late surge glacial conditions on bakaninbreen svalbard and implications for surge termination 1 bakaninbreen is a polythermal glacier in southern spitsbergen svalbard that last surged between 1985 and 1995 seismic reflection data were acquired during early quiescence in spring 1998 just upstream of the surge front the results were combined with complementary ground penetrating radar data to investigate the glacial structure and basal conditions we find no difference between the ice thickness values determined from the seismic and radar methods suggesting that any layer of basal ice cannot be greater than 5 m thick interpretation of the amplitude of the seismic reflections indicates the presence of permafrost close to the glacier base a thin layer of thawed deforming sediment separates the glacier from this underlying permafrost in an area just upstream of the surge front the permafrost becomes discontinuous and may even be absent the ice being underlain by 10 15 m of thawed sediments overlying deeper bedrock high pressure water is believed to have been required to maintain the propagation of the surge and this area of thawed sediment is interpreted as a route for that water to escape from the basal system when the surge front passed over this thawed bed the escaping water reduced the pressure in the subglacial hydraulic system initiating the termination of the surge surge termination was therefore primarily controlled by the presurge permafrost distribution beneath the glacier rather than any feature of the surge itself this termination mechanism is probably limited to surges in polythermal glaciers but the techniques used may have wider glaciological applications

soil endemism and its relation to soil formation theory abstract in this paper the concept of soil endemism is elucidated endemic soils are restricted to a particular geographic area based on a unique combination of soil forming factors that may operate from the landscape to the eco region scale to validate that soils are endemic soil bodies occurring on different continents but having a similar combination of soil forming factors were compared using national soil survey characterization data a key finding is that similar soil families occur within a given climate class koppen trewartha system and vegetation type bailey s eco region division reinforcing the former concept of zonal soils in a second test soil series were compared within a soil family from randomly selected benchmark soil series using the state soil geographic statsgo database and evaluated in terms of the soil forming factors contributing to endemism this analysis showed that soil endemism is locally influenced by parent material e g volcanic ash clay secondary silica and topography e g closed basins i e intrazonal soils soils lacking a well developed profile because of youth of parent material or peculiar conditions of parent material or relief azonal soils do not show endemism therefore zonal and intrazonal soils generally are endemic and azonal soils tend to be non endemic the concept of endemism is important for detecting rare unique or endangered soils

surface water temperature salinity and density changes in the northeast atlantic during the last 45 000 years heinrich events deep water formation and climatic rebounds we developed a new method to calculate sea surface salinities sss and densities ssd from planktonic foraminiferal 18o and sea surface temperatures sst as determined from planktonic foraminiferal species abundances sst sss and ssd records were calculated for the last 45 000 years for biogeochemical oceanic flux study bofs cores 5k and 8k recovered from the northeast atlantic the strongest feature is the dramatic drop in all three parameters during the heinrich ice rafting events we modelled the possibility of deepwater formation in die northeast atlantic from the ssd records by assuming that the surface waters at our sites cooled as they flowed further north comparison with modelled north atlantic deepwater densities indicates that there could have been periods of deepwater formation between 45 000 and 30 000 14c years b p interrupted by iceberg meltwater input of heinrich event 3 and 4 at 27 000 and 38 000 14c years b p and during the holocene no amount of cooling in the northeast atlantic between 30 000 and 13 000 years could cause deep water to form because of the low salinities resulting from the high meltwater inputs from icebergs our records indicate that after each heinrich event there were periods of climatic rebound with milder conditions persisting for up to 2000 years as indicated by the presence of warmer and more saline water masses after these warm periods conditions returned to average glacial levels these short term cold and warm episodes in the northeast atlantic are superimposed on the general trend towards colder conditions of the last glacial maximum lgm heinrich event 1 appears to be unique as it occurs as insolation rose and was coeval with the initial melting of the fennoscandian ice sheet we propose that meltwater input of heinrich event 1 significantly reduced north atlantic deep water formation reducing the heat exchange between the low and high latitudes thus delaying deglaciation by about 1500 radiocarbon years 2000 calendar years

