transversal and oblique structures at the serres de llevant thrust belt mallorca island the serres de llevant thrust and fold segment outcrops along the se coast of mallorca balearic isles spain and represents the eastern continuation of the external zones of the alpine betic range the structure of the serres de llevant consists mainly of northwest directed thrusts which involve a sedimentary series ranging in age from upper triassic to middle miocene the thrusts form a thrust system developed both by piggy back and out of sequence thrusting thrust sheets are imbricated to the se and to the sw and in the northern part also to the ne giving rise to a complex 3 d pattern the thrusts and related folds developed during the oligocene and the lower and middle miocene the thrust transport direction has been inferred from the stratigraphic facing directions of all mapped ramps and has been determined with the aid of other transversal structures the resulting transport direction is from se to nw n310e one of the most significant structural features of the serres de llevant thrust segment is the existence of several lateral and oblique structures these structures are ramps which display stratigraphic facing directions both to the ne and sw other lateral structures represented in the northern part of the thrust segment are tear and drop faults in the southern part kilometric scale oblique folds are exposed

analysing the topographic form of stratovolcanoes abstract the goal of this study is to explore ideal analytic functional forms that best fit the topographic shape of n 190 isolated stratovolcanoes from around the world using a stochastic model for the piling of lava flows to demonstrate one set of physical processes that give rise to a stratovolcano s topography we find that although the ideal form fits well for many stratovolcanoes there exist deviations from this shape particularly where the edifice is more protuberant than expected we explore sub surface factors such as the emplacement of magma beneath a volcano edifice that may be responsible for these deviations and estimate the relative contribution of dyke intrusions on the height and shape of a volcanic edifice versus the constructional piling of lava from this comparison we are able to gain more insight into the role of important subsurface physical factors such as chamber depth and total intruded volume we find that low basal ellipticity is a characteristic of nearly all volcanoes that fit the ideal stratovolcano form by fitting along each quadrant bisected by either a semi major or semi minor ellipse axis we find that the volcanoes chosen in this study fall into four groups 1 volcanoes that are axisymmetric and fit the ideal form well 2 volcanoes that are not axisymmetric but may be fit to the ideal form using different fitting parameters in each quadrant 3 volcanoes that have axisymmetric protuberant deviations in all quadrants and 4 volcanoes that have non axisymmetric protuberant deviations that are only present in a couple of quadrants we show that in some cases the non axisymmetry of volcanoes in category 2 may be understood as the result of the piling of eruptive products along a regional planar trend for edifices in categories 3 and 4 we model protuberant deviations as the result of a statistical distribution of elastic tensile dislocations representing dykes which emanate from a magma reservoir and cause uplift at the surface we support this interpretation of the excess topography in a few case studies where independent geologic and geophysical data corroborate our model results

a simple model for the formation of vegetated dunes a simple model for the dynamics of dunes associated with vegetation is proposed using the model the formation processes of transverse dunes parabolic dunes and elongated parabolic dunes are simulated according to two environmental factors i the amount of sand at the source ii the wind force the results have qualitative correspondence to the real counterpart and the simplicity of the algorithm and the consequent ease of handling this model provide us with wide applicability for the investigation of the complex interplay between vegetation and dunes copyright 2001 john wiley sons ltd

seismicity of the caldera making eruption of mount katmai alaska in 1912 the seismic activity associated with the century s largest eruption and caldera collapse at mount katmai alaska during june 1912 was poorly understood and is studied here in detail the epicenter of the large shock of 10 june was long thought to be 140 km northeast of mount katmai but it is relocated to be 12 km west of mount katmai near the novarupta dome origin times surface wave magnitudes ms and broadband body wave magnitudes mb are assigned to 50 new shocks from instrumentally observed data of more than 60 worldwide milne s and other seismological stations of 50 shocks detected 14 have ms 6 0 and greater and the largest is 7 0 both the frequency magnitude relation and the mb ms relation apparently exhibit normal appearance for the alaskan region the strong earthquakes were concentrated in the nights of 6 and 7 june it is inferred that the substantial collapse of mount katmai took place in these two nights the total energy released in seismic waves is 7 1 1015 j corresponding to the energy of a single shock with ms 7 4 the total seismic moment is estimated to be 1 4 1020 nm from ms values this total moment can be interpreted in terms of failures caused by the total volume change of 5 km3 this volume agrees well with the estimated volume of the caldera collapse which presumably took place in response to transfer of supporting magma from beneath mount katmai toward novarupta

wave beach and dune interactions in southeastern australia abstract a morphodynamic classification of surfzones beaches and dunes of the microtidal low to high energy southeast australian coast is presented the first section a waves and beaches briefly deals with the transformation of deep water wave energy as it crosses the shelf nearshore and surfzone depending on the deep water wave characteristics and shelf and inshore morphology resultant breaker wave energy may be high moderate or low and the accompanying beach surfzone morphodynamic state in fine to medium sand beaches either dissipative intermediate or reflective dissipative beaches have wide surfzones with shore parallel bar s and channel s and predominantly shore normal circulation intermediate beaches are characterised by rip circulation crescentic transverse bars and megacusps and reflective beaches by a barless surfzone and steep cusped or bermed beach each beach form has a characteristic level of beach stability zone of sediment storage and mode of beach and dune erosion landward aeolian sediment transport of swash deposited sand section b is dependent on the subaerial beach topography and the aerodynamic flow regime across that topography characteristic profile shapes are ascribed to each beach type dissipative intermediate and reflective aeolian sand transport rates are potentially highest on dissipative beaches moderate on intermediate beaches and lowest on reflective beaches these rates determine the potential size of foredunes which are correspondingly largest on dissipative beaches and smallest on reflective beaches the combination of mode and frequency of beach dune erosion rates of aeolian sand transport and foredune volume and morphology provide an explanation of the nature and morphology of landward occurring large scale dune systems dissipative beaches are frequently characterised by large scale transgressive dune sheets intermediate by a trend from large scale parabolic dune systems high wave energy to small scale blowouts low wave energy and reflective beaches by minimal dune development

aeolian granule ripple deposits namibia granule ripples are a common feature of most dunefields yet they have seldom been recognized in ancient deposits although granule ripples are common in erosional settings such as windward slopes of dunes or scour surfaces in interdunes they nevertheless migrate laterally and leave distinctive deposits that can be recognized in ancient rocks these deposits have characteristics of type b sand sheet deposits including poured in texture curving ripple trough tangential coarse grained foresets irregular silty layers well sorted coarse and fine layers either horizontal or within foresets and fine layers in ripple troughs wind tunnel experiments suggest that under low velocity wind conditions granule ripples grow to a significant degree as parasites dependent on saltation of fine sand grains whose impact moves the larger grains of the granule ripple although the depositional surface of granule ripples is commonly coated with a layer of coarse grains this is in most places only a few grains thick underlying deposits commonly have a poorly sorted or poured in texture this texture results from an admixture of fine grains that fall among the spaces between the larger grains during deposition

influence of high water levels on aeolian sand transport upper beach dune evolution on a macrotidal coast wissant bay northern france abstract aeolian sand transport measurements and detailed topographic surveys were carried out during 1 year along a macrotidal upper beach dune system experiencing rapid coastal retreat aeolian transport measurements coupled with wind records showed extreme spatial and temporal variability along a spatially limited upper beach sector analysis of wind velocity rainfall and water level showed that aeolian sand transport may occur all year long on the upper beach with the most energetic conditions occurring during winter and spring analysis of volume change revealed that aeolian sedimentation on the upper beach occurred only during the summer period while the rest of the year was characterised by upper beach and dune scarp erosion this erosion due to storm events combined with high water levels completely eliminated summer aeolian sand accumulation our results show that aeolian transport and upper beach dune evolution on this macrotidal beach is strongly controlled by the magnitude and frequency of occurrence of high water levels this study illustrates the fact that upper beach dune evolution cannot be completely understood and satisfactorily modelled if only potential aeolian sand transport is considered

