distribution and glaciological implications of relict surfaces on the ultevis plateau northwestern sweden distribution and glaciological implications of relictsurfaces on the ultevis plateau northwestern sweden

relict non glacial surfaces in formerly glaciated landscapes abstract relict non glacial surfaces occur within many formerly glaciated landscapes and contain important information on past surface processes and long term landscape evolution relict non glacial surfaces are distinguishable from glacial surfaces by large scale morphologies including rounded summits fluvial valleys and cryoplanation terraces and pediments and the presence of tors blockfields and or saprolites preservation during glaciation occurs either through coverage by non erosive cold based ice or as nunataks although surface morphologies and denudation rates indicate a continuous non glacial surface history since preglacial times relict non glacial surfaces are dynamic features that have evolved during the quaternary depending on spatial variables such as lithology slope regolith depth and the abundance of fine matrix and water some surfaces are denuding very slowly while others display more rapid denudation high spatial variability in denudation rates results in changing surface morphologies over time denudation rates also display high temporal variability with much surface evolution having perhaps occurred soon after the initial onset of glaciation or during paraglacial phases while some parts of non glacial landscapes are currently active others may be largely inactive relicts of past higher energy regimes although non glacial surfaces are dynamic much remains to be determined regarding surface denudation rates and the magnitude of morphological changes over time

strike slip tectonics during the neoproterozoic cambrian assembly of east gondwana evidence from a newly discovered microcontinent in the indian ocean batavia knoll the first dredge samples recovered from the batavia knoll in the eastern indian ocean demonstrate it is a rifted continental fragment that now lies submerged in 2 km of water between the perth abyssal plain and wharton basin 1600 km offshore western australia this knoll is the second microcontinent to have been discovered in this region lying 180 km to the ne of gulden draak knoll both knolls rifted from the indian margin at c 104 101 ma during the breakup of east gondwana dredged rocks include granite granodiorite charnockite and quartz rich pegmatite preserving igneous microstructure and biotite schlieren the composite nature of many samples suggests derivation from a felsic igneous complex this basement is at least partly covered by late cretaceous sedimentary strata zircon grains from five representative granitoid samples primarily display modified oscillatory zoning and u pb data that spread along concordia over 50 70 m y suggesting protracted magmatism and pb loss during the latest neoproterozoic early cambrian c 580 530 ma despite the span in u pb zircon ages the primary igneous populations exhibit a relatively narrow range of initial hf isotopic ratios hfi 0 281290 0 281814 ehfi 41 40 to 23 32 this evolved nature of the hf signature suggests derivation of melts from ancient crust tdm2 4 05 2 92 ga with very limited juvenile input plate models based on sparse paleomagnetic data imply significant relative motion between india and australia during the late neoproterozoic cambrian we suggest the new isotopic data from the batavia knoll granitic rocks coupled with other regional geological constraints are consistent with magmatic intrusion and subsequent disturbance of u pb systems along a late neoproterozoic cambrian sinistral strike slip margin related to gondwana assembly

upper crustal stress and seismotectonics of the garhwal himalaya using small to moderate earthquakes implications to the local structures and free fluids abstract the work presents new focal mechanism data of small to moderate 3 0 ml 5 0 upper crustal earthquakes for the garhwal himalaya from a local seismic network installed in july 2007 majority of the epicenters of these earthquakes are located close to the main central thrust mct zone we retrieved moment tensor mt solutions of 26 earthquakes by waveform inversion the mt results and 11 small to moderate earthquakes from the published records are used for stress inversions the mt solutions reveal dominatingly thrust mechanisms with few strike slip earthquakes near chamoli the seismic cross sections illustrate that these earthquakes are located around the mid crustal ramp mcr in the detachment the optimally oriented faults from stress inversions suggest that the seismogenic fault in this region is similar to a fault plane having dip angle between 12 and 25 degrees which is compatible with the dip angle of the mcr 16 in this region p axes and the maximum horizontal compressive stress are ne sw oriented the direction of the relative motion of indian plate with respect to the eurasian plate the friction coefficient estimated from stress inversions show that the chamoli region having low friction in comparison to the overall values the free fluids trapped beneath the detachment are penetrating into the local faults hence decreasing the frictional strength and altering the prevailing stress conditions of the surroundings the present study reveals that the mcr structure is seismogenically active and producing the small moderate earthquakes in the region while the mct is probably dormant at present

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

catastrophic ice shelf breakup as the source of heinrich event icebergs 1 heinrich layers of the glacial north atlantic record abrupt widespread iceberg rafting of detrital carbonate and other lithic material at the extreme cold culminations of bond climate cycles both internal glaciologic and external climate forcings have been proposed here we suggest an explanation for the iceberg release that encompasses external climate forcing on the basis of a new glaciological process recently witnessed along the antarctic peninsula rapid disintegrations of fringing ice shelves induced by climate controlled meltwater infilling of surface crevasses we postulate that peripheral ice shelves formed along the eastern canadian seaboard during extreme cold conditions would be vulnerable to sudden climate driven disintegration during any climate amelioration ice shelf disintegration then would be the source of heinrich event icebergs