ice caps existed throughout the lateglacial interstadial in northern scotland we constrain in detail fluctuations of two former ice caps in nw scotland with multibeam seabed surveys geomorphological mapping and cosmogenic 10 be isotope analyses we map a continuous sequence of 40 recessional moraines stretching from 10 km offshore to the wester ross mountains surface exposure ages from boulders on moraine ridges in assynt and the summer isles region show that substantial dynamic ice caps existed in nw scotland between 13 and 14 ka bp we interpret this as strong evidence that large active glaciers probably survived throughout the lateglacial interstadial and that during the older dryas period ca 14 ka bp ice caps in nw scotland were thicker and considerably more extensive than in the subsequent younger dryas stadial by inference we suggest that lateglacial ice cap oscillations in scotland reflect the complex interplay between changing temperature and precipitation regimes during this climatically unstable period ca 15 11 ka bp natural environment research council nerc copyright 2008 reproduced with the permission of nerc published by john wiley sons ltd

was the younger dryas triggered by a flood draining of a huge lake into the northern atlantic may have triggered a cold period 12 900 years ago the route taken by the flood waters remains unknown

abrupt increase in greenland snow accumulation at the end of the younger dryas event the warming at the end of the last glaciation was characterized by a series of abrupt returns to glacial climate the best known of which is the younger dryas event1 despite much study of the causes of this event and the mechanisms by which it ended many questions remain unresolved1 oxygen isotope data from greenland ice cores2 4 suggest that the younger dryas ended abruptly over a period of about 50 years dust concentrations2 4 in these cores show an even more rapid transition 20 years this extremely short timescale places severe constraints on the mechanisms underlying the transition but dust concentrations can reflect subtle changes in atmospheric circulation which need not be associated with a large change in climate here we present results from a new greenland ice core gisp2 showing that snow accumulation doubled rapidly from the younger dryas event to the subsequent preboreal interval possibly in one to three years we also find that the accumulation rate change from the oldest dryas to the bo11ing allerod warm period was large and abrupt the extreme rapidity of these changes in a variable that directly represents regional climate implies that the events at the end of the last glaciation may have been responses to some kind of threshold or trigger in the north atlantic climate system

chironomid inferred late glacial air temperatures at whitrig bog southeast scotland this paper presents the first chironomid inferred mean july air temperature reconstruction for the late glacial in britain the reconstruction suggests that the thermal maximum occurred early in the interstadial with temperatures reaching about 12 degreesc there was then a gradual downward trend to about 11 degreesc punctuated by four distinct cold oscillations of varying intensity at the beginning of the younger dryas mean july temperatures fell to about 7 5 degreesc but gradually increased to about 9 degreesc before a rapid rise at the onset of the holocene the chironomid inferred temperature curve agrees closely both in general trends and in detail with the grip ice core oxygen isotope curve the reconstructed temperatures are 2 4 degreesc lower than coleopteran inferred temperatures but are closer to those inferred from plant macrofossils and glacial equilibrium line altitudes during the younger dryas copyright c 2000 john wiley sons ltd

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

glacial lake agassiz its northwest maximum extent and outlet in saskatchewan emerson phase abstract six different lines of evidence support the hypothesis that glacial lake agassiz expanded an additional 70 000 km2 over that previously mapped in northwestern saskatchewan and that the lake discharged out the northwestern clearwater outlet then through glacial lake mcconnell and mackenzie river to the arctic ocean elevations of formerly unmapped 1 strandlines and 2 glaciolacustrine sediments between the previously mapped northwest limit of lake agassiz and the clearwater lower athabasca spillway indicate that water extended 170 km farther northwest recently mapped strandlines at elevations up to 60 m above the previously mapped extent of lake agassiz can be traced along 3 isobases to the mouth of the spillway based upon 4 six radiocarbon dates recovered from spillway flood deposits in the athabasca river valley and its late pleistocene delta the 5 clearwater spillway was cut at 9 9 ka bp this date is synchronous with the initiation of the emerson phase 9 9 ka bp in the southern lake agassiz basin and 6 coincides with the position of the laurentide ice sheet at the cree lake moraine 10 ka bp along the northern margin of the lake following closure of the eastern outlets at the onset of the emerson phase lake agassiz transgressed toward the northwest into the deglaciated and isostatically depressed glacial foreland in the churchill river valley to an elevation of 490 m the pre flood elevation of the churchill mackenzie drainage divide at the head of the clearwater lower athabasca spillway the beaver river moraine an earthen drainage divide was breached resulting in lowering lake agassiz 52 m to a stable elevation at 438 m the lake discharged 21 000 km3 of water into the arctic ocean that raised global sea level by 6 cm

