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

ice sheet sources of sea level rise and freshwater discharge during the last deglaciation we review and synthesize the geologic record that constrains the sources of sea level rise and freshwater discharge to the global oceans associated with retreat of ice sheets during the last deglaciation the last glacial maximum 26 19 ka was terminated by a rapid 5 10 m sea level rise at 19 0 19 5 ka sourced largely from northern hemisphere ice sheet retreat in response to high northern latitude insolation forcing sea level rise of 8 20 m from 19 to 14 5 ka can be attributed to continued retreat of the laurentide and eurasian ice sheets with an additional freshwater forcing of uncertain amount delivered by heinrich event 1 the source of the abrupt acceleration in sea level rise at 14 6 ka meltwater pulse 1a 14 15 m includes contributions of 6 5 10 m from northern hemisphere ice sheets of which 2 7 m represents an excess contribution above that derived from ongoing ice sheet retreat widespread retreat of antarctic ice sheets began at 14 0 15 0 ka which together with geophysical modeling of far field sea level records suggests an antarctic contribution to this meltwater pulse as well the cause of the subsequent younger dryas cold event can be attributed to eastward freshwater runoff from the lake agassiz basin to the st lawrence estuary that agrees with existing lake agassiz outlet radiocarbon dates much of the early holocene sea level rise can be explained by laurentide and scandinavian ice sheet retreat with collapse of laurentide ice over hudson bay and drainage of lake agassiz basin runoff at 8 4 8 2 ka to the labrador sea causing the 8 2 ka event

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

a lateglacial 10be production rate from glacial lake shorelines in scotland the identification of tephra within varved deposits of a former ice dammed lake that existed in scotland during the younger dryas provides an opportunity to calibrate 10be production rates using previously published 10be concentrations from the lake shoreline and independently derived ages for the tephras derived from the greenland ice core records the best estimate ages of the tephras yield indistinguishable 10be production rate values for spallation with an average value of 4 26 0 21 atoms g 1 a 1 using the lm scaling scheme these values are in best agreement with the most proximal reference 10be production rate from norway

reconstructing the last irish ice sheet 2 a geomorphologically driven model of ice sheet growth retreat and dynamics the ice sheet that once covered ireland has a long history of investigation much prior work focussed on localised evidence based reconstructions and ice marginal dynamics and chronologies with le

a 10be production rate calibration for the arctic we present a baffin bay 10 be production rate calibration derived from glacial deposits in western greenland and baffin island and test our results against published 10 be calibration datasets to develop an arctic 10 be production rate our calibration comprises i 10 be measurements from moraine boulders linked to a 14 c dated moraine at jakobshavn isfjord in western greenland ii an independent and previously published 10 be production rate at jakobshavn isfjord and iii re measured 10 be concentrations from a baffin island calibration site that is included in the north eastern north america dataset combined we calculate a sea level high latitude 10 be production rate for the baffin bay region of 3 96 0 07 atoms g 1 a 1 lal stone scaling model after testing the baffin bay rate against calibration sites in norway and north eastern north america we calculate a more conservative arctic production rate of 3 96 0 15 atoms g 1 a 1 the baffin bay and arctic 10 be production rates are indistinguishable from the north eastern north america 10 be production rate 3 91 0 19 atoms g 1 a 1 and yield overall uncertainties of 2 3 7 1s these production rates reduce systematic uncertainties in 10 be based chronologies of ice margin change and allow 10 be based chronologies to be more confidently compared with high resolution climate records such as those from greenland ice cores copyright 2013 john wiley sons ltd

gypsum formation in non calcareous building sandstone a case study of scrabo sandstone this paper addresses one central issue of building stone research an origin for calcium in gypsum formation in non calcareous sandstones a comparative study of scrabo sandstone from outcrops and a 120 year old building in central belfast shows how weathering has significantly altered the mineralogy preliminary results suggest that the occurrence of gypsum throughout the stone blocks is related to chemical reactions between a pore filling mineral constituent actinolite ca mg amphibole and sulphur oxides from urban pollution these findings advocate an internal source of calcium for gypsum formation and provide new evidence to explain the enhanced decay displayed in some scrabo sandstone copyright 2001 john wiley sons ltd

response of the irish ice sheet to abrupt climate change during the last deglaciation we summarize 121 14c and in situ cosmogenic 10be and 36cl ages that constrain fluctuations of the irish ice sheet iis since the last glacial maximum lgm that can be linked to abrupt climate changes in the north atlantic region these data provide a robust means to date ice sheet fluctuations because similar age events can be identified from widely spaced sites they are constrained by stratigraphy and they can be related to large changes in the configuration of a dynamic ice sheet the following events are recognized 1 ams 14c ages and 10be and 36cl ages as well as offshore data suggest that the last maximum advance of the iis occurred between 27 and 23 cal ka 2 deglaciation began on the western continental shelf and in the irish sea basin at 23 cal ka dated sites from around ireland constrain subsequent widespread retreat of ice sheet margins from the shelf onto irish coastlines during the cooley point interstadial 20 cal ka ams 14c ages suggest that the cooley point interstadial continued until 18 2 cal ka b p during this interstadial retreat of the ice sheet margin into the northern irish sea basin indicates that the iis may have lost up to two thirds of its mass 3 dated sites from northwestern and eastern ireland indicate that the cooley point interstadial was terminated by ice readvance during the clogher head stadial at 18 2 cal ka 4 the linns interstadial was a brief interval 17 0 16 5 cal ka of ice recession following the clogher head stadial that is identified from raised marine sediments in eastern and northern ireland and cosmogenic ages elsewhere in ireland 5 the iis subsequently readvanced during the killard point stadial reaching its maximum extent 16 5 cal ka indicating that the readvance began sometime earlier 6 widespread retreat of the iis began by 15 5 cal ka during the rough island interstadial 6 readvance of cirque glaciers in western ireland occurred during the younger dryas equivalent nahanagan stadial

the use of x ray tomography in the study of water repellents and consolidants abstract to reduce the weathering rate of natural building stones a wide variety of water repellents and consolidants are commercially available although a lot of research is performed on these products it remains difficult to determine which product is appropriate to use for a certain type of building stone each type of building stone has its own petrographic characteristics mineralogy texture leading to typical physical and technical properties which influence its rate of decay the localisation of the products inside a stone type is not only depending on the properties of the products themselves but also linked to the texture and structure of the stone the impregnation depth of the products strongly influences their efficiency and is therefore a key issue in the determination if a product is functional for a certain type of stone x ray micro ct has recently been introduced as a non destructive material evaluation technique for engineering and geology purposes the fact that micro ct can provide information about the internal structure and properties of natural building stones is a major advantage in the study of their conservation firmly linked with more classical research techniques this non destructive technique offers an extra dimension to the cultural heritage research in this paper non destructive x ray computed micro tomography micro ct turns out to be a powerful tool as it can visualise the presence of water repellents and consolidants inside the stone and can help to detect the influence that these treatments exert on porosity and pore size distribution for the visualization of the product its atomic number and density and the amount of product inside the natural building stone is crucial besides the contrast in attenuation the resolution of the micro ct also needs to be taken into account to obtain a good contrast between stone and product by doping with 3 bromopropyltrimethoxysilane more contrast occurs between the stone material and the conservation product when the amount of product inside the samples is very low and the product is homogeneously spread inside the sample the doped product is difficult to distinguish from the stone material due to the resolution of the micro ct when the amount of doped product inside the stone material reaches a certain threshold value the dope will appear in the 2d cross sections derived from micro ct creating a good visualization of the products inside the stone samples

