instantaneous end moraine and sediment wedge formation during the 1890 glacier surge of bruarjokull iceland abstract contemporary understanding of the behaviour of surging glaciers and ice streams is hampered by the lack of data on landsystem evolution and sedimentary environments this study concerns the ice marginal environment of the surge type bruarjokull in iceland the sediment distribution in the glacier forefield as well as the morphology sedimentology and tectonic architecture of the 1890 end moraine is investigated for highlighting the interaction between very dynamic ice and sediment landform associations as a result of substrate bedrock decoupling during the 1890 surge subglacial sediment was dislocated across the bedrock surface and deformed compressively leading to gradual substrate thickening and the formation of a sediment wedge in the marginal zone a drop in subglacial porewater pressure at the very end of the surge led to substrate bedrock coupling and a stress transfer up into the sediment sequence causing brittle deformation of the substrate simultaneously the glacier toe ploughed into the topmost part of the marginal sediment wedge initiating the moraine ridge construction fine grained and incompetent sediment deformed in ductile manner resulting in a narrow moraine dominated by rooted folds while coarse grained and competent sediment deformed in brittle fashion resulting in a wider moraine dominated by thrust blocks a new sequential model of subglacial and ice marginal processes operating during a glacier surge is proposed illustrating the stepwise formation of a marginal sediment wedge and an end moraine a twofold inseparable marginal end product that formed during the last days of the 1890 surge

theory of quantitative reconstruction of vegetation i pollen from large sites reveals regional vegetation composition quantitative reconstruction of past vegetation is one of the primary goals in quaternary palynology and palaeoecology but still remains difficult this paper proposes a model reveals that estimates regional vegetation composition using pollen from large lakes that have small site to site variations of pollen assemblages even if vegetation is highly heterogeneous once these data have been used to quantify regional vegetation composition within 104 105 km2 background pollen one of the parameters crucial for vegetation reconstruction can be estimated for smaller sized sites and incorporated into the landscape reconstruction algorithm lra a multistep framework for quantitative reconstruction of vegetation in smaller areas 104 ha simulations using the pollscape modelling show that reveals can provide accurate estimates of regional vegetation composition in various landscapes and under different atmospheric conditions if pollen assemblages from lakes that are much smaller than large lakes a

the practice of graphical fluid gradient interpretations of formation tester pressure data this paper presents a novel graphical enhancement technique that can be easily practiced to interpret reservoir fluid gradients with formation pressure test data the method has various applications including mapping reservoir fluid nature and trends identifying formation pressure changes because of facies changes or the presence of baffles or barriers and compartmentalization diagnosing fluid contact levels and transition zone intervals quality control of data and judging the reliability of gradient interpretation the scatter plotting technique is very useful not only for real time decision making at the well site during both wireline and drillpipe conveyed formation tester operations but also in routine data interpretation and reservoir studies with petrophysical logs pressure and fluid data

direct evidence of central european forest refugia during the last glacial period based on mollusc fossils abstract although there is evidence from molecular studies for the existence of central european last glacial refugia for temperate species there is still a great lack of direct fossil records to confirm this theory here we bring such evidence in the form of fossil shells from twenty strictly forest land snail species which were recorded in radiocarbon dated late glacial or older mollusc assemblages of nine non interrupted mollusc successions situated in the western carpathians and one in the bohemian massif we proposed that molluscs survived the last glacial period in central europe in isolated small patches of broadleaf forest which we unequivocally demonstrate for two sites of last glacial maximum age

exploration and assessment of the geothermal resources in the hammam faraun hot spring sinai peninsula egypt abstract the tectonic position of egypt in the northeastern corner of the african continent suggests that it may possess significant geothermal resources especially along its eastern margin the most promising areas for geothermal development in the northwest red sea gulf of suez rift system are located where the eastern shore of the gulf of suez is characterized by superficial thermal manifestations including a cluster of hot springs with varied temperatures magnetotelluric and gravity reconnaissance surveys were carried out over the geothermal region of hammam faraun to determine the subsurface electric resistivity and the densities that are related to rock units these surveys were conducted along profiles one dimensional 1d and two dimensional 2d inversion model techniques were applied on the mt data integrating the 2d inversion of gravity data the objectives of these surveys were to determine and parameterize the subsurface source of the hammam faraun hot spring and to determine the origin of this spring based on this data a conceptual model and numerical simulation were made of the geothermal area of hammam faraun the numerical simulation succeeded in determining the characteristics of the heat sources beneath the hammam faraun hot spring and showed that the hot spring originates from a high heat flow and deep ground water circulation in the subsurface reservoir that are controlled by faults these studies were followed by an assessment of the geothermal potential for electric generation from the hammam faraun hot spring the value of the estimated potential is 28 34 mw as the reservoir is assumed to be only 500 m thick this value would be enough for the desalination of water for both human and agricultural consumption

pollen based continental climate reconstructions at 6 and 21 ka a global synthesis subfossil pollen and plant macrofossil data derived from 14c dated sediment profiles can provide quantitative information on glacial and interglacial climates the data allow climate variables related to growing season warmth winter cold and plant available moisture to be reconstructed continental scale reconstructions have been made for the mid holocene mh around 6 ka and last glacial maximum lgm around 21 ka allowing comparison with palaeoclimate simulations currently being carried out as part of the fifth assessment report ar5 of the intergovernmental panel on climate change the synthesis of the available mh and lgm climate reconstructions and their uncertainties obtained using modern analogue regression and model inversion techniques is presented for four temperature variables and two moisture variables reconstructions of the same variables based on surface pollen assemblages are shown to be accurate and unbiased reconstructed lgm and mh climate anomaly patterns are coherent consistent between variables and robust with respect to the choice of technique they support a conceptual model of the controls of late quaternary climate change whereby the first order effects of orbital variations and greenhouse forcing on the seasonal cycle of temperature are predictably modified by responses of the atmospheric circulation and surface energy balance

ice age paleotopography a gravitationally self consistent theory of postglacial relative sea level change is used to infer the variation of surface ice and water cover since the last glacial maximum lgm the results show that lgm ice volume was approximately 35 percent lower than suggested by the climap reconstruction and the maximum heights of the main laurentian and fennoscandian ice complexes are inferred to have been commensurately lower with respect to sea level use of these ice age boundary conditions in atmospheric general circulation models will yield climates that differ significantly from those previously inferred on the basis of the climap data set

