bioerosion of intertidal limestone co clare eire 2 hiatella arctica abstract the boring bivalve hiatella arctica l is common in the lower intertidal and upper sublittoral zones of the carboniferous limestone coast of nw co clare eire age determinations using growth rings are discussed and boring rates are calculated from the relationships between age and depth of boring to range between 0 125 and 1 0 cm a 1 the significance of hiatella borings in weakening rock surfaces is discussed suggesting that death and colonisation cycles are more frequent than rock fracture cycles

biogeomorphology revisited looking towards the future although biogeomorphological research is well established with many studies on a range of two way interrelations between organisms and geomorphology in different environments there is little consensus over what constitutes biogeomorphology why it might be useful and where it is heading starting with definitions of core biogeomorphic processes we consider the need for future biogeomorphological studies to evaluate the crucial links between bioprocesses biological community dynamics and inorganic earth surface processes five key applications of biogeomorphological research are identified the roles of organisms in environmental reconstruction trace fossil analysis extraterrestrial geomorphology environmental engineering and the built environment some key research directions and methodological challenges for future biogeomorphological research include expanding the spatial and temporal coverage of datasets investigating the role of bioprocesses in landform development tackling scale issues investigating the relevance of nonlinear dynamical ideas to biogeomorphology and developing better sampling and monitoring techniques for bioprocesses

limpet erosion of chalk shore platforms in southeast england where the upper chalk reaches the coast in east sussex it gives rise to high cliffs and wide shore platforms limpets patella vulgata living on the platforms contribute significantly to platform downwearing by ingesting chalk as they graze and by excavating hollows homescars to which they return after feeding a series of experiments has been carried out to try to estimate rates of limpet erosion analyses of the calcium carbonate content of the faeces of captive limpets suggest that adult limpets consume about 9 g of chalk per year on the platforms as a whole limpets are probably responsible for an average of about 15 mm of surface lowering a year but in areas of high population density the rate may be as high as 49 mm a year the overall mean rate of platform lowering caused by all processes of weathering and erosion is estimated to be about 3 mm a year across the entire intertidal zone but where limpets are present in significant numbers the rate may be around 3 mm a year the implication is that limpets are responsible for an average of about 12 per cent of the downwearing in the areas they frequent and in areas of maximal population density may cause 35 per cent or more of the downwearing in their vicinity subsidiary experiments are described that assess the limitations of the faecal method of estimating limpet erosion

methane hydrate bearing sediments pore habit and implications abstract hydrate bearing sediments are relevant to the organic carbon cycle seafloor instability and as a potential energy resource sediment characteristics affect hydrate formation gas migration and recovery strategies we combine the physics of granular materials with robust compaction models to estimate effective stress and capillary pressure in order to anticipate the pore habit of methane hydrates as a function of the sediment characteristics and depth then we compare these results to an extensive database of worldwide hydrate accumulations compiled from published studies results highlight the critical role of fines on sediments mechanical and flow properties hydrate pore habit and potential production strategies the vast majority of hydrate accumulations 92 of the sites are found in fines controlled sediments at a vertical effective stress between z 400 kpa and 4 mpa where grain displacive hydrate pore habit prevails in the form of segregated lenses and nodules while permeation based gas recovery by depressurization is favored in clean coarse sediments gas recovery from fines controlled sediments could benefit from enhanced transmissivity along gas driven fractures created by thermal stimulation

scale issues in weathering studies a review of the major scale issues in weathering studies reveals concerns over the fundamental spatio temporal distributions of weathering phenomena as well as issues of upscaling microscope based observations and linking different scales of observations in explanations of landform development various strategies are proposed which can be used to tackle these issues many rooted in non linear dynamical systems ideas as an initial step spatio temporal scale distributions are estimated here for weathering processes landforms and controls based on a range of empirical data two case studies of phytokarst in grand cayman and blistering and scaling of building stones are presented to illustrate the types of data that might be used to establish more convincing scale linkages in weathering investigations

