coherent asynchronous glacier fluctuations during the mid lia and highlight the importance of circulation variability in triggering and transmitting multidecadal scale climate changes to nearby terrestrial environments

scandinavian glacial and climatic fluctuations during the holocene abstract historical documents and lichenometric studies give a detailed picture of the little ice age in scandinavia there was a large advance in norway which has been dated at a few places to 1750 small readvances during the retreat occurred around a d 1780 1810 1840 1850 1850 1870 1890 1910 and 1930 in sweden most of these advances have been recognized and in addition extensive advances are dated by lichenometry to around a d 1600 1650 and 1700 1720 soils buried beneath moraines often yield radiocarbon dates that are much too old methods dependent on these must therefore be used with care evidence for pre little ice age advances are often considered equivocal the most reliable information is probably provided by studies of lacustrine sediments combining information from all sources the most significant pre little ice age glacier advances most likely occurred in 7 5 5 1 4 5 3 2 2 8 2 2 1 9 and 1 5 1 1 radiocarbon ka bp advances that were less extensive or for which there is less evidence occurred around 6300 5600 2500 940 600 560 and 380 bp

tree ring based mass balance estimates for the past 300 years at peyto glacier alberta canada tree rings were used to reconstruct mass balance for peyto glacier in the canadian rocky mountains from a d 1673 to 1994 summer balance was reconstructed from tree ring estimates of summer temperature and precipitation in the canadian rockies winter balance was derived from tree ring data from sites bordering the gulf of alaska and in western british columbia the models for winter and summer balance each explain over 40 of the variance in the appropriate mass balance series over the period 1966 1994 the correlation between the reconstructed and measured net balances is 0 71 strong positive mass balances are reconstructed for 1695 1720 and 1810 1825 when higher winter precipitation coincided with reduced ablation periods of reconstructed positive mass balance precede construction of terminal moraines throughout the canadian rockies ca 1700 1725 and 1825 1850 positive mass balances in the period 1845 1880 also correspond to intervals of glacier readvance mass balances were generally negative between 1760 and 1805 from 1673 to 1883 the mean annual net balance was 70 mm water equivalent per year w e yr but it averaged 317 mm w e yr from 1884 to 1994 this reconstructed mass balance history provides a continuous record of glacier change that appears regionally representative and consistent with moraine and other proxy climate records

abrupt holocene climate transitions in the northern north atlantic region recorded by synchronized lacustrine records in iceland abstract two high sediment accumulation rate icelandic lakes the glacial lake hvitarvatn and the non glacial lake haukadalsvatn contain numerous tephra layers of known age which together with high resolution paleomagnetic secular variations allow synchronization with a well dated marine core from the shelf north of iceland a composite standardized climate record from the two lakes provides a single time series that efficiently integrates multi proxy data that reflect the evolution of summer temperatures through the holocene the first order trends in biogenic silica bsi 13c and c n rise relatively abruptly following deglaciation reaching maximum values shortly after 8 ka following a complex minimum between 8 7 and 8 0 ka the holocene thermal maximum htm in the lakes is marked by all proxies with a sharp transition out of the 8 ka cold event into peak summer warmth by 7 9 ka and continuing warm with some fluctuations until 5 5 ka decreasing summer insolation after the htm is reflected by incremental cooling initially 5 5 ka with subsequent cold perturbations recorded by all proxies 4 3 to 4 0 ka and 3 1 to 2 8 ka the strongest disturbance occurred after 2 ka with initial summer cooling occurring between 1 4 and 1 0 ka followed by a more severe drop in summer temperatures after 0 7 ka culminating between 0 5 and 0 2 ka following each late holocene cold departure bsi re equilibrated at a lower value independent of the sediment accumulation rate some of the abrupt shifts may be related to icelandic volcanism influencing catchment stability but the lack of a full recovery to pre existing values after the perturbation suggests increased periglacial activity decreased vegetation cover and glacier growth in the highlands of iceland the similarity in timing direction and magnitude of our multi proxy records from glacial and non glacial lakes and from the adjacent marine shelf suggests that our composite record reflects large scale shifts in ocean atmosphere circulation throughout the northern north atlantic

fluid flow compartmentalization in the sicilian fold and thrust belt implications for the regional aqueous fluid flow and oil migration history abstract the fluid flow history in the frontal part of the sicilian fold and thrust belt ftb has been reconstructed using an integrated structural petrographic geochemical and microthermometric approach the study focused on comparing fluid flow during progressive deformation along major thrust horizons and in pelagic sediments occurring in the associated thrust sheets foot and hanging wall a fluid flow model is constructed for the frontal part of the sicilian ftb syn deformational quartz and calcite have been precipitated along decollement horizons in the iudica scalpello study area the microthermometric analysis of fluid inclusions in the quartz and calcite indicated migration of low saline high temperature aqueous fluids 1 5 h the fluid flow history in the thrust sheets can be subdivided into two stages calcite of types 1 and 2 has identical light orange cathodoluminescence as the surrounding mudstone furthermore its isotope signature 2 13 c 18 o m h between 80 and 140 c type 3 calcite has less depleted 18 o values compared to calcite of types 1 and 2 and the 18 o from calcite in faults is even positive during the final stages of fluid flow with precipitation of calcite type 3 the fluid flow model invokes infiltration of overpressured fluids that migrated along the decollement zone these fluids only infiltrate the thrust sheet in the hanging wall of the thrust leading to a compartmentalized fluid flow pattern an identical fluid flow pattern with migration of low and hot saline fluids associated with hydrocarbons was observed in other parts of the sicilian fold and thrust belt with identical structural deformation and fluid flow patterns the study confirms the suitability of the frontal part of the sicilian fold and thrust belt as an outcrop analog for deeply submerged accretionary prisms the study thus offers unique insights in expected fluid flow patterns in thrust sheets of deeply submerged accretionary complexes

late holocene glacial activity in manatee valley southern coast mountains british columbia canada the dendroglaciologic and lichenometric research methodologies employed in this study provide a perspective of glaciological conditions from 5 ka to present in a remote headwater area of the british columbia coast mountains since holocene ice fronts of four glaciers at this site periodically extended below treeline previous glacier advances overrode and buried forests beneath till deposits this study suggests that glaciers were expanding into standing forests at 4 76 and 3 78 ka following glacier expansion at 3 78 ka a period of recession ensued when glaciers withdrew upvalley long enough for the development of deep pedogenic surfaces and the growth of trees exceeding 300 years investigations at beluga and manatee glaciers benchmark a subsequent episode of significant glacial expansion at 2 42 ka referred to as the manatee advance this advance has regional correlatives and is distinguished from the tiedemann advance at manatee glacier by documentation of substantive ice front retreat between the

modeling of fluid flow and pore pressure at the toe of oregon and barbados accretionary wedges fluid venting was recently found on the central oregon accretionary wedge and evidence of fluid flow along the decollement were obtained in the barbados wedge the chemistry of hydrocarbons contained in the migrating fluids is different in these two areas and indicates that the main source is deep for the barbados decollement and shallow for the oregon vents we apply a finite element model with imposed thrusting kinematics and nonlinearities in the compaction equation to the toe of both wedges no deep fluid source is included thus the main source is the footwall just below the frontal thrust the model indicates the following 1 pore pressure build up would be essentially controlled by kn the equivalent permeability in the direction normal to the strata in spite of very different sediment lithologies kn is of the order of 10 17 m2 for both oregon turbidites horath 1989 and barbados muds taylor and leonard 1990 and no high pore pressures can be obtained inside the offscraped sediments 2 permeability anisotropy greatly modifies fluid flow paths a fault with a permeability anisotropy of 103 would channel fluids efficiently but leave the footwall pressure almost unchanged a stratigraphic permeability anisotropy of 102 as documented for the oregon turbidites would redirect the flow of pressurized fluids in the footwall along strata into the trench if clogging of the frontal thrust occured fluids expelled from the footwall would move across the frontal thrust migrate along permeable strata in the hanging wall and then be vented near the top of the eroded anticline as observed in oregon 3 comparison of published estimates from data of fluid explusion fluxes with the modeling results suggests that a deeper and larger fluid source is needed at the barbados site but is not required for the oregon site

