sea cliffs their processes profiles and classification general concavity or convexity of sea cliff profiles is controlled by relative rates of erosion by marine and subaerial processes as well as by positions of more resistant strata in the cliffs profiles supplemented by on site examination can establish the activity and dominance of erosional processes and indicate changes in regimen a sharp angle at the sea cliff base generally indicates active marine erosion whereas a smooth curve at the base means that subaerial erosion may dominate talus shows absence of marine erosion studies of profiles can be useful for estimating stability for residences railroads and highways at the top face and base of sea cliffs generally increased erosion and retreat of sea cliffs are in prospect because of projected regionally wetter and stormier climate rising sea level and increased human activities

microseismic measurement of wave energy delivery to a rocky coast rocky coasts are attacked by waves that drive sea cliff retreat and etch promontories and embayments into the coastline understanding the evolution of such coastlines requires knowledge of the energy supplied by waves which should depend upon both the deep water waves and the coastal bathymetry they cross we employ microseismic measurements of the wave induced shaking of sea cliffs near santa cruz california as a proxy for the temporal pattern of wave energy delivery to the coast during much of the winter 2001 storm season visual inspection of the time series suggests that both deep water wave heights and tide levels exert considerable control on the energy delivered we test this concept quantitatively with two models in which synthetic time series of wave power at the coast are compared with the shaking data in the first model deep water wave power is linearly scaled by a fitting parameter because this model fails to account for the strong tidal signal it fits poorly in the second model the wave transformation associated with shoaling and refraction diminishes the nearshore wave power and dissipation associated with bottom drag and wave breaking is parameterized by exponential dependencies on two length scales this model reduces the variance by 32 45 and captures the essence of the full signal shoaling and refraction greatly modulate the wave power delivered to the coast energy dissipated by bottom drag across the shelf is relatively small the dissipation length scale is many times the path length across the shelf in contrast much energy is dissipated in the surf zone the tidal dissipation depth scale is of the same order as the tidal range 1 2 m which accounts for the strong dependence of the cliff shaking on the tide

the temporal and spatial scales of rocky coast geomorphology a commentary rocky shores are complex landforms that result from marine erosion and subaerial weathering they are time integrated features where their present day form is the result of instantaneous erosion often on the millimetre to sub metre scale occurring for centuries to millennia as a result research on rocky coasts focuses on a range of temporal and spatial scales from granular scale swelling of a rock surface and instantaneous wave impact to modelling millennial scale sea level drivers the challenge for rocky coast researchers is either to upscale or to downscale their results to the human timescales of greatest interest to managers the research presented in earth surface processes and landforms over the past 3 years highlights the range of spatial and temporal approaches to the study of coastal cliffs and shore platforms we identify a key temporal and spatial gap in current research seasonal annual timeframes over hundreds of metres to kilometre scale studies appear to be lacking and are likely critical in understanding the future evolution of rocky coasts especially their response to climate change copyright 2017 john wiley sons ltd

morphostructural evolution and related kinematics of rockfalls in campania southern italy a case study abstract on the southern slope of the sorrentine peninsula there are many subtriangular depressions in which the main townsof the area are located the depressions are linked to block rotation during strike slip fault activity and are oftenmarked by high subvertical cliffs and related rockfall phenomena with consequent damage to the underlying towns on the basis of back analyses carried out using hoek s method an in depthstudy of some of the rockfalls enabled us todefine for one of these towns the most suitable shock restitution coefficients of the detritical pyroclastic deposits present on the terraces situated at the foot of the cliffs on the basis of the main kinematic parameters of actual rockfalls and approximately 6600 simulated rockfalls a planning of the high level rockfall risk valley bottoms was drawn up the size of the high level rockfall risk sites depends above all on the presence number and size of the terracings wherecitrus fruit trees are cultivated the calculation method suggested by paronuzzi was also adopted in order to make a detailed evaluation of the role the terraces play in modifying the trajectory height the translation velocity and the endpoint of the boulders although there are methodological and statistical differences between the two methods results from both studies showed sufficient correlation in particular concerning the trajectories endpoints

djerfisherite in kimberlites and their xenoliths implications for kimberlite melt evolution djerfisherite k6 fe ni cu 25s26cl occurs as an accessory phase in the groundmass of many kimberlites kimberlite hosted mantle xenoliths and as a daughter inclusion phase in diamonds and kimberlitic minerals djerfisherite typically occurs as replacement of pre existing fe ni cu sulphides i e pyrrhotite pentlandite and chalcopyrite but can also occur as individual grains or as poikilitic phase in the groundmass of kimberlites in this study we present new constraints on the origin and genesis of djerfisherite in kimberlites and their entrained xenoliths djerfisherite has extremely heterogeneous compositions in terms of fe ni and cu ratios however there appears to be no distinct compositional range of djerfisherite indicative of a particular setting i e kimberlites xenoliths or diamonds rather this compositional diversity reflects the composition of the host kimberlite melt and or interacting metasomatic medium in addition djerfisherite may contain k and cl contents less than the ideal formula unit raman spectroscopy and electron backscatter diffraction ebsd revealed that these k cl poor sulphides still maintain the same djerfisherite crystal structure two potential mechanisms for djerfisherite formation are considered 1 replacement of pre existing fe ni cu sulphides by djerfisherite which is attributed to precursor sulphides reacting with metasomatic k cl bearing melts fluids in the mantle or the transporting kimberlite melt 2 direct crystallisation of djerfisherite from the kimberlite melt in groundmass or due to kimberlite melt infiltration into xenoliths the occurrence of djerfisherite in kimberlites and its mantle cargo from localities worldwide provides strong evidence that the metasomatising infiltrating kimberlite melt fluid was enriched in k and cl we suggest that kimberlites originated from melts that were more enriched in alkalis and halogens relative to their whole rock compositions

