use of terrestrial photogrammetry based on structure from motion for mass balance estimation of a small glacier in the italian alps different high resolution techniques can be employed to obtain information about the three dimensional 3d surface of glaciers this is typically carried out using efficient but also expensive and logistically demanding light detection and ranging lidar technologies such as airborne scanners and terrestrial laser scanners recent technological improvements in the field of image analysis and computer vision have prompted the development of a low cost photogrammetric approach which is referred to as structure from motion sfm combined with dense image matching algorithms this method has become competitive for the production of high quality 3d models however several issues typical of this approach should be considered for application in glacial environments in particular the surface morphology the different substrata the occurrence of sharp contrast from solar shadows and the variable distance from the camera positions can negatively affect the image texture and reduce the possibility of obtaining a reliable point cloud from the images the objective of this study is to test the structure from motion multi view stereo sfm mvs approach in a small debris covered glacier located in the eastern italian alps using a consumer grade reflex camera and the computer vision based software photoscan the quality of the 3d models produced by the sfm mvs process was assessed via the comparison with digital terrain models obtained from terrestrial laser scanning tls surveys that were performed at the same epochs the effect of different terrain gradients and different substrata debris snow and firn was also evaluated in terms of the accuracy of the reconstruction by sfm mvs versus tls our results show that the quality of this new photogrammetric approach is similar to the quality of tls and that point cloud densities are comparable or even higher compared with tls however special care should be taken while planning the sfm survey geometry to optimize the 3d model quality and spatial coverage copyright 2015 john wiley sons ltd

facies distribution and textural variation in faro drift contourites velocity fluctuation and drift growth abstract detailed study of seismic profiles piston cores and bottom photographs from the faro drift on the southern margin of portugal has led to a better understanding of drift development and its relationship to bottom current circulation data on the contourite facies characteristics and the surface microphysiography have been published elsewhere here we concentrate on sediment distribution and geometry longitudinal trends in facies types mean grain size sedimentary structures and composition can be interpreted in terms of relative intensity of currents over different parts of the drift these are generally more intense in the marginal channels and at the upstream or eastern end of the drift three different scales of vertical variation of facies can be identified at the large scale 300 500 m of sediment has accumulated over 4 6 ma in a regular vertical succession due to the northward progradation of the drift at the medium scale the upper 20 30 m of sediment shows alternating phases of active lateral progradation and uniform vertical accumulation that may correlate with episodes of more and less current activity related to high and low sea level stands respectively over the past 0 3 ma at the small scale the topmost 2 3 m of sediment deposited in approximately 0 03 ma shows three zones of coarser grained sediments separated by finer grained contourites this sequence can also be interpreted in terms of long term fluctuation in bottom current activity although the signal is clearly complex this kind of analysis of sedimentary drifts can lead to more accurate reconstruction of paleocirculation patterns

seismic geomorphological reconstructions of plio pleistocene bottom current variability at goban spur abstract high resolution single channel sparker reflection seismic data revealed the presence of large scale sediment waves nearby dsdp site 548 located on goban spur they developed in a gentle terraced environment which contrasts with the canyon incised celtic margin and the relatively smooth porcupine seabight to the north based upon the morphological characteristics of the observed seabed and buried sediment waves energetic alongslope bottom currents are thought to be the driving mechanism for the sediment wave development these currents are driven on their turn by an enhanced internal tide regime that could be attributed to the introduction of the mediterranean outflow water the dsdp site 548 downhole geophysical data and the seismic stratigraphic analysis allowed the differentiation of three sequences that relate to evolutionary stages since the lower pliocene the sequences are bounded by local erosional events associated with mass wasting events which seem to occur roughly synchronously to major northern hemisphere glaciations respectively during the lower pleistocene 2 5 to 2 15 ma and the middle pleistocene 0 45 ma the lower sequence from 4 5 to 2 15 ma shows no morphological evidence of bottom current driven sedimentation it is however settled over a smooth erosional surface which could indicate the introduction of the mediterranean outflow water the intermediate sequence is characterised by large scale sediment waves that have gradually developed in close association with palaeo seafloor irregularities it is inferred that the sedimentation resumed with a relative bottom current energy increase the youngest sequence recorded active sediment wave formation similar to the previous sequence although the goban spur sediment waves cannot be regarded as contourite drifts as such their stratigraphic evolution corresponds to other well documented contourite depositional systems influenced by the mediterranean outflow water

near bottom particle concentration and flux temporal variations observed with sediment traps and nepholometer on the meriadzek terrace bay of biscay abstract the meriadzek terrace a 2100m deep plateau on the north east atlantic continental slope was chosen as the experimental site for a multidisciplinary programme to observe the parameters needed for a better understanding of biological processes in the benthic environment two approaches were used to study the input of particulate matter to the bathyal seabed sediment traps and indirect particle concentration measurements with nephelometry these two technologies do not measure particles of the same size range but as we are interested in the fluctuations of the particle supply their results are complementary vertical profiles of nephelometry show that over the meriadzek terrace there is 125m thick nepheloid layer immediately above the bottom the dynamics in the deep layer has been determined by measurements made with a module autonome pluridisciplinaire map an in situ monitoring device developed at ifremer which measures currents nephelometry temperature vertical profile near the bottom throughout six months of measurements in 1984 the currents at 0 5m and 120m above the bottom were subject to semi diurnal tidal oscillations the intensity of light scattering recorded with the nephelometer on the map was highly correlated with current velocities especially with semidiurnal tidal oscillations which seem to induce local resuspension there are also longer term fluctuations notably a very strong event which lasted several days during august this event lagged behind a period of high intensity of internal waves correlated with a reversal in current direction the sediment trap pieges a particules pap observations showed that the particle fluxes on the meriadzek terrace have a cycle of variation similar to primary production which is characterized by a maximum in may during the phytoplankton bloom and a minimum during january there was also interannual fluctuation these two kinds of results point out the different time scales from some hours to several months of the large temporal fluctuations which affect the near bottom particle behaviour

neogene stratigraphy and the sedimentary and oceanographic development of the nw european atlantic margin a regional correlation of neogene stratigraphy has been attempted along and across the nw european atlantic continental margin between mid norway and sw ireland two unconformity bounded successions are recognised these are referred to as the lower and upper neogene successions and have been dated as miocene early pliocene and early pliocene holocene respectively in age their development is interpreted to reflect plate wide tectonically driven changes in the sedimentary oceanographic and latterly climatic evolution of the ne atlantic region the lower neogene succession mainly preserves a record of deep water sedimentation that indicates an expansion of contourite sediment drifts above submarine unconformities within this succession on both sides of the eastern greenland scotland ridge from the mid miocene this is interpreted to record enhanced deep water exchange through the faroe conduit deepest part of the southern gateway and can be linked to compressive inversion of the wyville thomson ridge complex thus a pervasive interconnected arctic north atlantic deep water circulation system is a neogene phenomenon the upper neogene succession records a regional change at about 4 ma in the patterns of contourite sedimentation submarine erosion new depocentres coeval with the onset of rapid seaward progradation of the continental margin by up to 100 km this build out of the shelf and slope is inferred to record a marked increase in sediment supply in response to uplift and tilting of the continental margin associated changes in deep water circulation may be part of an atlantic wide reorganisation of ocean bottom currents glacial sediments form a major component of the prograding shelf margin shelf slope sediment wedges but stratigraphic data indicate that the onset of progradation pre dates significant high latitude glaciation by at least 1 ma and expansive northern hemisphere glaciation by at least 3 ma

age constraints on the origin and growth history of a deep water coral mound in the northeast atlantic drilled during integrated ocean drilling program expedition 307 sr isotope stratigraphy provides a new age model for the first complete section drilled through a deep water coral mound the 155 m long section from challenger mound in the porcupine sea bight southwest of ireland is on miocene siliciclastics and consists entirely of sediments bearing well preserved cold water coral lophelia pertusa the 87sr 86sr values of 28 coral specimens from the mound show an upward increasing trend correspond to ages from 2 6 to 0 5 ma and identify a significant hiatus from ca 1 7 to 1 0 ma at 23 6 m below seafloor the age of the basal mound sediments coincides with the intensification of northern hemisphere glaciations that set up the modern stratification of the northeast atlantic and enabled coral growth mound growth persisted throughout glacial interglacial fluctuations reached a maximum rate 24 cm k y ca 2 0 ma and ceased at 1 7 ma unlike other buried mounds in porcupine seabight challenger mound was only partly covered during its growth interruption and growth restarted ca 1 0 ma

looking for clues to paleoceanographic imprints a diagnosis of the gulf of cadiz contourite depositional systems a new morphosedimentary map of the gulf of cadiz is presented showing the contourite depositional system on the gulf s middle slope this map is constructed from a broad da tabase provided by the spanish research council and the u s naval research laboratory our map shows that this contourite depositional system comprises five morphosedimentary sectors 1 proximal scour and sand ribbons 2 overflow sedimentary lobe 3 channels and ridges 4 contourite deposition and 5 submarine canyons the gulf of cadiz con tourite depositional system stems directly from the interaction between mediterranean out flow water and the seafloor its morphosedimentary sectors are clearly related to the sys tematic deceleration of the mediterranean outflow waters westward branches bathymetric stress on the margin and the coriolis force the slope s depositional system can be consid ered as a mixed contourite and turbidite system i e a detached combined drift and fan

terrestrial sfm mvs photogrammetry from smartphone sensors abstract smartphones can be regarded as cameras natively equipped with geolocation and orientation sensors making them powerful portable user friendly and inexpensive tools for terrestrial structure from motion multiview stereo photogrammetry sfm mvs surveys camera extrinsic parameters i e camera position and orientation required to produce fully georeferenced sfm mvs 3d models are available for the majority of smartphone images via inbuilt magnetometer accelerometer gyroscope and global navigation satellite system gnss sensors the precision of these internal sensors is not yet sufficient to directly use them as input to sfm mvs photogrammetric reconstructions however when the reconstructed scene is significantly greater than the positional error camera extrinsic parameters can be successfully used to register 3d models during post processing we present a survey of a 400 m wide vertical cliff to illustrate a workflow that enables the use of smartphone cameras to generate and fully georeference photogrammetric models without employing ground control points survey images were acquired at a distance of 350 m to the mapped scene using a consumer grade smartphone this survey image dataset was subsequently used to build an unreferenced 3d model which was registered during post processing using orientation and position metadata tagged to each photograph

an advanced photogrammetric method to measure surface roughness application to volcanic terrains in the piton de la fournaise reunion island abstract we present a rapid in situ photogrammetric method to characterize surface roughness by taking overlapping photographs of a scene the method uses a single digital camera to create a high resolution digital terrain model pixel size of 1 32 mm by means of a free open source stereovision software it is based on an auto calibration process which calculates the 3d geometry of the images and an efficient multi image correlation algorithm the method is successfully applied to four different volcanic surfaces namely a a lava flows pahoehoe lava flows slabby pahoehoe lava flows and lapilli deposits these surfaces were sampled in the piton de la fournaise volcano reunion island in october 2011 and displayed various terrain roughnesses our in situ measurements allow deriving digital terrain models that reproduce the millimeter scale height variations of the surfaces over about 12 m 2 five parameters characterizing surface topography are derived along unidirectional profiles the root mean square height the correlation length l c the ratio z s 2 l c the tortuosity index and the fractal dimension d anisotropy in the surface roughness has been first investigated using 1 m long profiles circularly arranged around a central point the results show that l c z s and d effectively catch preferential directions in the structure of bare surfaces secondly we studied the variation of these parameters as a function of the profile length by drawing random profiles from 1 to 12 m in length we verified that and l c increase with the profile length and therefore are not appropriate to characterize surface roughness variation we conclude that z s and d are better suited to extract roughness information for multiple eruptive terrains with complex surface texture