linking environmental regimes space and time interpretations of structural and functional connectivity connectivity as a concept has been increasingly part of discussions or explanations in hydrology geomorphology and ecology we address recent critiques of this approach by demonstrating how a refinement which distinguishes structural connectivity from functional connectivity can be used to explain patterns observed in very different environmental systems these systems are found in linkages between surface and subsurface flowpaths and the hyporheos in the river don a temperate river channel in yorkshire uk in surface and subsurface fluxes in agricultural land in the uk and in vegetation and surface conditions in a degrading environment at the sevilleta lter site in the semi arid southwest usa first we demonstrate long term geological and structural controls mediated by in channel processes second human organization of landscape elements is a significant control on runoff and erosion so that similar events can produce very different responses and vice versa third linkages between the removal of grass vegetation and runoff and erosion produce non linear and path dependent feedbacks which control the subsequent degradation of the landscape making the process difficult to reverse as a result of these studies we argue that even in cases where connectivity cannot be directly quantified at least at present this limitation does not prevent the concept from being a useful heuristic device for exploring responses of complex systems furthermore this result implies that an increasing need exists for disciplinary connectivity to investigate such systems

block removal and step backwearing as erosion processes on rock shore platforms a preliminary case study of the chalk shore platforms of south east england shore platforms frequently exhibit steps or risers facing seaward landwards or obliquely across shore a combination of soft copy photogrammetry ortho rectification geo referencing and field measurement of step height are linked in a gis environment to measure step retreat on chalk shore platforms at sample sites in the south of england over two periods 19732001 20012007 the methods used allow for the identification delineation and measurement of historic change at high spatial resolution the results suggest that while erosion of chalk shore platforms by step backwearing is highly variable it appears to be of similar magnitude to surface downwearing of the same platforms measured by micro erosion meters mems and laser scanning in a range equivalent to 00006 00050my 1 of surface downwearing this equates to annual chalk volume loss from the platforms by the two erosion processes combined of between 00012m3m 2 and 00100m3m 2 results from the more recent years data suggests that step retreat has variability in both space and time which does not relate solely to climatic variability the results must be viewed with caution until much larger numbers of measurements have been made of both downwearing and step erosion at higher spatial and temporal resolution

development of shore platforms on kaikoura peninsula south island new zealand ii the role of subaerial weathering the role of subaerial weathering in the development of shore platforms on kaikoura peninsula is investigated evidence for weathering came from a number of distinctive surface morphologies on platforms salt crystal growth water layer weathering and slaking schmidt hammer test data showed that weathering had occurred and that rock strength was reduced through weathering by as much as 50 weathering processes on shore platforms rely on repeated wetting and drying and for this reason the number of wetting and drying cycles was estimated it was found that the number of wetting and drying cycles depend not only on the pattern of tidal water levels but also on algae growth and desiccation the number of cycles ranged from 104 to 379 per year at elevations low in the tide range fewer cycles occurred the greatest number occurring between the peaks of spring and neap tides and where rainfall adds to the number the zone of most cycles was estimated to occur between 0 6 and 0 9 m above mean sea level on the more landward margins of platforms it is at these elevations that the highest rates of erosion occur based on these results it is argued that the development of shore platforms at kaikoura results from subaerial weathering caused by repeated wetting and drying this is contrary to the view that shore platforms result from marine erosion

