periglacial trimlines and nunataks of the last glacial maximum the gap of dunloe southwest ireland during the last main phase of glaciation 26 13 ka an ice cap developed in southwest ireland and ice from a dispersal centre in the vicinity of kenmare flowed north through the gap of dunloe in the macgillycuddy s reeks on surrounding hillsides a weathering limit separates ice moulded bedrock on low ground from frost weathered terrain above assessment of bedrock dilation joint characteristics schmidt hammer r value data and clay sized mineral contents of basal soil samples demonstrate significant contrasts in the degree of weathering above and below this limit the weathering limit declines in altitude along former ice flow lines and is confluent with morainic deposits on the eastern side of the gap this supports the assertion that the high level weathering limit is a periglacial trimline that marks the former maximum upper limit of the body of ice which occupied the gap of dunloe during the last glacial maximum lgm reconstruction of the former ice surface profile from periglacial trimline limits on the eastern side of the gap yields a mean estimate for basal shear stress of 106 5 kpa this value suggests that the ice mass which occupied the gap of dunloe at the lgm was warm based and flowed on a bedrock substrate copyright 2004 john wiley sons ltd

quantitative roundness analysis of coastal boulder deposits abstract the sedimentology of coastal boulder deposits cbd is little known these deposits and especially the largest clasts within them which commonly weigh many 10s of tonnes are of increasing interest because they attest to extreme energy wave events acting well above the high tide mark in some cases 40 m above high water and 100 m inland recent observations have made clear that storm waves rather than tsunami are important in both creating and activating these deposits but beyond that we know little about their hydrodynamics or the relative frequency of boulder movement and how this might vary with topographic setting roundness is a first order characteristic that preserves a record of deposit reworking it can tell us whether clasts move around much after they have been created from bedrock or whether they are emplaced into cbd with little or no subsequent transport but because roundness has historically been difficult to measure most roundness estimates in the literature are based on qualitative visual assessment and are therefore of limited analytical value fully reproducible roundness measurements are possible however and in the case of boulders they can be acquired quite easily using the kirkbride 2005 device in combination with a trigonometric formula presented here cbd at locations in ireland and scotland provide a test case demonstrating the utility of quantitative boulder roundness measurements the 567 clasts we measured are generally angular but a substantial proportion shows some degree of rounding most importantly there are demonstrable consistent patterns relating topography and roundness there is a strong and unsurprising inverse correlation between clast roundness and deposit elevation there is no first order relationship between roundness and inland distance but there is a power law inverse relationship between rounding and steepness ratio of elevation to distance inland the greatest degree of rounding is found in cbd located at the back of gentle coastal platforms with gradual slopes these relationships provide new insights into cbd sedimentology which we hope will be probed and tested in future studies

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

stable isotope records of late quaternary climate and hydrology from mediterranean lakes the isomed synthesis lake isotope records can be used to assess the spatial coherency of late quaternary climate change across the circum mediterranean region we place modern and palaeo data within a simple conceptual lake response model to show that the isotope hydrology of most mediterranean lakes has been influenced strongly by water balance even in those systems that are chemically dilute i e freshwater 18o data on biogenic and endogenic carbonates from 24 lake basins are used to reconstruct multi millennial scale trends since the lgm while it is difficult to make direct comparisons between lake records in terms of single climatic parameters coherent regional isotopic trends can be identified during glacial times mediterranean lakes deposited carbonates isotopically heavier in 18o compared to the holocene partly due to source area effects isotopic enrichment was most marked during intervals corresponding to the h1 and younger dryas events confirming that late pleistocene cold stages in the north atlantic region were marked by aridity around much of the mediterranean almost all mediterranean lake records shifted to more depleted isotopic values during the last glacial interglacial transition lgit this shift is the reverse of the trend which characterised the same transition in lakes from northern and central europe and suggests that temperature changes were not an important direct driver of mediterranean lake isotopic records over glacial interglacial timescales in the early holocene many lakes in the eastern part of the region were more depleted isotopically than in recent millennia this corresponds with marine sapropel formation both chronologically and geographically and implies that increases in local rainfall contributed significantly to the creation of a freshwater lid and anoxia in the east mediterranean sea in contrast no such pattern is currently apparent from lake isotope records from the west mediterranean suggesting a possible nw se contrast in climate history during the holocene

geomorphology and weathering characteristics of erratic boulder trains on tierra del fuego southernmost south america implications for dating of glacial deposits abstract erratic boulder trains ebts are a useful glacial geomorphological feature because they reveal former ice flow trajectories and can be targeted for cosmogenic nuclide exposure dating however understanding how they are transported and deposited is important because this has implications for palaeoglaciological reconstructions and the pre exposure and or erosion of the boulders in this study we review previous work on ebts which indicates that they may form subglacially or supraglacially but that large angular boulders transported long distances generally reflect supraglacial transport we then report detailed observations of ebts from tierra del fuego southernmost south america where their characteristics provide a useful framework for the interpretation of previously published cosmogenic nuclide exposure dates we present the first comprehensive map of the ebts and analyse their spatial distribution size and physical appearance results suggest that they were produced by one or more supraglacial rock avalanches in the cordillera darwin and were then transported supraglacially for 100 s of kilometres before being deposited rock surface weathering analysis shows no significant difference in the weathering characteristics of a sequence of ebts previously hypothesized to be of significantly different age i e different glacial cycles we interpret this to indicate that the ebts are much closer in age than previous work has implied this emphasises the importance of understanding ebt formation when using them for cosmogenic nuclide exposure dating

relationship between uplift of the metamorphic core of the southernmost andes and shortening in the magallanes foreland fold and thrust belt tierra del fuego chile rocks containing upper amphibolite facies assemblages reflecting mesozoic cenozoic metamorphism form the 5000 km2 core of the southernmost andes in cordillera darwin approximately 55 s latitude results from mapping along a 50 km continuous transect across the southernmost andes on the main island of tierra del fuego show structural relationships between the late cretaceous to early tertiary uplift of the metamorphic core in northern cordillera darwin and mid cretaceous to paleogene shortening in the adjacent magallanes foreland fold and thrust belt new data indicate that pre late jurassic basement schists exposed along the northeastern edge of cordillera darwin were uplifted along a discrete brittle continent vergent thrust fault this thrust overlies a series of thin skinned thrusts and back thrusts that affect mesozoic tertiary rocks of the magallanes foreland basin the thrust that uplifts basement schists is interpreted to have formed out of sequence with respect to the thin skinned structures because it placed the schists over previously shortened lower cretaceous sedimentary strata of the magallanes basin the geometry of thrusts observed across the transect and their inferred sequence of deformation indicate a thick skinned contractional mechanism for uplift of the pre late jurassic schists of northern cordillera darwin relative to the structural level of metamorphic basement in the magallanes foreland the relative time of out of sequence thrusting and basement uplift inferred from thrust geometries in this paper is consistent with the latest cretaceous to early tertiary episode of rapid exhumation and cooling of the metamorphic core of the southern andean orogen determined in previous structural metamorphic and geochronological studies

surface lowering of limestone pavement as determined by cosmogenic 36cl analysis determination of the rate and total amount of limestone pavement surface lowering is a critical issue in developing models of regional landscape change in limestone terrain erratic capped pedestals have frequently been used for this purpose but problems concerning definition and measurement of pedestal height and the absence of a secure timeframe for erratic emplacement have resulted in conflicting interpretations we have used cosmogenic 36cl to establish the emplacement age of erratic boulders and the total amount of pavement surface lowering at sites in northwest england since erratic emplacement at 17 9 ka the limestone pavement has been lowered by 22 45 cm average 33 10 cm assuming lowering was continuous although indicating some spatial heterogeneity the results contrast with earlier reported values based on the measurement of pedestal heights and inferred age for deglaciation we consider that changes in climate and the character and duration of regolith covers to have been important influences in promoting surface lowering it is argued that nivation chemical and mechanical snow related processes associated with several cool cold periods is likely to have played an important role in surface lowering complicating factors associated with surface lowering thickness and longevity of snow and regolith covers are identified but as yet cannot be quantified copyright 2012 john wiley sons ltd

