behaviour and process in the formation of the north european acheulean record towards a unified palaeolithic landscape approach the acheulean record of northern france and southern britain has long been acknowledged as internationally important having played an important historical role in the development of the discipline abundant artefacts have been recovered primarily from fluvial gravel archives allowing the responses of middle pleistocene human populations on the edge of their geographical distribution to be interrogated the richness of the record from such deposits can most simply be read as reflecting absolute population numbers and changes in this over time however factors such as regional super abundance of high quality flint related to solid geology and intensity of aggregate exploitation also played their part in generating the apparently regionally dense record of finds this paper investigates the inter related patterns of human behaviour preservation artefact release and research tradition which underpin these basic distribution maps we here present a framework for understanding the processes which have created the current distribution map in terms of where we find material and which periods are best represented within it we term this the unified palaeolithic landscape approach and outline ways in which the spatial and temporal range of the acheulean record can be addressed through the archaeological record of its heartland

mapping the human record in the british early palaeolithic evidence from the solent river system the lithic record from the solent river and its tributaries is re examined in the light of recent interpretations about the changing demography of britain during the lower and early middle palaeolithic existing models of the terrace stratigraphies in the solent and its tributary areas are reviewed and the corresponding archaeological record specifically handaxes for each terrace is assessed to provide models for the relative changes in human occupation through time the bournemouth area is studied in detail to examine the effects of quarrying and urbanisation on collection history and on the biases it introduces to the record in addition the effects of reworking of artefacts from higher into lower terraces are assessed and shown to be a significant problem although there is very little absolute dating available for the solent area a cautious interpretation of the results from these analyses would suggest a pre marine isotope stage mis 12 date for the first appearance of humans a peak in population between mis 12 and 10 and a decline in population during mis 9 and 8 owing to poor contextual data and small sample sizes it is not clear when levallois technology was introduced this record is compared and contrasted to that from the thames valley it is suggested that changes in the palaeogeography of britain in particular land connections to the continent might have contributed to differences in the archaeological records from the solent and thames regions copyright 2009 john wiley sons ltd

permafrost active layer abstract this article discusses the properties and occurrence of an active layer al in the near surface of the lithosphere in glacial and periglacial environments this layer shows a seasonal variability in temperature as a result of the climate the al as classically understood seasonally thaws and freezes while in glacial environments it usually only reaches 0 c the definition of al is currently not consistent with the definition of permafrost even though both concepts usually appear linked for these terms to be comparable both should be defined based on temperature variability and not exclusively on phase change thus the al would be described not only as the upper section of perennially frozen ground presenting seasonal thaw freeze cycles 1 but as a layer presenting a seasonal variation in temperature 2 classical active layer can be thawed to a depth of approximately 2 8 cm the thickest al reaches over 20 m in the particularly favorable conditions al might be completely absent with the permafrost beginning at the ground surface in glacial and sub marine permafrost environments the al includes a layer of liquid water that seasonally accompanies the permafrost glaciers and ice sheets are usually devoid of the classical al in both cases the al is usually horizontal but in specific terrains such as sea shore cliffs or karst environments the al may have a vertical course and may even be reversed both al and permafrost are common in other frozen bodies in the solar system differing mainly in their thermal character

book reviewthe techniques of modern structural geology vol 1 strain analysis j g ramsay and m i huber academic press london 1983 xiii 307 pp us 55 00 28 00 hardcover