sedimentary structures of cold climate coastal dunes eastern hudson bay canada a study of sedimentary structures of cold climate coastal dunes along eastern hudson bay canada showed that in areas of very sparsely vegetated surfaces tractional sedimentary processes are dominant while in partly and well vegetated areas grainfall deposition is the dominant sedimentary process alternating fine and coarse sand strata are characteristic of the vegetated foredune ridge coarse strata are interpreted to be mainly related to niveo aeolian deposition in poorly vegetated areas deformed strata associated with the melting of snow were preserved a vaguely stratified strata interpreted as a dimpled surface as well as coarse lenses with irregular basal contact were found such distinctive sedimentary structures may represent good indicators of cold climate conditions and could serve as criteria to identify aeolianites that may have been deposited in similar cold climate environments in palaeoenvironmental reconstructions

dynamics of the douro estuary sand spit before and after breakwater construction abstract the douro estuary sand spit nw portugal is an important natural defence against the impact of storm events aiming to improve navigation safety a breakwater was built to stabilise the spit in 2001 a monitoring programme was set up to understand the dynamics of the sand spit and later to evaluate breakwater efficiency on stabilising the spit s shape and volume nine years of periodic accurate 3d digital elevation models obtained from kinematic differential global positioning system surveys were used to assess spatial and temporal changes in the spit morphology before and after the breakwater construction temporal and spatial spit dynamics were further related to river discharge flows wave action and wind energy although the breakwater had a stabilising effect on most of the spit s area and volume it caused a clear change in the morphology of the spit s head and in the previously observed patterns of erosion and accretion before breakwater construction erosion was significantly correlated with extreme river discharge and wind conditions accretion was significantly correlated with extreme wind conditions and spit area and volume at 1 2 m elevation with extreme wave conditions after breakwater construction these correlations were not found but the eastern inland face of the spit and particularly its southern part became more susceptible to the observed extreme river discharge flows wave and wind conditions the instability in the se part of the spit may pose a threat to an existing local nature reserve furthermore before breakwater construction the spit often breached during severe floods favouring river discharges the strengthening of the spit after breakwater construction may reduce the likelihood of breaching and lead to more severe flood effects in the estuary

stratification and sedimentation in complex vegetated coastal dunes sable island nova scotia abstract a descriptive code for analysing the internal structure of vegetated coastal dunes is presented the code is based upon three elements grain size stratification and the nature of plant remains it is used in an analysis of the dunes on sable island nova scotia a description of the stratification within the older dunes of the island provides the basis for a genetic interpretation of the processes operating throughout their history particular importance is attached to the role of vegetation in deposition four phases of dune development each with distinct styles of stratification are recognized in the sable island dunes the first consists of tractional and grainfall deposition within very sparse vegetation the second phase is dominated by grainfall deposition through increasingly dense vegetation the third phase is represented by a paleosol finally the fourth phase consists of horizontal parallel and wavy laminated beds of loosely compacted finer sand which result from grainfall deposition through dense vegetation

sedimentology of cold climate aeolian sandsheet deposits in the askja region of northeast iceland active aeolian sandsheets cover an area of 270 km2 in the askja region of ne iceland the sandsheet is divided into i a deflationary upwind part that is characterised by deflation lags ventifacted boulder fields and restricted aeolian sand patches in the lee of obstacles ii an accumulating central part that is characterised by continuous aeolian sand cover up to 10 m thick where three scales of aeolian ripples are evident along with larger scale forms including longitudinal zibars and iii a downwind part that is currently subject to aeolian bypass with only localised accumulation occurring in topographic hollows between basaltic lava fields trains of aeolian granule megaripples are a characteristic landform of the downwind part of the sandsheet these sinuous crested oblique bedforms attain heights of 0 35 m and downwind spacings of 6 m they are composed principally of low density pebble grade pumice clasts and other reworked volcaniclastic detritus derived from the nearby askja volcanic centre the distribution of landforms across the sandsheet reflects a regional aeolian sediment budget that is controlled by dynamic interactions between glacial ice margin fluvial aeolian and volcaniclastic processes under the influence of a distinctive climatic regime sediment supply at the upwind sandsheet margin adjacent to the dyngjujokull glacier increases during summer periods when rates of glacial ablation are at a maximum longer term controls on sediment supply rate are determined by episodes of glacier surging and retreat and by periodic eruptions of volcaniclastic debris from the askja volcanic centre the availability of sediment for aeolian transport is controlled by the level of the groundwater table the depth and continuity of the permafrost layer in the proglacial area the degree of development of armoured pebble lags and freezing of the sandsheet surface during winter months the transport capacity of the wind varies on a seasonal basis with mean wind velocities and wind gustiness reaching a maximum during winter periods both winter and summer mean wind velocities have been steadily increasing since formal records began in 1969 the suite of aeolian landforms developed within the askja region as defined by sediment texture and composition and bedform scale morphology and spatial distribution reflects a special set of controlling circumstances which mean that the askja sandsheet deposits differ significantly from those described from elsewhere

effects of time dependent moisture content of surface sediments on aeolian transport rates across a beach wildwood new jersey u s a a one day field investigation on an unvegetated backbeach documents the importance of surface sediment drying to aeolian transport surface sediments were well sorted fine sand moisture content of samples taken in the moist areas on the backbeach varied from 2 9 to 9 2 per cent lack of dry sediment inhibited transport prior to 08 50 by 09 10 conspicuous streamers of dry sand moved across the moist surface barchan shaped bedforms 30 to 40 mm high and composed of dry sand moisture content 0 10 per cent formed where sand streamers converged the surface composed of dry sand increased from 5 per cent of the area of the backbeach at 09 50 to 90 per cent by 12 50 mean wind speeds were beetween 5 6 and 8 6 m s 1 at 6 m above the backbeach corresponding shear velocities were always above the entrainment threshold for dry sand and below the threshold for the moist sand on the backbeach measured rates of sand trapped by vertical cylindrical traps increased during the day relative to calculated rates the measured rate of sand trapped on the moist foreshore was higher than the rate trapped on the backbeach during the same interval indicating that the moist foreshore moisture content 18 per cent was an efficient transport surface for sediment delivered from the dry portion of the beach upwind measured rates of sand trapped show no clear relationship to shear velocities unless time dependent surface moisture content is considered results document conditions that describe transport across moist surfaces in terms of four stages including 1 entrainment of moist sediment from a moist surface 2 in situ drying of surface grains from a moist surface followed by transport across the surface 3 entrainment and transport of dry sediment from bedforms that have accumulated on the moist surface and 4 entrainment of sand from a dry upwind source and transport across a moist downwind surface 1997 john wiley sons ltd

u series measurements in tyrrhenian deposits from mallorca further evidence for two last interglacial high sea levels in the balearic islands the campo de tiro type section for the tyrrhenian ecostratigraphic beds of the balearic islands shows four indurated littoral conglomerates and beach rocks unconformably superimposed the lower two units 1 and 2 are separated by a thin layer of reddish continental silts both contain a typical eutyrrhenian fauna whereas a neotyrrhenian fauna characterizes the overlying units 3 and 4 thu measurements by thermal ionisation mass spectrometry on mollusk shells from these deposits yielded ages of 135 ka unit 1 117 ka units 2 and 3 and a scatter of ages around 100 ka unit 4 the stratigraphic relationships and thu data indicate i that uranium was uptaken by mollusks shells but arca sp each time during a relatively short early diagenetic interval before cementation ensured a fair closure of the radioactive system ii two high sea stands characterized the last interglacial isotopic substage 5e of the balearic islands area iii the duration of this episode was 17 ka and iv the change in faunal assemblages and disconformity observed between units 2 and 3 are due to fluctuations in sea level and surface water conditions which occurred during the second high sea level episode of the last interglacial