glacial hydrologic conditions in the black sea reconstructed using geochemical pore water profiles abstract chloride and 18 o compositions of interstitial water extracted from a long sediment core retrieved from the nw coast of the black sea allowed us to constrain the main hydrologic changes of the back sea during the late pleistocene and holocene prior to its reconnection with the mediterranean sea through the marmara sea at approximately 9000 calendar yr before present 9 ka cal bp the black sea has evolved as a fresh to brackish water lake at the time of reconnection hydrologic changes were drastic bottom water salinities changed from a few psu practical salinity unit to 22 psu since solutes in the interstitial water column within sediments are advected and diffused the measured concentrations do not reflect those of past bottom waters in order to reconstruct these former concentrations we used an advection diffusion model different scenarios of bottom water chloride and 18 o variations were accounted for in this model in order to simulate present day vertical profiles for concentrations of interstitial water in order to compare them to measured ones the comparison suggests that the glacial black sea was a homogeneous freshwater lake with a 18 o of 10 and a salinity of 1 psu modern hydrologic conditions would only have been reached at 2 ka cal bp concomitant with the onset of coccolith rich thin layers that characterize modern basin sediments such delayed salinization over 7000 yr in the basin may have been due to higher precipitation during the early holocene we also simulated the impact of a catastrophic reconnection and a smoother reconnection both salinity scenarios lead to undistinguishable modelled present day profiles indicating that the precise impact of the last reconnection was lost due to the advection diffusion processes

abrupt changes of temperature and water chemistry in the late pleistocene and early holocene black sea new mg ca sr ca and published stable oxygen isotope and 87sr 86sr data obtained on ostracods from gravity cores located on the northwestern black sea slope were used to infer changes in the black sea hydrology and water chemistry for the period between 30 to 8 ka b p calibrated radiocarbon years the period prior to 16 5 ka b p was characterized by stable conditions in all records until a distinct drop in 18o values combined with a sharp increase in 87sr 86sr occurred between 16 5 and 14 8 ka b p this event is attributed to an increased runoff from the northern drainage area of the black sea between heinrich event 1 and the onset of the bolling warm period while the mg ca and sr ca records remained rather unaffected by this inflow they show an abrupt rise with the onset of the bolling allerod warm period this rise was caused by calcite precipitation in the surface water which led to a sudden increase of the sr ca and mg ca ratios of the black sea water the stable oxygen isotopes also start to increase around 15 ka b p although in a more gradual manner due to isotopically enriched meteoric precipitation while sr ca remains constant during the following interval of the younger dryas cold period a decrease in the mg ca ratio implies that the intermediate water masses of the black sea temporarily cooled by 1 2 c during the younger dryas the 87sr 86sr values drop after the cessation of the water inflow at 15 ka b p to a lower level until the younger dryas where they reach values similar to those observed during the last glacial maximum this might point to a potential outflow to the mediterranean sea via the sea of marmara during this period the inflow of mediterranean water started around 9 3 ka b p which is clearly detectable in the abruptly increasing mg ca sr ca and 87sr 86sr values the accompanying increase in the 18o record is less pronounced and would fit to an inflow lasting 100 a

the evolution of the patagonian ice sheet from 35 ka to the present day patice abstract we present patice a gis database of patagonian glacial geomorphology and recalibrated chronological data patice includes 58 823 landforms and 1 669 geochronological ages and extends from 38 s to 55 s in southern south america we use these data to generate new empirical reconstructions of the patagonian ice sheet pis and subsequent ice masses and ice dammed palaeolakes at 35 ka 30 ka 25 ka 20 ka 15 ka 13 ka synchronous with the antarctic cold reversal 10 ka 5 ka 0 2 ka and 2011 ad at 35 ka the pis covered of 492 6 x103 km2 had a sea level equivalent of 1 496 mm was 350 km wide and 2090 km long and was grounded on the pacific continental shelf edge outlet glacier lobes remained topographically confined and the largest generated the suites of subglacial streamlined bedforms characteristic of ice streams the pis reached its maximum extent by 33 28 ka from 38 s to 48 s and earlier around 47 ka from 48 s southwards net retreat from maximum positions began by 25 ka with ice marginal stabilisation then at 21 18 ka which was then followed by rapid irreversible deglaciation by 15 ka the pis had separated into disparate ice masses draining into large ice dammed lakes along the eastern margin which strongly influenced rates of recession glacial readvances or stabilisations occurred at least at 14 13 ka 11 ka 6 5 ka 2 1 ka and 0 5 0 2 ka we suggest that 20th century glacial recession a 1 is occurring faster than at any time documented during the holocene

surface and sub surface schmidt hammer rebound value variation for a granite outcrop this study presents rock strength variations at granite outcrops and in subsurface vertical profiles in the jizerske hory mountains czech republic schmidt hammer rebound values in subsurface profiles change gradually from the bedrock surface downward an exponential relation has been observed between the r values and depth in rock outcrops to a depth of around 4 5 m the exponential nature of the curve indicates that rock hardness increases more rapidly with depth in the uppermost 1 m section of the rock profile a detailed study of rebound values obtained from both intact and polished rock exposures reveal effects of surface grinding on results of the schmidt hammer method the range of data collected increases after grinding allowing more precise discrimination of rock surfaces in respect of age and weathering the schmidt hammer method may be used effectively as a relative age dating tool for rock surfaces that originated during the late pleistocene it is concluded that this time limitation can be significantly mitigated by surface grinding before measurement copyright 2010 john wiley sons ltd

pattern style and timing of british irish ice sheet retreat shetland and northern north sea sector the offshore sector around shetland remains one of the least well studied parts of the former british irish ice sheet with several long standing scientific issues unresolved these key issues include i the dominance of a locally sourced shetland ice cap vs an invasive fennoscandian ice sheet ii the flow configuration and style of glaciation at the last glacial maximum i e terrestrial vs marine glaciation iii the nature of confluence between the british irish and fennoscandian ice sheets iv the cause style and rate of ice sheet separation and v the wider implications of ice sheet uncoupling on the tempo of subsequent deglaciation as part of the britice chrono project we present new geological seabed cores geomorphological marine geophysical and geochronological data from the northernmost sector of the last british irish ice sheet north of 59 5 n to address these questions the study area covers ca 95 000 km2 an area approximately the size of ireland and includes the islands of shetland and the surrounding continental shelf some of the continental slope and the western margin of the norwegian channel we collect and analyse data from onshore in shetland and along key transects offshore to establish the most coherent picture so far of former ice sheet deglaciation in this important sector alongside new seabed mapping and quaternary sediment analysis we use a multi proxy suite of new isotopic age assessments including 32 cosmogenic nuclide exposure ages from glacially transported boulders and 35 radiocarbon dates from deglacial marine sediments to develop a synoptic sector wide reconstruction combining strong onshore and offshore geological evidence with bayesian chronosequence modelling the results show widespread and significant spatial fluctuations in size shape and flow configuration of an ice sheet ice cap centred on or to the east of the orkney shetland platform between 30 and 15 ka bp at its maximum extent ca 26 25 ka bp this ice sheet was coalescent with the fennoscandian ice sheet to the east between 25 and 23 ka bp the ice sheet in this sector underwent a significant size reduction from ca 85 000 to 50 000 km2 accompanied by several ice margin oscillations soon after connection was lost with the fennoscandian ice sheet and a marine corridor opened to the east of shetland this triggered initial and unstable re growth of a glaciologically independent shetland ice cap ca 21 20 ka bp with a strong east west asymmetry with respect to topography ice mass growth was followed by rapid collapse from an area of ca 45 000 km2 to ca 15 000 km2 between 19 and 18 ka bp stabilizing at ca 2000 km2 by 17 ka bp final deglaciation of shetland occurred ca 17 15 ka bp and may have involved one or more subsidiary ice centres on now submerged parts of the continental shelf we suggest that the unusually dynamic behaviour of the northernmost sector of the british irish ice sheet between 21 and 18 ka bp characterized by numerous extensive ice sheet ice mass readvances rapid loss and flow redistributions was driven by significant changes in ice mass geometry ice divide location and calving flux as the glaciologically independent ice cap adjusted to new boundary conditions we propose that this dynamism was forced to a large degree by internal glaciological factors specific to the strongly marine influenced shetland ice cap

a mid european decadal isotope climate record from 15 500 to 5000 years b p oxygen isotope ratios of precipitation delta18op inferred from deep lake ostracods from the ammersee southern germany provide a climate record with decadal resolution the record in detail shows many of the rapid climate shifts seen in central greenland ice cores between 15 000 and 5000 years before the present b p negative excursions in the estimated delta18op from both of these records likely reflect short weakenings of the thermohaline circulation caused by episodic discharges of continental freshwater into the north atlantic deviating millennial scale trends however indicate that climate gradients between europe and greenland changed systematically reflecting a gradual rearrangement of north atlantic circulation during deglaciation

