the impact of rapid coastline changes and sea level rise on the tides in the bohai sea china 1 the tidal regime in the bohai sea china is investigated using observations and an established numerical tidal model the area has recently experienced rapid coastline changes due to natural developments of the yellow river delta and large scale anthropogenic land reclamation these morphological changes are not reflected in most global bathymetric databases and are thus rarely incorporated into investigations of the bohai sea it is shown that there have indeed been significant changes in the tidal regime in the bohai sea over the last 35 years with m2 amplitudes changing up to 20 cm in some parts the model captures some of these changes when the appropriate bathymetries are used furthermore the simulations show that the tides in the bohai sea have become more sensitive to future sea level rise and the way in which it is implemented in the model i e whether or not flood defenses are included these sensitivity changes are due to the recent coastal developments

on the factors behind large labrador sea tides during the last glacial cycle and the potential implications for heinrich events 1 labrador sea ls tidal elevations over the last glacial cycle are investigated in a near global numerical model that accurately captures the present day tides from 65 ka to 7 ka the modeled elevations at the debouchement point of the hudson strait ice stream in the ls are exceptionally large comparable to the largest elevations seen anywhere in the present day ocean new numerical simulations performed for this article demonstrate that both local changes in basin geometry e g ice cover over hudson bay and changes outside of the ls led to enhanced ls paleotides new simulations run at higher horizontal resolution and a considered examination of uncertainties including uncertainties in the adopted sea level models strengthen confidence in the robustness of the large ls paleotides the tide model is run with both spatially uniform sea level drops taken from curves of eustatic and red sea sea levels versus time and spatially variable sea level maps taken from two different gravitationally self consistent viscoelastic solid earth sea level models which both account for ice sheet geometry the tides are larger when the spatially variable sea level models are used observations in present day antarctica indicate that the mechanical action of tides significantly impacts the dynamics of both continental ice streams and their associated floating ice shelves it is postulated here that large ls paleotides played a key role in the formation of heinrich event icebergs that is massive discharges of ice from the ls into the glacial north atlantic ocean the paleotide calculations described here provide a potential explanation for why the ls region more than any other dominated the production of heinrich event icebergs most previous hypotheses of a tidal role in climate variability and ice sheet dynamics focus on tidal mixing in contrast here the role of tidal mechanical forcing of ice sheets is emphasized

rock coast inheritance an example from galicia northwestern spain a shore platform on the western coast of galicia in northwestern spain has been inherited from interglacial stages when sea level was similar to today the wide gently sloping intertidal platform is backed in places by supratidal rock ledges and in other places by a steeper and narrower supratidal ramp the gradient of the intertidal platform is consistent with the relationship between platform gradient and tidal range but the slope of the ramp is much too high the abandoned and degraded sea cliff is grass covered along most of this coast and the ledges and the ramp which extend up to several metres above the highest tides are covered by lichen and in places by salt tolerant plants radiocarbon dated sediments in the cliff which range up to 36 000 years in age lie on top of an ancient beach deposit the former beach remnants of which are found in situ on the ramp and rock ledges as well as two caves that are filled with the dated sediments are probably last interglacial in age the morphological and sedimentary evidence suggests that the supratidal ramp and ledges were also formed during the last interglacial stage whereas the wider intertidal platform is probably the product of several older interglacials when sea level was generally similar to today a general model is proposed for the inheritance of shore platforms in macro and microtidal environments copyright 1999 john wiley sons ltd

can we model the effect of observed sea level rise on tides the link between secular changes in the lunar semidiurnal ocean tide m 2 and relative sea level rise is examined based on numerical tidal modeling and the analysis of long term sea level records from europe australia and the north american atlantic coasts the study sets itself apart from previous work by using a 1 12 global tide model that incorporates the effects of self attraction and loading through time step wise spherical harmonic transforms instead of iteration this novel self attraction and loading implementation incurs moderate computational overheads some 50 and facilitates the simulation of shelf sea tides with a global root mean square error of 14 6 cm in depths shallower than 1 000 m to reproduce measured tidal changes in recent decades the model is perturbed with realistic water depth changes compiled from maps of altimetric sea level trends and postglacial crustal rebound the m 2 response to the adopted sea level rise scenarios exhibits peak sensitivities in the north atlantic and many marginal seas with relative magnitudes of 1 5 per century comparisons with a collection of 45 tide gauge records reveals that the model reproduces the sign of the observed amplitude trends in 80 of the cases and captures considerable fractions of the absolute m 2 variability specifically for stations in the gulf of mexico and the chesapeake delaware bay system while measured to model disparities remain large in several key locations such as the european shelf the study is deemed a major step toward credible predictions of secular changes in the main components of the ocean tide

an exploratory numerical model of rocky shore profile evolution abstract rocky shores occur along much of the world s coastline and include a wide range of coastal morphologies such as intertidal shore platforms considerable research effort has been placed on trying to understand developmental processes on rocky shores but progress has been forestalled because these landscapes develop slowly and preserve little evidence of evolution through time this paper presents a new exploratory numerical model developed to study long term shore profile evolution on rock coasts the model purposely considers only a limited number of processes each represented in a highly abstracted way despite these simplifications the model exhibits a large range of emergent shore profile shapes this behavior is enabled both by broader spatial representation of the driving erosion forces and the flexibility provided by a grid discretization scheme initial model testing shows the development of varied rocky profile geometries ranging from steep plunging cliffs cliffs with narrow benches and cliffs with a variety of shore platform shapes most of the model geometries are similar to those observed in the field and model behavior is robust and internally consistent across a relatively large parameter space this paper provides a detailed description of the new model and its subsequent testing emphasis is placed on comparison of model results with published field observations in which morphometric relationships are described between shore platform gradient and tidal range and platform elevation and platform width the model adequately simulates these morphometric relationships while retaining its ability to simulate a wide range of profile shapes the simplicity of process representations and the limited number of processes implemented means that model outputs can be interpreted reasonably easily hence an opportunity is now provided following the testing described in this paper to use the model to systematically investigate the broader controlling conditions on rock shore profile development