transfer zones of deformation in thrust wedges an experimental study abstract although numerous transfer zones of deformation have been observed in thrust wedges their mechanisms and conditions of development are poorly understood in this paper three basic questions are addressed 1 1 what are the parameters controlling the genesis of transfer zones 2 2 what are the kinematics of thrust propagation during transfer zone development 3 3 which kinds of geological structure link the two compartments on either side of the transfer zone we attempted to solve these problems using a 3 d experimental approach sand models were used to simulate the foreland a rigid but mobile backstop was used to produced a thrust coulomb wedge which was studied during the various stages of its formation shortening led to the development of transfer zones in the wedge separating two domains of homogenous behaviour and connecting thrust planes in different domains the experimental results show that the development of transfer zones is controlled by mechanical and or geometrical parameters such as 1 1 variations in the sedimentary thickness in the foreland 2 2 the steepness of the backstop 3 3 domains with different basal friction in the foreland 4 4 kinked backstop geometry during deformation of the models two types of thrust sequence were identified alternative thrust propagations on both sides of the transfer zone and synchronous thrust propagations which are anastomosed within the transfer zone 3 d reconstructions revealed that the thrust deformations observed in the transfer zone are oblique ramps the frontal thrust bending of the barbados accretionary complex as well as the imbrication of thrust in the castellane arc and the oblique ramp in the zanskar range are discussed in relation to the mechanisms and structures revealed by the models the results of analogue modelling suggest that the development of transfer zones is directly linked to variations in the boundary conditions mechanical and or geometrical between two adjacent parts of a thrust wedge

turbidites and contourites of the palaeogene lefkara formation southern cyprus abstract deposition of the palaeogene to early neogene calcareous and siliceous deep water sediments of the lefkara formation in cyprus was successively dominated by pelagic turbidity current a return to pelagic and then bottom current processes sedimentation occurred on the distal parts of a carbonate slope apron to basin plain setting located in the western arm of the tethys ocean the early phase of sedimentation directly overlying ocean crust ridge derived volcaniclastics and chemogenic sediments was dominated by pelagic deposition of marl marly chalk and radiolarian rich calcilutite this was followed by a gradual increase in the influx of biogenic turbidites forming both chalk and chert deposits from the north during the early and middle eocene period primarily as a response to tectonic uplift of the kyrenia range slower rates of sedimentation returned during the late eocene to early miocene together with significant hiatuses in the sedimentary record together these reflect the cessation of turbidity current input continued pelagic deposition and the onset of bottom current influence on sedimentation a combination of subtle features and supporting evidence allows the recognition of contourites in all the sections studied together with the interaction of turbidity current and bottom current processes in parts of the lefkara formation

physico mechanical properties and durability performance of natural building and decorative carbonate stones from cyprus natural stone was the primary building material in cyprus in the past nowadays its use is mostly confined to decorative purposes and restoration projects this study represents the first thorough and systematic investigation of the characteristics of local carbonate stone the variety of the results recorded highlights the complexity of this natural geomaterial and hence the particular attention needed before selecting the appropriate lithotype in construction practice stones coming from the same geological formation exhibit significant variations in their physico mechanical properties the materials durability against salt crystallization is explained with reference to their pore structure and flexural strength revealing that in many cases small differences may have a significant impact on stone performance the study also investigates the use of novel microdestructive techniques in the prediction of the mechanical properties of the stones under study these techniques can be especially useful in the characterization of monumental stone where sampling is limited or when in situ characterization of stone is required natural stone has been extensively used throughout the history of mankind both for building and decorative purposes even though it is considered one of the most durable traditional geomaterials existing stone structures and monuments often show evidence of weathering and decay stress inflicted during use and by local climate are the major contributing factors to the degradation of building stone the precise response of individual stone samples is highly variable this is attributed to the complex nature and physico mechanical behaviour of natural stone understanding the materials performance under loading or different environmental conditions is therefore considered of crucial importance in ensuring the sustainable use of stone in construction practice

last glacial maximum cirque glaciation in ireland and implications for reconstructions of the irish ice sheet abstract reconstructions of the extent and height of the irish ice sheet iis during the last glacial maximum lgm 19 26 ka are widely debated in large part due to limited age constraints on former ice margins and due to uncertainties in the origin of the trimlines a key area is southwestern ireland where various lgm reconstructions range from complete coverage by a contiguous iis that extends to the continental shelf edge to a separate more restricted southern sourced kerry cork ice cap kcic we present new 10be surface exposure ages from two moraines in a cirque basin in the macgillycuddy s reeks that provide a unique and unequivocal constraint on ice thickness for this region nine 10be ages from an outer moraine yield a mean age of 24 5 1 4 ka while six ages from an inner moraine yield a mean age of 20 4 1 2 ka these ages show that the northern flanks of the macgillycuddy s reeks were not covered by the iis or a kcic since at least 24 5 1 4 ka if there was more extensive ice coverage over the macgillycuddy s reeks during the lgm it occurred prior to our oldest ages

century to millennial scale sedimentological geochemical records of glacial holocene sediment variations from the barra fan ne atlantic the barra fan located at the continental margin of nw scotland offers a unique possibility to retrieve records of exceptional high resolution to obtain climate records on a century millennial timescale we used a sedimentological geochemical approach to examine the sediment variations that reflect the palaeoceanography and climate history of the area inorganic chemistry combined with micropalaeontology reveals trends and changes in ne atlantic palaeoceanography and northwest european climate at the sub milankovitch frequency this study builds on results from two british geological survey cores and one giant piston core core 57 11 59 core 56 10 36 and images core md95 2006 that were obtained during the neapacc ne atlantic palaeoceanography special topic nerc phase geochemical records of lithogenic input fluctuate rapidly and their patterns parallel sea surface temperature and particle size records the cold periods are characterized by increased clay input compared to the warm periods the younger dryas period and other prominent periods such as the equivalent of heinrich event 1 show extremely expanded sections up to several metres in thickness enhancement of accumulation rates in the glacial section is due to the influence of downslope sedimentation meltwater deposition and large scale currents redistributing the sediment along the upper slope the radiochemical tracer excess 230 th shows that major shifts in terrigenous sediment supply were extremely rapid over the last 15 ka the shifts in terrigenous supply occurred over time spans of less than a century century scale events of lithogenic input can be visually correlated to other north atlantic climate records such as the gisp2 greenland ice core 18 o record for the last 15 ka although the resolution of radiocarbon dating of these events in the sediments is not sufficiently precise to verify that the visual correlations are correct the particle flux and biogenic records show sawtooth shaped cycles opposite to the dansgaard oeschger cycles