using species distribution models in paleobiogeography a matter of data predictors and concepts article i nfo the increasing interest in the effects of climate changes on species distributions has been followed by the development of species distribution models sdms although these techniques are starting to be used to study the location and dynamics of past species distributions a sound theoretical framework for their use in paleoecology is still lacking in this paper we are reviewing the main challenges for constructing paleo species distribution models to describe and project the past distribution of species namely data limitations selection of predictors and choice of a biologically relevant modeling procedure we also review and discuss the current state of the art in paleo sdms providing a series of recommendations for their use and proposing future research lines to improve the use of these techniques in paleobiogeography

palaeodistribution modelling of european vegetation types at the last glacial maximum using modern analogues from siberia prospects and limitations we modelled the european distribution of vegetation types at the last glacial maximum lgm using present day data from siberia a region hypothesized to be a modern analogue of european glacial climate distribution models were calibrated with current climate using 6274 vegetation plot records surveyed in siberia out of 22 initially used vegetation types good or moderately good models in terms of statistical validation and expert based evaluation were computed for 18 types which were then projected to european climate at the lgm the resulting distributions were generally consistent with reconstructions based on pollen records and dynamic vegetation models spatial predictions were most reliable for steppe forest steppe taiga tundra fens and bogs in eastern and central europe which had lgm climate more similar to present day siberia the models for western and southern europe regions with a lower degree of climatic analogy were only reliable for mires and steppe vegetation respectively modelling lgm vegetation types for the wetter and warmer regions of europe would therefore require gathering calibration data from outside siberia our approach adds value to the reconstruction of vegetation at the lgm which is limited by scarcity of pollen and macrofossil data suggesting where specific habitats could have occurred despite the uncertainties of climatic extrapolations and the difficulty of validating the projections for vegetation types the integration of palaeodistribution modelling with other approaches has a great potential for improving our understanding of biodiversity patterns during the lgm

recent drumlins flutes and lineations at vestari hagafellsjokull iceland in the foreland of the vestari hagafellsjokull glacier langajokull central iceland three scales of subglacial bed forms are found drumlins flutes and lineations the smaller bed forms are superimposed upon the larger these three bed forms probably formed as a result of the presence of a rigid subglacial core producing a lee side low pressure area into which sediment flowed and collected the cores of the drumlins are tumuli lava blisters whilst the cores of the flutes and lineations were large clasts differences between the three scales of bed forms are that a the flutes and lineations are far more mobile features as their cores could move within the deforming layer whilst the drumlin bedrock cores were fixed b the lineations formed in association with a clast pavement the change in scale of the bed forms may be related to changes in thickness of the deforming layer and size of the core at this site smaller bed forms were superimposed upon larger bed forms and these may have formed as the deforming layer progressively thinned in association with glacial retreat

sedimentary evidence of landscape and climate history since the end of mis 3 in the krkonose mountains czech republic abstract a sedimentary core recovered from the cirque basin of labsk d l valley 1039 m a s l in the krkonose mountains reflects the environmental history for approximately the last 30 000 years analyses of magnetic susceptibility carbon content pollen assemblages and macrofossil data in a 15 m thick sediment sequence provide the first continuous record of lateglacial and holocene vegetation history in sudetes region of the czech republic the succession of sedimentary units in the lower part of the core suggests that the cirque was ice free before the onset of the last glaciation at the beginning of marine isotope stage 2 highly variable climate prevailed during this period with cold conditions culminating about 18 cal ka bp cold climates persisted until the lateglacial period evidenced by an identified warming and subsequent cooling event correlated with the younger dryas period sparse treeless vegetation dominated in the catchment area at that time the sequence of interrupted thinly laminated silts reflects the retreat and temporary readvance of a local glacier in the cirque during 12 5 10 8 cal ka bp subsequently the alpine treeline ecotone gradually shifted above the cirque floor palaeoclimatic conditions in the early holocene fluctuated strongly whereas since 5 1 cal ka bp conditions have been more stable pollen based climate reconstructions suggest significant cooling at around 9 8 9 3 7 7 7 5 and 4 0 3 3 cal ka bp spruce forests have dominated the site since 5 0 cal ka bp when the vegetation became similar to the modern one two phases of increased sedimentation were identified within the holocene culminating about 9 2 7 5 cal ka bp and 5 8 5 5 cal ka bp sediment yield was as high as 2 4 mm yr 1 during the period reflecting environmental changes during the atlantic sub boreal transition

from surge type to non surge type glacier behaviour midre lovenbreen svalbard since the beginning of the 1900s the polythermal valley glacier midre lovenbreen area 5 km 2 in northwestern svalbard has retreated approximately 1km the glacier has not surged for at least 110 years and the present smooth longitudinal profile and negative mass balance suggest that it is not currently building up to a surge based on limited evidence it has often been assumed that midre lovenbreen surged around 1880 the ongoing retreat is probably due to quiescent phase stagnation amplified by 20th century climate change as is the case for several other glaciers in svalbard recently small eskers have been found in the glacier forefield based on their geomorphological appearance these are interpreted as concertina eskers and they add to the dynamic history of the glacier midre lovenbreen is interpreted as an example of a change from surge type to non surge type glacier behaviour

origin chronology and climatological significance of annual moraine ridges at myrdalsjokull iceland minor transverse moraine ridges have formed annually at the retreating north margin of myrdalsjokull 550 600 m a s l in south iceland during the period 1928 1981 they are composed of slabs of clast paved lodgement till and their formation at the glacier edge results from subglacial freezing on of sediment slabs during winter and the annual cycle of ice front activity this type of annual moraine ridge is likely to be characteristic of retreating temperate glaciers where the glacier toe is thin and winters are cold the speed of glacier retreat is finely balanced with changes in mean summer temperature suggesting that the short term ice front fluctuations are climatically induced and not a result of surge activity

the eyjabakkajokull glacial landsystem iceland geomorphic impact of multiple surges abstract a new glacial geomorphological map of the eyjabakkajokull forefield in iceland is presented the map covers c 60 km2 and is based on high resolution aerial photographs recorded in august 2008 as well as field checking landforms are manually registered in a geographical information system arcgis based on inspection of orthorectified imagery and digital elevation models of the area we mapped subglacially streamlined landforms such as flutes and drumlins on the till plain supraglacial landforms such as ice cored moraine pitted outwash and concertina eskers and ice marginal landforms such as the large multi crested 1890 surge end moraine and smaller single crested end moraines the glaciofluvial landforms are represented by outwash plains minor outwash fans and sinuous eskers extramarginal sediments were also registered and consist mainly of old sediments in wetlands or locally weathered bedrock eyjabakkajokull has behaved as a surge type glacier for 2200 years hence the mapped landforms originate from multiple surges landforms such as large glaciotectonic end moraines hummocky moraine long flutes crevasse fill ridges and concertina eskers are characteristic for surge type glaciers the surging glacier landsystem of eyjabakkajokull serves as a modern analog to the landsystems of terrestrial paleo ice streams

