a scottish speleothem record of the h 3 eruption or human impact a comment on baker smart barnes edwards and farrant studies of a stalagmite sample from sutherland scotland have identified a period of enhanced growth that lasted for four years and has been dated to 1135 130 bc baker et al 1995 this episode is unique within this sample and has not been observed elsewhere the authors correlate it with the icelandic volcanic eruption at 1021 130 100 bc that produced the hekla 3 h 3 tephra there is however no direct evidence for a causal relationship between volcanic activity in general or the h 3 eruption in particular and the growth patterns of the stalagmite as an alternative to the volcanic explanation of enhanced growth we suggest that the speleothem could reflect environmental changes associated with woodland decline and the spread of blanket peat

holocene paleoceanography of the northwest passage canadian arctic archipelago abstract a series of cores box and piston were collected at 2 key locations in lancaster sound cores 2004 804 009 bc and pc and barrow strait cores 2005 804 004 bc and pc in the canadian arctic archipelago to document the evolution of sea surface conditions in the main axis of the northwest passage during the holocene time period reconstruction of sea surface parameters summer temperature and salinity duration of sea ice cover were estimated based on transfer functions using dinoflagellate cyst assemblages as proxy indicators the chronology of these cores is based on calibrated ams 14c dates 210pb analyses and correlations between paleomagnetic secular variations of the geomagnetic field and a predicted spherical harmonic model of the geomagnetic field cals7 k 2 our age models for both cores indicate that 009 pc spans the last 11 100 cal bp while 004 pc encompasses the last 10 800 cal bp calculated sedimentation rates are in the range of 43 140 cm kyr for core 009 pc and 15 118 cm kyr for core 004 pc allowing for a millennial time scale resolution in each core our results indicate relatively harsh conditions in lancaster sound between 10 800 and 9000 cal bp summer temperatures 2 c cooler than at present which we associate with the presence of active ice streams in northernmost baffin bay and a weak west greenland current this is followed by a warming trend up to 3 c higher than present that took place between 8500 and 5500 cal bp which we associate with the holocene thermal maximum and to a large scale atmospheric pattern such as the arctic oscillation operating at the millennial time scale this is concomitant with an increase in the relative abundance of phototrophic dinoflagellate cyst taxa a gradual cooling of sea surface temperature and increased sea ice follow this from 5500 cal bp until the modern period in barrow strait harsh sea surface conditions prevailed from 11 100 to 5500 cal bp with summer temperatures as low as 4 c cooler than at present the warming trend occurred later in this region between 5500 and 1000 cal bp after which a gradual cooling is observed until the modern period the apparent shift or opposite warming trends between lancaster sound and barrow strait after 5500 cal bp could be the result of a change in atmospheric circulation patterns related to a possible shift in the ao mode from ao to ao comparison of ice core 18o record from devon island ice cap and the reconstructed sea surface temperature from core 009 pc suggests a strong atmospheric oceanic coupling throughout the holocene in this area

speleothem u th age constraints for the last glacial conditions in the apuan alps northwestern italy abstract during the quaternary several glaciations occurred in the mountain regions around the mediterranean and in recent years new ages have better constrained their timing however this is not the case for the apuan alps a high rainfall mountain chain adjacent to the mediterranean sea here in spite of the widespread evidence for glaciers the complete lack of geochronological information hinders our understanding of glaciation history in this paper we utilize speleothem ages to better constrain the timing of these glacial features we re examine 293 uranium thorium ages from 19 speleothems collected in five caves at different elevations after a period of very low growth between 160 and 132 ka the analysed speleothems grew almost continuously to 75 ka this period was followed by intermittent growth with lower deposition rate and presence of hiatuses until 12 5 12 ka this is consistent with an ice coverage persisting over the apuan alps inhibiting or interrupting the growth of speleothems via the limited availability of groundwater and the scarcity absence of soils this interval is much greater than the time interval that has previously been attributed to the existence of glaciers on the apuan alps which has been assumed to be restricted to marine isotope stage mis 2 instead ice cover probably also appeared in the apuan alps during mis 4 the phase of restarting of growth which may implies the definitive or substantial glacier melts seem to predate the holocene