the little ice age glacier advance in the central andes 35 s argentina abstract this paper documents the occurrence of the little ice age lia in the el azufre and el penon glaciers at 35 s and in the las choicas and las damas glaciers at 34 55 s in the headwaters of the rio grande basin in the central andes of argentina moraine morphology stratigraphic relationships radiocarbon ages obtained from peat on these glacial deposits and the proximity to the active glaciers enabled us to reconstruct the lia advance in this area the lia maximum advance occurred between cal yr 1550 and 1720 ad and a readvance occurred around cal yr 1830 ad in addition glacier fluctuations of the las vacas and gussfeltd glaciers 33 s and el penon and el azufre glaciers were documented from the end of the 19th century to the present based on historical and aerial photographs and satellite images the glaciers showed a marked retreat during 1894 2007 minor readvances occurred in the 1980s and 1990s which could be related with strong warm enso events during these decades our results are consistent with observations made by other authors in the region

petrology of the bitumen manjak deposits of barbados hydrocarbon migration in an accretionary prism abstract bitumen manjak deposits in barbados are located particularly along fracture planes including faults and also in calcite veins as veinlets vug fillings and bedding parallel seams in sandstones and as matrix to diagenetic carbonates they occur particularly near the margins of the diapiric joes river formation and in immediately adjacent rocks reflecting the role of diapirism in the migration of hydrocarbon bearing fluids the larger bitumen veins trend between e w and ne sw following the strike of fault bounded packets of the accretionary prism the predominant fabric in the basal complex of barbados that is hydrocarbon migration followed the structural grain petrographic relationships of bitumen with chemosynthetic diagenetic carbonates suggest that hydrocarbon migration was a multi stage process the host sediments to the bitumens were not well consolidated and appear to have been in an overpressured state hydrocarbon generation may have contributed to overpressuring and buoyancy enhanced diapirism the association of bitumens with faults and decollement surfaces suggests that the lubricating action of the bitumen helped to accommodate deformation during diapirism and other processes related to the evolution of the accretionary prism widespread impregnation of sandstones in the joes river formation suggests that hydrocarbon migration was primarily by intergranular flow in a state of low confining pressure and did not depend on migration along the fault planes which may be of a later date

timing and climatic drivers for glaciation across semi arid western himalayan tibetan orogen abstract mapping and forty seven new 10 be ages help define the timing of glaciation in the ladakh and pangong ranges in northwest india five new local glacial stages are defined for the ladakh range from oldest to youngest these include the ladakh 4 glacial stage at 81 20 ka the ladakh 3 glacial stage not dated the ladakh 2 glacial stage at 22 3 ka the ladakh 1 glacial stage not dated and the ladakh cirque glacial stage at 1 8 0 4 ka three local glacial stages are defined for the pangong range which include the pangong 2 glacial stage at 85 15 ka the pangong 1 glacial stage at 40 3 ka and the pangong cirque glacial stage at 0 4 0 3 ka the new 10 be ages are combined with 645 recalculated 10 be ages from previous studies to develop the first regional framework of glaciation across the dryland regions of the greater himalaya transhimalaya pamir and tian shan at the western end of the himalayan tibetan orogen nineteen regional glacial stages are recognized that are termed semi arid western himalayan tibetan stages swhts these include swhts 9 at 311 32 ka swhts 7 at 234 44 ka tentative swhts 6 at 146 18 ka swhts 5e at 121 11 ka swhts 5a at 80 5 ka swhts 5a at 72 8 ka swhts 4 at 61 5 ka swhts 3 at 46 4 ka swhts 2f at 30 3 ka swhts 2e at 20 2 ka swhts 2d at 16 9 0 7 ka swhts 2c at 14 9 0 8 ka swhts 2b at 13 9 0 5 ka swhts 2a at 12 2 0 8 ka swhts 1e at 8 8 0 3 ka tentative swhts 1d at 6 9 0 2 ka tentative swhts 1c at 3 8 0 6 ka swhts 1b at 1 7 0 2 ka and swhts 1a at 0 4 0 1 ka regional glacial stages older than 21 ka are broadly correlated with strong monsoons swhts that are 21 ka or younger have smaller uncertainties and broadly correlate with global ice volume given by marine oxygen isotope stages and northern hemisphere climatic events oldest dryas older dryas younger dryas roman humid period and little ice age

a chronology of the little ice age in the tropical andes of bolivia 16 s and its implications for climate reconstruction dating moraines by lichenometry enabled us to reconstruct glacier recession in the bolivian andes since the little ice age maximum on the 15 proglacial margins studied we identified a system of ten principal moraines that marks the successive positions of glaciers over the last four centuries moraines were dated by performing statistical analysis of lichen measurements based on the extreme values theory like glaciers in many mid latitude mountain areas bolivian glaciers reached their maximal extent during the second half of the 17th century this glacier maximum coincides with the maunder minimum of solar irradiance by reconstructing the equilibrium line altitude and changes in mass balance we think the glacier maximum may be due to a 20 to 30 increase in precipitation and a 1 1 to 1 2 c decrease in temperature compared with present conditions in the early 18th century glaciers started to retreat at varying rates until the late 19th to early 20th century this trend was generally associated with decreasing accumulation rates by contrast glacier recession in the 20th century was mainly the consequence of an increase in temperature and humidity these results are consistent with observations made in the study region based on other proxies

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

anomalous glacier responses to 20th century climatic changes in darwin cordillera southern chile there is an asymmetric pattern response of glaciers in darwin cordillera 54 55 s 69 71 w to the climate of the 20th century this asymmetry is suggested here as a cause of an increased wind activity which has a pronounced orographic effect although climatic records for the last 50 years show a warming trend as well as no trend in precipitation in the area some glaciers are advancing the area is characterized by strong climatic gradients with high rates of precipitation on the southwestern side of the range and dry conditions on the northern side glaciers on the northern and eastern sides show a general trend of receding fronts with a few exceptions these glaciers have gradually and uninterruptedly been shrinking since the turn of the century on the southern rim the present extents of some glaciers are similar to their 20th century maximum extents these are in turn similar or close to the holocene maximum the most extreme sites are the glaciers on either side of mount darwin which is 2469 m high the north facing glacier ventisquero marinelli has retreated several hundred metres per year over the last two decades while the south facing glaciers in the pahia pia basin have advanced during the same period in this study the frontal changes over the last 50 years of 20 glaciers have been analysed aerial photographs verticals from 1943 and 1984 have been used as well as oblique aerial photographs from 1993 the general result is that glaciers with accumulation areas facing south and west show somewhat stable fronts while glaciers facing east and north show receding fronts

holocene glaciations in the ema glacier valley monte sarmiento massif tierra del fuego abstract investigations carried out in the ema glacier valley tierra del fuego on the eastern side of monte sarmiento massif enable the recognition of five holocene glacial events the oldest glacial advance deposited the so called external moraines of ema glacier with a probable occurrence between 6000 and 5000 14 c y bp without discarding the potential for these deposits to be from lateglacial time the remaining four readvances built up a complex inner moraine system named informally internal moraines of ema glacier the oldest recognized till unit that constitutes this proximal moraine system was deposited shortly before 3135 14 c y bp when glaciolacustrine sedimentation took place during glacier recession subsequent glacial advances accumulated till at about 1288 14 c y shortly after 695 14 c y and between 379 14 c y and 60 y bp this chronology of holocene glacier events coincides with and is well complemented by the one established by other authors for fiordo pia at cordillera darwin 75 km to the east the ema pia chronology is used to calibrate tentatively a series of moraine belts previously identified in the mountain ranges adjacent to ushuaia 150 km se of the surveyed region a comparative chart shows that the chronological data obtained for the neoglacial readvances in tierra del fuego are in accordance with those for the southern patagonian andes further north it follows that the holocene behavior of the glaciers in the andean region of tierra del fuego and southern patagonia is essentially a response to the same regional climate change