reconceptualising the role of organisms in the erosion of rock coasts a new model attempts to understand the morphodynamics of rock coasts focus on the nature and rate of erosion and how this influences the evolution of coastal profiles over century to millennial timescales biological contributions to this process are often ignored or treated in a rather simplistic way as merely producing microscale decreases in rock strength using a combination of field observations and literature review we address two key issues hampering a more rounded assessment of biological impacts erosion of coastal rocks firstly we reconceptualise the biological contributions to erosion of rock coasts into direct and facilitative types and secondly we discuss the need for more appropriate reporting of rates of bioerosion for direct bioerosion this means clearly documenting the percentage of platform surfaces affected by bioerosive agents and quantifying the volume of material eroded and the amount of fine sediment produced for facilitative bioerosion we must quantify the roles of biota in changing the material properties of rocks creating or altering surface morphologies and or weakening joint boundaries in this way facilitative bioerosion is one of several processes mediating geomorphic alteration of rock surfaces contributing to the production of landforms and or reducing the resisting force of rock subsequently we build on these ideas to produce a new conceptual model which more accurately portrays the multiple and cross scalar ways that biological processes notably bioerosion influence the resistance of coastal rocks to erosive forces such a model provides a stronger basis for numerical modelling and understanding the morphodynamics of rock coasts in the future and allows a quantitative assessment of the role of biota

new insights on the relative contributions of coastal processes and tectonics to shore platform development following the kaikōura earthquake we describe the immediate impact of the 14 november 2016 kaikoura magnitude 7 8 mw earthquake on shore platforms and cliffs around kaikoura peninsula the earthquake caused an instantaneous uplift of 1 01 m of the peninsula we resurveyed 7 profiles previously used for erosion monitoring and observed changes in the configuration of the shoreline the coseismic uplift has fundamentally changed the process regime operating on the platforms and altered the future trajectory of shore platform and cliff development our observations highlight the interplay of waves weathering biology and tectonics at this location tectonism strongly modulates the process regime driving instantaneous changes in morphology and altering rates and patterns of erosion finally the uplift of the kaikoura coast has implications for changing resilience to climate change and sea level rise

measuring erosion with the micro erosion meter contributions to understanding landform evolution abstract we review the contribution made to understanding landform evolution through the use of the micro erosion meter mem and the variant the traversing micro erosion meter tmem the mem has allowed the direct measurement of bedrock erosion in terrestrial and coastal settings as well as of building stone as recorded in mem measurements world wide the average rate of surface lowering on shore platforms is 1 486 mm a 1 and on terrestrial rock surfaces measured lowering rates are on average 0 903 mm a 1 reported means obscure significant variation in rates from a range of environmental settings and lithologies the mem has in a number of examples allowed the identification of the contribution of individual processes in polygenetic settings particularly in shore platform studies the dynamic nature of rock weathering has been highlighted where the tmem has revealed rock surfaces swelling and contracting at time scales ranging from hours to years the mem will continue to provide useful data on erosion rates and processes but the most fruitful investigations will be those that combine the t mem with other techniques that transcend time and space scale issues in erosion and process measurement

a conceptual framework for dryland aeolian sediment transport along the grassland forest continuum effects of woody plant canopy cover and disturbance article i nfo aeolianprocesses are of particular importance in dryland ecosystems where ground cover is inherently sparse because of limited precipitation dryland ecosystems include grassland shrubland savanna woodland and forest and can be viewed collectively as a continuum of woody plant cover spanning from grasslands with no woody plant cover up to forests with nearly complete woody plant cover along this continuum the spacing and shape of woody plants determine the spatial density of roughness elements which directly affects aeolian sediment transport despite the extensiveness of dryland ecosystems studies of aeolian sediment transport have generally focused on agricultural fields deserts or highly disturbed sites where rates of transport are likely to be greatest until recently few measurements have been made of aeolian sediment transport over multiple wind events and across a variety of types of dryland ecosystems to evaluate potential trends in aeolian sediment transport as a function of woody plant cover estimates of aeolian sediment transport from recently published studies in concert with rates from four additional locations two grassland and two woodlandsites arereportedhere thesynthesisofthesereportsleadstothedevelopmentofanewconceptual framework for aeolian sediment transport in dryland ecosystems along the grassland forest continuum the findings suggest that 1 for relatively undisturbed ecosystems shrublands have inherently greater aeolian sediment transport because of wake interference flow associated with intermediate levels of density andspacingofwoodyplants and 2 fordisturbedecosystems theupperboundforaeoliansedimenttransport decreases as a function of increasing amounts of woody plant cover because of the effects of the height and density of the canopy on airflow patterns and ground cover associated with woody plant cover consequently aeolian sediment transport following disturbance spans the largest range of rates in grasslands and associated systems with no woody plants e g agricultural fields an intermediate range in shrublands and a relatively small range in woodlands and forests these trends are consistent with previous observations relating large rates of wind erosion to intermediate values for spatial density of roughness elements the framework for aeolian sediment transport which isalso relevanttodust fluxes wind erosion andrelatedaeolianprocesses is applicable to a diverse suite of environmental challenges including land degradation and desertification dust storms contaminant transport and alterations of the hydrological cycle

