lithological control on the elevation of shore platforms in a microtidal setting the shore platforms on shag point southern new zealand are quasi horizontal surfaces and are developed between supratidal and low water spring levels a range of morphologies occur with more exposed platforms having a distinct low tide cliff in contrast to low tide surfaces where the seaward edge is buried beneath rubble and macro algal growth the platforms range in width from 20 to 80 m and are eroded into late cretaceous early tertiary fine marine sandstones and mudstones shore platforms have formed in two principal lithological units a homogeneous unit that is characterized by few discontinuities and a fractured unit with joints spaced about 0 5 m apart rock hardness is low in both units l type schmidt hammer rebound values of 31 4 and there is little systematic variation in values between the two units in which platforms have developed case hardened concretions within the sandstone are significantly harder than surrounding rock and cause local relief of metre scale as the spherical diagenetic features are eroded from the bedrock they do not however appear to affect broad scale platform geometry joints within the bedrock are a primary control on platform elevation platforms formed in jointed rock occur at the lower portion of the intertidal zone in contrast to platforms formed in unjointed bedrock in which horizontal surfaces occur at or above mean high water spring tide level rock structure therefore appears to be the primary determinant factor of platform geometry at shag point copyright 2006 john wiley sons ltd

geomorphic and biological indicators of paleoseismicity and holocene uplift rate at a coastal normal fault footwall western corinth gulf greece abstract the westernmost part of the gulf of corinth greece is an area of very fast extension and active normal faulting accompanied by intense coastal uplift and high seismicity this study presents geomorphic and biological evidence of holocene coastal uplift at the western extremity of the gulf where such evidence was previously unknown narrow shore platforms benches and rare notches occur mainly on holocene littoral conglomerates of uplifting small fan deltas they are perhaps the only primary paleoseismic evidence likely to provide information on earthquake recurrence on coastal faults in the specific part of the rift whereas dated marine fauna can provide constraints on the average holocene coastal uplift rate the types of geomorphic and biological evidence identified are not ideal and there are limitations and pitfalls involved in their evaluation in a first approach 5 uplifted paleoshorelines may be identified at 0 4 0 7 1 0 1 3 1 4 1 7 2 0 2 3 and 2 8 3 4 m a m s l probably forming after 1728 or 2250 cal b p a most conservative estimate for the average coastal uplift rate during the late holocene is 1 6 or 1 9 mm yr minimum with different amounts of reservoir correction some of the obtained radiocarbon ages of lithophaga sp allow for much higher holocene uplift rates of the order of 3 4 mm yr which cannot be discarded but require further research that the identified paleoshoreline record corresponds to episodes of coastal uplift only cannot be demonstrated beyond all doubt yet it appears the most likely interpretation given the geological and active tectonic context and present knowledge on eustatic sea level fluctuations in the mediterranean proving that the documented uplifts were abrupt i e arguably coseismic is equally difficult but rather probable five earthquakes in the last ca 2000 yr on the coastal fault zone that is responsible for the uplift compare well with historical seismicity and the results of recent on fault paleoseismological studies at the nearby eliki fault zone exact amounts of coseismic uplift cannot be determined precisely unless the rate of non seismic uplift of northern peloponnesus at the specific part of the corinth rift is somehow constrained

downwearing rates of vertical limestone surfaces in the intertidal zone gulf of trieste italy abstract in 2007 we installed seven micro erosion meter stations on a vertical limestone slab located in the intertidal zone in the gulf of trieste italy in order to observe rock surface changes at elevations ranging between 0 75 m and 0 75 m m s l furlani et al 2010 in this paper we present the micro erosion metre mem data for most months between february 2008 and may 2013 and the traversing micro erosion metre tmem data collected twice a year since 2007 the mem and tmem data were consistent and indicated that the mean lowering rate ranged between 0 007 mm yr and 0 205 mm yr and 0 001 mm yr and 0 260 mm yr according to the elevation of the stations maximum downwearing rates were observed in the mid lower intertidal zone and decreased upward and downward the natural trend of erosion started in 2010 after 2 years of exposure when the slab formerly smoothed and not colonized by marine organisms started to be acclimated to the local environment after 2010 the erosion rate increased to a maximum of 0 31 mm yr this value can be more representative for long term studies and is similar to the downwearing rates locally collected on natural limestone surfaces this dataset represents the first collection of downwearing rates mainly measured using mems but also tmems on vertical limestone surfaces in an intertidal zone and provides interesting new information for addressing the debate on notch genesis and development the shape of a tidal notch has been found to be consistent with the distribution of erosion rates along the slab even if the present day notch was not surveyed in the gulf of trieste due to the local tectonic subsidence