monitoring of weathering and conservation of building materials through non destructive x ray computed microtomography x ray computed microtomography ct is a promising non destructive imaging technique based on measurements of the attenuation of x rays it provides information on the internal structure of small samples with a maximum resolution of 10 m for this study two porous local natural building stones the sandstone of bray and the limestone of maastricht were selected possible applications of the ct technique for qualitative monitoring of changes comprise 1 to non destructively determine porosity based on 3 d images 2 to visualise weathering phenomena at the micron scale 3 to understand the rationale of weathering processes 4 to visualise the presence of water repellents and consolidation products 5 to monitor their protective effects during decay in order to understand the operating mechanisms and 6 to provide advise on the suitability of products for the treatment of a particular rock type the ct technique proves to be a powerful monitoring tool for the future as the combination of 3 d visualisation and 3 d data provide new insights that could optimise conservation and restoration techniques of building materials

pleistocene glacial history of the nw european continental margin abstract in this paper new and previously published data on the pleistocene glacial impact on the nw european margin from ireland to svalbard between c 48 n 80 n are compiled the morphology of the glaciated part of the european margin strongly reflects repeated occurrence of fast moving ice streams creating numerous glacial troughs channels that are separated by shallow bank areas end moraines have been identified at several locations on the shelf suggesting shelf edge glaciation along the major part of the margin during the last glacial maximum deposition of stacked units of glacigenic debris flows on the continental slope form fans at a number of locations from 55 n and northwards whereas the margin to the south of this is characterised by the presence of submarine canyons glaciation curves based primarily on information from the glacial fed fan systems that depict the pleistocene trends in extent of glaciations along the margin have been compiled these curves suggest that extensive shelf glaciations started around svalbard at 1 6 1 3 ma while repeated periods of shelf edge glaciations on the uk margin started with mis 12 c 0 45 ma the available evidence for mis 2 suggest that shelf edge glaciation for the whole margin was reached between c 28 and 22 14 c ka bp and maximum positions after this were more limited in some regions north sea and lofoten the last glacial advance on the margin has been dated to 15 13 5 14 c ka bp and by c 13 14 c ka bp the shelf areas were completely deglaciated the younger dryas loch lomond advance reached the coastal areas in only a few regions

the dynamics of mountain erosion cirque growth slows as landscapes age glacial cirques are widely used palaeoenvironmental indicators and are key to understanding the role of glaciers in shaping mountain topography however notable uncertainty persists regarding the rate and timing of cirque erosion in order to address this uncertainty we analyse the dimensions of 2208 cirques in britain and ireland and model ice accumulation to investigate the degree of coupling between glacier occupation times and cirque growth results indicate that during the last 120 ka cirques were glacier free for an average of 52 0 21 2 ka 43 18 occupied by small largely cirque confined glaciers for 16 2 9 9 ka 14 8 and occupied by large glaciers including ice sheets for 51 8 18 6 ka 43 16 over the entire quaternary i e 2 6 ma we estimate that cirques were glacier free for 1 1 0 5 ma occupied by small glaciers for 0 3 0 2 ma and occupied by large glaciers for 1 1 0 4 ma comparing occupation times to cirque depths and calculating required erosion rates reveals that continuous cirque growth during glacier occupation is unlikely instead we propose that cirques attained much of their size during the first occupation of a non glacially sculpted landscape perhaps during the timeframe of a single glacial cycle during subsequent glacier occupations cirque growth may have slowed considerably with the highest rates of subglacial erosion focused during periods of marginal small glacier glaciation we propose comparatively slow rates of growth following initial cirque development because a least resistance shape is formed and as cirques deepen sediment becomes trapped subglacially partly protecting the bedrock from subsequent erosion in support of the idea of rapid cirque growth we present evidence from northern british columbia where cirques of comparable size to those in britain and ireland developed in less than 140 ka

periglacial trimlines and the extent of the kerry cork ice cap sw ireland abstract periglacial trimlines on the mountains of sw ireland demarcate a contrast between glacially scoured bedrock on lower ground and thick periglacial regolith covers on summits and plateaus and have previously been interpreted as marking the maximum altitude of the kerry cork ice cap kcic glacially eroded bedrock extends to the highest points on the beara peninsula but the highest summits on the iveragh peninsula support thick regolith covers trimline altitudes on the iveragh peninsula decline radially from a former ice divide near the head of kenmare river from 700 m altitude near the divide to 470 m near dingle bay contrasts in the clay mineral content of above and below trimline soils and cosmogenic isotope exposure ages indicate a lgm age for the trimlines assumption that the trimlines represent the maximum thickness of the kcic implies an ice divide altitude of 825 m however modelling of ice surface profiles demonstrates that an ice divide at 825 m is irreconcilable with stratigraphic evidence for extension of the kcic at least as far as garryvoe 115 km east of the divide we infer that the iveragh trimlines represent a former englacial transition between warm based sliding ice on low ground and cold based ice on high ground rather than delimiting nunataks as previously interpreted modelling of ice surface altitudes suggests that during the lgm the kcic probably overtopped all of the mountains in sw ireland the trimlines of sw ireland thus define the minimum rather than maximum altitude of the kcic at the lgm as well as the sites of former cold patches within the kcic

the last glacial maximum at 44 s documented by a 10be moraine chronology at lake ohau southern alps of new zealand abstract determining whether glaciers registered the classic last glacial maximum lgm 26 500 19 000 yrs ago coevally between the hemispheres can help to discriminate among hypothesized drivers of ice age climate here we present a record of glacier behavior from the southern alps of new zealand during the local lgm llgm we used 10 be surface exposure dating methods and detailed glacial geomorphologic mapping to produce a robust chronology of well preserved terminal moraines deposited during the llgm near lake ohau on central south island we then used a glaciological model to estimate a llgm glacier snowline and atmospheric temperature from the ohau glacier record seventy three 10 be surface exposure ages place culminations of terminal moraine construction and hence completions of glacier advances to positions outboard of present day lake ohau at 138 600 10 600 yrs 32 520 970 yrs ago 27 400 1300 yrs ago 22 510 660 yrs ago and 18 220 500 yrs ago recessional moraines document glacier recession into the lake ohau trough by 17 690 350 yrs ago exposure of an ice molded bedrock bench located inboard of the innermost llgm moraines by 17 380 510 yrs ago indicates that the ice tongue had receded about 40 of its overall length by that time comparing our chronology with distances of retreat suggests that the ohau glacier terminus receded at a mean net rate of about 77 m yr 1 and its surface lowered by 200 m between 17 690 and 17 380 yrs ago a long term continuation of ice retreat in the ohau glacier catchment is implied by moraine records at the head of irishman stream valley a tributary of the ohau glacier valley the irishman stream cirque glacier advanced to produce a set of lateglacial moraines at 13 000 500 yrs ago implying that the cirque glacier was less extensive prior to that advance we employed a glaciological model fit to these mapped and dated llgm moraines to derive snowline elevations and temperature parameters from the ohau glacier record the modeling experiments indicate that a snowline lowering of 920 50 m and temperature depression of 6 25 0 5 c below modern values allows for the ohau glacier to grow to an equilibrium position within the lgm moraine belt taken together with a glaciological simulation reported from the irishman stream valley snowlines and temperatures increased by at least 520 m and 3 6 c respectively between 18 000 and 13 000 yrs ago climate parameters derived from the ohau glacier reconstruction are similar to those derived from glacier records from patagonia to air temperature indicators from antarctica as well as to sea surface temperature and stratification signatures of the southern ocean we think that the best explanation for the observed southern llgm is that southern winter duration modulated southern ocean sea ice which in turn influenced southern ocean stratification and made the surface ocean cooler orbitally induced cooling of the southern ocean provides an explanation for the llgm in the southern alps having been coincident with the northern lgm we argue further that the global effect of north atlantic stadials led to disturbance of southern ocean stratification southward shifts of the subtropical front and retreat of southern alps glaciers collapse of southern ocean stratification during heinrich stadial 1 along with attendant sea surface warming triggered the onset of the last glacial termination in the southern alps of new zealand