impact of restriction of the atlantic mediterranean gateway on the mediterranean outflow water and eastern atlantic circulation during the messinian 1 messinian foraminiferal stable oxygen and carbon isotopes of the montemayor 1 core guadalquivir basin sw spain have been investigated this record is exceptional to study the mediterranean outflow water mow impact on the atlantic meridional overturning circulation amoc and global climate during the messinian because the core is near the guadalhorce corridor the last betic gateway to be closed during the early messinian our results allow dating accurately its closure at 6 18 ma constant benthic 18o values high difference between benthic and planktonic 18o and low sedimentation rates before 6 18 ma indicate the presence of a two layer water column with bottom winnowing due to an enhanced mediterranean outflow current the enhanced contribution of dense mow to the north atlantic ocean likely fostered the formation of north atlantic deep water nadw after 6 18 ma benthic 18o values parallel that of the global glacioeustatic curve the difference between benthic and planktonic 18o is low and sedimentation rates considerably increased this indicates a good vertical mixing of the water column interruption of the mow and a dominant glacioeustatic control on the isotopic signatures according to the role of mow in the modern atlantic thermohaline circulation the reduction of the mow after the closure of the guadalhorce corridor might have resulted in a decreased nadw formation rate between 6 0 and 5 5 ma weakening the amoc and promoting northern hemisphere cooling after the gibraltar strait opening the restoration of the mow and related salt export from the mediterranean could have promoted an enhanced nadw formation

influence of the atlantic inflow and mediterranean outflow currents on late quaternary sedimentary facies of the gulf of cadiz continental margin abstract the late quaternary pattern of sedimentary facies on the spanish gulf of cadiz continental shelf results from an interaction between a number of controlling factors that are dominated by the atlantic inflow currents flowing southeastward across the cadiz shelf toward the strait of gibraltar an inner shelf shoreface sand facies formed by shoaling waves is modified by the inflow currents to form a belt of sand dunes at 10 20 m that extends deeper and obliquely down paleo valleys as a result of southward down valley flow a mid shelf holocene mud facies progrades offshore from river mouth sources but atlantic inflow currents cause extensive progradation along shelf toward the southeast increased inflow current speeds near the strait of gibraltar and the strong mediterranean outflow currents there result in lack of mud deposition and development of a reworked transgressive sand dune facies across the entire southernmost shelf at the outer shelf edge and underlying the mid shelf mud and inner shelf sand facies is a late pleistocene to holocene transgressive sand sheet formed by the eustatic shoreline advance the late quaternary pattern of contourite deposits on the spanish gulf of cadiz continental slope results from an interaction between linear diapiric ridges that are oblique to slope contours and the mediterranean outflow current flowing northwestward parallel to the slope contours and down valleys between the ridges coincident with the northwestward decrease in outflow current speeds from the strait there is the following northwestward gradation of contourite sediment facies 1 upper slope sand to silt bed facies 2 sand dune facies on the upstream mid slope terrace 3 large mud wave facies on the lower slope 4 sediment drift facies banked against the diapiric ridges and 5 valley facies between the ridges the southeastern sediment drift facies closest to gibraltar contains medium fine sand beds interbedded with mud the adjacent valley floor facies is composed of gravelly shelly coarse to medium sand lags and large sand dunes on the valley margins by comparison the northwestern drift contains coarse silt interbeds and the adjacent valley floors exhibit small to medium sand dunes of fine sand because of the complex pattern of contour parallel and valley perpendicular flow paths of the mediterranean outflow current the larger scale bedforms and coarser grained sediment of valley facies trend perpendicular to the smaller scale bedforms and finer grained contourite deposits of adjacent sediment drift facies radiocarbon ages verify that the inner shelf shoreface sand facies sedimentation rate 7 1 cm kyr mid shelf mud facies maximum rate 234 cm kyr and surface sandy contourite layer of 0 2 1 2 m thickness on the cadiz slope 1 12 cm kyr have deposited during holocene time when high sea level results in maximum water depth over the gibraltar sill and full development of the atlantic inflow and mediterranean outflow currents the transgressive sand sheet of the shelf and the mud layer underlying the surface contourite sand sheet of the slope correlate respectively with the late pleistocene sea level lowstand and apparent weak mediterranean outflow current

calculation of ice velocities in the jakobshavn isbrae area using airborne laser altimetry abstract the ability to measure velocities of fast moving glaciers is essential to the understanding and interpretation of their dynamics and related processes this is especially important in the jakobshavn drainage basin of the greenland ice sheet where a significant portion of the ice sheet mass loss occurs and the iceberg calving rate is high in this article we present a method for using airborne laser altimetry data to determine surface velocities in portions of the jakobshavn drainage basin that have distinct elevation features by examining correlations between repeat elevation surveys the motion of these features the most distinct of which are crevasses is tracked results show that for areas with a standard deviation in elevation in excess of 1 m displacement of features can be tracked to a precision of 1 2 m and the corresponding velocities can be retrieved the maximum velocity of the jakobshavn isbrae at its calving front is found to be nearly 7 km yr 1 ice stream boundaries and flow patterns can also be observed in the derived velocity data

rigorous 3d change determination in antarctic peninsula glaciers from stereo worldview 2 and archival aerial imagery abstract this paper presents detailed elevation and volume analysis of 16 individual glaciers grouped at four locations spread across the antarctic peninsula ap the study makes use of newly available worldview 2 satellite stereo imagery to exploit the previously untapped value of archival stereo aerial photography high resolution photogrammetric digital elevation models dems are derived to determine three dimensional glacier change over an unprecedented time span of six decades with an unparalleled mean areal coverage of 82 per glacier the use of an in house robust surface matching algorithm ensured rigorous alignment of the dems to overcome inherent problems associated with processing archival photography most notably the identification and correction of scale error in some datasets the analysis provides insight into one of the most challenging and data scarce areas on the planet by expanding the spatial extent north of the ap to include previously un studied glaciers located in the south shetland islands 81 of glaciers studied showed considerable loss of volume over the period of record the mean annual mass loss for all glaciers yielded 0 24 0 08 m w e per year with a maximum mass loss of up to 62 m w e and frontal retreat exceeding 2 2 km for stadium glacier located furthest north on elephant island observed volumetric loss was broadly though not always correlated with frontal retreat the combined mass balance of all 16 glaciers yielded 1 862 0 006 gt which corresponds to 0 005 mm sea level equivalent sle over the 57 year observation period

changes in mid depth north atlantic and mediterranean circulation during the late pliocene isotopic and sedimentological evidence abstract presently the intermediate depths of the north atlantic ocean are occupied by a great lens of warm saline water whose source is the mediterranean sea this water flows both westward and northward finally entering the norwegian sea where it may contribute to the formation of north atlantic deep water the late neogene history of mediterranean outflow in the atlantic can be monitored at dsdp ipod site 548 on the continental slope southwest of ireland using benthic foraminifera oxygen isotope values isotopic data from 154 samples indicate that mediterranean water was absent from the mid depth north atlantic from 3 4 to 3 2 ma ago however at about 2 9 ma ago the isotopic values at site 548 diverge from those recorded from the deep north atlantic and they can be interpreted to indicate the appearance of a new water mass possibly mediterranean water in the north atlantic water column this appearance may be related to climatic changes that occurred around the mediterranean basin at about 2 9 ma ago the analysis of 189 samples for grain size distributions shows that a significant increase in the silt size fraction occurs at the same level that isotopic analysis indicates a change in bottom waters at site 548 the grainsize data support the hypothesis that mid depth water mass changes occurred at about 2 9 ma ago

growth and erosion of a cold water coral covered carbonate mound in the northeast atlantic during the late pleistocene and holocene the first detailed stratigraphic record from a deep water carbonate mound in the northeast atlantic based on absolute datings u th and ams 14c and stable oxygen isotope records reveals that its top sediment sequences are condensed by numerous hiatuses according to stable isotope data mainly sediments with an intermediate signal are preserved on the mound while almost all fully glacial and interglacial sediments have either not been deposited or have been eroded later the resulting hiatuses reduce the late pleistocene sediment accumulation at propeller mound to amounts smaller than the background sedimentation the hiatuses most likely result due to the sweeping of the mound in turn with the re establishment of vigour interglacial circulation patterns after sluggish current regimes during glacials thus within the discussion if internal fluid driven or external environmentally driven processes control the evolution of such carbonate mounds our findings for propeller mound clearly point to environmental forcing as the dominant mechanism shaping deep water carbonate mounds in the ne atlantic during the late pleistocene and holocene

plio pleistocene climate evolution trends and transitions in glacial cycle dynamics abstract we describe the evolution of climate system dynamics by examining the climate response to changes in obliquity and precession over the last 5 3 myr in particular we examine changes in the shape of glacial cycles and the power of obliquity and precession response in benthic 18 o when the exponential trend in 18 o variance is removed its spectral power exhibits strong proportional responses to amplitude modulations in orbital forcing over most of the plio pleistocene precession responses correlate with modulations in forcing for the last 5 myr but 41 kyr response is sensitive to obliquity modulation only before 1 4 myr where responses are sensitive to modulations in forcing we demonstrate that glacial cycles are orbitally forced rather than being self sustained or paced by orbital changes the shapes of glacial cycles have several nonlinear properties which may be indicative of glacial interglacial differences in climate sensitivity or response time the saw tooth asymmetry of glacial cycles first appears shortly after the onset of major northern hemisphere glaciation and the relative duration of interglacial stages decreases at 1 4 myr collectively trends in the shape of glacial cycles and the sensitivity of 18 o to obliquity and precession are suggestive of major transitions in climate dynamics at approximately 2 5 and 1 4 myr but show no significant change associated with the appearance of strong 100 kyr cycles during the mid pleistocene transition

a major and long term pliocene intensification of the mediterranean outflow 3 5 3 3 ma ago largely continuous millennial scale records of benthic delta o 18 mg ca based temperature and salinity variations in bottom waters were obtained from deep sea drilling project dsdp site 548 east atlantic continental margin near ireland 1250 m water depth for the period 3 7 3 0 ma ago high epsilon nd values of 10 7 to 9 show that this site monitored changes in mediterranean outflow water mow throughout the mid pliocene bottom water variability at ocean drilling progam odp site 978 alboran sea 1930 m water depth provides a complementary record of mow composition near its west mediterranean source both sites show a singular and persistent rise in bottom water salinities by 0 7 1 4 psu and in densities by similar to 1 kg m 3 from 3 5 to 3 3 ma ago which is matched by an similar to 3 degrees c increase in bottom water temperature at site 548 this event suggests the onset of strongly enhanced deep water convection in the mediterranean sea and a related increase in mow flow as a result of major aridification in the mediterranean source region in harmony with model suggestions the enhanced mow flow has possibly intensified upper north atlantic deep water formation