recent advances in the understanding of quaternary periglacial features of the english channel coastlands recent advances in the understanding of quaternary periglaciation of the english channel coastlands concern laboratory modelling of periglacial processes dating of periglacial sediments and the distribution of permafrost during marine oxygen isotope stage mois 2 modelling studies have successfully simulated i ice segregation in chalk in artificial permafrost ii periglacial solifluction of natural slope sediments and iii soft sediment deformation during thaw of ice rich soil the resultant structures and deposits in these experiments have similarities with naturally brecciated chalk solifluction deposits and involutions respectively along the english channel coastlands providing insights into their genesis and palaeoenvironmental significance dating of periglacial sediments is based on radiocarbon assays of organic material in head deposits luminescence measurements of loess and coversand and mammalian biostratigraphy in raised beach and associated slope deposits most age estimates fall within mois 2 although some are within mois 6 and possibly other cold stages maps reconstructing the distribution of permafrost during mois 2 vary in detail the precise distribution of permafrost remains to be established owing to problems of i imprecise dating in the context of climatic instability ii uncertain palaeoclimatic significance of particular periglacial structures and iii sparse data on the age and distribution of relict periglacial features the wider significance of periglacial processes to the evolution of the channel coastlands is speculated to involve rapid valley development by flowing water in areas of moist frost susceptible bedrock that has been brecciated by ice segregation copyright 2003 john wiley sons ltd

influence of air temperature on a glacier s active layer temperature seasonal temperature variations occur in the glacier layer about 15 20 m below the surface while at greater depths the glacier temperature depends on the long term surface conditions it is generally accepted that for glaciers without surface melting the temperature at 10 m depth t10 i s close to the mean annual air temperature at standard screen level ta i e t10 ta we found that this relationship is not valid for ta above 178c and below 558c the goal of our investigation is to find a better temperature transfer function ttf between ta and temperature at the boundary of the active layer in accumulation areas of polar and tropical glaciers low precision t10 temperatures from boreholes obtained at 41 sites are compared with air temperatures ta measured in the vicinity of these sites for at least a 1 year period we determine that when ta falls into the temperature range 60 to 78c empirical values can be approximated as t10 1 2ta 6 7 analysis of these data suggests that high t10 occurs in the areas of the glacier that collect meltwater

atmospheric warming threatens the untapped glacial archive of ortles mountain south tyrol ortles mountain 3905 m a s l south tyrol italy is the highest mountain of the eastern european alps and its upper glacier alto dell ortles presents a unique opportunity to obtain the first paleoenvironmental record from an ice core in this area to study the suitability of this glacier as a drilling site in 2009 we performed the first preliminary study of its glaciological characteristics at 3830 m a s l the maximum thickness is 75 m and lamination of the exposed ice layers is excellent down to bedrock firn and ice lenses were observed in a 10 m shallow core and the firn ice transition was below 24 m the seasonal chemical signal is clearly preserved only within the uppermost 2008 and 2009 snow firn a simple mass balance model the incipient smoothing of the chemical record and the observed ice lenses provide evidence that melting infiltration and refreezing cycles occurred within the firn layers formed before 2008 nevertheless the mass balance of the upper part of alto dell ortles was positive 800 mm a 1 during the last few years we suggest that an environmental history is likely to be well preserved only within the ice layers formed before 1980 when summer air temperature was 28c colder than today in this area clearly the continued warming trend predicted to occur over the next few decades and the consequent increase in frequency and or intensity of infiltration processes will endanger the preservation of the glacial archive conserved in the deep ice layers of ortles mountain

strain analysis in jurassic argillites of the monte sirino area lagonegro zone southern apennines italy and implications for deformation paths in pelitic rocks analysis of strain in jurassic argillites forming part of the folded and thrusted sedimentary succession of the lagonegro basin southern italian apennines has been carried out using ellipsoid shaped reduction spots as strain markers most of the determined finite strain ellipsoids are of oblate type and show a peculiar distribution of the maximum extension direction x with maxima either subparallel or subperpendicular to the local fold axes using the strain matrix method two different deformation histories have been considered to assist the interpretation of the observed finite strain pattern a first deformation history involved vertical compaction followed by horizontal shortening occurring by a combination of true tectonic strain and volume loss whereby all strain is coaxial and there is no change in the intermediate axis of the strain ellipsoid by this type of deformation sequence which produces a deformation path where total strain moves from the oblate to the prolate strain field and back to the oblate field prolate strain ellipsoids can be generated and may be recorded where tectonic deformation has not been large enough to reverse pretectonic compaction this type of deformation history may be of local importance within the study area i e it may characterize some fold hinge regions and more generally is probably of limited occurrence in deformed pelitic rocks a second deformation sequence considered the superposition of pre tectonic compaction and tectonic strain consisting of initial layer parallel shortening followed by layer parallel shear related to flexural folding also in this instance volume change during tectonic deformation and tectonic plane strain have been assumed for geologically reasonable amounts of volume loss due to compaction and of initial layer parallel shortening this type of deformation history is capable of producing a deformation path entirely lying within the oblate strain field but still characterized by a changeover during deformation of the maximum extension axis x from a position parallel to the fold axis to one perpendicular to it this type of deformation sequence may explain the main strain features observed in the study area where most of the measured finite strain ellipsoids determined from the limb regions of flexural folds display an oblate shape irrespective of the orientation of their maximum extension direction x with respect to the local structural trends more generally this type of deformation history provides a mechanism to account for the predominance of oblate strains in deformed pelitic rocks