constraints on unrest in the tolbachik volcanic zone in kamchatka prior the 2012 13 flank fissure eruption of plosky tolbachik volcano from local seismicity and gps data abstract a new fissure eruption began on 27 november 2012 on the southern slope of plosky tolbachik volcano which is located in central kamchatka russia and is part of the klyuchevskoy volcano group we analyzed the displacement of the earth surface and the seismicity during several months before the eruption onset according to seismic and gps data the eruption was preceded by about 4 5 months july november 2012 of synchronous crustal deformation and seismicity the seismic anomaly comprises low energy level seismicity mainly m 1 2 2 3 under plosky tolbachik volcano at a depth of less than 5 km in the 2 3 weeks immediately preceding the eruption the rate of seismicity and the amount of radiated seismic energy exceeded the long term average values 2000 2011 by more than 40 times the deformation anomaly was recorded by displacement of the gps points at distances from 20 to 60 km to the north of tolbachik the principal axis of the compressive strain was approximately directed towards the tolbachik eruption site the permanent gps network detected radial compression and tangential stretching the compressive strain reached about 10 7 prior to eruption onset the comparable duration of seismic and deformation anomalies 4 5 months before the eruption is consistent with a common origin connected to magma rising from depth and is interpreted as indicating that they were medium term precursors to the eruption data recorded during this unrest episode of the tolbachik volcanic zone will contribute to understanding of the reawakening of volcanic activity in this region and others worldwide with similar characteristics

evaluation of the egnos service for topographic profiling in field geosciences abstract consumer grade global positioning system gps receivers are commonly used as a tool for data collection in many fields including geosciences one of the methods for improving the gps signal is provided by the wide area differential gps wadgps which uses geostationary satellites to correct errors affecting the signal in real time this study presents results of three experiments aiming at determining whether the precision of field measurements made by such a receiver garmin gpsmap 62s operating in either the non differential and the wadgps differential mode is suitable for characterizing geomorphological objects or landforms it assumes in a typical field work situation when time cannot be devoted in the field to long periods of stationary gps measurements and the precision of topographic profile is at least as important as if not more than positioning of individual points the results show that with maintaining some rules the expected precision may meet the nominal precision the repeatability coherence of topographic profiles conducted at low speed 0 5 m s 1 in mountain terrain is good and vertical precision is improved in the wadgps mode horizontal precision is equivalent in both modes the gps receiver should be operating at least 30 min prior to measuring and should not be turned off between measurements that the user like to compare if the gps receiver needs to be reset between profiles to be compared the measurement precision is higher in the non differential gps mode following these rules may result in improvement of measurement quality by 20 to 80

recent shoreline mobility and geomorphologic evolution of macrotidal sandy beaches in the north of france abstract this paper examines shoreline mobility and sediment budget conditions on a sandy macrotidal coast with a well developed foredune aerial photographs and bunker archaeology covering the last 50 years were analysed in order to determine the meso scale evolution of le touquet beach in northern france both methods show that shoreline retreat has been negligible or very slow and has been accompanied by an elevation of the foredune dgps cross shore profiles show a balanced sediment budget over the last 7 years only a slight change of the beach face profile 0 2 0 5 m rise or fall was observed while the foredune exhibited a sharper change the french coast of the eastern english channel differs from that of the french atlantic coast which is currently being strongly eroded the balanced sediment budget of the former is attributed to sand inputs from nearshore banks which compensate exports due to longshore drift and to foredune development

in search of pollentia s southern harbour geoarchaeological evidence from the bay of alcudia mallorca spain the roman city of pollentia was founded on the north eastern coast of mallorca balearic archipelago after the roman conquest of the island in 123 bce there is evidence that the city had two harbours a small harbour located to the north whereas the main harbour was located to the south of pollentia our study focuses on the southern harbour on a coastal plain in proximity to the ancient city four sedimentary cores were taken and bio sedimentological analysis was performed here we describe the palaeogeographical changes in this area evolving from an open lagoon environment between ca 3200 and ca 500 cal years bce to a semi enclosed lagoon during roman times progressively the lagoon became silted and was isolated from the sea by the development of a large sand spit probably during the second half of the first millennium ce we also discuss the water depth linked to the palaeosea level which is important in defining the possible ancient harbour location

foredunes and blowouts initiation geomorphology and dynamics this paper reviews the initiation dynamics geomorphology and evolution of incipient foredunes established foredunes and blowouts incipient foredunes may be initiated in a variety of ways leading to the formation of ramps terraces or ridges depending on progradation rates vegetation type and cover sediment transport rates and scale of erosional processes vegetation cover morphology growth rates and types combine with aerodynamic processes to determine dune and swale morphology established foredunes are classified into five morpho ecological types and the flow behaviour over two types is detailed a new model of foredune evolutionary paths at various possible time scales is presented blowout initiation dynamics and sediment transport and evolution is examined throughout the review the gaps in present understanding of dune processes and a range of ideas for new research possibilities are provided

shoreline evolution of the holland coast on a decadal scale the decadal evolution of the dunefoot position along 120 km of the holland coast is analysed firstly a new definition of dunefoot is introduced based on hydrodynamic and morphologic considerations which is not affected by local and instantaneous processes occurring immediately before the bathymetric survey the dunefoot evolution over decadal scales indicates the existence of spatial and temporal oscillations in the shoreline position with magnitudes of 2 3 km length and a periodicity of 4 15 years two main controlling factors of this behaviour are identified 1 influence of sub aqueous bar systems and 2 changes in the storm wave conditions reaching the coast although the precise controlling processes of the relation between the dunefoot and the subaqueous profile still remain unclarified we introduce the concept that the development of a morphological bar cycle requires a fixed amount of time integrated forcing that is proportional to the cumulative effect of storm waves beach mobility along the holland coast on decadal scales 10 20 m is similar or lower than mobility introduced by storms or by seasonal cycles however it is important to consider these changes for the possible implications on the local vulnerability of the coast to extreme events copyright 1999 john wiley sons ltd

development and setting of the alcudia bay beach dune system mallorca spain abstract the beach dune system of alcudia bay is located in the north of the island of mallorca the system includes both simple and compound parabolic dunes formed by n to nne winds and is made up of two dune areas with different dynamics 1 the northern area where despite the fact that the source of beach sediment is from the south dunes are formed by northerly winds and develop a narrow and linear barrier which separates a marsh from the bay and 2 the southern area where complex parabolic dunes formed by north northeasterly winds prograde south southwest landward extending several kilometers inland the broad pattern of the dunefield size is limited to the southeast by a mountain range and to the west by the effects of a topographic corridor oriented north south which channels the prevailing northerly wind causing a southward dune progression and limiting the westward extension of the dunefield

seismicity and crustal deformation preceding the january 1996 eruptions at karymsky volcanic center kamchatka two explosive eruptions occurred on 2 january 1996 at karymsky volcanic center kvc in kamchatka russia the first dacitic from the central vent of karymsky volcano and the second several hours later from karymskoye lake in the caldera of akademia nauk volcano the main significance of the 1996 volcanic events in kvc was the phreatomagmatic eruption in karymskoye lake which was the first eruption in this lake in historical time and was a basaltic eruption at the acidic volcanic center the volcanic events were associated with the 1 january ms 6 7 mw 7 1 earthquake that occurred at a distance of about 9 17 km southeast from the volcanoes just before the eruptions we study the long term 1972 1995 and short term 1 2 january 1996 characteristics of crustal deformations and seismicity before the double eruptive event in kvc the 1972 1995 crustal deformation was homogeneous and characterized by a gradual extension with a steady velocity the seismic activity in 1972 1995 developed at the depth interval from 0 to 20 km below the akademia nauk volcano and spread to the southeast along a regional fault the seismic activity in january 1996 began with a short sequence of very shallow microearthquakes m 0 beneath karymsky volcano then seismic events sharply increased in magnitude up to mb 4 9 and moved along the regional fault to the southeast culminating in the ms 6 7 earthquake its aftershocks were located to the southeast and northwest from the main shock filling the space between the two active volcanoes and the ancient basaltic volcano of zhupanovsky vostryaki the eruption in karymskoye lake began during the aftershock sequence we consider that the ms 6 7 earthquake opened the passageway for basic magma located below zhupanovsky vostryaki volcano that fed the eruption in karymskoye lake

erratum multiple origins of linear dunes on earth and titan nature geoscience 2 653 658 2009 published online 16 august 2009 corrected after print 24 january 2010 in the version of this article originally published one of the data points in fig 3 was incorrect and should have been as shown here this error has been corrected in the html and pdf versions of the article