soil landscape interplays at harmony point nelson island maritime antarctica chemistry mineralogy and classification abstract soils and landforms of nelson island remain one of the least studied in the south shetlands archipelago despite that it is one of the oldest ice free areas and is strongly vegetated in this paper we examine the main processes and factors of soil formation at harmony point and the relation of soils to landforms vegetation and lithology to achieve the goals 26 pedons were collected and studied from a 4 km2 ice free area at harmony point s62 18 w059 10 on the southern area of nelson island maritime antarctica the soils were sampled on all representative local landforms including three levels of uplifted marine terraces up to cryoplanated plateau waterlogged depressions rock felsenmeer debris slopes and patterned ground and a paraglacial border of the ice cap 270 m a s l sampling along the cryoplanated plateau was carried out along a gradient extending inland from the margins of the ice cap and sampling of the marine terraces was performed along a chronosequence under varying bird nesting influence and age the main pedogenetic processes observed in this area are marked phosphatization melanization from the accumulation of organic matter and cryoturbation soil development varies from weakly developed shallow stony and cryoturbated to well developed and organic rich phosphate soils with colors ranging from grayish to brown the mineralogical composition of the clay fraction contains secondary minerals indicating the active role of chemical weathering ornithogenic soils have mature phosphate minerals such as vivianite and taranakite as well as poorly crystalline leucophosphite intensively cryoturbated soils are underlain by permafrost and are classified as typic haploturbels polygonal soils are widespread on the cryoplanated plateau areas without permafrost were classified as typic gelorthents phosphatization is a dominant soil forming process in this area and is associated with past and present day guano accumulation by bird nesting and has led to the the development of deeper ornithogenic haplorthels the ornithogenic soils occur at different topographic levels on the cryplanated platform and marine terraces high p concentrations can be used as a proxy of the past nesting birds activities with far reaching implications especially with regards to vegetation growth and microbial activity and diversity

the loch lomond readvance on the isle of mull scotland glacier reconstruction and palaeoclimatic implications geomorphological mapping of mull provides evidence for an icefield 143 km2 in area flanked by six corrie glaciers with a total area of ca 13 km2 the absence of lateglacial periglacial features shorelines and pollen sites from the area occupied by this readvance together with radiocarbon dating of shell fragments confirm that it occurred during the loch lomond younger dryas stade the thickness of glacigenic deposits within the area of the readvance is attributed to reworking of paraglacial sediments up valley continuity of recessional moraines indicates that the ice remained active and near to equilibrium during retreat consistent with slow warming following the coldest part of the stade reconstructed equilibrium line altitudes elas imply vigorous snow blowing by westerly winds and are consistent with a general southwestwards decline in elas across the scottish highlands an ela of 250 m was calculated for the mull icefield using an ablation accumulation balance ratio abr approach palaeotemperature and palaeoprecipitation estimates were derived by calculating a theoretical regional ela from meteorological data and assuming that the combination of temperature and precipitation implied by the theoretical ela approximates conditions at 250 m on mull during the loch lomond stade the result indicates a mean july sea level temperature of 5 7 0 5 c and a mean annual precipitation at 250 m of ca 2700 3800 mm best estimate 3200 mm indicating higher precipitation totals than at present owing to more vigorous atmospheric circulation copyright 2002 john wiley sons ltd

soil geomorphic classification soil taxonomy and effects on soil richness assessments the study of pedodiversity and soil richness depends on the notion of soils as discrete entities soil classifications are often criticized in this regard because they depend in part on arbitrary or subjective criteria in this study soils were categorized on the basis of the presence or absence of six lithological and morphological characteristics richness vs area relationships and the general pattern of soil variability and diversity were then compared to analyses of pedodiversity based on soil taxonomy the study area consists of sixteen 0 13 ha plots on forested sideslopes of the ouachita mountains arkansas with a minimum of 20 classified soil pits per plot an ad hoc classification was developed from the standpoint of soil geomorphology and studies of the coevolution of soils and landscapes and based on the regional environmental framework soils were classified based on 1 underlying geology shale sandstone bedrock or transported sandstone rock fragments and on the presence or absence of 2 texture contrast subsoils 3 eluvial horizons 4 surface and or subsurface stone lines or zones 5 lithological contrasts between soil and underlying geology and 6 redoximorphic features the soil geomorphic classification sgc yielded 40 different soil types out of 288 possible different combinations of the criteria compared to 19 different series or taxadjuncts identified by standard soil classification however 21 of the sgc soil types had only one or two representatives individual plots contained five to 11 different sgc soil types with extensive local variability a standard power function relationship between soil richness s and area or number of samples a provided the best fit for most plots s ca b the exponent b was slightly higher than for the taxonomy based analysis but in general the analyses lead to similar conclusions with respect to the relationship between richness and area and the relative importance of local within plot versus regional between plot variability results support the view that soils can be viewed and treated as discrete entities that richness assessments are not necessarily extremely sensitive to the classification used and that highly localized variability may be critical to pedodiversity the suggested criteria for identifying discrete soil types are given based on qualitative morphological differences and state factor relations contiguity and connectivity