chalk coast dynamics implications for understanding rock coast evolution rock cliffs and shore platforms are linked components of the world s coastal zone understanding of the dynamics of their relationships has been hindered by the often imperceptible changes that occur within human time scales the cretaceous chalk coasts of northwest europe and particularly those of southeast england are among the most dynamic and most intensively studied cliffed rock coasts in the world perceptible changes to both cliffs and platforms have been measured on monthly seasonal annual and decadal time scales through a review of previously published data and the addition of data not previously published average cliff retreat rates are calculated as 0 49 0 38 m y 1 and platform erosion rates 3 999 3 208 mm y 1 this paper highlights some of the interactions over time and space between process and measurement that continue to limit our understanding of the dynamics of rock coasts in particular the link between rates of cliff retreat and platform erosion it concludes by identifying fruitful areas for future research keywords rock coast cliff shore platform chalk coastal erosion weathering

a lateglacial age for the main rock platform western scotland the sea level record preserved in ancient shorelines forms a basis for studies of tectonic uplift glacial loading and the changing volume of the oceans the existing record is derived largely from depositional features such as beach ridges and coral reefs which contain material suitable for radiometric dating erosional shorelines have proved more difficult to date direct age estimates for shore platforms can now be obtained with exposure dating techniques based on cosmic ray produced isotopes here we report measurements of cosmogenic 36 cl on the main rock platform in western scotland that indicate its formation in a postglacial event spanning less than a few thousand years together with isostatic modeling the 36 cl results suggest cutting during the younger dryas in britain the lateglacial or loch lomond stadial when stable sea level and severe climatic conditions combined to enhance bedrock erosion

modeling the role of weathering in shore platform development a mathematical wave erosional model was modified to study the additional effect of weathering by wetting and drying and salt weathering on the development of shore platforms in macro to mesotidal environments model rates of downwearing by these processes at different tidal elevations were based on data obtained from a series of laboratory experiments on sandstones from eastern canada backwearing by mechanical wave erosion was calculated using basic wave equations there were several types of run which were designed to determine the effect of weathering and the production of fine grained sediment the periodic accumulation of debris on weathering in the upper intertidal zone and weathering in reducing rock resistance and facilitating wave quarrying the results implied that compared to mechanical wave erosion the direct effect of weathering and fine grained sediment production makes only a small contribution to the long term development of shore platforms the relationship between cliff foot debris occurrence and platform development and morphology was inconsistent because of the negative feedback relationship between erosion rates surface gradients and rates of wave attenuation the model suggested that weathering can play an important indirect role in assisting wave quarrying of joint blocks and other rock fragments

millennial scale stratigraphy of a tide dominated incised valley during the last 14 kyr spatial and quantitative reconstruction in the tokyo lowland central japan spatial and quantitative analysis of infilling processes of the tide dominated incised valleys beneath the tokyo lowland during the last 14 kyr was undertaken by using data from 18 sediment cores 467 radiocarbon dates and 6100 borehole logs the post last glacial maximum valley fills consist of braided river meandering river estuary spit and delta systems in ascending order the boundary between the estuary and delta systems is regarded as the maximum flooding surface the maximum flooding surface beneath the tokyo lowland is dated at 8 ka in the arakawa valley and 7 ka in the nakagawa valley this age difference is due to the migration of the tone river from the arakawa valley to the nakagawa valley at 5 ka and suggests that the widely held view that the global initiation of deltas coincided with the abrupt rise of sea level at 9 to 8 ka is true only where there has been steady sediment supply from major rivers the meandering river system is dominated by sheet like sands that were deposited during lateral migration of channels during the younger dryas and isolated vertical sands within muds that reflect vertical aggradation of channels before and after the younger dryas the transition between these channel geometries is controlled by a threshold sea level rise of 4 to 7 mm yr 1 before migration of the tone river at 5 ka the tide dominated bay in the nakagawa valley was filled by upward fining laterally accreting muds the muds accreted from the margin to the axis of the bay such lateral accretion of suspended particles derived from outside the bay has been documented in other tide dominated coastal environments and is probably common in other similar settings after the migration of the tone river the bay was filled by upward coarsening deltaic sediments

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

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

hydrodynamic constraints and storm wave characteristics on a sub horizontal shore platform few studies of wave processes on shore platforms have addressed the hydrodynamic thresholds that control wave transformation and energy dissipation especially under storm conditions we present results of a field experiment conducted during a storm on a sub horizontal shore platform on the east coast of auckland new zealand small 2 5 times the gravity wave height 0 05 0 33 hz is necessary for waves to propagate onto the platform without breaking on the platform surface the wave height is a direct function of water depth with limiting maximum wave height to water depth ratios of 0 55 and 0 78 at the centre of the platform and cliff toe respectively a relative platform edge submergence water depth water height ratio threshold of 1 1 is identified below which infragravity 0 05 hz wave energy dominates the platform energy spectra and above which gravity waves are dominant infragravity wave height transformation across the platform is governed by the relative platform edge submergence finally the paper describes the first observations of wave setup on a shore platform during the peak of the storm wave setup on the platform at low tide 0 21 m is consistent with measurements from planar sandy beaches but at higher tidal stages the ratio between incident wave height and maximum setup was lower than expected copyright 2014 john wiley sons ltd

modeling the development of wave cut shore platforms abstract a mathematical model was used to investigate the development of wave cut shore platforms with constant sea level the model considered the effects of deep water wave height spectra period and wavelength breaker height and depth breaker type the width and bottom roughness of the surf zone the gradient of the submarine slope 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 intertidal erosion rates were calculated according to the force of the surf reaching the shoreline whereas submarine erosion rates were determined using a depth decay variable each of the two hundred and fifty model runs consisted of 300 000 iterations platform width increased and gradient progressively decreased through model runs and states of static equilibrium were attained by the end of one hundred and nine runs when the wave induced force at each point in the intertidal zone had became too weak to continue eroding the rock runs with mesotidal spring tidal range 3 m generally produced subhorizontal platforms with cliff platform junctions at the mean low water neap tidal level a greater variety of profiles was produced in runs with macrotidal spring tidal ranges 9 m although almost 30 of these runs produced gently sloping platforms with average gradients of only 0 3 about two thirds of the simulated profiles had average gradients ranging from about 1 to 3 simulated platform width increased with tidal range and decreased with the rate of submarine erosion rock resistance the roughness or irregularity of the platform surface the amount and persistence of the cliff foot debris and wave period because higher waves break in deeper water than lower waves there was no consistent relationship between simulated platform width and wave height