the kinematics of break thrust folds abstract the kinematics of asymmetric open to close often overturned thrust related folds are commonly explained with fault propagation or detachment fold models field observations of thrust related folds exposed in tennessee virginia wyoming and montana that exhibit this geometry indicate that models of fault propagation and detachment folds do not adequately describe the kinematics of these structures existing models of fault propagation and detachment folding employ migrating kink shaped hinges and relate fold geometry entirely to fault geometry slip and to the thickness of the basal detachment layers the models exclude the relation between fold shape and amplitude and they do not predict a correlation between competent layer thickness and fold wavelength as expected from buckling theory thrust related folds examined in this study exhibit unique distributions of fabrics in the hinges and forelimbs which demonstrate a lack of hinge migration furthermore the ratios of dominant member thickness to fold wavelenght agree with those expected for folds controlled by a single layer and they are within the expected range for folds with multiple evenly spaced harmonically deforming layers our analyses suggest these folds evolved from an initial brief stage of sinusoidal buckling to a later stage of fixed hinge kinking and thrusting thrust related folds which exhibit a geometry and mesofabric distribution suggesting this type of evolution are defined as break thrust folds

volume loss during cleavage formation in the meguma group nova scotia canada abstract diffusive mass transfer pressure solution is a widely recognized cleavage forming mechanism under low grade conditions the amount of accompanying volume change during cleavage development however is difficult to quantify and remains controversial the distance between sites of mineral dissolution and reprecipitation and transport mechanisms also are controversial the structural history of the cambrian ordovician meguma group nova scotia canada is well known and abundant strain markers provide an opportunity to assess geometrically volume changes accompanying cleavage development during diagenesis about 70 compaction in muds and 15 in silts and sands occurred the pelitic to psammitic meguma group was cleaved prior to being folded pressure solution was the dominant cleavage forming deformation mechanism under chlorite grade metamorphic conditions during the early devonian acadian orogeny measurement of tectonic strain in principal directions x y z shows that bedding parallel coaxial shortening z is 60 and there is no evidence of fold hinge parallel extension y estimation of tectonic vertical extension x in the cleavage plane is complicated by diagenetic compaction corrections to primary strain markers but is insufficient to compensate for the observed 60 shortening in z indicating 40 60 volume loss during cleavage formation because cleavage formed at least 50 ma after deposition and under approximately 6 km of silurian to early devonian strata porosity of the sediments upon onset of cleavage was likely less than 15 pore space reduction therefore cannot account for the apparent volume loss during cleavage formation cleavage related volume loss applies regionally and to a stratigraphic thickness of several thousand meters implying that a large amount of material was removed and transported large distances when combined with 50 shortening by folding a bulk tectonic shortening of 80 is estimated for the meguma group during the acadian orogeny