cirques have growth spurts during deglacial and interglacial periods evidence from 10be and 26al nuclide inventories in the central and eastern pyrenees cirques are emblematic landforms of alpine landscapes the statistical distribution of cirque floor elevations is used to infer glacial equilibrium line altitude and the age of their frontal moraines for reconstructing glacial chronologies very few studies however have sought to measure cirque floor and supraglacial ridgetop bedrock downwearing rates in order to confront these denudation estimates with theoretical models of quaternary mountain landscape evolution here we use 10 be nuclide samples n 36 from moraines bedrock steps and supraglacial ridgetops among a population of cirques in the east central pyrenees in order to quantify denudation in the landscape and detect whether the mountain topography bears any relevance to the glacial buzzsaw hypothesis minimum exposure ages meas obtained for a succession of moraines spanning the oldest dryas to the holocene produced a deglaciation chronology for three different pyrenean ranges maladeta bassies and carlit based on a series of corrections calibrations and chronostratigraphic tuning procedures meas on ice polished bedrock exposures were further used to model denudation depths at nested timescales during the wurm the younger dryas and the holocene results show that subglacial cirque floor denudation was lower during glacial periods wurm 10 mm ka than during deglacial and interglacial periods tens to hundreds of mm ka the relative inefficiency of glacial denudation in the cirque zone during the wurm would have resulted from i cold based and or ii low gradient glaciers situated in the upper reaches of the icefield and or from iii glacier load starvation because of arrested clast supply from supraglacial rockslopes situated in the permafrost zone denudation peaked during the younger dryas and holocene glacial advances a time when cirque glaciers became steeper warmer based and when frost cracking weakened supraglacial ridgetops thus enhancing sub glacial erosion by providing debris to the sliding glacier base cirques therefore grow faster during more temperate periods of cirque glaciation than under full glacial conditions another key finding was the very low rates of ridgetop lowering averaged over the wurm and holocene 10 25 mm ka a comparison of the denudation rates obtained from the cirque zone with regional estimates of crustal uplift indicates that the alpine topography is not in a steady state the low intensity of glacial denudation failed to bring the topography to a buzzsaw equilibrium state

tectonic denudation and topographic development in the spanish sierra nevada 1 the denudation history of the rapidly uplifting western part of the spanish sierra nevada was assessed using apatite fission track aft ages and 10be analyses of bedrock and fluvial sediments major contrasts in the denudation history are recorded within the 27 km2 rio torrente catchment upland areas are characterized by low relief low slope angles and locally the preservation of shallow marine sediments which have experienced 2 km of denudation since circa 4 ma the minimum denudation rates of 0 4 mm yr 1 derived from aft also contrast with the slow medium term 104 years erosion rates 0 044 0 015 mm yr 1 estimated from 10be measurements at high elevations the local medium long term contrasts in denudation rates within the high sierra nevada indicate that much of the unroofing occurs by tectonic denudation on flat lying detachments in lower elevation parts of the catchment rapid river incision coupled to rock uplift has produced 1 6 km of relief implying that the rivers and adjacent hillslopes close to the edge of the orogen are sensitive to normal fault driven changes in base level however these changes are not transmitted into the low relief slowly eroding upland areas thus the core of the mountain range continues to increase in elevation until the limits of crustal strength are reached and denudation is initiated along planes of structural weakness we propose that this form of tectonic denudation provides an effective limit to relief in young orogens

10 be data from meltwater channels suggest that jameson land east greenland was ice covered during the last glacial maximum along the northeast greenland continental margin bedrock on interfjord plateaus is highly weathered whereas rock surfaces in fjord troughs are characterized by glacial scour based on the intense bedrock weathering and lack of glacial deposits from the last glaciation interfjord plateaus have long been thought to be ice free throughout the last glacial maximum lgm in recent years there is growing evidence from shelf and fjord settings that the northeast greenland continental margin was more extensively glaciated during the lgm than previously thought however little is still known from interfjord settings we present cosmogenic 10be data from meltwater channels and weathered sandstone outcrops on jameson land an interfjord highland north of scoresby sund the mean exposure age of samples from channel beds n 3 constrains on the onset of deglaciation on interior jameson land to 18 5 1 3 21 4 1 9 ka for erosion conditions of 0 10 mm ka respectively this finding adds to growing evidence that the northeast greenland continental margin was more heavily glaciated during the lgm than previously thought

timing of terminal pleistocene deglaciation at high elevations in southern and central british columbia constrained by 10be exposure dating abstract the cordilleran ice sheet cis covered most of british columbia and southern yukon territory at the local last glacial maximum llgm during marine oxygen isotope stage 2 however its subsequent demise is not well understood particularly at high elevations east of its ocean terminating margin we present 10be exposure ages from two high elevation sites in southern and central british columbia that help constrain the time of initial deglaciation at these sites we sampled granodiorite erratics at elevations of 2126 2230 m a s l in the marble range and 1608 1785 m a s l in the telkwa range at the western margin of the interior plateau the erratics at both sites are near ice marginal meltwater channels that delineate the local ice surface slope and thus the configuration of the ice sheet during deglaciation the locations of the erratics and their relations to meltwater channels ensure that the resulting 10be ages date cis deglaciation and not the retreat of local montane glaciers our sample sites emerged above the surface of the cis as its divide migrated westward from the interior plateau to the axis of the coast mountains two of the four samples from the summit area of the marble range yielded apparent exposure ages of 14 0 0 7 and 15 2 0 8 ka these ages are 1 8 3 0 ka younger than the well established llgm age of ca 17 ka for the puget lobe of the cis in washington state they are 1 7 ka younger than the llgm age for the puget lobe if a snow shielding correction to their uncertainty weighted mean age is applied the other two samples yielded much older apparent exposure ages 20 6 1 4 and 33 0 1 5 ka indicating the presence of inherited isotopes four samples collected from the summit area of the telkwa range in the hazelton mountains yielded well clustered apparent exposure ages of 10 1 0 6 10 2 0 7 10 4 0 5 and 11 5 1 1 ka significant present day snow cover introduces a large uncertainty in the apparent exposure ages from this site a snow shielding correction based on present day snow cover data increases the uncertainty weighted mean exposure age of the telkwa range erratics to 12 4 0 7 ka consistent with deglacial 14c ages from areas near sea level to the west our exposure ages show a thinning of the southern portion of the cis shortly after the llgm and persistence of a remnant mountain ice cap in the central coast mountains into the younger dryas chronozone our data also show that the summit area of the marble range was ice covered during the llgm the presence of an ice body of considerable dimension in north central british columbia until or possibly even after the younger dryas highlights the need for geomorphological and geochronological studies of the ice dispersal centre over the skeena mountains in northwest british columbia and the need for better understanding of the response of the cis to lateglacial climate fluctuations