quaternary deposits and glacial stratigraphy in ireland quaternary stratigraphic studies in ireland have been based largely on lithostratigraphy the division of complex sedimentary sequences into the traditional framework of munsterian and midlandian events has created a series of stratigraphic scenarios which cannot be fully substantiated either by biostratigraphy or by facies basin analysis many of the current problems of glacial stratigraphy in ireland therefore arise directly from the field procedures used and the frameworks used to subdivide sedimentary sequences these problems are centred on the selection of type sites the subdivision of sedimentary sequences into unnatural divisions the concepts of direct and indirect stratigraphy classical models of climatically determined ice advance retreat cycles and the genetic inferences of the term till the conceptual basis of various stratigraphic schemes has changed little since the work of farrington 1934 1966 it is argued that a more realistic approach to description and assessment of glacigenic sediments should be based on basinal facies analysis and must include a documentation of the composition and geometry of three dimensional facies variations palaeoenvironmental interpretations of complex glacigenic sequences especially in coastal locations should take account of the influences of marine ice sheets on the sedimentary record in the past most sequences were interpreted in terms of glacioterrestrial models a large body of sedimentary evidence now indicates that shallow glaciomarine environments occurred along the margins of the last ice sheet during its maximum and subsequent retreat phases the locations and patterns of associated icemarginal systems indicate that the magnitude of and patterns of crustal deformation were greater and more complex than formerly realised thus the primary control on sea level variation at successive ice sheet margins was largely a function of glacioisostatic disequilibrium although complex glacial and glacially related sequences are known it is argued here that most of the multiple glacigenic sequences in ireland can be accommodated within the midlandian cold stage the basal units from certain sequences and erratic fans have been attributed to events earlier than the midlandian however it is difficult to compare these traces of earlier events from different sectors of the island due to poor dating correlation and the fact that direct and indirect stratigraphy is not adequately defined or separated the age of the gortian style interglacial sequences the implications of their floristic composition and their relationships to drift stratigraphy remains a major problem in stratigraphic constructions of the irish quaternary the stratigraphic significance of many till units must remain largely unknown until these matters are resolved at present it is not clear if the gortian sequences represent more than one interglacial a series of exposures in ulster provide evidence for major environmental changes during the midlandian cold stage these include an early stadial an early forest biozone 48 1 ka bp an early herb biozone 41 5 ka bp a middle interstadial phase of cold but non glacial aspect 30 5 ka bp a late stadial max 24 22 ka bp and a late glacial climatic oscillation the late midlandian stadial comprises a major glaciation that almost covered the island and a later more restricted phase when drumlins formed in the northern and western parts of the island max 17 ka bp

stress tensor analysis in the taiwan area from focal mechanisms of earthquakes abstract we produce a map of the stress pattern in and around taiwan based on 200 earthquake focal mechanism solutions these solutions were determined by using data from taiwan telemetered seismographic network microearthquake surveys and wwssn the stresses are derived through a minimization of angles between the slip vector and the shear stress on each nodal plane considered as a fault employing appropriate weighting factors the whole set of focal mechanisms is divided into several groups mainly according to apparent clustering of the event locations the results show that the direction of maximum principal stress in taiwan area is nearly horizontal and se nw on average this is in good agreement with the direction of relative motion between the philippine sea plate and the eurasian plate in western taiwan the fan shaped distribution of the maximum principal stress is consistent with the direction of philippine sea eurasian plate convergence through a simple model of viscous material indented by a rigid wedge in the northeastern part of taiwan a nearly horizontal minimum principal stress oriented n s is found for shallow depths it occurs in a region of low seismic velocities probably related to the back arc activity of the okinawa trough down dip compressional and down dip extensional stresses have been identified in different depth ranges within the subducting slab of the philippine sea plate in the northern taiwan this may reflect the slab characteristics in this area a complex stress pattern prevails in the hualien area at the junction between the ryukyu subduction system and the taiwan collision zone

physical and mechanical properties of the repaired sandstone ashlars in the facing masonry of the charles bridge in prague czech republic and an analytical study for the causes of its rapid decay the facing masonry of the gothic charles bridge in prague czech republic has been largely altered during nineteenth and twentieth century repairs due to extensive replacements of weathered sandstone ashlar blocks natural stone varieties used during these replacements show different responses to a variety of weathering processes which lead to their rapid decay the decay of the newer stone has been accelerated by use of portland cement paste as the binding and fill material instead of the original hydraulic lime based and cocciopesto type mortars the hardened portland cement paste makes an almost impermeable barrier with permeability three to four orders of magnitude lower compared to the original mortars and natural stone the low permeability of this new alien material results in the accumulation of water soluble salts specifically nitrates but also sulphates and chlorides in the facing masonry ashlars with their crystallisation coming in the form of both sub and efflorescence as well as the development of various decay forms blistering granular disintegration and or scaling and flaking the source of the water soluble salts can be traced back to previous restoration attempts these included chemical cleaning black crust removal by nitric acid ammonium hydroxide ammonium water or ammonium hydrogen carbonate all which can be linked to high nitrate content in the efflorescence

geomorphic evidence for tear faults accommodating lateral propagation of an active fault bend fold wheeler ridge california abstract wheeler ridge is the topographic expression of an actively growing fault bend fold developed in the hanging walls of a system of mostly north vergent blind thrusts the eastern tip of the fold system has migrated laterally by approximately 3 km during the last 120 ka perpendicular to the regional shortening direction comparison of surface topography and structural cross sections indicates that eastern wheeler ridge comprises three fold segments whose topographic expression steps southward towards the eastern end of the structure lateral propagation of the fold is associated with numerous tear faults expressed as fault scarps that face towards the eastern end of the fold we suggest that these tear faults accommodate earthquake related processes that collectively build plunge of the fold and lateral propagation on blind thrusts we envisage that the fold will grow primarily by thrust faulting events with similar displacement s along strike that are terminated abruptly at tear faults build displacement over multiple earthquake cycles and then step eastward to form a new tear fault formation of especially large tear faults is inferred to be in response to an increase in rock strength governed by lithology the high fault displacement vs length d l for wheeler ridge may be related to high strain rates across a restraining bend in the nearby san andreas strike slip fault system