coastal cliff behaviour observations on the relationship between beach levels and recession rates abstract beaches dissipate wave energy and regulate the frequency that the cliff foot is subject to wave attack the relationship between beach levels and cliff recession rates has been established for pleistocene soft rock cliffs along the north norfolk and suffolk coasts uk the results suggest that over a decadal timescale there is a non linear increase in the average recession rate as the beach profile area above high water mark hwm decreases small changes in beach level can result in significant differences in the recession rates the impact of a unit change in beach level on the recession rate depends on the initial beach level on a year by year basis it is possible to divide the beach level and recession relationship into a series of zones with characteristic types of behaviour at low beach levels there is high to extremely high recession with considerable variability whereas at high beach levels there is almost zero recession with limited variability it is concluded that historical recession rates are the product of both the past forcing events and changes in cliff beach state extrapolation of historical rates can be extremely unreliable unless it is supported by an understanding of the dynamic behaviour of the cliff beach system and the energy inputs over the observation period

marine and subaerial controls of coastal chalk cliff erosion in normandy france based on a 7 year laser scanner monitoring abstract between october 2010 and november 2017 surveys using terrestrial laser scanning tls were carried out every 4 5 months to monitor erosion on three chalk cliff faces with close structural characteristics in normandy the two dieppe sites are abandoned cliffs while the varengeville sur mer site is an active one the uniqueness of this paper is the comparison between these cliff sections and the significance of marine and or subaerial controls in erosion beyond the quantification of annual retreat rates which on the active cliff are currently 36 times greater than on the abandoned cliffs this paper highlights the fundamental efficacy of marine controls in the current cliff erosion and the removal of falls analyses of modalities of retreat and profile evolution according to a naturalistic approach subaerial processes appear to have a less erosive action than marine ones because the studied abandoned cliffs show low erosion dynamics and have maintained a subvertical profile despite continentalization for between 30 to more than 120 years

constraints on kimberlite ascent mechanisms revealed by phlogopite compositions in kimberlites and mantle xenoliths abstract kimberlite magmas are of economic and scientific importance because they represent the major host to diamonds and are probably the deepest magmas from continental regions in addition kimberlite magmas transport abundant mantle and crustal xenoliths thus providing fundamental information on the composition of the sub continental lithosphere despite their importance the composition and ascent mechanism s of kimberlite melts remain poorly constrained phlogopite is one of the few minerals that preserves a history of fluid migration and magmatism in the mantle and crust and is therefore an invaluable petrogenetic indicator of kimberlite magma evolution here we present major and trace element compositional data for phlogopite from the bultfontein kimberlite kimberley south africa i e the kimberlite type locality and from entrained mantle xenoliths phlogopite macrocrysts 0 3 0 5 mm and microcrysts between 0 1 and 0 3 mm in the bultfontein kimberlite display concentric compositional zoning patterns the cores of these phlogopite grains exhibit compositions typical of phlogopite contained in peridotite mantle xenoliths however the rims of some grains show compositions analogous to kimberlite groundmass phlogopite i e high ti al and ba low cr whereas other rims and intermediate zones between cores and rims exhibit unusually elevated cr and lower al and ba concentrations the latter compositions are indistinguishable from matrix phlogopite in polymict breccia xenoliths considered to represent failed kimberlite intrusions and from ti rich overgrowth rims on phlogopite in other mantle xenoliths consequently it is likely that these phlogopite grains crystallized from kimberlite melts and that the high ti cr zones originated from earlier kimberlite melts at mantle depths we postulate that successive pulses of ascending kimberlite magma progressively metasomatised the conduit along which later kimberlite pulses ascended producing progressively decreasing interaction with the surrounding mantle rocks in our view these processes represent the fundamental mechanism of kimberlite magma ascent our study also indicates that in addition to xenoliths xenocrysts and magmatic phases kimberlite rocks incorporate material crystallized at various mantle depths by previous kimberlite intrusions mantle derived antecrysts

fractal dimension of the hydrographic pattern of three large rivers in the mediterranean morphoclimatic system geomorphologic interpretation of russian usa ebro spain and volturno italy fluvial geometry by applying fractal geometry analysis to the drainage network of three large watercourses in america and europe we have calculated for the first time their fractal dimension the aim is to interpret the geomorphologic characteristics to better understand the morphoevolutionary processes of these fluvial morphotypes to identify and discriminate geomorphic phenomena responsible for any difference or convergence of a fractal dimension to classify hydrographic patterns and finally to compare the fractal degree with some geomorphic quantitative indexes the analyzed catchment of russian california usa ebro spain and volturno italy rivers are situated in mediterranean climate regions sensu koppen but with different geologic context and tectonic styles results show fractal dimensions ranging from 1 08 to 1 50 according to the geological setting and geomorphic indexes of these basins the lower fractal degree indicates a prevailing tectonics active or not while the higher degree indicates the stronger erosion processes on inherited landscapes