implications of the saltation abrasion bedrock incision model for steady state river longitudinal profile relief and concavity the saltation abrasion model predicts rates of river incision into bedrock as an explicit function of sediment supply grain size boundary shear stress and rock strength here we use this experimentally calibrated model to explore the controls on river longitudinal profile concavity and relief for the simple but illustrative case of steady state topography over a wide range of rock uplift rates we find a characteristic downstream trend in which upstream reaches are close to the threshold of sediment motion with large extents of bedrock exposure in the channel bed while downstream reaches have higher excess shear stresses and lesser extents of bedrock exposure profile concavity is most sensitive to spatial gradients in runoff and the rate of downstream sediment fining concavity is also sensitive to the supply rate of coarse sediment which varies with rock uplift rate and with the fraction of the total sediment load in the bedload size class variations in rock strength have little influence on profile concavity profile relief is most sensitive to grain size and amount of runoff rock uplift rate and rock strength influence relief most strongly for high rates of rock uplift analysis of potential covariation of grain size with rock uplift rate and rock strength suggests that the influence of these variables on profile form could occur in large part through their influence on grain size similarly covariation between grain size and the fraction of sediment load in the bedload size class provides another indirect avenue for rock uplift and strength to influence profile form copyright 2008 john wiley sons ltd

shore platform abrasion in a para periglacial environment galicia northwestern spain abstract the schmidt rock test hammer was used to study the effect of abrasion on shore platforms in galicia northwestern spain on platforms where tidally induced weathering salt wetting and drying etc is dominant rock strength is significantly lower than in areas where abrasion is or has been active in the recent past this suggests that abrasion removes weathered surface material exposing the stronger less weathered rock below abrasion downwearing measured with a transverse micro erosion meter ranged between 0 13 and 1 8 mm yr 1 over the last year most active abrasion occurs in the upper part of the intertidal zone but weathering is slowly destroying formerly abraded surfaces at lower elevations these abandoned surfaces were abraded by materials supplied by erosion of fluvio nival and periglacial slope deposits that covered or partially covered parts of the galician coast during the middle and late weichselian during the holocene rising sea level and erosion of the slope deposits caused the abrasion zone to gradually migrate up to its present position near the high tidal level the spatial and temporal role of abrasion on this coast is therefore closely associated with the exhumation and inheritance of ancient platform surfaces from beneath weichselian deposits

bioerosion of intertidal limestone co clare eire 3 zonation process and form abstract scanning electron microscope photographs show that perforation by boring algae was the dominant agency in bioerosion in the mid intertidal with lichen penetration occurring in the upper intertidal and sponge boring in the lower chemical data showed that dissolution was possible but sem observations suggested that it was of limited importance dominating micro surface form only in pools and the lower intertidal if algal and other biological covers were absent abrasion was also only locally important meso scale form is interpreted in terms of the vertical distribution of bioerosive organisms as influenced by the presence or absence of structural benches slopes occurring within a bioerosive zone were dominated by forms produced by the particular organisms present