high resolution paleomagnetic dating of sediments deposited in the central baltic sea during the last 3000 years abstract sediment cores from the main sedimentary basin in the baltic sea the gotland deep provide a high resolution record of changes in the holocene paleo environment and paleoclimate due to the inherent inaccuracy reservoir effect redeposited material of the 14 c dating method in dating marine sediments the known changes in the earth s magnetic field recorded in three sediment cores from the gotland deep were used to produce a more detailed and accurate timescale the variations in the inclination and declination were compared to the paleosecular variations over the last 3000 years recorded in annually laminated lake sediments from finland this correlation made it possible to construct for the late holocene gotland deep sediments a high resolution time scale with an estimated absolute accuracy of better than 50 years this new timescale made it possible to determine the mean annual rates of sedimentation with an unprecedented accuracy the sedimentation rates were found to have varied considerably both in time from 0 2 up to 4 3 mm year and space indicative of the patchy nature of accumulation in the gotland deep during the past 3000 years

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

speleothems as high resolution paleoflood archives abstract over the last two decades speleothems have become widely utilized records of past environmental variability typically through their stable isotopic and trace elemental chemistry numerous speleothem researchers have identified evidence of flooding recorded by detrital layers trapped within speleothems but few studies have developed paleoflood reconstructions from such samples because they can be precisely dated are generally immune to post depositional distortion or erosion and can be tied to a fixed elevational baseline speleothems hold enormous potential as high resolution archives of cave floods and thus as proxies for extreme rainfall or other hydrologic drivers of cave flooding here we review speleothem based paleoflood reconstruction methods identify potential biases and pitfalls and suggest standard practices for future studies

geomagnetic secular variation as recorded in british lake sediments and its application to archaeomagnetic studies abstract lake sediments can play an important role in understanding and reconstructing temporal characteristics of the geomagnetic field as they potentially offer near continuous high resolution archives of magnetic information extending throughout the holocene to date lake sediment geomagnetic data has typically been excluded from british archaeomagnetic secular variation curves svc due to uncertainties with the acquisition of magnetisation by lake sediments this paper presents the argument that with regards to british datasets the real problem lies with poor chronological control and sets out to illustrate that with british archaeomagnetic data some progress has been made the results indicate that it is not currently possible to resolve secular variation on a time scale of 100 years from published british lake sediment data but more success has been made with data from archaeological sediments this level of detail has been considered necessary for the incorporation of lake sediment data into the british archaeomagnetic dataset as the ability to resolve short term geomagnetic changes is critical for the integration of any dataset into the british svc as the latter is predominantly employed to date archaeological architecture and artefacts requires that it has the ability to resolve changes over timescales relevant to human lifetimes using currently available data this retrospective critique confirms that in archaeological sediments depositional and thermoremanent magnetisation can record the same direction over the same time interval

new data on speleothem deposition and palaeoclimate in britain over the last forty thousand years 230th 234u dates are presented for 26 speleothems from three areas in britain assynt n w scotland n w yorkshire mendip hills somerset these dates suggest that speleothem growth was widespread but rare in the period from 40 to 26 ka absent from 26 to 15 ka and abundant from 15 ka to the present the absence of speleothems between 26 and 15 ka is attributed to glaciation in yorkshire and assynt and tentatively to continuous permafrost development in the mendip hills the occurrence of speleothems before 26 ka places restrictions on the extent of any ice sheet which may have been present in scotland and indicates that n w scotland was not subjected to continuous permafrost at that time

a possible mechanism for growth of calcite speleothems without participation of biogenic carbon dioxide abstract using plummer et al s 11 rate equations on the dissolution and deposition of caco3 in h2o co2 systems we have calculated deposition rates of caco3 to stalagmites in caves which are covered by glaciers or bare karst in this case no biogenic co2 from vegetated soil is available and the deposition of caco3 involves only atmospheric co2 the mechanism of deposition proceeds by a temperature effect cold melting waters of about 0 c dissolve caco3 under open system conditions at the surface of the rock when this solution saturated with respect to caco3 flows through the limestone rock its temperature increases by several degrees therefore it becomes supersaturated and caco3 is deposited under open system conditions in the warmer cave maximal growth rates of about 10 3 cm year are possible from the kinetics of the deposition of caco3 from the thin water films present at the surface of stalagmites we are able to estimate the isotopic composition of carbon in the caco3 deposited on the stalagmites to be approximately 13c 8 which is close to some observed values from our data we conclude that substantial growth of stalagmites is possible during glacial periods as well as in areas of bare karst a question which was not resolved up to now