human influence and the changing geomorphology of mediterranean deltas and coasts over the last 6000 years from progradation to destruction phase the present geomorphology of the mediterranean s coasts is largely a product of an intricate long term relationship between nature and human societies a cradle of ancient civilisations the mediterranean has seen its shores occupied by humans since prehistory and is therefore a particularly pertinent unit of analysis the morphotectonic context and other forcing agents e g climate shaped out a highly diversified coastal morphology and generated a sediment supply regime potentially favourable to the formation of numerous open coast deltas and bay head deltas in infilled rias as sea level stabilised during the mid holocene this supply of riverine sediment has also been the key agent in mediating human occupation of the mediterranean s clastic coasts expressions of this relationship have been extensively archived in clastic coastal deposits including base level deltaic and estuarine sedimentary sinks which comprise records to explore the interactions between geosystems and the human environment the stratigraphic sequences in these coastal sedimentary archives comprise in many places a clearly identified anthropogenic signature notably in ancient harbours some of which underwent extremely rapid silting up due to massive sediment sourcing generated by new agricultural practices from the neolithic onwards increasing human influence especially over the last 3000 years has been in turn an important driver of changes in sediment supply strongly modulating deltaic development pulses of sediment supply from catchments rendered vulnerable by human perturbations during the roman period resulted in a new cycle of inception of many other deltas and in rapid delta growth e g the ebro the po the arno and the ombrone another progradation dynamic during the little ice age at a time of strong rural population growth river discharge increases technological developments and urbanisation further consolidated delta growth understanding the life cycle of these deltas since their initial formation is in turn key to unravelling the relative role of natural and anthropogenic forcing agents rapid climate changes are deemed to have contributed through both the stripping of landscapes rendered fragile by human activities and active fluvial sediment transport to the coast but disentangling climate change effects from human impacts in the mediterranean remains a challenge the patterns of subsequent deltaic growth and delta morphodynamics reflect adaptations to pulsed sediment supply river discharge variations the microtidal fetch limited context of the mediterranean and direct engineering interventions the progradation dynamic of the roman period and little ice age contrasts markedly with the situation of common coastal destabilisation over the last two centuries particularly well documented for the last 50 years this period has been characterised by reduced sediment flux to base level geosystems due to catchment reforestation retenion within reservoirs fluvial regulation and dredging resulting in the erosion of deltas and barrier lagoon and beach dune systems large stretches of shoreline and narrow coastal plains have been massively engineered for coastal defence and protection against erosion but also for the construction of marinas leisure harbours and artificial beaches resulting in the emergence of veritable artificial seafronts these interventions have collectively and progressively raised societies to a pervasive and overarching position in the geomorphic stability instability of the mediterranean s coasts a situation that will be exacerbated by pressures from sea level rise paving the way for rampant coastal erosion and delta destruction

crystalline inclusions and c isotope ratios in diamonds from the snap lake king lake kimberlite dyke system evidence of ultradeep and enriched lithospheric mantle abstract u type paragenesis inclusions predominate 94 7 among the crystalline inclusion suite of 115 diamonds 4 2 mm obtained from the recently discovered snap lake king lake skl kimberlite dyke system southern slave canada the most common inclusions are olivine 90 and enstatite 22 sulfide cr pyrope chromite and cr diopside inclusion are less abundant 15 10 5 and 1 respectively results of the inclusion composition study demonstrate the following a the relatively enriched character of the mantle parent rocks of the u type diamonds the average mg of olivine inclusions is 92 1 and of enstatite inclusions average 93 3 cao content in cr pyrope inclusions is relatively high 3 73 5 75 wt b four of ten u type cr rich pyrope inclusions contain a majoritic component up to 16 8 mol which requires pressures of 110 kbar carbon isotopes compositions for 34 diamonds with u type inclusions have a 13c range from 3 2 to 9 with a strong peak around 3 5 this is much heavier than the ratios of u type diamonds from siberia and south africa 4 5 diamonds with olivine inclusions can be divided into two groups based on their 13c values as well as the mg and ni fe ratio in the olivines most show a narrow range of 13c values from 3 2 to 4 8 average 3 72 and have olivine inclusions with mg less than 92 3 and relatively high fe ni ratios a second group is characterized by a much wider variation of c isotope composition 13c varies from 3 8 to 9 0 average 5 97 and the olivine inclusions having a higher mg up to 93 6 and relatively low fe ni ratios this difference in the c isotope composition may have several explanations a peculiarities of asthenosphere degassing coupled with an abnormal thickness of lithosphere b the abnormal thickness and enriched character of lithospheric mantle c involvement of subducted c of crustal origin in the processes of the diamond formation the presence of subcalcic cr rich majorite up to 17 mol pyropes of low ca harzburgite paragenesis among the crystalline inclusion suite of skl diamonds is strong evidence for the existence of diamondiferous depleted peridotite in lithospheric mantle at depth near 300 km beneath southern slave area and is postulated to be one of the main reasons for the much heavier c isotope composition of skl u type diamonds in comparison with those from siberian and south african kimberlites

geomorphological features of the archaeological marine area of sinuessa in campania southern italy abstract submarine surveys carried out since the 90s along the coastland of sinuessa allowed us to draw up a geomorphological map with archaeological findings along the sea bottom 650 m off and 7 m depth a campanian ignimbrite bedrock was detected dated 39 kyr bp its position is incompatible with the current sea level towards the northern edge of the shoal a depressed area with 24 cubic elements in concrete was surveyed these artefacts pilae are typical of roman maritime structures widespread along the southernmost phlegrean coast beachrocks and accessory landforms at the same depth of bedrock suggest that this was emerging and attended by man in roman times even for activities related to port facilities submerged palaeo channels in alignment of current watercourses on the mainland dissect the shoal these channels were moulded in subaerial environment during wurm glaciation following the tuff deposition and then were drowned by sea level rise the northernmost channel next to the pilae likely allowed transit and manoeuvring of roman ships the discovery along the seabed of a large stump of lead anchor hundreds of roman amphorae and fragments as well as of a depression of millstone confirm this finding probably the sinuous physiography favored the choice of this site for the docking of sinuessa as sheltered from storms