decadal scale micro erosion rates on shore platforms abstract knowledge of the long term rates of erosion of shore platforms are needed to assist modeling platform development understand rates and modes of development and decipher issues of inheritance from former sea level few studies report rates from more than 2 years of monitoring we report decadal scale erosion rates using both a micro erosion meter and a traversing micro erosion meter with measurements from 30 years and 10 years respectively gross mean surface lowering rates measured over 10 years with a traversing micro erosion meter were 0 901 s e 0 116 mm yr compared with 1 130 s e 0 217 mm yr over two years over thirty years 1973 2003 12 micro erosion meter sites provide a mean surface lowering rate of 1 09 s e 0 126 mm yr compared to 1 43 s e 0 128 mm yr calculated over twenty years 1973 1993 from 15 bolt sites and 1 53 s d 1 45 mm yr from 31 bolt sites rates calculated over longer time periods are reduced compared to short term rates as a result of faster eroding bolt sites being removed from the data set comparison of means between short and long time periods for existing bolts show no significant difference that is short term measurements over two years are representative of decadal scale erosion rates in fact decadal scale rates may under represent rates of platform development because of the loss of faster eroding bolt sites the loss of such bolts means that obtaining long term erosion rates is problematic future modeling of shore platform development can use mem rates with more certainty but we recommend using higher rates from shorter term studies unless longer records are complete

rock surface millimetre scale roughness and weathering of supratidal mallorcan carbonate coasts balearic islands rock surface millimetre scale roughness and weathering of supratidal mallorcan carbonate coasts balearic islands

exploring the influence of biofilm on short term expansion and contraction of supratidal rock an example from the mediterranean previous geomorphological investigations using the traversing micro erosion meter tmem have identified daily and hourly contractions and expansions of littoral rock on a range of lithologies while organic influences on these patterns have been inferred this has rarely been tested in a controlled way here a tmem was used to measure micro scale mm topographic changes on supratidal limestone of the massif des calanques southern france four tmem monitoring sites each 64 cm2 were set up in total two in the calanque de morgiou and two in the presqu ile de cassis on both shores one tmem bolt site was positioned on bare rock and the other on colonized rock tmem data were collected and the surface micro topography mapped for each site at two hourly intervals from early morning to late evening across one day in mid summer significant relative expansion and contraction was observed between measurement periods at all four sites regardless of biofilm colonization p 0 001 in all instances and sometimes between adjacent zones on the rock surface at a scale of centimetres rock with and without biofilm behaved broadly similarly but the magnitude of topographic change varied average movement from one interval to the next was 0 03 mm on bare sites and 0 06 mm on biofilm colonized sites as expected patterns of surface change related largely to insolation with greatest movement occurring in the morning and evening when thermal gradients were steepest interestingly the presence of a biofilm intensified rock expansion but delayed surface response to microclimatic variability we largely attribute this effect to biofilm influences on surface albedo and hypothesize that episodes of contraction and expansion are superimposed onto longer annual to decadal episodes of surface movement and downwearing short term tmem studies therefore need to be coupled with longer term seasonal and annual measurements to improve understanding of rock surface dynamics copyright 2014 john wiley sons ltd

development of shore platforms on kaikoura peninsula south island new zealand abstract the role of waves in shore platform development has been investigated on kaikoura peninsula by direct measurement of waves in deep water and on platforms at high tide this showed that the deepwater wave environment off the kaikoura peninsula is very energetic but the amount of energy delivered to platforms is very low in deep water wave power ranged from 5900 to 106 700 n m s 1 per m of crest when calculated from mean significant wave height and when calculated from maximum wave height it ranged from 31 400 to 5 370 000 n m s 1 per m of crest a comparison of deep water wave energy flux with wave energy flux at the high tide cliff of platforms showed that there was a reduction by as much as five orders of magnitude during storm conditions an analysis of the role of breaking waves revealed that these are ineffective as an erosional agent because the depth of water offshore causes breaking before waves arrive on platform surfaces depth of water controlling wave breaking causes larger storm waves to break further from shore preventing direct attack at the cliff base shear stresses and dynamic forces under waves were calculated from waves measured on shore platforms this showed that these forces never exceeded the compressive strength of the platform rocks at kaikoura it is concluded that wave forces are not directly capable of causing erosion on shore platforms at kaikoura