grain size and compositional trends of sediments from posidonia oceanica meadows to beach shore sardinia western mediterranean abstract inputs of biogenic carbonate sediment from posidonia oceanica seagrass meadows to four beaches of the sinis peninsula sardinia western mediterranean were evaluated beach and continental shelf sediment samples were analysed for grain size distribution and composition biogenic vs siliciclastic in order to identify the provenance of beach sediments and sediment transport pathways seabed mapping was carried out in order to identify the distribution of meadows and sediment deposits offshore shelf sediments were collected in unvegetated sites and in p oceanica meadows sediments from unvegetated sites were coarse sands and gravel mainly siliciclastic biogenic carbonate content is 3 7 sediments from p oceanica meadows were coarse sand mainly biogenic carbonate contents varying between 60 and 90 beach sediments showed bimodal grain size distribution 59 of samples resulting from mixing of coarser siliciclastic with finer biogenic materials in variable proportions biogenic carbonate contents in beach sediments range from 0 to 90 reaching the highest values in offshore samples analysis of grain size and compositional trends from shelf to beach sediments highlighted that the latter originate from two different sources erosion of granitic outcrops providing the siliciclastic component and export of sediments from p oceanica meadows providing biogenic material p oceanica meadows also influence shore by contributing towards maintaining the beach sediment budget

sediment supply from shoreface to dunes linking sediment transport measurements and long term morphological evolution a significant problem in current coastal research is the understanding of linkages between morphological phenomena occurring on different temporal and spatial scales morphodynamic processes in the nearshore typically exhibit nonlinear behaviour and consequently phenomena which occur on short temporal event scales as e g observed during field experiments have generally been difficult to upscale to provide an understanding of the long term behaviour of the coast on the time scale of seasons or decades this paper documents a persistent onshore migration of nearshore bar features over a period of 3 decades using a set of cross shore profile surveys from a barrier on the danish north sea coast the observed behaviour is consistent with experimental data obtained during weeklong field campaigns when sediment transport and bar migration were found to be landward directed during high energy dissipative conditions hydrodynamic and sediment transport processes leading to onshore bar migration and eventually welding of the bars are documented to provide an explanation for the observed long term evolutionary trends in addition bar welding and the resulting intertidal bar formation represent an onshore sediment storage which is subsequently available for aeolian transport observations on aeolian sediment transport indicate that transport rates and sediment supply to the foredunes critically depend on the presence of dry sand sources as represented by well drained intertidal bars measurements of long term accretion rates in foredunes indicate that volumes deposited on the crest and lee slope of the dunes are in reasonable correspondence with volumes supplied to the subaerial beach through the process of bar welding hence the data suggest that a persistent onshore directed sediment supply occurs from the shoreface across the surf and intertidal zones and into the dunes of the investigated barrier

short term beach dune sand budgets on the north sea coast of france sand supply from shoreface to dunes and the role of wind and fetch abstract three experimental plots covering the transition from the upper beach to the dune on the north sea coast of france were monitored at various intervals over a period of 18 24 months via high resolution terrain surveys in order to determine inter site sand budget variability as well as patterns and processes involved in sand exchanges between the upper beach and dune the wind regime consists of a fairly balanced mix of moderate 80 of winds are below 8 m s onshore offshore and shore parallel winds sustained dune accretion over several years depends on the periodic local onshore welding of shoreface tidal banks that have developed in the storm and tide dominated setting of the southern north sea the only site where this has occurred in the recent past is calais where bank welding has created a wide accreting upper beach sand flat at this site significant sand supply from the subtidal sand bank reservoir to the upper beach flat occurred only once over the 18 month survey following a major storm the bulk of the sand deposited over this large flat is not directly integrated into the adjacent embryo dunes by onshore winds but is progressively reworked in situ into developing dunes or transported alongshore by the balanced wind regime thus resulting in alongshore stretching of the embryo dune system the leffrinckoucke site near belgium shows moderate beach dune mobility and accretion while the wissant site exhibits significant upper beach bedform mobility controlled by strong longshore currents that result in large beach budget fluctuations with little net budget change to the detriment of the adjacent dunes accretion at these two sites which are representative of the rest of the north sea coast of france is presently constrained by the absence of a shore attached sand bank supply reservoir while upper beach dune sand exchanges are further limited by the narrow wave affected upper beach the intertidal morphology of bars and troughs which segments the aeolian fetch and the moderate wind energy conditions the balanced wind regime limits net sand mobilisation in favour of either the beach or the dune and may explain the relatively narrow longshore morphology of the dune ridges bounding this coast

variations in the response of the dune coast of northern france to major storms as a function of available beach sediment volume a series of airborne topographic lidar data were obtained from may 2008 to january 2014 over two coastal sites of northern france bay of wissant and east of dunkirk these data were used with wind and tide gauge measurements to assess the impacts of storms on beaches and coastal dunes and particularly of the series of major storms that hit western europe during the fall and early winter of 2013 our results show a high variability in shoreline response from one site to the other but also within each coastal site coastal dune erosion and shoreline retreat occurred at both sites particularly on the coast of the bay of wissant where shoreline retreat up to about 40 m was measured however stability or even shoreline advance were also observed despite the occurrence of an extreme water level with a return period 100 years during the storm xaver in early december 2013 comparison of shoreline change with variations of coastal dune and upper beach volumes revealed only weak relationships our results nevertheless showed that shoreline behavior seems to strongly depend on the initial sediment volume on the upper beach before the occurrence of the storms according to our measurements an upper beach volume of about 30 m3 m 1 between the dune toe and the mean high water level is sufficient at these sites to protect the coastal dunes from storm waves associated with high water levels with return periods 10 years the identification of such thresholds in terms of upper beach width or sediment volume may represent valuable information for improving the management of shoreline change by providing an estimate of the minimum quantity of sand on the upper beach necessary to ensure shoreline stability in this region copyright 2016 john wiley sons ltd

coastal aeolian dune development solheimasandur southern iceland abstract a coastal aeolian dune field on the distal parts of solheimasandur southern iceland is currently undergoing active construction ongoing sand deflation in the foreshore is demonstrated by the preservation of sand ridges in the downwind lee of obstacles while a backshore sandsheet is characterised by actively accumulating long wavelength wind ripples the main region of aeolian accumulation is in the immediate backshore where sand has accumulated to a thickness of up to 8 m and is largely stabilized by vegetation surrounding interdune areas have undergone repeated flooding by fluvial incursions from the adjacent jokulsa river and are characterised by mud drapes which lap against the lower flanks of neighbouring dunes widespread sand adhesion structures testify to the often damp nature of the substrate over 1200 vegetated and stabilized dunes nebkhas occupy a 5 km 2 area of wind deflated gravel sandur plain downwind from the main site of aeolian accumulation the nebkhas show strong relationships between plan form shape and height indicating that they have attained equilibrium morphology for the prevailing climatic conditions within the nebkha field dunes demonstrate a predictable downwind decrease in height spatial concentration and degree of sand stabilization a time series of aerial photographs documents the temporal evolution of the dune field and demonstrates that aeolian accumulation commenced about 1940 and has been ongoing to the present day prior to 1940 repeated outburst floods associated with catastrophic lake drainage events from the solheimajokull glacier 8 km inland were of sufficient magnitude to repeatedly destroy any incipient aeolian bedforms that developed although strong onshore winds and high rates of sediment supply promote aeolian sediment transport dune field development is rare in humid boreal and sub arctic climates as encountered in southern iceland because the availability of sediment for aeolian transport is usually severely limited by damp substrate conditions thus the airflow tends to be undersaturated with respect to its potential sand transporting capacity and dune construction can only occur because of the stabilizing influence of vegetation