little ice age glacier fluctuations reconstructed for the southeastern tibetan plateau using tree rings long term records are essential for evaluating recent glacier fluctuation and its linkage to climate change moraines of two glaciers gawalong glacier and xincuo glacier in the southeastern tibetan plateau were dated germination date of the oldest tree yields a minimum age before 1760s for the outermost lateral moraine of gawalong glacier in southern bomi a tilted tree indicated that the glacier readvanced to its maximum position since the early 20th century at around 1987e1992 xincuo glacier in eastern gongbujiangda reached its little ice age lia maximum before 1876 the difference implies that detailed dating of moraines is necessary for studying lia glacier response to climate change in the study area trees growing on lia glacier deposits proved to be very useful for deriving age estimates of historic glacier fluctuations in the southeastern tibetan plateau

evolution of backarc rifting mariana trough 20 24 n the mariana trough is an actively opening backarc basin in the western pacific the trough formed by extension which longitudinally split an earlier arc massif creating a crescent shaped basin between the remnant west mariana ridge and eastern active volcanoes of the mariana arc opening increases southward from the volcano islands near 24 n where the two arcs join at 18 n in the central mariana trough the basin is widest and may be opening primarily by seafloor spreading we present a synthesis of closely spaced shipboard gravity magnetic and bathymetry measurements from the northern basin 20 24 n an area that undergoes a significant progressive southward increase in extension we have identified three stages in the evolution of rifting in this area 1 asymmetric rifting from 24 n to 22 15 n where faulting and magmatism have migrated laterally to remain near the active volcanic arc side of the basin 2 a localization of rifting from 22 15 n to 21 n where the primary zone of rifting separates from the active volcanic arc and 3 a further concentration of rifting from 21 n to 20 n leading to the formation of deep tectonic grabens near the center of the basin this last stage may be a precursor to or incipient seafloor spreading we describe a new type of magnetic lineation resolved in a three dimensional seafloor magnetization inversion of the trough between 20 and 24 n the detailed character of these lineations their association with tectonic structures and other geophysical observations indicate that they are not seafloor spreading lineations but rather result from magnetic intrusions and volcanism emplaced within preexisting less magnetic rifted arc crust the development of these well defined magnetization bands indicates that the zone of magmatism remains relatively narrow at any one time throughout the opening of the trough although tectonic deformation appears to be more widely distributed in addition the geometry of the magnetization bands with respect to the remnant arc border faults indicates that rifting propagated rapidly northward

an advance of soler glacier north patagonian icefield at c ad 1222 1342 soler glacier is a temperate outlet glacier on the eastern side of the north patagonian icee eld in chile the glacier is currently receding from its little ice age maximum position attained sometime between ad 1600 and 1900 across the snout and foree eld of the glacier is an arcuate belt of well sorted granule gravel and coarse sand containing tree remains these sediments are interpreted as reworked glaciolacustrine material elevated to the glacier surface by thrusting and folding radiocarbon dating of samples of tree remains in these reworked glaciolacustrine sediments demonstrates that the glacier overrode this lake bed sometime between ad 904 and ad 1334 in situ tree remains plastered onto a large boulder in front of the glacier constrain this advance to the period between ad 1222 and ad 1342 this advance precedes by several hundred years the maximum little ice age extent of other north patagonian icee eld outlet glaciers suggesting either an early age for the onset of little ice age conditions or a previously unrecognized period of glacier advance prior to the advance at c ad 1222 to ad 1342 soler glacier was more recessed than at present cone rming the dynamic response of patagonian glaciers to holocene climatic e uctuations

two millennia of glacier advances from southern iceland dated by tephrochronology two glaciers at eyjafjallajokull south iceland provide a record of multiple episodes of glacier advance since the sub atlantic period ca 2000 yr ago a combination of tephrochronology and lichenometry was applied to date ice marginal moraines tills and meltwater deposits two glacier advances occurred before the 3rd century ad others in the 9th and 12th centuries bracketing the medieval warm period and five groups of advances occurred between ad 1700 and 1930 within the little ice age the advances of eyjafjallajokull before the norse settlement ca ad 870 were synchronous with other glacier advances identified in iceland in contrast medieval glacier advances between the 9th and 13th centuries are firmly identified for the first time in iceland this challenges the view of a prolonged medieval warm period and supports fragmentary historical data that indicate significant medieval episodes of cooler and wetter conditions in iceland an extended and more detailed glacier chronology of the mid and late little ice age is established which demonstrates that some small outlet glaciers achieved their little ice age maxima around ad 1700 while little ice age advances across iceland appear to synchronous the timing of the maximum differs between glacier type and region

late holocene glacial history of scimitar glacier mt waddington area british columbia coast mountains canada scimitar glacier originates below the northeast face of mt waddington in the southern british columbia coast mountains and flows 18 km down valley to calve into a proglacial lake at several locations downwasting of the glacier surface has exposed stacked till units separated by wood bearing horizons in the proximal slopes of lateral moraines flanking the glacier historical moraine collapse and erosional breaching has also revealed the remains of standing trees buried in moraine dammed lake sediments radiocarbon and tree ring dating show that scimitar glacier expanded down valley at least three times in the late holocene the earliest evidence found for ice expansion indicates scimitar glacier was advancing in 3167 2737 cal years bp in association with the regional tiedemann advance following this advance the glacier downwasted prior to expanding in 1568 1412 cal years bp during the first millennial advance a final period phase of moraine construction was initiated during late little ice age glacia

holocene evolution of the western greenland ice sheet assessing geophysical ice sheet models with geological reconstructions of ice margin change abstract geophysical ice sheet models are used to predict future ice sheet dimensions and in turn these projections help estimate the magnitude of eustatic sea level rise before models can confidently predict ice sheet behavior they must be validated by being able to duplicate the geological record of ice sheet change here we review geological records of greenland ice sheet gris change with emphasis on the warmer than present middle holocene and compare these records to published studies that numerically simulate gris behavior through the holocene geological records are concentrated in west and southwest greenland which are also the regions where the gris margin likely experienced the greatest distance of inland retreat during the middle holocene several records spanning from melville bugt to jakobshavn isfjord in western greenland indicate the gris achieved its minimum extent between 5 and 3 ka and farther south in the kangerlussuaq region new data presented here indicate the ice margin reached its minimum extent between 4 2 and 1 8 ka in the narsarsuaq region in southern greenland the gris likely achieved its minimum configuration between 7 and 4 ka we highlight key similarities and discrepancies between these reconstructions and model results and finally we suggest that despite some degree of inland retreat the west and southwest gris margin remained relatively stable and close to its current position through the holocene thermal maximum

10be ages of late pleistocene deglaciation and neoglaciation in the north central brooks range arctic alaska we present a chronology of late pleistocene deglaciation and neoglaciation for two valleys in the north central brooks range alaska using cosmogenic 10be exposure dating the two valleys show evidence of ice retreat from the northern range front before 16 15 ka and into individual cirques by 14 ka there is no evidence for a standstill or re advance during the lateglacial period indicating that a glacier advance during the younger dryas if any was less extensive than during the neoglaciation the maximum glacier expansion during the neoglacial is delimited by moraines in two cirques separated by about 200 km and dated to 4 6 0 5 and 2 7 0 2 cal ka bp both moraine ages agree with previously published lichen inferred ages and confirm that glaciers in the brooks range experienced multiple advances of similar magnitude throughout the late holocene the similar extent of glaciers during the middle holocene and the little ice age may imply that the effect of decreasing summer insolation was surpassed by increasing aridity to limit glacier growth as neoglaciation progressed copyright 2012 john wiley sons ltd

historical fluctuations of the gualas and reicher glaciers north patagonian icefield chile dendrochronology was used to date historical fluctuations of the little visited gualas and reicher glaciers on the north patagonian icefield in southern chile vegetation trimlines dating to ad 1876 1909 and 1954 show that glacier downwasting and retreat mirrored the patterns found at the neighbouring san rafael and san quintin glaciers intermediate stages of recession of the gualas and reicher glaciers dating to the early 1920s mid 1930s and 1960s are also reflected by similar stages in the san rafael and san quintin glaciers we propose that the common responses shown by these four glaciers argue for climatic control of their movements and that glacier dynamics in this region are principally controlled by changes in precipitation rather than temperature since annual mean temperatures at cabo raper the nearest meteorological station have shown no trend since the early 1940s whereas precipitation peaking in the winter months has varied widely since the 1920s