glacial landsystems of satujokull iceland a modern analogue for glacial landsystem overprinting by mountain icecaps mapping of the surficial geology and geomorphology of the satujokull foreland of the northern hofsjokull ice cap in central iceland provides a clear signature of glacial landsystem overprinting as a result of complex glacier behaviour during the historical period landsystem 1 comprises a wide arc of ice cored moraine and controlled ridges lying outside fluted and drumlinized terrain and is indicative of polythermal conditions this landform assemblage commonly marks the historical little ice age maximum limit on the forelands of upland icefields in the arid interior of iceland and is therefore a record of climatically driven glacier advance landsystem 2 contains most of the diagnostic criteria for the surging glacier landsystem and records two separate surges by the western margin of satujokull in the period since the attainment of the little ice age maximum advance the occurrence of landsystem 2 is significant because satujokull has not been previously regarded as a surging glacier even though other outlets of hofsjokull are prone to surging landsystem overprinting especially in response to changing thermal regimes and or glacier dynamics and particularly by different flow units in the same glacier is rarely reported but is crucial to the critical application of modern landsystem analogues to quaternary palaeoglaciological reconstruction

late quaternary expansion of norway spruce picea abies l karst in europe according to pollen data abstract lateglacial and holocene expansion of norway spruce picea abies l karst in europe is reconstructed in steps of 1000 radiocarbon years on the basis of pollen data collected from literature and databases pollen thresholds for the lateglacial of 0 1 2 5 and 10 and for the holocene of 2 were used spruce pollen representation and limitations of pollen data are discussed we assume that the 2 threshold tracks the advance of the main spruce front but might fail to detect small populations or those present in low density the history of spruce expansion was distinctly different in northern and southern parts of its range 1 in ne europe spruce expanded during the allerod reaching southwards to n byelorussia during the younger dryas spruce populations contracted north of ca 60 n but expanded strongly in the region approximately 53 60 n 23 32 e where they declined at the beginning of the holocene we infer that the lateglacial expansion in ne europe concerned mainly p abies subsp obovata 2 holocene expansion in n europe concerned mainly p abies subsp abies southward expansion within the northern range is continuing to the recent millennium 3 in central europe spruce expanded vigorously during the allerod contracted or stagnated during the younger dryas and then strongly re expanded during the preboreal following the simple expectation that climatic warming had a positive impact on its development 4 holocene westward and northward expansion of spruce in its southern range central europe was rapid 10 8 ka 14 c bp very slow 8 6 ka 14 c bp and rapid 6 5 ka 14 c bp when the present day western limits were reached 5 the 2 spruce pollen threshold is too high to detect the fact that the northern and southern ranges of spruce have joined in the holocene the persistence of low spruce abundance in the transitional area is explained mainly by the strong anthropogenic deforestation ever since spruce grew there

compartmentalization and time lapse geochemical reservoir surveillance of the horn mountain oil field deep water gulf of mexico oil is produced at the horn mountain field gulf of mexico mississippi canyon blocks 126 and 127 from middle miocene reservoirs m and j reservoir facies are characterized as sand filled channels and associated overbank deposits and are positioned in combination structural and stratigraphic traps prior to initial production several barriers and baffles were identified in both reservoirs by integrating geological geophysical petrophysical pressure pvt pressure volume temperature relationships and geochemical data and petroleum filling history a compartmentalization risk matrix was developed to facilitate and visualize the integrated evaluation of compartmentalization during production in addition to traditional surveillance technologies we applied time lapse geochemistry tlg to visualize petroleum sweep by monitoring changes in fluid composition and fingerprints across reservoirs in this technology appraisal and preproduction fluid samples are first analyzed to map fluid types across a static reservoir then a surveillance program in which fluid samples are taken from producing wells at regular time intervals is designed and executed the obtained production samples are geochemically fingerprinted and compared with preproduction fluids from the same well and surrounding wells at horn mountain interpretation of geochemical data allowed us to infer oil movement across reservoir m and helped to reevaluate reservoir models and reduce risks in managing reservoir performance in reservoir j an untapped compartment was identified and an additional producer was justified for future drilling time lapse geochemistry results were consistent with and complimentary to other surveillance data available to date our study demonstrates that tlg is a safe and cost effective technology which reduces uncertainties associated with other reservoir surveillance methods and appears to be valuable for reservoir management

concertina eskers bruarjokull iceland an indicator of surge type glacier behaviour abstract bruarjokull is a surging outlet lobe of vatnajokull in se iceland geological evidence indicates that during quiescent phases water drainage takes place in ice walled and ice roofed channels as the glacier retreats the courses of these channels are represented by eskers eskers which were englacial prior to surges become deformed during a surge the deformation of eskers reflects strong longitudinal compression of the ice in the terminal zone the wavelength of one of the compressed eskers indicates that ice in a 4 km wide margin was compressed by 50 of its original length compressed or concertina eskers date from the 1963 1964 and the 1890 surges of bruarjokull they have not been found from the 1810 surge indicating that they may not survive if overrun by subsequent surges

causes of model data discrepancies in european climate during oxygen isotope stage 3 with insights from the last glacial maximum abstract oxygen isotope stage 3 ois 3 encompassing the long middle section of the last glacial interval has been the focus of an intensive high resolution climate modeling effort for europe these model simulations produce substantially colder climates than modern simulations however the temperatures appear warmer than many proxy indicators suggest in order to evaluate the importance of the model boundary conditions comparable simulations are completed for the last glacial maximum lgm the lgm simulation produces a much colder european continent than ois 3 despite similarities in the specification of sea surface temperatures ssts ice sheet dimension is evidently a key factor in explaining the difference in european climates over the past 40 000 yr however underestimates in specified ois 3 ice sheets cannot be invoked to explain the discrepancies since data strongly indicate small ice sheet extents at that time this leaves errors in specified ois 3 ssts as the most likely cause