the last ice sheet in north west scotland reconstruction and implications recent models of the last scottish ice sheet suggest that nunataks remained above the ice surface in areas peripheral to the main centres of accumulation this proposition has been investigated on 140 mountains over an area of 10 000 km2 in nw scotland outside the limits of the later loch lomond readvance in this area there is evidence for a single high level weathering limit that separates glacially eroded terrain from higher areas of in situ frost debris this limit occurs at altitudes ranging from 425 to 450 m in the outer hebrides to 950 m on the mainland and is best developed on lithologies that resisted breakdown after ice sheet downwastage interpretation of this weathering limit as a periglacial trimline cut by the last ice sheet at its maximum thickness is supported by 1 joint depth and schmidt hammer measurements that indicate significantly more advanced rock breakdown above the weathering limit 2 a much greater representation of gibbsite a pre late devensian weathering product in the clay fraction of soils above the limit 3 cosmogenic isotope dating of the exposure ages of rock outcrops above and below the limit 4 the sharpness of the limit at some sites and its regular decline along former ice flowlines and 5 shear stress calculations based on the inferred altitude and gradient of the former ice surface reconstruction of the ice surface based on trimline evidence indicates that the mainland ice shed lay near or slightly east of the present watershed and descended northwards from 900 m to ca 550 m at the north coast independent dispersion centres fed broad ice streams that occupied major troughs on skye an ice dome 800 m deflected the northwestwards movement of mainland ice but the mountains of rum were over ridden by mainland ice up to an altitude of ca 700 m the outer hebrides supported an independent ice cap that was confluent with mainland ice in the minches extrapolation of the trimline evidence indicates that most reconstructions of ice extent are too conservative and suggests that low gradient ice streams extended across the hebridean shelf offshore wider implications of this research are 1 that blockfields and other periglacial weathering covers are not all of the same age or significance depending on the resistance of different lithologies to frost weathering 2 that the contrasting degree of glacial modification in the western and eastern highlands of scotland may reflect a former cover of predominantly warm based ice in the former and predominantly cold based ice in the latter and 3 that the approach and techniques developed in this study have potential application for constraining ice sheet models not only in areas peripheral to the main centres of ice accumulation in britain and ireland but also in other mountain areas where nunataks protruded through warm based late pleistocene ice masses

dating of late pleistocene interglacial and interstadial periods in the united kingdom from speleothem growth frequency abstract the growth of speleothems is indicative of interglacial and interstadial conditions in the united kingdom since their growth is dependent on two factors first the occurrence of significant diffuse groundwater recharge and second the biogenic production of carbon dioxide in the soil both are dependent on temperature and water availability the growth frequency of speleothems is examined using a cumulative distributed error frequency method applied to 341 uncontaminated uranium series age determinations the curves derived are shown to be statistically stable and the ages of the peaks are interpreted as the best estimates of the ages of interglacial and interstadial periods ten such periods are recognized during the interval 220 000 to 20 000 yr b p considerably more than are currently recognized in the uk pollen and coleoptera based quaternary stratigraphy correlations between the speleothem growth frequency peaks and last interglacial ipswichian sites can be made but correlations with last glacial devensian interstadial sites are limited because of the paucity of dates the speleothem growth frequency record provides a well dated terrestrial chronology for the past 140 000 yr b p which directly reflects regional palaeoclimatic conditions in britain and should prove very useful in unravelling the complex stratigraphy of the devensian and ipswichian stages

paleosecular variations recorded by holocene pleistocene sediments from lake el trebol patagonia argentina paleomagnetic studies carried out on six cores from the bottom sediments from lake el trebol south argentina are described measurements of directions declination and inclination d and i and intensity of natural remanent magnetisation nrm magnetic susceptibility at low and high frequency specific x and volumetric k isothermal remanent magnetisation irm saturation isothermal remanent magnetisation sirm back field and anhysteric remanent magnetisation arm were carried out stability of the nrm was investigated by alternating field demagnetisation rock magnetic studies suggest that the main carriers of magnetisation are ferrimagnetic minerals predominantly pseudo single domain magnetite records of nrm and k show a good correlation with the sedimentological description and also with those of shorter cores previously studied the tephra layers were identified from the lithologic profiles and also from the magnetic susceptibility logs due to their different chronological meaning and their rather bad behaviour as magnetic recorder these layers were removed from the sequence and the gaps that were produced along the profiles by the removal were closed obtaining a shortened depth radiocarbon age estimates from these cores and from earlier studies allow us to construct a paleosecular variation psv record for the past 24 000 years these results show good correlation with the previous one the spectrum obtained from spectral analysis shows major peaks at periodicities of about 1150 1500 2490 3630 5240 and 11 810 years both clockwise and counterclockwise precession of the geomagnetic vector is evident from analysis of the bauer plots with a preponderance of clockwise movement