monitoring topographic changes through 4d structure from motion photogrammetry application to a debris flow channel the study of fast geomorphic changes in mountain channels and hillslopes driven by intense geomorphic processes requires frequent and detailed topographic surveys in the last two decades high resolution topography hrt has provided new opportunities in the earth sciences these have benefited from important developments in surveying techniques methods sensors and platforms between these the application of structure from motion sfm photogrammetry has become a widely used method to acquire hrt and high resolution orthomosaics at multiple temporal and spatial scales sfm photogrammetry has revolutionized the possibility to collect multi temporal hrt in rugged or inaccessible environments like that observed in debris flow catchments however appropriate workflows incorporating survey planning data acquisition post processing and error and uncertainty assessment are required especially when multi temporal surveys are compared to study topographic changes through time in this paper we present a workflow to acquire and process hrt the workflow was applied in a debris flow channel of the moscardo torrent eastern italian alps due to the topographic complexity of the study area the sfm surveys were carried out integrating photos obtained from an unmanned aerial vehicle and from the ground this integration guarantees high data density and avoids shadows eight photogrammetric surveys were collected between december 2015 and august 2017 in this time interval five debris flows occurred the surveying and data processing procedure described in the workflow permitted to summarize and integrate all the analysis steps and helped to identify and minimize potential sources of error in the multi temporal sfm data what we consider here 4d our case study demonstrates how the developed workflow presented here allows studying the geomorphic effects of debris flows and check dams functionality in mountain environments

circulation in the glacial north atlantic inferred from grain size measurements records of nutrient proxies in marine sediments indicate that the nutrient distribution and hence circulation of the glacial north atlantic ocean was markedly different from that of today1 2 but these tracers are influenced by several biogeochemical factors unrelated to ocean circulation3 6 and thus do not provide a direct measure of the vigour of circulation distributions of grain size in marine sediments can provide such information owing to the sorting effects of currents7 8 if the characteristics of the input sediment flux are known here we present a record inferred from grain size measurements of variations in the relative strength of deep and intermediate currents in the eastern north atlantic over the past 25 000 years we find that glacial intermediate water flowed rapidly at depths of between 1 100 and 2 000 m in contrast deep water circulation was sluggish during the last glaciation but increased in strength shortly after the glacial maximum this would have resulted in increased heat flux to high latitudes and may have triggered sudden deglaciation deep current strengths declined again at the start of termination stage ia and during the younger dryas perhaps as a result of iceberg discharges the so called heinrich events9 10 a remarkably similar record of grain size variations has been found in the western north atlantic11 indicating that these changes in circulation are ocean wide

cenozoic alongslope processes and sedimentation on the nw european atlantic margin based on studies of sediment accumulations deposited from and erode by alongslope flowing ocean currents on the european continental margin from porcupine ireland to lofoten norway the evolution of the cenozoic paleocirculation was reconstructed as part of the stratagem project there is evidence of ocean current controlled erosion and deposition in the rockall trough in the faeroe shetland channel and on the voring plateau since the late eocene although the circulation pattern remains ambiguous the late palaeogene flow in the rockall trough was almost probably driven by southerly derived tethyan outflow water the extent and strength of any northerly derived flow is uncertain from the early neogene early mid miocene there was a massive regional expansion of contourite drift development both in the north atlantic and in the norwegian greenland sea this was most probably related to the development of the faroe conduit the opening of the fram strait and the general subsidence of the greenland scotland ridge these may have combined to cause a considerable acceleration in the exchange and overflow of deep waters between the arctic and atlantic oceans an early late neogene late early pliocene regional erosional event has been ascribed to a vigorous pulse of bottom current activity most probably the result of a global reorganisation of ocean currents associated with the closure of the central american seaway during the late neogene contourites and sediment drifts developed in deep water basins between units of glacigenic sediments as well as infill of several paleo slide scars these sediments were derived from areas of bottom current erosion as well as from the development of plio pleistocene prograding sediment wedges incorporating the extensive sediment supply derived from shelf wide ice sheets presently a profound winnowing prevails along the shelf and upper slope due to the inflowing currents of atlantic water depocentres of sediments derived from the winnowing are located locally in lower slope embayments and in slide scars

modelling mass balance using photogrammetric and geophysical data a pilot study at griesgletscher swiss alps the kinematic boundary condition at the glacier surface can be used to give glacier mass balance at a point as a function of changes in the surface elevation and of the horizontal and vertical velocities vertical velocity can in turn be estimated from basal slope basal ice velocity and surface strain in a pilot study on the tongue of griesgletscher swiss alps the applicability of the relation for modelling area wide ice flow and mass balance distribution is tested the key input of the calculations i e the area wide surface velocity field is obtained using a newly developed photogrammetric technique ice thickness is derived from radar echo soundings error estimates and comparisons with stake measurements show an average accuracy of approximately 0 3 m a for the calculated vertical ice velocity at the surface and 0 7 m a for the calculated mass balance due to photogrammetric restrictions and model inherent sensitivities the applied model appeared to be most suitable for determining area wide mass balance and ice flow on flatlying ablation areas but is so far not very well suited for steep ablation areas and most parts of accumulation areas nevertheless the study on griesgletscher opens a new and promising perspective for the monitoring of spatial and temporal glacier mass balance variations

significance of bottom currents in deep sea morphodynamics an example from the alboran sea we present an interdisciplinary study of the geomorphology sedimentology and physical oceanography of the alboran sea south western mediterranean sea to evaluate the potential role of bottom currents in shaping the spanish and moroccan continental margins and adjacent basins bathymetric and seismic data have allowed the recognition of the contourite deposits including depositional plastered sheeted channel related mounded confined elongated and separated drifts erosive moats channels and furrows and mixed terraces and scarps features hydrographic data offer new insights into the distribution of the mediterranean water masses and reveal that bottom circulation of the western intermediate water wiw and the levantine intermediate water liw interact with the spanish slope and the western mediterranean deep water wmdw on the moroccan slope spanish base of slope and deep basins the integration of distinct datasets and approaches allows a proposal of a new sedimentary model for the alboran sea that details the significance of bottom current processes in shaping deep sea morphology this model considers the bottom circulation of water masses governs physiography that interface positions of water masses with contrasting densities sculpt terraces on a regional scale and that the morphologic obstacles play an essential role in the local control of processes and water mass distributions our findings demonstrate the pivotal role of bottom water circulation in seafloor shaping and sedimentary stacking patterns for continental margins establishing a new outlook for future studies of deep marine sedimentation

ground based and uav based photogrammetry a multi scale high resolution mapping tool for structural geology and paleoseismology this contribution reviews the use of modern 3d photo based surface reconstruction techniques for high fidelity surveys of trenches rock exposures and hand specimens to highlight their potential for paleoseismology and structural geology we outline the general approach to data acquisition and processing using ground based photographs acquired from standard dslr cameras and illustrate the use of similar processing approaches on imagery from unmanned aerial vehicles uavs it is shown that digital map and trench data can be acquired at ultra high resolution and in much shorter time intervals than would be normally achievable through conventional grid mapping the resulting point clouds and textured models are inherently multidimensional x y z point orientation colour texture archival and easily transformed into orthorectified photomosaics or digital elevation models dems we provide some examples for the use of such techniques in structural geology and paleoseismology while pointing the interested reader to free and commercial software packages for data processing visualization and 3d interpretation photogrammetric models serve to act as an ideal electronic repository for critical outcrops and observations similar to the electronic lab book approach employed in the biosciences this paper also highlights future possibilities for rapid semi automatic to automatic interpretation of the data and advances in technology

optimizing photogrammetric dems for glacier volume change assessment using laser scanning derived ground control points photogrammetric processing of archival stereo imagery offers the opportunity to reconstruct glacier volume changes for regions where no such data exist and to better constrain the contribution to sea level rise from small glaciers and ice caps the ability to derive digital elevation model dem measurements of glacier volume from photogrammetry relies on good quality well distributed ground reference data which may be difficult to acquire this study shows that ground control points gcps can be identified and extracted from point cloud airborne lidar data and used to control photogrammetric glacier models the technique is applied to midtre lovenbreen a small valley glacier in northwest svalbard we show that the amount of ground control measured and the elevation accuracy of gcp coordinates based on known and theoretical error considerations has a significant effect on photogrammetric model statistics dem accuracy and the subsequent geodetic measurement of glacier volume change models controlled with fewer than 20 lidar control points or gcps from sub optimal areas within the swath footprint overestimated volume change by 14 53 over a 2 year period dems derived from models utilizing 20 25 or more gcps however gave volume change estimates within 4 of those from repeat lidar data 0 51 m a 1 between 2003 and 2005 our results have important implications for the measurement of glacier volume change from archival stereo imagery sources

seismic image of the cantabrian mountains in the western extension of the pyrenees from integrated escin reflection and refraction data abstract integrated analysis of normal incidence and large aperture seismic reflection data collected in 1992 and 1993 within the spanish escin and complementary projects provide a first complete n s crustal transect across the northern iberian peninsula and continental margin images of the crustal structure of the cantabrian mountains and their transition to the duero basin and to the cantabrian margin are obtained from a a 65 km long vertical reflection profile escin 2 on land b a 200 km long reversed refraction profile and c wide angle recordings of the marine escin 4 profile consistent results between reflectivity pattern and velocity depth distribution reveal important lateral variations in the deep structure the reflective crust imaged in the escin 2 profile changes its attitude from sub horizontal beneath the duero basin to north dipping beyond the mountain front basement thrusts are observed in the upper crust merging into a detachment at 6 s twt and may have triggered the alpine uplift of the range the moho is identified at the bottom of the reflective lower crust and deepens from 12 to 15 s at the northern end of the profile about 35 km inland modelling of the refraction data laterally extends the seismic image and provides evidence for variscan crustal features beneath the duero basin northwards the velocity in the lower crust decreases and the moho constrained by the wide angle data from profile escin 2 deepens to about 60 km ending abruptly at the shoreline the velocity depth model is constrained along the asturian platform up to the continental slope where the crust mantle boundary is located at 24 km depth this margin moho shows a progressive deepening southwards and extends to the coast where it is found at 30 km depth the present seismic data support an important alpine reworking and thickening of the crust under the cantabrian mountains the onshore offshore transition is marked by an imbrication of two crusts of very different thicknesses this signature offers a strong parallelism with the one previously observed further east across the pyrenees in the ecors seismic profile

sedimentary growth pattern on the northern argentine slope the impact of north atlantic deep water on southern hemisphere slope architecture large sedimentary deposits consisting of several major contourite drifts were studied by means of high resolution multichannel seismic data at the middle slope along the northern argentina continental margin to determine their evolutionary stages as well as to identify and assess the possible impact of northern source deep water nsdw on the slope architecture the imaged contouritic sediments allow decoding on the regional paleo oceanographic setting of the last 32 ma earliest contouritic sedimentation can be observed close to the eocene oligocene boundary based on an aggradational stacking pattern with a complex and wavy seismic facies pointing toward a hydrodynamically turbulent flow pattern this facies is most likely related to the opening of the drake passage associated with global cooling and a strengthening of surface intermediate and deep ocean currents in the southern ocean during the middle miocene plastered drift sequences with an aggradational reflection pattern were deposited their depositional style indicates weak non turbulent current conditions which are interpreted to be related to a vertical shift of water mass interfaces caused by the first formation of nsdw during the mid miocene climatic optimum on top the formation of plastered drift sequences led to the modern extent of the ewing terrace which was probably controlled by the continuous strengthening and thickening of nsdw until the final closure of the central american seaway cas during the pliocene and quaternary after the complete closure of the cas and under the influence of the full force of the nsdw mounded plastered drift sequences are built upon the ewing terrace generating the modern slope morphology therefore we suggest that deep water production in the northern hemisphere plays a significant role by controlling the shape of the continental slopes in the southwestern south atlantic since the middle miocene highlights slope of northern argentine continental margin is current controlled since 32 ma variability of northern source deep water nsdw controls sedimentary processes sedimentary processes are susceptible to changes of the brazil malvinas confluence impact of nsdw on slope processes is underestimated in the southern hemisphere