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

geomorphology and sedimentology of surging glaciers a land systems approach the identification of surging glaciers and ice streams in glaciated landscapes is of major importance to the understanding of ice sheet dynamics and for reconstructing ice sheets and climate no single landform or diagnostic criterion has yet been found with which to identify surging glaciers a surging glacier land system model is constructed using observations and measurements from contemporary surging glacier snouts in iceland svalbard u s a and canada for differentiating ancient surging margins from other non surging palaeoglaciers this integrates the suite of landforms sediments and stratigraphy produced at surging glacier margins landforms produced during surging include thrust moraines concertina eskers and subglacial crevasse squeeze ridges sedimentary sequences are usually characterized by multiple stacked diamictons and stratified interbeds which display severe glaciotectonic contortion and faulting hummocky moraine comprising interbedded stratified sediments and mass flow diamictons has also been associated with surge margins where large quantities of supraglacial and englacial debris entrained during the surge event have melted out in situ an example of the application of the land system model is presented for east central alberta canada a surging palaeo ice stream is identified within this part of the southwestern laurentide ice sheet where thrust block moraines crevasse squeeze ridges flutings hummocky moraine and glaciotectonized sediments are juxtaposed

sea level at the last glacial maximum evidence from northwestern australia to constrain ice volumes for oxygen isotope stage 2 new sea level information from the bonaparte gulf in northwestern australia is used to constrain the magnitude and rates of change of ice volumes during the last glacial maximum lgm the region is tectonically stable and far from the former ice covered regions the glacio hydro isostatic adjustment of the coast is therefore relatively small and the corrections for this evect are not sensitive to details of the rebound model microfossil analysis and ams radiocarbon dating of 11 gravity cores taken across the shelf and bonaparte gulf demonstrate that 1 the lgm sea levels were locally at 125 4 m 2 the lgm terminated abruptly at 19 000 cal yr bp with a rapid rise in sea level of about 15 m over the next 500 years and 3 the onset of the minimum sea levels occurred before 22 000 cal yr bp when corrected for the glacio hydro isostatic evects the increase of lgm ice volumes over the present day ice volume is 52 5 106 km3 the termination of the lgm is marked by a rapid ice discharge of 5 2 106 km3 2001 elsevier science b v all rights reserved

last glacial maximum temperatures over the north atlantic europe and western siberia a comparison between pmip models margo sea surface temperatures and pollen based reconstructions abstract evaluating the ability of models to simulate climates different from the modern one is important for climate prediction here we present a first comparison between results from simulations of the last glacial maximum climate and continental and surface ocean reconstructions for the north atlantic europe and western siberia the simulations include prescribed sea surface temperature sst and slab ocean atmospheric general circulation model runs performed within the pmip1 project and atmosphere ocean fully coupled runs performed after pmip1 and within the pmip2 project the surface ocean reconstructions are from the margo project continental reconstructions are based on pollen data over the north atlantic most models simulate the strengthening of the sst meridional gradient suggested by the reconstructions but most do not reproduce the lgm control sst anomaly at the right location nor with the right amplitude over western siberia the model results are much improved when a new ice sheet reconstruction ice 5g is used to force the models the main discrepancy remains for western europe winter temperatures for which lgm control anomalies are significantly underestimated by all models all models indicate that this region during the lgm experienced significantly higher interannual variability in coldest month temperatures compared to the control runs this increased variability could have conspired to bias the apparently extremely cold pollen based temperature reconstructions

last glacial maximum and holocene climate in ccsm3 abstract the climate sensitivity of the community climate system model version 3 ccsm3 is studied for two past climate forcings the last glacial maximum lgm and the mid holocene the lgm approximately 21 000 yr ago is a glacial period with large changes in the greenhouse gases sea level and ice sheets the mid holocene approximately 6000 yr ago occurred during the current interglacial with primary changes in the seasonal solar irradiance the lgm ccsm3 simulation has a global cooling of 4 5 c compared to preindustrial pi conditions with amplification of this cooling at high latitudes and over the continental ice sheets present at lgm tropical sea surface temperature sst cools by 1 7 c and tropical land temperature cools by 2 6 c on average simulations with the ccsm3 slab ocean model suggest that about half of the global cooling is explained by the reduced lgm concentration of atmospheric co2 50 of present day concentrations there is an increase in the antarctic circumpolar current an

active drumlin field revealed at the margin of mulajokull iceland a surge type glacier abstract recent marginal retreat of mulajokull a surge type outlet glacier of hofsjokull iceland has revealed a drumlin fi eld consisting of more than 50 drumlins the drumlins are 90 320 m long 30 105 m wide 5 10 m in relief and composed of multiple beds of till deposited by lodgment and bed deformation the youngest till layer truncates the older units with an erosion surface that parallels the drumlin form thus the drumlins are built up and formed by a combination of subglacial depositional and erosional processes field evidence suggests each till bed to be associated with individual recent surges we consider the fi eld to be active in the sense that the drumlins are shaped by the current glacial regime the mulajokull fi eld is the only known active drumlin fi eld and is therefore a unique analogue to pleistocene drumlin fi elds

glacial landsystems of the southwest laurentide ice sheet modern icelandic analogues landform assemblages and associated stratigraphy sedimentology and structure are used in the reconstruction of palaeo ice sheet dynamics in alberta western canada interpretations are based upon the modern analogues from four outlet glaciers at the margins of vatnajokull and myrdalsjokull iceland in the area between lloydminster and lac la biche central alberta an extensive landform assemblage of megaflutings crevasse squeeze ridges and thrust block moraine arcs document the former surging of part of the margin of the laurentide ice sheet during later stages of recession this landform assemblage including numerous exposures of glacitectonised bedrock and quaternary sediments is comparable to the landsystem of the surging glaciers eyjabakkajokull and bruarjokull in iceland near high river southern alberta the former existence of an ice lobe characterised by active recession is recorded by closely spaced low amplitude recessional push moraines that drape tunnel valleys these are comparable in form and pattern to annual push moraines and fluted till surfaces produced by breidamerkurjokull and sandfellsjokull iceland and also include rimmed depressions produced by the escape of artesian water during ice marginal pushing this study provides interpretations of the regional glacial geomorphology of alberta based upon comparisons of form and stratigraphy with modern glacial analogues and provides an alternative to recent models which invoke large floods of subglacial meltwater to explain many of these same features implications for ice dynamics and regional till stratigraphies are discussed copyright 1999 john wiley sons ltd

last glacial vegetation of northern eurasia in order to investigate the potential role of vegetation changes in megafaunal extinctions during the later part of the last glacial stage and early holocene 42 10 ka bp the palaeovegetation of northern eurasia and alaska was simulated using the lpj guess dynamic vegetation model palaeoclimatic driving data were derived from simulations made for 22 time slices using the hadley centre unified model modelled annual net primary productivity anpp of a series of plant functional types pfts is mapped for selected time slices and summarised for major geographical regions for all time slices strong canonical correlations are demonstrated between model outputs and pollen data compiled for the same period and region simulated anpp values especially for tree pfts and for a mesophilous herb pft provide evidence of the structure and productivity of last glacial vegetation the mesophilous herb pft anpp is higher in many areas during the glacial than at present or during the early holocene glacial stage vegetation whilst open and largely treeless in much of europe thus had a higher capacity to support large vertebrate herbivore populations than did early holocene vegetation a marked and rapid decrease in anpp of mesophilous herbs began shortly after the last glacial maximum especially in western eurasia this is likely implicated in extinction of several large herbivorous mammals during the latter part of the glacial stage and the transition to the holocene