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

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

holocene glacier fluctuations in alaska abstract this review summarizes forefield and lacustrine records of glacier fluctuations in alaska during the holocene following retreat from latest pleistocene advances valley glaciers with land based termini were in retracted positions during the early to middle holocene neoglaciation began in some areas by 4 0 ka and major advances were underway by 3 0 ka with perhaps two distinct early neoglacial expansions centered respectively on 3 3 2 9 and 2 2 2 0 ka tree ring cross dates of glacially killed trees at two termini in southern alaska show a major advance in the ad 550s 720s the subsequent little ice age lia expansion was underway in the ad 1180s 1320s and culminated with two advance phases respectively in the 1540s 1710s and in the 1810s 1880s the lia advance was the largest holocene expansion in southern alaska although older late holocene moraines are preserved on many forefields in northern and interior alaska tidewater glaciers around the rim of the gulf of alaska have made major advances throughout the holocene expansions were often asynchronous with neighboring termini and spanned both warm and cool intervals suggesting that non climatic factors were important in forcing these advances however climatic warming appears to have initiated most rapid iceberg calving retreats large glaciers terminating on the forelands around the gulf of alaska may have had tidewater termini early in the holocene but have progressively become isolated from the adjacent ocean by the accumulation and subaerial exposure of their own sediments

holocene and latest pleistocene fluctuations of stutfield glacier canadian rockies the holocene and late glacial history of fluctuations of stutfield glacier are reconstructed using moraine stratigraphy tephrochronology and dendroglaciology stratigraphic sections in the lateral moraines contain tills from at least three glacier advances separated by volcanic tephras and paleosols the oldest pre mazama till is correlated with the crowfoot advance dated elsewhere to be younger dryas equivalent a neoglacial till is found between the mazama tephra and a paleosol developed on the bridge river tephra a log dating 2400 bp from the upper part of this till indicates that this glacier advance correlated with the peyto advance culminated shortly before deposition of the bridge river tephra radiocarbon and tree ring dates from overridden trees exposed in moraine sections indicate that the initial cavell little ice age lia advance overrode this paleosol and trees after a d 1271 three subsequent phases of the cavell advance were dated by dendrochronology the maximum glacier extent occurred in the mid 18th century predating 1743 on the southern lateral although ice still occupied and tilted a tree on the north lateral in 1758 subsequent glacier advances occurred ca 1800 1816 and in the late 19th century the relative extent of the lia advances at stutfield differs from that of other major eastward flowing outlets of the columbia icefield which have maxima in the mid late 19th century this is the first study from the canadian rockies to demonstrate that the large morphologically simple lateral moraines defining the lia glacier limits are actually composite features built up pro gressively but discontinuously over the holocene and contain evidence of multiple holocene and crowfoot age gla cier advances resume la stratigraphie des moraines la tephrochronologie et la dendroglaciologie des moraines ont servi a recons truire les fluctuations a l holocene et au cours de l histoire glaciaire tardive du glacier stutfield les sections stratigra phiques dans les moraines laterales contiennent des tills d au moins trois avancees glaciaires separees par des tephras volcaniques et des paleosols le plus ancien le till pre mazama est correle a l avancee crowfoot dont on a determine l ge ailleurs comme etant un equivalent du dryas recent un till de l epoque neo glaciaire se retrouve entre le tephra mazama et un paleosol developpe sur le tephra de bridge river un billot date 2400 bp provenant de la partie supe rieure de ce till indique que cette avancee glaciaire correlee a l avancee de peyto a culmine peu de temps avant la deposition du tephra de bridge river des datations au 14 c et des series chronlogiques provenant d arbres recouverts puis exposes dans des sections de moraine indiquent que l avancee cavell initiale petit ge glaciaire a chevauche ce paleosol et les arbres apres l an 1271 la dendrochronologie a permis la datation de trois phases subsequentes de l avancee cavell l etendue glaciaire maximale eut lieu au milieu du 18e siecle avant 1743 sur le cote sud bien que la glace fut encore presente sur le cote nord et y ait bascule un arbre en 1758 des avancees glaciaires subsequentes ont eu lieu vers 1800 1816 et vers la fin du 19e siecle l etendue relative des avancees du petit ge glaciaire a stutfield differe de celles d autres glaciers majeurs du champ de glace columbia s ecoulant vers l est et qui ont eu leur maxi mum dans la deuxieme moitie du 19e siecle cette etude est la premiere provenant des rocheuses canadiennes a de monter que les grandes moraines laterales morphologiquement simples definissant les limites du glacier au petit ge glaciaire sont en fait des elements composites developpes progressivement mais de facon discontinue tout au cours de l holocene et qu elles contiennent des evidences d avancees glaciaires multiples d ge holocene et crowfoot

holocene glacier history of the lago argentino basin southern patagonian icefield abstract we present new geomorphic stratigraphic and chronologic data for holocene glacier fluctuations in the lago argentino basin on the eastern side of the southern patagonian andes chronologic control is based on 14c and surface exposure 10be dating after the lateglacial maximum at 13 000 cal yrs bp the large ice lobes that filled the eastern reaches of lago argentino retreated and separated into individual outlet glaciers this recession was interrupted only by a stillstand or minor readvance at 12 200 cal yrs bp the eight largest of these individual outlet glaciers are from north to south upsala agassiz onelli spegazzini mayo ameghino perito moreno and grande formerly frias holocene recession of upsala glacier exposed brazo cristina more than 10 115 100 cal yrs bp and reached inboard of the holocene moraines in agassiz este valley by 9205 85 cal yrs bp ice remained in an inboard position until 7730 50 cal yrs bp several subsequent glacier readvances are well documented for the upsala and frias glaciers the upsala glacier readvanced at least seven times the first being a relatively minor expansion documented only in stratigraphic sections between 7730 50 and 7210 45 cal yrs bp the most extensive holocene advances of upsala glacier resulted in the deposition of the pearson 1 moraines and related landforms which are divided into three systems the pearson 1a advance occurred about 6000 5000 cal yrs bp and was followed by the slightly less extensive pearson 1b and 1c advances dated to 2500 2000 and 1500 1100 cal yrs bp respectively subsequent advances of upsala glacier resulted in deposition of the pearson 2 moraines and corresponding landforms also separated into three systems pearson 2a 2b and 2c constructed respectively at 700 400 and

detailed structure and possible fluid paths at the toe of the barbados accretionary wedge odp leg 110 area during the summer of 1987 a bottom navigated heat flow and deep tow side scan sonar survey was carried out over the toe of the barbados accretionary wedge in the ocean drilling program odp leg 110 drilling area surface traces of the leg 110 drill holes were recognized on the sonar images precise relocation of the odp holes relative to a reference multichannel seismic line led to a new interpretation of some of the structures previously described by the leg 110 scientific party for example one thrust formerly interpreted as a forward propagating major thrust is interpreted here as a near surface backthrust developed above a probable shallow decollement located at the base of the pleistocene sequence we use these new structural data as surface guidelines in building a balanced cross section of and defining a fluid flow pattern within the toe of the wedge using new closely spaced heat flow data we discuss briefly the fluid flow along the major fractures through the wedge

a new approach to calculating holocene winter precipitation by combining glacier equilibrium line altitudes and pine tree limits a case stud from hardangerjokulen central southern norway at hardangerjokulen central southern norway detailed knowledge of the number age and magnitude of holocene glacier fluctuations is used to reconstruct variations in equilibrium line altitude ela for the last 10 000 years present and past elas are based on an accumulation area ratio aar of 0 7 and are adjusted for land uplift a synchronous relationship between advanced glacier positions and the highest pine tree limits pinus sylvestris l is demonstrated for the early to mid holocene in southern scandinavia which indicates that warm summers were compensated for by high winter precipitation based on pine tree limit fluctuations as a measure of mean ablation season temperature holocene variations in winter precipitation at hardangerjokulen have been calculated by substitution in the close exponential relationship between mean ablation season temperature and winter precipitation at the ela of norwegian glaciers setting the winter precipitation during the period ad 1961 1990 at 100 mean values