spatial variations and bioaccumulation of heavy metals in intertidal zone of the yellow river estuary china nine units in new born intertidal zone of the yellow river estuary china were examined for concentrations of heavy metals pb cr cu zn and ni in sediments and plants heavy metal levels in surface sediments were in the order of zn pb approximate to cr cu approximate to ni and generally increased in a seaward direction except for z6 tamarix chinensis suaeda salsa zone and z7 s salsa t chinensis zone units significant differences in metal concentrations of the 9 units were observed in the profiles p cu pb ni cr and differed among plants or tissues the roots at z2 calamagrostis pseudophragmites zone z3 imperata cylindrical zone and z4 phramites australis zone units accumulated greater metals than shoots tfs translocation factors 1 implying that intertidal plants showed different pathways in metal accumulation and internal transportation except for pb the concentrations of cr cu zn and ni in sediments were lower than the criteria of class i recommended by the environmental quality standard for soils of china although heavy metal levels in intertidal zone were generally the lowest cr cu zn and ni or relatively moderate pb compared with other estuaries or bays in asia and europe high eco toxic risk of pb and ni exposure still could be observed at z4 z6 and z9 mudflat zone units s salsa was more suitable for the potential biomonitor or phytoremediation of all five heavy metals if intertidal sediments was seriously contaminated with increasing of pollutants loading in the yellow river estuary c 2014 elsevier b v all rights reserved

deglaciation of the younger dryas or loch lomond stadial ice field in the northern highlands scotland when viewed from the air scottish hummocky moraine can be resolved into a series of linear ridges that resemble those found at the margins of actively retreating glaciers today recent work has supported the interpretation of these linear ridges as ice marginal landforms and the authors believe that the majority of hummocky moraine deposits can be interpreted in this way consequently the pattern of deglaciation can be established fairly precisely from the pattern of linear ridges this approach is applied to the landforms of the northern part of the loch lomond stadial ice field in order to reconstruct the regional pattern of deglaciation this leads to important inferences about the significance of topographic control during deglaciation and more importantly it provides fresh insight into the environment of the british isles during the loch lomond stadial

diversity of diagnostic horizons in soils of the contiguous usa a case study abstract many previous studies of pedodiversity have emphasized the lateral variability of soils in this study the vertical distribution of diagnostic horizons is examined at the soil series level unlike genetic horizons diagnostic soil horizons are based on quantitatively defined morphological and analytical properties and they form the basis of modern soil classification systems an examination of 1600 soil series in 63 representative out of 226 major land resource areas mlras in contiguous usa revealed that they contain from one to seven diagnostic soil horizons with an average of 2 6 1 2 about 20 of the soil series contain 4 or more diagnostic horizons 80 of these soil series are in seven great groups the glossudalfs haplorthods fragiorthods endoaquods epiaquods fraglossudalfs and glossaqualfs the laurentide great lakes region contains a discordant number 57 of soils with 4 or more diagnostic horizons the most common being ochric 100 albic 91 argillic 85 glossic 69 spodic 51 and a fragipan 19 several factors appear to contribute to the diversity of diagnostic horizons including proximity to the great lakes where abundant snowfall precludes soil freezing and enables water to percolate rapidly through the soil in a short interval during the spring the prevalence of stratified glacial deposits often containing a lithologic discontinuity and a fluctuating water table all of which enable specific weathering products to accumulate at different depths