glaciation and sea level change for ireland and the irish sea since late devensian midlandian time the sea level change around the coast of ireland and the irish sea for the past 20 000 years is primarily the combined result of the glacio isostatic adjustment of the crust to the removal of ice over the british isles and the total eustatic change from the global ice sheets however the isostatic effects due to the removal of ice from northern europe and north america and the addition of meltwater into the oceans also make a significant contribution predictions of sea level change based on glacio hydro isostatic models are compared with observations to constrain the ice volume over ireland at the time of the last glacial maximum and the maximum ice height appears to have been of the order of 600 m the models predict well the spatial variability in sea level change observed across the region for holocene and lateglacial time with levels above present being predicted only for northeastern ireland and north of about morecambe bay the models do not support suggestions that lateglacial levels along the east coast of ireland or the coast of wales were 50 150 m above their present levels consistent models that would produce such large lateglacial highstands are incompatible with all other sea level and glacial evidence for the british isles palaeobathymetry and palaeoshoreline reconstructions for the irish sea indicates that a tenuous landbridge between britain and ireland developed only across the celtic sea between about 18000 and 14000 years bp

space geodesy constrains ice age terminal deglaciation the global ice 6g_c vm5a model a new model of the last deglaciation event of the late quaternary ice age is here described and denoted as ice 6g c vm5a it differs from previously published models in this sequence in that it has been explicitly refined by applying all of the available global positioning system gps measurements of vertical motion of the crust that may be brought to bear to constrain the thickness of local ice cover as well as the timing of its removal additional space geodetic constraints have also been applied to specify the reference frame within which the gps data are described the focus of the paper is upon the three main regions of last glacial maximum ice cover namely north america northwestern europe eurasia and antarctica although greenland and the british isles will also be included if peripherally in the discussion in each of the three major regions the model predictions of the time rate of change of the gravitational field are also compared to that being measured by the gravity recovery and climate experiment satellites as an independent means of verifying the improvement of the model achieved by applying the gps constraints several aspects of the global characteristics of this new model are also discussed including the nature of relative sea level history predictions at far field locations in particular the caribbean island of barbados from which especially high quality records of postglacial sea level change are available but which records were not employed in the development of the model although ice 6g c vm5a is a significant improvement insofar as the most recently available gps observations are concerned comparison of model predictions with such far field relative sea level histories enables us to identify a series of additional improvements that should follow from a further stage of model iteration

a synthesis of the geologic evolution of taiwan abstract the island arc of taiwan is composed of cenozoic geosynclinal sediments more than 10 000 m thick lying on a pre tertiary metamorphic basement pleistocene to miocene andesitic islands surround the main island and are related mostly to arc magmatism the penghu island group in the taiwan strait is covered with pleistocene flood basalt neogene shallow marine clastic sediments are exposed mainly in the western foothills with pleistocene andesitic extrusives at the northern tip and the northeastern offshore islands a thick sequence of paleogene to miocene argillitic to slaty metaclastic rocks underlies the western central range and forms the immediate sedimentary cover on the pre tertiary metamorphic complex to the east which represents an older mesozoic arc trench system the coastal range in eastern taiwan is a neogene andesitic magmatic arc including also a large variety of volcaniclastic and turbiditic sediments cenozoic taiwan is the site of arc continent collision where the luzon arc on the philippine sea plate overrides the chinese continental margin on the eurasian plate east and northeast of taiwan the polarity of subduction changes whereby the oceanic philippine sea plate is subducting beneath the ryukyu arc system on the eurasian plate continent arc collision in taiwan island is anomalous and may occur in a broad belt of deformation rather than along a well defined plate boundary or subduction zone

late pleistocene mountain glacier response to north atlantic climate change in southwest ireland stephan harrison neil glasser ed anderson susan ivy ochs peter w kubik 2010 late pleistocene mountain glacier response to north atlantic climate change in southwest ireland quaternary science reviews 29 27 28 3948 3955

reconstruction of changes in the weddell sea sector of the antarctic ice sheet since the last glacial maximum the weddell sea sector is one of the main formation sites for antarctic bottom water and an outlet for about one fifth of antarctica s continental ice volume over the last few decades studies on glacial geological records in this sector have provided conflicting reconstructions of changes in ice sheet extent and ice sheet thickness since the last glacial maximum lgm at ca 23 19 calibrated kiloyears before present cal ka bp terrestrial geomorphological records and exposure ages obtained from rocks in the hinterland of the weddell sea ice sheet thickness constraints from ice cores and some radiocarbon dates on offshore sediments were interpreted to indicate no significant ice thickening and locally restricted grounding line advance at the lgm other marine geological and geophysical studies concluded that subglacial bedforms mapped on the weddell sea continental shelf subglacial deposits and sediments over compacted by overriding ice recovered in cores and the few available radiocarbon ages from marine sediments are consistent with major ice sheet advance at the lgm reflecting the geological interpretations different ice sheet models have reconstructed conflicting lgm ice sheet configurations for the weddell sea sector consequently the estimated contributions of ice sheet build up in the weddell sea sector to the lgm sea level low stand of 130 m vary considerably in this paper we summarise and review the geological records of past ice sheet margins and past ice sheet elevations in the weddell sea sector we compile marine and terrestrial chronological data constraining former ice sheet size thereby highlighting different levels of certainty and present two alternative scenarios of the lgm ice sheet configuration including time slice reconstructions for post lgm grounding line retreat moreover we discuss consistencies and possible reasons for inconsistencies between the various reconstructions and propose objectives for future research the aim of our study is to provide two alternative interpretations of glacial geological datasets on antarctic ice sheet history for the weddell sea sector which can be utilised to test and improve numerical ice sheet models

climate sensitivity and geomorphological response of cirque glaciers from the late glacial to the holocene sierra nevada spain abstract through a detailed geomorphological study including thourough mapping of the geomorphic features as well as 10be cosmic ray exposure cre dating the geomorphological evolution of the mulhacen cirque since the maximum ice extent of the last glacial cycle until nowadays was determined this glacial cirque is shaped on the northern face of the mulhacen peak 3479 m a s l 37 03 12 n 3 18 41 w sierra nevada southern spain it includes several depositional and erosional glacial landforms that allowed reconstructing its environmental evolution since the last glacial cycle furthermore the sequence of glacial oscillations from this site was compared to that of other cirques of the massif evidencing that i new glaciers formed in these cirques during the younger dryas yd and ii disappeared at 11 7 1 0 ka depending on the altitude orientation and height of the cirque walls the final deglaciation of the cirques generated a diversity of landscapes including a wide range of glacial and periglacial landforms such as polished surfaces sequences of moraines proto rock glaciers or large rock glacier systems no glaciers existed in the sierra nevada during the middle holocene only the cirques whose summits exceed 3300 m are north exposed and whose walls exceed 300 m high i e mulhacen and veleta hosted glaciers during neoglacial phases including the little ice age lia approx 1300 1850 ce during these periods climate oscillations favoured the formation of small glaciers in these cirques which generated large moraine systems with either one polygenic ridge or a sequence of spaced frontal arcs the existence of glaciers impeded the formation of permafrost related landforms such as rock glaciers and protalus lobes until the end of the lia when they started to form these results are compared with the deglacial evolution in 55 cirques from iberian mountains as well as from glacial cirques from other mid latitude mountains and subpolar regions the chronology of their deglaciation as well as the landforms generated during glacial retreat followed similar patterns with no significant differences at regional scale for each mountain range the geomorphological diversity existing in each cirque depends on the local topographic characteristics although they formed during the same climatic phases