numerical modeling of the global semidiurnal tide in the present day and in the last glacial maximum 1 a hydrodynamic model incorporating a self consistent treatment of ocean self attraction and loading sal and a physically based parameterization of internal tide it drag is used to assess how accurately barotropic tides can be modeled without benefit of data and to explore tidal energetics in the last glacial maximum lgm m2 solutions computed at high resolution with present day bathymetry agree with estimates of elevations from satellite altimetry within 5 cm rms in the open ocean this accuracy and agreement with atlimetric estimates of energy dissipation are achieved only when sal and it drag are included in the model solutions are sensitive to perturbations to bathymetry and inaccuracies in available global databases probably account for much of the remaining error in modeled elevations the 100 m drop in sea level during the lgm results in significant changes in modeled m2 tides with some amplitudes in the north atlantic increasing by factors of 2 or more dissipation is also significantly changed by the drop in sea level if it drag estimated for the modern ocean is assumed dissipation increases by about 50 globally and almost triples in the deep ocean however it drag depends on ocean stratification which is poorly known for the lgm tests with modified it drag suggest that the tendency to a global increase in dissipation is a robust result but details are sensitive to stratification significant uncertainties about paleotides thus remain even in this comparatively simple case where bathymetry is well constrained

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

sensitivity of palaeotidal models of the northwest european shelf seas to glacial isostatic adjustment since the last glacial maximum abstract the spatial and temporal distribution of relative sea level change over the northwest european shelf seas has varied considerably since the last glacial maximum due to eustatic sea level rise and a complex isostatic response to deglaciation of both near and far field ice sheets because of the complex pattern of relative sea level changes the region is an ideal focus for modelling the impact of significant sea level change on shelf sea tidal dynamics changes in tidal dynamics influence tidal range the location of tidal mixing fronts dissipation of tidal energy shelf sea biogeochemistry and sediment transport pathways significant advancements in glacial isostatic adjustment gia modelling of the region have been made in recent years and earlier palaeotidal models of the northwest european shelf seas were developed using output from less well constrained gia models as input to generate palaeobathymetric grids we use the most up to date and well constrained gia model for the region as palaeotopographic input for a new high resolution three dimensional tidal model roms of the northwest european shelf seas with focus on model output for 1 ka time slices from the last glacial maximum taken as being 21 ka bp to present day we demonstrate that spatial and temporal changes in simulated tidal dynamics are very sensitive to relative sea level distribution the new high resolution palaeotidal model is considered a significant improvement on previous depth averaged palaeotidal models in particular where the outputs are to be used in sediment transport studies where consideration of the near bed stress is critical and for constraining sea level index points

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

tectonic inversion in the santa barbara system of the central andean foreland thrust belt northwestern argentina 1 the santa barbara system sbs of northern argentina is a 400 km long segment of the subandean foreland thrust belt it is characterized by predominantly west verging relatively high angle thrust faults many of these faults are reactivated normal faults from one branch of a complex cretaceous to paleogene rift system heteroaxial folding in parts of the sbs is probably due to a slight component of range parallel dextral strike slip motion acting on preexisting faults striking north and ne during inversion regional balanced cross sections along two transects across the northern sbs indicate that the major faults flatten into a detachment in the basement at about 10 km depth neogene e w contraction in the sbs is of the order of 21 26 km rift extension is not very well constrained but was probably less than 10 km the structural style of the sbs differs from the thin skinned subandean thrust belt to the north and from the large wavelength sierras pampeanas basement uplifts to the south the changes between the different styles are sharp and coincide with the northern and southern boundaries of the rift in the foreland suggesting that crustal or lithospheric heterogeneities exert an overriding control on foreland structural style

vertical tectonic crustal movements along the japanese coastlines inferred from late quaternary and recent relative sea level changes abstract observed relative sea level rsl changes during the past 130 kyr make it possible to evaluate the vertical crustal movement due to several tectonic processes such as the subduction of oceanic plates here we infer average rates of tectonic crustal movement along the japanese coastlines on three typical timescales of 50 yr 6 kyr and 125 kyr based on tide gauge and holocene rsl observations and the altitudes of marine terraces formed at the last interglacial lig phase at 125 ka the rates on a timescale of 50 yr are derived from tide gauge data thermosteric sea level changes due to thermal expansion of the oceans and predictions due to the glacio hydro isostatic adjustment gia for the last deglaciation and also recent melting of the mountain glaciers and greenland and antarctic ice sheets those for 6 kyr and 125 kyr are based on the rsl observations and the predictions by gia modelling considering uncertainties for temporal changes in eustatic sea level for the mid to late holocene and lig phase the inferred rates for 50 yr are significantly different from those for 125 kyr in most sites particularly for sites along the coastline from eastern hokkaido to northeastern japan shikoku and south kyushu facing the pacific ocean in these regions the rates for 125 kyr and 50 yr are positive uplift and negative subsidence respectively also the observed rsl changes at 6 ka are consistent with the inferred rsl changes using the rates for 125 kyr and gia predictions in many sites but inconsistent with those for 50 yr in most sites except for a few sites these results suggest that the rates on a timescale of 50 yr are not representative of the tectonic crustal movements for timescales longer than 6 kyr in most sites along the japanese coastlines however the inferred rates on these timescales may be useful in discussing the recurrence of megathrust earthquake with its interval of 1 kyr such as the 2011 earthquake off the pacific coast of tohoku