a general framework for modeling sediment supply to coastal dunes including wind angle beach geometry and fetch effects a series of spatially explicit equations are derived that form the foundation of a modeling framework that provides insight into how the interaction of the fetch effect and angle of wind approach leads to tradeoffs that govern the magnitude of aeolian sediment transport across beaches of different geometry the spatial distribution of sediment transport rate per unit width at any point on the beach is shown to vary predictably as a function of wind angle critical fetch and beach geometry and this has evident implications for the total volume and distribution of sediment transport into the dunes behind the beach as well as the proportion of sediment lost from the beach dune system at the downwind margin as the wind field shifts from onshore shore perpendicular to oblique shore parallel approach angle total sediment transport rate across a dune line segment will reflect a tradeoff between transport reduction because of the cosine effect and transport enhancement because of potentially longer fetch distances traversed by the wind prior to encountering the dune line this tradeoff is most evident on long narrow beaches when beach width is less than the critical fetch for such beaches and with onshore winds the total sediment transport rate across the dune line will be less than that predicted for a wide beach because of the constraint imposed by the fetch effect however as the angle of wind approach becomes oblique the available fetch becomes progressively longer transport limitations imposed by the fetch effect are negated and transport enhancement across the dune line is to be expected with very large angles of wind approach the cosine effect dominates the interaction and transport reductions across the dune line occur until the wind is shore parallel and sediment supply to the dunes ceases altogether this sequence of adjustments and tradeoffs were only partially understood prior to this study and yet they form the foundation of coastal dune modeling the framework proposed in this paper serves to place future studies of process form interaction in beach dune systems on a robust theoretical foundation it also facilitates the testing of various alternative hypotheses regarding the uneven spatial and temporal distribution of dune height and growth rate in coastal environments

environmental controls on coastal dune formation skallingen spit denmark abstract many coastal dune systems in western europe were emplaced during the little ice age lia the formation of such dune fields has generally been ascribed to a combination of low sea level and strong winds during that time period providing a supply of sand from the exposed shoreface and sufficient wind energy to transport this sand landward however little information exists on the processes that controlled sediment supply to the beach and why this onshore supply was initiated at all in this contribution we consider the origin and development of older dune fields on a barrier spit complex skallingen located in the northern part of the danish wadden sea maps and new data on dune litho and chrono stratigraphy the latter based on osl dating allow a precise estimate of the initiation and termination of dune emplacement dune formation at skallingen started at a relatively late stage of the lia and it can be temporally correlated with a phase of relative sea level rise in north western europe and with a high frequency of storm surges along the danish west coast these are the conditions during which nearshore bars currently migrate onshore across the shoreface off skallingen the bars eventually merge with the beach and constitute a source of sand for modern foredune accretion it is probable that the onshore bar migration occurred under similar conditions in the past and the migration was triggered or enhanced by the sea level recovery from the mid lia low stand and the associated frequent storm surge activity consequently at skallingen onshore sand supply was caused by marine rather than aeolian agents this supply provided the basis for subsequent dune formation indications are however that the sediment supply to the beach dunes was a factor of 2 3 larger in the past dune aggradation eventually ceased around 1900ad because of dyke construction hence the association between dune formation and sea level surge variation at skallingen is somewhat contrary to other statements of coastal dune development during the lia in north western europe

temperate carbonates on a modern low energy isolated ramp the balearic platform spain abstract this paper presents a depositional model for a temperate low energy carbonate ramp based on descriptive studies of five areas around the balearic islands of mallorca and menorca this low energy ramp differs significantly from other present day temperate carbonate platforms that are primarily high energy open shelves it is characterized by the following lithofacies from shore to basin 1 lagoon 2 barrier island 3 shallow subtidal 4 inner ramp 5 middle ramp and 6 distal ramp subaqueous carbonate dunes are present near slope breaks off menorca and cabrera but they are not representative of the entire ramp balearic ramp sediments differ in composition texture biology and degree of cementation from those on modern low energy tropical ramps balearic ramp carbon tes lack ooids and peloids hermatypic coral buildups and calcareous green algae except in one restricted bay where halimeda is relatively common red algal sands and gravels extend to depths of up to 90 m and are coarser than their strandplain equivalent lime sands skeletal allochems consist of the bryomol rhodalgal association marine cementation is rare and the carbonate fraction of deep water muds is mainly mg calcitic and calcitic in composition aragonite is rare except for the red alga peyssonnelia which is composed of aragonite it is neither a dominant skeletal constituent nor common as a cement the mediterranean sea off mallorca and menorca is a low energy temperate oligotrophic clear water environment the depositional model for the region is an isolated platform configured as a homoclinal ramp ancient counterparts of the balearic ramp are present in the neogene of the mediterranean tethys and the paratethys and though the constituents of fossil assemblages vary with time the biota of the balearic ramp such as bryozoans red algae echinoderms and mollusks ranges from the paleozoic era to the present echinodermal bryomols passing to basinal muds on carbonate ramps are particularly characteristic of the early carboniferous in north america and europe this suggests that the balearic islands temperate ramp may be more representative of some ancient carbonate sequenc s than either temperate high energy open shelves or tropical ramps in the present oceans

new data on the pleistocene of mallorca abstract stratigraphic geomorphologic and isoleucine epimerization studies at 15 sites in mallorca define four aminozones a c e and f g of increasing age that are related to transgressive regressive marine cycles from the holocene to the mid pleistocene calibration of aminozone e glycymeris aile ile mean from all sites 0 41 0 03 n 38 is provided by a 129 7 ka u series coral age on cladocora caespitosa from son grauet of the younger aminozones a relates to the holocene transgression and aminozone c to a mid to late isotopic stage 5 event 90 15 ka revealed only by supralittoral eolianites assigning an age to the older poorly resolved aminozones f and g called f g in this case is uncertain without supporting radiometric data but an age of 180 ka can be assigned to these aminozone s f g based on a kinetic model and other examples in the mediterranean several deposits previously dated u series molluscs between 75 and 300 ka appear to belong to the last interglacial complex stage 5 and aminozone e a proposed revision of the positive sea level history of mallorca shows multiple minor oscillations during the major last interglacial cycle stage 5 and two mid pleistocene sea levels one lower than present and the other at about 14 m a s l

seismic hazard of volcanic activity abstract seismic activity is a common feature of volcanic eruptions the majority of volcanic earthquakes are small their magnitudes do not exceed 2 or 3 at the same time significant moderate size and large volcanic earthquakes may also occur the study of 28 significant m w 4 5 earthquakes associated with volcanic eruptions of 20th century allowed us to formulate the following results about seismic hazard of volcanic activity 1 during the 20th century only three large m w 7 0 earthquakes directly associated with volcanic eruptions in the world were recorded 2 the maximum magnitude m w was estimated to be 5 4 for earthquakes related to central eruptions 7 0 for caldera collapse 5 9 for central eruptions accompanied by flank and or fissure eruptions 7 1 for flank and or fissure eruptions without central eruptions and 5 9 for submarine eruptions for seismicity just before the eruption the maximum magnitude of earthquakes was estimated to be m w 7 1 for seismicity at the initial stage of eruption m w 7 0 for paroxysmal stage of eruption m w 5 6 and for final stage of eruption m w 6 1 3 it was shown that the recurrence time of eruptions of the same type of volcano associated with significant m w 4 5 earthquakes was more than 100 years for 86 of events studied

the effect of wind gusts moisture content and fetch length on sand transport on a beach this paper reports on an analysis of instantaneous sediment transport in relation to wind gusts moisture content and fetch length from a field study carried out at skallingen denmark wind speeds were measured with cup anemometers and instantaneous sediment transport with vertical traps coupled to electronic balances moisture content was measured gravimetrically using samples taken along a beach profile at intervals of 1 to 2 h sediment transport and wind speeds were sampled at 1 hz and a 5 s running mean was used to smooth the data from the trap because of limitations of the balance resolution three measures of the threshold of sediment motion the intermittency threshold minimum threshold and maximum threshold were explored using data from five runs carried out on october 26 2000 the intermittency threshold and maximum threshold were largely insensitive to wind speed but varied spatially along the fetch distance the minimum threshold increased significantly with increasing mean wind speed as a result of reduced time for drying of the surface layer examination of time series for instantaneous wind speed and sediment transport for a number of runs on october 26 and november 6 2000 showed close agreement between fluctuations in wind speed and fluctuations in sediment transport cross spectral analysis of instantaneous wind speed and sediment transport for one run on each day where there was continuous transport showed high coherence between the two variables over a range of frequencies from 0 2 hz to 0 01 hz plots of all non zero instantaneous sediment transport values versus wind speed show considerable scatter in general transport rates are highest for traps located further from the upwind non erodible boundary i e along the fetch best fit power relationships show r2 values generally ranging from 0 4 to 0 6 and exponents ranging from 4 5 to 6 94 i e much higher than the traditional value of 3 found in most transport equations traps located close to the upwind boundary had lower r2 values and exponents 2 5