high resolution seismic stratigraphy of the galicia bank region and neighbouring abyssal plains nw iberian continental margin abstract the high resolution seismic stratigraphy of the galicia bank region and adjacent deposits of the neighbouring iberian and biscay abyssal plains was included as part of the geological studies conducted in the area where the oil tanker prestige wreck is located this seismic stratigraphy is characterized by five seismic units 5 to 1 from oldest to youngest lying above an irregular acoustic basement defined by a highly fractured system of horsts and grabens these faulted systems have controlled the local depositional architecture deforming fracturing relocating and distributing sediments since the valanginian three depositional models of facies can be recognized on the galicia bank region and surrounding abyssal plains bank escarpment and abyssal plain facies the bank facies reflects the depositional evolution from initial filling to obliterating stages of the horsts and grabens the escarpment facies has a local distribution and represents deposition associated with active slopes of the faulted escarpments the abyssal plain facies represents gravity flow deposits coming mostly from the bounded fault flanks of the galicia bank region the valanginian to quaternary sedimentary evolution of the galicia bank region reflects depositional responses to tectonic condition the occurrence of mass movements confirms that the syn rift period valanginian to aptian age along the galicia margin was diachronous beginning in the interior basin and shifting later toward the west of the galicia bank region deep galicia margin the albian to quaternary post rift evolution is characterized by a decrease in tectonic activity and sedimentary variations in the style of deposition valley and related features mass movement deposits contourites and drape deposits conditioned by changes in the sedimentary processes paleoenvironments and tectonic reactivation of the regional slopes the effects of tectonic movements persist as evidenced in areas where faulted escarpments and highs outcrop and in areas of near surface faulting the syn rift and post rift stages have also conditioned the depositional architecture of the prestige sinking area the evolution of the surrounding abyssal plains does not reflect the same pattern to tectonic condition

modeling river bed morphology roughness and surface sedimentology using high resolution terrestrial laser scanning 1 recent advances in technology have revolutionized the acquisition of topographic data offering new perspectives on the structure and morphology of the earth s surface these developments have had a profound impact on the practice of river science creating a step change in the dimensionality resolution and precision of fluvial terrain models the emergence of hyperscale survey methods including structure from motion photogrammetry and terrestrial laser scanning tls now presents the opportunity to acquire 3 d point cloud data that capture grain scale detail over reach scale extents translating these data into geomorphologically relevant products is however not straightforward unlike traditional survey methods tls acquires observations rapidly and automatically but unselectively this results in considerable noise associated with backscatter from vegetation and other artifacts moreover the large data volumes are difficult to visualize require very high capacity storage and are not incorporated readily into gis and simulation models in this paper we analyze the geomorphological integrity of multiscale terrain models rendered from a tls survey of the braided river feshie scotland these raster terrain models are generated using a new computationally efficient geospatial toolkit the topographic point cloud analysis toolkit topcat this performs an intelligent decimation of point cloud data into a set of 2 5 d terrain models that retain information on the high frequency subgrid topography as the moments of the locally detrended elevation distribution the results quantify the degree of terrain generalization inherent in conventional fluvial dems and illustrate how subgrid topographic statistics can be used to map the spatial pattern of particle size grain roughness and sedimentary facies at the reach scale

rapid thinning of parts of the southern greenland ice sheet aircraft laser altimeter surveys over southern greenland in 1993 and 1998 show three areas of thickening by more than 10 centimeters per year in the southern part of the region and large areas of thinning particularly in the east above 2000 meters elevation the ice sheet is in balance but thinning predominates at lower elevations with rates exceeding 1 meter per year on east coast outlet glaciers these high thinning rates occur at different latitudes and at elevations up to 1500 meters which suggests that they are caused by increased rates of creep thinning rather than by excessive melting taken as a whole the surveyed region is in negative balance

western extension of the iberian european plate boundary during the early cenozoic pyrenean convergence a new model abstract a dense seismic net work allows of drawing the western prolongation of the northern boundary of the iberian plate this early cenozoic deformed boundary is disrupted by two prominent nw se transform faults a kinematic reconstruction with a nw late cretaceous lower eocene motion of the iberian plate is proposed the azores biscay rise is interpreted as a short lived subduction zone whereas king s trough could be a transform fault

initiation of an active margin at the north iberian continent ocean transition 1 the north iberian or cantabrian margin located at the southern flank of the bay of biscay underwent successive tectonic regimes of rifting passive margin and compression from mesozoic to tertiary times a complete crustal cross section of the north iberian margin from the abyssal plain to the shoreline and a reconstruction of its undeformed upper cretaceous structure are presented here it is constrained after the compilation and interpretation of different geophysical data sets recently available in the area the reflective pattern is provided by deep seismic reflection profile escin 4 complemented by commercial profiles and well information from the north iberian platform and the velocity depth control comes from an onshore offshore wide angle seismic profile tested also with gravity modeling the detailed cross section of the meso tertiary basins that fill the platform and abyssal plain shows structures from the three main tectonic events 1 normal faults and asymmetric basins from the permian to lower cretaceous extensional stage 2 upper cretaceous sediments deposited under stable conditions during the passive margin period and 3 inverted faults thrusts and folds related to the tertiary compression the deep structure of the crust beneath the margin is poorly constrained from escin 4 profile that shows reflectivity in the lower crust only at a small area under the platform however the corresponding wide angle experiment provides a conspicuous image of the moho that shows a continued deepening toward the continent on the basis of the geophysical results we propose a new model for this margin where the lower crust is detached and underthrusted to the south as a result of the partial closure of the bay of biscay an interpreted mesozoic crustal scale extensional detachment could be the weakness zone that allowed the lower crust to slide southward under the upper crust resulting in the indentation of the cantabrian margin lower crust into the iberian crust plate convergence stopped at an early stage making this a unique area to study the initial stages of deformation of a passive margin

using an ultra long range terrestrial laser scanner to monitor the net mass balance of urumqi glacier no 1 eastern tien shan china at the monthly scale we describe the use of a terrestrial laser scanner tls to monitor the net mass balance of urumqi glacier no 1 eastern tien shan we used an ultra long range riegl vz 6000 tls which is specially designed for surveying snow and ice covered terrain to create repeated high spatiotemporal resolution dems focusing on the monthly scale 25 april 28 may 2015 net mass balance according to the tls derived dems the area of urumqi glacier no 1 was 1 558 km 2 on 25 april 2015 and the average surface elevation change was 0 225 m by comparing the results from the use of tls with the conventional glaciological mass balance method the correlation coefficient r 2 between glaciological elevation changes of individual stakes and the tls derived geodetic elevation change of corresponding points was 0 85 considering the uncertainty of both methods this is a promising result using the in situ measured snow densities snow pits of the glacier surface the geodetic net mass balance was 0 074 m w e which is slightly positive the mean uncertainty in the tls derived monthly net mass balance was 0 018 m w e showing that the tls surveying system presented accurate and relevant results and is therefore suitable to monitor mass balance evolution of mountain glaciers

high resolution stratigraphy of the mediterranean outflow contourite system in the gulf of cadiz during the late pleistocene the impact of heinrich events abstract a detailed high resolution stratigraphic analysis of the mediterranean outflow contourite system at the continental slope of the gulf of cadiz has been carried out through the correlation between a dense network of seismic reflection profiles sparker airgun 3 75 khz and parametric echosounder topas calypso giant piston and standard gravity cores from such correlation we determine a stacking pattern constituted by four main seismic units a d that are internally structured into ten subunits each subunit shows a single sequence formed by transparent seismic facies at the base to smooth parallel reflectors of moderate to high amplitude facies at the top being well correlated in the cores with a coarsening upward sequence the latest pleistocene holocene deposits form glacial interglacial depositional sequences related to cycles with a frequency range below the milankovitch band that corresponds to millennial timescale climatic changes such as dansgaard oeschger 1 5 ka and bond cycles 10 15 ka oxygen isotope records of planktonic foraminifera and the occurrence of ice rafted debris ird in the most recent contourite subunits show clear evidence of the influence of the north atlantic climatic conditions especially the climatic heinrich events h in the slope sedimentation of the gulf of cadiz and then in the circulation of the mediterranean outflow water mow the coarser contourite deposits are mostly associated with the last glacial maximum younger dryas and heinrich events on the central area of the middle slope during globally cooler conditions the mow was denser so that it was more active in deeper areas than today on the other hand during warm periods the mow became less dense favoring an increased intensity of the mow on the distal area of the upper slope therefore spatial and vertical fluctuations of the mow contourite system are strongly affected by global climate and oceanographic changes being clearly influenced by iceberg discharges and probably also by the resumption of thermohaline circulation in the north atlantic ocean during ice melting periods

submarine erosional troughs in the northern south china sea evidence for early miocene deepwater circulation and paleoceanographic change abstract the paleoceanography of the south china sea scs is poorly understood although recent cruises and an odp expedition leg 184 have provided a useful general framework here we report previously unrecognized multi km scale sedimentary structures consisting of coupled ridges and troughs within the early miocene strata using high resolution 3d seismic data from the northern scs margin the troughs are interpreted as linear and or arcuate erosional features which truncate the underlying strata they range in orientation from e w in the southern part of the study area to nearly ne sw in the northwestern part of the study area the spacing of erosional troughs varies from less than 0 1 km in the southern part to more than 3 km in the northern part and they are about 50 1500 m in width with a relief of 10 90 m the erosional troughs are parallel to the regional strike of the early miocene slope of the northern scs from their internal geometry context regional distribution and most importantly their orientation relative to the paleo slope gradient at the time of their formation it is argued that they formed due to the action of bottom currents linked to the broader paleo circulation regime in the basin we infer that the paleo bottom currents intruding from the pacific flowed along the northern scs slope resulting in the occurrence of localized erosional troughs as deep water masses impinged on and interacted with the sea floor topography this study provides new insights into the early miocene paleoceanography of the scs and demonstrates the utility of 3d seismic data to enhance our understanding of paleo bottom current circulation regimes

review of earth science research using terrestrial laser scanning abstract the application of advanced remote sensing technologies including terrestrial laser scanning tls to the earth sciences has increased rapidly in the last two decades improving the spatial and temporal resolution of data terrestrial laser scanning units have evolved into a common tool in studies of spectral and structural geology seismology natural hazards geomorphology and glaciology special consideration of the advantages and limitations of tls in each of these fields is discussed in depth in the context of important work published in each field the workflow used in a tls survey is crucial to the success of the survey and field specific earth science workflows are therefore also discussed products based on tls data such as triangulated irregular networks tin and digital surface models dsm are commonplace tools throughout the earth sciences and the use of these tools to measure slip distributions fault geometries aeolian transport river bed morphologies and flows and other research problems is expanded on where appropriate the review concludes with a discussion of recent trends in tls instrument development and their potential impact on the use of tls in the earth sciences in the future