pedodiversity and global soil patterns at coarse scales with discussion several algorithms for analyzing the diversity of the world pedosphere are reviewed and employed special emphasis has been laid on indices based on the theory of information we study the diversity and distribution of major soil groups by continents and climatic zones on the basis of data compiled by the fao at the scale i 5 000 ooo major soil group distribution model relationships on a world level seem to follow more equitable patterns than those established for biocenoses and soil patterns at fine scales at a continental level the pedosphere s diversity is characterized by similarities rather than differences differences in diversity by climatic zones are more marked evenness pielou s index and diversity shannon s index tend to be greater in the climatic zones of intermediate latitudes than in circumequatorial and circumboreal latitudes the climatic zones closest to the poles could be the planet s most uniform soil patterns at small scales mountain areas in general achieve the highest pedorichness and lowest values of diversity global soil pattern distribution was also analyzed using multivariate techniques at a continental level it is possible for the structure of the global pedosphere to be determined by the continent s geological tectonic and climatic histories soil patterns of different climatic zones are linked in a very well defined latitudinal gradient

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

modern glacier characteristics as a basis for inferring former climates with particular reference to the loch lomond stadial abstract studies of the mass balance of modern glaciers have indicated that the equilibrium line altitude ela is the most critical parameter in the link between glaciers and climate average accumulation on a glacier includes components derived from direct precipitation on the glacier surface as well as wind drifting and avalanching of snow and approximates closely to accumulation at the equilibrium line ablation is most usefully predicted by mean summer temperature and there is a close non linear relationship between accumulation and mean summer temperature at the equilibrium line following discussion of methods of reconstructing former glaciers and calculating their equilibrium line altitudes the application of the above relationships to the loch lomond readvance glaciers of highland britain is considered and an outline of the precipitation pattern and the mean summer temperature of the loch lomond stadial is given

the quaternary deposits and landforms of scotland and the neighbouring shelves a review abstract a thick sequence of quaternary sediments up to 1000 m has been deposited in the north sea basin and perhaps five major glacial episodes the first occurring prior to ca 1 8 2 1 ma bp and the last during the late devensian can be recognised between the glacial events periods of low salinity arctic marine or glacio marine sedimentation have been dominant although episodes of ameliorated climate when north atlantic drift waters had access to the north sea have been identified a number of horizons in separate boreholes have been correlated with the last interglacial oxygen isotope stage 5e and a sequence of water mass movements around the scottish coasts can be reconstructed for the last ca 125 ka on land sequences of quaternary deposits relating to several glacial and non glacial terrestrial and marine events occur in different areas but due to poor dating correlation between these sequences cannot yet be achieved in particular north east scotland has a complex glacial history with evidence for ice sheet glaciation on at least four occasions evidence from the outer hebrides north east scotland and the north sea basin indicates that the late devensian scottish ice sheet had a rather restricted extent only reaching a short distance offshore along much of the east and west coasts at this time ice free areas existed in north east scotland on the isle of lewis and probably in caithness and orkney whilst part of the outer shelf around st kilda was dry land a marine embayment extended down the east coast of scotland between the scottish and scandinavian ice sheets and independent ice caps existed on the outer hebrides and probably on shetland deglaciation of the greater part of the country took place prior to ca 13 ka bp whilst the climate was still very cold the ice retreat appears to have been orderly with stagnant ice masses being trapped only in topographically suitable locations a number of retreat stages or minor readvances occurred during the general deglaciation the firth of clyde was one of the last areas outside the highlands to be deglaciated and this occurred in a rapid possibly catastrophic fashion shortly prior to ca 13 ka bp despite the mild climate at the start of the lateglacial interstadial it is not known if there was complete deglaciation prior to the loch lomond readvance the readvance glaciers however may have started to advance during the latter part of the interstadial when declining terrestrial temperatures coincided with a period of mild marine conditions the loch lomond readvance maximum can only be dated to some time after ca 10 9 ka bp and it is likely that final ice free conditions were not achieved until the earliest holocene