influences of eolian and pedogenic processes on the origin and evolution of desert pavements well developed desert pavements are present above eolian deposits that mantle flows of the cima volcanic field located in the mojave desert california soil stratigraphic data and geochemical data demonstrate that eolian and pedogenic processes play major roles in the evolution of these pavements eolian dust 1 accelerates mechanical fragmentation of flow rock providing the source material for pavements and 2 accumulates slowly below basaltic colluvium in flow depressions eventually promoting development of cumulate soils below the evolving stone pavement an increase in dust flux during the holocene has raised ancient pleistocene pavements as much as 20 cm above the former land surface the results of our studies demonstrate for the first time that most desert pavements do not form by deflation by overland flow or by upward migration of stones through a slowly formed clayey argillic horizon desert pavements are born and maintained at the surface

sediment accumulation rates west of the mid atlantic ridge 35 n abstract although carbonate curves have a long history of use for temporal correlation only limited agreement concerning the reasons for down core carbonate variations has been reached in this study these variations are examined by analyzing absolute accumulation rates of both carbonate and terrigenous sediment components carbonate content was determined in nine cores from approximately 3000 5000 m water depth down core variation in carbonate was correlated to an oxygen isotope curve to establish a down core time stratigraphy weight percent carbonate carbonate accumulation rate and terrigenous sediment accumulation rate were plotted as a function of water depth and time 0 130 000 yrs b p the weight percent carbonate plot indicates that carbonate content decreases with increasing water depth however the carbonate accumulation rate data demonstrates that this decrease in weight percent carbonate does not result from a decrease in the carbonate accumulation rate in the deeper cores the accumulation rate of carbonate actually increases in these deep cores the increase in carbonate accumulation rate is offset by a larger increase in the accumulation rate of terrigenous sediment resulting in a decrease in weight percent carbonate high accumulation rates of both carbonate and terrigenous sediment in cores below 4250 m appears to result from transport and redeposition of sediment most of the carbonate sediment deposited in these deep cores appears to be derived from shallow areas of the mid atlantic ridge mar the terrigenous sediment probably results from deposition by deep currents

coastline orientation aeolian sediment transport and foredune and dunefield dynamics of mocambique beach southern brazil abstract this paper examines the role of coastline orientation on foredune and dunefield development at mocambique beach southern brazil the beach displays significant alongshore variations in exposure to the prevailing winds and waves grain size beach surfzone morphodynamic type foredune volume and type and dimensions of the holocene dune systems two wind analyses and calculation of aeolian drift potentials were carried out one based on 1 year of wind record and another based on a record of 34 years monthly topographic surveys of beach and foredunes on 5 profiles along mocambique beach were conducted over one year to obtain data on beach mobility and width aeolian sediment transport and foredune development southerly winds dominate and aeolian sediment supply is minimal in the south moderate in the central portion and high in the northern portion of the embayment the relationship between actual sediment supply foredune building and potential sediment supply is relatively poor over one year due to factors such as beach type and mobility beach moisture levels rainfall storm surge and wave scarping the intermediate term 34 year record indicates a strong relationship between foredune size and volume winds and shoreline orientation foredune volume is minimum in the southern part of the beach and greatest in the northern part of the beach the holocene barrier and dunefield development also reflects the long term control of shoreline orientation and increasing longshore gradient in exposure to southerly winds for the last 6000 7000 years a small foredune developed in the southern portion parabolics and small transgressive dunes in the central portion and a large scale transgressive dunefield in the northern portion

deformation patterns magma supply and magma storage at karymsky volcanic center kamchatka russia 2000 2010 revealed by insar abstract under a complex geological region influenced by the subduction of the pacific plate kamchatka peninsula is one of the most active volcanic arcs in the pacific rim due to logistical difficulty in instrumentation shallow magma plumbing systems beneath some of the kamchatkan volcanoes are poorly understood insar offers a safe and quick method for monitoring volcanic deformation with a high spatial resolution in this study a group of satellite radar interferograms that span the time interval from 2000 to 2010 shows eruptive and non eruptive deformation at karymsky volcanic center kvc kamchatka russia all the interferograms provide details of the activity around the kvc during 2000 2010 as follows 1 from 2000 to 2004 the karymsky an akademia nauk area deflated and the ms maly semyachik area inflated 2 from 2004 to 2006 the karymsky an area deflated with ongoing eruption while the ms area subsided without eruption 3 from 2006 to 2008 as with 2000 2004 the karymsky an area deflated and the ms area inflated 4 from 2008 to 2010 the karymsky an area inflated up to 3 cm and the ms area subsided point source models suggest that two magma reservoirs provide a good fit to the observed deformation one source is located beneath the area between karymsky and an at a depth of approximately 7 0 km and the other one is situated beneath ms at a depth of around 5 8 km synchronous deformation patterns suggest that two magma systems are fed from the same deep magma source and connected by a fracture zone the insar results are consistent with gps ground deformation measurements seismic data and petrological constraints

the superficial sediments of the english channel and its western approaches the english channel and its western approaches constitute a 700 km long epicontinental sea located in a temperate environment and in a tectonic setting where subsidence is minimal a sedimentological survey of this region reveals quite distinct provinces a central sector western channel where predominantly bioclastic sediments are widely represented bounded by two mainly terrigenous rich zones the outer terrace of the celtic sea and the eastern channel lateral sedimentary variations of decreasing grain size are interpreted in terms of current velocity patterns the various types of such sequences may relate to the degree of mixing of older lithoclastic sediments with the holocene bioclastic supply a scenario for the evolution of the recent sedimentation of this epicontinental sea is presented starting from a permanent marine zone at least since the wurm period that bounds the bay of biscay the holocene transgression progressed over the english channel in the western channel earlier terrigenous deposits were gradually overlapped by bioclastic sediments that originated on the pre mesozoic rocky substratum and which were particularly extensive off the armorican massif in the subsequently submerged eastern channel the pre holocene clastic source has undergone comparatively less modification and still crops out in most of the area with the opening of the straits of dover at about 9000 yr bp submersion was complete and new hydrodynamic conditions developed as the eustatic level stabilized the present sediment distribution is in harmony with the hydrodynamic setting except on the southern rise of the celtic sea where both morphology and sedimentary patterns still largely reflect pre holocene conditions resume la mer de la manche et ses approches occidentales constituent une plateforme epicontinentale qui s etend suivant un axe ne sw d environ 700 km depuis le pas de calais jusqu au rebord continental c est un milieu sedimentaire de climat tempere a subsidence negligeable et a faible taux de sedimentation la couverture de depots meubles est mince quelques metres en general sauf au niveau des bancs sableux et des paleovallees souvent comblees s alluvions anciennes la repartition des sediments superficiels est essentiellement controlee par les courants de maree particulierement forts le long des cotes armoricaines et en manche centrale en manche occidentale un important gradient de vitesses decroissantes se developpe du sud est au nord ouest les houles s exercent principalement sur la frange cotiere ou leur action devient dominante dans l ensemble les depbts fins sont rares et concentres dans les baies et les estuaires ou les suspensions se decantent par contre les sediments graveleux a caillouteux sont largement repartis une opposition nette se dessine entre une province orientale surtout terrigene et une province occidentale au materiel bioclastique abondant presentant un gradient de dispersion en direction du sud ouest ces caracteres morphologiques et sedimentaires du milieu sont fortement marques par son histoire quaternaire notamment par la derniere oscillation marine un schema de mise en place et d evolution du modele sedimentaire au cours du quatenaire recent est propose partant de la zone en permanence submergee durant le wurm la transgression holocene progressa sur la manche le pas de calais s ouvrit vers 9000 bp et peu a peu les conditions hydrodynamiques actuelles se mirent en place sous un climat devenu tempere progressivement les depots terrigenes anciens furent contamines par du materiel bioclastique holocene