growth processes and melange formation in the southern apennines accretionary wedge abstract the southern apennines owe their present geometry to the subduction of an apulian continental lithospheric slab and are thus best interpreted as an accretionary wedge southward the apenninic thrust front branches on to the still active ionian wedge which is related to the present calabro sicilian subduction the interpretation of conventional seismic reflection profiles and exploration wells combined with geologic field studies biostratigraphy and structural geology provide constraints for a geodynamic model for the post messinian growth of the apenninic prism our model for the apennines is a good analogy for submerged oceanic accretionary prisms in both instances features such as out of sequence thrusts underplating and duplexes are viewed as processes to explain the thickening of accretionary wedges syntectonic terrigenous deposits have accumulated in the synclines developed above the flats of pliocene thrust faults these depocenters represent piggy back basins younger accretion at the eastern border of the accretionary wedge has led to a progressive uplifting and tilting of the already emplaced thrust sheets including a continous westward migration of the depocenters in the piggy back basins during pliocene and early quaternary times a contrary west to east migration of the depocenters locally occurred where preexisting flats of pliocene thrust faults have been refolded rather than only being rotated dewatering processes and effects of overpressures on undercompacted sediment deformations can also be studied in the southern apennines melanges and broken formations form an important component of the trench apparently restricted to the base of tectonic nappes listric normal faults are a major structural element which preserves in combination with the erosion of topographic highs and resedimentation in the piggy back basins a uniform geometric shape critical taper for the prism the age and location of these distensive or gravitational effects are also discussed

on the thermal regime of an arctic valley glacier a study of white glacier axel heiberg island n w t canada from 1974 to 1981 a total of 32 bore holes was drilled on white glacier and vertical ice temperature profiles measured the data obtained allowed the construction of three longitudinal and four transverse profiles of the two dimensional temperature distributions thus an extensive layer of temperate or near temperate ice was discovered close to the bedrock in the lowest part of the glacier tongue it was also found that the temperature distribution cannot be in a steady state since there is a temperature minimum 100 150 m below the glacier surface in the accumulation area a simple numerical model calculation shows that this minimum can be mostly explained by the general climatic warming since 1880 the 10 m temperatures show diffuse relations to climatic conditions and balance zones a simple scheme for extrapolating surface temperatures is discussed

strain variations and three dimensional strain factorization at the transition from the southern to the central appalachians abstract the transition between the southern and the central appalachian foreland thrust system is a region subjected to at least two non coaxial deformations where typical two dimensional analyses such as cross section balancing or plane strain retro deformation cannot be applied three dimensional factorization can simulate the non coaxial strain history simulation results for compaction and layer parallel shortening lps were compared to finite strains of 16 quartz arenite samples from the tuscarora sandstone successful simulations indicate in the southern appalachians 30 35 total compaction by volume loss including a 4 5 9 e w horizontal shortening during lithification and 5 lps along 150 330 by plane strain or axial symmetric flattening in the central appalachians 30 35 total compaction by volume loss including a 3 7 n s horizontal shortening during lithification and 10 lps along 120 300 by plane strain or axial symmetric flattening in the transition zone 30 compaction by volume loss including a 3 e w horizontal shortening during lithification 5 southern lps along 150 330 by axial symmetric flattening and 5 10 central shortening along 130 or 140 by plane strain or axial symmetric flattening at 10 to the normal central trend from the simulations horizontal shortening in the southern appalachians during lithification in the mississippian was greater than the later alleghanian deformation this shortening probably represents a very early lps developed in unlithified sand that required less deviatoric stress to deform than did the cemented quartz arenites during later tectonic deformation also the oblique and weaker central tectonic lps in the transition zone probably represents behavior at the limits of central appalachian deformation finally the lps simulations indicate that axial symmetric flattening oblate strain is more successful than plane strain as the representative behavior so caution is recommended in assuming plane strain as the dominant strain behavior in orogenic forelands