provinciality of ice rafting in the north atlantic application of 40ar 39ar dating of individual ice rafted hornblende grains the history of the northern hemisphere ice sheets is an important aspect of the paleoclimate system the layered record of ice rafted detritus ird and other climate indicators preserved in deep sea sediment cores provides the potential to unravel the sequences of events surrounding important intervals during the last glacial cycle the work presented here is a first step in the goal to characterize the composition of glacially derived detritus in proximal locations near the laurentide greenland and scandinavian ice sheets the intent of this paper is to highlight the potential for using provenance studies of ird in marine sediments in particular 40 ar 39 ar ages of hornblende grains in this case to trace the history of ice sheets in the past published work on land and at the glacial marine margins has mapped the margins of important ice sheets including the locations where glacial ice extended to the shelf slope break at these shelf slope break locations large glacial marine fans termed trough mouth fans tmf are known to occur in about 25 locations around the north atlantic nordic arctic oceans by characterizing the sediment sources in these tmfs the major ird components for deposition in deep sea sediment cores are documented although there is substantial overlapin the geological histories of the continental sources around the north atlantic there are also some systematic variations that will allow distinction of different sources realization of the full potential awaits characterizing the sources with multiple tracers as well as sedimentological studies and documenting the geographic pattern of dispersal in marine sediments within small time windows r 2002 published by elsevier science ltd

role of in situ cosmogenic nuclides 10be and 26al in the study of diverse geomorphic processes the central premises of applications of the in situ cosmogenic dating method for studying specific problems in geomorphology are outlined for simple and complex exposure settings in the light of these general models we discuss the information that can be derived about geomorphic processes utilizing concentrations of in situ produced cosmogenic radionuclides 10be half life 1 5 ma and 26a1 half life 0 7 ma in a variety of geomorphic contexts glacial polish and tills meteorite impact craters alluvial fans paleo beach ridges marine terraces sand dunes and bedrock slopes we also compare 10be 26al data with results obtained by other dating methods we conclude that the technique of measuring in situ cosmic ray produced nuclides holds promise for quantitative studies of processes and time scales in a wide range of geomorphological problems

a relict landscape in the centre of fennoscandian glaciation geomorphological evidence of minimal quaternary glacial erosion abstract the parkajoki area in northeastern sweden is situated near the central area of fennoscandian glaciation despite its location the area is dominated by landforms induced by subaerial weathering and erosion processes such as well developed tors and associated saprolites boulder fields and boulder depressions the glacial geomorphology is dominated by lateral and proglacial meltwater channels subglacial imprints indicative of thawed bed conditions and reshaping by glacier sliding e g fluting drumlins striae are lacking hence most of the landscape still exhibits a preglacial appearance because of its location near the central area of glaciation we attribute preservation to frozen bed conditions of overriding ice sheets the widespread distribution of well developed tors and boulder fields and the degree of chemical weathering of the bedrock indicate that the area has been protected from glacial erosion during all glacial cycles since ice sheet initiation in the late cenozoic unlike most other areas with tors in glaciated regions the parkajoki area is uniquely situated in the lowlands at 150 400 m a s l moreover this relict landscape is surrounded by glacial landscapes including drumlins ribbed moraine and eskers of varying age and at similar elevation hence topographical reasons for this area being persistently cold based cannot be invoked by inference we conclude that strain heat release never managed to cancel the initial subglacial permafrost conditions we attribute this to divergent ice flow towards the convex outline of the ice sheet margin during deglaciations and to the relative roughness of the area compared to its surroundings the implication is that to explain preservation throughout the quaternary all large scale glaciations must have had a similar evolution concerning ice sheet configuration and internal dynamics as the last glaciation for which good constraints on evolution and outline are available

pliocene pleistocene ice rafting history and cyclicity in the nordic seas during the last 3 5 myr a continuous 3 5 myr ird record was produced from ocean drilling program odp site 907 a timescale based on magnetic polarity chrons oxygen isotope stratigraphy for the last 1myr and orbital tuning was developed the record documents a stepwise inception of large scale glacial cycles in the nordic seas region the first being a marked expansion of the greenland ice sheet at 3 3 ma a second step occurred at 2 74 ma by an expansion of large scale ice sheets in the northern hemisphere ice sheet variability around the nordic seas was tightly coupled to global ice volume over the past 3 3 myr between 3 and 1 ma most of the variance of the ird signal is in the 41 kyr band whereas the last 1 myr is characterized by stronger 100 kyr variance the gamma ray porosity evaluator grape density record is closely linked with ird variations and documents sub orbital variability resembling the late quaternary heinrich bond cycles

cosmogenic nuclide exposure ages along a vertical transect in western norway implications for the height of the fennoscandian ice sheet 10 be and 26 al exposure ages for bedrock samples from a vertical transect at skala in western norway provide new constraints on the history of the fennoscandian ice sheet the weathered bedrock surface autochthonous block field mantling the summit of skala has an exposure age of 55 ka suggesting that this surface formed before the last glacial maximum 18 14 c ka or 21 calendar ka the block field is truncated by a glacial trimline at 1660 m above sea level glaciated bedrock below the trimline has an exposure age of 26 21 ka the range depends on assumptions about erosion rate ice therefore receded from this altitude at about the time of the last glacial maximum the 10 be age for bedrock immediately below a second lower trimline at skala suggests a glacial advance or stillstand at 18 13 ka consistent with previously documented readvances or stillstands at the western and southern margins of the ice sheet