shore platform downwearing in eastern canada the mega tidal bay of fundy abstract laboratory and field work was conducted to determine rates of surface downwearing on shore platforms at two sites in the bay of fundy canada these data are needed to assess and model the effect of downwearing mechanisms on platform evolution sandstone and basalt samples 900 were exposed to semidiurnal tidal cycles over 3 years using de ionized water or artificial sea water they were immersed for 1 6 or 11 h over each 12 h tidal cycle representing the lowest high lht mid and highest low hlt tidal levels respectively a further 600 samples were immersed in de ionized water or artificial sea water for 90 min every 1 2 or 3 weeks representing increasingly higher elevations above the lht level or exposed for 90 min every 1 2 or 3 weeks representing increasingly lower elevations below the hlt level these experiments ran for 12 months in the field surface downwearing was measured at 108 transverse micro erosion meter tmem stations over 2 to 6 year periods in the laboratory mean downwearing rates between the lht and hlt levels were 0 61 1 80 mm yr 1 in sandstones and 0 01 0 18 mm yr 1 in basalts rates were highest at the lht level rates decreased with elevation above the lht level and were uniformly low below the hlt level salt weathering was dominant above the lht level salt weathering and wetting and drying were important in sandstones between the lht and hlt levels but salts inhibited rock breakdown in basalts in the field the mean downwearing rate was 1 254 mm yr 1 in sandstones which was similar to the experimental data and 0 722 mm yr 1 in basalts which was much higher than in the experiments with artificial sea water but similar to the experiments with de ionized water there was no relationship in the field between downwearing rate and rock hardness or tmem station elevation

the effect of holocene changes in relative sea level on the morphology of rocky coasts abstract a mathematical wave and weathering model was used to study the effect of holocene changes in relative sea level rsl on rock coast development model runs were made for fast and slow eroding coasts in macro and mesotidal environments using holocene rsl records from sweden northeastern usa southwestern britain central japan western africa and southern australia a further series of otherwise identical runs were made with constant sea level changes in rsl determined the amount of time that marine processes have operated within the modern intertidal zone and rates of wave attenuation and erosion continue to be influenced by subtidal morphology that developed in most areas when rsl was rising to its present level the model suggested that although tidal range is also important holocene rsl changes promoted subhorizontal platform development in australasia and over much of the southern hemisphere and sloping platforms over much of the northern hemisphere shore platforms may have been partly inherited from earlier periods in the holocene when rsl was similar to today s nevertheless most platforms continue to be eroded at all tidal levels where geological and wave conditions are less favourable erosion in the lower intertidal zone has essentially terminated in areas where rsl rose to its present position whereas erosion only occurs today in the lower intertidal zone in places where rsl rose to above its present level in the middle holocene

long term remeasurements of micro erosion meter rates aldabra atoll indian ocean micro erosion meter sites installed on aldabra atoll indian ocean in 1969 to measure erosion rates in coastal and subaerial sites were remeasured in 1971 and again in 1982 the orders of magnitude of calculated erosion rates are comparable but the precise figures and patterns differ for subaerial sites the short term 1969 71 range of 0 11 0 58 mm a 1 compares with a long term 1971 82 range of 0 06 0 75 mm a 1 for coastal sites short term ranges of 0 002 7 5 mm a 1 compare with long term rates of 0 09 2 7 mm a 1 interpretation and extrapolation of short term data should only be made with caution

modeling the development of marine terraces on tectonically mobile rock coasts abstract a mathematical model was used to study the effect of glacially induced fluctuations in sea level on the formation of wave cut terraces on tectonically mobile rock coasts two deep water wave sets were used to calculate breaker height and depth which along with surf zone width bottom roughness and the gradient of the submarine slope dictated the force exerted at the shoreline an erosional force threshold was employed to represent the variable strength of the rocks the model also considered tidal range the time that the water level spent at each intertidal elevation and the protective effect of debris accumulation at the cliff foot three hundred runs were made with constant sea level and with different rates of rising and falling relative sea level rates of erosion increased with the rate of rising and falling sea level but eventually decreased in some runs with very rapid changes in relative sea level fifty five longer runs were also made with a quaternary sea level model that consisted of 26 glacial cycles representing the period from 2 million to 0 9 million years ago and nine cycles of approximately twice the amplitude and wavelength in the last 0 9 million years these runs were made on a landmass experiencing slow 0 11 mm yr 1 or fast 0 74 mm yr 1 positive or negative changes in the elevation of the land it was found that on rising landmasses erosional coastal terraces are formed during interglacial stages and on subsiding landmasses during glacial stages the number of terraces increased with the rate of uplift and subsidence and with the slope of the hinterland terrace gradient increased with tidal range and decreased with rock resistance the was an inverse relationship between terrace width and the strength of the rock