a sar record of early 21st century change in greenland glaciers in greenland are changing rapidly to better understand these changes we have produced a series of seven synthetic aperture radar sar backscatter mosaics for seven winters during the period from 2000 to 2013 six of the mosaics were created using radarsat fine beam data and the seventh used alos palsar fine beam single polarization data the radarsat mosaics are radiometrically calibrated and capture changes in the backscatter coefficient related to melt and other events particularly the strong melting in the summer of 2012 comparison of features in the ascending orbit alos mosaic and the descending orbit radarsat mosaics indicate that in areas of smooth to moderate topography their locations are consistent to within a few 10s of meters the locations of features identifiable in the radarat mosaics which were collected with the same imaging parameters generally agree to within better than the 20 m posting of the data with such geometric accuracy these data establish a record of change in greenland for the early part of the 21st century thus providing a baseline that can be compared with new radar and optical data sets

synchronisation of palaeoenvironmental events in the north atlantic region during the last termination a revised protocol recommended by the intimate group abstract the north atlantic intimate group of the inqua palaeoclimate commission has previously recommended an event stratigraphy approach for the synchronisation of records of the last termination using the greenland grip isotopic record as the regional stratotype and intcal98 for the calibration of radiocarbon dates lowe j j hoek w intimate group 2001 inter regional correlation of palaeoclimatic records for the last glacial interglacial transition a protocol for improved precision recommended by the intimate project group quaternary science reviews 20 1175 1187 here we present a revised protocol for time stratigraphic correlation in the north atlantic region over a more extended time period 30 8 ka this employs the new ngrip isotopic record and associated greenland ice core chronology 2005 gicc05 as the regional stratotype intcal04 for the calibration of radiocarbon dates bayesian based statistical procedures for the construction of age models and tephrochronology to validate correlations between regional site records

genesis of hummocky moraines by thrusting in glacier ice evidence from svalbard and britain irregular mounds of glacial debris commonly referred to as 9hummocky moraine9 until recently were linked to ice stagnation during rapid climatic amelioration however recent work in scotland has demonstrated that some hummocky moraine dating from the younger dryas event c 10 000 years bp was the product of deposition at active ice margins observations at modern high arctic glacier margins in svalbard 76 80 n indicate that some moraines of this type form under a dynamic glaciological regime mainly by thrusting in active polythermal ice undergoing strong longitudinal compression this situation is particularly common where there is a transition from warm based ice in the interior of a glacier to cold based ice at the margins or snout from their morphological similarity rectilinear slopes facing up glacier and irregular downglacier faces and apparent stacking of slabs of sediment of subglacial derivation it is concluded that some assemblages of british moraines are also the product of thrusting this process appears to be most dominant in polythermal glaciers rather than in temperate glaciers on this basis it is tentatively suggested that the younger dryas in britain was characterized by a climatic regime similar to that in svalbard today mean annual temperature 5 c 400 1000 mm precipitation and that the associated glaciers may have been of polythermal character

application of a degree day model to reconstruct pleistocene glacial climates there is empirical evidence of a nonlinear relation between annual precipitation or accumulation and summer mean temperature at the equilibrium line altitude ela on glaciers around the world the degree day model gives a similar relation between accumulation and summer temperature although instead of a single universal curve there is a family of curves depending upon the annual temperature range furthermore the degree day model also gives nonlinear relations between accumulation and annual mean temperature thus estimations of accumulation can be made from both summer and annual temperatures at the ela of former reconstructed glaciers such as those in greece this is particularly useful since these climatic variables have major implications for biological proxies such as vegetation history indicated in the pollen record and for periglacial proxies such as permafrost distributions indicated in the geomorphological record the close relationship between glaciers and climate provides one of the most precise methods for reconstructing former climates and offers considerable potential for resolving our understanding of pleistocene cold stage climates