geomorphology of soft clastic rock coasts in the mid western adriatic sea abruzzo italy abstract we present the first detailed overall study on the rock coasts in the central adriatic sea abruzzo italy which is one of the few cases of a coast with clastic soft rocks in the entire mediterranean area the coast is composed of cliffs with small beaches coastal slopes with or without a contiguous coastal plain and intervening low lying coasts it is developed on the eastern seaward side of a wide plateau and mesa landscape shaped on an early middle pleistocene clay sand sandstone conglomerate marine sequence covered by late pleistocene holocene continental deposits the study focuses on the overall coast and on eight specific sites combining i dem 2 m cell lidar derived analysis and geological geomorphological surveys of the emerged and submerged areas for the cliff coastal slope characterization ii the results of u th 14c sediment dating and archaeological and palaeontological attributions for constraining the coastal evolution and iii aerial photo time series 1954 2013 time span analysis for the recent cliff retreat assessment the overall features of the cliffs and coastal slopes were defined in terms of their morphology lithology tectonic setting landforms and geomorphological processes whereas the analysis of late pleistocene holocene continental deposits and landform distribution defined and constrained the evolution of the coastal system this enabled us to define eight different types of coastal cliffs slopes meaningful for clastic soft rock coasts the coastal types were defined in terms of i lithology 15 cliffs on marine sandstone 15 cliffs on marine conglomerate 3 cliffs on continental deposits 43 coastal slopes on clay sand sandstone conglomerate sequences ii morphostructural setting i e clay sandstone conglomerate interface elevation and iii of state of activity 3 8 active cliffs 13 8 inactive cliffs 15 9 palaeocliffs 43 of inactive and locally reactivated landslides on coastal slopes variable retreat rates were also defined from retreat measurements over a 60 year time span ranging from 0 15 m yr to 1 m yr and were found to be induced by episodic and localized cliff recession processes and connected to combined wave cut and gravity induced slope processes the assessment of coastal and gravity induced geomorphological processes combined with the analysis and dating of the continental deposits allowed us to define the late pleistocene to present evolution and timing and the evolutionary mechanisms of the main coastal types of soft rock coasts they are connected to wave cut and gravity induced erosion cycles on cliffs and to large rotational ancient landsliding with local recent reactivations on coastal slopes for the different coastal types the expected hazard conditions were outlined

a predictive model for wave induced cliff erosion with application to pacific coasts of japan a model for predicting the rate of short term bluff recession originally derived from wave tank experiments is tested under field conditions the fundamental equation is dx dt k c ln gh sc where dx dt is the recession rate h is the wave height at the cliff base sc is the compressive strength of the cliff forming material is the density of water g is the acceleration due to gravity c is a nondimensional constant and k is a constant with units of lt 1 the critical wave height to initiate erosion hcrit is given by hcrit sce c g this model is applied to two eroding tertiary cliffs in japan both facing the pacific ocean results show that 1 the larger but rarer waves only cause cliff erosion compared with the smaller but more common waves and 2 the erosion rate at each site is greatly affected by the occurrence frequency of waves higher than hcrit

a new process response coastal recession model of soft rock cliffs abstract the development of cliff erosion predictive models is limited by the complex interactions between environmental processes and material properties over a range of temporal and spatial scales current models incorporate a stochastic representation of cliff behavior based on assumptions regarding the magnitude and frequency of events in a probabilistic framework the new model presented here has been developed to incorporate the behavioral and mechanical characteristics of coastal cliffs which are dominated geologically by overconsolidated clays tills and an associated protective colluvial wedge this model is capable of providing precise and stable responses to some of the inherent uncertainties in cliff recession processes including those caused by different failure mechanisms e g colluvium generation groundwater and erosive tidal cycles material strength is incorporated using the unconfined compressive strength of the material that composes the cliff unlike previous models a calibration parameter is restricted to account for uncertainties linked to marine processes the mechanisms of cliffline retreat have been identified as slump and topple landslides once cliff material has fallen colluvium formation at the cliff foot is incorporated into the model using three different procedures according to the geomechanical characteristics of the debris the model is validated through profile evolution assessment at various locations of coastline retreat on the holderness coast uk higher groundwater content also produces an increase in the number and size of the slope failures the results represent an important step forward in linking material properties to the processes of cliff recession

polymict breccia xenoliths evidence for the complex character of kimberlite formation abstract very rare xenoliths of polymict breccia provide important information for understanding the nature mechanism and conditions of kimberlite forming processes the purposes of this study are a to detail the petrology and mineralogy of the first find of a polymict breccia xenolith from the precambrian premier mine south africa and the same type of xenolith from the middle paleozoic sytykanskaya pipe yakutia and b to estimate the possible relationship between the polymict breccias and kimberlite formation a comparative analysis of extreme disequilibrium between the mineral phases leads to the conclusion that upper mantle material from a depth interval from 120 to 220 km is present in the studied xenoliths a combination of compositional and petrographic features shows that initially the most deep seated material from the base of the lithospheric mantle was intensely deformed under conditions of significant deviatoric stress and then the first stage of partial melting produced a liquid fraction which served as a lubricant that enabled movement of the mixture of dominantly solid phases plus minor liquid from the base of the lithosphere to a shallower level in the lithospheric mantle the absence of material of crustal origin or from the upper levels of lithospheric mantle in the studied polymict breccias leads to the conclusion that before the transportation to the earth surface this complex mixture halted for a very short time but enough for its consolidation at a depth near 120 km so most probably the formation of polymict breccias was directly related to the initial phases of kimberlite formation and polymict breccias are a type of underdeveloped embryo of ordinary kimberlite

retreat rates modalities and agents responsible for erosion along the coastal chalk cliffs of upper normandy the contribution of terrestrial laser scanning in order to follow all the changes affecting the coastal chalk cliff face in upper normandy and improve knowledge about cliff erosion repeated terrestrial laser scanning tls surveys were carried out frequently between 2010 and 2013 every 4 5 months they were conducted at two sites with similar lithostratigraphic characteristics but different exposures to marine actions the former being an abandoned cliff and the latter an active cliff they provide a quantification of the production of debris with centimeter precision from 0 01 to 0 04 m these surveys provided three major outcomes 1 cliff retreat rates were measured at high spatial resolution with retreat values unsurprisingly 3 4 times higher for an active cliff than for an abandoned cliff this result highlights that marine actions should be seen as not only a transport agent but also a particularly effective erosion agent 2 a significant proportion of debris fall production about 25 in the total active cliff retreat was identified and 3 one of the modalities of retreat was visualized as the creation of a basal notch which propagates instability towards the upper part of the cliff face later this instability generates rock falls coming from the whole cliff face