shore platform downwearing in eastern canada a 9 14 year micro erosion meter record abstract downwearing rates erosion in the vertical plane were measured with a micro erosion meter mem in eastern canada on an argillacious sub horizontal shore platform at mont louis in eastern quebec and on two sloping basaltic and sandstone platforms at respectively scots bay and burntcoat head in the bay of fundy nova scotia the original data covered a period from 2002 to 2009 this dataset was extended by measurements repeated at surviving mem stations in 2017 producing records ranging over 9 14 years depending on when each station was installed because of rapid surface downwearing many of the original mem stations were inoperable in 2017 especially at burntcoat head nevertheless data were obtained from 19 stations at burntcoat 35 of the 2009 original 25 at mont louis 83 of the original and 38 at scots bay 75 of the original for the stations at mont louis and scots bay that were still functioning in 2017 there were no significant differences in rates of downwearing over the shorter from station installation up to 2009 and extended periods from installation to 2017 mean rates of downwearing calculated from all the stations in each area declined through time however due to the loss of the more rapidly eroding stations a simple procedure which was proposed to compensate for this decrease produced mean downwearing rates that were broadly similar to those reported over the original measurement period there were significant relationships between downwearing rates and elevation r2 0 32 and downwearing rates and rock hardness r2 0 41 in the extended record at scots bay and a small but significant relationship between downwearing rates and rock hardness at mont louis r2 0 17 differences in downwearing rates across the platforms suggest that salt weathering and wetting and drying are dominant weathering mechanisms at scots bay and mont louis chemical weathering of the sandstone cementing agent and the premature removal of weathered grains by wave generated bottom currents may however be more important at burntcoat head

post eruptive morphological evolution of island volcanoes surtsey as a modern case study abstract surtsey is a small volcanic island in the vestmannaeyjar archipelago off the south coast of iceland the eruption leading to the island s emersion lasted for 3 5 yr 1963 1967 while destructive forces have been active for over 50 yr 1963 present day during which surtsey has suffered rapid subaerial and submarine erosion and undergone major morphological changes surtsey is a well documented modern example of the post eruptive degradational stage of island volcanoes and has provided the unique opportunity to continuously observe and quantify the effects of intense geomorphic processes in this paper we focus on coastal and marine processes re shaping the shoreline and shallow water portions of the surtsey complex since its formation and on the related geomorphological record analogies with the post eruptive morphological evolution of recently active island volcanoes at the emerging stage encompassing different climatic conditions wave regimes and geological contexts are discussed

geomorphology and the law of unintended consequences locke 1691 lessons from coastal weathering and erosion at prawle uk and kaikoura nz the sites of two field experiments based on micro erosion metering one in uk the other in new zealand were independently revisited respectively 33 and 17 years after installation at both sites natural weathering and erosion processes had been inadvertently interrupted by the experimental works leading to the development of new microscale landforms these are interpreted in the context of modifications of the controls on weathering processes leading to enhanced understanding of the processes themselves this has lessons for the geomorphologist in maintaining a long term watching brief over former experimental sites lest some unintended and potentially beneficial outcome has ensued this theme is embraced by the law of unintended consequences

quaternary carbonate record from the equatorial indian ocean and its relationship with productivity changes abstract the caco3 content in quaternary deep sea sediments from pacific and atlantic oceans have been suggested to respond differently to glacial interglacial cycles caco3 contents are highest during glacials in the pacific but highest during interglacials in the atlantic ocean it is not yet clear as to whether a pacific or an atlantic pattern of caco3 fluctuations dominates the indian ocean we have analyzed the ocean drilling program odp site 709a from the western equatorial indian ocean for the last 1370 ka to determine the relationships between percentages and fluxes of caco3 and quaternary paleoclimatic changes we also analyzed the coarse 25 m and fine 18 o of the planktonic foraminifera globigerinoides ruber this indicates that caco3 fluctuations at this site do not show either a pacific or an atlantic pattern of caco3 fluctuations fluxes of caco3 0 38 to 2 46 g cm 2 ka 1 in total sediment and ba al ratios 0 58 to 3 93 g cm 2 ka 1 show six fold variability through the last 1370 ka which points out that productivity changes are significant at this site fluxes of the fine caco3 component demonstrate a 26 fold change 0 02 to 0 52 g cm 2 ka 1 whereas the coarse caco3 component exhibit eight fold change 0 13 to 1 07 g cm 2 ka 1 this suggests that productivity variations of calcareous nannofossils are greater in comparison with the foraminifera on the other hand mean values of coarse caco3 fluxes are higher compared to those of fine caco3 which reveals that the foraminifera contribute more to the bulk caco3 flux than the calcareous nannofossils in the equatorial indian ocean