periglacial trimlines former nunataks and the altitude of the last ice sheet in wester ross northwest scotland high level weathering limits separating ice scoured topography from frost weathered detritus were identified on 28 mountains in wester ross at altitudes of 700 960 m and a further 22 peaks support evidence of ice scouring to summit level weathering limits are defined most clearly on sandstone and gneiss which have resisted frost shattering during the late devensian lateglacial but can also be distinguished on schists and quartzite schmidt hammer measurements and analyses of clay mineral assemblages indicate significantly more advanced rock and soil weathering above the weathering limits the persistence of gibbsite above weathering limits indicates that they represent the upper limit of late devensian glacial erosion the regular decline of weathering limit altitudes along former flowlines eliminates the possibility that the weathering limits represent former thermal boundaries between protective cold based and erosive warm based ice the weathering limits are therefore interpreted as periglacial trimlines that define the maximum surface altitude of the last ice sheet calculated basal shear stresses of 50 95 kpa are consistent with this interpretation reconstruction of ice sheet configuration indicates that the former ice shed lay above 900 m along the present watershed and that the ice surface descended northwestwards with broad depressions along major troughs and localised domes around independent centres of ice dispersal extrapolation of the ice surface gradient and altitude suggests that the ice sheet did not overrun the outer hebrides but was confluent with the independent outer hebrides ice cap in the north minch basin erratics located up to 140 m above the reconstructed ice surface are inferred to have been emplaced by a pre late devensian ice sheet or ice sheets of unknown age 1997 john wiley sons ltd

dynamics of former ice lobes of the southernmost patagonian ice sheet based on a glacial landsystems approach reconstructions of former ice masses from glacial geomorphology help to constrain the nature and timing of glaciation in relation to climatic forcing this paper presents a new reconstruction of the glacial history of five ice lobes in southernmost south america the bahia inutil san sebastian magellan otway skyring and rio gallegos ice lobes we use previous geomorphological mapping of glacial landforms to reconstruct former glacial limits and proglacial lakes demarcate flow sets from the distribution of glacial lineations and evaluate glacial landsystem signatures and their palaeoglaciological implications evidence suggests that the ice lobes predominantly reflect active temperate glacial landsystems which may have switched to polythermal systems when periods of cold based ice developed ephemerally this complex landsystem signature implies that the ice lobes were sensitive to regional climate variability with active re advances during overall retreat of the ice margins there is also evidence for periods of fast ice flow and possible surge like activity in the region followed by the rapid retreat or even collapse of some of the ice lobes in association with proglacial lakes constraining our new reconstruction with published chronological information suggests that at least some of the ice lobes advanced before the global last glacial maximum glgm ca 26 5 19 ka during the last glacial cycle our new reconstruction demonstrates a more complex picture of ice dynamics than has previously been portrayed and one in which the advance and retreat of the ice lobes was likely to have been primarily driven by changes in climate as such ice advances before the glgm in the southernmost part of the patagonian ice sheet are likely to indicate a wider climatic forcing at this time

depositional settings and history of the lower miocene fleming group refugio county texas as defined using seismic geomorphology abstract a study of the lower miocene fleming group in refugio county texas from 3 d seismic and wireline log data documents continuous strandplain and associated lower coastal plain fluvial systems along a wave dominated shoreline this study delineates and characterizes through the interpretation of seismic attributes and seismic geomorphology maps from 15 horizons three principal styles of stratal patterns 1 parallel and subparallel strike continuous sets of beach ridge and swale deposits within a strandplain system that prograded at least 12 km 2 sinuous channel belts in a coeval mixed load meanderbelt system and 3 acoustically dim nearly featureless seismic attribute patterns that record homogenous and topographically subdued shallow marine mudstones associated with transgressive marine deposits and flooding surfaces holocene depositional analogs for these lower miocene sandy strandplain deposits include the nayarit coastline in mexico whereas the lower coastal plain between galveston and corpus christi texas serves as an appropriate analog for mixed load meanderbelt systems the lower miocene coastline in refugio county consists of a regressive phase that was punctuated by two transgressive phases these episodes of marine transgression correspond to the anahuac formation and the marginulina a shale respectively succeeding events record complex amalgamated beach ridge deposits and coeval fluvial channel systems that exhibit patterns of channel migration erosion incision and downdip fusion of channel belts this study concludes that potential reservoir geometries and architectures in the lower miocene succession are much more complex than previously inferred the result of rapidly fluctuating and evolving strike fed shoreline systems and contemporaneous fluvial dip dispersal systems some manifested by shore parallel trends confined in swales improved reservoir development strategies in this prolific hydrocarbon bearing play should be guided by distribution of sandy depositional elements and the paleogeographic setting

cosmogenic nuclide measurements in southernmost south america and implications for landscape change we measured in situ 10be 26al and 36cl on glacial deposits as old as 1 1 myr in the southernmost part of patagonia and on northern tierra del fuego to understand boulder and moraine and by inference landscape changes nuclide concentrations indicate that surface boulders have been exposed for far less time than the ages of moraines they sit upon the moraine ages are themselves constrained by previously obtained 40ar 39ar ages on interbedded lava flows or u series and amino acid measurements on related non glacial marine deposits we suggest that a combination of boulder erosion and their exhumation from the moraine matrix could cause the erratics to have a large age variance and often short exposure histories despite the fact that some moraine landforms are demonstrably 1 myr old we hypothesize that fast or episodic rates of landscape change occurred during glacial times or near the sea during interglacials comparison with boulder erosion rates and exhumation histories derived for the middle latitudes of semi arid patagonia imply different geomorphic processes operating in southernmost south america we infer a faster rate of landscape degradation towards the higher latitudes where conditions have been colder and wetter

high frequency 4th order sequence stratigraphy of early miocene deltaic shorelines offshore texas and louisiana abstract well logs and 3d seismic reflection data are integrated to image lower miocene depocenters of the upper texas and westernmost louisiana coastal and offshore areas although previously interpreted at a large scale 3rd order cycles the detailed stratigraphy and depositional history of the early miocene succession has not been fully developed the upper lower miocene interval from robulus l mfs10 to amphistegina b mfs9 has been further subdivided into five 4th order cycles each 200 300 m thick to provide finer scale stratigraphic detail and interpretation of depositional environments results of the finer scale correlations are presented in a series of sandstone percent maps overall the maps display a strike elongate sub parallel to the present day coastline orientation for the sandstone bodies which thin to the southeast basinward net sandstone thickness is relatively low in older cycles and increases in younger cycles suggesting an overall progradation of the deltaic system into the mapped area through time continued marine regression and southward movement of the shoreline are also confirmed by seismic amplitude maps after a major transgression associated with robulus l deltaic progradation occurred under rising sea level conditions deltaic sediments prograded southward and sandstone brought to the upper texas coast was distributed laterally by longshore currents to form strandplain coast lines maximum regression occurred during the interval mfs9 2 to mfs9 3 when a deltaic depocenter formed offshore texas in east high island area however sandstone thickness progressively decreased laterally to the east offshore louisiana where more shale was present and marine processes reworked deltaic derived sandstones into shore parallel bars there was a clear retreat of the shoreline during the youngest cycle marking the beginning of transgression associated with amphistegina b detailed stratigraphic interpretation at a 4th order scale shows more variability in the dominant shoreline processes during early miocene than previously thought recognition of sedimentary systems variability at a 4th order scale is critical for improved hydrocarbon exploration and in understanding potential future co2 storage in the area

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

an abrupt drowning of the black sea shelf abstract during latest quaternary glaciation the black sea became a giant freshwater lake the surface of this lake drew down to levels more than 100 m below its outlet when the mediterranean rose to the bosporus sill at 7 150 yr bp 1 saltwater poured through this spillway to refill the lake and submerge catastrophically more than 100 000 km2 of its exposed continental shelf the permanent drowning of a vast terrestrial landscape may possibly have accelerated the dispersal of early neolithic foragers and farmers into the interior of europe at that time

rock avalanches that travel onto glaciers and related developments karakoram himalaya inner asia abstract catastrophic rock slope failures in rugged terrain commonly generate rock avalanches when these occur in glacier basins the extent of landslide run out and its emplacement geometry are affected by movement over ice substantial modifications of glacier activity and sedimentation can follow ice activity leads to rapid modification transport and dispersal of landslide debris the nature of these interactions is described from observations over 20 years at bualtar glacier in the karakoram in august 1986 rock avalanches descended onto the ablation zone of the glacier their moisture content and patterns of deposition were affected by travel over ice glacier movement increased sharply at and below the rock avalanche deposits and within a few months the glacier surged a second surge occurred 2 years later major slope failures and debris flows were triggered beyond the ice margins and ponded melt water led to small outburst floods by 2005 the landslide material had been transported some 9 km about one third of this distance in the surges eventually it was fully reworked to become less readily distinguishable from other heavy supraglacial debris a large area of thickened ice persisted where the debris reduced ablation a positive impact on mass balance equivalent to a 20 increase in annual accumulation however it occurred as a moving segment of the ablation zone in 10 years it had in effect replaced the mass transferred in the surges data for the mid 1980s indicate the rock avalanches exceeded pre existing supraglacial debris by roughly five times and over a 30 year period will equal almost 500 years of normal supraglacial transport to the glacier margins other impacts of the episode suggest a doubling of this contribution to denudation similar developments were observed at three other glaciers where recent rock avalanches occurred and at twenty one prehistoric rock avalanches newly identified as having spread over glaciers it seems inadequate to treat such events only as singular extremes or the landslide and glacial processes separately here they are interpreted as contributing to disturbance regime landscapes whose history reflects episodic and regionally specific responses to strong interference among different earth surface processes they generate polygenetic deposits and landforms that are morphologically complex individual episodes involve decades to millennia their numbers and repetition can over ride or redirect geotectonic and climatic conditions it is suggested they are major but hitherto misread or neglected elements of landform evolution in the karakoram and perhaps in other high mountains