towards an improved understanding of erosion rates and tidal notch development on limestone coasts in the tropics 10 years of micro erosion meter measurements phang nga bay thailand knowledge and understanding of shore platform erosion and tidal notch development in the tropics and subtropics relies mainly on short term studies conducted on recently deposited carbonate rocks predominantly holocene and quaternary reef limestones and aeolianites this paper presents erosion rates measured over a 10 year period on notches and platforms developed on the permian ratburi limestone at phang nga bay thailand in so doing it contributes to informing a particular knowledge gap in our understanding of the erosion dynamics of shore platform and tidal notch development in the tropics and subtropics notch erosion rates on relatively hard ancient limestones measured directly on the rock surface using a micro erosion meter mem over time periods of a decade or more the average intertidal erosion rate of 0 231 mm yr is lower than erosion rates measured over 2 3 years on recent weaker carbonate rocks average erosion rates at phang nga vary according to location and site and are in rank order from highest to lowest mid platform 0 324 mm yr notch floor 0 289 mm yr rear notch wall 0 228 mm yr lower platform 0 140 mm yr notch roof 0 107 mm yr and supratidal 0 095 mm yr the micro relief of the eroding rock surfaces in each of these positions exhibits marked differences that are seemingly associated with differences in dominant physical and bio erosion processes the results begin to help inform knowledge of longer term shore platform erosion dynamics models of marine notch development and have implications for the use of marine notches as indicators of changes in sea level and the duration of past sea levels copyright 2014 john wiley sons ltd

tidal evolution of the northwest european shelf seas from the last glacial maximum to the present 1 two dimensional paleotidal simulations have been undertaken to investigate tidal and tide dependent changes tidal amplitudes tidal current velocities seasonal stratification peak bed stress vectors that have occurred in the nw european shelf seas during the last 20 ka the simulations test the effect of shelf wide isostatic changes of sea level by incorporating results from two different crustal rebound models and the effect of the ocean tide variability by setting open boundary values either fixed to the present state or variable according to the results of a global paleotidal model the use of the different crustal rebound models does not affect the overall changes in tidal patterns but the timing of the changes is sensitive to the local isostatic effects that differ between the models the incorporation of ocean tide changes greatly augments the amplitude of tides and tidal currents in the celtic and malin seas before 10 ka bp and has a large impact on the distribution of seasonally stratified conditions magnitude of peak bed stress vectors and tidal dissipation in the shelf seas the predictions on seasonal stratification are supported by well dated evidence on tidal mixing front migration in the celtic sea additional experiments using the global model suggest that the variability of offshore tides has been caused mainly by changes of eustatic sea level and ice sheet extent in particular a large decrease observed at 10 8 ka bp is attributed to the opening of hudson strait accompanied by the retreat of the laurentide ice sheet

storm wave currents boulder movement and shore platform development a case study from east lothian scotland article i nfo understanding the distribution of wave energy on shore platforms is important for models of the long term development of both shore platforms and backing cliffs little is known however of the magnitude of the wave currents generated on shore platforms in storms this study uses the distribution of boulders of different sizes on a shore platform on the north sea coast of scotland to investigate patterns of storm wave current velocities in storms over the last 40 240 yr blocks as large as 9 m 3

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

along strike structural variations in the southern patagonian andes insights from physical modeling abstract the southern patagonian andes between 48 and 53 sl offers a unique opportunity to study the results of orogenic growth superimposed over a previously rifted region in this sector the northern austral or magallanes basin was affected by late to middle jurassic extension followed by late cretaceous to neogene tectonic compression the resultant fold thrust belt displays significant along strike variations in width and lateral position of the structural domains that may be reflecting a first order control of the jurassic extensional depocenters as proposed in previous works this hypothesis is tested using a series of scaled sandbox analog models involving the positive inversion of two adjacent depocenters with different extensional rates accommodated by a transfer fault the correlation between structures in the southern patagonian andes and the features in the model have important first order similarities supporting the theory of a positively inverted extensional basin with a previous history of southward increase in extension moreover structural cross sections analyzed from field and seismic data have a geometry that is consistent with serial cross sections resulting from the models

upper quaternary marine terrace chronology and deformation south taranaki new zealand an extensive flight of late quaternary marine terraces in the south taranaki region of the north island of new zealand is dated using fission track radiocarbon and amino acid racemization methods a simple model of terrace deformation based on a doming type uplift pattern allows terrace strandline ages to be estimated twelve strandlines are recognized and are estimated to have formed during high sea level stands at 60 000 80 000 100 000 120 000 135 000 210 000 310 000 340 000 400 000 450 000 520 000 600 000 and 680 000 yr b p

tidal mixing and the meridional overturning circulation from the last glacial maximum 1 using a global tidal model it is shown that the supply of tidal energy to the deep ocean was larger during the last glacial maximum lgm 18 000 22 000 years bp the results were used to modify the rate of vertical mixing in a coupled ocean atmosphere model set up for the present and lgm oceans the increased levels of mechanical energy during the lgm were countered by a fresher upper north atlantic which led to a reduced circulation and deep water formation in spite of a trebling of the implicit mixing energy this identifies the significance of accurately representing vertical mixing in climate models to estimate the recovery time scales and timings of rapid catastrophic paleoceanographic events from the estimated levels of implicit energy in the vertical mixing scheme an amendment to diffusivity based mixing schemes is suggested

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

tides and tidal torques of the world ocean since the last glacial maximum peltier s 1994 paleobathymetries are used to investigate tides and corresponding balances of torques of the world ocean since the last glacial maximum 21 000 years before present simulations with a numerical tidal model point out that variable ice loads at the earth s surface and rearrangements in the interior led to considerable modifications of the resonance behavior of the oceans associated evident changes of the tidal range were not confined to the vicinity of formerly ice covered areas in contrast to the tidal oscillation system that was subject to almost uniform changes since the beginning of ice retreat the dissipation rate of the m2 tide increased distinctly during the principal melting time from 15 to 8 kyr b p and reached a local extreme eight thousand years ago though surface and volume of the world ocean were already very similar to present conditions postglacial deformations during the following two thousand years caused the decrease of tidal dissipation from the maximum value to the present day level indicating the sensibility of tidal torques and dissipation rates to comparatively small variations of ocean s geometry since the vicinity of the tidal oscillation system to a resonance situation is more decisive with respect to total dissipation than the extension of shelves where most of the tidal dissipation is expected to take place states of extreme dissipation rates do not necessarily coincide with extreme bathymetric conditions