micro erosion meter measurements of rock wear on the otway coast of southeast australia abstract the use of the micro erosion meter mem has been refined by providing 1 a base plate on which to check the relationship of legs and probe and 2 a micrometer level to check the relationships of the three studs countersunk in the rock at each site along 50 km of the otway coast lines of mem stations were installed across shore platforms normal to the shore and surveyed to mean low water readings were made bimonthly from 1978 to 1980 average site downwear ranged from 0 02 to 1 8 mm yr 1 according to rock type and the amount of exposure to the almost continuous swell waves the results of this study combined with other information available are used to discuss the origin and evolution of otway coastal morphologies

long term shore platform surface lowering rates revisiting gill and lang after 32 years abstract in 1978 e d gill and j g lang installed 53 micro erosion meter mem sites on shore platforms along the otway coast in south eastern australia surface lowering rates were originally determined from 2 yr of measurements 1979 and 1980 and showed that the mean annual rate of lowering from all sites was 0 37 mm yr 1 we re measured these mem sites 32 yr after the first set of readings were taken in february 1979 we relocated 49 of the original 53 bolt sites and were able to measure 45 of them from the sites we measured the mean annual rate of shore platform lowering was 0 31 mm yr 1 rates of surface lowering on shore platforms are commonly reported from studies of only two or three years and only one other record exceeds 30 yr kaikoura peninsula nz 1 09 mm yr 1 in that case fewer than half of the original bolt sites were functioning because erosion had removed bolts along the otway coast rates of erosion are much slower hence the greater number of still readable sites after 32 yr compared to other micro erosion meter studies the rates reported here are at the lower end of the range of values from around the world but nevertheless consistent with rates from the otway coast and others in similar lithology we found no statistical difference between erosion rates calculated over 2 yr 1979 to 1980 and 32 1979 to 2011 years supporting the view that shore platform lowering rates measured over 2 yr are representative of decadal scales

short term rock surface expansion and contraction in the intertidal zone transverse micro erosion meter tmem stations were installed in rock slabs from shore platforms in eastern canada the slabs were put into artificial sea water for 1 6 or 11 hours representing high mid and low tidal areas respectively the tmems were used to record changes in surface elevation as the rocks dried during the remainder of the 12 h of a semi diurnal tidal cycle a similar technique was used on the same rock types at intertidal tmem stations in the field as the rocks dried during low tide argillite and basalt surface contraction was from 0 to 0 04 mm there was little surface expansion sandstones contracted by up to 0 03 mm in the field but there was almost no contraction in the laboratory argillite and basalt contraction tended to be greatest in the upper intertidal zone and to increase with rates of longer term surface downwearing but there was little relationship with rock hardness or air temperature and humidity changes in elevation at the same points at tmem stations in the laboratory and field were quite consistent from one tidal cycle to the next but there were considerable variations within single tidal cycles between different points within each station the data suggest that contraction within the elevational zone that is normally submerged twice a day by the tides is by alternate wetting and drying short term changes in elevation are generally low compared with annual rates of downwearing owing to erosion but they may generate stresses that contribute to rock breakdown copyright 2007 john wiley sons ltd

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

comparison between coastal and inland karst limestone lowering rates in the northeastern adriatic region italy and croatia a comparison among lowering rates collected in the limestones of the northeastern adriatic region italy and croatia gives a picture of the erosion patterns in the inland and coastal classical karst and istrian karst erosion rates were measured using either a micro erosion meter or a traversing micro erosion meter beginning from a large dataset spread over a maximum of 26 years significant differences in limestone lowering rates have been recognized in the surveyed area the mean lowering rate for the inland classical karst area is 0 018 mm yr whereas in the inland istrian karst it is 0 009 mm yr in the coastal sectors the mean erosion rate varies between 0 14 mm yr in the gulf of trieste and 0 04 mm yr in the sites located along the istrian shoreline these differences are probably due to the climatic setting of the classical karst area mediterranean continental to sub alpine climate and istrian peninsula mediterranean climate moreover along the coasts of the gulf of trieste there are many submarine springs which are absent along the istrian coast it is hypothesized that these underwater springs stress the effect of rainfall along the coast which is both direct rain on the measurement site and mainly indirect freshwater outflow from submarine springs higher lowering rates were surveyed during autumn rainfall therefore also freshwater outflow from submarine springs is particularly high at the end of the summer and in autumn