southern patagonian glacial chronology for the last glacial period and implications for southern ocean climate the magellan region of southern south america is in a unique setting at 50 s on the equatorial side of the antarctic frontal zone to record in detail terrestrial glacial to interglacial events a 10be chronology shows growth and millennial fluctuations of a patagonian ice sheet between 25 and 17 6 17 0 cal ka in the strait of magellan the maximum ice margin position is dated to 24 6 0 9 ka and other moraine ages are 18 5 1 8 and 17 6 0 2 ka mean 1 standard deviation in bahia inutil dated moraine ages are 20 4 1 2 and 17 3 0 8 ka the chronology of the local last glacial maximum lgm reveals a record of atmospheric cooling that was broadly in phase with changes in southern ocean conditions such as sea ice fluctuations and surface water characteristics published modeling results indicate that a decline in temperature of 6 c and slight drying over southernmost patagonia could simulate the growth and sustained presence of an ice sheet to the mapped lgm limit the terrestrial record in southern patagonia and marine records in adjacent oceans indicate mean northward movement of the antarctic frontal zone which caused the last southern south american ice age the antarctic frontal zone at present lies only 3 5 to the south some significant changes in the magellan region occurred in step with north atlantic region and the northern hemisphere for example the overall time span of the last glaciation and the timing of maximum ice extent were similar between the hemispheres despite maximum local summer insolation intensity in southern south america other characteristics of the southern patagonian glacial history differ from the north atlantic region specifically an out of phase relationship during deglaciation which is more similar to that of southern ocean and antarctic records

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

evaluating the timing of former glacier expansions in the tian shan a key step towards robust spatial correlations the timing of past glaciation across the tian shan provides a proxy for past climate change in this critical area correlating glacial stages across the region is difficult but cosmogenic exposure

what controls dead ice melting under different climate conditions a discussion abstract in the geological record hummocky dead ice moraines represent the final product of the melt out of dead ice processes and rates of dead ice melting in ice cored moraines and at debris covered glaciers are commonly believed to be governed by climate and debris cover properties here backwasting rates from 14 dead ice areas are assessed in relation to mean annual air temperature mean summer air temperature mean annual precipitation mean summer precipitation and annual sum of positive degree days the highest correlation was found between backwasting rate and mean annual air temperature however the correlation between melt rates and climate parameters is low stressing that processes and topography play a major role in governing the rates of backwasting the rates of backwasting from modern glacial environments should serve as input to de icing models for ancient dead ice areas in order to assess the mode and duration of deposition a challenge for future explorations of dead ice environments is to obtain long term records of field based monitoring of melt progression furthermore many modern satellite borne sensors have high potentials for recordings of multi temporal digital elevation models dems for detection and quantification of changes in dead ice environments in recent years high accuracy dems from airborne laser scanning altimetry lidar are emerging as an additional data source however time series of high resolution aerial photographs remain essential for both visual inspection and high resolution stereographic dem production

cosmogenic 10 be and 26 al exposure ages of glaciations in the frankland range southwest tasmania reveal a limited mis 2 ice advance abstract new mapping of the glacial geomorphology coupled with 10be and 26al exposure age dating of moraines on the flanks of the frankland range in south west tasmania indicate that glacier extent during mis 2 was far smaller than during earlier glaciations with the ice cover being confined to only the uppermost cirques of the range moraines further down the range flanks 50 150 m lower in altitude than the mis 2 dated advance indicate that glaciers were only slightly larger during earlier glaciations and depending on the interpretation of their exposure ages may range from mis 7 to mis 12 these older moraines are nested inside the maximum ice limits of an even more ancient and extensive glaciation defined by degraded valley floor moraines and coalescing glacio fluvial fans that remain undated but appear no younger than mis 12 patterns of glacial erosion and moraine deposition on the frankland range suggest that the more recent glaciations were increasingly influenced by the erosional morphology initiated by earlier glaciers microclimatic differences resulting from this earlier glacial topography were particularly influential determinants of glaciation during mis 2 these results are consistent with emerging evidence from studies of other ranges in southwest tasmania

cold glaciers erode and deposit evidence from allan hills antarctica here we report previously undescribed features of erosion and deposition by a cold polar glacier a recent study challenged the assumption that cold glaciers neither slide nor abrade their beds but no geological evidence was offered the features we describe include abrasion marks subglacial deposits glaciotectonically deformed substrate isolated blocks ice cored debris mounds and boulder trains all products of a recent cold ice advance and retreat mapping these features elsewhere in antarctica will document recent shifts in the east antarctic ice sheet margin providing new insight on regional mass balance changes

landscape evolution and ice sheet behaviour in a semi arid polar environment james ross island ne antarctic peninsula this study of landscape evolution presents both new modern and palaeo process landform data and analyses the behaviour of the antarctic peninsula ice sheet through the last glacial maximum lgm the holocene and to the present day six sediment landform assemblages are described and interpreted for ulu peninsula james ross island ne antarctic peninsula 1 the glacier ice and snow assemblage 2 the glacigenic assemblage which relates to lgm sediments and comprises both erratic poor and erratic rich drift deposited by cold based and wet based ice and ice streams respectively 3 the boulder train assemblage deposited during a mid holocene glacier readvance 4 the ice cored moraine assemblage found in front of small cirque glaciers 5 the paraglacial assemblage including scree pebble boulder lags and littoral and fluvial processes and 6 the periglacial assemblage including rock glaciers protalus ramparts blockfields solifluction lobes and extensive patterned ground the interplay between glacial paraglacial and periglacial processes in this semi arid polar environment is important in understanding polygenetic landforms crucially cold based ice was capable of sediment and landform genesis and modification this landsystem model can aid the interpretation of past environments but also provides new data to aid the reconstruction of the last ice sheet to overrun james ross island

palaeoenvironmental change in southern patagonia during the lateglacial and holocene implications for forest refugia and climate reconstructions abstract a high resolution palynological record from punta yartou fuego patagonia 53 51 s 70 08 w supported by lithostratigraphy radiocarbon dating and tephrochronology was examined to reconstruct the vegetation changes during the last glacial interglacial transition and the holocene following deglaciation from the last glacial maximum sometime before c 23 070 cal yr bp the vegetation was initially dominated by ericaceous shrubs and following modest climate amelioration between c 20 480 and 14 820 cal yr bp the environment favoured the spread of acaena the trend to a warmer and more humid climate was interrupted between c 14 820 and 13 560 cal yr bp when the vegetation community was dominated by cold tolerant herbs such as poaceae and asteraceae subfamily asteroideae suggesting an open treeless landscape with colder climatic conditions coeval with the antarctic cold reversal after c 13 560 cal yr bp a gradual rise in temperature and humidity is inferred from the colonisation of nothofagus a further warming and increase is inferred from the establishment of the forest steppe ecotone by c 12 900 cal yr bp the early holocene was then characterised by increasing development of nothofagus open canopy forest however between c 8080 and 5060 cal yr bp there was a significant reduction in the forest cover and high values of charcoal which suggest an intense arid phase leading to increased availability of dry fuel between c 5060 and 2170 cal yr bp there were centennial scale periods of increased wetter and colder climatic conditions the punta yartou record demonstrates the sensitivity of fuego patagonian forest to changes in the proximity and intensity of the southern westerly winds

evidence for a 55 50 ka early wisconsin glaciation of the cordilleran ice sheet yukon territory canada abstract cosmogenic 10be ages on boulders of 54 51 ka n 4 on a penultimate cordilleran ice sheet cis drift confirm that marine oxygen isotope stage mis 4 early wisconsin glaciation was extensive in parts of yukon territory the first confirmed evidence in the canadian cordillera we name the glaciation inferred from the mapped and dated drift the gladstone these results are in apparent contrast to the mis 6 illinoian age of the penultimate reid glaciation to the east in central yukon but are equivalent to exposure ages on mis 4 drift in alaska contrasting penultimate ice extents in yukon requires that different source areas of the northern cis in yukon responded differently to climatic forcing during glaciations the variation in glacier extent for different source areas likely relates to variation in precipitation during glaciation as the northern cis was a precipitation limited system causes for a variation in precipitation remain unclear but likely involve the style of precipitation delivery over the st elias mountains possibly related to variations in the aleutian low