the enya mounds a lost mound drift competition the genesis and evolution of cold water coral banks along the northeastern atlantic margin is known to be influenced by several factors among which the palaeotopography and nature of the coral settling surface the presence of bottom currents and sediment supply in this paper a case study is presented of the enya mound cluster located in the southernmost tip of the belgica mound province west of ireland below this mound cluster seismic stratigraphy revealed a yet unmapped local unconformity rd1b being part of a composite erosion event rd1 as such from the late miocene to late pliocene at least two erosional events have incised the margin ending with the final rd1a moundbase unconformity acting as a base for the enya mounds during the quaternary the mounds became outgrown and were covered by a mounded contourite drift in addition they are closely associated with a cluster of seabed pockmarks the bottom current regime which became active since the middle pleistocene has certainly influenced the fate of this mound cluster the occurrence of the pockmarks seems to be related to relatively recent fluid migration processes however leaving an open question if any previous seepage phases were involved in the growth or initiation of the coral banks

contourite depositional system on the argentine slope an exceptional record of the influence of antarctic water masses a significant contourite depositional system cds on the continental slope of the southern argentine margin is described here for the first time this system contains both erosive and depositional features that have resulted from several factors including topographic intensification of the antarctic sourced water masses the systematic northward decrease in speed of these water masses a northward increase of downslope sedimentary processes and local tectonic influences this system is an exceptional example of a cds that started to develop at the time of the eocene oligocene boundary potentially coeval with the opening of the drake passage however a new margin morphology characterized by a complex terraced slope lacking any continental rise developed after a major paleoceanographic change in the middle to late miocene we infer that this change resulted from the extension of north atlantic deep water circulation into the southern hemisphere and the deepening of antarctic bottom water circulation in the argentine basin

contourites of the gulf of cadiz a high resolution record of the paleocirculation of the mediterranean outflow water during the last 50 000 years the mediterranean outflow water mow paleocirculation during the last 50 000 years has been inferred from the grain size distribution of contourite beds in core md99 2341 from the gulf of cadiz southern iberian margin atlantic ocean three main contourite facies are described their vertical succession defines two contourite sequences that reveal past variations of the mow bottom current velocity a comparison of contourite sequences and the planktonic 18o record of core md99 2341 with the 18o record from greenland ice core gisp2 show a close correlation of sea surface water conditions and deep sea contouritic sedimentation in the gulf of cadiz with northern hemisphere climate variability on millennial timescales a high mow velocity prevailed during dansgaard oeschger stadials heinrich events and the younger dryas cold climatic interval the mow velocity was comparatively low during the warm dansgaard oeschger interstadials bolling allerod and the early holocene rapid sea level fluctuations on the order of 35 m during marine oxygen isotope stage 3 are considered to have exerted limiting controls on the mow volume transport and thus positively modulated the mow behaviour during the last 50 kyr

signatures of the mediterranean outflow from a north atlantic climatology 1 salinity and density fields using historical data from the national oceanic data center the climatology of the eastern north atlantic basin has been investigated for the purpose of detailing the mediterranean outflow water in terms of its salinity density and flow patterns part 1 of this work is a descriptive analysis of the fate of the mediterranean water once it flows out of the strait of gibraltar tracing the salinity and density signatures high resolution maps of the climatological outflow are presented with an emphasis on the continuity of the water from its source from the climatological fields a continuous signal of mediterranean water is tracked northward to 50 20 n yet its westward advection is limited to the tagus basin recirculations of mediterranean water in the gulf of cadiz and in the bay of biscay deduced from property signals are also detailed iorga and lozier this issue present absolute velocity fields from a diagnostic model constrained by geostrophic dynamics conservation of mass and no flux boundary conditions

a distributed surface energy balance model for a small valley glacier i development and testing for haut glacier d arolla valais switzerland this paper describes the development and testing of a distributed surface energy balance model used to calculate rates of surface melting at haut glacier d arolla valais switzerland the model uses a digital elevation model dem of the glacier surface and surrounding topography together with meteorological data collected at a site in front of the glacier to determine hourly or daily totals of the energy balance components and hence of melting over the entire surface of the glacier with a spatial resolutio of 20 m the model can also be used to determine temporal and spatial variations in snow depth snow line position and glacier surface albedo calculations from the model are compared with observations made along the glacier centre line in 1990 and in general the model performs very well the correlation coefficients between calculated and measured snow line elevation albedo and ablation are 0 99 0 85 and 0 81 respectively the main source of error between modelled and measured values of these variables is probably inadequacies in the parameterization of albedo used in the model

seismic patterns of a muddy contourite fan vema channel south brazilian basin and a sandy distal turbidite deep sea fan cap ferret system bay of biscay a comparison abstract the aim of this paper is to discriminate the depositional facies geometries and mechanisms of deposition of contouritic fans from those of turbidite distal fans with a view to provide better resolution of reservoir prediction two examples are analysed the vema contouritic drift in the south brazilian basin and the cap ferret turbiditic fan in the bay of biscaye the vema contourite fan is a neogene mud rich accumulation 200 400 m thick fed by antarctic bottom water bottom currents and located downstream of the rio grande rise it forms one single mound fan shaped body in between two major channels and where the main part of the deep circulation is funnelled into as a result of the morphological and hydrological background the comourite drift progrades mostly downstream the accumulation was built as several depositional units channel levee systems bounded by widespread discontinuities showing erosional patterns this resulted from episodes of strong and or unstable current activity producing the discontinuities alternating with periods of relatively weak and stable currents and major deposition the pliocene quaternary cap ferret distal deep sea fan is a thick 500 m sand rich turbiditic accumulation fed directly by an uplifting mountain range the accumulation is developed downstream of a main turbiditic feeder channel and the volume of sediment involved is much higher than for the vema contourite fan it shows a complex network of shallow channels and low relief levees which merge downstream into thin sandy sheet like deposits several depositional units are stacked vertically each unit is built by the lateral migration of a channel levee system the stacking pattern of the successive units is prograding towards the basin the presence of major discontinuities cutting throughout a whole accumulation and the fairly irregular geometry of the channel levee deposits absence of any obvious migrating trend appear to be the most distinctive features of a contourite fan on the other hand the lateral migration of the channel level geometries and the presence of erosional surfaces of limited extent and restricted to the channels are the main diagnostic features of a distal turbidite fan otherwise the seismo facies are fairly similar in both sedimentary bodies

multi process generated sediment waves on the landes plateau bay of biscay north atlantic detailed analyses of recently collected bathymetric and sparker seismic data support a new interpretation of the landes plateau field of sediment waves located on the aquitaine upper continental slope bay of biscay the wave geometry previously described as the result of a major sediment failure is interpreted as a structure with a complex origin including the interaction of depositional and gravity deformation processes depositional processes are mainly recorded by the upslope migrating pattern of the waves resulting from oblique or sigmoid downlap reflections on the upslope flank of the waves and by toplapping and truncated reflections on the downslope flank hemipelagic and turbiditic sedimentation may be involved in the wave building as well as contouritic processes that could be related to the existing northward polar current and internal waves gravity deformations are syndepositional discontinuous and of low amplitude affecting thick layers which alternate with undeformed layers they seem to correspond to gentle sediment creeping or stretching associated with minor listric or compaction like faults and possible limited back rotation of sediment blocks these multi process generated sediment waves could be rather common on the continental margins as they could have been mistaken with either depositional or deformational structures

rapid low cost photogrammetry to monitor volcanic eruptions an example from mount st helens washington usa we describe a low cost application of digital photogrammetry using commercially available photogrammetric software and oblique photographs taken with an off the shelf digital camera to create sequential digital elevation models dems of a lava dome that grew during the 2004 2008 eruption of mount st helens msh volcano renewed activity at msh provided an opportunity to devise and test this method because it could be validated against other observations of this well monitored volcano the datasets consist of oblique aerial photographs snapshots taken from a helicopter using a digital single lens reflex camera twelve sets of overlapping digital images of the dome taken during 2004 2007 were used to produce dems and to calculate lava dome volumes and extrusion rates analyses of the digital images were carried out using photogrammetric software to produce three dimensional coordinates of points identified in multiple photos the evolving morphology of the dome was modeled by comparing successive dems results were validated by comparison to volume measurements derived from traditional vertical photogrammetric surveys by the us geological survey cascades volcano observatory our technique was significantly less expensive and required less time than traditional vertical photogrammetric techniques yet it consistently yielded volume estimates within 5 of the traditional method this technique provides an inexpensive rapid assessment tool for tracking lava dome growth or other topographic changes at restless volcanoes

morphosedimentary features and recent depositional architectural model of the cantabrian continental margin abstract multibeam bathymetry high sleeve airguns and very high resolution parametric system topas seismic records were used to define the morphosedimentary features and investigate the depositional architecture of the cantabrian continental margin the outer shelf down to 180 245 m water depth displays an intensively eroded seafloor surface that truncates consolidated ancient folded and fractured deposits recent deposits are only locally present as lowstand shelf margin deposits and a transparent drape with bedforms the continental slope is affected by sedimentary processes that have combined to create the morphosedimentary features seen today the upper down to 2000 m water depth and lower down to 3700 4600 m water depth slopes are mostly subject to different types of slope failures such as slides mass transport deposits a mix of slumping and mass flows and turbidity currents the upper slope is also subject to the action of bottom currents the mediterranean water mw that interact with the le danois bank favouring the reworking of the sediment and the sculpting of a contourite system the continental rise is a bypass region of debris flows and turbidity currents where a complex channel lobe transition zone cltz of the cap ferret fan develops the recent architecture depositional model is complex and results from the remaining structural template and the great variability of interconnected sedimentary systems and processes this margin can be considered as starved due to the great sediment evacuation over a relatively steep entire depositional profile sediment is eroded mostly from the cantabrian and also the pyrenees mountains source and transported by small stream river mountains to the sea it bypasses the continental shelf and when sediment arrives at the slope it is transported through a major submarine drainage system large submarine valleys and mass movement processes down to the continental rise and adjacent biscay abyssal plain sink factors controlling this architecture are tectonism and sediment source dispersal which are closely interrelated whereas sea level changes and oceanography have played a minor role on a long term scale

benthic dynamics at the carbonate mound regions of the porcupine sea bight continental margin a brief review is given of some dynamical processes that influence the benthic dynamics within the carbonate mound provinces located at the porcupine bank sea bight margin ne atlantic the depth range of the mounds in this region 600 1 000 m marks the upper boundary of the mediterranean outflow water above which eastern north atlantic water dominates both water masses are carried northwards by the eastern boundary slope current in the benthic boundary layer both the action of internal waves and other tidal period baroclinic waves may enhance the bottom currents and add to both the residual and maximum flow strength both residual and maximum bottom currents vary at different mound locations with stronger currents found at belgica se porcupine sea bight mound and pelagia nw porcupine bank mound regions whilst weakest currents are found at the hovland and magellan mounds at the northern sea bight margin the differences may be attributed to the presence of internal waves pelagia or bottom intensified diurnal waves belgica these different dynamical regimes are likely to have implications for the distribution patterns of live coral at the different locations