experimental frost and salt weathering of chalk i experiments are described in which chalk cubes were soaked in solutions of either sodium chloride sodium sulphate or magnesium sulphate at concentrations of 5 5 per cent and 12 5 per cent or in a mixed solution of sodium chloride and sodium sulphate or in distilled water after removal of excess liquid the cubes were subjected to six freeze thaw cycles with temperatures ranging from either 15 to 10 c or 15 to 30 c the results confirm that frost weathering can be enhanced by the presence of certain salts but the extent of weathering was much less than that previously reported for samples frozen totally immersed in the same liquids evidence is presented which suggests that salt crystallization is the major weathering process operative when non immersed samples are frozen but a combination of frost and salt weathering operates when fully immersed samples are frozen

a pattern in the incidence of major coastal mudslides the communication considers eroding coastal cliffs which consist predominantly of stiff fissured clay overlying a more resistant stratum the contact having a gentle component of coastwise dip from the southern coasts of england five such cliffs are described in each of these a zone of dominant mudsliding exists which stands out from the background of lesser mudslides and other forms of failure the common feature is that in each case the zone of major mudsliding coincides closely with the length of cliff over which the base of the clay stratum lies within the tidal range and generally within the upper part of this it is suggested that this pattern results from optimum conditions for continuing stimulation of mudslide activity by toe erosion being reached in the above zone

erosion risk assessment of active coastal cliffs in temperate environments the potentially negative consequences resulting from cliff recession are a matter of serious concern in many coastal areas worldwide the assessment of such processes has traditionally been performed by calculating average cliff recession rates and projecting them into the future without taking into consideration the diverse factors affecting cliff dynamics and stability in this work a new practical method is presented to evaluate cliff erosion risk in temperate environments by analysing the main factors responsible for both the physical and the socioeconomic aspects of erosion representing cliff loss potential and damage potential respectively for this purpose an integration of 11 physical variables such as cliff lithology beach characteristics or rainfall regime and 6 socioeconomic variables such as land use type or population density is proposed these variables are weighted and combined into a hazard index and an impact index which in turn are merged into a composite risk index where the resulting values are normalized and expressed as a percentage of the maximum theoretical risk the method is tested and validated by using data about cliff retreat rates and mass movement processes in the coast of cadiz province sw spain the proposed approach allows the zoning of coastal cliffs according to the risk hazard and or impact levels including the recognition of critical areas where specific intervention strategies should be adopted the method presented in this work is deemed both practical and scientifically valid without requiring extensive and detailed surveys of the area where it is to be applied this way it constitutes an easy to use valuable tool for decision making regarding land use planning and management strategies for active coastal cliffs

rainfall induced debris flows in pyroclastic deposits campania southern italy abstract a combination of empirical and physically based hydrological models has been used to analyze historical data on rainfall and debris flow occurrence in western campania to examine the correlation between rainfall and debris flow events rainfall data from major storms recorded in recent decades in western campania were compiled including daily series from several rain gauges located inside landslide areas supplemented by hourly rainfall data from some of the principal storms a two phase approach is proposed during phase 1 soil moisture levels have been modelled as the hydrological balance between precipitation and evapotranspiration on a daily scale using the method of thornthwaite geograph rev 38 1948 55 phase 2 is related to the accumulation of surplus moisture from intense rainfall leading to the development of positive pore pressures these interactions take place on an hourly time scale by the leaky barrel lb model described by wilson and wiezoreck env eng geoscience 1 1995 11 in combination with hourly rainfall records the lb model has been used to compare hydrological effects of different storms the critical level of retained rain water has been fixed by the timing of debris flow activity related to recorded storm events new rainfall intensity duration thresholds for debris flow initiation in western campania are proposed these thresholds are related to individual rain gauge and assume a previously satisfied field capacity condition the new thresholds are somewhat higher than those plotted by previous authors but are thought to be more accurate and thus need less conservatism

coastal hazard assessment and mapping in northern campania italy abstract in the northern campanian coastal zone over 150 km long three geomorphic units are recognised 1 sandy beaches that are well developed in the northern area where a prominent river mouth volturno river is also present 2 steep and rocky shores often with gravelly beaches or debris cones at their base are mainly diffuse in the southern area sorrentine peninsula and lastly 3 techno coast shorelines stabilized with revetments and seawalls as well as former natural environments no longer clearly operational because of urbanization as is visible in naples and in the vesuvian coast six primary hazards are considered in this investigation shoreline erosion riverine flooding storms landslides seismicity and volcanism and man made structures these hazards do not have a uniform distribution along this coast in terms of their frequency and intensity moreover both their interaction and the intensive action of humans often uncontrolled makes it difficult to assess the overall coastal hazard in this paper a semi quantitative method with which to quantify rank and map the distribution of hazard is applied along this particular stretch of coast in such a stretch previously characterized in terms of types and processes and compartmentalized into geomorphic units the effect of individual hazards based on their magnitude and recurrence is evaluated dominant and subordinate hazards for each geomorphic unit are identified assigning a rank that is also a weighting comparison of each weighting through an interaction matrix permits the calculation of a resultant which is the overall hazard assessment and which can be expressed cartographically the results obtained for a coastal zone with one of the highest pressures from urbanization in the world help us to recognise that this approach could become a useful tool to aid decision making regarding coastal land use and planning