modelling the effect of waves weathering and beach development on shore platform development a mathematical model was used to study shore platform development mechanical wave erosion was dependent on such variables as tidal range wave height and period breaker height and depth breaker type surf zone width and bottom roughness submarine gradient rock resistance and the elevational frequency of wave action within the intertidal zone also included were the effects of sand and pebble accumulation cliff height and debris mobility and downwearing associated with tidal wetting and drying the occurrence location and thickness of beaches often depended on initially quite minor variations in platform morphology but owing to their abrasive or protective effect on underlying rock surfaces they were able to produce marked differences in platform morphology generalizations are difficult but the model suggests that platform gradient increases with tidal range platform width also increases with tidal range with slow downwearing but it decreases with fast downwearing platform gradient decreases and width increases with wave energy and decreasing rock resistance and platform roughness with low tidal range platform gradient is generally lower and platform width greater with beaches of fine sand than with gravel but the relationship is more variable with a high tidal range platform width increases and platform gradient decreases with the rate of downwearing on bare surfaces particularly in low tidal range environments but the pattern is less clear on beach covered platforms platforms with large amounts of beach sediment tend to be narrower and steeper than bare platform surfaces platform gradient increases and platform width decreases with increasing cliff height and with decreasing cliff debris mobility copyright 2005 john wiley sons ltd

difference in timing of maximum flooding in two adjacent lowlands in the tokyo area caused by the difference in sediment supply rate abstract the arakawa incised valley fill beneath the tokyo area japan has formed by delta progradation during holocene transgression and highstand this paper presents the integrated stratigraphy of this valley fill as deduced from three continuous sediment cores with rich radiocarbon age control and abundant data from the surrounding and compares the filling history with the adjacent nakagawa valley six depositional units make up the valley fill distinguished based on sedimentary facies in a sequence stratigraphic framework these units span from lowstand fluvial deposits latest pleistocene through retrogradational to transgressive marine deposits early and middle holocene to highstand fluvio deltaic deposits middle and late holocene the isochron and stacking pattern of sedimentary facies indicate that around 8 cal ka bp the shoreline trajectory flipped from landwards to seawards and maximum flooding occurred in the arakawa valley this is considerably earlier than in the neighboring nakagawa valley where this happened between 7 and 6 cal ka bp differences in the sediment supply at the time of transgression explain the diachronicity the findings identify the tone river which was at that time feeding the arakawa valley as a system of very large sediment supply compared to average rivers worldwide

high resolution numerical modeling of tides in the western atlantic gulf of mexico and caribbean sea during the holocene 1 tidal constituents and datums are computed on a high resolution grid of the northwestern atlantic ocean including the gulf of mexico and the caribbean sea a global model is used to determine tidal parameters on a grid with a nominal resolution of 800 800 the global model includes self attraction and loading drag in shallow marginal seas and internal tide drag in the deep ocean simulations are performed at 1000 year intervals during the holocene 10 000 calibrated years before present 10 ka in combination with changes in bathymetry and coastline location derived from a glacial isostatic adjustment model the global model results are then used to force a regional barotropic tidal model the regional model uses an unstructured finite element grid with very high resolution at the coastline the model results reveal significant variations in tidal constituent amplitudes throughout the holocene in the northwestern atlantic semi diurnal components show a strong amplification at around 9 ka while in the gulf of mexico the response is much more muted variations in diurnal tidal parameters are found to be less significant than semi diurnal parameters throughout the model domain changes in tidal range of great relevance to changes in relative sea level rsl are also investigated throughout the holocene the overall structure is similar to the patterns observed in the m2 tide with peak increases of 200 300 relative to present day being observed along the east coast of the united states from 9 to 8 ka finally the high spatial resolution of the regional model allows for the investigation of tidal changes at spatial scales e g individual bays much smaller than in previous studies

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

an early holocene sea level jump and delta initiation 1 early holocene sea level change controlled the evolution of clastic coastal depositional systems radiocarbon dated borehole cores obtained from three incised valley fill systems in asia changjiang song hong and kiso river record very similar depositional histories especially between about 9000 and 8500 cal bp sedimentary facies changes from estuarine sand and mud to shelf or prodelta mud suggest that the marine influence in the incised valleys increased during this period in addition large decreases in sediment accumulation rates occurred a sea level jump causes an estuarine system and its depocenter to move rapidly landward it is possible that the final collapse of the laurentide ice sheet accompanied by catastrophic drainage of glacial lakes at approximately 8500 cal bp caused such a jump the jump was followed immediately by a period of decelerated sea level rise that promoted delta initiation

methods for measuring rock surface weathering and erosion a critical review studies of rates processes and modes of rock surface and near surface deterioration and also hardening are central to rock weathering and building stone research conservation and management there is a need to measure and monitor weathering at the rock atmosphere interface to facilitate understanding of climatic environmental and lithological controls on the evolution and development of surface weathering features this paper reviews long established and recently developed field and laboratory methods used by geomorphologists to monitor and measure the impact of weathering and erosion on physical and mechanical properties of exposed rock surfaces and their immediate subsurface key advances are highlighted their application to multi scalar understanding and modelling of rock surface weathering in different contexts is discussed and potential future advances to provide new insights into rock weathering durability and materials conservation are identified in highlighting key advantages and disadvantages of a wide range of methods to the broader earth science community the paper aims to contribute to further innovative thinking across disciplines to develop new methods for measuring and monitoring rock weathering

the opening of the magellan strait and its geodynamic implications terra nova 25 13 20 2013 abstract the existence of a neogene quaternary rift system responsible for the opening of the eastern magellan strait has been one of the more peculiar tectonic features of the southernmost andes since its discovery more than a decade ago however until now there has been no explanation pinpointing the specific tectonic factors that led to the development of the rift this work focuses on the interaction between the fault systems and the tectonic regimes that have affected tierra del fuego north of the south america scotia left lateral strike slip plate boundary due to a good match between a jurassic extensional fault array orientation and the principal stress directions related to the strike slip plate boundary we conclude that jurassic transfer faults reactivated extensionally generating the magellan rift system this process was enhanced by northward continental drift and has implications for the geodynamic behind the separation of south america from antarctica