seasonal morphological response of an open sandy beach to winter wave conditions the example of biscarrosse beach sw france abstract 18 months of at least bi weekly topographic surveys have been conducted on a 700 m stretch of the meso to macro tidal biscarrosse beach france here we focus on the impact of the short term dynamics of the beach a few days on the seasonal winter response of the beach the beach was surveyed intensively during two winter seasons and the results indicate that despite similar pre winter morphology but very contrasting energy levels the first winter season being 1 7 times more energetic than the second winter season the sediment budgets over the two winter periods were very similar as well as the cross shore dynamics of the extracted proxies associated with the dune foot and the berm the data collected suggest that this may be explained by the sequence of erosion recovery events driven by hydrodynamic conditions as the water level and energetic conditions and sediment transport thus during the first winter post storm recovery was effectively driven by energetic conditions while during the second winter inter storm conditions did not allow the initiation of recovery in between the storms apart from the control from wave conditions the seasonal beach response is also discussed within the framework of storm chronology and tidal range

beach dune interactions on the dry temperate danube delta coast abstract beach dune seasonal elevation changes aeolian sand transport measurements bathymetric surveys and shoreline evolution assessments were used to investigate annual and seasonal patterns of dune development on sf ntu gheorghe beach the danube delta coast from 1997 to 2004 dune volume increased consistently 1 96 m 3 m 1 y 1 to 5 1 m 3 m 1 y 1 over this 7 year period with higher rates in the southward downdrift direction dune aggradation is periodically limited by storms each of which marks a new evolutionary phase of the beach dune system as a consequence of the variable beach morphology and vegetation density during a year foredune growth occurs during the april december interval while between december and april a slightly erosive tendency is present the pattern of erosion and deposition shown by the topographical surveys is in good agreement with the sand transport measurements and demonstrates the presence of a vigorous sand flux over the foredunes which is 20 50 smaller than on the beach this high sand flux due to low precipitation and sparse vegetation cover creates an aerodynamically efficient morphology on the seaward dune slope the seaward dune face accretes during low to medium onshore winds 5 5 12 m s 1 and erodes during high winds 12 m s 1

transverse dune trailing ridges and vegetation succession abstract we describe the evolution of and vegetation succession on a previously undescribed landform transverse dune trailing ridges at el farallon transgressive dunefield in the state of veracruz mexico three dimensional clinometer compass and tape topographic surveys were conducted in conjunction with 1 m2 contiguous percent cover and presence absence vegetation survey transects at eight locations across two adjacent trailing ridges at the study site and elsewhere the transverse dune trailing ridges are formed by vegetation colonization of the lateral margins of active transverse barchanoidal transverse and akle or network dunes for simplicity all trailing ridges formed from these dune types are referred to as transverse dune trailing ridges because there are several transverse dunes in the dunefield multiple trailing ridges can be formed at one time two adjacent trailing ridges were examined the shortest length ridge was 70 m long and evolving from a 2 5 m high transverse dune while the longer ridge was 140 m long and evolving from an 8 m high dune trailing ridge length is a proxy measure of ridge age since the longer the ridge the greater the length of time since initial formation with increasing age or distance upwind species diversity increased as well as species horizontal extent and percent cover in turn the degree of bare sand decreased overall the data indicate a successional trend in the vegetation presence and cover with increasing age upwind those species most tolerant to burial croton and palafoxia begin the process of trailing ridge formation ipomoea and canavalia are less tolerant to burial and also are typically the next colonizing species trachypogon does not tolerate sand burial or deposition very well and only appears after significant stabilization has taken place the ridges display a moderately defined successional sequence in plant colonization and percentage cover with time and upwind distance they are significant geomorphologically as a unique landform in transgressive dunefields and also because they may be the only remaining indication of transverse dune presence and net dune migration direction once the dunefield is stabilized and in a final evolutionary state

lithofacies variations within sandur deposits the role of runoff regime flow dynamics and sediment supply characteristics abstract the icelandic sandur plains have for long acted as classic sites for models of braided river behaviour and of associated lithofacies assemblages however many of the icelandic sandurs are subject to repeated catastrophic flood events or jokulhlaups which are likely to have played a significant role in sandur construction established lithofacies models based on the icelandic sandurs have failed to take account of the varying runoff regimes which characterise the different sandur environments in addition sediment inputs to sandur channel systems are highly variable fluctuating in response both to varying runoff patterns and to advance and retreat of the source glacier that affect sediment availability within the proglacial zone this paper describes the main lithofacies types and vertical profiles that characterize the sandurs of south iceland and demonstrates that they can largely be attributed to extreme runoff events with few deposits typical of braided river facies occurring within the sedimentary record a preliminary qualitative model is developed that allows interpretation and prediction of vertical lithofacies profiles derived from glacial outwash in terms of i the drainage mechanism which in turn controls the dominant runoff population ii sediment availability and iii the spatial variability in flow dynamics

aeolian transport of sediment on a beach during and after rainfall wildwood nj usa abstract a field investigation was conducted 9 march 1994 on a dissipative beach to compare wind characteristics and aeolian transport during and after a light rain winds blew alongshore during the monitoring period moisture content of surface sediment on the backbeach was above 7 during rain and 4 four hours after rainfall ceased trapping rates measured using a cylindrical vertical trap were 14 1 kg m 1 h 1 during rainfall and 140 2 kg m 1 h 1 for a period beginning 3 h 33 min after rainfall ceased results indicate that light rain resulting in bulk surface moisture values over 7 is not sufficient to eliminate transport but the rate of transport is lower than can occur on the beach three to four hours following rain the amount of sand trapped at wildwood during rainfall is relatively high when compared to many previous studies on beaches in the absence of rain the great length of the beach as a source area combined with parallel or oblique winds are significant in increasing rates of sediment transport

morphology dynamics and internal stratification of some established foredunes in southeast australia abstract foredunes are shore parallel dunes formed by aeolian deposition within vegetation modern established foredunes are classified into five morphologic stages and the morphologies and processes of each is described stage 1 foredunes are well vegetated symmetric stable ridges characterised by stoss face and crest deposition stage 2 foredunes display minor erosional patches 75 90 vegetation cover and slight lateral variation in deposition and erosion stage 3 foredunes are hummocky have a 45 75 vegetation cover range and display various scales of blowouts concave stoss faces and steeper lee faces stage 4 foredunes are characterised by large scale erosional features such as blowouts sand sheets and high asymmetry stage 5 foredunes comprise poorly vegetated remnant knobs each stage is characterised by a set of erosional and depositional processes which produce generally distinctive sets of cross strata sedimentary structures within examples of each foredune stage are examined stage 1 and 2 foredunes are dominated by simple large scale convex continuous strata stage 3 and 4 foredunes display increasingly variable sets of cross strata and a greater degree of planar and trough cross stratification wave cut scarps blowout structures and very steep lee slope bedding may be preserved the internal sedimentary structures presented here form the basis of a facies model for foredunes

evaluation of a small volume renourishment strategy on a narrow mediterranean beach abstract a renourishment strategy for width maintenance of a mediterranean beach was evaluated using historical aerial photographs and topographic surveys the 5 5 km can picafort beach balearic islands spain consists of urbanised areas with associated anthropogenic pressures and a natural park extending for about 1 5 km where a backshore dune and a lagoon system have been preserved with the exception of this protected area the beach has been recurrently nourished over the past 20 years using relatively small volumes of sand