sediment accumulation rates in subpolar fjords impact of post little ice age glaciers retreat billefjorden svalbard abstract the little ice age 1600 1900 ad and 20th century sediment accumulation rates in billefjorden a subpolar fjord on svalbard were reconstructed by applying 210 pb 137 cs and ams 14 c datings the modern sediment accumulation rate decreases from more than 0 39 cm y 1 at the fjord head to 0 08 cm y 1 close to the fjord mouth however during the little ice age the sediments accumulated at a much lower rate of 0 02 cm y 1 in the central fjord basin this difference is most likely related to the rapid retreat of glaciers during the 20th century when most of them withdrew up to 2 km the post little ice age increases in temperature and a negative glacier mass balance resulted in a larger meltwater discharge transferring substantial amounts of sediments released from the glaciers as well as those eroded from previously stored unconsolidated glacial sediments a comparison of data from the subpolar fjords of svalbard suggests that the increase in the sediment accumulation rate is a common trend and further increases might be expected if climate warming continues the properties of the fjord sediments grain size ird coarse fraction composition clay mineralogy from the little ice age and the 20th century showed no distinct differences the change in the accumulation rate may be the most evident sedimentary record of this climatic change

holocene climate variability and periodicities in south central sweden as interpreted from peat humification analysis analysis of the decomposition of peat has been used to identify climatic shifts over the last 10 000 years in two raised bogs stomyren and kortlandamossen south central sweden age depth curves have been constructed using radiocarbon dates and tephra layers peat humification data have been subjected to spectral analyses using the lomb scargle fourier method and reveal a periodicity of c 250 years in both records cycles of c 200 yr and c 400 yr were found at stomyren and at kortlandamossen respectively these periodicities could correspond to changes in solar activity levels a test estimating the possible level of noise has been applied to the spectral analyses the humification indices indicate prominent shifts to wetter conditions at c 7500 4300 4200 3700 3500 and 2800 2400 cal yr bp the most distinct drier phases start at c 4500 and 3250 cal yr bp

tectonic context of fluid venting at the toe of the eastern nankai accretionary prism evidence for a shallow detachment fault during the kaiko nankai diving cruise the peak of the venting activity was located near the top of the very first anticline the most prominent morphological feature between the mid slope 3870 m and the apex of the fold 3770 m is a 20 m high cliff cutting through subhorizontal massive mudstones affected by numerous joints the trend of this scarp is oblique to the fold axis and structurally controlled along two sharply defined nne sse and e w directions fresh talus and blocks found locally suggest active tectonics and recent erosion intense deformation is evident from strongly tilted strata restricted to the base of the cliff that we interpret as an upslope thrust at the scale of seabeam mapping this thrust can be followed eastward for more than 5 km along the 3820 m isobath two seismic lines recorded during one of the pre site surveys show deformation at shallow depth including small scale folding and thrusting affecting only the wedge shaped top sequence deeper layers can be traced continuously below this sequence we conclude that the boundary between the piggy back basin and the frontal fold turbidites acts as a shallow detachment fault and interpret the base of the cliff as the outcrop of the fault dense colonies ofcalyptogena clams and strongly nonlinear thermal gradients locate the major peak of fluid activity at the edge of the plateau above the main cliff scattered biological colonies as well as white bacterial mats and cemented chimneys were also found in a narrow belt along the base of the cliff fluid activity is thus closely related to the shallow detachment fault fluid being expelled both at the outcrop of the fault and above it through the overlying strata possibly using the very dense joint network

a new approach for reconstructing glacier variability based on lake sediments recording input from more than one glacier abstract we explore the possibility of building a continuous glacier reconstruction by analyzing the integrated sedimentary response of a large 440 km2 glacierized catchment in western norway as recorded in the downstream lake nerfloen n61 56 e6 52 a multi proxy numerical analysis demonstrates that it is possible to distinguish a glacier component in the 8000 yr long record based on distinct changes in grain size geochemistry and magnetic composition principal component analysis pca reveals a strong common signal in the 15 investigated sedimentary parameters with the first principal component explaining 77 of the total variability this signal is interpreted to reflect glacier activity in the upstream catchment an interpretation that is independently tested through a mineral magnetic provenance analysis of catchment samples minimum glacier input is indicated between 6700 5700 cal yr bp probably reflecting a situation when most glaciers in the catchment had melted away whereas the highest glacier activity is observed around 600 and 200 cal yr bp during the local neoglacial interval 4200 cal yr bp until present five individual periods of significantly reduced glacier extent are identified at 3400 3000 2700 2100 2000 1700 1500 and 900 cal yr bp

holocene palaeoclimatic reconstruction in northern iceland approaches and results abstract the period since the mid 19th century when instrumental meteorological recording first started in iceland has shown climate conditions close to or even at both holocene minimum and optimum levels the 19th century part of the little ice age represents a thermal minimum whilst the warmest decades of the 20th century are close to the estimated holocene thermal maximum a model describing sea ice climate ela relationships in northern iceland for this period has been developed providing a calibrated proxy climate record as a basis for palaeoclimatic reconstruction for the holocene as a whole glacier advances in the periods around 4700 bp around 4200 bp ca 3200 3000 bp around 2000 bp around 1500 bp and around 1000 bp based on radiocarbon dating and tephrochronology mark climatic minima of the post preboreal holocene when conditions were comparable to the extremes in the second half of the 19th century compared to optimal holocene thermal conditions with temperatures at least as high as in the 1930s the range of holocene temperature variation was ca 3 k this was accompanied by a doubling in precipitation from the thermal minima to the maxima

heat flow tectonics and fluid circulation at the toe of the barbados ridge accretionary prism detailed patterns of near surface tectonics and heat flow were investigated at two locations at the toe of the barbados ridge accretionary prism at the two locations in the thickly sedimented southern portion of the prism near 12 20 n and in the northern area drilled during ocean drilling program odp leg 110 near 15 32 n relative highs of heat flow were associated with zones of thrusting we attribute them to upward advection of water rising from the decollement along faults through the sediments in the odp area a significant heating plate effect from warm fluids flowing along the decollement and thrusts is required to account for the high regional heat flow this effect implies high rates of fluid flow at the decollement which can only be non steady state or would require massive lateral transport of fluids along strike

holocene glacier history of bjornbreen and climatic reconstruction in central jotunheimen norway based on proximal glaciofluvial stream bank mires abstract holocene variations of bjornbreen smorstabbtinden massif west central jotunheimen are reconstructed from the lithostratigraphy of two alpine stream bank mires flooded episodically by meltwater the approach uses multiple sedimentological indicators weight loss on ignition mean grain size grain size fractions bulk density moisture content and magnetic susceptibility an a priori model of overbank deposition of suspended glaciofluvial sediments a detailed chronology based on 56 radiocarbon dates and a little ice age sedimentological analogue rapid late preboreal deglaciation was indicated by immigration of betula pubescens by 9700 cal bp an interval of at least 3000 years in the early holocene when glaciers were absent was interrupted by two abrupt episodes of glacier expansion around the time of the finse event the first at ca 8270 7900 cal bp bjornbreen i event and the second at ca 7770 7540 cal bp bjornbreen ii event neoglaciation began shortly before ca 5730 cal bp with gradual build up to the maximum of the bjornbreen iii event at ca 4420 cal bp later maxima occurred at ca 2750 cal bp bjornbreen iv event and at 1300 1260 1060 and 790 cal bp all within the bjornbreen v event glaciers were smaller than today and possibly melted away on several occasions in the late holocene ca 3950 1410 and 750 cal bp minor maxima also occurred at ca 660 and 540 cal bp within the late mediaeval warm period and the early little ice age respectively the little ice age maximum was dated to 213 25 bp ca 205 cal bp the relative magnitudes of the main glacier maxima were determined erdalen event little ice age event bjornbreen vi bjornbreen i finse event bjornbreen ii bjornbreen v bjornbreen iv bjornbreen iii these episodic events of varying magnitude and abruptness were used in conjunction with an independent summer temperature proxy to reconstruct variations in equilibrium line altitude ela and a holocene record of winter precipitation since the preboreal ela varied within a range of about 390 m and winter precipitation ranged between 40 and 160 of modern values winter precipitation variations appear to have been the main cause of these century to millennial scale holocene glacier variations