space geodesy constrains ice age terminal deglaciation the global ice 6g_c vm5a model a new model of the last deglaciation event of the late quaternary ice age is here described and denoted as ice 6g c vm5a it differs from previously published models in this sequence in that it has been explicitly refined by applying all of the available global positioning system gps measurements of vertical motion of the crust that may be brought to bear to constrain the thickness of local ice cover as well as the timing of its removal additional space geodetic constraints have also been applied to specify the reference frame within which the gps data are described the focus of the paper is upon the three main regions of last glacial maximum ice cover namely north america northwestern europe eurasia and antarctica although greenland and the british isles will also be included if peripherally in the discussion in each of the three major regions the model predictions of the time rate of change of the gravitational field are also compared to that being measured by the gravity recovery and climate experiment satellites as an independent means of verifying the improvement of the model achieved by applying the gps constraints several aspects of the global characteristics of this new model are also discussed including the nature of relative sea level history predictions at far field locations in particular the caribbean island of barbados from which especially high quality records of postglacial sea level change are available but which records were not employed in the development of the model although ice 6g c vm5a is a significant improvement insofar as the most recently available gps observations are concerned comparison of model predictions with such far field relative sea level histories enables us to identify a series of additional improvements that should follow from a further stage of model iteration

experiments on basin inversion above reactivated domino faults abstract results are presented from scaled sand box experiments which investigate the structural inversion of half graben basins generated by the contractional reactivation of extensional domino fault systems the overburden was deformed above a series of rigid basement fault blocks that were extended in a domino manner the models were constructed from either 1 sand with mica interlayers anisotropic behaviour 2 pure sand isotropic behaviour or 3 a sand clay mixture behaviour with increased competence during the extensional phase of deformation sand or alternating sand mica layers were deposited in teh half grabens associated with individual domino faults to simulate a syn extensional stratigraphic sequence together with a component of overall subsidence after termination of the extensional phase sand layers were added to represent a post rift passive subsidence stratigraphy subsequent contraction of the experimental configuration resulted in progressive reactivation of the domino fault system which was accompanied by back rotation of both the footwall and hanging wall in each of the individual fault blocks this produced null points along the profile section of the fault planes which separated net contraction above from net extension below continued shortening of the system led to further contraction being accommodated along footwall shortcut faults it is suggested that these shortcuts developed in response to 1 the accommodation of space problems generated by increased bed length in the graben acquired during extension and 2 by more efficient low angle fault trajectories in keeping with coulomb failure during horizontal to subhorizontal compression during inversion in the anisotropic model folding in the footwall partially suppressed the initiation of footwall shortcut faults footwall shortcut faulting did not occur in experiments where the dips of the original extensional faults were decreased before the inversion in all inversion experiments the contractional deformation associated with the shortening of the half graben was concentrated in the footwall to each domino basin bounding fault a control experiment in which an undeformed sand pack was deposited above an extended series of basement fault blocks revealed that the early extensional architecture formed in the other experiments had a profound influence on the resultant inversion geometries the results show clear similarities to interpreted examples of natural basin inversion structures associated with reactivated domino fault systems as well as to inferred strike slip induced flower structures

numerical simulation of mid holocene tidal regime and storm tide inundation in the south yangtze coastal plain east china abstract coastal flooding is reported as one of the major causes for the interruptions of neolithic cultures inhabiting the south yangtze coastal plain china during the middle holocene the archaeologically sterile transgressive sedimentary layers could be the results of extreme events or relative sea level rise induced by the enlargement of the local tidal range or global regional sea level rise to clarify the mechanism of the transgressive deposits at typical neolithic sites and the termination of neolithic liangzhu culture in the south yangtze coastal plain this study reconstructed the paleo topography at 7 6 6 4 and 4 5 cal ka bp on the basis of a database including 107 sediment cores and 644 radiocarbon ages and simulated the paleo tidal regimes and the inundation areas induced by typhoon events under the paleo topography and sea levels using a hydrodynamic model of high resolution changjiang estuary finite volume community ocean model ce fvcom the simulation results of tidal regimes showed that the tidal amplitude increased from 1 6 m to 2 2 m in the head of hangzhou bay induced by the paleo topographic change during the period 7 6 4 5 cal ka bp by contrast it reduced from 1 6 m to 1 0 1 2 m in the ningbo plain southeast of the bay which was unable to explain the long lasting marine inundation there and supported our previous assumption of an event of abrupt sea level rise at 4 5 4 4 cal ka bp simulation of the storm induced inundation further suggested that coastal flooding mainly occurred along the coastline of the taihu plain under the combined effect of tidal amplification and typhoon events at 4 5 cal ka bp while the inundation almost covered half of the taihu plain if all factors including tidal amplification extreme event and the abrupt sea level rise were considered we therefore suggest that the obvious increase in flood risk under the backdrop of sea level rise was a major cause for the abandonment of the liangzhu culture in the south yangtze coastal plain at around 4 4 cal ka bp

morphotectonics of the gorringe bank summit eastern atlantic ocean based on high resolution multibeam bathymetry abstract high resolution swath bathymetry of the gorringe bank located along the europe africa obliquely convergent plate boundary offshore sw portugal allowed investigation of its shallow depth morphotectonic structure as a contribution to understanding the interplay of sea level changes and active deformation of the region dominant ene wsw to nne wsw and subordinate nw se trending morphologic alignments were mapped on the digital terrain model dtm built from multibeam data for both the gettysburg and ormonde summits of the bank based on appraisal of regional structural and seismological data the dominant and subordinate sets are interpreted to reflect dip slip to left oblique reverse faults and normal faults or dyke like joints respectively several terrace remnants were mapped on the dtm and were grouped into five orders at depths ranging from 40 to 120 m morphological features suggest that the terraces were formed in a coastal environment likely during middle late pleistocene sea level changes the terraces are probably polycyclic implying minor vertical tectonic motion however the whole terrace set except the deeper and younger one which was mainly shaped during the lgm lowstand is consistently up to 10 m lower at ormonde in the east relative to gettysburg in the west suggesting displacement across a nne ssw striking fault mapped in the saddle between the two seamounts the structure assemblage is argued to represent the shallow splay system of a crustal scale fault ramp underlying the bank the ene wsw reverse faults have a southward polarity and together with the overall northwest tilt of the bank point to displacement toward the horseshoe abyssal plain to the south at least at upper crustal levels