timing and climatic impact of greenland interstadials recorded in stalagmites from northern turkey a 50 kyr long exceptionally well dated and highly resolved stalagmite oxygen 18o and carbon 13c isotope record from sofular cave in northwestern turkey helps to further improve the dating of greenland interstadials gi 1 and 3 12 timing of most gi in the sofular record is consistent within 10 to 300 years with the iconic hulu cave record larger divergences 500 years between sofular and hulu are only observed for gi 4 and 7 the sofular record differs from the most recent ngrip chronology by up to several centuries whereas age offsets do not increase systematically with depth the sofular record also reveals a rapid and sensitive climate and ecosystem response in the eastern mediterranean to gi whereas a phase lag of 100 years between climate and full ecosystem response is evident finally results of spectral analyses of the sofular isotope records do not support a 1 470 year pacing of gi

evidence for a rock avalanche origin for the hillocks moraine otago new zealand abstract a landform in otago new zealand previously interpreted as a glacial deposit has been investigated described and reinterpreted as a rock avalanche deposit the hillocks is a conspicuous cluster of small conical hills on the dart river floodplain the landform is protected under a local bylaw because of its identification as an outstanding example of a glacial kame deposit however the geological and geomorphological setting and the deposit morphology sedimentology and lithology suggest that it was formed by a large c 22 5 10 6 m 3 rock avalanche subsequent to glacial retreat and that the deposit temporarily dammed the dart river valley relative age dating evidence suggests that it is at least several hundred years old but younger than ca 7500 b p this work highlights the problem of paleoclimatic reconstructions using moraines as indicators of regional climate events despite similarities in form and in some cases sedimentology by applying an understanding of landslide initiation runout and depositional process we demonstrate that it is possible to distinguish the deposits produced by landslides from those produced by glacial deposition

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

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

cosmogenic nuclide chronology of pre last glacial maximum moraines at lago buenos aires 46 s argentina at lago buenos aires argentina 10 be 26 al and 40 ar 39 ar ages range from 190 000 to 109 000 yr for two moraines deposited prior to the last glaciation 23 000 16 000 yr ago two approaches maximum boulder ages assuming no erosion and the average age of all boulders and an erosion rate of 1 4 mm 10 3 yr both yield a common estimate age of 150 000 140 000 yr for the two moraines the erosion rate estimate derives from 10 be and 26 al concentrations in old erratics deposited on moraines that are n760 000 yr old on the basis of interbedded 40 ar 39 ar dated lavas the new cosmogenic ages indicate that a major glaciation during marine oxygen isotope stage 6 occurred in the mid latitude andes the next five youngest moraines correspond to stage 2 there is no preserved record of a glacial advance during stage 4 the distribution of dated boulders and their ages suggest that at least one major glaciation occurred between 760 000 and n200 000 yr ago the mid latitude patagonian glacial record which is well preserved because of low erosion rates indicates that during the last two glacial cycles major glaciations in the southern andes have been in phase with growth and decay of northern hemisphere ice sheets especially at the 100 000 yr periodicity thus glacial maxima are global in nature and are ultimately paced by small changes in northern hemisphere insolation d 2005 university of washington all rights reserved

the mis 3 maximum of the torres del paine and ultima esperanza ice lobes in patagonia and the pacing of southern mountain glaciation abstract the timing structure and termination of the last southern mountain glaciation and its forcing remains unclear most studies have focused on the global last glacial maximum lgm 26 5 19 ka time period which is just part of the extensive time frame within the last glacial period including marine isotope stages 3 and 4 understanding the glacial fluctuations throughout the glacial period is a prerequisite for uncovering the cause and climate mechanism driving southern glaciation and the interhemispheric linkages of climate change here we present an extensive n 65 cosmogenic 10be glacier chronology derived from moraine belts marking the pre global lgm extent of the former patagonian ice sheet in southernmost south america our results show the mountain ice sheet reached its maximum extent at 48 0 1 8 ka during the local lgm but attained just half this extent at 21 5 1 8 ka during the global lgm this finding supported by nearby glacier chronologies indicates that at orbital time scales the southern mid latitude glaciers fluctuated out of phase with northern hemisphere ice sheets at millennial time scales our data suggest that patagonian and new zealand glaciers advanced in unison with cold antarctic stadials and reductions in southern ocean sea surface temperatures this implies a southern middle latitudes wide millennial rhythm of climate change throughout the last glacial period linked to the north atlantic by the bipolar seesaw we suggest that winter insolation acting alongside other drivers such as the strength and or position of the southern westerlies controlled the extents of major southern mountain glaciers such as those in southernmost south america

holocene glacier fluctuations on the northern flank of cordillera darwin southernmost south america abstract records of past variability afford context for evaluating present day glacier behavior and for testing hypotheses of climate change here we use 69 radiocarbon dates of wood and other organic materials in association with glacial deposits to document the behavior of ventisqueros marinelli and brooks in cordillera darwin over the past 17 000 years recession from the last glacial maximum was early with most occurring prior to 17 000 yr bp any glacial resurgence during the antarctic cold reversal must have terminated within the bounds of holocene ice fluctuations by early holocene time ventisquero marinelli had retreated such that it was no more extensive than it was in ad 1992 we identify several subsequent glacier readvances but also note long periods of restricted ice extent particularly in the mid holocene there were times when holocene glaciers must have been smaller than at present our new record from marinelli shows similarities to other reconstructions of holocene glacier variation from southern south america such as at mt sarmiento and the south patagonian icefield suggesting an underlying climate signal the overall implication is of substantial early holocene deglaciation followed by repeated advances interspersed with periods of recession when ice extent was smaller than at present this general pattern of glacier behavior appears to differ from that of new zealand s southern alps and points to the value of a geographic spread of datasets to elucidate the pattern of southern hemisphere climate during the holocene

pleistocene water intrusions from the mediterranean and caspian seas into the black sea the hydrological balance of the black sea is governed by riverine input and by the exchange with the mediterranean sea a speleothem record from a cave in northern turkey that tracks the isotopic signature of black sea surface water suggests an open connection to the mediterranean sea in at least twelve periods in the past 670 000 years

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

cosmogenic 36cl dating of the foothills erratics train alberta canada the foothills erratics train of alberta was carried into place during coalescence between montane glaciers and the laurentide ice sheet its age has been controversial late wisconsinan and pre wisconsinan ages have been assigned to it cosmogenic 36 cl exposure dating was carried out on erratics over a 130 km segment of the erratics train seven of eight age determinations support emplacement during the late wisconsinan glaciation these ages eliminate the possibility of an ice free corridor during the last glacial maximum they are also consistent with the hypothesis that the laurentide ice sheet was the most extensive of all pleistocene continental ice sheets in western canada

evidence for a landslide origin of new zealand s waiho loop moraine the waiho loop moraine has been interpreted as evidence for younger dryas cooling in southern new zealand but recent dating and climatological studies have questioned this idea a detailed analysis of the sedimentology of the moraine suggests it was formed after a large landslide onto the franz josef glacier triggered a glacial surge independent of climate forcing

quaternary moraines vs catastrophic rock avalanches in the karakoram himalaya northern pakistan a history and conception of glacial events for the central karakoram himalaya proposed some 80 years ago by giotto dainelli are largely accepted today however certain deposits identified as terminal moraine complexes marking glacial episodes were actually emplaced by rock avalanches in the skardu and shigar intermontane basins of baltistan at least 15 rock avalanche events were previously mapped as moraine or till criteria used for distinguishing these catastrophic landslide deposits emphasize homogeneous lithology of rubble and matrix clast shape facies characteristics the large scale unity of emplacement and morphological relations to valley topography the deposits of three events at katzarah satpura and the north end of shigar valley have been reconstructed in detail thick supraglacial debris does not result in similar deposits extensive valley fills river terraces large sediment fans and lacustrine sediments formerly attributed to late glacial conditions are reinterpreted as postglacial events involving rock avalanches that interrupted fluvial development existing reconstructions of glaciations are left in doubt especially late glacial events in the central karakoram as are the roles assigned to karakoram main indus valley and western himalayan ice

assessing the age weathering correspondence of cosmogenic 21ne dated pleistocene surfaces by the schmidt hammer the schmidt hammer sh method is used to quantify the rock weathering degree and has been proposed as a relative dating tool terrestrial cosmogenic nuclide tcn methods provide absolute exposure ages for erosive surfaces few works combine both methods for surfaces older than the holocene we compare data obtained by both methods for c 150 ka bp glacial and fluvial erosive granite surfaces from northwest spain rebound values r have been firstly compared with the rock density to assess the correlation with the rock strength independently from influence of factors such as wetness and roughness in the r values for erosive glacial surfaces older than 100 ka r values are confined in a narrow range with no differences within errors stepped fluvial surfaces of 700 m to 70 m above present sea level show an inverse correspondence between tcn ages and r values although no age predictions can be done on the basis of the r values thus age inferences exclusively based on r values may not be realistic but sh studies could be a useful tool for selecting surfaces for tcn dating copyright 2009 john wiley sons ltd