palaeoenvironmental reconstructions from linear dunefields recent progress current challenges and future directions abstract this paper reviews recent progress in the use of linear dunes as geoproxies of late quaternary environmental change summarises the challenges facing their use and explores some potential solutions to these challenges large areas of the swathes of linear dunes which occupy the continental interior of southern africa australia and parts of central asia and southern america currently have limited or negligible aeolian activity they have been recognised as offering potential information about past environments for more than a century but only with the widespread application of luminescence dating during the 1990s did they realistically start to offer the prospect of being an extensive dateable proxy of late quaternary palaeoenvironments and possibly palaeoclimates dating aeolian dune sands with luminescence methods is generally although not always relatively straightforward over the past twenty years a large number 1000 of luminescence ages have been added to the global dataset yet there has also been significant criticism of some of the rationale underpinning much of the interpretation of the records derived at the landscape scale developments of arguably equal importance have come from improved geomorphological understanding based on the wider availability of remotely sensed data and the paradigm of dunefield evolution as a self organising complex system current challenges are identified in three key regions incomplete understanding of how the process geomorphology of linear dunes affect the accumulation and preservation of sediment a lack of clarity regarding the temporal and spatial scale of the response in a dynamic environmental setting and uncertainty surrounding the drivers of changing rates of net accumulation solutions to these challenges lie within diverse research methodologies certainly further field study is required with improvement required in understanding system responses to changing environmental stimuli at scales from sedimentological to landscape in parallel the full implications of complex systems approaches to aeolian geomorphology for linear dunes lag behind the adoption of the concept to some other dune forms e g barchans the relationship between observed dune complexity and age from field data complicates previous suggestions that dune patterning may be purely a function of development time parallel to this lies the need to improve interpretation of the results of dune geochronological studies a suggestion is offered which aims to test the statistical significance of dune accumulation time series by comparison with a modelled system with unchanging external forcing despite the initial promise of linear dune records as a revolutionary source of palaeoenvironmental information in drylands the outcomes to date have been coarse although still valuable in resolution perhaps the most valuable realization has been that geomorphological understanding of these widespread landforms is incomplete

multiple origins of linear dunes on earth and titan the formation of dunes is controlled by the direction of the prevailing winds and the characteristics of the sediments linear dunes in the qaidam basin china are shown to form from cohesive sediments a model that could be applicable to dunes on titan

morphodynamic variability of high energy macrotidal beaches cornwall uk abstract spatial data collected over three years are presented to assess the extent of morphological variability under seasonal and storm waves on two high energy macrotidal beaches on the north cornish coast of particular interest was the degree to which the beaches displayed bar rip morphology and a novel approach to quantify the three dimensionality of the beach based on the curvature of the bottom contours is adopted to identify and classify the three dimensional beach response to changes in the dominant forcing conditions morphologically the beaches range from dissipative to intermediate and are characterised by low tide bar rip morphology which plays a key role in the nearshore dynamics and beach safety real time kinematic rtk gps surveys were undertaken using an all terrain vehicle to measure the three dimensional 3d morphology in addition nearshore wave data in situ hydrodynamic measurements local tide gauges and argus video data allowed detailed analysis of process response mechanisms for long term yearly seasonal monthly storm weekly daily and tidal hourly morphological behaviour both sites exhibited net long term accretion derived from the intertidal beach volume throughout the survey period inter site similarity in beach response was observed in response to storm waves yet coupling between the seasonal wave climate and the beach morphology was not evident at either of the sites increased wave conditions exceeding hs 4 m during sustained storm events 50 h led to offshore transport from the beachface to the subtidal bar region post storm recovery was characterised by onshore transport and the development of substantial 3d low tide morphology under normal wave conditions hs 1 6 m the dominant 3d features smoothed out as channels in filled and bar prominence reduced over a period of 2 3 months overall the beaches exhibited a significant storm dominated morphological response cycle unlike the more familiar winter summer seasonal response

beach dune morphological relationships and erosion accretion an investigation at five sites in england and wales using lidar data abstract the critical relationships between beach and nearshore parameters and the erosion accretion status of frontal dunes have been investigated using lidar data complemented by data obtained from conventional topographic and bathymetric surveys at five dune systems in england and wales morphometric parameters calculated from the lidar data demonstrate the presence of a general relationship between beach morphology dune morphology and erosion accretion eroding dunes were found to be associated with narrower steeper beaches whilst accreting dunes were associated with wider low angle beaches however the critical beach width mean slope angle separating eroding dunes from stable or accreting dunes was found to vary between sites at any given site changes in beach width slope over time can be used to provide an early warning of changes in frontal dune erosion accretion behaviour

rupture history of the january 1 1996 ms 6 6 volcanic earthquake preceding the simultaneous eruption of karymsky and akademia nauk volcanoes in kamchatka russia the intensive foreshock mainshock aftershock sequence of earthquakes preceded and accompanied the january 2 1996 simultaneous eruption of the active karymsky and the dormant akademia nauk volcanoes in kamchatka russia the finite fault broad band teleseismic p waveform inversion was applied to the ms 6 6 mainshock of this sequence which occurred on january 1 1996 about 14 hours before the beginning of eruption it was one of the strongest volcano tectonic earthquakes in this century after the 1912 1914 great ms 7 0 volcanic earthquakes related to the katmai alaska and sakurajima japan volcanic eruptions the main feature of the rupture process inferred from the inversion was the breaking of a sequence of four asperities with displacement greater than 200 cm which were situated at depths from 0 to 35 km just beneath the akademia nauk volcano there were no broken asperities beneath the karymsky volcano the majority of small earthquake foci were located out of maximum asperities and filled a space between two zones of asperities at depths from 12 to 20 km the position of broken asperities allows us to suggest that during the large earthquake rupturing an ancient magmatic column beneath the volcano was destroyed small earthquakes which were recorded mainly from 5 to 20 km depth were able only to destroy the intermediate depth part of this column between 12 and 20 km the main work for opening a way to move magma to the surface was made by a large shock which had broken the upper and deep parts of the ancient magma column

wind blown sand on beaches an evaluation of models five models for predicting rates of aeolian sand transport were evaluated using empirical data obtained from field experiments conducted in april 1994 at a beach on inch spit co kerry republic of ireland measurements were made of vertical wind profiles to derive shear velocity estimates beach slope and rates of sand transport sediment samples were taken to assess characteristics of grain size and surface moisture content estimates of threshold shear velocity were derived using grain size data after parsing the field data on the basis of the quality of shear velocity estimation and the occurrence of blowing sand 51 data sets describing rates of sand transport and environmental conditions were retained mean grain diameter was 0 17 mm surface slopes ranged from 0 02 on the foreshore to about 0 11 near the dune toe mean shear velocities ranged from 0 23 m s 1 just above the observed transport threshold to 0 65 m s 1 rates of transport ranged from 0 02 kg m 1 h 1 to more than 80 kg m 1 h 1 these data were used as input to the models of bagnold bagnold r a 1936 the movement of desert sand proc r soc london a157 594 620 kawamura kawamura r 1951 study of sand movement by wind translated 1965 as university of california hydraulics engineering laboratory report hel 2 8 berkeley zingg zingg a w 1953 wind tunnel studies of the movement of sedimentary material proc 5th hydraulics conf bull 34 iowa city inst of hydraulics pp 111 135 kadib kadib a a 1965 a function for sand movement by wind university of california hydraulics engineering laboratory report hel 2 8 berkeley and lettau and lettau lettau k and lettau h 1977 experimental and micrometeorological field studies of dune migration in k lettau and h lettau eds exploring the world s driest climate university of wisconsin madison ies report 101 pp 110 147 correction factors to adjust predictions of the rate of transport to account for the effects of slope and moisture content were calculated using the models of bagnold bagnold r a 1973 the nature of saltation and bed load transport in water proc r soc london ser a 332 473 504 and belly belly p y 1964 sand movement by wind u s army corps eng cerc tech mem 1 washington d c 38 pp respectively none of the models was able to produce a strong correspondence between measured and predicted rates of transport best results were obtained using the bagnold and zingg models and the kadib model was the least viable of this group the influence of sediment moisture content appeared to be the critical factor in degrading model viability overall none of the models is adequate for general applications to coastal aeolian environments where moisture content complications tend to override the predictive competence of the simple transport formulations c 1998 elsevier science b v