a new technique for non destructive field measurement of rock surface strength an application of the equotip hardness tester to weathering studies tafone like depressions have developed on the aoshima sandstone blocks used for a masonry bridge pier in the coastal spray zone a thin layer of partial granular disintegration was found on the surface in depressions to evaluate quantitatively the strength of the thin weathered layer the hardness was measured at the surface of the sandstone blocks using both an equotip hardness tester and an l type schmidt hammer comparison of the two testing results indicates that the equotip hardness value is more sensitive in evaluating the strength of a thin layer of weathered surface rock than the schmidt hardness value by applying two methods i e both the repeated impact method and the single impact method the equotip tester can evaluate the strengths of fresh internal and weathered surficial portions of rocks having a thin weathering layer comparison of the two strengths enables evaluation of strength reduction due to weathering copyright 2007 john wiley sons ltd

microbial geomorphology a neglected link between life and landscape abstract whilst recognition is increasing that life and landscapes are intimately related as evidenced by growing research into ecosystem engineering biogeomorphology and allied topics the microbial contribution to such interactions has been relatively neglected a revolution in environmental microbiology based on molecular techniques is now driving a reconsideration of the role of microbial processes in geomorphology at all scales recent research illustrates the hitherto unknown microbial diversity present in many extreme geomorphic environments such as hyperarid deserts subglacial lakes hot springs and much richer microbial life than previously suspected within the soils and sediments that blanket most other landscapes such microbial communities have been found to play important geomorphic roles across a wide range of environments notably in weathering precipitation of minerals and protecting surfaces from erosion these geomorphic roles can also be conceptualised as examples of ecosystem engineering and can pave the way for further plant geomorphology and zoogeomorphology processes three key aspects which emerge from a review of microbial influences on earth surface processes are a that microbes play roles on a continuum from full control to passive involvement b that complex and widespread communities of microorganisms are involved and c that microbial activity usually affects several earth surface processes at once examples of the contribution of microbial life to geomorphology over long medium and short timescales suggest that microorganisms play key geomorphological roles in two major situations on the cusp between stable states and in extreme environments where higher plant and animal life is limited and many abiotic processes are also constrained the dominant link between microbial life and geomorphology appears to take on different forms depending on the timescale under consideration with a stabilising microbial role apparent over short timescales being replaced by a denudational role over longer timescales further research involving microbiologists and geomorphologists is now needed to address three main questions i e under what conditions are microbial and geomorphological processes most closely linked what scale issues surround links between microbes and geomorphology and how do microbiological processes underpin broader biogeomorphological interactions

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

bioerosion of intertidal limestone co clare eire 1 paracentrotus lividus abstract the boring sea urchin paracentrotus lividus is widely distributed in the mid and lower intertidal zones on carboniferous limestone in co clare eire erosion rates have been estimated from the measurement of excavation depth and the counting of growth rings on the test shell the rates ranged from 0 25 1 5 cm a 1 on an exposed shore to 0 1 0 cm a 1 on a sheltered site larger older individuals were commoner on the exposed site the distribution activities and geomorphological significance of the organisms are discussed together with the validity of the procedures adopted to estimate erosion rates it is clear that paracentrotus is a major factor in pool deepening in the mid intertidal zone and in weakening the rock mass in the lower intertidal especially when paracentrotus erosion rates are compared with general surface lowering rates of 0 2 mm a 1

geomorphologic equifinality a comparison between shore platforms in hoga kusten and faro sweden and the vale of glamorgan south wales uk this paper presents a case study comparing shore platforms of the same lithology and different rock structures limestone with those of different lithologies but similar rock structures limestone dolerite in wales and sweden results of this study illustrate that different erosion mechanisms i e wave action and ice scour produce similar erosion products and meso scale cm m landforms i e stepped shore platforms in structurally similar lithologies in contrast lithologically similar rocks i e limestones generate different meso scale landforms and shore platform morphologies thus structural controls appear to be more critical than lithological controls in generating meso scale erosion products such as rock blocks in this comparative study the similarities in the meso scale geomorphology appear to be caused by uniform rock structure i e rock hardness joint density spacing of bedding horizontal jointing and the slope and direction of bedding horizontal jointing in relation to the sea blocks produced by the jointing have been eroded by high energy waves in the case of wales and drifting sea ice in the case of one of the swedish sites meanwhile different rock structures in a similar lithology i e limestone resulted in very different landforms under the same environmental conditions as the previous example as such this research also provides observational evidence supporting the concept of equifinality