effect of groundwater and sea weathering cycles on the strength of chalk rock from unstable coastal cliffs of nw france abstract the aim of this paper is to evaluate the role of groundwater and sea weathering on the strength of the chalk rocks exposed on the coastline of the english channel in normandy nw france we present a study of the rock strength variations of three representative chalk units lewes chalk seaford chalk and newhaven chalk exposed at various locations on the coastal chalk cliffs the combination of ucs tests and sem observations have been used 1 on dry natural chalk samples 2 on chalk samples at various moisture contents 3 on dry chalk samples submitted to a 10 day cycle of alternating wetting and drying by distilled water and by sea water dry chalk samples show low ucs strength 3 46 4 mpa indicative of very weak rocks when chalk samples are submitted to progressive water wetting they present a decrease of ucs strength and young s modulus of 40 to 50 this behaviour begins at low values of water content within the chalk i e for a degree of water saturation ranging between 10 and 17 when chalk samples are submitted to an artificial weathering cycle with distilled water a decrease in strength is observed whereas the young s modulus increases sem observations indicate the occurrence of microcracks and particle aggregates in the sample when chalk samples are submitted to an artificial weathering with sea water the decrease of ucs strength and young s modulus achieves a minimum sem observations indicate salt crystals within the chalk on the coastal cliffs of nw france weathering processes depend both on chalk lithology which show a range of sensitivity to weathering and on the location of the chalk in the coastal area processes allied to the degree of weathering e g salt crystallisation or fresh water disaggregation differ in the chalk massif on the cliff face and on the shore platform

the role of thermal stress fatigue in the breakdown of rock in cold regions abstract many geomorphological studies have ignored the role of thermal stress fatigue engineers have long maintained that thermal stress is an effective process physicists and the ceramics industry have provided a theoretical foundation to explain the nature and mode of operation of thermal breakdown recent geomorphological studies have shown the importance of thermal stress in cold regions by means of high frequency rock temperature data which can identify rates of temperature change in excess of 2 c min 1 the occurrence of weathered material in cold but dry regions can be explained by thermal stress shock differential radiation receipts on slopes of varying orientation and gradient can exert a very strong effect

cross shore decay of cliff top ground motions driven by local ocean swell and infragravity waves 1 ground motions at the frequencies between 0 01 and 0 1 hz of ocean infragravity and swell waves were observed on a cross shore transect extending landward from the edge of a southern california coastal cliff cliff top ground motions are coherent and in phase with water level fluctuations at the cliff base vertical ground motions at infragravity and single frequencies decay rapidly with inland distance from the cliff edge e folding scale is about 12 m and at the edge decrease by several orders of magnitude between high tide when waves reach the cliff base and low tide when the waterline is about 50 m from the cliff base the observed cross shore decay scales are qualitatively consistent with gravitational loading and attraction of water waves at tidally modulated distances from the cliff base at approximately constant distance from the waterline ground motions vary roughly linearly with nearshore swell wave energy in contrast to these locally forced ground motions double frequency band 0 1 0 2 hz cliff top vertical ground motions are remotely generated with spatially uniform magnitudes approximately equal to those observed 14 km inland near the cliff edge ground tilt dominates the observed large relative to vertical cross shore acceleration at infragravity frequencies contributes significantly to cross shore acceleration at swell frequencies and is a small fraction of cross shore acceleration at higher frequencies

quantifying 40 years of rockfall activity in yosemite valley with historical structure from motion photogrammetry and terrestrial laser scanning abstract rockfalls and rockslides are often dominant geomorphic processes in steep bedrock landscapes but documenting their occurrence can be challenging requiring frequent monitoring and well resolved spatial data repeat application of remote sensing methods such as terrestrial laser scanning tls and structure from motion sfm photogrammetry can detect even very small rockfalls but typically these acquisitions span only years and may not record rockfall activity representative of longer term rates of cliff erosion inventory databases can extend rockfall records but are commonly incomplete and prone to observation bias we employed tls and sfm on two adjacent cliffs el capitan and middle brother in yosemite valley integrating semi annual data collections from 2010 to 2017 with historical archival sfm models derived from oblique photographs taken in 1976 comparing the 1976 sfm models against more recent data allows for more accurate and precise rockfall detection and volume measurement over a 40 year period change detection indicates that 235 rockfalls occurred from the two cliffs more than twice as many events as are recorded in yosemite s inventory database although individual rockfall volumes reported in the inventory database vary from those measured by sfm tls reported cumulative volumes are similar to measured volumes likely because the large volume events that account for most of the cumulative volume tend to be widely observed and well documented volume frequency relationships indicate that the cliffs erode predominantly by less frequent larger volume rockfalls at rates of 0 9 to 1 7 mm yr our study demonstrates how integrated sfm and tls measurements especially utilizing sfm models derived from historical imagery allow detection and quantification of rockfalls spanning several decades complementing and improving inventory databases informing rockfall hazard assessment and providing longer term rates of cliff erosion

the campanian plain and phlegrean fields structural setting from potential field data abstract a boundary analysis of the gravity and magnetic fields of the phlegrean fields volcanic area and of the surrounding campanian plain reveals a complex structural setting the campanian plain results well defined from sharp density boundaries a set of major e w lineaments occurs within the plain we derive a framework of the structural control to the volcanological evolution of campanian plain which appears strongly influenced by a set of ne sw lineaments bordering the acerra depression the density and magnetization boundaries of the phlegrean fields are significantly consistent both indicating for the collapsed phlegrean caldera an area considerably less extended than that based on previous geologically defined models many other structures are evidenced in the phlegrean area often with agreement between density and magnetization boundaries inside the caldera a strong consistence between the structures we identified and recent seismicity has been noted

rock coasts with particular emphasis on shore platforms rock coasts are one of the most common elements of the world s littoral zone and they are often important sources of sediment for estuaries and beaches economic development growing populations and the potential effects of rising sea level provide a practical need to understand the dynamics of these coasts although there have been significant advances in our understanding of rocky coastal systems further progress has been hindered by a lack of researchers and by the often imperceptible changes that generally occur within human time scales this paper reviews rock coast processes and landforms in a variety of morphogenic environments one of our most fundamental challenges is to determine the degree to which rock coasts are contemporary rather than inherited features from the quaternary when changes in sea level and climate were responsible for marked variations in the nature intensity and elevational distribution of the marine and subaerial processes that sculpture rock coasts