pleistocene fluvial terraces from northern france seine yonne somme synthesis and new results from interglacial deposits the seine yonne and somme are the main rivers draining northwestern france and flowing into the channel during pleistocene cold stages they were tributaries of the fleuve manche they are characterised by well developed stepped terrace systems showing up to 10 incision steps for the last 1 ma after 15 years of research and the synthesis of stratigraphical sedimentological bioclimatical data and numerical dating these terrace systems are interpreted as the response of the fluvial environments to climatic cyclicity superimposed on a background of slow tectonic uplift the comparison of these three terrace systems shows that the incision budget is similar within the studied area about 55 65 m 1 ma implying relative homogeneity of uplift in the main part of the area beyond marine influence the analysis of each stepped alluvial formation shows regular sediment balance generally composed of coarse periglacial gravels pleniglacial covered by fine grained sediments locally overlain by calcareous tufa interglacial however in the lower seine valley close to the present coast the low terrace includes two estuarine interglacial units interbedded within periglacial gravel units nevertheless until recently evidence of full interglacial conditions remained elusive in fluvial contexts especially in the somme to address these issues a new research programme has been launched on tufa deposits that are the best candidate to register the climatic optimum initial results from la celle seine saint acheul and caours somme allow palaeoenvironmental reconstructions of mis 11 and 5e and thus confirm the importance of calcareous tufa to define a reference record of pleistocene interglacials for northern france moreover it has been previously demonstrated that the main incision leading to terrace formation can be attributed to the transition between interglacial and glacial during early glacial phases the new results from interglacial records have important implications concerning the precise occurrence of the major incision phases within the climatic cycle as they provide the starting point immediately preceding downcutting

strains and folds within thrust sheets an analysis of the heilam sheet northwest scotland abstract the changes of shape and orientation of fossil worm burrows have been used to carry out a detailed strain analysis of the heilam thrust sheet in the moine thrust zone northwest scotland the strains have been factorised into components of layer parallel shear 1 layer normal shear 2 and layer parallel shortening or elongation variations in the 1 shear are largely lithologically controlled some strain is due to flexural processes as the thrusts and overlying beds change dip over thrust ramps or are tightened by later deformation while there may also be a component of drag which increases towards the overlying thrust this predating the shear due to flexure a contoured map of the values suggests that major folds within the thrust sheet developed as a result of stick or drag on the floor thrust prior to ramp climb this led to differential movement in the transport direction causing layer parallel shortening accompanied or followed by buckling of the layers a map showing layer normal shear strains 2 suggests that the heilam sheet forms a major surge zone the central part having moved further wnw than the northern and southern parts this has led to components of lateral shear along parts of the sheet especially in the north producing curvature of the imbricate faults

a 25 000 year tropical climate history from bolivian ice cores ice cores that were recovered from the summit of sajama mountain in bolivia provide carbon 14 dated tropical records and extend to the late glacial stage lgs oxygen isotopic ratios of the ice decreased 5 4 per mil between the early holocene and the last glacial maximum which is consistent with values from other ice cores the abrupt onset and termination of a younger dryas type event suggest atmospheric processes as the probable drivers regional accumulation increased during the lgs during deglaciation and over the past 3000 years which is concurrent with higher water levels in regional paleolakes unlike polar cores sajama glacial ice contains eight times less dust than the holocene ice which reflects wetter conditions and extensive snow cover

the liguride complex of southern italy a cretaceous to paleogene accretionary wedge abstract the ophiolite bearing allochthonous flysch liguride complex of the southern apennines italy has traditionally been divided into two tectonic units the metamorphic frido unit and the unmetamorphosed cilento unit the two units have hitherto been considered to derive from two distinct paleogeographic domains however the identification of cilento unit sediments within frido unit successions implies that the sediments of both units were coeval deposits within the same sedimentary basin cilento unit sediments also occur as the sedimentary cover of kilometre scale oceanic slices within the liguride complex indicating deposition on oceanic basement and not continental basement as was previously considered thrust transport directions and sediment provenance indicate that during late jurassic time this ocean basin lay to the east of the calabrian terrain and to the west of apulia calabria and apulia representing the european and african margins of neotethys respectively northwestwards subduction of oceanic crust beneath the calabrian terrain from late cretaceous time onwards produced an accretionary wedge which was later emplaced onto the apulian margin during the burdigalian collision of calabria and apulia the liguride complex represents the obducted remains of this accretionary wedge this interpretation contains three important implications for pre tertiary plate tectonic reconstructions of the western mediterranean region these are 1 1 the calabrian continental terrain formed part of the iberian plate on the north margin of neotethys this may have implications for the former location and continuation of the north pyrenean fault 2 2 the existence of a continuation of the eo alpine belt through calabria and the kabylies is placed in doubt thus requiring only one constant polarity nw dipping subduction direction to explain the structures now seen in these regions 3 3 the existence of a transform fault between the europe vergent structures of corsica and the africa vergent structures of calabria this transform must have been active from at least late cretaceous time in a position now occupied by the tyrrhenian sea