ecosystem engineers and geomorphological signatures in landscapes abstract biogeomorphologists study the roles of biota in landscape formation and decay ecologists interested in ecosystem engineering study environmental change caused by biota and the consequences for the engineer other organisms and ecological processes the interface is geomorphological change an interface both are aware of but study somewhat independently and differently interaction and integration among the two fields is the goal of this special issue here i take an ecological perspective of geomorphological change caused by ecosystem engineers in patches within landscapes that i hope can help facilitate this goal i ask the following general questions when will an ecosystem engineering species create a geomorphological signature in a landscape what in qualitative terms is such a signature how can the signature be estimated and how long will it last what engineer attributes and ecological factors will determine signature change what creates complications how do the answers inform whether or not life leaves a geomorphological signature to attempt answers i develop a provisional general theory of ecosystem engineering signatures that draws on and integrates a geomorphological foundation of balance between formation and decay landscape patch dynamics a general framework for ecosystem engineering and empirical studies i treat a landscape engineering signature as the balance of rates of formation f and rates of decay d across patches whose ratio value f d can be transformed 1 intermediate 1 or untransformed

predicting coastal cliff erosion using a bayesian probabilistic model abstract regional coastal cliff retreat is difficult to model due to the episodic nature of failures and the along shore variability of retreat events there is a growing demand however for predictive models that can be used to forecast areas vulnerable to coastal erosion hazards increasingly probabilistic models are being employed that require data sets of high temporal density to define the joint probability density function that relates forcing variables e g wave conditions and initial conditions e g cliff geometry to erosion events in this study we use a multi parameter bayesian network to investigate correlations between key variables that control and influence variations in cliff retreat processes the network uses bayesian statistical methods to estimate event probabilities using existing observations within this framework we forecast the spatial distribution of cliff retreat along two stretches of cliffed coast in southern california the input parameters are the height and slope of the cliff a descriptor of material strength based on the dominant cliff forming lithology and the long term cliff erosion rate that represents prior behavior the model is forced using predicted wave impact hours results demonstrate that the bayesian approach is well suited to the forward modeling of coastal cliff retreat with the correct outcomes forecast in 70 90 of the modeled transects the model also performs well in identifying specific locations of high cliff erosion thus providing a foundation for hazard mapping this approach can be employed to predict cliff erosion at time scales ranging from storm events to the impacts of sea level rise at the century scale

on the role of discontinuities in mediating shore platform erosion in this paper we quantitatively demonstrate that dominant erosion processes on different shore platforms can be explained in part by geological properties we selected sites with a considerable history of rock coast geomorphology study to evaluate whether geological data can improve our understanding of spatial variations in erosion between sites schmidt hammer tests and discontinuity data were collected on blue lias limestone shore platforms in wales uk and sandstone platforms in victoria australia significant differences in joint spacing persistence of discontinuities and block size were found between the australian and welsh study sites these data were related to evidence of meso scale erosion to examine how geological contingency influences the nature and scale of erosion processes and thresholds this study quantitatively demonstrates that discontinuities play a fundamental role in altering rock resistance the findings of this research have important implications for the design of rock coast erosion studies concerned with measuring rates of change and determining the relative contributions of different processes to platform development