historical climatic record from flood sediments deposited in the interior of spiralka cave czech republic abstract magnetic susceptibility was measured on more than four hundred samples collected from a 5 m high section of fine grained sediments deposited during flood events in the interior of spiralka cave spiralka cave is located in the northeastern portion of the moravian karst czech republic in the upper 1 5 m of this profile mineral magnetic fe arm sirm s ratio t and other non magnetic measurements heavy mineral concentration loss on ignition and particle grain size indicate that variations are controlled by the concentration of magnetite and by magnetic grain size i e increased magnetic susceptibility results from increased concentration of coarse grained magnetite a positive correlation with ti and zr concentrations in this part of the profile with our magnetic susceptibility record is a detrital signal responding to changing environmental conditions in the catchment area furthermore a comparison of our susceptibility record to the record of winter temperature anomalies constructed from both instrumental and historical records collected at the klementinum observatory in prague shows a remarkable correlation the most probable explanation of these correlations is that during years with warmer winters positive winter temperature anomalies and less snow cover the floods were less intensive but probably had access to larger tracts of cultivated land as agriculture tended to expand during these warmer periods cultivation of the land provided flood waters with greater access to coarser grained magnetite like materials exposed by tilling of soils lower in the profile interpreting the environmental significance of magnetic susceptibility variations is more complex as remobilization of iron has occurred nevertheless the magnetic susceptibility record when coupled with non magnetic measurements can be shown to correlate to known environmental conditions present in central europe during the deposition of the lower portion of the profile

holocene sea ice history and climate variability along the main axis of the northwest passage canadian arctic 1 palynological geochemical and physical records were used to document holocene paleoceanographic changes in marine sediment core from dease strait in the western part of the main axis of the northwest passage core 2005 804 006 pc latitude 68 59 552 n longitude 106 34 413 w quantitative estimates of past sea surface conditions were inferred from the modern analog technique applied to dinoflagellate cyst assemblages the chronology of core 2005 804 006 pc is based on a combined use of the paleomagnetic secular variation records and the cals7k 2 time varying spherical harmonic model of the geomagnetic field the age depth model indicates that the core spans the last 7700 cal years b p with a sedimentation rate of 61 cm ka 1 the reconstructed sea surface parameters were compared with those from barrow strait and lancaster sound cores 2005 804 004 pc and 2004 804 009 pc respectively which allowed us to draw a millennial scale holocene sea ice history along the main axis of the northwest passage manwp overall our data are in good agreement with previous studies based on bowhead whale remains however dinoflagellate sea surface based reconstructions suggest several new features the presence of dinoflagellate cysts in the three cores for most of the holocene indicates that the manwp was partially ice free over the last 10 000 years this suggests that the recent warming observed in the manwp could be part of the natural climate variability at the millennial time scale whereas anthropogenic forcing could have accelerated the warming over the past decades we associate holocene climate variability in the manwp with a large scale atmospheric pattern such as the arctic oscillation which may have operated since the early holocene in addition to a large scale pattern more local conditions such as coastal current tidal effects or ice cap proximity may have played a role on the regional sea ice cover these findings highlight the need to further develop regional investigations in the arctic to provide realistic boundary conditions for climatic simulations

a paleomagnetic record from lake lama northern central siberia abstract two cores from lake lama northern central siberia with lengths of 19 and 11 m respectively were subjected to detailed magnetostratigraphic investigations directions of the characteristic remanent magnetisation chrm were derived from vector analysis of the results from alternating field a f demagnetisation yielding records for the last 18 000 years bp the sediments show a distinct change in sedimentation pattern at around 14 500 years bp from a highly variable to a monotonous sedimentation with anoxic conditions in the lake sediments during the last 11 500 years bp the oxic anoxic boundary is reflected in all rock magnetic parameters measured and the magnetic mineral fraction is affected by reductive dissolution of iron bearing minerals here mainly magnetite therefore no record of relative paleointensity could be achieved but as intra and inter lake comparison of the obtained inclination and declination records have shown the directions of the geomagnetic field recorded in the sediments from lake lama were not severely affected by the partial dissolution of the remanence carrying minerals