vivaldi 1991 a study of the formation circulation and ventilation of eastern north atlantic central water abstract a synoptic hydrographic data set comprising 32 full depth ctd casts and 2500 ctd seasoar profiles to 500 m is used to describe the s properties and circulation of central water east of the mid atlantic ridge and between 39 n and 54 n eastward transport of 20 10 6 m 3 s 1 in the north atlantic current turns entirely northwards to the west of 54 n 20 w this transport consists in the upper layers of western north atlantic water freshened at temperatures below 10 c by mixing with subarctic intermediate water northern and southern branches of the north atlantic current are well defined and both turn northwards west of 20 w a further 10 10 6 m 3 s 1 of eastern north atlantic water forms and recirculates anticyclonically to the west of spain south of the north atlantic current and north of 40 n eastern north atlantic water is most weakly stratified east of 20 w and there is clear correlation between weakly stratified pycnostads and positive salinity anomalies relative to western north atlantic water thus eastern north atlantic water is a winter mode water in which strong winter cooling has increased the density and hence also the salinity anomaly at a given temperature near the southern entrance to the rockall trough there is evidence that salinities are also increased by mediterranean water influence circulation south of the north atlantic current is complex there is no evidence for direct ventilation southwards across 40 n where water properties s potential vorticity and cfc 113 and historical data all indicate westward ventilation east of 24 w with weak southward ventilation occurring further west in the vicinity of the azores the circulation pattern suggested is remarkably similar to that proposed by helland hansen and nansen in 1926 the eastern north atlantic geophysiske publicajoner 4 1 76 with anticyclonic circulation of colder eastern north atlantic water north of 40 n meeting warmer water from south of 40 n circulating cyclonically north of the azores current the distribution of pycnostads and s properties between 20 w and 35 w north of the azores indicates alternate bands of western and eastern north atlantic water moving eastward and westward respectively including evidence for westward motion immediately south of the southern branch of the north atlantic current possibly by westward propagation of anticyclonic eddies containing deep pycnostads

integrating structure from motion photogrammetry into rock weathering field methodologies despite recent rapid advances in the field of structure from motion sfm photogrammetry the use of high resolution data to investigate small scale processes is a relatively underdeveloped field in particular rock weathering is rarely investigated using this suite of techniques this research uses a combination of traditional non destructive rock weathering measurement techniques rock surface hardness and sfm to map deterioration and loss of cohesion of the surface using 3 dimensional data the results are used to interpret weathering behaviour across two different lithologies present on the site namely shale and limestone this new approach is tested on seven sites in longyearbyen svalbard where active weathering of a rock surface was measured after 13 years of exposure to extreme temperature regimes and snow cover the surface loss was quantified with sfm and combined with rock surface hardness measurement distributions extrapolated in gis the combined results are used here to quantify the difference in response of both lithologies to these extreme temperatures this research demonstrates the potential for further integration of sfm in rock weathering research and other small scale geomorphological investigations in particular in difficult field conditions where portability of field equipment is paramount

combining satellite multispectral image data and a digital elevation model for mapping debris covered glaciers automated glacier mapping from satellite multispectral image data is hampered by debris cover on glacier surfaces supraglacial debris exhibits the same spectral properties as lateral and terminal moraines fluvioglacial deposits and bedrock outside the glacier margin and is thus not detectable by means of multispectral classification alone based on the observation of low slope angles for debris covered glacier tongues we developed a multisource method for mapping supraglacial debris the method combines the advantages of automated multispectral classification for clean glacier ice and vegetation with slope information derived from a digital elevation model dem neighbourhood analysis and change detection is applied for further improvement of the resulting glacier debris map a significant percentage of the processing can be done automatically in order to test the sensitivity of our method against different dem qualities it was also applied to a dem obtained from aster stereo data additionally we compared our multisource approach to an artificial neural network ann classification of debris using only multispectral data while the combination with an aster derived dem revealed promising results the ann classification without dem data does not

investigations of the bottom current sculpted margin of hatton bank ne atlantic the northwest hatton bank margin is an ideal locality to demonstrate the interaction between bottom currents and slope configuration in controlling the distribution and morphology of bottom current deposits the slope area investigated is isolated from any major terrigenous sediment supply and at present is influenced by the deep northern boundary current dnbc swath bathymetry and high resolution acoustic data allow us to evaluate both local and regional controls on slope sedimentation and the possible mechanisms for bottom current velocity variability across a slope setting within the nw european continental margin the slope exhibits sculpting by bottom currents that flow in a predominantly southwest to northeast direction and is only locally modified by slope failures positive relief features such as the endymion spur play an important role in constraining and accelerating bottom current flow and consequently in redistributing sediment along the margin we demonstrate that the size morphology and distribution of bottom current deposits along the slope vary as a function of the interaction between bottom currents regional slope orientation and local seafloor topography

geomorphic effectiveness of check dams in a debris flow catchment using multi temporal topographic surveys abstract torrent control works such as grade control dams and sediment retention dams are structural measures for controlling debris flows and debris floods in spite of the widespread presence of such hydraulic structures in steep mountain streams worldwide there are still few studies monitoring the effects of check dams on sediment dynamics the use of repeated topographic surveys allows us to characterize debris flow activity at multiple temporal and spatial scales and its interaction with torrent control works structure from motion sfm technique paired with multi view stereo mvs algorithms represents a low cost opportunity to conduct such multi temporal surveys this enables us to better study the effects of individual debris flows track geomorphic changes and evaluate the effectiveness of torrent control works e g check dams the effect of check dams on sediment dynamics is investigated by means of multi temporal topographic surveys before and after debris flow events in the moscardo torrent eastern italian alps where two check dams have recently been built multi temporal sfm based on images taken from the ground in combination with imagery taken by an unmanned aerial vehicle uav is used to obtain dems and to study topographic changes through the comparison of repeat dems dem of difference i e dod the results show that the new check dams considerably modified sediment dynamics in the studied channel but their performance cannot be considered satisfactory the sediment flowed around the upstream check dam on the right wing while deep erosion observed downstream of the check dam threatened to undermine the foundation s stability moreover debris flow lobes deposited upstream of the check dams could act as sources of sediment further increasing downstream debris flow volume the analysis proposed in this work could help improve design strategies and permitting the identification of a proper site for check dam building

environmental changes and growth history of a cold water carbonate mound propeller mound porcupine seabight on and off mound sediment cores from propeller mound hovland mound province porcupine seabight were analysed to understand better the evolution of a carbonate mound the evaluation of benthic foraminiferal assemblages from the off mound position helps to determine the changes of the environmental controls on propeller mound in glacial and interglacial times two different assemblages describe the holocene and marine isotope stage mis 2 and late mis 3 31 kyr bp the different assemblages are related to changes in oceanographic conditions surface productivity and the waxing and waning of the british irish ice sheet biis during the last glacial stages the interglacial assemblage is related to a higher supply of organic material and stronger current intensities in water depth of recent coral growth during the last glaciation the benthic faunas showed high abundances of cassidulinid species implying cold bottom waters and a reduced availability of organic matter high sedimentation rates and the domination of elphidium excavatum point to shelf erosion related to sea level lowering 50 m and the progradation of the biis onto the shelf a different assemblage described for the on mound core is dominated by discanomalina coronata gavelinopsis translucens planulina ariminensis cibicides lobatulus and to a lower degree by hyrrokkin sarcophaga these species are only found or show significantly higher relative abundances in on mound samples and their maximum contribution in the lower part of the record indicates a higher coral growth density on propeller mound in an earlier period they are less abundant during the holocene however this dataset portrays the boundary conditions of the habitable range for the cold water coral lophelia pertusa which dominates the deep water reefal ecosystem on the upper flanks of propeller mound the growth of this ecosystem occurs during interglacial and interstadial periods whereas a retreat of corals is documented in the absence of glacial sediments on mound glacial conditions with cold intermediate waters a weak current regime and high sedimentation rates provide an unfavourable environmental setting for lophelia corals to grow a late pleistocene decrease is observed in the mound growth for propeller mound which might face its complete burial in the future as it already happened to the buried mounds of the magellan mound province further north

palaeomagnetic determination of emplacement temperature of vesuvius ad 79 pyroclastic deposits the city of herculaneum was hurried under 20 m of pyroclastic deposits during the ad 79 eruption of vesuvius whose crater is only 7 km to the east these deposits have been interpreted as the deposits of mudflows1 or hot pyroclastic flows2 5 maury s studies6 of incinerated wood in herculaneum demonstrate heating to at least 400 c we have studied the variation of remanent magnetism with temperature for specimens taken from the deposits including specimens of the matrix material and of embedded lithic fragments we conclude that the temperature of the deposit at emplacement is unlikely to have been greater than 400 c which further supports the interpretation of the pyroclastic deposits at herculaneum as largely ignimbrites hot pyroclastic flow deposits

subduction related structures in the north iberian margin the oblique convergence of eurasia and iberia since the early cretaceous caused the formation of the pyrenean intracontinental collisional orogen in the east and progressed to continent ocean collision with subduction of the bay of biscay oceanic crust beneath the north iberian margin in the west two deep multichannel seismic profiles iam 12 and escin 4 integrated with gravity modeling and other geological and geophysical data provide the crustal scale architecture of this margin and its tectonic evolution during the convergence the north iberian margin is modeled with a south or south southeast dipping oceanic crust beneath the outer part of the continental shelf mesozoic basins on the shelf were inverted during the tertiary and compressional activity continued until recent times in the escin 4 section while a shallower probably neogene age basin is subjected to active recent erosion in the iam 12 section in the oceanic areas a marginal trough deepens and widens toward the east as a result of the regional east dip of the oceanic basement the accretionary prism increases in size from west to east 18 56 km and its internal structure and morphology varies along strike the prism is buried by postcorivergence sediments in both sections and in the iam 12 section appears to have been active at least during lutetian to burdigalian times the crustal scale structure of the north iberian margin is that of an arrested subduction zone in which a remnant oceanic basin was being consumed near two continental plates that collided obliquely

estimates of the mean circulation in the deep 2 000m layer of the eastern north atlantic a total of 131 current meter records of between 6 and 24 month duration are analysed to describe the deep flow field of the eastern north atlantic from 19 to 54 n and from the continental slope to the mid atlantic ridge mean flows are weak and may be statistically indeterminate in some records and locations but appear to indicate cyclonic circulations around the iberia and porcupine abyssal plains with a generally southward flow along the mid atlantic ridge and a deep northward slope current where measurements exist along the eastern boundary the deepest inflow to the north eastern basin that has been identified to date takes place through the discovery gap of 4 700 m sill depth at 37 25 n 15 45 w in the azores portugal ridge south of that ridge observations are sparse and no systematic circulation is yet evident these observations are discussed in relation to recent geostrophic estimates of the deep circulation

the le danois contourite depositional system interactions between the mediterranean outflow water and the upper cantabrian slope north iberian margin abstract the le danois contourite depositional system cds located in an intraslope basin along the cantabrian margin is unique with respect to the known sedimentary systems along the upper slope of the biscay margin whereas the steep biscay slopes are dominated by downslope processes the le danois cds has been generated by alongslope processes and has a strong potential to contain a record of the neogene palaeoceanography this paper will focus on the onset development and present day functioning of this system with respect to its unique morphological control and the responsible local oceanographic processes new bathymetric and seismic reflection data show that the past and present le danois cds is shaped by the mediterranean outflow water conditioned by seafloor irregularities and two topographic highs the large le danois bank and the smaller vizco high the seismic stratigraphic analysis carried out on the contourite deposits has allowed to identify 3 seismic sequences separated by 3 major regional discontinuities changes in depositional styles the vertical stacking of seismic units and the nature of the discontinuities suggest a correlation with the development of the cadiz cds and well known palaeoceanographic events along the ne atlantic margin the first clues for bottom current deposits are identified in the lower sequence which is developed after tentatively the lower pliocene the drift deposits of both the lower and middle sequences were confined into two palaeobasins within the intraslope basin however from the middle pleistocene revolution 0 9 ma onwards the contouritic deposition is intensified due to the switch to a full glacial mode with 100 ka cyclicity this has allowed the development of the present day depositional and erosive features such as respectively elongated mounded and separated drifts plastered drifts moats and slide scars