holocene moraine chronology spitsbergen svalbard lichenometric evidence for multiple neoglacial advances in the arctic late holocene neoglacial moraines occurring within 1 or 2 km of present glacier margins are prominent features in the forefields of spitsbergen glaciers little ice age moraines are typically the most extensive and best preserved moraines of older holocene advances are much less common where observed older moraines occur as moraine remnants and provide irrefutable evidence of earlier neoglacial advances the fragmentary moraine record indicates two little ice age advances and two older neoglacial advances lichenometry provides calibrated ages for periods of moraine stabilization the oldest moraines stabilized by ca 1500 years ago and a second group of moraines stabilized by ca 1000 years ago little ice age moraines were deposited during two periods an early group of moraines stabilized ca 650 years ago and a later group during the last several centuries the proposed moraine chronology compares well with other proxy climate records on spitsbergen and with moraine records from areas borde

a 3000 year varved record of glacier activity and climate change from the proglacial lake hvitarvatn iceland a suite of environmental proxies in annually laminated sediments from hvitarvatn a proglacial lake in the central highlands of iceland are used to reconstruct regional climate variability and glacial activity for the past 3000 years sedimentological analysis is supported by tephrostratigraphy to confirm the continuous annual nature of the laminae and a master varve chronology places proxies from multiple lake cores in a secure geochronology varve thickness is controlled by the rate of glacial erosion and efficiency of subglacial discharge from the adjacent langjokull ice cap the continuous presence of glacially derived clastic varves in the sediment fill confirms that the ice cap has occupied the lake catchment for the duration of the record varve thickness varve thickness variance ice rafted debris total organic carbon mass flux and bulk concentration and c n of sedimentary organic matter reveal a dynamic late holocene climate with abrupt and large scale changes in ice cap size and landscape stability a first order trend toward cooler summers and ice cap expansion is punctuated by notable periods of rapid ice cap growth and or landscape instability at ca 1000 bc 600 bc 550 ad and 1250 ad the largest perturbation began ca 1250 ad signaling the onset of the little ice age and the termination of three centuries of relative warmth during medieval times consistent deposition of ice rafted debris in hvitarvatn is restricted to the last 250 years demonstrating that langjokull only advanced into hvitarvatn during the coldest centuries of the little ice age beginning in the mid eighteenth century this advance represents the glacial maximum for at least the last 3 ka and likely since regional deglaciation 10 ka the multi centennial response of biological proxies to the hekla 3 tephra deposition illustrates the significant impact of large explosive eruptions on local environments and catchment sensitivity to perturbations

glacier fluctuations during the past 2000 years abstract a global compilation of glacier advances and retreats for the past two millennia grouped by 17 regions excluding antarctica highlights the nature of glacier fluctuations during the late holocene the dataset includes 275 time series of glacier fluctuations based on historical tree ring lake sediment radiocarbon and terrestrial cosmogenic nuclide data the most detailed and reliable series for individual glaciers and regional compilations are compared with summer temperature and when available winter precipitation reconstructions the most important parameters for glacier mass balance in many cases major glacier advances correlate with multi decadal periods of decreased summer temperature in a few cases such as in arctic alaska and western canada some glacier advances occurred during relatively warm wet times the timing and scale of glacier fluctuations over the past two millennia varies greatly from region to region however the number of glacier advances shows a clear pattern for the high mid and low latitudes and hence points to common forcing factors acting at the global scale globally during the first millennium ce glaciers were smaller than between the advances in 13th to early 20th centuries ce the precise extent of glacier retreat in the first millennium is not well defined however the most conservative estimates indicate that during the 1st and 2nd centuries in some regions glaciers were smaller than at the end of 20th early 21st centuries other periods of glacier retreat are identified regionally during the 5th and 8th centuries in the european alps in the 3rd 6th and 9th centuries in norway during the 10th 13th centuries in southern alaska and in the 18th century in spitsbergen however no single period of common global glacier retreat of centennial duration except for the past century has yet been identified in contrast the view that the little ice age was a period of global glacier expansion beginning in the 13th century or earlier and reaching a maximum in 17th 19th centuries is supported by our data the pattern of glacier variations in the past two millennia corresponds with cooling in reconstructed temperature records at the continental and hemispheric scales the number of glacier advances also broadly matches periods showing high volcanic activity and low solar irradiance over the past two millennia although the resolution of most glacier chronologies is not enough for robust statistical correlations glacier retreat in the past 100 150 years corresponds to the anthropogenic global temperature increase many questions concerning the relative strength of forcing factors that drove glacier variations in the past 2 ka still remain

holocene fluctuations of a polythermal glacier in high alpine eastern jotunheimen central southern norway abstract bukkehammarbreen is a polythermal cirque glacier lying in the permafrost zone of eastern jotunheimen central southern norway in the proglacial lake bukkehammartjorna sediment analyses of loss on ignition loi magnetic susceptibility and analyses of grain size distribution have been used to reconstruct holocene variations in glacier activity and other catchment processes the glacier has low sediment production hence a low signal to noise ratio of minerogenic sediment flux is found grain size analyses are used to enhance the glacigenic signal and to detect glacier variations and other changes in sediment input the sedimentological record from bukkehammartjorn is compared with three other lake records from the same region in order to separate the glacial signal from variations in organic production and episodes of enhanced non glacial minerogenic sedimentation subsequent to the deglaciation after the younger dryas a preboreal glacial advance culminated before 10 100 cal bp this was followed by a prolonged period with no glaciers in the catchment until 7500 cal bp after which there is evidence of limited glacier activity lasting until 6800 cal bp between 6700 and 6000 cal bp the catchment was deglaciated after 6000 cal bp bukkehammarbreen reformed increasing in size towards 3800 cal bp with evidence for reduced glacier activity around 5200 cal bp a glacier with approximately similar size as at present has existed after 3800 cal bp the investigation has demonstrated the usefulness of multi site and multi parameter lacustrine investigations in reconstructing glacier fluctuations and for testing and validating the results the investigations have shown that grain size variations in sediment cores located at increasing distance from the meltwater inlet of a lake may provide an indicator of paraglacial activity in the catchment during the holocene the results also suggest that the lower altitudinal limit of permafrost in eastern jotunheimen remained below about 1800 m during the holocene

late holocene temperature fluctuations on the tibetan plateau abstract proxy data of palaeoclimate like ice cores tree rings and lake sediments document aspects of climate changes on the tibetan plateau during the last 2000 years the results show that the tibetan plateau experienced climatic episodes such as the warm intervals during ad 800 1100 and 1150 1400 the little ice age between ad 1400 and 1900 and an earlier cold period between the 4th and 6th centuries in addition temperatures varied from region to region across the plateau a warm period from ad 800 to 1100 in the northeastern tibetan plateau was contemporaneous with cooling in the southern tibetan plateau which experienced warming between ad 1150 and 1400 large scale trends in the temperature history from the northeastern tibetan plateau resemble those in eastern china more than the trends from the southern plateau the most notable similarities between the temperature variations of the tibetan plateau and eastern china are cold phases during ad 1100 1150 1500 1550 1650 1700 and 1800 1850

continental margin tectonics forearc processes recent studies of convergent plate margins and the structural development of forearc terranes are summarized in a critical review of u s research from the period 1987 1990 topics addressed include the geometry of accretionary prisms coulomb wedge taper and vertical motion in response to tectonic processes offscraping vs underplating or subduction the response to oblique convergence fluids in forearc settings the thermal framework and the effects of fluid advection and serpentinite seamounts also included is a comprehensive bibliography for the period