palaeomagnetic dating of late holocene sediments in fennoscandia abstract palaeomagnetic secular variation curves that have been dated by varve analysis counting annual laminations are used to date four holocene lacustrine sediment sequences from central finland and northwest russia lat 62 66 n several fine scale geomagnetic declination and inclination fluctuations can be identified during the last 3200 yr which is the most accurately dated interval in the present data relative palaeomagnetic dating is a powerful dating tool for sediments of large and deep lakes in northern europe which are difficult to date using the 14 c method because of low organic content contamination by older carbon and or scarcity of terrestrial macrofossils suitable for ams 14 c dating the dating error during the last 3200yr is estimated to be less than 50 yr such accuracy is not readily attainable using other methods

new constraints on the age of the last ice sheet glaciation in nw england using optically stimulated luminescence dating optically stimulated luminescence osl has been used to date silts interpreted as either primary or colluviated loess deposited in karstic depressions at three sites on the carboniferous limestone of nw england two of the ages presented here constrain the onset of the last late devensian ice in this region to later than ca 27 2 ka and the other two date initial deglaciation prior to ca 19 2 ka in the morecambe bay area and ca 17 2 ka in the karst of the yorkshire dales while these ages are broadly consistent with existing estimates from lacustrine and speleothem evidence they offer the tightest constraints yet published on the presence of the last ice sheet from northern england copyright 2009 john wiley sons ltd

estimating hydrogeological conditions over the last 120 ka an example from the sellafield area uk for a number of years united kingdom nirex limited investigated the suitability of the area around sellafield in nw england to assess its suitability to host a deep repository for intermediate level and some low level radioactive wastes resulting from britain9s nuclear programme the investigation programme collected a large amount of lithological hydrogeological and hydrochemical data from 18 boreholes up to 2000 m deep a potential route by which radionuclides may leave the repository and return to surface is the groundwater pathway it was recognized that the groundwater regime could be disturbed significantly by major climate changes particularly glacial interglacial cycles over the very long time scales considered in the assessment of the radiological safety of a repository available geological and hydrogeological data for the sellafield area are reviewed in the context of current thinking on glacial hydrogeology showing that disturbance of the hydrogeological regime is possible during glaciation and that there are significant uncertainties in determining the timing and magnitude of the effects caused by glaciation however the evidence available both from quaternary fracture filling minerals and from the chemistry of groundwater now present suggests that any disturbance to the deeper hydrogeological regime was relatively minor and that any subglacial recharge has been removed by the present flow regime there is a possibility that high hydraulic heads at depth in the low permeability basement rock considered as a host for the repository the borrowdale volcanic group of ordovician age beneath a cover of triassic sandstones may be residual

stable isotopes in charophyte incrustations relationships with climate and water chemistry abstract age gradients of stable c and o isotopes were found in modern chara hispida calcite incrustations allowing seasonal changes in water chemistry to be observed gradients resulted from apical calcification in growing charophytes in a regional study of 12 species and varieties of charophytes the carbonate 13c differed significantly with low value and high value species such as chara globularis and c baltica respectively samples from lakes and other stagnant waters had significantly higher 13c values than those sampled from flowing water the differences were related mainly to photosynthesis charophyte 18o carbonate was not significantly different between species but water chemistry was important for brackish water lamprothamnium papulosum the overall 18o carbonate was positively correlated with groundwater 18o and it is suggested that more reliable environmental information is available from 18o than 13c in charophyte marls the mean charophyte carbonate 13c and 18o was 5 7 and 6 4 vpdb respectively environmental temperature estimates suggested that at some sites the carbonate was deposited close to isotopic equilibrium but in others a slight to moderate disequilibrium was indicated