application of three fault growth criteria to the puente hills thrust system los angeles california usa abstract three dimensional mechanical models are used to evaluate the performance of different fault growth criteria in predicting successive growth of three echelon thrust faults similar to the segments of the puente hills thrust system of the los angeles basin california four sequential boundary element method models explore the growth of successive echelon faults within the system by simulating snapshots of deformation at different stages of development these models use three criteria 1 energy release rate 2 strain energy density and 3 navier coulomb stress to characterize the lateral growth of the fault system we simulate the growth of an echelon thrust fault system to evaluate the suitability of each of these criteria for assessing fault growth each of these three factors predicts a portion of the incipient fault geometry i e location or orientation however each provides different information in each model energy release rate along the westernmost leading tip of the puente hills thrust drops with growth of the next neighboring fault this result supports the overall lateral development of successive echelon segments within each model regions of high strain energy density and navier coulomb stress envelope at least a portion of the next fault to develop although the strain energy density has stronger correlation than navier coulomb stress to the location of incipient faulting in each model one of the two predicted planes of maximum navier coulomb stress ahead of the leading fault tip matches the strike but not the dip of the incipient fault plane recreating part of the fault orientation the incipient fault dip is best predicted by the orientation of the strain energy density envelopes around the leading fault tip furthermore the energy release rate and pattern of strain energy density can be used to characterize potential soft linkage overlap or hard linkage connection of echelon faults within the system

the wurm in nw iberia a pollen record from area longa galicia the pollen record at area longa is the westernmost sequence available for investigation of the last glaciation in continental europe it is located in a region nw iberia for which data from times earlier than the late glacial period are scarce it comprises a series of exposed limnetic levels that lie above an eemian oxygen isotope stage ois 5e beach and are separated by inorganic layers the oldest limnetic level level i attributed to the early glacial period ois 5a to ois 5d shows a dominance of woodland with high proportions of fagus pollen and is tentatively identified with st germain i the lower pleniglacial ois 4 level ii records a stadial landscape of grassland and shrub level iii from the pleniglacial interstade ois 3 reflects a complex period in which three warmer woodland phases alternated with periods of more open vegetation this cyclical behavior correlates with the ice core isotope record and with the general tendencies observed in other wurmian pollen records but the composition of our pollen profiles differs from those observed in these other records in nw iberia the dominant trees were deciduous taxa not conifers of particular note is the presence of lowland fagus woodlands during the pre wurm and the occurrence of carpinus considerably farther west than the boundary of its current distribution in the iberian peninsula

subglacial decoupling at the sediment bedrock interface a new mechanism for rapid flowing ice abstract in undetermined on millennial or even centennial time scales the activity of rapid flowing ice can affect climate variability and global sea level through release of meltwater into the ocean and positive feedback loops to the climate system at the surge type glacier bruarjokull an outlet of the vatnajokull ice cap eastern iceland extremely rapid ice flow was sustained by overpressurized water causing decoupling beneath a thick sediment sequence that was coupled to the glacier this newly discovered mechanism has far reaching consequences for our understanding of fast flowing ice and its integration with sediment discharge and meltwater release c 2006 elsevier ltd all rights reserved

the active temperate glacial landsystem a model based on breiðamerkurjokull and fjallsjokull iceland accurate interpretations of ancient glaciated terrains rely heavily on our knowledge of process form relationships in contemporary glacierized basins a landsystems model for temperate actively receding glaciers is presented based upon brei amerkurjokull and fjallsjokull iceland historical documentation maps and or aerial photography documenting recession since 1903 provide a unique series of snapshots of the evolving glacial geomorphology at these snouts this documentation is employed in association with sedimentological investigations to assess the evolution of sediment landform assemblages at active temperate glacier margins using the wealth of geomorphological and sedimentological information produced during the recent recession of brei amerkurjokull and fjallsjokull three depositional domains are recognized 1 areas of extensive low amplitude marginal dump push and squeeze moraines derived largely from material on the glacier foreland and often recording annual recession of active ice 2 incised and terraced glacifluvial forms such as recessional ice contact fans and hochsandur fans and simple and complex anabranched eskers and small areas of pitted outwash 3 subglacial landform assemblages of flutes drumlins and overridden push moraines located between ice marginal glacifluvial depo centres the lack of supraglacial sediment in active temperate glaciers like brei amerkurjokull and fjallsjokull generally precludes the widespread development of chaotic hummocky moraine the hummocky terrain previously termed kame and kettle topography has mostly evolved by melt out into a complex network of anabranched eskers over the period 1945 1998 or actually comprises pitted or kettled outwash sandar the tills across the foreland were emplaced by subglacial deformation and lodgement and comprise materials derived from pre existing stratified sediments in addition to localized abrasion of rock surfaces and patches of lake sediments till sequences thicker than 2 m have been constructed by the sequential plastering of till layers onto stratified sediments and bedrock because this stacking is a sub marginal process it is suggested that complex till sequences similar to those observed at brei amerkurjokull fjallsjokull may be employed in the reconstruction of ancient glacier margins additionally the geomorphology of the active temperate landsystem at east brei amerkurjokull may contain subtle surge signatures verifying the historical record of small surges by this part of the glacier this illustrates the danger of employing landform sediment associations from restricted study areas e g parts of landsystems as representative process form models for glaciated terrains

the drumlin field and the geomorphology of the mulajokull surge type glacier central iceland article i nfo herewe presenta newgeomorphological mapof the active drumlin field and theforefieldof mulajokull a surge type outlet glacier iceland the map is based on aerial photographs taken in 1995 and lidar data recorded in 2008 mapping was done using arcgis 10 software on orthorectified imagery lidar data and digital elevation models the mapped landforms were initially identified on the aerial imagery and lidar and then ground checked in the field we mapped subglacial supraglacial ice marginal periglacial and glaciofluvial landforms the geomorphology of the mulajokull forefield is similar to that of the forefields of other surge type glaciers in iceland with a highly streamlined forefield crevasse fill ridges and series of glaciotectonic end moraines how ever thelargenumber i e 110 of drumlinsformingthe drumlin fieldisuniqueformodernicelandicsurge type glaciersand as yet unique for contemporary glaciersingeneral also apparent isthat thedrumlins are widerand shorter in the distal part of the drumlin field and narrower and longer in the proximal part hence the mapping reveals a development of the drumlins toward a more streamlined shape of the proximal landforms that have experienced more surges the drumlins in the drumlin field are active i e they form during the modern surges of mulajokull