techniques for measuring rock weathering application to a dated fan segment sequence in southern tunisia there are a number of techniques for estimating the amount of weathering a clast has undergone these usually have the objective of establishing an ordinal chronology of geomorphological surfaces or investigation of site specific conditions affecting weathering rates three such techniques are applied to a dated sequence of alluvial fan segments in southern tunisia two of these techniques depend on measuring surface roughness the micro roughness meter and a displacement approach and one uses the structural weakening of the rock fabric schmidt hammer the micro roughness meter enables calculation of standard deviation of surface height variation root mean square roughness and surface autocorrelation function of these techniques schmidt hammer rebound values standard deviation root mean square roughness and the displacement technique show systematic changes on the three fan segments which are statistically significant at the 0 05 level however the amount of variance in all datasets is very large indicating the need for caution in application of these techniques for relative dating 1998 john wiley sons ltd

modelling rock avalanche propagation onto glaciers abstract ice rock avalanches which occur in glacial environments are controlled by the presence of snow and ice in the moving material and by possible propagation onto icy basal surfaces all these factors contribute to enhancing the flow mobility mixing with ice and snow hampers block collisions and favours dense flow behaviour ice melting reduces granular friction by saturation of the basal material and fluidization effects propagating onto glaciers offers a smooth surface with low shear resistance this work is a review of the best documented ice rock avalanches and focuses on evaluating their mobility for hazard analysis purposes by providing a set of calibrated cases the rock avalanches have volumes ranging from 5 10 6 m 3 to 25 10 6 m 3 we replicate these events by using sph and fem numerical methods assuming frictional and voellmy basal rheologies the voellmy rheology best performs at replicating the landslide propagation among the back analyzed cases the frictional coefficient ranges in the interval 0 03 0 1 the turbulent coefficient within 1000 m s 2 2000 m s 2 the bulk basal friction angle ranges within 2 75 and 14 with values inversely related to event volumes forward selection of the basal friction angle based on event volume allows the replication of the mount cook ice rock avalanche predicting a maximum runout which is less than 4 larger than observed in the perspective of forward modelling large uncertainty is related to the reconstruction of the post event topographies particularly for the sliding surface mixing with ice and snow reduces basal friction proportionally to ice and snow content pure ice has a basal friction which is reduced by about 75 than basal friction of pure rock melting of ice during rock avalanche propagation has been evaluated for the sherman event the frictional heat generated at the glacier surface results in the melting of 86 2 5 9 kg m 2 which could have contributed to a minimum 20 35 10 reduction of the material friction angle through the sole pore pressure generation within a 40 and 20 cm thick shear layer respectively the largest uncertainty is related to the area of contact between rock and ice

degree of rock surface weathering as an indicator of ice sheet thickness along an east west transect across southern norway rock surface weathering as reflected by rock surface hardness and roughness was measured at six mountains along an east west transect across southern norway at most sites the results show significant differences in rock surface weathering across the autochthonous blockfield boundary suggesting that the areas above the boundary have been exposed to subaerial weathering for a considerably longer time span that the areas below the results are interpreted as reflecting the surface profile of an asymmetric west centred low gradient ice sheet

seismic stratigraphy and glacial cycles in the inland passages of the magallanes region of chile southernmost south america abstract we present results of a marine geophysical survey that imaged submarine sedimentary and geomorphic features of the main inland channels of the magallanes region of chile in southernmost south america this region holds a remarkable terrestrial and marine record of glacial variations in the closest landmass to antarctica we report evidence for grounded ice along the main channels associated with two ice lobes that flowed from cordillera darwin part of the austral andes into central estrecho de magallanes and seno almirantazgo multibeam data show drumlins and glacial lineations in whiteside channel the northern continuation of seno almirantazgo and iceberg plough marks in central estrecho de magallanes multichannel seismic data show a complex array of seismic facies interpreted as representing two main types of sedimentary units glacimarine sediments corresponding to glacial periods and pelagic sediments corresponding to interglacial periods we find that there are two interglacial glacial cycles represented in this marine sedimentary record chronologically 1 the youngest glacial unit corresponds to the last regional glaciation 31 18 ka 2 these passageways deglaciated with the retreat from regional glacial limit d 17 18 ka and 3 there is no marine sedimentary or morphological evidence that the magallanes glaciers readvanced into the main passageways during the antarctic cold reversal 14 13 ka these findings suggest that final deglaciation of southernmost south america was driven by the atmospheric and ocean warming that started 18 ka as recorded in antarctic ice core records and sea surface temperature proxies offshore the magallanes region

theory of glacial erosion transport and deposition as a consequence of subglacial sediment deformation a theory of erosion transport and deposition of unlithified sediments by glaciers is presented it predicts the large scale areal distribution of zones and rates of erosion and deposition in time and space through a complete glacial cycle together with the resultant intensity of large scale lincations drumlins which will be incised in the landscape the theory also predicts the dispersal patterns of subglacial lithologies together with the form of dispersal trains derived from distinctive sources and the vertical and horizontal distribution of lithologies within a till it predicts major erosional discontinuities within tills and the formation of boulder pavements it suggests that the dominant proportion of the lowland tills produced by pleistocene mid latitude ice sheets was generated by subglacial deformation and explains why they are predominantly fine grained the theory is based on an analysis of glacier dynamic processes and therefore can be used to infer the dynamic behaviour of former ice sheets from the distribution of tills and their lithologic composition

extensive mis 3 glaciation in southernmost patagonia revealed by cosmogenic nuclide dating of outwash sediments abstract the timing and extent of former glacial advances can demonstrate leads and lags during periods of climatic change and their forcing but this requires robust glacial chronologies in parts of southernmost patagonia dating pre global last glacial maximum glgm ice limits has proven difficult due to post deposition processes affecting the build up of cosmogenic nuclides in moraine boulders here we provide ages for the rio cullen and san sebastian glacial limits of the former bahia inutil san sebastian bi ssb ice lobe on tierra del fuego 53 54 s previously hypothesised to represent advances during marine isotope stages mis 12 and 10 respectively our approach uses cosmogenic 10be and 26al exposure dating but targets glacial outwash associated with these limits and uses depth profiles and surface cobble samples thereby accounting for surface deflation and inheritance the data reveal that the limits formed more recently than previously thought giving ages of 45 6 ka 139 9 14 3 for the rio cullen and 30 1 ka 45 6 23 1 for the san sebastian limits these dates indicate extensive glaciation in southern patagonia during mis 3 prior to the well constrained but much less extensive mis 2 glgm limit this suggests the pattern of ice advances in the region was different to northern patagonia with the terrestrial limits relating to the last glacial cycle rather than progressively less extensive glaciations over hundreds of thousands of years however the dates are consistent with mis 3 glaciation elsewhere in the southern mid latitudes and the combination of cooler summers and warmer winters with increased precipitation may have caused extensive glaciation prior to the glgm

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

rock surface roughness as an indicator of degree of rock surface weathering rock surface weathering often leads to increased rock surface roughness but roughness has proved difficult to quantify several instruments are available for micro mapping and recording rock surface profiles but the most appropriate for most purposes is the simple profile gauge short profiles can be recorded quickly and accurately a range of roughness indices has been proposed in other areas of geomorphology and their efficacy as measures of roughness at scales of interest in studies of weathering is assessed some are too complex or labour intensive and others are too sensitive to the scale of roughness to provide reliable measures of magnitude the most appropriate indicator of both the scale and magnitude of roughness is the standard deviation of the differences between height values at a range of set horizontal intervals along a profile the deviogram varying the measurement interval records roughness at different scales a regression approach root mean square roughness provides a reliable measure of the magnitude of roughness at the maximum scale present three case studies confirm the efficacy of these approaches to studies of weathering of different rocks in different environments software is supplied which automates the calculation of roughness indices from gauge profiles