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

shore platform downwearing in eastern canada micro tidal gaspe quebec abstract work has been conducted in the laboratory and field on a micro tidal subhorizontal shore platform in argillaceous rocks at mont louis in gaspe quebec surface downwearing rates for 450 rock samples were measured over 3 years in the laboratory at the neap low mid and high tidal levels under semi diurnal tidal conditions de ionized water was used to determine the role of wetting and drying and artificial sea water for the additional effect of salt and possibly chemical weathering another 300 samples were immersed in de ionized water or artificial sea water for 90 min every 1 2 or 3 weeks representing conditions between the neap and spring high tidal levels and exposed in air for 90 min every 1 2 or 3 weeks to represent conditions between the neap and spring low tidal levels surface downwearing was recorded in the field at 34 transverse micro erosion meter tmem stations most of which were installed along 4 shore normal profiles in 2004 and 2005 mean downwearing rates in the laboratory ranged from 1 25 mm yr 1 at the neap high tidal level to 0 63 mm yr 1 at the neap low tidal level downwearing was much slower between the neap and spring tidal levels and it was uniformly slow below the neap low tidal level the presence of salts inhibited downwearing within the neap tidal range where wetting and drying was dominant and promoted it between the neap and spring high and low tidal levels surface swelling was fairly common in the field and the mean downwearing rate 0 242 mm yr 1 was much lower than in the laboratory possibly because the tmem stations were installed in harder rocks modeling supports the contention that the mont louis platform was cut initially by waves at a higher elevation and then lowered by weathering in the last few thousand years as relative sea level fell to its present elevation

forty three years of micro erosion meter monitoring of erosion rates on shore platforms at kaikōura peninsula south island new zealand abstract using micro erosion meters mem and traversing micro erosion meters tmem surface lowering rates of shore platforms on kaik ura peninsula south island new zealand have been measured over a total of 43 years this record is the longest monitored network of this type since 1973 erosion rates have been calculated over two two year periods 1973 1975 n 31 and 1993 1996 n 55 and at decadal scales 1973 1993 n 15 1973 2004 n 12 1993 2004 n 46 1993 2008 n 34 1993 2016 n 18 1973 2016 n 6 after 43 years surface lowering rates remain similar to previously published rates at an average of 0 525 to 1 181 mm a 1 statistical analysis shows that erosion rates over all measurement periods are derived from the same population thus short term rates derived from two years of monitoring remain indicative of decadal rates of erosion variations between measurement periods are best explained by the loss of the more rapidly eroding bolt sites these losses point to the difficulty of maintaining monitoring over longer time scales a means of statistical manipulation previously published allows for these losses to be accounted for in determining long term rates of platform lowering in november 2016 a mw 7 8 earthquake raised the kaik ura peninsula approximately 0 8 1 m elevating much of the shore platforms above the tide range this earthquake has reset the mem record ending this long running erosion monitoring site of shore platform surface lowering however the mem network is now being used to monitor post earthquake response of the uplift shore platforms and new marine terraces

morphometry and elevation of the last interglacial tidal notches in tectonically stable coasts of the mediterranean sea abstract we report detailed morphometric observations on several mis 5 5 and a few older mis 11 21 25 fossil tidal notches shaped along carbonate coasts at 80 sites in the central mediterranean sea and at an additional six sites in the eastern and western mediterranean at each site we performed precise measurements of the fossil tidal notch ftn width and depth and of the elevation of its base relative to the base of the present tidal notch ptn the age of the fossil notches is obtained by correlation with biologic material associated with the notches at or very close to the site this material was previously dated either through radiometric analysis or by its fossiliferous content the width i e the difference in elevation between base and top of the notches ranges from 1 20 to 0 38 m with a mean of 0 74 m although the ftn is always a few centimetres wider than the ptn probably because of the lack of the biological reef coupled with a small erosional enlargement in the ftn the broadly comparable width suggests that tide amplitude has not changed since mis 5 5 times this result can be extended to the mis 11 features because of a comparable notch width but not to the mis 21 and 25 epochs although observational control of these older notches is limited we regard this result as suggesting that changes in tide amplitude broadly occurred at the early middle pleistocene transition the investigated mis 5 5 notches are located in tectonically stable coasts compared to other sectors of the central mediterranean sea where they are uplifted or subsided to 100 m and over in these stable areas the elevation of the base of the mis 5 5 notch ranges from 2 09 to 12 48 m with a mean of 5 7 m such variability although limited indicates that small land movements deriving from slow crustal processes may have occurred in stable areas we defined a number of sectors characterized by different geologic histories where a careful evaluation of local vertical land motion allowed the selection of the best representative elevation of the mis 5 5 peak highstand for each sector this elevation has been compared against glacial isostatic adjustment gia predictions drawn from a suite of ice sheet models ice g5 ice g6 and anice selen that are used in combination with the same solid earth model and mantle viscosity parameters results indicate that the gia signal is not the main cause of the observed highstand variability and that other mechanisms are needed the gia simulations show that even within the mediterranean basin the maximum highstand is reached at different times according to the geographical location our work shows that besides gia even in areas considered tectonically stable additional vertical tectonic movements may occur with a magnitude that is significantly larger than the gia