the final phase of dead ice moraine development processes and sediment architecture kotlujokull iceland consecutive phases of de icing of ice cored moraines and the formation of dead ice moraine were monitored over a 4 year period at the terminus of the kotlujokull glacier iceland particularly the transition from partially ice cored moraine with isolated dead ice blocks to the ice free landscape receives attention in this paper in order to link the final melting processes to the architecture of the sedimentary end product in the current humid sub polar climate of south iceland de icing of partially ice cored moraines results chiefly from melting along the bottom surface of ice cores with an annual average rate of 25 cm the final de icing is associated with an interrelated group of re sedimentation processes and surface features series of sinkholes evolve at the toe of dead ice blocks which initiate retrogressive rotational sliding or backslumping of the ice cored slopes and the formation of distinct edges and fractures in the adjacent basins although backslumping is the dominant process in this phase of re sedimentation structures resulting from this process are rarely recognized in the ice free landscape as ice cores gradually diminish the effect of the latest re sedimentation events will overprint or destroy most existing sedimentary characteristics thus in the ice free landscape structures mainly related to the formation of sinkholes and fractures remain imprinted on the sediment succession generally no inversion of the topography occurs during the final phase of de icing the overall topography recognized in the late phase of the fully ice cored terrain is merely lowered and the amplitude of the relief reduced as de icing progresses the sediment architecture of the ice free landscape is characterized by heterogeneous and often slumped diamict sediments with variable thickness and lateral distribution clast orientation is related to the direction of slopes and boulders are found in isolated groups or in linear arrangements

describing a drowned pleistocene ecosystem last glacial maximum vegetation reconstruction of the palaeo agulhas plain abstract pleistocene ecosystems provided the stage for modern human emergence terrestrial vegetation communities structure resources for human foragers providing plant food wood for fuel and tools and fibre as well as habitat for animal prey the pleistocene distribution of vegetation communities is seldom considered as a key constraint on hunter gatherers foraging across the landscape we used modern vegetation patterns along the cape south coast to develop a rule based model of the expected vegetation for a given soil type precipitation regime and fire regime we then applied this ruleset to present day environmental conditions to test and validate the model we also scaled the climate vegetation ruleset to account for likely effects of low atmospheric co2 and lower temperature in the last glacial maximum lgm on plant water use efficiency the model was then used to postdict vegetation patterns for the lgm using palaeo landscape reconstruction of geological substrata and soils and palaeoclimate simulations this palaeoscape comprised the extensive palaeo agulhas plain pap which was exposed at lower sea levels during glacial periods our model predicts that the pap was dominated by limestone fynbos in its southern part and by shale grassland with cappings of dune fynbos thicket mosaic in the north shale and sandstone fynbos were restricted to the western zone which experienced a stronger winter rainfall regime during the lgm than at present the entire pap was dissected by broad and shallow floodplains supporting a mosaic of woodland and grassland on fertile alluvial soils this savanna like vegetation as well as shale grassland are poorly represented in the modern landscape and would have been capable of supporting the diverse megafauna typical of glacial periods these pleistocene periods would have presented a very different resource landscape for early modern human hunter gatherers than the interglacial landscape such as is found in the cape coastal lowlands today

the vegetation of the russian plain during the second part of the late pleistocene 33 18 ka abstract the paleofloral records from 108 sections of the russian plain for the briansk interstadial 33 24 ka and the maximum of the late valdai glaciation 24 18 ka have been combined in a palynological database a series of electronic maps of indicator plant species and different plant communities determining certain vegetation paleophytocoenoses and the landscape as a whole were reconstructed forest communities occurred fragmentarily they were mainly associated with dissected areas subarctic and steppe plants were represented almost everywhere the predominance of open landscapes periglacial steppe and periglacial forest steppe formations during the middle and late valdai on the russian plain indicates a moderately cold climate during the briansk interstadial and a cold continental climate during the late valdai glaciation

subglacial bedforms of the zemgale ice lobe south eastern baltic abstract presented in this paper are the results of the mapping of 6600 subglacial bedforms of the zemgale ice lobe zil their composition and internal structure in the south eastern baltic region topographic maps at scale 1 10 000 were mainly used to map bedforms in latvia while a digital elevation model with cell size of 5 m was used for north central lithuania the zil operated during the deglaciation of the late weichselian scandinavian ice sheet sis at least in the middle lithuanian and north lithuanian glacial phases and created a subglacial landform assemblage consisting of glacial lineations such as drumlins mega flutings mega scale glacial lineations msgls and transversal morphologies such as ribbed moraines it is observed that lineations of different scales co exist suggesting subglacial bedform transition and possibly a continuum of bedforms highly elongated lineations with a length of up to 24 km and an elongation ratio of up to 1 50 interpreted as msgls are observed in the ne part of the middle lithuanian plain in the so called zemgale drumlin field 20 of lineations have elongation ratios 10 1 indicating the fastest ice flow in the central part of the main body of the lobe based on test surveys and investigated outcrops the drumlin cores consist of sorted sediments with different levels and depths of glaciotectonic deformation overlain by subglacial till the main drumlin forming ice stress was mostly parallel to the crests of drumlins while some ice stress from inter drumlin depressions acted during the final episodes of their formation the observed sediment structures indicate multiple episodes of the basal ice bed coupling and decoupling which can best be explained by the mosaic ice bed deformation model ribbed moraines are characterized by a complicated structure of multiple till units interbedded with sorted sediments that have been formed by repeated subglacial overthrusting

improved interpretation of wireline pressure data modern wireline pressure data can have resolution and reproducibility sufficient to detect small fluid density changes and pressure barriers yet these features are commonly overlooked on conventional pressure depth plots the large pressure variation caused by weight of subsurface fluids hides these subtle features excess pressure is the pressure left after subtracting the weight of a fluid from the total pressure this concept is applied to wireline pressure data to remove effects of weight and emphasize subtle pressure differences caused by density variations and pressure barriers fluid density changes of 0 02 g cm3 or less can be resolved and within well pressure barriers in the order of 5 kpa 0 7 psi can be detected using good quality data effects of reservoir capillary displacement pressure can be detected by offset of the free water level from the petroleum water contact this effect can be used to estimate reservoir wettability subsurface fluid density measurements can also be used to evaluate oil or gas quality on a bed by bed scale in traps having variable oil or gas composition to detect compartmentalization by small petroleum density differences to verify quality of samples for pvt pressure volume temperature analysis and estimate salinity or temperature of unsampled water zones data quality limits barrier and fluid contact resolution thus quality control is essential pressure measurement errors on the 3 kpa 0 5 psi scale can be detected from behavior of the buildup pressure tests having the potential for small amounts of supercharge are identified from the overbalance and formation mobility examples illustrate identification of free water levels and fluid contacts fluid identification supercharge identification and water zone compartmentalization