holocene glacier variations in central jotunheimen southern norway based on distal glaciolacustrine sediment cores abstract sediment cores from two glacier fed lakes are used to reconstruct a continuous record of glacier variations since about 10 000 cal bp in the smorstabbtinden massif of central jotunheimen southern norway particular attention is paid to the century to millennial scale pre little ice age glacial signal based on an estimated temporal resolution of 55 and 25 yr cm 1 for bovertunsvatnet and dalsvatnet respectively visible lithostratigraphic variations organic content loss on ignition calcium carbonate content magnetic susceptibility and grain size fractions especially the fine silt are used as proxy indicators of glacier presence and extent in the lake catchments following deglaciation the early holocene was characterized by generally small glaciers until a major advance the finse event peaking at approximately 8200 cal bp from 7900 to at least 5300 cal bp glaciers appear to have been absent from central jotunheimen there is evidence of glacier expansion between about 2400 and 1600 cal bp the bovertun i event and between about 1400 and 800 cal bp the bovertun ii event before reduced glacier extent during the mediaeval warm period finally the most extensive neoglacial maximum occurred during the little ice age after 500 cal bp in addition to providing a record of the broad pattern of climatically forced holocene glacier variations periodicities at 110 140 200 285 and about 500 yr have been identified uncertainties remain concerning the precise timing of events glacierization and deglacierization detection thresholds a possible mid to late holocene 5300 2500 cal bp neoglacial build up of small glaciers and shorter term decadal to century scale variations in glacier size for which more proximal sites are required

holocene and latest pleistocene climate and glacier fluctuations in iceland abstract multiproxy climate records from iceland document complex changes in terrestrial climate and glacier fluctuations through the holocene revealing some coherent patterns of change as well as significant spatial variability most studies on the last glacial maximum and subsequent deglaciation reveal a dynamic iceland ice sheet iis that responded abruptly to changes in ocean currents and sea level the iis broke up catastrophically around 15 ka as the polar front migrated northward and sea level rose indications of regional advance or halt of the glaciers are seen in late allerod early younger dryas time and again in preboreal time due to the apparent rise of relative sea level in iceland during this time most sites contain evidence for fluctuating tidewater glacier termini occupying paleo fjords and bays the time between the end of the younger dryas and the preboreal was characterized by repeated jokulhlaups that eroded glacial deposits by 10 3 ka the main ice sheet was in rapid retreat across the highlands of iceland the holocene thermal maximum htm was reached after 8 ka with land temperatures estimated to be 3 c higher than the 1961 1990 reference and net precipitation similar to modern such temperatures imply largely ice free conditions across iceland in the early to mid holocene several marine and lacustrine sediment climate proxies record substantial summer temperature depression between 8 5 and 8 ka but no moraines have been detected from that time termination of the htm and onset of neoglacial cooling took place sometime after 6 ka with increased glacier activity between 4 5 and 4 0 ka intensifying between 3 0 and 2 5 ka although a distinct warming during the medieval warm period is not dramatically apparent in icelandic records the interval from ca ad 0 to 1200 is commonly characterized by relative stability with slow rates of change the literature most commonly describes little ice age moraines ca ad 1250 1900 as representing the most extensive ice margins since early holocene deglaciation with temperature depressions of 1 2 c compared to the ad 1961 1990 average steep north south and west east temperature gradients are reconstructed in the holocene records of iceland suggesting a strong maritime influence on the terrestrial climate of iceland

timing and significance of mid holocene glacier advances in northern and central iceland tephrochronology is used to date mid holocene moraines in iceland in the granavatn cirque trollaskagi peninsula the h 4 tephra ca 3830 yr bp lies within sediment accumulated against the distal slope of a lateral moraine providing a minimum age for glaciation and the absence of h 5 ca 5950 yr bp provides a maximum age by implication the cirque was glaciated in the early neoglacial period a large rock glacier the development of which post dates the moraine probably formed within the little ice age lia of the sixteenth to nineteenth centuries ad at eystri lo mundarjokull in central iceland frozen colluvium containing the h 3 ca 2900 yr bp and h 4 tephras provides a minimum age of ca 3830 yr bp for two terminal moraines and a maximum age of ca 2900 yr bp for a third the older moraines are correlated with the vatnsdalur i drangagil advances ca 4700 yr bp and 4500 yr bp respectively and the begisardalur i advance ca 4200 yr bp they imply that early neoglacial advances throughout iceland were locally more extensive than those of the lia the apparent lia holocene glacial maximum may reflect i selective sampling of large ice cap outlet glaciers where the preservation potential of pre lia deposits is low and ii reliance on lichenometric dating which has a restriced temporal range copyright 2001 john wiley sons ltd

little ice age fluctuations of small glaciers in the monte fitz roy and lago del desierto areas south patagonian andes argentina abstract current knowledge about late holocene glacier fluctuations in the south patagonian andes is mainly based on evidence from large outlet glaciers of the north and south patagonian icefields and few data exist for the smaller glaciers elsewhere in the region here we provide dendrogeomorphological evidence for little ice age lia and post lia activity for five small glaciers near the northeast margin of the south patagonian icefield the study sites include glaciar torre and piedras blancas in the monte fitz roy area and three adjacent glaciers near lago del desierto at these sites the lia maximum position was identified by massive moraines with mature trees dating to the late 1500s early 1600s several older moraines were observed beyond these limits but could not be precisely dated relatively synchronous advances occurred at most glaciers in the early 1700s and were dated using living trees and in situ subfossil material all glaciers show three to five subsequent advances mostly concentrated between the mid 19th and early 20th centuries estimates based on landsat tm imagery indicate these glaciers lost between 15 and 46 of their lia areas by 1984 and a further 5 18 by 2005 with the smallest glaciers showing the greatest proportional loss paired comparisons of contemporary and the earliest known photography for the glaciers in the fitz roy area confirm this mass loss these results provide important new information on the glacier history of this area but additional more precisely dated records are needed from many more sites before we can fully elucidate the complex late holocene glacial history of this region

reconstruction of holocene glacier history from distal sources glaciofluvial stream bank mires and a glaciolacustrine sediment core near sota saeter breheimen southern norway this study attempts to reconstruct the holocene glacier history of breheimen southern norway from four stream bank mire sites and a downstream lake sediment core near sota saeter based on lithostr

holocene fluctuations of bregne ice cap scoresby sund east greenland a proxy for climate along the greenland ice sheet margin abstract the greenland ice sheet is a major component of the arctic cryosphere and the magnitude of its response to future climate changes remains uncertain longer term records of climate near the ice sheet margin provide information about natural climate variability and can be used to understand the causes of past changes in the greenland ice sheet as a proxy for holocene climate near the ice sheet margin we reconstruct the fluctuations of bregne ice cap in the scoresby sund region of central east greenland bregne is a small ice cap 2 5 km 2 in area and responds sensitively to summer temperatures we employ a multi proxy approach to reconstruct the ice cap fluctuations using geomorphic mapping 10 be ages of boulders and bedrock and lake sediment records past extents of bregne ice cap are marked by moraines and registered by sediments in downvalley lakes 10 be ages of bedrock and boulders outboard of the moraines indicate that bregne ice cap was within 250 m of its present day limit by at least 10 7 ka multi proxy data from sediments in two move lake located downvalley from bregne ice cap indicate that the ice cap likely completely disappeared during early and middle holocene time increasing magnetic susceptibility and percent clastic material from 6 5 to 1 9 cal ka bp in two move lake sediments suggest progressively colder conditions and increased snow accumulation on the highlands west of the lake laminated silt deposited at 2 6 cal ka bp and 1 9 cal ka bp to present registers the onset and persistence of bregne ice cap during the late holocene 10 be ages of boulders on an unweathered unvegetated moraine in the bregne ice cap forefield range from 0 74 to 9 60 ka the youngest 10 be age 0 74 ka likely represents the age of the moraine whereas older ages may be due to 10 be inherited from prior periods of exposure this late holocene moraine marks the second largest advance of the ice cap since deglaciation of the region at the end of the last ice age the oldest moraine in the forefield dates to 2 6 cal ka bp the fluctuations of bregne ice cap were likely influenced by northern hemisphere summer insolation throughout the holocene and abrupt late holocene cold events