timing of glacial retreat in the wicklow mountains ireland conditioned by glacier size and topography this paper presents 170 schmidt hammer exposure ages from moraine boulders and glacially sculpted bedrock to reveal the post last glacial maximum lgm history of the wicklow mountains ireland these data suggest that large ice masses survived for 4 7 ka after retreat of the irish sea ice stream and were sustained by summit ice fields until 16 6 ka post lgm retreat was dynamic with re advance moraines deposited in response to heinrich stadial 1 however these events reflect short term ice front oscillations 1 ka during the long term retreat phase retreat from re advance positions was synchronous across the range and paced by climate with time progressive deglaciation from low to high elevation in contrast marked asynchroneity in the timing of younger dryas deglaciation is closely linked to snow redistribution and indicates that for small cirque glaciers 1 km2 topography can exert the primary control on glacier survival this result has important implications for palaeoclimate econstructions as cirque glacier dynamics may be unrelated to climate this is further complicated by post depositional processes which can result in moraine ages e g 10be which post date retreat future palaeoclimate studies should prioritise cirque glaciers where snow contributing areas are small and where postdepositional disturbance is limited matrix poor boulder rich moraines

radiocarbon dating of irish sea sediments abstract radiocarbon dating has been carried out on three cores from areas of muddy sediments in the n irish sea to estimate rates of sediment accumulation 14c age profiles of the two eastern basin cores revealed a near constant age from the sediment surface to the base of the core 12 500 1000 years bp the 14c age profile of the western basin core revealed a zone of apparent mixing to a depth of 55 cm underlain by a zone of constant sedimentation rate 0 018 cm y 1 to 160 cm these data are discussed in relation both to previously reported sedimentological studies of the area and to the authorised discharges of low level radioactive waste from the sellafield nuclear fuel reprocessing plant

chronology of glaciations in the sierra nevada california from 10be surface exposure dating abstract we use 10 be surface exposure dating to construct a high resolution chronology of glacial fluctuations in the sierra nevada california most previous studies focused on individual glaciated valleys whereas our study compares chronologies developed throughout the range to identify regional patterns in the timing of glacier response to major climate changes sites throughout the range indicate last glacial maximum retreat at 18 8 1 9 ka 2 that suggests rather consistent changes in atmospheric variables e g temperature and precipitation throughout the range the penultimate glacial retreat occurred at ca 145 ka our data suggest that the sierra nevada landscape is dominated by glacial features deposited during marine isotope stage mis 2 and mis 6 deposits of previously recognized glaciations between circa 25 and 140 ka e g mis 4 tenaya early tahoe cannot be unequivocally identified the timing of sierra nevada glacial retreat correlates well with other regional paleoclimate proxies in the sierra nevada but differs significantly from paleoclimate proxies in other regions our dating results indicate that the onset of lgm retreat occurred several thousand years earlier in the sierra nevada than some glacial records in the western us

the role of saline solution properties on porous limestone salt weathering by magnesium and sodium sulfates saline solution properties viscosity in particular are shown to be critical in salt weathering associated with sodium and magnesium sulfate crystallization in porous limestone the crystallization of sodium and magnesium sulfate within a porous limestone has been studied at a macro and microscale using different techniques including mercury intrusion porosimetry environmental scanning microscopy and x ray computed tomography such analysis enabled the visualization of the crystallization process in situ and at high magnification yielding critical information as to where and how salts crystallize sodium sulfate decahydrate mirabilite tends to crystallize in large pores as euhedral micron sized crystals formed at low supersaturation near to the surface of the stone in contrast magnesium sulfate heptahydrate epsomite tends to precipitate as anhedral wax like aggregates formed at high supersaturation and distributed homogeneously throughout the stone pore system filling large and small pores while the former crystallization behavior resulted in scale formation the latter led to crack development throughout the bulk stone ultimately the contrasting weathering behavior of the two sulfates is explained by considering differences in flow dynamics of solutions within porous materials that are mainly connected with the higher viscosity of magnesium sulfate saturated solution 7 27 cp when compared with sodium sulfate saturated solution 1 83 cp on the basis of such results new ways to tackle salt weathering particularly in the field of cultural heritage conservation are discussed

adjustments by the charwell river new zealand to uplift and climatic changes major climatic changes and rapid local and regional tectonic movements were common in new zealand during the late quaternary and caused a diversity of adjustments in the drainage basin and piedmont reaches of the charwell river which are separated by the hope fault the onset of semi arid frigid climates during the latest pleistocene probably greatly increased hillslope sediment yields in a periglacial environment and the piedmont reach aggraded as much as 42 m on top of a broad strath with the return of humid mesic climates in the holocene sediment yields decreased as dense forests again mantled the slopes and the piedmont reach degraded as mush as 81 m dating of eleven cut and strath terraces by radiocarbon calibrated weathering rind measurements on greyawake cobbles shows the degradation rates varied greatly during the last 14 ka 1 ka 1000 yr initial degradation rates of 4 m ka 1 increased to 30 m ka 1 by 6 ka ago during a mid holocene climatic optimum since 4 ka ago degradation rates have been only 1 2 m ka 1 comparable to uplift rates in the piedmont reach inferred from marine terrace studies and the river is again cutting a broad strath each broad strath represents equilibrium conditions attained by this powerful stream during interglacial times despite episodes of being overwhelmed by climatically induced sediment yield increases during full glacial climates and having to maintain a long term degradation rate equal to the uplift rate the 75 81 m of degradation since formation of the latest pleistocene fill terrace tread is the sum of the amount of late pleistocene valley floor aggradation and the amount of regional uplift that occurred between the estimated times of major strath formation at about 30 and 0 ka the 39 m of tectonically induced degradation below the pre aggradation strath is sufficiently large that post 30 ka uplift may have doubled holocene degradation rates each of the eleven degradation terraces represents pauses of a few centuries in holocene downcutting brief equilibrium conditions were attained by streambed armoring and concurrent growth of riparian plants both processes progressively increased hydraulic roughness and the shear stresses needed to entrain streambed materials occasional floods possibly from rare cyclones derived from tropical moisture sources destroyed streambed armor and channel downcutting was renewed thus the formation of eleven equilibrium terraces can be accounted for without postulating additional tectonic perturbations or secular climatic changes

deglacial history of the west antarctic ice sheet in the weddell sea embayment constraints on past ice volume change the retreat history of the west antarctic ice sheet wais since the last glacial maximum is important for understanding the process of rapid deglaciation constraining models that seek to predict the future trajectory of the ice sheet and for estimating rates of sea level change here we report new glacial geologic data from the southwestern weddell sea embayment that demonstrate that this part of the wais was thinner than previously suggested and that there was progressive thinning of the ice sheet by 230 480 m since ca 15 ka we use geomorphological data and a numerical ice sheet model to reconstruct the ice sheet in the weddell sea at the last glacial maximum the volume of this ice would have added between 1 4 and 2 0 m to postglacial sea level rise and would not have been sufficient to contribute significantly to meltwater pulse 1a a rapid rise in sea level 14 200 yr ago