comparison of short term seacliff retreat measurement methods in del mar california article i nfo seacliff retreat has been variously characterized as the recession rate of the cliff top of the cliff base and as the bulk recession rate based on volumetric changes of the entire cliff face here these measures of retreat are compared using nine semi annual airborne lidar light detection and ranging surveys of southern california seacliffs changes in the cliff base location where the steeply sloping cliff face intersects the beach include cliff retreat owing to basal erosion but also reflect changes in beach sand level and basal talus deposits averaged over the 2 5 km alongshore study span the cliff base actually prograded seaward about 12 cm during the 4 year study cliff top change was dominated by few relatively large several meters localized retreats cliff face changes that include failures and deposits anywhere on the cliff profile had a relatively small mean magnitude compared to cliff top changes and were more widely distributed alongshore however the similar alongshore averaged cumulative cliff top and net bulk cliff face end point retreat 14 and 19 cm respectively suggest that mean cumulative cliff top retreat can potentially be a viable surrogate for mean net cumulative cliff wide erosion and vice versa over relatively short time periods cliff face erosion occurred repeatedly at some locations confirming the presence of seacliff erosion hot spots during the study period

petrographic and melt inclusion constraints on the petrogenesis of a magmaclast from the venetia kimberlite cluster south africa abstract kimberlitic magmaclasts are discrete ovoid magmatic fragments that formed prior to emplacement from disrupted kimberlite magma to provide new constraints on the origin and evolution of the kimberlite melts we document the mineralogy and petrography of a magmaclast recovered from one of the ca 520 ma venetia kimberlites south africa the sample bi9883 has a sub spherical shape and consists of a 10 mm diameter central olivine macrocryst surrounded by porphyritic kimberlite the kimberlitic material consists of concentrically aligned altered olivine phenocrysts set in a crystalline groundmass of calcite chromite perovskite phlogopite apatite ilmenite titanite sulphides rutile and magnetite along with abundant alteration phases i e serpentine talc and secondary calcite these features are typical of archetypal hypabyssal kimberlites we examined primary fluid melt inclusions in chromite perovskite and apatite containing a diversity of daughter phases chromite and perovskite host polycrystalline inclusions containing abundant alkali carbonates i e enriched in k na ba sr phosphates na k chlorides sulphides and equal to lesser quantities of olivine phlogopite and pleonaste in contrast apatite hosts polycrystalline assemblages with abundant alkali carbonates and na k chlorides and lesser amounts of olivine monticellite and phlogopite numerous solid inclusions of shortite na 2 ca 2 co 3 3 na sr carbonates and apatite occur in groundmass calcite along with fluid inclusions containing daughter crystals of na carbonates and na chlorides the primary inclusions in chromite perovskite and apatite are considered to represent remnants of fluid s melt s trapped during crystallisation of the host minerals whereas the fluid inclusions in calcite are probably secondary in origin the component proportions of these primary fluid melt inclusions were estimated in an effort to constrain the composition of the evolving kimberlite melt these estimates suggest melt evolution from a silicate carbonate kimberlite melt that became increasingly enriched in carbonates phosphates alkalis and chlorides in response to the fractional crystallisation of constituent minerals i e olivine to apatite the concentric alignment of crystals around the olivine kernel and ovoid shape of the magmaclast can be ascribed to the low viscosity of the kimberlite melt and rapid rotation whilst in a liquid or partial crystalline state or to progressive layer by layer growth of the magmaclast although the mineralogy of our sample is similar to hypabyssal kimberlites worldwide it differs from hypabyssal kimberlite units in the main venetia pipes which contain monticellite phlogopite rich assemblages and segregationary matrix textures therefore magmaclast bi9883 probably originated from a batch of magma distinct from those that produced known hypabyssal units within the venetia kimberlite cluster

rock coast geomorphology recent advances and future research directions there have been considerable advances in rock coast research in the past decade as measured in terms of the number of active researchers and in the number of research papers being produced this review although not exhaustive highlights many of the improvements that have been made in our ability to identify and measure the processes shaping rock coasts at a range of spatial and temporal scales we review how researchers are experimenting with new techniques grappling with quantifying the effects of multiple processes on resultant landforms and exploring how well rock coast systems relate to wider geomorphological and earth science debates recent research including those in this special issue aptly demonstrate the scientific benefits that can be accrued by studying rock coasts at a variety of spatial and temporal scales by considering the effect of the wide range of processes that operate on them and by the application of new measurement techniques and approaches despite these advances there is ample scope for future research which could profit from increasing collaboration with other coastal geomorphologists and allied earth science disciplines in order to identify and quantify linkages between rock coasts and other coastal systems it is also important that new research considers how rock coasts will respond to extreme events and to risks associated with changing climate and to how rock coast geomorphology might contribute beyond coastal science to wider debates in theoretical geomorphology

the role of groundwater in cliff instability an example at cape blanc nez pas de calais france cliff retreat in northern boulonnais is described the distribution of the amount of retreat is related to structural and topographic factors both control the runoff infiltration balance and therefore the mechanical behaviour of the rocks which determines the modes of failure the spatial variability of the retreat rate is explained but predicting the temporal variability of the retreat rate which is central to risk management is much more difficult rainfall and piezometric surface data enhanced a piston flow mechanism during november 2000 the result of its occurrence on the stability of the cliff and conditions of its recurrence are examined with a view to better understanding the rate of recession of coastal cliffs and wiser management of risk copyright 2005 john wiley sons ltd