holocene comment and reply hekla 4 ash the pine decline in northern ireland and the effective use of tephra isochrones a comment on hall pilcher and mccormac in response to a paper by blackford et al 1992 which showed a coincidence between the deposition of hekla 4 tephra and a decline of pinus pollen in two northern scottish sites hall et al 1994 investigated the tephra pine pollen relationship at two sites in northern ireland we argue that their sites are inappropriate for such comparison because pine was effectively absent from co antrim long before the deposition of hekla 4 the opportunity is taken to make some additional points concerning the irish data and the wider use of tephra isochrones

rate of glacial valley deepening during the late quaternary in assynt scotland a dated landscape history of the allt nan uamh valley in the assynt area is constructed spanning the last 300 ka using geomorphological analysis u series speleothem dating and existing cave surveys the mean rate of valley deepening is estimated to lie between 47 and 68 m per glacial interglacial cycle of 100 ka this combined with an estimated duration of glaciation implies glacial erosion rates of about 2 mm a 1 in agreement with modern process measurements 1997 by john wiley sons ltd

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

northwest european palaeoclimate as indicated by growth frequency variations of secondary calcite deposits a compilationn for the northwest of europe of over 500 uranium series speleothen and travertine dates is presented using a cumulative distributed error frequency approach these secondary carbonate deposits require both significant groundwater supply and a biogenic soil carbon dioxide source for their growth during glacial periods soil co2 production is inhibited and the water supply is ice locked therefore growth is slowed significantly if not stopped thus deposits can be used on a chronological basis to give a signal of glacial and non glacial periods however sensitivity to the groundwater supply modifies this signal with growth also limited in times of high aridity the palaeoclimatic signal is thus complex the compilation presented is used both as a chronology for comparison with the orbitally tuned marine oxygen isotope record and as a palaeoclimatic indicator attention is focused on two periods of the last glacial interglacial cycle where the record provides a significantly different palaeoclimatic record to other terrestrial and oceanic records these are the isotope stages 5 4 transition for which a relatively low cumulative growth frequency indicates an earlier increase in aridity than observed elsewhere and isotope stage 3 the pleniglacial where both statistically significant high 49 62 ka and low 22 35 44 46 ka levels of growth are observed and can be used to constrain the timing of many of the interstadial events within this period

testing the fidelity of sediment chronology comparison of varve and paleomagnetic results from holocene lake sediments from central finland abstract a careful construction of independent varve and paleomagnetic chronologies from three varved lake sediment records from central finland resulted in detailed and continuous age depth profiles cumulative varve calculation errors were estimated to be 3 for lake alimmainen savijarvi 10 295 340 varve years and 1 for lakes nautajarvi 9898 97 varve years and korttajarvi 9590 103 varve years paleomagnetic secular variation psv curves demonstrate good consistency between these sites and within a margin of varve chronology error they show similar declination and inclination features commonly described in the uk and sweden the timing of psv patterns from finnish varved sites agree well with uk curves between the present and 2000 bc and in pre 6000 bc deposits and with swedish data between the present and 5000 bc combined inclination records from three independently dated finnish varved sites possess an opportunity for accurate paleomagnetic comparisons within the margin of varve chronology errors and throughout the last 10 000 years

dynamic recrystallization near the brittle plastic transition in naturally and experimentally deformed quartz aggregates the electron backscattering diffraction technique ebsd was used to analyze bulging recrystallization microstructures from naturally and experimentally deformed quartz aggregates both of which are characterized by porphyroclasts with finely serrated grain boundaries and grain boundary bulges set in a matrix of very fine recrystallized grains for the tonale mylonites we investigated a temperature range of 300 380 c 0 25 gpa confining pressure a flow stress range of 0 1 0 2 gpa and a strain rate of 10 13 s 1 were estimated experimental samples of black hills quartzite were analyzed which had been deformed in axial compression at 700 c 1 2 1 5 gpa confining pressure a flow stress of 0 3 0 4 gpa a strain rate of 10 6 s 1 and to 44 to 73 axial shortening using orientation imaging we investigated the dynamic recrystallization microstructures and discuss which processes may contribute to their development our results suggest that several deformation processes are important for the dismantling of the porphyroclasts and the formation of recrystallized grains grain boundary bulges are not only formed by local grain boundary migration but they also display a lattice misorientation indicative of subgrain rotation dynamic recrystallization affects especially the rims of host porphyroclasts with a hard orientation i e with an orientation unsuitable for easy basal slip in addition dauphine twins within porphyroclasts are preferred sites for recrystallization we interpret large misorientation angles in the experimental samples which increase with increasing strain as formed by the activity of fluid assisted grain boundary sliding