erosion rates in fennoscandia during the past million years abstract the widespread existence of cosmogenic nuclides accumulated in bedrock prior to the last glaciation demonstrates the limited erosional efficacy of the most recent fennoscandian and laurentide ice sheets yet the deeper history of erosion in these landscapes repeatedly blanketed by ice remains essentially unknown here we present the first comprehensive ice sheet wide analysis of cosmogenic 10be data n 953 from the fennoscandian landscape we find 64 of all sampled bedrock surfaces contain 10be inheritance including 85 of blockfields and tors and 50 of ice carved terrain in addition to 27 of ice transported boulders recent ice sheets scoured landscapes well beyond glacial troughs and nuclide inventories reveal a patchy legacy of erosional effectiveness that diminishes at high elevations such that 89 n 55 of bedrock samples retain inheritance above 1600 m we exploit this widespread nuclide inheritance in a markov chain monte carlo based inversion model to estimate long term erosion rates and surface exposure histories from 113 paired 10be 26al bedrock samples nuclide inventories with or without inheritance convey equally important information about the erosional effectiveness of the last ice sheet we define cosmogenic nuclide memory as the residence time of bedrock samples inside the nuclide production window 2 m depth where 80 of the total nuclide production occurs the cosmogenic nuclide memory is set by mean erosion rate and varies from 10 ka for samples eroded 2 m during the last glaciation to 1 ma for the slowest erosion rates we find that mean erosion rates are well constrained compared to the ratio of exposure to burial the inclusion of bedrock erosion in our computations thwarts the capacity to constrain surface exposure history or identify former nunataks from paired 10be 26al data ice carved surfaces reflect diverse erosion histories that are not straightforward to interpret from surficial morphology alone relative to the 10 mm kyr benchmark for polar ice masses we report point based mean erosion rates that vary by more than three orders of magnitude with glacial troughs and areal scour terrain eroding at 1 to 100 mm kyr blockfields at 0 8 16 mm kyr and tors at 0 8 7 7 mm kyr 5th 95th percentiles

frozen bed fennoscandian and laurentide ice sheets during the last glacial maximum the areal extents of the laurentide and fennoscandian ice sheets during the last glacial maximum about 20 000 years ago are well known1 but thickness estimates range widely from high domed2 to thin3 with large implications for our reconstruction of the climate system regarding for example northern hemisphere atmospheric circulation and global sea levels this uncertainty stems from difficulties in determining the basal temperatures of the ice sheets and the shear strength of subglacial materials4 a knowledge of which would better constrain reconstructions of ice sheet thickness here we show that in the absence of direct data the occurrence of ribbed moraines in modern landscapes can be used to determine the former spatial distribution of frozen and thawed bed conditions we argue that ribbed moraines were formed by brittle fracture of subglacial sediments induced by the excessive stress at the boundary between frozen and thawed bed conditions resulting from the across boundary difference in basal ice velocity maps of glacial landforms from aerial photographs of canada and scandinavia reveal a concentration of ribbed moraines around the ice sheet retreat centres of quebec keewatin newfoundland and west central fennoscandia together with the evidence from relict landscapes that mark glacial areas with frozen bed conditions the distribution of ribbed moraines on both continents suggest that a large area of the laurentide and fennoscandian ice sheets was frozen based and therefore high domed and stable during the last glacial maximum

zooming in on frozen bed patches scale dependent controls on fennoscandian ice sheet basal thermal zonation in this paper we explore geomorphological evidence allowing a first order reconstruction of the extent and pattern of frozen bed conditions under the last fennoscandian ice sheet we mapped relict landscapes i e glacial landforms and subaerially developed ground surfaces predating the last ice sheet and marking sustained frozen bed conditions at four different spatial scales at the ice sheet scale relict landscapes are most abundant between the last glacial maximum ice divide and the elevation axis of the scandinavian mountain range the location of frozen bed zones was mainly a function of dispersal centre location low surface temperatures and small strain heating and small ice thickness over the eastern flank of the mountain range at the mesoscale 260 360 km map area the pattern of relict surfaces is governed by inward cutting ice stream erosion topographical control was weak but relation to flow pattern was strong with the major frozen bed zone located where ice flow was strongly divergent at the regional scale 40 65 km map area in hilly terrain topographical control was strong with relict surfaces only appearing above a plane dipping in the up ice direction at the local scale 12 14 km map area control by topography was likewise strong but the detailed boundary pattern was irregular with specific landforms occurring both up and down ice of frozen patches

deglaciation of fennoscandia abstract to provide a new reconstruction of the deglaciation of the fennoscandian ice sheet in the form of calendar year time slices which are particularly useful for ice sheet modelling we have compiled and synthesized published geomorphological data for eskers ice marginal formations lineations marginal meltwater channels striae ice dammed lakes and geochronological data from radiocarbon varve optically stimulated luminescence and cosmogenic nuclide dating this is summarized as a deglaciation map of the fennoscandian ice sheet with isochrons marking every 1000 years between 22 and 13 cal kyr bp and every hundred years between 11 6 and final ice decay after 9 7 cal kyr bp deglaciation patterns vary across the fennoscandian ice sheet domain reflecting differences in climatic and geomorphic settings as well as ice sheet basal thermal conditions and terrestrial versus marine margins for example the ice sheet margin in the high precipitation coastal setting of the western sector responded sensitively to climatic variations leaving a detailed record of prominent moraines and other ice marginal deposits in many fjords and coastal valleys retreat rates across the southern sector differed between slow retreat of the terrestrial margin in western and southern sweden and rapid retreat of the calving ice margin in the baltic basin our reconstruction is consistent with much of the published research however the synthesis of a large amount of existing and new data support refined reconstructions in some areas for example the lgm extent of the ice sheet in northwestern russia was located far east and it occurred at a later time than the rest of the ice sheet at around 17 15 cal kyr bp we also propose a slightly different chronology of moraine formation over southern sweden based on improved correlations of moraine segments using new lidar data and tying the timing of moraine formation to greenland ice core cold stages retreat rates vary by as much as an order of magnitude in different sectors of the ice sheet with the lowest rates on the high elevation and maritime norwegian margin retreat rates compared to the climatic information provided by the greenland ice core record show a general correspondence between retreat rate and climatic forcing although a close match between retreat rate and climate is unlikely because of other controls such as topography and marine versus terrestrial margins overall the time slice reconstructions of fennoscandian ice sheet deglaciation from 22 to 9 7 cal kyr bp provide an important dataset for understanding the contexts that underpin spatial and temporal patterns in retreat of the fennoscandian ice sheet and are an important resource for testing and refining ice sheet models