erosion of rocky shore platforms by block detachment from layered stratigraphy the majority of shore platforms form in rocks that are characterised by layered stratigraphy and pervasive jointing plucking of weathered joint and bed bounded blocks is an important erosion process that existing models of platform development do not represent globally measuring platform erosion rates have focused on microscale 1 mm surface lowering rather than mesoscale 0 1 1 m block detachment yet the latter appears to dominate the morphological development of discontinuity rich platforms given the sporadic nature of block detachment on platforms observations of erosion from storm event to multi decadal timescales and beyond are required to quantify shore platform erosion rates to this end we collected aerial photography using an unmanned aerial vehicle to produce structure from motion derived digital elevation models and orthophotos these were combined with historical aerial photographs to characterise and quantify the erosion of two actively eroding stratigraphic layers on a shore platform in glamorgan south wales uk over 78 years we find that volumetric erosion rates vary over two orders of magnitude 0 1 10 m3 yr 1 and do not scale with the length of the record average rates over the full 78 year record are 2 5 m3 yr 1 these rates are equivalent to 1 2 5 3 mm yr 1 surface lowering rates an order of magnitude faster than previously published both at our site and around the world in similar rock types we show that meso scale platform erosion via block detachment processes is a dominant erosion process on shore platforms across seasonal to multi decadal timescales that have been hitherto under investigated

modelling the development of dynamic equilibrium on shore platforms abstract a numerical model was used to determine whether the landward migration of shore platforms at the low tidal level due to downwearing and possibly other mechanisms can match the recession caused by wave erosion at the high tidal level the hybrid model calculated the time required to undercut a cliff face and to remove the debris and the amount of recession accomplished at the low tidal level during that time these iterations were repeated over the equivalent of a 40 000 year period the rates of high tidal erosion calculated during model runs were representative of cliff recession rates recorded in the field and downwearing rates specified for each run were based on data recorded on shore platforms with micro erosion meters almost all runs demonstrated that platform gradients decline asymptotically to a state of dynamic equilibrium that is strongly related to tidal range and rock resistance although its relationship to wave height varies according to attenuation rates in the surf zone periodic changes in rock resistance and continuous changes in cliff height can introduce perturbations that delay equilibrium or depending on their severity prevent its occurrence the conclusion that platforms trend towards dynamic as opposed to static equilibrium is contrary to other models which have considered only the effect of wave erosion the results of this work have important implications for coastal modelling and the estimation of platform lowering for cosmogenic dating

the morphodynamics of shore platforms in a micro tidal setting interactions between waves and morphology abstract the interactions between waves and morphology on shore platforms were investigated at four platforms located at kaikoura peninsula new zealand and the otway coast victoria australia waves were measured over six tidal peaks of a spring tidal sequence at each site during a six month period february 2007 july 2007 this paper reports the results of an investigation into the research question how are waves modified by platform morphology in a micro tidal setting through the investigation of wave interactions on shore platforms it was found that complex hydrodynamic patterns formed on the shore platforms studied through direct measurement of waves on the platforms it was found that wave attenuation was not dependent on platform width but rather influenced by platform gradient and depth of water on the platform spectral analysis was used to assess how wave energy was transformed across the platforms at three of the four platforms investigated energy gradients formed across the platform with wave energy recorded within the infragravity range

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 300 to 550 year history of slip on the imperial fault near the u s mexico border missing slip at the imperial fault bottleneck subsurface investigation of the imperial fault zone approximately 50 60 m south of the u s mexico international border in mexicali valley reveals that only the 1940 imperial valley earthquake m l 7 1 has produced significant surface slip in the past 300 years the 1940 earthquake produced about 5 m of slip in this vicinity as indicated by an offset tree line we excavated a buried channel adjacent to these trees and determined that it is also offset 5 m these data indicate that at least the upper meter of sediments has only been displaced by the 1940 event one other slip event of undetermined magnitude is recorded within the lacustrine highstand deposits of the last lake about 300 years ago there is no evidence of earlier faulting events in sediments that possibly may correlate to the penultimate lake approximately 550 years b p below an unconformity 4000 year old deltaic deposits are intensely faulted by previous slip along the imperial fault these data suggest that the slip rate on the imperial fault for the past 300 550 years is only about 15 20 mm yr substantially less than that expected from geodetic measurements and regional structural models this in turn suggests that either slip is accommodated by other faults in the border region or that strain release on the imperial fault is characterized by episodic clustered behavior