sandbox model studies of inversion tectonics abstract scaled plane strain sandbox models have been used to simulate basement controlled structural inversion in a sedimentary overburden two basement configurations were tested in the first one reversal of movement along vertical and normal faults that controlled a graben relief induced only a partial recovery of displacement along the pre existing overburden faults the inversion produced new reverse faults in the footwall of the pre existing overburden faults the reactivated normal faults and the new reverse faults defined wedge shaped fault blocks at the edges of the inverted structure in the second configuration the relationship between inversion and tilted fault blocks was tested when a tilting basement block does not move parallel to its bounding fault a compression is induced in the overburden which generates an inverted structure bounded by new reverse faults both experiments show that structural inversion not only reactivates pre existing faults but also generates new faults in the overburden faults related to inversion are the result of horizontal compression either associated with rotation of one of the fault blocks or with vertical uplift of basement blocks

stepwise accelerations in the rate of sea level rise in the area north of tokyo bay during the early holocene abstract tokyo bay is situated near the triple junction of the north america pacific and philippine sea plates where relative sea level changes since the last glacial maximum lgm have been strongly affected by subduction tectonics in this study 55 sea level index points were extracted from the post lgm incised valley fills beneath the lowlands north of tokyo bay and used to construct a detailed relative sea level curve for the early holocene sea level jumps were detected at 10 1 10 0 9 2 9 1 and 8 9 8 7 ka each of 2 7 m and each followed by an acceleration in the rate of sea level rise these paired phenomena are attributed to coseismic subsidence and an interseismic decrease in the rate of uplift respectively the early holocene sea level changes in tokyo bay are characterized by remarkably short sea level jumps of

sandbox experiments on basin inversion testing the influence of basin orientation and basin fill analogue modelling experiments using brittle materials are performed to study the inversion of extensional structures asymmetric grabens of two different orientations are first created during a phase of extension and progressively filled they are subsequently shortened in the same direction the aim of our experiments is to determine factors affecting the style of deformation during inversion we specifically investigate variations in thickness and distribution of strong and weak layers constituting the graben fill and in initial basin orientation the main advantage of our experimental set up is that we have a complete control on graben location width infill and orientation before inversion the experiments show that shortening results only in limited reactivation of pre existing normal faults in general forward thrusts and backthrusts cut across normal faults into the footwall of the graben the forward thrusts either propagate parallel to the enveloping surface of faulted blocks or they cut across basin limiting normal faults at various angles the graben fill is mechanically extruded by displacement along forward thrusts that accommodate most of the shortening both pre existing faults and weak graben fill act as zones of weakness during inversion and determine the orientation and location of both backthrusts and forward thrusts the results of our experiments conform well to natural examples of inverted graben structures

rates and patterns of erosion on inter tidal shore platforms kaikoura peninsula south island new zealand this paper presents measured rates of erosion on shore platforms at kaikoura peninsula south island new zealand surface lowering rates were measured with a micro erosion meter and traversing micro erosion meter the mean lowering rate for all shore platforms was 1 130 mm a 1 differences in lowering rates were found between different platform types and lithologies the rate of surface lowering on type a sloping mudstone platforms was 1 983 mm a 1 and 0 733 mm a 1 on type b mudstone platforms subhorizontal on limestone platforms the lowering rate was 0 875 mm a 1 a previously reported cross shore pattern of surface lowering rates from kaikoura was not found rates were generally higher on the landward margins and decreased in a seaward direction season is shown statistically to influence erosion rates with higher rates during summer than winter the interpretation given to this is that the erosive process is subaerial weathering in the form of wetting and drying and salt weathering this is contrary to views of shore platform development that have favoured marine processes over subaerial weathering copyright 1998 john wiley sons ltd

systematic analysis of rocky shore platform morphology at large spatial scale using lidar derived digital elevation models abstract much of the existing research on rocky shore platforms describes results from carefully selected field sites or comparisons between a relatively small number of selected sites here we describe a method to systematically analyse rocky shore morphology over a large area using lidar derived digital elevation models the method was applied to 700 km of coastline in southwest england a region where there is considerable variation in wave climate and lithological settings and a large alongshore variation in tidal range across shore profiles were automatically extracted at 50 m intervals around the coast where information was available from the coastal channel observatory coastal classification routines were developed to automatically remove non platform profiles the remaining 612 shore platform profiles were then subject to automated morphometric analyses and correlation analysis in respect to three possible environmental controls wave height mean spring tidal range and rock strength as expected considerable scatter exists in the correlation analysis because only very coarse estimates of rock strength and wave height were applied whereas variability in factors such as these can locally be the most important control on shoreline morphology in view of this it is somewhat surprising that overall consistency was found between previous published findings and the results from the systematic automated analysis of lidar data platform gradient increases as rock strength and tidal range increase but decreases as wave height increases platform width increases as wave height and tidal range increase but decreases as rock strength increases previous studies have predicted shore platform gradient using tidal range alone a multi regression analysis of lidar data confirms that tidal range is the strongest predictor but a new multi factor empirical model considering tidal range wave height and rock strength yields better predictions of shore platform gradient root mean square error of predictions reduced by 5 the key finding of this study is that large scale semi automated morphometric analyses have the potential to reveal dominant process controls in the face of small scale local variability