glacier mass balance determination by remote sensing and high resolution modelling an indirect methodology for determining the distribution of mass balance at high spatial resolution using remote sensing and ice flow modelling is presented the method based on the mass continuity equation requires two datasets collected over the desired monitoring interval i the spatial pattern of glacier surface elevation change and ii the mass flux divergence field at haut glacier d arolla valais switzerland the mass balance distribution between september 1992 and september 1993 is calculated at 20 m resolution from the difference between the pattern of surface elevation change derived from analytical photogrammetry and the mass flux divergence field determined from three dimensional numerical flow modelling constrained by surface velocity measurements the resultant pattern of mass balance is almost totally negative showing a strong dependence on elevation but with large localized departures the computed distribution of mass balance compares well r 2 0 91 with mass balance measurements made at stakes installed along the glacier centre line over the same period despite the highly optimized nature of the flow modelling effort employed in this study the good agreement indicates the potential this method has as a strategy for deriving high spatial and temporal resolution estimates of mass balance

recirculating components to the deep boundary current of the northern north atlantic abstract the meridional overturning system of the north atlantic is conventionally thought of as transporting warm water 4 c to high latitudes and covd water to low latitudes the northern cold water sources for this system are dense overflow from the nordic seas and less dense water from the labrador sea lsw the overflow components are carried westward by a deep northern boundary current dnbc that is shown here actually to begin southeast of the overflow regions the dnbc lies along the southern side of a system of islands and submarine ridges that divides the nordic seas from the subpolar basins the overflows act to increase the transport of the dnbc and this transport is further increased through the entrainment of warm waters once inside the labrador sea the dnbc is joined by lsw before continuing south to low latitudes as a cold deep western boundary current dwbc however published transport estimates are larger than can be explained by warm water entrainment alone thus indicating entrainment also of recirculating cold components the subject of this paper their sources are shown to be the lsw and cold abyssal waters originating from the southern hemisphere the lsw is entrained downward into the denser part of the dnbc and laterally into the upper part of the dwbc whereas the cold abyssal waters are supplied by an eastern intensified northward flow in the eastern atlantic that serves as the initial source of the dnbc and by a similar northward flow in the western atlantic the meridional overturning system described includes recirculations and poleward transport of cold water in addition tothe components described by the conventional system the cold abyssal waters in both the eastern and western basins have relatively low levels of oxygen and high concentrations of silicate reflecting their southern origin but their influence in the northwestern atlantic is somewhat obscurred by strong recirculating cyclonic gyres in the newfoundland and labrador basins this influence is detected by a deep silicate maximum extending poleward from the mid latitude western atlantic through the two gyres with eastern concentration and recirculating back diluted toward the south in the dwbc within the respective basins such a maximum also extends northward through the irminger basin into the dnbc but there is an ambiguity as to whether this is a direct extension of the signal from the south in the western basin or if it comes from the mid latitude eastern basin by way of westward flow through the charlie gibbs fracture zone it is perhaps consequence of both estimates of the volume transports of the various recirculating cold components indicate that they supply about as much water to the deep boundary currents as do the combined cold water sources in the north

the contourite depositional system of the gulf of cadiz a sedimentary model related to the bottom current activity of the mediterranean outflow water and its interaction with the continental margin the present paper is mostly a synthesis of work conducted on the continental margin of the gulf of cadiz using a broad database collected by several cruises and projects supported by the spanish research council and the nrl and naval oceanographic office usa including bathymetry sidescan sonar imagery seismic profiles sediment cores submarine photographs and physical oceanographic data these data have enabled us to establish a detailed understanding of the morphologic development of the margin its pliocene and quaternary stratigraphy and a full characterization of the contourite depositional system cds generated by the mediterranean outflow water mow the northern margin of the gulf of cadiz shows the following distinct features a an active compressive framework where the cadiz allocthonous unit provides an unstable substratum for late miocene pliocene and quaternary sedimentation b a relative lack of submarine canyons except in the western area of the algarve margin c a very broad continental slope that lacks a marked continental rise d a middle slope dominated by along slope processes driven by the mow which has generated a complex cds during the pliocene and quaternary and e an irregular lower slope and abyssal plain region dominated by down slope processes that is partly detached from an upper slope source region the cds is composed of both depositional and erosive features the main depositional features are characterised by sedimentary wave fields sedimentary lobes mixed drifts plastered drifts elongated mounded and separated drifts and sheeted drifts the main erosive features are contourite channels furrows marginal valleys and moats these various depositional and erosive features have a specific location along the margin and their detailed distribution is essential to understand the present and past interaction of the mow with the middle slope based on this distribution five morphosedimentary sectors have been identified within the cds which from east to west are 1 proximal scour and sand ribbons 2 overflow sedimentary lobe 3 channels and ridges 4 active contourite drifts and 5 submarine canyons the development of the cds has been controlled in general by the pliocene and quaternary environmental and paleoceanographic changes and by the morphology of the margin but in detail the development of each of these sectors is related to systematic deceleration of the mow as it flows westwards to the interaction with the margin bathymetry and to the effects of coriolis force our comprehensive sedimentary model for the cds defines the gulf of cadiz margin as a mixed contourite turbidite system with a detached combined drift fan morphology this is different from many other contourite influenced margins where the contourite processes are dominant on the middle slope and separated from the down slope processes which are characteristic on the lower slope and abyssal plains

evidence for enhanced mediterranean thermohaline circulation during rapid climatic coolings molecular biomarkers c37 alkenones n nonacosane and n hexacosanol and toc are used together with benthic 18o and 13c data to document the hydrographic response of the western mediterranean sea to rapid climatic variability these proxies are recorded in core md 95 2043 alboran sea affording the study of the dansgaard oeschger d o and heinrich he variability during the last glacial period the results suggest that rapid changes in the western mediterranean thermohaline circulation occurred in parallel to sea surface temperature oscillations enhanced deep water ventilation occurred during cold intervals he and d o stadials probably driven by a strengthening of north westerly wind over the north western mediterranean sea in contrast decreased intensity of the thermohaline circulation is detected during warm intervals d o interstadials which led to low oxygenated deep water masses and better preservation of the organic matter in the sediment

mediterranean outflow strengthening during northern hemisphere coolings a salt source for the glacial atlantic abstract high resolution grain size and magnetic susceptibility records from the eastern gulf of cadiz site md99 2339 1170 m water depth reveal contourites formed by the mediterranean outflow mow during the last 47 kyr bp oscillations in the mow s intensity occurred in phase with greenland temperature variations with a stronger outflow during northern hemisphere coolings such as dansgaard oeschger stadials heinrich events and the younger dryas benthic 13c data implies the western mediterranean deep water as one of the main sources feeding the outflow current while differential changes in the properties of the mediterranean source and entrained north atlantic central water largely control the mow s strength detailed studies for heinrich events 1 4 and 5 show that the flow strength peaked only when subtropical surface waters prevailed in the eastern gulf of cadiz while incursions of icebergs and subpolar surface water were not favorable for the mow s intensification as the mow was strong when the atlantic s thermohaline circulation thc was weakened the heat and salt injected by the mow into the intermediate north atlantic waters might have preconditioned the thc to switch from the stadial to the interstadial mode

structure from motion photogrammetry a low cost effective tool for geoscience applications abstract high resolution topographic surveying is traditionally associated with high capital and logistical costs so that data acquisition is often passed on to specialist third party organisations the high costs of data collection are for many applications in the earth sciences exacerbated by the remoteness and inaccessibility of many field sites rendering cheaper more portable surveying platforms i e terrestrial laser scanning or gps impractical this paper outlines a revolutionary low cost user friendly photogrammetric technique for obtaining high resolution datasets at a range of scales termed structure from motion sfm traditional softcopy photogrammetric methods require the 3 d location and pose of the camera s or the 3 d location of ground control points to be known to facilitate scene triangulation and reconstruction in contrast the sfm method solves the camera pose and scene geometry simultaneously and automatically using a highly redundant bundle adjustment based on matching features in multiple overlapping offset images a comprehensive introduction to the technique is presented followed by an outline of the methods used to create high resolution digital elevation models dems from extensive photosets obtained using a consumer grade digital camera as an initial appraisal of the technique an sfm derived dem is compared directly with a similar model obtained using terrestrial laser scanning this intercomparison reveals that decimetre scale vertical accuracy can be achieved using sfm even for sites with complex topography and a range of land covers example applications of sfm are presented for three contrasting landforms across a range of scales including an exposed rocky coastal cliff a breached moraine dam complex and a glacially sculpted bedrock ridge the sfm technique represents a major advancement in the field of photogrammetry for geoscience applications our results and experiences indicate sfm is an inexpensive effective and flexible approach to capturing complex topography

late glacial to holocene history of the mediterranean outflow evidence from benthic foraminiferal assemblages and stable isotopes at the portuguese margin records of benthic foraminiferal assemblage variations and benthic 13c along 12 sediment cores from the western iberian margin between 36 and 42 n at water depths from 820 to 3580 m are used to monitor fluctuations of the mediterranean outflow water mow during the past 30 ka the chronostratigraphy of the cores is based on planktonic 18o records 14c ams dating and the recognition of heinrich events h1 through h4 increased abundances of suspension feeding benthic foraminifers denoted as epibenthos group closely match areas where the recent mow core layers impinge on the continental slope at 800 and 1300 m water depth and near bottom current velocities are enhanced elevated epibenthos group abundances increased benthic 13c and sedimentological evidence for winnowing and erosion are found in glacial sections up to the earliest termination i in cores at water depths between 1600 and 2200 m off southern portugal the combined evidence reveals enhanced current activity at these depths due to a deep glacial mow the mow advection at the portuguese margin during the last glacial was about 700 m deeper than today conceivably forced by increased mow density due to higher salinity and colder temperatures of mediterranean waters the deep mow current gradually decreased in strength and shoaled to 1300 m water depth during the termination and early holocene a shallow mow core layer became active with the onset of termination i at depths between 600 and 1000 m both the shallow and deep mow current culminated during the younger dryas period the present flow pattern with two mow core layers centred at 800 and 1300 m water depth was established between 7 5 and 5 5 ka

early middle pleistocene transitions an overview and recommendation for the defining boundary the early middle pleistocene transition c 1 2 0 5 ma sometimes known as the mid pleistocene revolution represents a major episode in earth history low amplitude 41 ka obliq uity forced climate cycles of the earlier pleistocene were replaced progressively in the later pleistocene by high amplitude 100 ka cycles these later cycles are indicative of slow ice build up and subsequent rapid melting and imply a transition to a strongly non linear forced climate system changes were accompanied by substantially increased global ice volume at 940 ka these climate transformations particularly the increasing severity and duration of cold stages have had a pro found effect on the biota and the physical landscape especially in the northern hemisphere this review assesses and integrates the marine and terrestrial evidence for change across this transition based on the literature and especially the following 17 chapters in the present volume orbital and non orbital climate forcing palaeoceanography stable isotopes organic geochemistry marine micropalaeontology glacial history loess palaeosol sequences pollen analysis large and small mammal palaeoecology and stratigraphy and human evolution and dispersal are all considered and a series of discrete events is identified from marine isotope stage mis 36 c 1 2 ma to mis 13 c 540 460 ma of these the cold mis 22 c 880 870 ka is perhaps the most profound however we here endorse earlier views that on practical grounds the matuyama brunhes palaeomagnetic chron boundary mid point at 773 ka with an estimated duration of 7 ka would serve as the best overall guide for establishing the early middle pleistocene subseries boundary