combination of remote sensing gis and palaeohydrologic remarks for promoting the exploitation of water resources in the sahara cases from the red sea coast egypt the current work presents an integrated approach to maximize groundwater exploitation under sahara conditions the approach includes investigation of palaeohydrology remote sensing data field verification and geophysical datasets gravity aeromagnetic and geoloelectrical data results reveal the existence of palaeohydrologic remarks such as palaeodriange terraces tufas gorges and alluvial fans the hydrogeological investigation reflects that the quaternary groundwater existed under free water table conditions with water depths range between 5 06 and 50 m from the ground while the miocene aquifer has water depths vary between 22 m of shallow wells and 108 m of deep wells the study illustrates the presence of the tectonic fallen zones tfz where the precambrian rocks show throw down blocks associated with a set of faults and covered by thick sedimentary succession the tfz with their faults nw se and ne sw are attributed to the regional red sea rift where these faults can provide groundwater recharge opportunities the groundwater occurrences in the tfz indicate saturation thickness ranges between 75 and 175 m for miocene aquifer and between 50 and 180 m for nubian sandstone aquifer a total of 22 basins were analyzed where their morphometric parameters indicate the possibility of groundwater accumulations the obtained stable isotopes compositions of hydrogen d and oxygen 18o reveal that aquifers were recharged throughout the previous wetter climate with reasonable contributions during intervening arid periods due to the continued and urgent need for water in the sahara the obtained results can be utilized to develop applied recommendations for future groundwater exploration

climatic patterns over the european alps during the lgm derived from inversion of the paleo ice extent abstract quaternary climate has been dominated by alternating glacial and interglacial periods while the timing and extent of past ice caps are well documented local variations in temperature and precipitation as a response to cyclic glaciations are not resolved resolving these issues is necessary for understanding regional and global climate circulation in particular the impact of the cold high pressure zone above the fennoscandian ice cap on the position of the jet stream in europe and a possible change in the direction and the source of moisture flow are still debated here we reconstruct climate conditions that led to the observed ice extent in the european alps during the last glacial maximum lgm using a new inverse method to reconstruct the spatially variable position of the equilibrium line altitude ela we investigate whether the alpine lgm ice cap dominantly received precipitation in the south due to a strong southward shift of the westerlies in midlatitudes we report inversion results that enable us to estimate the role of climate inversion method parameters ice dynamics flexure and topography in modulating the inferred equilibrium line altitude our main finding is the increase of the position of the ela from west to east and from north to south of the mountain range which suggest dominant moisture delivery over the alps during the lgm relatively similar to today

identification and characteristics of surge type glaciers on novaya zemlya russian arctic we present a comprehensive new inventory of surge type glaciers on the novaya zemlya archipelago using high resolution up to 4 m satellite imagery from 1976 77 hexagon 1989 landsat tm 2001 landsat etm and 2006 aster a total of 692 glaciers and their forelands were observed for glaciological and geomorphological criteria indicative of glacier surging e g looped moraines heavy surface crevassing surface potholes thrust block moraines concertina eskers this enabled the identification of 32 potential surge type glaciers compared with four previously identified representing 4 6 of the total but 18 by glacier area we assess the characteristics of surge type glaciers surge type glaciers are statistically different from non surge type glaciers in terms of their area length surface slope minimum elevation mid range elevation and terminus type they are typically long median length 18 5 km large median area 106 8 km 2 outlet glaciers with relatively low overall surface slopes median slope 1 7 and tend to terminate in water marine or lacustrine they are predominantly directed towards and located in the more maritime western region of the russian arctic and we suggest that surge occurrence might be related to large and complex catchment areas that receive increased delivery of precipitation from the barents sea

sphagnum peatland distribution in north america and eurasia during the past 21 000 years the distribution and abundance of sphagnum spores in north america and eurasia are mapped for the past 21 ka the present day distribution of abundant sphagnum spores corresponds closely to areas with peatland development with maximum sphagnum abundance between 630 and 1300 mm annual precipitation and between 2 and 6 c mean annual air temperature during the wisconsin glaciation there were apparently not large areas of peatland in north america except in alaska high sphagnum spore percentages were found in eastern north america during deglaciation major peatland development occurred in boreal north america after 9 ka and there was a southward movement of high sphagnum spore abundance after 5 ka in the western great lakes region major peatland development began after 9 ka in europe and asia on the basis of maps of the area supporting peatlands carbon accumulation in peatlands is estimated to be low prior to 11 ka increased slightly between 11 and 5 ka and greatly increased during the past 5 ka

modelling the last glacial maximum environments for a refugium of pleistocene biota in the russian altai mountains siberia abstract recent botanical and zoological studies have suggested that the altai mountains in southern siberia are an important refugium of the last glacial biota that used to be widespread across northern eurasia before the pleistocene holocene transition to obtain insights into the history of this relict biota we modelled the spatial distribution of habitats during the last glacial maximum lgm in the russian altai we prepared a map of the current vegetation of this area based on the ground truthed remote sensing data and modelled the distribution of the current vegetation types using the random forest technique with climatic predictors the models were projected onto the ccsm3 model of the lgm climate for the russian altai and interpreted for 72 of its area because the remaining part is supposed to have been glaciated during the lgm the models projected lgm predominance of desert steppe across most of the non glaciated area of the russian altai probably associated with areas of typical steppe tundra grasslands and some other habitat types including forest patches in stream valleys it is likely that during the lgm these habitats supported the cold adapted open landscape biota in the holocene most of the previous grassland area changed into forest or forest steppe and the pleistocene biota retreated with the exception of the chuya basin and the ukok plateau in the southeast where the habitat change was very small and desert steppe and associated vegetation types remained preserved this refugial area is currently rich in the relict pleistocene species a different history was suggested for the precipitation rich area in the northernmost altai north of lake teletskoye where the lgm models suggested occurrence of patches of open forest of larix sibirica and pinus sibirica in forest tundra and forest steppe landscapes these forests may have provided the lgm refugium for the temperate forest species that currently occur in this precipitation rich area