evidence of episodic coastal change during the late holocene the dungeness barrier complex se england plater a j stupples p roberts h m 2009 evidence of episodic coastal change during the late holocene the dungeness barrier complex se england geomorphology 104 1 2 47 58

periodic variations in late pleistocene speleothem abundance in britain abstract temporal change in the growth of speleothems in the united kingdom during the past 150 000 years is shown to be related to the insolation variation by the milankovitch theory the speleothem data compiled by gordon et al 1989 quarternary research 31 14 26 have two milanokovitch frequencies the ca 40 000 yr period related to change in the earth s obliquity and the ca 20 000 yr period related to the precession of the equinoxes the abundance of speleothem growth was in general large during the last interglaciation and small during the last glaciation in both periods however speleothem abundance was greater during periods of strong insolation and less during weak insolation

wolverine in northern england at about 83 000 yr b p faunal evidence for climatic change during isotope stage 5 abstract cave sediments from stump cross cave in northern england contain pleistocene mammal remains uranium series dating of calcium carbonate deposits closely associated with the fossiliferous horizons has established an absolute age of 83 000 6000 yr b p for a faunal assemblage largely comprised of wolverines gulo gulo this date lies firmly within the younger portion of oxygen isotope stage 5 the occurrence of wolverines in the vicinity of stump cross cave at ca 83 000 yr b p indicates a significant climatic deterioration from ca 120 000 yr b p when an ipswichian interglacial fauna with hippopotamus was present in this part of northern england

surface exposure dating 36cl and 10be of post last glacial maximum valley moraines lake district northwest england some issues and implications surface exposure ages 36cl and 10be have been obtained from 16 boulders at the margins of and within the limits of former valley glaciers at four sites in the lake district northwest england the established view is that the lake district functioned as an independent centre of ice dispersal during the last glacial maximum lgm 26 21 ka of the dimlington stade greenland stades 2 3 and that the glacial depositional landforms at the sampled sites are products of stillstands or readvances of the ice margins following the lgm however several of the apparent 36cl surface exposure ages pre date rather than post date the lgm it is inferred that these boulders retain levels of 36cl inherited from a previous period of exposure rather than indicating moraine formation prior to the lgm and their subsequent survival beneath lgm ice an implication is that lake district glaciers achieved limited erosion of bedrock during the build up to and at the maximum of the lgm and that glacial erosion rates increased at a late stage in that period single 36cl and 10be exposure ages from two sites suggest a stillstand or readvance of valley glaciers prior to the loch lomond younger dryas stade lls greenland stade 1 and windermere lateglacial interstade greenland interstade 1 but additional ages are required in order to confirm or refute these individual ages an lls age for glacial depositional landforms at both these sites had previously been proposed 36cl surface exposure ages for boulders on moraines within the lls limit do not fully support emplacement at that time there is a possibility that these moraines are associated with a pre lls stillstand or readvance of the valley glacier copyright 2013 john wiley sons ltd

palaeoclimate determination from cave calcite deposits calcite deposits formed in limestone caves have been found to be an excellent repository of palaeoclimatic data for terrestrial environments the very presence of a relict deposit indicates non glacial conditions at the time of formation and both 14c and uranium series methods can be used to date the deposit and hence the age of these climatic conditions variations in 13c and 18o content of the calcite in 2h and 18o content of fluid inclusions in trace element concentrations and more recently in pollen assemblages trapped in the calcite are all potentially available as synchronous palaeoclimatic indicators previous work has tended to concentrate mainly on abundance of deposits as a palaeoclimatic indicator for the last 300 000 years this literature is briefly reviewed here together with the theory and methods of analysis of the u series and stable isotopic techniques the combined use of u series ages and 13c and 18o variations in cave calcites illustrates the potential for palaeoclimate determination previously unpublished results of stable isotopic variations in dated calcites from caves in northern england indicate the level of detail of stable isotopic variations and time resolution that can be obtained and the complexity of interpretation that may arise tentative palaeoclimatic signals for the periods 90 125 ka and 170 300 ka are presented more comprehensive studies are needed in future work especially in view of the difficulty in obtaining suitable deposits and the ethics of cave deposits conservation