climate reconstruction since the little ice age by modelling koryto glacier kamchatka peninsula russia based on the field data at koryto glacier kamchatka peninsula russia we constructed a one dimensional numerical glacier model which fits the behaviour of the glacier the analysis of meteorological data from the nearby station suggests that the recent rapid retreat of the glacier since the mid 20th century is likely to be due to a decrease in winter precipitation using the geographical data of the glacier terminus variations from 1711 to 1930 we reconstructed the fluctuation in the equilibrium line altitude by means of the glacier model with summer temperatures inferred from tree ring data the model suggests that the winter precipitation from the mid 19th to the early 20th century was about 10 less than that at present this trend is close to consistent with ice core results from the nearby ice cap in the central kamchatka peninsula

late holocene glacier expansion in the cariboo and northern rocky mountains british columbia canada abstract castle creek glacier in the cariboo mountains of british columbia remained close to its little ice age limit for most of the past 1500 years without significant recession until the 20th century this conclusion is based on radiocarbon dated detrital and in situ plant material overrun by the glacier and the sedimentary record from informally named on off lake which received clastic sediments only when castle creek glacier crossed a hydrologic divide 330 m upvalley of the little ice age limit plant macrofossils recovered from the transition between basal inorganic silt and overlying organic silty clay in a sediment core from the lake indicate that the glacier first retreated behind the divide ca 10 92 9 70 ka ages of 8 97 8 61 and 5 58 5 53 ka on detrital wood from the glacier s forefield may record earlier advances but the first unequivocal evidence of glacier expansion is from an overridden stump with an age of 4 96 4 45 ka continuous accumulation of gyttja within on off lake however indicates that castle creek glacier did not cross the hydrologic divide at any time during the first half of the holocene glacigenic sediments began to accumulate in the lake between 2 73 and 2 49 ka indicating that castle creek glacier expanded beyond the hydrologic divide at that time a coincident advance is also recorded in the northern rocky mountains of british columbia at kwadacha glacier which overran a vegetated surface at 2 69 2 36 ka clastic sedimentation in on off lake ceased soon after the bridge river volcanic eruption 2 70 2 35 ka indicating that castle creek glacier retreat to a position upvalley of the divide at that time sedimentation resumed before 1 87 1 72 ka when the glacier advanced again past the hydrologic divide following a second retreat castle creek glacier advanced across the divide a final time at ca 1 54 1 42 ka the snout of the glacier remained less than 330 m upvalley of the little ice age moraine until the early twentieth century when annual moraines indicate rapid frontal recession to a position upvalley of the hydrologic divide these data collectively indicate that glaciers in the cariboo mountains of british columbia nearly achieved their all time holocene limits as early as 2 73 2 49 ka and climatic conditions in the early 20th century abruptly ended a 1500 year period favoring glacier expansion

lateglacial and early holocene palaeoclimatic reconstruction based on glacier fluctuations and equilibrium line altitudes at northern folgefonna hardanger western norway northern folgefonna c 23 km 2 is a nearly circular maritime ice cap located on the folgefonna peninsula in hardanger western norway by combining the position of marginal mor aines with ams radiocarbon dated glacier meltwater induced sediments in proglacial lakes draining northern folgefonna a continuous high resolution record of variations in glacier size and equili brium line altitudes elas during the lateglacial and early holocene has been obtained after the termination of the younger dryas c 11 500 cal yr bp a short lived 100 150 years climatically induced glacier readvance termed the jondal event 1 occurred within the preboreal oscillation pbo c 11 100 cal yr bp bracketed to 10 550 10 450 cal yr bp a second glacier readvance is named the jondal event 2 a third readvance occurred about 10 000 cal yr bp and corresponds with the erdalen event 1 recorded at jostedalsbreen an exponential relationship between mean solid winter precipitation and ablation season temperature at the ela of norwegian glaciers is used to reconstruct former variations in winter precipitation based on the corresponding ela and an indepen dent proxy for summer temperature compared to the present the younger dryas was much colder and drier the jondal event 1 pbo was colder and somewhat drier and the jondal event 2 was much wetter the erdalen event 1 started as rather dry and terminated as somewhat wetter varia tions in glacier magnitude elas and corresponding palaeoclimatic reconstructions at northern folge fonna suggest that low altitude cirque glaciers lowest altitude of marginal moraines 290 m in the area existed for the last time during the younger dryas these low altitude cirque glaciers of sug gested younger dryas age do not fit into the previous reconstructions of the younger dryas ice sheet in hardanger copyright 2005 john wiley sons ltd

catastrophic landslide deposits in the karakoram himalaya in july 1986 three catastrophic landslides deposited about 20 x 106 cubic meters of debris on bualtar glacier in the karakoram himalaya a sudden acceleration and superficial breakup of the glacier provided an opportunity to examine the fresh deposits in depth beneath a surface layer of large boulders finer materials mainly sand and silt made up half of the total volume the fine materials were formed during the rock avalanche from mostly intact massive rock of the source zone velocity estimates suggest that this disaggregation occurred in less than 2 minutes coarse materials remained in bands of uniform lithology but the fine materials had diffused throughout the landslides a small amount of carbonate appears to have been calcined by frictional heating presumably at the base of the initial sliding masses these observations are relevant to understanding the mechanisms of catastrophic landslides other nearby rock avalanche deposits indicate that landslides are an important geomorphic process in the area and that they pose a continuing risk to human activity

geometry and quaternary kinematics of fold and thrust units of southwestern taiwan structural and paleostress analyses provide new insights into the quaternary kinematics of the outermost fold and thrust units of southwestern taiwan foothills the frontal folds are interpreted as fault related folds and their tectonic evolution through space and time is tightly constrained fold development is correlated with reef building on top of the anticlines moreover we provide field evidence that nw se fault zones oblique to the structural grain of the belt probably acted as transfer fault zones during the the quaternary fold thrust emplacement two successive quaternary stress regimes are evidenced in southwestern taiwan a nw se compression followed by a recent nearly e w compression the latter shows an along strike change from pure e w contraction to the north to perpendicular n s extension in the south this southward decrease in n s confinement probably represents the on land signature of the incipient quaternary tectonic escape predicted by analogue and numerical modelling and evidenced at present day by global positioning system data

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

holocene climate inferred from glacier extent lake sediment and tree rings at goat lake kenai mountains alaska usa lake sediment glacier extent and tree rings were used to reconstruct holocene climate changes from goat lake at 550 m asl in the kenai mountains south central alaska radiocarbon dated sediment cores taken at 55 m water depth show glacial lacustrine conditions until about 9500 cal yr bp followed by organic rich sedimentation with an overall increasing trend in organic matter and biogenic silica content leading up to the little ice age lia through most of the holocene the northern outlet of the harding icefield remained below the drainage divide that currently separates it from goat lake a sharp transition from gyttja to inorganic mud about ad 1660 signifies the reappearance of glacier meltwater into goat lake during the lia marking the maximum holocene postglacial extent meltwater continued to discharge into the lake until about ad 1900 a 207 yr tree ring series from 25 mountain hemlocks growing in the goat lake watershed correlates with other regional tree ring series that indicate an average summer temperature reduction of about 1 c during the 19th century compared with the early mid 20th century cirque glaciers around goat lake reached their maximum lia extent in the late 19th century assuming that glacier equilibrium line altitudes ela are controlled solely by summer temperature then the cooling of 1 c combined with the local environmental lapse rate would indicate an ela lowering of 170 m in contrast reconstructed elas of 12 cirque glaciers near goat lake average only 34 18 m lower during the lia the restricted ela lowering can be explained by a reduction in accumulation season precipitation caused by a weakening of the aleutian low pressure system during the late lia copyright 2008 john wiley sons ltd

changes in glacier extent on north novaya zemlya in the twentieth century glacier retreat on north novaya zemlya for the past century was documented by registering glacier terminus positions from expedition and topographic maps and remotely sensed images recession of tidewater calving glaciers on north novaya zemlya in the first half of the twentieth century was relatively rapid 300 m yr 1 consistent with post little ice age warming documented by a 122 year instrumental record from malye karmakuly the glaciers completed 75 to 100 of the net twentieth century retreat by 1952 between 1964 and 1993 half of the studied glaciers were stable the remainder retreated modest distances of 0 75 elevated sst in the barents sea appear to reflect increased advecti