cold firn and ice of high altitude glaciers in the alps measurements and distribution modelling the thermal regime of high altitude accumulation areas in the swiss alps was systematically investigated on the jungfraufirn bernese alps on the breithornplateau valais alps and on grenzgletscher valais alps in 1991 1992 and 1994 temperatures were measured in a deep hole 120 m deep and in several shallow holes 14 30 m deep whereas the wide neve of the jungfraufirn at 3400 3600 m a s l and the 3800 m high breithorn plateau seems to be predominantly temperate cold firn and ice temperatures were measured throughout on grenzgletscher 3900 4450 m a s l mean firn temperatures on grenzgletscher vary strongly and range between 3 and 14 c a comparison between the measured temperature profiles and a one dimensional heat conduction calculation shows that the release of latent heat by penetrating and refreezing meltwater decisively influences the thermal pattern of the firn pack a multiple linear regression model based on measured firn temperatures from the european alps and the parameters altitude and aspect yields aspect dependent lower boundaries for the occurrence of cold firn ranging between 3400 northerly aspects and 4150 m a s l southerly aspects a total of 120 glaciers with cold firn areas are found when applying the model to glacier inventory data from the european alps

importance of basal boundary conditions in transient simulations case study of a surging marine terminating glacier on austfonna svalbard we assess the importance of basal boundary conditions for transient simulations of basin 3 austfonna ice cap between january 1995 and december 2011 and for the surge starting in 2012 by carrying out simulations with the full stokes model elmer ice and the vertically integrated model bisicles time varying surface mass balance data from the regional climate model hirham5 are downscaled according to elevation basal friction coefficient is varied through time by interpolating between two data constrained inversions of surface velocity fields from 1995 and 2011 evolution of the basal boundary condition appears to be much more important for mass discharge and the dynamic response of the fast flowing unit in basin 3 than either model choice or the downscaling method for the surface mass balance in addition temporally linear extrapolation of the evolution of basal friction coefficient beyond the 2011 distribution could not reproduce the expansion of the acceleration observed in southern basin 3 between january 2012 and june 2013 this implies that changes in basal friction patterns and in turn basal processes that are not currently represented in either model are among the most important factors for the 2012 acceleration

first geophysical and shallow ice core investigation of the kazbek plateau glacier caucasus mountains first ever ice core drilling at mt kazbek caucasus mountains took place in the summer of 2014 a shallow ice core 18 m was extracted from a plateau at 4500 m a s l in the vicinity of the mt kazbek summit 5033 m a s l a detailed radar survey showed that the maximum ice thickness at this location is 250 m borehole temperature of 7 c was measured at 10 m depth the ice core was analyzed for oxygen and deuterium isotopes and dust concentration from the observed seasonal cycle it was determined that the ice core covers the time interval of 2009 2014 with a mean annual snow accumulation rate of 1800 mm w eq multiple melt layers have been detected 18o values vary from 25 to 5 the dust content was determined using a particle sizing and counting analyzer the dust layers were investigated using scanning electron microscopy and x ray diffraction analysis dust can be separated into two categories by its origin local and distant samples reflecting predominantly local origin consisted mainly of magmatic rocks while clay minerals were a characteristic of dust carried over large distances from the deserts of the middle east and sahara the calculated average dust flux over three years at kazbek was of 1 3 mg cm2 a 1 neither 18o nor dust records appear to have been affected by summer melting overall the conditions on kazbek plateau and the available data suggest that the area offers good prospects of future deep drilling in order to obtain a unique environmental record