nepheloid layer distribution in the whittard canyon ne atlantic margin article i nfo article history the dynamics and distribution of nepheloid layers in multiple branches of the whittard canyon were observed during three hydrographic surveys carried out between 2011 and 2013 the sources of permanent and temporal variation of the layers were investigated seasonal variations in primary production at the surface were reflected in the nepheloid layers extending down in the water column particularly in the upper reaches of the canyon benthic nepheloid layers were observed along the canyon axes to depths greater than 2500 m a distance of 30 km intermediate nepheloid layers were detected as lateral extensions of the benthic nepheloid layer centredat 550m 850m 1150 mand1600m and stretching 20 25kmoff slope criticalandsupercriticalcon ditions for semidiurnal tide reflection were identified coinciding with the occurrence of intermediate nepheloid layers with other hotspots found at the boundaries of the permanent thermocline and mediterranean outflow water weak seasonal stratification during the survey in 2012 appeared to permit storm induced mixing at deeper water depths than expected altering the distribution of material in the nepheloid layers the dynamic conditions of the canyon encourage nepheloid layer formation with implications ensued for deposition rates and food supply to the unique communities that are found in the whittard canyon and likely other similar can yon systems

straightforward reconstruction of 3d surfaces and topography with a camera accuracy and geoscience application topographic measurements for detailed studies of processes such as erosion or mass movement are usually acquired by expensive laser scanners or rigorous photogrammetry here we test and use an alternative technique based on freely available computer vision software which allows general geoscientists to easily create accurate 3d models from field photographs taken with a consumer grade camera the approach integrates structure from motion sfm and multi view stereo mvs algorithms and in contrast to traditional photogrammetry techniques it requires little expertise and few control measurements and processing is automated to assess the precision of the results we compare sfm mvs models spanning spatial scales of centimeters a hand sample to kilometers the summit craters of piton de la fournaise volcano with data acquired from laser scanning and formal close range photogrammetry the relative precision ratio achieved by sfm mvs measurement precision observation distance is limited by the straightforward camera calibration model used in the software but generally exceeds 1 1000 i e centimeter level precision over measurement distances of 10s of meters we apply sfm mvs at an intermediate scale to determine erosion rates along a 50 m long coastal cliff seven surveys carried out over a year indicate an average retreat rate of 0 70 0 05 m a 1 sequential erosion maps at 0 05 m grid resolution highlight the spatio temporal variability in the retreat with semivariogram analysis indicating a correlation between volume loss and length scale compared with a laser scanner survey of the same site sfm mvs produced comparable data and reduced data collection time by 80

combining geomorphometry feature extraction techniques and earth surface processes research the way forward abstract in recent years the wealth of technological development revolutionised our ability to collect data in geosciences due to the unprecedented level of detail of these datasets geomorphologists are facing new challenges giving more in depth answers to a broad er range of fundamental questions across the full spectrum of the earth s and planetary processes this contribution builds on the existing literature of geomorphometry the science of quantitative land surface analysis and feature extraction translate land surface parameters into extents of geomorphological elements it provides evidence of critical themes as well as emerging fields of future research in the digital realm supporting the likely effectiveness of geomorphometry and feature extractions as they are advancing the theoretical empirical and applied dimension of geomorphology the review further discusses the role of geomorphometric legacies and scientific reproducibility and how they can be implemented in the hope that this will facilitate action towards improving the transparency and efficiency of scientific research and accelerate discoveries in geomorphology in the current landscape substantial changes in landforms ecosystems land use hydrological routing and direct anthropogenic modifications impact systems across the full spectrum of geomorphological processes although uncertainties in the precise nature and likelihood of changes exist geomorphometry and feature extraction can aid exploring process regimes and landscape responses taken together they can revolutionise geomorphology by opening the doors to improved investigations crossing space and time scales blurring the boundaries between traditional approaches and computer modelling and facilitating cross disciplinary research ultimately the exploitation of the available wealth of digital information can help to translate our understanding of geomorphic processes which is often based on observations of past or current conditions into the rapidly changing future

contourites and their relevance for mass wasting along the mid norwegian margin between about 12 and 4 3 ma slope parallel bottom currents dominated the neogene sedimentation on the slope of the mid norwegian margin and large scale sediment bodies accumulated to thicknesses up to 1000 m these bedforms are morphologically classified as sheeted and elongated mounded contourite drifts an increase in sediment supply from about 4 to 3 ma due to onshore uplift and glaciation resulted in a massive influx of downslope derived material onto the continental margin only on the voring plateau was contourite sedimentation little affected by this change in sedimentary style during the last 0 5 my contouritic deposits occurred also in the storegga area as 100 150 m thick infill drifts inside the scars of two palaeo slides r and s holocene post slide deposits in the scar of the storegga slide 8 2 ka have the typical morphological features and distribution of contourite drifts with the upslope limit at the lower base of the warm northward flowing north atlantic current at 500 700 m depth and the downslope limit at depths of approximately 1200 m detailed chronostratigraphy of the post slide sediments show relatively constant high sedimentation rates in the order of 1 2 m ky during the last 8000 years this is equivalent to the estimated rates for the older infill drifts the infill drifts consist mainly of clays with silty and sandy lamina and represents marine and glaciomarine conditions the main influence of contourite drifts on slope stability relates to their physical properties forming a more sensitive and brittle deposit than the glacial deposits and their exposure to downslope sedimentation in addition the potential for build up of excess pore pressure due to rapid loading from subsequent glacial depositions their seabed smoothing effect and great lateral extent make the contourite drift deposits particularly important for slope instability in this region

geomorphology of ona basin southwestern scotia sea antarctica decoding the spatial variability of bottom current pathways abstract ona basin the westernmost oceanic basin in the southern scotia sea is affected by the opposite flows of circumpolar deep water cdw and weddell sea deep water wsdw thus it represents a key location for exploring seafloor morphologies influenced by bottom currents the present study aims to capture the spatial arrangement of recent subsurface contourite features assuming a latitudinal influence of water masses and the interactions between along and downslope processes in order to contribute to the knowledge of regional deepwater flow pathways and to the sedimentary model of small sediment starved oceanic basins to this end the investigation combines an interpretation of multibeam bathymetry and parametric echo sounder seismic data complemented with hydrological data the distribution of morpho sedimentary features in ona basin reveals two major domains the southern margin of the basin can be regarded as a mixed hybrid system containing abundant sediment drifts with channels and contourite moats and a lateral continuity interrupted by downslope morphologies in contrast the northern abyssal setting comprises relatively homogeneous large sheeted drifts with superimposed sediment waves mounded drifts and several scattered erosive features likely reflecting the more distinct influence of deepwater contourite processes our work demonstrates that tectonic features in the southern basin control the interaction between deepwater along and downslope processes as the westward flow of the wsdw is deflected channelized and intensified along its westward route in the northern region the study indicates an overall clockwise rotation of the wsdw flow with the spatial and vertical variability of cdw and wsdw affecting the distribution of bottom current features around seamounts and or structural highs the results underscore the importance of sloping interphases in the water mass vertical structure the degree of basin confinement and the influence of local bathymetric elevations in sedimentation models of small sediment starved oceanic basins

a review of the physical oceanography of the mediterranean outflow abstract the physical oceanography of the mediterranean sea is reviewed with particular emphasis on the mediterranean outflow in the gulf of cadiz in this region the dense mediterranean water forms a high velocity bottom current that interacts strongly with the sea floor the major energy source for the plume comes from the release of potential energy as the plume descends the continental slope and the major energy sink is work against bottom stress which is as large as 4 pa where the plume begins to descend the continental slope in this region the current makes a nearly inertial turn that would otherwise appear to be steered by the underlying topography the mediterranean plume entrains the overlying north atlantic central water and thereby loses much of its density anomaly the mixed mediterranean water becomes neutrally buoyant in the lower portion of the north atlantic thermocline near cape st vincent there are then two preferred transport modes having somewhat different temperature and salinity whose distinct characteristics can be found far into the open north atlantic the temperature salinity and volume of the mediterranean water in the strait of gibraltar and in the gulf of cadiz appear to be roughly constant since modern measurements have been made the estimated westward transport of mediterranean water has gone down considerably as direct measurement techniques have been applied a recent estimate is that the westward transport of pure mediterranean water is only about a half a sv 1 sv 106 m3 s 1 the transport of mixed mediterranean water in the western gulf of cadiz is larger by about a factor of three or four because of the entrainment of north atlantic water

bottom current controlled sedimentation a synthesis of the contourite problem abstract an overview of the main items concerning deep bottom current controlled deposits is presented these include the definition of contourites their processes of deposition and facies characteristics contourite drift types and seismic patterns the interplay of turbidity and bottom current processes and the correlation between bottom current processes and global changes in climate sea level from this discussion several of the more significant problems are highlighted which we believe should be priority targets for future research 1 identification of contourites especially in ancient series where they are interbedded with turbidites and other facies 2 refinement of the numerous parameters used as tracers of palaeocirculation patterns 3 understanding the interaction between the different types of bottom currents and also between bottom current and other deep water processes 4 distinction in the sedimentary record between the effects of short time scale bottom current variations due to regional causes like benthic storms and geological scale current fluctuations related to climatic or astronomic control 5 understanding the control of glacial interglacial climatic cycles on the nature and rate of contourite deposition

modeling the topography of shallow braided rivers using structure from motion photogrammetry abstract recent advances in computer vision and image analysis have led to the development of a novel fully automated photogrammetric method to generate dense 3d point cloud data this approach termed structure from motion or sfm requires only limited ground control and is ideally suited to imagery obtained from low cost non metric cameras acquired either at close range or using aerial platforms terrain models generated using sfm have begun to emerge recently and with a growing spectrum of software now available there is an urgent need to provide a robust quality assessment of the data products generated using standard field and computational workflows to address this demand we present a detailed error analysis of sub meter resolution terrain models of two contiguous reaches 1 6 and 1 7 km long of the braided ahuriri river new zealand generated using sfm a six stage methodology is described involving i hand held image acquisition from an aerial platform ii 3d point cloud extraction modeling using agisoft photoscan iii georeferencing on a redundant network of gps surveyed ground control points iv point cloud filtering to reduce computational demand as well as reduce vegetation noise v optical bathymetric modeling of inundated areas and vi data fusion and surface modeling to generate sub meter raster terrain models bootstrapped geo registration as well as extensive distributed gps and sonar based bathymetric check data were used to quantify the quality of the models generated after each processing step the results obtained provide the first quantified analysis of sfm applied to model the complex terrain of a braided river results indicate that geo registration errors of 0 04 m planar and 0 10 m elevation and vertical surface errors of 0 10 m in non vegetation areas can be achieved from a dataset of photographs taken at 600 m and 800 m above the ground level these encouraging results suggest that this low cost logistically simple method can deliver high quality terrain datasets competitive with those obtained with significantly more expensive laser scanning and suitable for geomorphic change detection and hydrodynamic modeling