two hourly surface change on supra tidal rock marengo victoria australia a traversing micro erosion meter was used to measure rock surface micro topography over 40 cm2 on a supra tidal cliff face from early morning to late evening in late spring from 06 00 hours to 22 00 hours the relative heights of 188 coordinates were obtained using the meter at 2 hour intervals resulting in a data set of 1607 readings monitoring shows that rock surfaces are dynamic entities with significant rise and fall relative to the first measurement at shorter timescales than previously reported the maximum positive rise between readings was 0 261 mm and lowering was 0 126 mm the pattern of change did not relate as expected to environmental variables such as temperature or insolation rather the surface showed greater surface change in the early morning and late afternoon it is hypothesized that this pattern relates to the expansion and contraction of lichen thalli as moisture is absorbed during higher humidity in the morning and late afternoon the implications of these results for weathering studies are considered copyright 2006 john wiley sons ltd

the use of the schmidt hammer and equotip for rock hardness assessment in geomorphology and heritage science a comparative analysis rapid field based measurements of rock hardness are of use in investigating many geomorphological and heritage science problems several different methods are now available for taking such measurements but little work has been done to assess their comparability and strengths and weaknesses we review here the capabilities of two types of schmidt hammer classic n type and silver schmidt bl type alongside two types of equotip standard type d and piccolo for investigating rock hardness in relation to rock weathering on various types of sandstone and limestone as well as basalt and dolerite whilst the two schmidt hammers and the two equotips show comparable results when tested at 15 individual sites interesting differences are found between the equotip and schmidt hammer values which may reveal information about the nature of weathering on different surfaces operator variance is shown to be an issue in particular for the equotip devices which also exhibit higher variability in measurements and necessitate larger sample sizes carborundum pre treatment also has varying effects on the data collected depending on the nature of the surface studied the equotip devices are shown to be particularly useful on smaller blocks and in situations where edge effects may affect schmidt hammer readings we conclude that whilst each device contributes to geomorphological research they do not necessarily produce comparable information indeed using schmidt hammer and equotip in combination and looking at any differences in results may provide invaluable insights into the structure of the near surface zones and the nature of weathering processes copyright 2010 john wiley sons ltd

geological controls on boulder production in a rock coast setting insights from south wales uk abstract we investigate some of the geological controls on boulder size using a heterogeneous outcrop of blue lias limestone discontinuity and predicted boulder size data were collected on different layers of blue lias limestone on a shore platform in wales united kingdom significant differences in joint spacing were found between the four layers examined and significant differences in the predicted boulder size were found between many of the ten stratigraphic layers examined predicted boulder size ranged from 0 18 to 4 00 m measured on the longest axis these data demonstrate that the shape and size of boulders liberated from the platform is dependent on which layer of limestone is at the surface since the size of boulders varies between layers depending on the thickness of beds and joint spacing the magnitude of wave energies required to detach entrain and transport boulders must vary boulder erosion is therefore geologically contingent and highly variable through time and space this variability requires us to develop methods to predict where boulder scale erosion is likely to occur and what wave conditions are required to add these materials to the sediment supply we therefore considered the reliability of predictions of boulder size for two layers examined layers 19 and 24 predicted boulder sizes were compared with boulders recently detached by storm waves i e within 2 5 months of detachment from the same layer results show that boulder volume was statistically similar between predicted and actual boulders and either the long or intermediate axis measurements were statistically similar variations between predicted and actual boulder axis lengths are attributed to the sampling design for measuring predicted boulders variable detachment processes and the rapid breakdown of rock masses post detachment our results demonstrate that in locations where repeated entrainment transport and boulder breakdown are observed loose boulder size may not be a reliable means of reconstructing wave energies required to detach entrain and transport boulders

fluvial geomorphology a perspective on current status and methods fluvial geomorphology seeks to study river landform history understand formative processes and predict changes using a combination of field observation experimental studies and numerical models a resurgence in fluvial geomorphology is taking place fostered for example by its interaction with river engineering and the availability of new analytical methods instrumentation and techniques these have enabled development of new applications in river management landscape restoration hazard studies river history and geoarchaeology this paper presents a perspective on recent advances in fluvial geomorphology and introduces a selection of papers presented during the fluvial geomorphology and palaeohydrology session within the sixth international conference on geomorphology held in zaragoza spain in september 2005