an englacial hydrologic system of brine within a cold glacier blood falls mcmurdo dry valleys antarctica taylor glacier hosts an active englacial hydrologic system that feeds blood falls a supraglacial outflow of iron rich subglacial brine at the terminus despite mean annual air temperatures of 17 c and limited surface melt taylor glacier is an outlet glacier of the east antarctic ice sheet that terminates in lake bonney mcmurdo dry valleys to image and map the brine feeding blood falls we used radio echo sounding to delineate a subhorizontal zone of englacial brine upstream from blood falls and elongated in the ice flow direction we estimate volumetric brine content in excess of 13 within 2 m of the central axis of this zone and likely much higher at its center brine content decreases but remains detectable up to 45 m away along some transects hence we infer a network of subparallel basal crevasses allowing injection of pressurized subglacial brine into the ice subglacial brine is routed towards blood falls by hydraulic potential gradients associated with deeply incised supraglacial valleys the brine remains liquid within the subglacial and englacial environments through latent heat of freezing coupled with elevated salt content our findings suggest that cold glaciers could support freshwater hydrologic systems through localized warming by latent heat alone

dating the earliest human occupation of western europe new evidence from the fluvial terrace system of the somme basin northern france abstract dating the earliest human occupation of western europe and reconstructing its relations with climatic and environmental constrains is becoming a central question especially with the discovery of palaeolithic artefacts allocated to the early pleistocene in south east britain and in central france in this context the quaternary sequences of the somme basin where is located the type site of the acheulean is a key area research undertaken for more than 20 years on both fluvial and loess sequences of the somme basin provide a unique dataset for the study of the relations between human occupations and environmental variations studies have been based on an interdisciplinary approach combining sedimentology palaeontology and geochronology u series esr and esr u series meanwhile the palaeoenvironmental interpretation of pleistocene sequences containing palaeolithic levels has been refined with biological proxies and sedimentological data obtained on both loess and fluvial sequences our data have highlighted the impact of the 100 ky cycles on terraces formation since 1 ma and the fluvial terraces system of the somme basin has become a reference model for the study of the response of fluvial systems to milankovich cycles in areas characterised by slow continuous uplift compilation of the whole results from modern archaeological excavations within this chronoclimatic reference system show that human occupation of this area has been discontinuous and highly influenced by climatic and environmental factors in the somme terraces system in situ acheulean settlements where dated to early mis 12 at 450 ka in the 1990s but new field discoveries allow to increase significantly the age of the oldest human occupation early middle pleistocene the first one amiens rue du manege 2007 is dated at 550 ka using esr and terrace stratigraphy the newest findings have been done in 2011 2013 in abbeville carriere carpentier where mammal assemblages show that calcareous fluvial deposits have been deposited in an interglacial environment on the basis of terrace stratigraphy esr quartz dating and biostratigraphic data these fluvial deposits are allocated to mis 15 handaxes discovered at the base of the slope deposits directly overlying the fluvial sequence can be as a first hypothesis allocated to mis 14 they are thus due to homo heidelbergensis according to the age of the eponymous mauer site in germany consequently in the state of knowledge the rue du manege and carriere carpentier findings represent the oldest in situ evidence of the hominid occupation in the terrace record of northern france

book review the techniques of modern structural geology volume 2 folds and fractures john g ramsay and martin i huber academic press london 1987 xi 309 398 pp price stg17 50 us 34 50 paperback