micro destructive mapping of the salt crystallization front in limestone salt crystallization is widely recognized as one of the most damaging factors affecting stone monuments and buildings conservation of structures suffering from weathering due to salt crystallization can be immensely expensive and time consuming the assessment of salt laden buildings alone is often challenging and costly in its own right in this paper the drilling resistance measurement system drms and the scratch tool are evaluated for their ability to map salt crystallization in natural building stone the laboratory results indicate that the two aforementioned micro destructive techniques are indeed capable of detecting the location of the salt crystallization front in limestone impregnated with sodium sulfate this is facilitated due to the increased resistances recorded during drilling and scratching in areas where pore clogging due to salt crystallization exists the drms was further successfully employed in situ on masonry exhibiting the effects of salt decay the successful application of both micro destructive techniques in the laboratory and of the drms alone in situ suggests that these may potentially be used to detect subflorescence before it becomes damaging

postglacial relative sea level observations from ireland and their role in glacial rebound modelling the british isles have been the focus of a number of recent modelling studies owing to the existence of a high quality sea level dataset for this region and the suitability of these data for constraining shallow earth viscosity structure local to regional ice sheet histories and the magnitude timing of global meltwater signals until recently the paucity of both glaciological and relative sea level rsl data from ireland has meant that the majority of these glacial isostatic adjustment gia modelling studies of the british isles region have tended to concentrate on reconstructing ice cover over britain however the recent development of a sea level database for ireland along with emergence of new glaciological data on the spatial extent thickness and deglacial chronology of the irish ice sheet means it is now possible to revisit this region of the british isles here we employ these new data to constrain the evolution of the irish ice sheet we find that in order to reconcile differences between model predictions and rsl evidence a thick spatially extensive ice sheet of 600 700 m over much of north and central ireland is required at the lgm with very rapid deglaciation after 21 k cal yr bp copyright 2007 john wiley sons ltd

x ray computed tomography study of the influence of consolidants on the hydric properties of sandstones for stone conservation studies abstract x ray computed tomography x ray ct has been used to study the petrophysical characteristics of a jurassic sandstone from asturias northern spain used as building stone in several monuments in the region ct monitoring of water capillarity tests has made it possible to visualize the movement of water inside the samples to relate this movement with texture characteristics and to measure the height reached in successive images thereby determining the capillary penetration coefficient based on this coefficient the effective capillary pore radius has also been estimated an advantage of the use of ct is that as the information comes from the sample interior border effects that can be generated in the external faces can be avoided the ct was also used to visualize how a commercial organosilicon consolidant penetrates inside the rock by means of capillarity a usual way of consolidant application in stone restoration processes the coefficient of capillary penetration of the product determined on the basis of the measurements made on the tomographic images is 53 less than that of water the influence of rock texture characteristics on the capillarity both of the consolidant and the water was also observed the samples underwent ct water capillarity studies before and after the consolidant application proving that the treatment improves the rock s hydric properties the coefficient of capillary penetration decreased by 24 following the application of the consolidant whereas the effective pore radius decreased by more than 40

simulated influences of lake agassiz on the climate of central north america 11 000 years ago eleven thousand years ago large lakes existed in central and eastern north america along the margin of the laurentide ice sheet the large scale north american climate at this time has been simulated with atmospheric general circulation models1 2 but these relatively coarse global models do not resolve potentially important features of the mesoscale circulation that arise from interactions among the atmosphere ice sheet and proglacial lakes here we present simulations of the climate of central and eastern north america 11 000 years ago with a high resolution regional climate model nested within a general circulation model the simulated climate is in general agreement with that inferred from palaeoecological evidence our experiments indicate that through mesoscale atmospheric feedbacks the annual delivery of moisture to the laurentide ice sheet was diminished at times of a large cold lake agassiz relative to periods of lower lake stands the resulting changes in the mass balance of the ice sheet may have contributed to fluctuations of the ice margin thus affecting the routing of fresh water to the north atlantic ocean a retreating ice margin during periods of high lake level may have opened an outlet for discharge of lake agassiz into the north atlantic a subsequent advance of the ice margin due to greater moisture delivery associated with a low lake level could have dammed the outlet thereby reducing discharge to the north atlantic these variations may have been decisive in causing the younger dryas cold event3 4

interhemispheric ice sheet synchronicity during the last glacial maximum the timing of the last maximum extent of the antarctic ice sheets relative to those in the northern hemisphere remains poorly understood we develop a chronology for the weddell sea sector of the east antarctic ice sheet that combined with ages from other antarctic ice sheet sectors indicates that the advance to and retreat from their maximum extent was within dating uncertainties synchronous with most sectors of northern hemisphere ice sheets surface climate forcing of antarctic mass balance would probably cause an opposite response whereby a warming climate would increase accumulation but not surface melting our new data support teleconnections involving sea level forcing from northern hemisphere ice sheets and changes in north atlantic deep water formation and attendant heat flux to antarctic grounding lines to synchronize the hemispheric ice sheets

pattern and timing of retreat of the last british irish ice sheet during the last glacial the ice sheet that subsumed most of britain ireland and the north sea attained its maximum extent by 27 ka bp and with an ice volume sufficient to raise global sea level by ca 2 5 m when it melted we reconstruct the demise of this british irish ice sheet biis and present palaeo glaciological maps of retreat stages between 27 and 15 ka bp the whole land area was investigated using remote sensing data and we present maps of moraines meltwater channels eskers and drumlins and a methodology of how to interpret and bring them together for the continental shelf numerous large moraines were discovered recording an extensive pattern of retreat stretching from sw ireland to the shetland isles from an integration of this new mapping of glacial geomorphology 26 000 landforms with previously published evidence compiled in the britice database we derive a pattern of retreat for the whole biis we review and compile relevant dates 881 examples that constrain the timing of retreat all data are held within a geographic information system gis and are deciphered to produce a best estimate of the combined pattern and timing of retreat pattern information reveals an ice sheet mainly comprised of a shelf parallel configuration from sw ireland to ne scotland but it spread far enough to the south to incorporate outlying ice domes over wales the lake district and kerry final disintegration was into a number of separate ice caps rather than reduction as a single mass and paradoxically retreat was not always back to high ground by 23 ka bp ice withdrew along its northern boundaries at the same time as the southern margins were expanding including transient ice streaming down the irish sea and advances of lobes in the cheshire basin vale of york and east coast of england ice divides migrated south by 19 ka the ice sheet was in crisis with widespread marine based ice losses particularly in the northern north sea and the irish sea considerable dynamic thinning occurred during this phase final collapse of all marine sectors occurred by 17 ka bp and with most margins beginning to back step onshore disintegration of the north sea ice bridge between britain and norway remains loosely constrained in time but the possibility of catastrophic collapse of this sector is highlighted the north channel and irish sea ice streams had finally cleaved the ice sheet into separate irish and scottish ice sheets by 16 ka bp rates of ice loss were found to vary widely over space and time e g 65 260 km3 per year the role of ice streams and calving losses of marine based sectors are examined retreat rates of up to ca 150 ma 1 were found for some ice stream margins that large parts 2 3 of the biis were marine based drained by ice streams and possibly with fringing ice shelves in places makes it a useful analogue for the west antarctic ice sheet wais this is especially so because the biis deglaciated in response to rising temperatures and a rising sea level driven by melting of other ice masses which are the current forcings that might cause collapse of the wais our reconstruction when viewed from the opposite perspective documents when fresh land became exposed for exploitation by plants animals and man and records for how long such land has been available for soil and geochemical development and ecological succession