cosmogenic 10be and 26al exposure ages of tors and erratics cairngorm mountains scotland timescales for the development of a classic landscape of selective linear glacial erosion abstract the occurrence of tors within glaciated regions has been widely cited as evidence for the preservation of relic pre quaternary landscapes beneath protective covers of non erosive dry based ice here we test for the preservation of pre quaternary landscapes with cosmogenic surface exposure dating of tors numerous granite tors are present on summit plateaus in the cairngorm mountains of scotland where they were covered by local ice caps many times during the pleistocene cosmogenic 10be and 26al data together with geomorphic relationships reveal that these landforms are more dynamic and younger than previously suspected many cairngorm tors have been bulldozed and toppled along horizontal joints by ice motion leaving event surfaces on tor remnants and erratics that can be dated with cosmogenic nuclides as the surfaces have been subject to episodic burial by ice an exposure model based upon ice and marine sediment core proxies for local glacial cover is necessary to interpret the cosmogenic nuclide data exposure ages and weathering characteristics of tors are closely correlated glacially modified tors and boulder erratics with slightly weathered surfaces have 10be exposure ages of about 15 to 43 ka nuclide inheritance is present in many of these surfaces correction for inheritance indicates that the eastern cairngorms were deglaciated at 15 6 0 9 ka glacially modified tors with moderate to advanced weathering features have 10be exposure ages of 19 to 92 ka these surfaces were only slightly modified during the last glacial cycle and gained much of their exposure during the interstadial of marine oxygen isotope stage 5 or earlier tors lacking evidence of glacial modification and exhibiting advanced weathering have 10be exposure ages between 52 and 297 ka nuclide concentrations in these surfaces are probably controlled by bedrock erosion rates instead of discrete glacial events maximum erosion rates estimated from 10be range from 2 8 to 12 0 mm ka with an error weighted mean of 4 1 0 2 mm ka three of these surfaces yield model exposure plus burial ages of 295 71 84 520 141 178 and 626 85 102 ka a vertical cosmogenic nuclide profile across the oldest sampled tor indicates a long term emergence rate of 31 2 mm ka these findings show that dry based ice caps are capable of substantially eroding tors by entraining blocks previously detached by weathering processes bedrock surfaces and erratic boulders in such settings are likely to have nuclide inheritance and may yield erroneous too old exposure ages while many cairngorm tors have survived multiple glacial cycles rates of regolith stripping and bedrock erosion are too high to permit the widespread preservation of pre quaternary rock surfaces

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

phosphatized volcanic soils of fernando de noronha island brazil paleoclimates and landscape evolution abstract volcanic oceanic islands host soils that may hold important paleo environmental proxies based on vegetation and faunal evidences coupled with pedological and geomorphological indicators in this regard the main brazilian oceanic island of fernando de noronha fni still lacks a deeper and more complete analysis of its climatic history and soil evolution we select and collect representative fni soils to interpret their chemical physical and mineralogical properties and to explain their changing pedogenesis and geomorphic balance aiming at revealing the environmental and landscape evolutionary history of this island ten soil pedons on phonolites ankaratrites and the associated pyroclastic rocks were collected in june 2018 six profiles were classified as inceptisols one as entisol one as mollisol one as vertisol and another as the first oxisol ever described in a brazilian oceanic island the ph ranged between 5 0 and 6 0 in the more developed dystrophic and al saturated soils whereas alkaline phs were found in the eutrophic and na rich pedons for the latter group chemical and physical attributes are closely associated with the parent material composition whereas in the former present day soil features overprint paleoweathered regoliths and former pedogenetic processes high concentrations of available phosphorus p were observed in all soils and horizons even at depths greater than 150 cm and p forms were detected as amorphous or poorly crystalline phosphates al fe na ca and k high and low activity clay minerals coexist combined with gibbsite and unstable primary minerals indicating the polygenetic nature of fni soils a combined pedogeomorphological analysis indicated the existence of a high paleoweathered plateau with relict soils and erosional surfaces hosting younger soils results showed the succession of at least three distinct main paleoclimates since the pliocene and a post magmatic model for landscape evolution the unreported widespread and intense phosphatization of all soils and paleosurfaces is attributed to a past large population of birds nesting all over the island corroborating old historical records of the island s early occupation report the occurrence of brazil s first ornithogenic oxisol with more than 500 mg kg of bioavailable p

glacier response to climatic change during the loch lomond stadial and early flandrian geomorphological and palynological evidence from the isle of skye scotland the deglaciation of skye at the close of the loch lomond stadial is assessed on the basis of detailed geomorphological mapping and pollen stratigraphic correlations it is concluded that deglaciation proceeded in two distinct stages the first was marked by numerous glacier stillstands and readvances while uninterrupted retreat and local glacier stagnation occurred during the second and final stage the pollen evidence indicates that the first stage was well advanced before the marked thermal improvement at the start of the flandrian and it is inferred that initial glacier retreat occurred in response to a decline in precipitation in the later part of the loch lomond stadial the first stage of glacier retreat continued into the early flandrian during which climatic amelioration was interrupted briefly final deglaciation appears to have occurred rapidly in response to sustained temperature increases the collective evidence also indicates spatial variations in the timing of deglaciation which appear to reflect differences in glacier morphology

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