depositional framework and hydrocarbon resources of the early miocene fleming episode northwest gulf coast basin abstract the fleming group and its basinward equivalents constitute deposits of a major cenozoic depositional episode of the northern gulf coast basin the facies complex is bounded above by the amphistegina b shale and below by the anahuac shale initially early miocene oakville progradation built across the broad submerged shelf platform constructed during the earlier frio depositional episode at the frio paleocontinental margin the rate of outbuilding slowed as large scale growth faulting created a narrow early miocene expansion zone the later part of the episode was characterized by a stable to retreating shoreline and consequent aggradational to retrogradational deposition lagarto formation the lower miocene depositional framework includes in south texas the santa cruz fluvial system and the north padre delta system the bedload fluvial complex fed a wave dominated delta which constructed a broadly convex deltaic headland across the foundered frio norias delta system extensive wave reworking and longshore transport of sand and mud nourished a broad barrier lagoon and strandplain complex that extended along the central and much of the northeastern texas coast this well known matagorda barrier strandplain system was bounded updip by a coastal plain traversed by numerous small intrabasinal streams near the present sabine river westernmost deposits of a continental scale mixed load fluvial and equivalent delta system extend beneath the texas coastal plain and shelf from the miocene depocenter in louisiana here the initial phase of early miocene progradation was also complicated by the incision and filling of numerous submarine gorges lower miocene reservoirs have produced nearly 500 million tonnes 4 billion barrels of oil equivalent boe of hydrocarbons from nine identified plays in the texas coastal plain and shelf the most prolific play the salt domes of the houston embayment accounts for nearly all the oil and more than two thirds of the total production from the sequence four offshore plays offer greatest room for discovery of substantial new reserves primarily of gas to date however the yield per volume of reservoir sandstone for miocene plays remains low relative to more prolific units such as the frio formation

cosmogenic 36cl dating of the maximum limit of the laurentide ice sheet in southwestern alberta cosmogenic 36cl ages were determined on 11 glacial erratics from the summits of porcupine hills and cloudy ridge waterton valley and the foothills south of cardston alberta these erratics were derived from the canadian shield and the rocky mountains of the waterton area they were laid down by 1 the most extensive advance of a canadian shield centred continental ice sheet into this region stratigraphically oldest glacial deposits 2 a montane glacial advance from the waterton valley stratigraphically intermediate glacial deposits and 3 an advance of continental glacial ice that overrode deposits of the intermediate age montane advance zero erosion rate 36cl ages of the erratics uncorrected for snow cover range between about 12 and 18 ka they support the hypothesis that the laurentide ice sheet reached farther into the southwestern foothills than did all the previous continental ice sheets

comparison between holocene and marine isotope stage 11 sea level histories the exceptionally long interglacial warm period known as marine isotope stage 11 mis 11 428 397 ky ago vs ky vs kyr is often considered as a potential analogue for future climate development in the absence of human influence we use a new high resolution sea level record a globally integrated ice volume signal to compare mis 11 and the current interglacial holocene it is found that sea level rise into both interglacials started over similar timescales relative to the respective insolation increases and progressed up to 50 m at similar rates of 1 0 1 2 m per century subsequent weak insolation changes anomalously prolonged the mis11 deglaciation over more than 20 ky the main sea level highstand was achieved at the second mis 11 insolation maximum with a timing closely equivalent to that of the holocene highstand compared to its single insolation maximum consequently while mis 11 was an exceptionally long period of interglacial warmth its ice volume minimum sea level highstand lasted less than 10 ky which is similar to the duration of other major interglacials comparison of the ends of mis 11 and the holocene based on timings relative to their respective maxima in mean 21 june insolation at 65 n suggests that the end of holocene conditions might have been expected 2 0 2 5 ky ago instead interglacial conditions have continued with co2 temperature and sea level remaining high or increasing this apparent discrepancy highlights the need to consider that a comparisons may need to focus on other orbital control indices in which case the discrepancy can vanish and or b the feedback mechanisms that dominate the planetary energy balance may have become decoupled from insolation during the past 2millennia

the sedimentology and geomorphology of rock avalanche deposits on glaciers this article describes and compares the deposits of four large landslides on two glaciers in alaska using field mapping and remote sensing digital image analysis is used to compare the sedimentological characteristics of nearly 200 000 individual surface blocks deposited by three landslides at black rapids glacier in 2002 the debris sheets of one of the three landslides on black rapids glacier and a landslide emplaced on sherman glacier in 1964 are also investigated the three landslides on black rapids glacier have undergone little post depositional modification by glacier flow whereas the sherman glacier landslide has been transported supraglacially up to ca 1k m over the past 46 years the three debris sheets on black rapids glacier have coarse blocky rims at their distal edges and all four debris sheets have longitudinal flowbands characterized by differences in texture and produced by shearing within the moving debris elongated blocks are parallel to flow except at the perimeter of the debris sheets where they are aligned more perpendicular to flow blocks on the sherman glacier debris sheet have been reoriented by glacier flow the matrix shows no systematic differences with depth or distance from the source however it appears to become coarser over a time scale of decades due to weathering

on the origin of the bosphorus abstract the palaeozoic upper cretaceous basement palaeomorphology of the bosphorus the strait of istanbul bears the evidence of a valley of a palaeostream running to the black sea in the north a palaeobasin deeper than 160 m opening to the sea of marmara in the south and a barrier between these two features this suggest that the northern part of the bosphorus was formed mainly by fluvial activity whereas the southern part developed as a basin by faulting the recent sediment thickness exceeds 130 m in the basin indicating that the southern part of the bosphorus was once essentially depositional rather than an erosional the present form of the bosphorus was established in holocene time by the connection of the basin in the south with the stream in the north the barrier and the stream valley in the north have been deepened by erosion and faulting to form a strait connecting the black sea and the mediterranean

pycnocline and deep mixing in the black sea stable isotope and transient tracer measurements abstract the peculiar mixing processes at the pycnocline and deep regions of the black sea are reviewed in addition to the wind stirring and convective mixing active in the upper pycnocline the other important mechanism that results in limited ventilation of the anoxic waters of the black sea is the mediterranean dense water inflow from the bosphorus modified by the entrainment of surface and intermediate waters introduced into the interior through double diffusive intrusions this inflow aided by the surface ekman flux divergence boundary processes and internal wave breaking is the main mechanism for the mixing and renewal of the sub pycnocline waters in the black sea interior a review of these mixing processes is complemented by results from isotope measurements with improved accuracy and reduced noise compared to earlier experiments measurements of the stable isotopes oxygen 18 18 o and deuterium 2 h confirm the origin of the water masses in the black sea and in the turkish straits including the sea of marmara to be a continuous mixture with variable fractions of salty mediterranean waters with inflowing fresh waters tritium 3 h measurements confirm very little penetration of the transient signal to the sub pycnocline and deep waters of the black sea in comparison to the better ventilated mediterranean waters filling the lower layer of the marmara sea the comparison of stable and transient tracer isotopes shows the effects of fresh waters originating from the north western shelf and the difference between the renewal mechanisms of the marmara and black seas as well as those between the upper and lower pycnocline of the black sea

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

large rock avalanches triggered by the m 7 9 denali fault alaska earthquake of 3 november 2002 the moment magnitude m 7 9 denali fault alaska earthquake of 3 november 2002 triggered thousands of landslides primarily rock falls and rock slides that ranged in volume from rock falls of a few cubic meters to rock avalanches having volumes as great as 20 10 6 m 3 the pattern of landsliding was unusual the number and concentration of triggered slides was much less than expected for an earthquake of this magnitude and the landslides were concentrated in a narrow zone about 30 km wide that straddled the fault rupture zone over its entire 300 km length despite the overall sparse landslide concentration the earthquake triggered several large rock avalanches that clustered along the western third of the rupture zone where acceleration levels and ground shaking frequencies are thought to have been the highest inferences about near field strong shaking characteristics drawn from interpretation of the landslide distribution are strikingly consistent with results of recent inversion modeling that indicate that high frequency energy generation was greatest in the western part of the fault rupture zone and decreased markedly to the east d 2005 elsevier b v all rights reserved

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

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

the effects of the north anatolian fault zone on the latest connection between black sea and sea of marmara abstract the development of the strait of istanbul is also one of the principal results of the tectonics which led to the evolution of the north anatolian fault zone nafz in the marmara region 3 7 ma ago high resolution seismic profiles from the marmara entrance of the strait of istanbul show a folding which occurred after the deposition of the parallel reflected tyrrhenian sediments over the tyrrhenian strata a fondoform zone of a deltaic sequence and marine sediments of the latest sea level rising are present these sediments also display syn depositional folding this situation implies that a local compressional stress field was created over the area probably since the wurm glacial age this recent variation of the tectonic regime in the northern shelf of the sea of marmara may indicate a significant change in the development of the nafz through the sea of marmara this variation of evolution of the nafz affected the latest development of the strait of istanbul via clockwise rotation of the istanbul and kocaeli peninsulas by right lateral shearing between two zone bounding faults this rotation has led to the development of nne ssw left lateral faults in the strait of istanbul and local compressional and tensional areas explaining the compressional structures seen in the southern entrance of the strait of istanbul therefore the latest mediterranean black sea connection was established by means of the sufficient deepening of the bosphorus channel by a variation in the evolution of nafz through the sea of marmara