deep drilling of glaciers in eurasian arctic as a source of paleoclimatic records abstract results of the deep drilling 80 100 m of eurasian arctic glaciers svalbard severnaya zemlya and franz josef land from the middle of the 1970s to the end of the 1990s have been discussed all spectra of the techniques used for ice core and borehole studies results of ice core dating and major paleoclimatic conclusions have been analyzed particular emphasis has been placed on the problem of accuracy and comparison of dates suggested by different authors new integrated time scale for eurasian arctic glaciers based on the ice core dating of vetreniy ice cap graham bell island and franz josef land which covers the last 700 800 years has been developed methods and results of the new paleo temperature reconstructions have been analyzed

pencil structure and strain in weakly deformed mudstone and siltstone abstract weakly deformed mudstone and siltstone middle ordovician knobs formation of the appalachian valley and ridge province south western virginia u s a show strain dependent transitions between bedding fissility pencil structure and cleavage pencil structures are associated with a bulk inhomogeneous shortening deformation where minimum principal strain z ranges between 9 and 26 shortening assuming a plane strain and constant volume where strains are less bedding fissility dominates pencil fragments are defined by intersecting fracture sets subparallel to the pre existing bedding fissility and cleavage their long axes are both parallel to the bedding cleavage intersection and to the inferred y axis of the tectonic strain ellipsoid pencil development is considered to result from fracturing along both fabric anisotropies during weathering and post tectonic stress relaxation pencils show variations in size and shape depending on lithology grain size and composition degree of initial clay preferred orientation degree of cleavage development type of cleavage total bulk strain and degree of strain homogeneity their shape l w however is a direct measure of total y z strain since strain determinations from chlorite pressure fringes on framboidal pyrite within the pencil fragments give y z 0 913 0 019 l w pencil structure is therefore a potential strain marker in weakly deformed rocks

mechanisms of thrust propagation some examples and implications for the analysis of overthrust terranes abstract evidence is presented for the existence of three fundamental mechanisms by which thrust sheets move the mechanisms are 1 failure of a stiff layer to form ramp flat geometry imbricated thrust sheets 2 detachment of a layer by folding decollement thrust sheets 3 differential layer parallel shortening lps thrust sheets the mechanisms are independent but may operate interactively to form families of hybrid thrust sheets since lps thrust sheets have not been previously described or documented data from the new york plateau deformed almost exclusively by differential lps is presented to demonstrate the physical characteristics of this thrust mechanism information from the plateau indicates that finite strain behavior closely reflects the geometric boundary conditions and is independent of temperature and depth of burial finite strain data are used to construct a set of iso strain maps in both the deformed and undeformed states the iso strain maps are in turn used to determine the displacement field for the thrust sheet the displacement field allows visualization of the effects of both lagrangian and eulerian transformations on an initially orthogonal grid utilizing sections from a number of overthrust belts it is shown that the three mechanisms occur universally although in various proportions lps is regionally developed throughout the central and northern appalachians the presence of the lps thrust sheets probably accounts for the failure of structural cross sections to bed length balance in these blind thrust terranes finally a series of examples drawn from the field as well as the literature are used to illustrate both the characteristics of hybrid thrust sheet families as well as to indicate how knowledge of their behavior can be utilized in developing strategies for the construction and balancing of structural cross sections

strain paths during slaty cleavage formation the role of volume loss abstract strain analyses of slates commonly investigate the sequence of shapes that must have been superimposed to produce the observed strained state methods such as rf try to quantify the cleavage forming deformation and see through that component to examine any initial shape an alternative approach is to reverse this process by considering the variation in final shapes derived when plausible cleavage forming strain ellipsoids are superimposed on realistic initial shapes specifically a deformation involving both plane strain and volume loss may be superimposed on an initial shape formed by diagenetic flattening in this case the angle between bedding and the incipient cleavage plane is an important variable in controlling final ellipsoid shapes this approach has been adopted for a data set measured from the ordovician borrowdale volcanics in the english lake district results show that neither successive increments of plane strain without volume loss nor incremental plane strain plus volume loss adequately explain the observed pattern of final shapes one permissible solution is generated if increments of pure volume loss perpendicular to the incipient cleavage plane precedes plane strain distortion initial layer parallel shortening may therefore play an important part during cleavage development in these slates