reply to comment received from j c knight regarding last glacial maximum cirque glaciation in ireland and implications for reconstructions of the irish ice sheet by barth et al 2016 quaternary science reviews 141 85 93

sandstone weathering in tropical climate results of low destructive investigations at the temple of angkor wat cambodia abstract investigations at the temple of angkor wat aimed at the explanation of the major weathering processes of building sandstone as well as at the role of both intrinsic factors i e sandstone petrography and properties and extrinsic factors i e climatic and environmental influences since material sampling at the temple was limited to a few boreholes because of the high artistic rank of the building non destructive and low destructive in situ investigation methods like ultrasonic wave and drilling resistance measurements had to be applied to obtain information about the material properties of sandstone and their changes due to weathering moreover hydric swelling behaviour of the sandstone was determined on undecorated pieces of fallen blocks from the walls additional random test stable isotopic investigations of environmental influences and salts and thorough investigations of the spatial distribution of salts in the ashlars at two selected places with typical weathering patterns completed the set of data the results demonstrate that the weathering process is mainly triggered by rain dry cycles salt load found in the stone is composed of gypsum and nitrate compounds sulphur stable isotope investigations of potential sources of gypsum lead to the conclusion that soluble components of bat droppings are the major source of salts influences of environmental factors like sulphate in rainwater or so2 from the air on salt formation are unlikely gypsum may reinforce the surface deterioration due to high swelling shrinking movements of the sandstone 1 mm m during intensive wetting drying cycles

comment on last glacial maximum cirque glaciation in ireland and implications for reconstructions of the irish ice sheet quaternary science reviews 141 85 93

morphotectonic evidence from lateral propagation of an active frontal fold pakuashan anticline foothills of taiwan abstract the pakuashan anticline is uniquely suited for study of the forward and lateral growth of fault related folds the pakuashan ridge development arises from the late quaternary uplift of the most external thrust zone of the western foothills of taiwan from kaoshiung to taichung recent and active westward thrusting occurs at the front of the foothills the pakuashan anticline trending n 150 e in the northern part to n 000 in the southern part has been active throughout the quaternary period this activity is marked by geological structures tectonic geomorphology and seismicity a multisource and multiscale approach to study of the continental collision setting has been undertaken to combine tectonics sedimentology and geomorphology studies of fracture patterns allow identification of two main features of stress orientations a wnw ese compression direction and e w and n s extension directions quantitative geomorphic parameters have been used to define the morphotectonic evolution and to infer tectonic style along the mountain front geomorphic evidence provides significant information on the processes that govern lateral propagation of an active anticline quaternary terraces are uplifted tilted and folded over the pakuashan ridge drainage systems in areas of active compression give information on the thrust zone structures and their development steep drainage and high local relief indicate that the pakuashan anticline forms a well defined zone of high uplift especially in the southern part the two main controls on drainage in that area are rock strength in the hanging wall and propagation of the deformation towards the south

relative sea level changes glacial isostatic modelling and ice sheet reconstructions from the british isles since the last glacial maximum while contributing 1 m equivalent eustatic sea level rise the british isles ice sheet produced glacio isostatic rebound in northern britain of similar magnitude to eustatic sea level change or global meltwater influx over the last 18 000 years the resulting spatially variable relative sea level changes combine with observations from far field locations to produce a rigorous test for quantitative models of glacial isostatic adjustment local ice sheet history and global meltwater influx after a review of the attributes of relative sea level observations significant for constraining large scale models of the isostatic adjustment process we summarise long records of relative sea level change from the british isles and far field locations we give an overview of different global theoretical models of the isostatic adjustment process before presenting intercomparisons of observed and predicted relative sea levels at sites in the british isles and far field for a range of earth and ice model parameters in order to demonstrate model sensitivity and the resolving power available from using evidence from the british isles for the first time we show a good degree of fit between relative sea level observations and predictions that are based upon global earth and ice model parameters independently derived from analysis of far field data with a terrain corrected model of the british isles ice sheet that includes extensive glaciation of the north sea and western continental shelf that does not assume isostatic equilibrium at the last glacial maximum and keeps to trimline constraints of ice surface elevation we do not attempt to identify a unique solution for the model lithosphere thickness parameter or the local scale detail of the ice model in order to provide a fit for all sites but argue that the next stage should be to incorporate an ice sheet model that is based on quantitative glaciological model simulations we hope that this paper will stimulate this debate and help to integrate research in glacial geomorphology glaciology sea level change earth rheology and quantitative modelling copyright 2006 john wiley sons ltd

glacial trimlines to identify former ice margins and subglacial thermal boundaries a review and classification scheme for trimline expression abstract reconstructions of former ice sheets and glaciers provide important palaeoglaciological information about their behaviour in response to climate changes glacial trimlines record both the margin positions and palaeo ice thickness enabling the production of empirically constrained 3 dimensional reconstructions however the literature review into the characteristics interpretation and use of glacial trimlines here presented shows that these features have been under utilised and are poorly described in the existing literature with a confusing terminology currently in use a new classification scheme and terminology for trimline identification and interpretation is developed to better facilitate further research into these common features of glacierised and formerly glaciated landscapes

did large ice caps persist on low ground in north west scotland during the lateglacial interstade recent research based primarily on exposure ages of boulders on moraines has suggested that extensive ice masses persisted in fjords and across low ground in north west scotland throughout the lateglacial interstade greenland interstade 1 ca 14 7 12 9 ka and that glacier ice was much more extensive in this area during the older dryas chronozone ca 14 0 ka than during the younger dryas stade ca 12 9 11 7 ka we have recalibrated the same exposure age data using locally derived 10be production rates this increases the original mean ages by 6 5 12 implying moraine deposition between ca 14 3 and ca 15 1 ka and we infer a most probable age of ca 14 7 ka based on palaeoclimatic considerations the internal consistency of the ages implies that the dated moraines represent a single readvance of the ice margin the wester ross readvance pollen stratigraphic evidence from a lateglacial site at loch droma on the present drainage divide demonstrates deglaciation before ca 14 0 ka and therefore implies extensive deglaciation of all low ground and fjords in this area during the first half of the interstade ca 14 7 14 0 ka this inference appears consistent with lateglacial radiocarbon dates for shells recovered from glacimarine sediments and a dated tephra layer our revised chronology conflicts with earlier proposals that substantial dynamic ice caps persisted in scotland between 14 and 13 ka that large active glaciers probably survived throughout the lateglacial interstade and that ice extent was greater during the older dryas period than during the younger dryas stade copyright 2011 john wiley sons ltd