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

scaling factors for the rates of production of cosmogenic nuclides for geometric shielding and attenuation at depth on sloped surfaces abstract the decrease in rates of production of cosmogenic nuclides occurs because of shielding of cosmic rays by mountains sloped surfaces and local rock formations that block them when a large part of the sky is blocked this correction is large and requires detailed model calculations this paper considers three geometries a rectangular obstruction a triangular obstruction and a sloped surface other geometries can be considered as a combination of these the results are presented in terms of formulas and graphs so that the reader can easily apply them to common field situations any use of cosmogenic nuclides in the study of geomorphic processes or forms must consider factors that introduce variations in the production of nuclides

ice cap erosion patterns from bedrock 10be and 26al southeastern tibetan plateau quantifying glacial erosion contributes to our understanding of landscape evolution and topographic relief production in high altitude and high latitude areas combining in situ be 10 and al 26 ana

topographical evolution and glaciation history of south greenland constrained by paired 26al 10be nuclides abstract the pattern of cosmogenic nuclide inheritance within bedrock surfaces in previously glaciated regions can be used to assess the efficiency of glacial erosion and constrain topographic evolution here we present fifty new in situ cosmogenic 10be and 26al pairs in bedrock and boulder erratics from south greenland the data demonstrate rapid retreat of the south greenland ice sheet in the early holocene and a clear gradient in cosmogenic nuclide inheritance in bedrock with elevation sites 800 m above sea level m a s l generally show limited or no nuclide inheritance exposure from before the last glaciation in contrast the nuclide inheritance in samples from sites at higher elevations varies from negligible to 90 kyr of exposure before the last glaciation depending on the topographic setting our results suggest that steering of ice into troughs led to substantial erosion 2 6 m in the troughs over the last glacial cycle even at elevations above 1500 m a s l while bedrock on summit flats at similar elevations experienced much less erosion inverse markov chain monte carlo mcmc modelling of the nuclide inventories further indicates that selective linear erosion developed 1 myr ago at the summit flat closest to the present ice margin and effectively limited the subsequent erosion to 2 6 m erosion of the redekammen ridge some 40 km from the present ice margin was slightly more efficient over the last 1 myr indicating that selective linear erosion is less pronounced or developed later here than at the summit flats long term ice cover histories are generally less well constrained than the erosion histories the results suggest that the summit flats were possibly ice covered during large parts of the last 1 myr and experienced minimal erosion during this interval but it is also possible that they were only covered by ice during the coldest parts of the glacial periods and that a cover of regolith or overlying rock was stripped off during one of the latest major glaciations although inverse modelling cannot distinguish between these scenarios we identify the more likely ice cover scenarios for each site based on the geological setting and surface characteristics

clay mineralogy chemical weathering and landscape evolution in arctic alpine sweden abstract the purpose of this research was to 1 characterize the clay mineralogy of soils in and adjacent to karkevagge a recently deglaciated valley in arctic sweden 2 document chemical weathering in a periglacial environment and 3 use the mineralogy to help explain landscape evolution soil samples were analyzed from 11 sites that differ in elevation parent material drainage slope and vegetation parent materials include residuum alluvium colluvium and glaciofluvial material derived from garnet mica schist plus in one locality a till of granitic origin x ray diffraction xrd was used to characterize the clay size fraction

the goldilocks dilemma big ice little ice or just right ice in the eastern canadian arctic our conceptions of the ne sector of the laurentide ice sheet lis at the last glacial maximum lgm have evolved through three major paradigms over the past 50 years until the late 1960s the conventional view was that the eastern canadian arctic preserved only a simple deglacial sequence from a lis margin everywhere at the continental shelf edge flint paradigm glacial geologic field studies began in earnest in this region in the early 1960s and within the first decade field evidence documenting undisturbed deposits predating the lgm led a pendulum swing to a consensus view that large coastal stretches of the eastern canadian arctic remained free of actively eroding glacial ice at the lgm and that the most extensive ice margins occurred early in the last glacial cycle this minimalist paradigm dominated until the late1980s when an expanded data set from shallow marine studies indicated lgm ice at least locally reached the continental shelf within the past decade the marine data coupled with new evidence from lake sediments and cosmogenic exposure dates on moraines and glaciated terrain in the eastern canadian arctic has led to a new paradigm that better reconciles the terrestrial and marine evidence collectively these lines of evidence indicate that all of southern baffin island was glaciated at the lgm but that some coastal uplands north of cumberland sound remained above the limit of actively eroding glacial ice even though outlet glaciers reached the continental shelf in front of most fiords and sounds the most plausible explanation for the observed glacial limits is that low gradient relatively fast moving outlet glaciers sliding on deformable sediments occupied marine embayments and fiords contrasting with slower moving ice frozen to its bed on the intervening crystalline terrain slow moving ice frozen to its bed would have had steeper surface gradients hence would have terminated inland from the coast this scenario is consistent with observations indicating high elevation coastal terrain remained unglaciated even though outlet glaciers reached the continental shelf lgm summer temperatures were apparently much lower than present as lakes in the ice free regions were permanently frozen

provenance of icebergs during heinrich event 3 and the contrast to their sources during other heinrich episodes the sources of ice rafted debris ird from heinrich layer 3 h 3 in the north atlantic were studied by means of pb isotopic analyses of single and multiple grain samples of ice rafted feldspars from core v28 82 49 27 n 22 16 w pb ratios of h 3 grains point to multiple continental sources and are similar to the isotopic composition of the background sediment this similarity as well as previous observations about the age and the sr and nd isotopic composition of the fine fraction of h 3 in cores of the same area are all consistent with the hypothesis that in the eastern north atlantic along the latitude band of maximum ird deposition 40 50 n h 3 is a product of foraminifera dissolution and or low productivity in contrast analyses of composite samples of h 1 h 2 h 4 and h 5 plot in 206pb 204pb versus 206pb 204pb coordinates along the churchill province line supporting the premise that the hudson strait was the major pathway of iceberg drainage during these four events since an advance of the laurentide ice sheet during h 3 is demonstrated by increases in detrital carbonate at the level of h 3 in cores from the western north atlantic the results obtained here suggest that if indeed that advance took place the iceberg discharge melted mostly in the western basin