red sea rifting controls on aquifer distribution constraints from geochemical geophysical and remote sensing data highly productive wells in the central eastern desert of egypt are tapping groundwater in subsided blocks of jurassic to cretaceous sandstone taref formation of the nubian sandstone group and oligocene to miocene sandstone nakheil formation now occurring beneath the red sea coastal plain and within the proximal basement complex aquifer development is related to red sea rifting 1 rifting was accommodated by vertical extensional displacement on preexisting nw se to n s trending faults forming a complex array of half grabens and asymmetric horsts and 2 subsided blocks escaped erosion accompanying the red sea related uplift subsided blocks were identifi ed and verifi ed using satellite data geologic maps and fi eld and geophysical investigations interpretations of very low frequency vlf measurements suggest the faults acted as conduits for ascending groundwater from the subsided aquifers stable isotopic compositions d 19 3 to 53 9 18 o 2 7 to 7 1 of groundwater samples from these aquifers are interpreted as mixtures of fossil up to 70 and modern up to 65 precipitation groundwater volumes in subsided blocks are large within the central eastern desert basement complex alone they are estimated at 3 10 9 m 3 and 10 10 9 m 3 for the

ice volume changes bias estimation of mass balance measurements and changes in subglacial lakes derived by lidar mapping of the surface of icelandic glaciers icelandic glaciers cover 11 000 km2 in area and store 3600 km3 of ice starting in 2008 during the international polar year accurate digital elevation models dems of the glaciers are being produced with airborne lidar more than 90 of the glaciers have been surveyed in this effort including vatnajokull hofsjokull myrdalsjokull drangajokull eyjafjallajokull and several smaller glaciers the publicly available dems are useful for glaciological and geological research including studies of ice volume changes estimation of bias in mass balance measurements studies of jokulhlaups and subglacial lakes formed by subglacial geothermal areas and for mapping of crevasses the lidar mapping includes a 500 1000 m wide ice free buffer zone around the ice margins which contains many glacio geomorphological features and therefore the new dems have proved useful in geological investigations of proglacial areas comparison of the lidar dems with older maps confirms the rapid ongoing volume changes of the icelandic ice caps which have been shown by mass balance measurements since 1995 96 in some cases ice volume changes derived by comparing the lidar measurements with older dems are in good agreement with accumulated ice volume changes derived from traditional mass balance measurements but in other cases such a comparison indicates substantial biases in the traditional mass balance records

glacial refugia and mid holocene expansion delineate the current distribution of castanea sativa in europe areas of quaternary refugia for tree species have been mainly delineated based on fossil records and phylogeography but niche modelling can provide useful complementary information here we use palaeodistribution modelling to test the main hypotheses about the distribution of castanea sativa in the last glacial maximum lgm and the mid holocene in europe we computed distribution models for current climatic conditions using different methods and projected them onto three climatic scenarios for the lgm and the mid holocene the projections were validated with pollen and charcoal records lgm refugia were suggested in the north of the iberian italian and balkan peninsulas and in northern anatolia the projections for the mid holocene indicated high climatic suitability and geographic expansion of the species range across southern europe including some areas where the species is nowadays considered as non native in general our models are consistent with the patterns proposed with pollen and charcoal records and partially also with phylogeographic information inferred from genetic data suggesting that the most suitable areas for c sativa were extended significantly during the mid holocene but declined afterwards and lost connectivity the projected patterns were compatible with existing palaeobotanical records of c sativa and provide a spatially explicit picture of the species past distribution

the 1890 surge end moraine at eyjabakkajokull iceland a re assessment of a classic glaciotectonic locality abstract the glaciotectonic architecture and sequential evolution of the eyjabakkajokull 1890 surge end moraines in iceland were studied for understanding better the formation and evolution of glaciotectonic end moraines and their relation to glacier dynamics based on morphological geological and geophysical data from terrain cross profiles cross sections and ground penetrating radar profiles we demonstrate that three different qualitative and conceptual models are required to explain the genesis of the eyjabakkajokull moraines firstly a narrow single crested moraine ridge at the distal end of a marginal sediment wedge formed in response to decoupling of the subglacial sediment from the bedrock and associated downglacier sediment transport secondly large lobate end moraine ridges with multiple closely spaced narrow asymmetric crests formed by proglacial piggy back thrusting thirdly a new model shows that moraine ridges with different morphologies may reflect different members of an end moraine continuum this is true for the eastern and western parts of the eyjabakkajokull moraines as they show similar morphological and structural styles which developed to different degrees the former represents an intermediate member with decollement at 4 5 m depth and 27 33 shortening through multiple open anticlines that are reflected as moderately spaced symmetric crests on the surface the latter represents an end member with decollement at about 27 m depth and 39 horizontal shortening through multiple high amplitude overturned and overthrusted anticlines appearing as broadly spaced symmetric crests we propose that the opposite end member would be a moraine of multiple symmetric wide open anticlinal crests of low amplitude our data suggest that the glacier coupled to the foreland to initiate the end moraine formation when it had surged to within 70 190 m of its terminal position this indicates a time frame of 2 6 days for the formation of the end moraines

sediments and landforms at kviarjokull southeast iceland a reappraisal of the glaciated valley landsystem abstract eyles identified kviarjokull an outlet of the icecap oraefajokull southeast iceland as an exemplar of the glaciated valley landsystem emphasising rockfall debris supply passive transport and reworking of a thick cover of supraglacial morainic till in this paper we take a fresh look at the sediments and landforms of kviarjokull focusing on clast form analysis to reconstruct primary transport pathways new data demonstrate the importance of active transport of debris derived from the glacier bed substantial portions of the supraglacial debris cover can be traced back to englacial channel fill deposits or anomalously thick exposures of basal ice these two types of sediments also make up much of kviarjokull s large neoglacial moraine rampart we attribute the abundance of these non rockfall sediments to the presence of a terminal overdeepening and the switch from predominantly subglacial to predominantly englacial drainage that this induces this hydrological switch enhances retention of debris within ice transport preventing it from being washed away and making it available to feed ice marginal moraine formation the complexity of sediment transport processes observed at kviarjokull and the contrast between it and alpine glaciers undermines any single concept of the glaciated valley landsystem accordingly we propose kviarjokull as the type example of a distinct subclass defined by its moderate relief high debris turnover and drainage behaviour characteristic of an overdeepened basin

de icing progression of ice cored moraines in a humid subpolar climate kotlujokull iceland modes and rates of de icing ice cored moraines under humid subpolar conditions have been determ ined for two dead ice fields of different age representing a mature and a final stage of collapse in the kotlujokull terminus region south iceland the melting processes considered are backwasting defined as the lateral retreat of near vertical ice walls or steep ice cored slopes and downwasting defined as the thinning of the ice core by melting along the top and bottom surfaces in the mature stage of collapse where there is less than 1 m of sediment cover major faces of ice exposed for rapid melting are ordinarily significant and long lived due to intense precipitation in this fully ice cored terrain the predominating processes are backwasting of exposed ice walls and downwasting by bottom melt each contributing to the annual surface lowering of about 0 5 m or 35 the total annual surface lowering melt rate due to all processes averages 1 4 m in those parts of the fully ice cored dead ice field