where is the seaward edge a review and definition of shore platform morphology abstract shore platforms are erosional coastal landforms that have attracted scientific attention since the mid 19th century the defining element of a platform is width that is used in many calculations such as determining a platform s evolutionary state or inferring how wave energy is distributed along the shore although a critical variable there are no uniform criteria for defining the seaward edge quantification of platform width has been driven by site specific variables with the seaward edge defined on the basis of tides morphology biology processes and sediment coverage the lack of a uniform definition has meant that comparative studies are difficult and results are possibly spurious as widths derived from very different criteria can vary by an order of magnitude just on the basis of which criteria is used to determine its edge in this review a combination of morphologic and process elements is used to define the seaward edge of a shore platform the development of strict criteria is especially needed in an environment of rising sea levels if measurements of landscape change are to be made in addition the advent of seamless datasets that cross the land sea boundary means that the delineation of platform morphology is no longer limited by physical access this review concludes that the seaward edge of a shore platform will occur at or landward of wave base and should be defined as the point where active erosion of the bedrock ceases characterised by erosional features such as notches and block plucking scars or the deposition of sediment of such a thickness that the underlying bedrock is not exposed during storm events

the influence of rock resistance on coastal morphology around lord howe island southwest pacific an erratum has been published for this article in earth surface processes and landforms 27 7 2004 931 lord howe island in the northern tasman sea is a remnant of a much larger late miocene basaltic shield volcano much of the island s coastline is exposed to waves that have unlimited fetch but a marked contrast is provided by a fringing coral reef and lagoon that very effectively attenuate wave energy along a portion of the western coastline the geology of the island is varied with hard and resistant basalt lavas breccias and tuffs of intermediate resistance and highly erodible eolianites this variability provides an excellent opportunity to examine the in uence of rock resistance on the development of the spectacular rock coast landforms that occur around the island the hardness of rocks and the extent of weathering around the coastline were assessed using a schmidt hammer and statistical analysis was undertaken to remove outlying values on all but one occasion higher mean rebound values were returned from fresh surfaces than weathered surfaces but only half of these differences were statistically signi cant shore platforms with two distinct levels are juxtaposed along two stretches of coastline and schmidt hammer results lend support to hypotheses that the raised surfaces may be inherited features relative rock resistance was assessed through a combination of schmidt hammer data and measurements of joint density and constrained on the basis of morphological data this approach formed a basis for examining threshold conditions for sea cliff erosion at lord howe island in the context of the distribution of resistant plunging cliffs and erosional shore platforms copyright 2004 john wiley sons ltd

modelling the quaternary evolution of shore platforms and erosional continental shelves a mathematical model was used to investigate the effect of glacially induced fluctuations in sea level on the evolution of wave cut shore platforms and erosional continental shelves during the quaternary the model used two deep water wave sets which were used to calculate breaker height and depth and the force of the waves at the waterline according to the width and bottom roughness of the surf zone and the gradient of the submarine slope the model also incorporated an erosional threshold related to the strength of the rocks the number of hours each year in which the water level is at each intertidal elevation and the amount and persistence of the debris at the cliff foot most runs were made using a sea level model that consisted of 26 glacial cycles from 2 million to 0 9 million years ago and nine of approximately twice the amplitude and wavelength in the last 0 9 million years the model emphasized the dynamic association between the contemporary intertidal platform and the continental shelf both surfaces trend towards a state of static equilibrium under oscillating sea level conditions when attenuated waves are unable to continue eroding the rock if there has not been enough time to reduce the gradient of the shallower portions of the continental shelf however intertidal shore platforms can be in a temporary though possibly long lasting state of dynamic equilibrium the model suggests that most platforms are at least in part inherited from one or in many cases more interglacial stages when sea level was similar to today s copyright 2001 john wiley sons ltd

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

tidal wetting and drying on shore platforms an experimental assessment abstract rocks were subjected to wetting and drying cycles with de ionized water under real time conditions using tidal simulators one third of the samples experienced 11 h of exposure and 1 h of inundation over a 12 h tidal cycle representing high tidal conditions one third experienced 6 h of exposure and 6 h of inundation representing mid tidal conditions and one third experienced 1 h of exposure and 11 h of inundation representing low tidal conditions we obtained 324 cores from igneous metamorphic and sedimentary rocks from ontario which were exposed to more than 930 wetting and drying cycles over 16 months we obtained 675 cores and cubes from basalts sandstones and argillites from shore platforms in eastern canada which were exposed to about 700 cycles over 12 months many of the cores and cubes experienced very little to no breakdown particularly those from the igneous and metamorphic rocks of ontario sandstones from a sloping platform in the macrotidal bay of fundy and argillites from a horizontal mesotidal platform in gaspe quebec were the most susceptible rock types with equivalent surface downwearing rates ranging from 0 to 4 mm year 1 the results suggest that downwearing rates decrease with elevation within the intertidal zone probably because rocks require much longer to desorb than to absorb water the experiments demonstrated that wetting and drying can be an important process on shore platforms in some types of rock helping to lower the height and reduce the gradient of sloping macrotidal platforms and to reduce the height of horizontal micro and mesotidal platforms