statistical and empirical analyses of the triggers of coastal chalk cliff failure the triggering factors of rock falls remain unknown due to a lack of exhaustive regular and accurate surveys based on an inventory of 331 rock falls collected weekly between 2002 and 2009 from veules les roses to le treport upper normandy the relationships between coastal chalk cliff rock falls dates and geomorphological features and external factors commonly agreed as triggering rainfall temperature variations tide and wind are studied the combination of multivariate statistical and empirical analyses indicates that 1 cold and dry weather and high rainfall and high wind are the conditions most likely to trigger rock falls 2 the main triggering factors of rock falls are effective rainfall for rock falls mostly between 200 and 1400 m3 or larger than 10 000 m3 and coming from the whole cliff face freeze thaw cycles especially for rock falls smaller than 200 m3 and coming from the foot and top of the cliff face and marine roughness rock falls mainly smaller than 200 m3 and coming from the cliff foot however the contribution of each factor to triggering is difficult to determine because of combinations of factors 85 of 331 cases relays of processes and hysteresis phenomena in view of these first results it is still presumptuous to predict the location and time of triggering of rock falls however the statistical and naturalistic approaches adopted and the observations made in this study are from an original database and constitute a real starting point for the prediction and prevention of the hazard of coastal chalk cliff rock falls in upper normandy copyright 2015 john wiley sons ltd

modeling the erosion of cohesive clay coasts a model was developed to study the erosion of cohesive clay coasts in macro to non tidal environments the model shares some of the characteristics of previous models including the erosion of bare clay surfaces by wave generated bottom shear stresses and of mobile sediment covered surfaces by abrasion it differs from previous models however in several important ways the morphodynamics of beaches with clay foundations under different wave conditions are based on a previously developed model for beaches on rocky shore platforms sediment thickness along a beach profile is calculated at regular intervals and compared with the maximum thickness that could be moved at that location under prevailing wave conditions wave friction factors are determined where necessary according to the occurrence and morphology of ripples on the bottom in addition to abrasion and the effect of wave induced shear stresses on the clay bottom erosion by stresses generated by wave impact at the bluff foot and on the intertidal platform is calculated using an expression derived from hard rock coastal models tides are represented by their computed tidal duration values the amount of time each year that the water level falls within each 0 1 m vertical interval water depths are modified by wave setup and set down conditions several preliminary model runs were made the profiles were concave in the submarine zone and roughly linear in the intertidal zone equilibrium profiles developed which were maintained as they migrated landwards

ultradeep greater than 300 kilometers ultramafic upper mantle xenoliths geophysical discontinuities in earth s upper mantle and experimental data predict the structural transformation of pyroxene to garnet and the solid state dissolution of pyroxene into garnet with increasing depth these predictions are indirectly verified by omphacitic pyroxene exsolution in pyropic garnet bearing xenoliths from a diamondiferous kimberlite conditions for silicon in octahedral sites in the original garnets are met at pressures greater than 130 kilobars placing the origin of these xenoliths at depths of 300 to 400 kilometers these ultradeep xenoliths support the theory that the 400 km seismic discontinuity is marked by a transition from peridotite to eclogite

temporal and spatial variations of chalk cliff retreat in east sussex 1873 to 2001 spatial and temporal variations of chalk cliff retreat rates over a 130 yr period are examined for 22 km of the east sussex chalk coastline between brighton and belle toutetout lighthouse england data are derived from maps surveyed between 1873 and 1925 28 and air photographs dating from 1973 and 2001 the long term average cliff retreat rate over the period 1873 to 1973 is 0 36 m y 1 and from 1873 to 2001 is 0 35 m y 1 over the whole 23 km study area rates calculated over shorter time slices indicate a decline in cliff retreat 0 37 m y 1 between 1873 and 1925 28 0 35 m y 1 between 1925 28 and 1973 0 27 m y 1between 1973 and 2001 temporal variations are unlikely to be due to variations in precipitation and frost days though the relationship remains uncertain due to the resolution of available cliff retreat and climatic data changes in wave climate are small and cannot be responsible for the decline in cliff retreat the study suggests that the most important factors causing the measured decline in cliff retreat rates are firstly the loss of cliff toe beaches over time and secondly widening of the rocky shore platforms that front the cliffs some of the spatial variability in retreat rates can be explained by local variations in lithology

mixed mantle provenance diverse garnet compositions in polymict peridotites kaapvaal craton south africa garnet compositions are used to understand mantle petrogenesis and to reconstruct the lithostratigraphy of the shallow mantle 6 200 km however garnets in polymict peridotites from the kaapvaal craton s 2500 ma have a centimeter scale elemental and stable isotopic variability suggestive of a mixed mantle provenance the chemical heterogeneity of the garnets is similar to that reported from rocks sampled over a considerable depth and temperature range within the lower lithosphere for example garnets found in polymict peridotites are similar to garnets found in sheared and granular peridotites cold and hot lherzolites peridotitic p type diamond inclusions and garnets from polybaric 50 200 km peridotites i e spinel garnet and diamond facies these data indicate that the kaapvaal cratonic root has been disturbed by complex processes possibly associated with crack propagation and entrainment that juxtaposed garnet bearing lithologies of diverse petrogenesis provenance and depth this has preserved chemical disequilibrium in the high pressure minerals in what is in effect a mantle breccia possibly associated with kimberlite precursors

modeling cohesive clay coast evolution and response to climate change a model was used to study the evolution of cohesive clay coasts under different environmental and geological conditions and the effect of future climate change the model considered wave impact on the bluff and in the intertidal zone and bottom generated shear stresses and the protective and abrasive action of beach sediment in the intertidal and subtidal zones quasi equilibrium conditions developed in model runs with parallel slope retreat in the upper portion of the profiles and slope decline in the lower portions profile gradient below the low tidal level increased with the threshold shear stress for bottom erosion therefore rates of wave attenuation were lower in resistant than in weak materials and the intertidal zones were wider and more gently sloping the widest and gentlest intertidal zones developed in runs that had no sediment the largest waves played little role in platform development in part because of low frequency but mainly because they expend most of their energy in crossing wide turbulent surf zones the model suggested that rising sea level will usually result in accelerated rates of bluff recession especially if the rise is rapid simultaneous increases in the frequency of moderately large waves as opposed to the largest waves may also generate marked increases in erosion on bluffs and in intertidal and supratidal zones although erosion may be reduced at some elevations where there is beach sediment positive or negative changes in beach volume can increase or decrease rates of bluff erosion