mid pleistocene cosmogenic minimum age limits for pre wisconsinan glacial surfaces in southwestern minnesota and southern baffin island a multiple nuclide approach abstract paired 10 be and 26 al analyses n 14 indicate that pre wisconsinan glaciated bedrock surfaces near the northern baffin island and southern minnesota paleo margins of the laurentide ice sheet have long and complex histories of cosmic ray exposure including significant periods of partial or complete shielding from cosmic rays using the ratio 26 al 10 be we calculate that striated outcrops of sioux quartzite in southwestern minnesota southern margin were last overrun by ice at least 500 000 years ago weathered bedrock tors on the once glaciated uplands of baffin island northern margin are eroding no faster than 1 1 m myr 1 the equivalent of at least 450 000 years of surface and near surface exposure our data demonstrate that exposure ages and erosion rates calculated from single nuclides can underestimate surface stability dramatically because any intermittent burial and the resultant lowering of nuclide production rates and nuclide abundances will remain undetected

palaeoglaciology of an ice sheet through a glacial cycle the european ice sheet through the weichselian abstract satellite images provide unique means of identifying large scale flow generated lineations produced by former ice sheets they can be interpreted to reconstruct the major elements which make up the integrated large scale structure of ice sheets ice divides ice streams interstream ridges ice shelves calving bays the evolving palaeoglaciological structure of the european ice sheet during its decay from the last glacial maximum lgm is reconstructed by reference to these components and in the context of a new map showing isochrons of retreat during the retreat phase in particular the time dependent dynamic evolution of the ice sheet and the pattern of ice stream development are reconstructed crossing lineations are widespread the older ones are suggested to have formed during molten bed phases of ice sheet growth and preserved by frozen bed conditions during the glacial maximum particularly in areas which lay during deglaciation beneath ice divides and inter ice stream ridges both areas of slow flow and possibly frozen bed conditions four phases of growth a1 to a4 and five phases of decay r1 to r5 are used to describe the major climatically and dynamically determined stages in the evolution of the ice sheet through the last glacial cycle the growth and decay patterns are quite different and associated with major shifts in the ice divide reflecting growth from the fennoscandian mountains and decay away from marine influenced margins these patterns were determined by the locations of nucleation areas spatial patterns of climate and calving at marine margins the prevalence of streaming within the retreating ice sheet suggests that the mean elevation of the ice sheet was lower than predicted from glaciological models which do not include streaming and that this might reconcile glaciological models and earth rheology models which infer paleao ice sheet thickness by inverting sea level data

calculating quaternary glacial erosion rates in northeast scotland northeast scotland is an area exhibiting selective erosion by quatemary ice sheets in this area both glacial and preglacial landforms exist in close proximity the depths of erosion which this modification represents are calculated on the assumption of various depths of preglacial weathering a depth of erosion of between 34 and 62 m per unit area is indicated calculated rates of erosion are 0 021 nun a for the entire 2 3 m y of the quaternary and between 0 1 and 0 5 mm aa1 on the assumption that glacial conditions existed in this area for 500 000 years and 100 000 years respectively these figures are compared to the offshore sedimentary record in the adjacent west central north sea the volume of sediment deposited offshore is equivalent to a depth of erosion of 195 m per unit area yielding an average erosion rate of 0 085 mm a i over the entire quatemary rates of erosion were low in the preglacial pliocene 0 049 mm a 1 and early quatemary 0 063 mm a the expansion of ice sheets across the area in the middle quatematy was associated with a sharp increase in the rates of erosion 0 13 mm a but the last late devensian ice sheet in the area was less erosive 0 095 mm a the estimated rates of erosion represented by the offshore sedimentary record therefore exceed the estimated rates of glacial erosion from the onsho re geomorphological reconstruction

preglacial surface remnants and quaternary glacial regimes in northwestern sweden abstract we present a detailed map of the distribution of preglacial surface remnants in the kebnekaise region of northwestern sweden in this mountain area we discern four important large scale geomorphological units each representing a specific set of erosional agents and formative conditions these are i intact preglacial surface remnants characterized by gentle slopes round summits wide shallow valleys and an absence of rock basins ii preglacial surface remnants showing signs of minor glacial erosion and deposition iii glacially scoured surfaces including glacial troughs iv deep fluvial valleys cut into the preglacial surface the pattern of glacial erosion is explained as the result of three specific modes of glaciation known to have existed during the last 120 000 years and inferred to have repeatedly prevailed during the last 2 75 million years cirque glaciation mountain ice sheets and fennoscandian ice sheets a deep ocean oxygen isotope record of foraminifera from the north atlantic dsdp 607 was used to infer the temporal extent of these modes of glaciation during the last 2 75 million years we interpret the preglacial landscape preservation and the pattern of glacial erosion in terms of the configuration the basal thermal regime and the duration of such glaciation events the average subglacial thermal regime of both ice sheet types was frozen on the uplands and melting in the main valleys where outlet glaciers and ice streams formed the pre glacial landscape is best preserved at intermediate elevations low enough not to have been covered by cirque glaciers and apparently high enough not to have experienced melted bed conditions and subglacial erosion during ice sheet overriding events in a narrow high relief zone along the elevation axis interglacial fluvial erosion was morphologically important the absence of glacial erosion on uplands in this zone allowed fluvial erosion to commence on the same locations during each ice free interval in contrast no persistent fluvial valley pattern could develop in zones subjected to repeated glacial scouring and hence derangement of fluvial patterns

fennoscandian palaeoglaciology reconstructed using a glacial geological inversion model the evolution of ice sheet configuration and flow pattern in fennoscandia through the last glacial cycle was reconstructed using a glacial geological inversion model i e a theoretical model that formalises the procedure of using the landform record to reconstruct ice sheets the model uses mapped flow traces and deglacial melt water landforms as well as relative chronologies derived from cross cutting striae and till lineations as input data flow trace systems were classified into four types i time transgressive wet bed deglacial fans ii time transgressive frozen bed deglacial fans iii surge fans and iv synchronous non deglacial event fans using relative chronologies and aggregation of fans into glaciologically plausible patterns a series of ice sheet configurations at different time slices was erected a chronology was constructed through correlation with dated stratigraphical records and proxy data reflecting global ice volume geological evidence exists for several discrete ice sheet configurations centred over the scandinavian mountain range during the early weichselian the build up of the main weichselian fennoscandian ice sheet started at approximately 70 ka and our results indicate that it was characterised by an ice sheet with a centre of mass located over southern norway this configuration had a flow pattern which is poorly reproduced by current numerical models of the fennoscandian ice sheet at the last glacial maximum the main ice divide was located overthe gulf of bothnia a major bend in the ice divide was caused by outflow of ice to the northwest over the lowest part of the scandinavian mountain chain widespread areas of preserved pre late weichselian landscapes indicate that the ice sheet had a frozen bed core area which was only partly diminished in size by inward transgressive wet bed zones during the decay phase