climatostratigraphic scheme of the black sea pleistocene and its correlation with the oxygen isotope scale and glacial events abstract new evidence from the asov sea black sea region shows that after the cobb mountain magnetic event 1 1 myr there were 8 saline water events with mediterranean molluscs penetrating into the asov sea five times farther than the western manych strait and 7 or 10 cold freshwater events during the freshening phase the caspian sea molluscan fauna penetrated into the black sea each time the caspian mollusc assemblage was characterized by a new species of didacna thus some 18 20 bioclimatostratigraphic units can be distinguished in the asov sea black sea section for the last 1 myr their numerical age is estimated by some dozen thermoluminescence dates and 12 magnetic polarity datum planes the karangatian s lato corresponds to the interval 300 000 50 000 yr the uzunlarian to 580 000 300 000 yr and the chaudian to 1 100 000 600 000 yr the karangatian and tyrrhenian marine terraces correspond to marine isotope stages 5 and 7 the uzunlarian and milazzian to stages 11 15 and the chaudian and sicilian to stages 16 28 the number and ages of glacial interglacial cycles in continental europe are identical to the climatic cycles in the black sea and mediterranean

regional mid pleistocene glaciation in central patagonia abstract southern south america contains a glacial geomorphological record that spans the past million years and has the potential to provide palaeoclimate information for several glacial periods in earth s history in central patagonia two major outlet glaciers of the former patagonian ice sheet carved deep basins 50 km wide and extending over 100 km into the andean plain east of the mountain front a succession of nested glacial moraines offers the possibility of determining when the ice lobes advanced and whether such advances occurred synchronously the existing chronology which was obtained using different methods in each valley indicates the penultimate moraines differ in age by a full glacial cycle here we test this hypothesis further using a uniform methodology that combines cosmogenic nuclide ages from moraine boulders moraine cobbles and outwash cobbles 10 be concentrations in eighteen outwash cobbles from the moreno outwash terrace in the lago buenos aires valley yield surface exposure ages of 169 269 ka we find 10 be inheritance is low and therefore use the oldest surface cobbles to date the deposit at 260 270 ka which is indistinguishable from the age obtained in the neighbouring lago pueyrredon valley this suggests a regionally significant glaciation during marine isotope stage 8 and broad interhemispheric synchrony of glacial maxima during the mid to late pleistocene finally we find the dated outwash terrace is 70 100 ka older than the associated moraines on the basis of geomorphological observations we suggest this difference can be explained by exhumation of moraine boulders

controversy over the great flood hypotheses in the black sea in light of geological paleontological and archaeological evidence abstract legends describing a great flood are found in the narratives of several world religions and the biblical account of noah s flood is the surviving heir to several versions of the ancient mesopotamian flood myth recently the story of the biblical deluge was connected to the black sea together with the suggestion that the story s pre mesopotamian origins might be found in the pontic basin ryan w b f pitman iii w c 1998 noah s flood the new scientific discoveries about the event that changed history simon and schuster new york based on the significance of this flood epic in the judeo christian tradition popular interest surged following publication of the idea currently two great flood scenarios have been proposed for the black sea 1 an early holocene event caused by catastrophic mediterranean inflow at 7 2 ky bp initial hypothesis of ryan et al 1997 an abrupt drowning of the black sea shelf marine geology 138 119 126 or 8 4 ky bp modified hypothesis of ryan et al 2003 catastrophic flooding of the black sea annual review of earth and planetary science 31 525 554 and 2 a late pleistocene event brought on by caspian influx between 16 and 13 ky bp chepalyga a l 2003 late glacial great flood in the black sea and caspian sea gsa annual meeting and exposition 2 5 november 2003 seattle usa p 460 both hypotheses claim that the massive inundations of the black sea basin and ensuing large scale environmental changes had a profound impact on prehistoric human societies of the surrounding areas and both propose that the event formed the basis for the biblical great flood legend this paper attempts to determine whether the preponderance of existing evidence sustains support for these great floods in the evolution of the black sea based upon established geological and paleontological data it finds that the late pleistocene inundation was intense and substantial whereas the early holocene sea level rise was not between 16 and 13 ky bp the late neoeuxinian lake the late pleistocene water body in the pontic basin pre dating the black sea increased rapidly from 14 to 50 m below the present level of the black sea then rose gradually to 20 m by about 11 ky bp at 11 10 ky bp the younger dryas it dropped to 50 m when the black sea re connected with the sea of marmara at about 9 5 ky bp inflowing mediterranean water increased the black sea level very gradually up to 20 m and in so doing it raised the salinity of the basin and brought in the first wave of mediterranean immigrants these data indicate no major drawdown of the black sea after the younger dryas and they do not provide evidence for any catastrophic flooding of the black sea in the early holocene in addition available archaeological and paleoenvironmental evidence from the pontic region reveal no recognizable changes in population dynamics between 14 and 6 ky bp that could be linked to an inundation of large magnitude dolukhanov p shilik k 2006 environment sea level changes and human migrations in the northern pontic area during late pleistocene and holocene times in yanko hombach v gilbert a s panin n dolukhanov p m eds the black sea flood question changes in coastline climate and human settlement springer dordrecht pp 297 318 stanko v n 2006 fluctuations in the level of the black sea and mesolithic settlement of the northern pontic area in yanko hombach v gilbert a s panin n dolukhanov p m eds the black sea flood question changes in coastline climate and human settlement springer dordrecht pp 371 385 more specifically mesolithic and early neolithic archaeological data in southeastern europe and ukraine give no indications of shifts in human subsistence or other behavior at the time of the proposed catastrophic flood in the early holocene anthony d 2006 pontic caspian mesolithic and early neolithic societies at the time of the black sea flood a small audience and small effects in yanko hombach v gilbert a s panin n dolukhanov p m eds the black sea flood question changes in coastline climate and human settlement springer dordrecht pp 345 370 dergachev and dolukhanov 2006 the neolithization of the north pontic area and the balkans in the context of the black sea floods in yanko hombach v gilbert a s panin n dolukhanov p m eds the black sea flood question changes in coastline climate and human settlement springer dordrecht pp 489 514

climatic and environmental controls on speleothem oxygen isotope values variations in speleothem oxygen isotope values d 18 o result from a complicated interplay of environmental controls and processes in the ocean atmosphere soil zone epikarst and cave system as such the controls on speleothem d 18 o values are extremely complex an understanding of the processes that control equilibrium and kinetic fractionation of oxygen isotopes in water and carbonate species is essential for the proper interpretation of speleothem d 18 o as paleoclimate and paleoenvironmental proxies and is best complemented by study of site specific cave processes such as infiltration flow routing drip seasonality and saturation state and cave microclimate among others this review is a process based summary of the multiple controls on d 18 o in the atmosphere soil epikarst and speleothem calcite illustrated with case studies primary controls of d 18 o in the atmosphere include temperature and relative humidity through their role in the multiple isotope effects variability and modifications of water d 18 o values in the soil and epikarst zones are dominated by evaporation mixing and infiltration of source waters the isotopically effective recharge into a cave system consists of those waters that participate in precipitation of caco3 resulting in calcite deposition rates which may be biased to time periods with optimal dripwater saturation state recent modeling experimental and observational data yield insight into the significance of kinetic fractionation between dissolved carbonate phases and solid caco3 and have implications for the hendy test to assist interpretation of speleothem d 18 o time series quantitative and semi quantitative d 18 o climate calibrations are discussed with an emphasis on some of the difficulties inherent in using modern spatial and temporal isotope gradients to interpret speleothems as paleoclimate proxy records finally several case studies of globally significant speleothem paleoclimate records are discussed that show the utility of d 18 o to reconstruct past climate

middle pleistocene glaciations of the russian north abstract geological data on the pre eemian glaciations of northern russia including the latest results by the russian norwegian pechora project are synthesized in order to present evidence for comparison with other early glaciations around the arctic the bulk of evidence indicates that arctic and subarctic regions of european russia of western and central siberia during the middle pleistocene were at least 4 times covered by large ice sheets which advanced mainly from the shelf ice domes partly from fennoscandia and the putorana plateau ice accumulations in the ural mountains were insignificant and did not form any noticeable ice dispersal centres unlike the classical glaciated areas ice sheets of northern russia acted mainly on a soft perennially frozen substrate which was heavily glacitectonised the middle pleistocene ice sheets were much larger than the weichselian ones the fennoscandian ice dispersal centre was most active in northern european russia during the penultimate glaciation ois 6 when shelf centred ice domes were relatively weaker larger continental ice sheets were formed in preceding ice ages when kara sea ice dispersal centre dominated the lowland ice sheets reached their maximum extent at different stages from cromerian don glaciation in european russia to ois 8 in west siberia therefore the maximum ice limit is time transgressive in northern russia

field estimate of paleoseismic slip on a normal fault using the schmidt hammer and terrestrial lidar methods and application to the hebgen fault montana usa