measuring erosion rates using the micro erosion meter 20 years of data from shore platforms kaikoura peninsula south island new zealand abstract fifteen micro erosion meter sites giving 42 individual readings of erosion were remeasured twenty years after installation on mudstone and limestone shore platforms on the kaikoura peninsula south island new zealand the mean annual surface lowering rate was calculated to be 1 43 mm yr longer term data were compared to shorter term data collected over a two year period between 1973 and 1975 to test the validity of extrapolating average erosion rates from shorter term data it was found that the average lowering rate for the shorter term data were in statistically acceptable agreement with those for the longer term data extrapolation of short term micro erosion meter data is therefore acceptable in this particular environment in previous work it has been suggested that measurements from as few as thirty individual micro erosion meter positions are required to calculate a mean annual lowering rate on shore platforms measurements from 30 mem positions provided an statistically acceptable mean annual lowering rate for shore platforms on the kaikoura peninsula

the formation of beaches on shore platforms in microtidal environments beaches are common features of many rocky shorelines and can be considered to be constrained by the underlying geology in mesotidal to macrotidal areas the slope of the substrate and sediment supply are the primary factors in constraining the size and development of beaches on shore platforms in microtidal settings it is not known if these factors are wholly responsible for determining the presence of beaches on shore platforms nor the contribution of other factors such as hydrodynamics the microtidal coast of victoria australia is surveyed in this study in order to quantify the morphological boundary conditions that constrain beach development on semi horizontal shore platforms an ample sediment supply indicates that the underlying geology is controlling the presence and absence of beaches where beaches occur they always overlie a rock ramp which is the steepest part of the platform the two most important morphological constraints were platform width and height both of which significantly correlated with beach volume an elevational threshold exists at just over 1 0 m where beaches cannot accumulate below this threshold platform width appears to be the principle constraining factor in beach accumulation an evolutionary model is inferred which suggests that dissipation of wave energy associated with platform widening plays an important role in allowing beaches to accumulate the model suggests beaches on platforms will be particularly sensitive to sea level rise copyright 2014 john wiley sons ltd

patterns of surface downwearing on shore platforms in eastern canada downwearing rates were measured on shore platforms at about 200 transverse micro erosion meter tmem stations over periods ranging from 2 to 6 years there were seven study areas in eastern canada the platforms were surveyed and a schmidt rock test hammer was used to measure rock hardness more than 1200 rock samples from three of the study areas were also subjected each day over a 3 year period to two tidal cycles of immersion and exposure which simulated the central intertidal zone a further 840 samples were subjected to longer periods of exposure and immersion over a 1 year period which represented different elevations within the upper and lower intertidal zone respectively these experiments suggested that tidally generated weathering and debris removal is an effective erosional mechanism particularly at the elevation of the lowest high tides in the field mean rates of downwearing for each study area ranged from 0 24 mm yr 1 to more than 1 5 mm yr 1 rates tended to increase with elevation in the field with maxima in the upper intertidal zone this trend in the field cannot be attributed entirely to the tidally induced weathering processes that were simulated in the laboratory and must reflect in part the effect of waves frost ice and other mechanisms it is concluded that there are no strong spatial downwearing patterns on shore platforms and that downwearing rates in the intertidal zone are the result of a number of erosional mechanisms with different elevation efficacy characteristics furthermore even if only one or two mechanisms were dominant in an area any resulting relationship between downwearing rates and elevation would be obscured or eliminated by the effect of variations in the chemical and physical characteristics of the rocks copyright 2010 john wiley sons ltd

rocky coasts their role as depositional environments abstract the role of rocky coasts as depositional environments has been generally neglected by rock and depositional coast workers although rock coasts can be hostile sedimentary environments they frequently host a variety of deposits consisting of mixes of boulders and megaclasts to sand and cobbles these deposits include pockets of sand and pebble trapped in topographic depressions or at the foot of scarps and cliffs isolated boulders pocket beaches trapped between headlands and sand to boulder beaches in shallow bays exposed to strong wave action the tectonic setting which is reflected in the degree of geological heterogeneity alongshore together with the wave regime and other elements of the morphogenic environment help to determine the amount and mobility of the sediment and consequently whether it plays an essentially abrasional or protectional role many beaches have a resistant rock foundation which will modulate their response to rising sea level and possibly increased storminess during this century wave refraction and temporal and spatial changes in sediment abrasional and protectional efficacy influence the development of crenulated planforms on coasts with a high degree of geological heterogeneity and possibly on more geologically homogeneous coasts with longshore variations in cliff height or in the amount of sediment theory suggests that these coasts may develop equilibrium planforms with uniform rates of erosion in bays and on headlands or they may undergo a series of cyclical transformations involving alternating increases and decreases in the depth of the bays relative to the headlands