a relict landscape in the centre of fennoscandian glaciation cosmogenic radionuclide evidence of tors preserved through multiple glacial cycles the presence of well developed tors boulder fields and weathering mantles in the parkajoki area of northeastern sweden near the centre of fennoscandian glaciation has been used to suggest that these landscapes were preserved during all glacial cycles since ice sheet initiation in the late cainozoic this implies that all successive large scale glaciations must have had frozen bed conditions across this area to allow for subglacial landscape preservation cosmogenic 10be and 26al data from three tors and a meltwater channel in the parkajoki area were used to test this hypothesis of landscape preservation through multiple glacial cycles apparent exposure ages of tor summit bedrock surfaces ranging between 79 and 37 ka in an area deglaciated at 11 ka are consistent with the interpretation of these features as relict landforms that have survived glaciation with little or no erosion single nuclide minimum exposure age data require that the tors have survived at least two complete glacial cycles this estimate is based on i the approximate duration of periods of ice sheet cover versus ice free conditions as deduced from the dsdp 607 marine benthic foraminifer oxygen isotope record in conjunction with ii a record of fennoscandian ice sheet flow traces and hence ice sheet extent and iii noting that cosmogenic nuclides are accumulated only during ice free periods in addition mean cosmogenic 26al 10be concentration ratios from two of the sites indicate a minimum model total history of 605 ka and a maximum erosion rate of 1 6 m ma 1 thus the numerical ages confirm the overall qualitative interpretation of landscape preservation through multiple glacial cycles

preservation of landforms under ice sheets and ice caps abstract this article addresses the question of whether or not distinct glacial and non glacial landforms can survive beneath ice sheets and ice caps with little or no morphological alteration a review of recent work documents the existence of pre last stadial landforms and landscapes in areas covered by the fennoscandian and laurentide ice sheets a substantial number of independent works indicate that landforms such as eskers drainage channels and boulder fields have escaped destruction despite complete ice overriding during several tens of millenia full preservation of former ground surfaces or delicate landforms probably is linked to areas where the ice sheet base was continuously frozen to its bed larger robust landforms such as large drumlins appear to have been preserved even under wet based conditions in glaciated areas patches preserved under dry cold based conditions provide important windows towards the past showing landscapes that were destroyed in surrounding areas affected by wet based and eroding ice some consequences for the research fields of non glacial geomorphology archaeology and botany include the possibility of subglacial museums and refugia a time space model describes geomorphological access to information from older events in glaciated areas

exposure ages from mountain dipsticks in mac robertson land east antarctica indicate little change in ice sheet thickness since the last glacial maximum past changes in east antarctic ice sheet eais volume are poorly known and diffi cult to measure yet are critical for predicting the response of the ice sheet to modern climate change in particular it is important to identify the sources of sea level rise since the last glacial maximum lgm and ascertain the present day stability of the world s largest ice sheet we present altitudinal transects of 10 be and 26 al exposure ages across the framnes mountains in mac robertson land that allow the magnitude and timing of eais retreat to be quantifi ed our data show that the coastal eais thinned by at most 350 m in this region during the past 13 k y this reduction in ice sheet volume occurred over a 5 k y period and the present icesheet profi le was attained ca 7 ka in contrast to the west antarctic ice sheet which continues to retreat today combined with regional offshore and terrestrial geologic evidence our data suggest that the reduction in eais volume since the lgm was smaller than that indicated by contemporary ice sheet models and added little meltwater to the global oceans stability of the ice margin since the middle holocene provides support for the hypothesis that eais volume changes are controlled by growth and decay of northern hemisphere ice sheets and associated global sea level changes

reconstructing the erosion history of glaciated passive margins applications of in situ produced cosmogenic nuclide techniques offshore sediment accumulations provide an intriguing record of the net sediment output resulting from geomorphological evolution of the circum atlantic continental margin since the commencement of neogene glaciation however the onshore record of the timing pattern and amount of bedrock erosion that produced these sediments is comparatively poorly constrained and understood although there are good general models of glaciation history the geomorphology of circum atlantic continental margin mountains as assessed from remote sensing data and field observations includes palimpsest landforms and landscapes that reflect a complex pattern of spatial and temporal variations in the impact of glacial fluvial and periglacial processes perhaps most surprising is that despite having been repeatedly overridden by large ice sheets parts of the landscape appear to be relict with nonglacial morphology this has important implications both for glaciological conditions under ice sheets and for sediment source areas and erosion rates conventional dating and analysis have provided an excellent way to begin unravelling the timing and pattern of erosion landform development and possible landform preservation under ice however testing hypotheses developed from current models and addressing critical unresolved questions requires additional approaches the use of in situ cosmogenic nuclide production in bedrock is a new approach for investigating landscape evolution in mountainous areas with careful interpretation of geomorphological settings cosmogenic nuclides can be used to determine apparent surface exposure age and landscape preservation and constrain erosion depths and duration of burial by ice here we provide a framework for the interpretation of cosmogenic nuclide concentrations in bedrock surfaces of landscapes affected by glacial fluvial and periglacial processes illustrated with examples from the northern swedish mountains this demonstrates potential uses of cosmogenic nuclide techniques and provides a foundation for attempts to improve geomorphologically based reconstructions of relict landscapes to reconstruct and analyse the dynamics of landscape change in glacial times and to define the consequences of different process regimes in terms of erosion patterns sediment transport and the supply of sediments that are deposited offshore

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

cosmogenic radionuclides from fiord landscapes support differential erosion by overriding ice sheets the interpretation of differentially weathered mountainous areas along the fringes of pleistocene ice sheets is fundamental for determining ice sheet behavior and thickness during the last glaciation two existing interpretations are either that highly weathered uplands remained as nunataks while freshly eroded troughs held outlet glaciers during the last glaciation or that uplands and lowlands were equally covered by ice but that it was differentially erosive as a function of its spatially variable basal thermal regime cosmogenic radionuclide measurements from 33 bedrock samples and 27 upland erratics from differentially weathered fi ord landscapes on northeastern baffi n island shed light on laurentide ice sheet lis dynamics and thickness tors on weathered upland surfaces have minimum 10 be ages between ca 50 and ca 170 ka n 12 whereas the majority of erratics perched in the uplands range from ca 10 to ca 13 ka n 14 indicating that the whole landscape was glaciated during the last glacial maximum lgm glacially sculpted bedrock n 7 near sea level refl ects the age of deglaciation and increasing amounts of isotopic inheritance in highelevation sculpted bedrock n 3 higher elevation intermediately weathered bedrock n 11 and highest elevation intensely weathered bedrock refl ect the weakening of erosive power as the ice sheet transitioned from fi ords to interfi ord plateaus cold based glaciation of uplands was contemporaneous with warm based glaciation in fi ords suggesting the presence of ice streams 26 al and 10 be concentrations measured in 10 bedrock samples indicate that tors have experienced a complex history of alternating periods of exposure burial and limited glacial erosion the paired isotope data reveal a minimum duration of burial of 80 500 k y presumably by cold based ice and indicate that the tors have an age of at least 150 580 ka these data together with other reconstructions of ice streams in the eastern canadian arctic suggest that ice streams were a large infl uence on northeastern lis dynamics throughout the late quaternary thus the northeastern lis was sensitively tied with north atlantic thermohaline circulation and abrupt climate change

limited modification of mid latitude landscapes by ice sheets the case of northeast scotland the paper uses a case study in scotland to examine the amount and processes of landscape modification by quaternary ice sheets there is an inverse correlation between the distribution of landforms of glacial erosion and pre glacial landscape remnants in northeast scotland the implication is that in places ice sheets can preserve a pre glacial landscape unscathed while elsewhere they remove the pre glacial weathered rock the location of glacial protection or erosion is strongly influenced by the topography and its influence on former ice sheet flow and basal thermal regime the classic glacially eroded landscape of areal scouring can be produced by the removal of only 10 50 m of weathered rock furthermore rock basins often regarded as the hallmark of glacial erosion may be directly inherited from the pre glacial pattern of deep weathering

landscape preservation under fennoscandian ice sheets determined from in situ produced 10be and 26al some areas within ice sheet boundaries retain pre existing landforms and thus either remained as ice free islands nunataks during glaciation or were preserved under ice differentiating between these alternatives has significant implications for paleoenvironment ice sheet surface elevation and ice volume reconstructions in the northern swedish mountains in situ cosmogenic 10be and 26al concentrations from glacial erratics on relict surfaces as well as glacially eroded bedrock adjacent to these surfaces provide consistent last deglaciation exposure ages 8 13 kyr confirming ice sheet overriding as opposed to ice free conditions however these ages contrast with exposure ages of 34 61 kyr on bedrock surfaces in these same relict areas demonstrating that relict areas were preserved with little erosion through multiple glacial cycles based on the difference in radioactive decay between 26al and 10be the measured nuclide concentration in one of these bedrock surfaces suggests that it remained largely unmodified for a minimum period of 845 418 461 kyr these results indicate that relict areas need to be accounted for as frozen bed patches in basal boundary conditions for ice sheet models and in landscape development models subglacial preservation also implies that source areas for glacial sediments in ocean cores are considerably smaller than the total area covered by ice sheets these relict areas also have significance as potential long term subglacial biologic refugia

glacial geomorphology and geographic information systems recent developments in the field of glacial geomorphology have dramatically increased the need to acquire maintain manipulate and analyze large amounts of landform landscape and sediment data the use of geographic information systems gis has provided new platforms and tools for analysis and visualization of geomorphic data glacial geomorphologists have used gis to integrate multi source data manage multi scale studies identify previously unrecognized spatial and temporal relationships and patterns in geomorphic data and to link landform data with numerical models as part of model calibration and verification gis based analyses associated with numerical modeling are improving our understanding of glacial landscape evolution and are allowing new quantitative and systematic examinations of spatial and temporal patterns of glacial landforms and processes this has allowed for the development of insights and concepts that would be unlikely to arise using traditional methods alone key recommendations for future research and applications in glacial geomorphology include enhanced gis education and dissemination the development of standards and conventions for glacial geomorphic data community projects to collect data into readily accessible databases and enhanced use of linked gis model frameworks to address major issues in glacial geomorphology

glaciation of scotland during the younger dryas stadial a review considerable research effort in recent years has refined our knowledge of the landforms and sedimentary sequences generated by glaciers of the last cold episode in scotland the younger dryas and the chronology of their formation these recent advances have benefited from new technologies such as high resolution digital terrain models numerical ice sheet simulations and cosmic ray surface exposure dating this review presents a summary of recent younger dryas research in scotland particularly focusing on studies from the last two decades the findings of these investigations are compared with those of earlier workers and critically are appraised in terms of their relevance to five key aspects of younger dryas glaciation growth of the ice cap its geometry dynamics mode of decay and likely stadial climate minor differences aside the consensus view appears to favour a relatively thick but areally restricted central ice cap surrounded by satellite ice fields at its centre the ice cap was probably thickest during the first 500 years of the stadial after which it most likely thinned as the climate became increasingly arid outlet glaciers were dynamic only in marginal areas where they produced abundant moraine sequences during deglaciation but throughout much of the stadial central areas of the ice cap effected only minimal landscape modification deglaciation took place by active retreat under a rapidly warming climate overall the stadial was dominated by much colder and drier conditions than present and probably experi enced greater intra annual temperature ranges copyright 2009 john wiley sons ltd