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

evolution and inheritance of a rock coast western galicia northwestern spain there is increasing evidence that shore platforms and other elements of rock coasts may be inherited at least in part from interglacial stages when sea level was similar to today s most of this evidence which includes ancient beaches and datable terrestrial deposits has been obtained from areas of resistant slowly eroding rock where the platforms often appear to be much too wide to have developed since the sea reached its present level it is much more dif cult to demonstrate that inheritance has occurred in areas of weaker rock which generally lack any datable material the coast of western galicia in northwestern spain has shore platforms in igneous and metamorphic rocks that were deeply weathered during the tertiary these platforms are closely associated with ancient beaches from the last interglacial stage and associated periglacial and uvio nival deposits that covered and fossilized most of the eemian platforms and cliffs during the late middle and late weichselian glacial stage the sedimentary processes and the thickness and facies of the sediments were determined by the height aspect and gradient of the coastal mountains and their distance from the coast radiocarbon dating sedimentary analysis and platform morphology indicate that the shore platforms of galicia have been inherited from at least the last interglacial stage they were fossilized in places beneath thick weichselian deposits and then exhumed during the holocene transgression the abundant evidence for inheritance in galicia has important implications for other coasts in fairly weak rocks where such evidence is generally lacking copyright 2003 john wiley sons ltd

late pleistocene changes of tidal amplitude and phase in osaka bay japan reconstructed from fossil records and numerical model calculations abstract calculations with a numerical model of the seto inland sea tides show that sea level changes cause strong changes in the tidal range and pattern of diurnal inequality in osaka bay a higher sea level produces a stronger diurnal inequality and a smaller tidal range a lower sea level produces a weaker diurnal inequality and a larger tidal range the best fit between the calculated tidal patterns and the tidal pattern that is reconstructed from the growth structures of fossils from the last interglacial is achieved with a sea level approximately 15 20 m lower than present for a such sea level and tidal pattern the numerical calculation gives a tidal range of about 2 65 2 8 m in osaka bay

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

modelling the effect of pliocene quaternary changes in sea level on stable and tectonically active land masses a mathematical model was used to examine the effect of pliocene and quaternary changes in sea level on the development of tectonically active and inactive rock coasts the model calculated rates of mechanical wave erosion according to such factors as the deep water wave regime bottom topography and surface roughness and the resistance of the rocks subaerial terraces were truncated or eliminated by subsequent terrace formation at lower elevations especially on steeply sloping landmasses experiencing slow rates of uplift submarine terraces formed during glacial stillstands were best preserved when rapid subsidence quickly carried them below the level of wave action on slowly subsiding landmasses submarine terraces formed during interglacials and glacial periods experienced repeated erosional modification during subsequent periods of rising and falling sea level and were generally less distinctive on rapidly rising or subsiding 5 mm yr 1 landmasses terraces that formed during interglacial stages alternated above and below present sea level with terraces formed during glacial stages despite some differences in terrace occurrence and elevational distribution it may be difficult to distinguish profiles cut during accelerating or decelerating uplift the amount of erosion during sea level oscillations increases with oscillation amplitude and the larger oscillations in the middle to late quaternary were therefore more conducive to erosion than the smaller oscillations of the pliocene and early quaternary the effect of oscillation amplitude may have been countered during the earlier stages of profile development however by steeper submarine gradients and reduced rates of wave attenuation copyright 2014 john wiley sons ltd

sea saltwater weakening of chalk and the impact on cliff instability chalk forms one of the major coastal cliff formations throughout northwest europe with large population centres and critical infrastructure being exposed to and at risk from cliff collapses in this rock type traditionally the two main factors leading to chalk cliff collapse have been considered to be i waves attacking and eroding the base of the cliff and ii water weakening as the chalk becomes saturated this work challenges the established view by identifying the role of salt from seawater in the degradation of porous rocks in coastal environments as a third and potentially the most important mechanism leading to chalk cliff collapse field and laboratory investigations have identified and quantified the role of sea saltwater weakening of chalk in coastal environments a series of triaxial strength tests have identified that coastal chalks are up to 55 weaker than their inland equivalents this weakening process is as a result of saltwater ingress into the chalk sem imaging has shown that seawater penetrates the porous chalk and the salt progressively concentrates forming salt crystals which disrupt the pore structure and weakening the rock material which then leads to catastrophic cliff failure saltwater weakening of cliffs could be one of the main factors leading to large and small scale collapses observed along the chalk coast line and is likely to be the primary reason for the increasing frequency of cliff failures along protected coastal sections as the sea salt progressively concentrates in the cliff reducing its mechanical strength rock strength is not usually considered to be temporally variable and is therefore rarely considered in relation to climate change however this is not true of soft rocks like chalk which weaken and collapse in short time periods as they are exposed to external factors

the control of pre existing extensional structures on the evolution of the southern sector of the aconcagua fold and thrust belt southern andes abstract the aconcagua fold and thrust belt located in the andean mountains at 32 30 to 34 s has been described as a classic model of a thin skinned thrust belt however new structural data from its southern sector have shown that it has a complex structural framework reflected in multiple mesozoic extensional phases overprinted by structural inversion as well as thin and thick skinned tectonics two major superimposed extensional structural styles have been identified for the mesozoic characterized by distinctly oriented stress fields a key role in the evolution of this part of the fold and thrust belt was played by a late triassic to early jurassic depocentre and by late jurassic block faulting shortening was accommodated by a combination of inversion of pre existing normal faults development of footwall short cuts and both thin and thick skinned thrusting synrift and postrift sedimentary rocks were uplifted by reactivation of normal faults with further shortening along newly formed thin skinned thrust faults the geometry of thin skinned fault systems is controlled by the architecture of the rift basin competent footwalls forming barriers to the lateral propagation of detachments

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

modeling the effect of late quaternary interglacial sea levels on wave cut shore platforms abstract a mathematical wave erosional model was used to study the effect of high sea levels during the penultimate oxygen isotopic stage 7 and last interglacials substage 5e and in the late holocene stage 1 on the present morphology of wave cut shore platforms sea level was considered to have been either the same as today or 2 25 m lower during the penultimate interglacial and 2 25 4 5 or 6 75 m higher than today during the last interglacial stage the model suggested that inherited gently sloping shore platforms in resistant rocks may be essentially protected today from erosion by high storm waves the lowest platform gradients were in runs with mesotidal 3 m range and usually with low wave periods low surf attenuation rates and weak rocks modern platform gradients increased with the difference in elevation between sea levels during successive interglacial stages shore platforms were widest in runs in which sea level was the same as today in the penultimate interglacial and 4 5 m higher than today during the last interglacial constant sea level and high last interglacial sea levels with considerable overlapping between the zones of high duration values between the mean neap high and low tidal levels in stages 7 5e and 1 were conducive to the development of wide shore platforms whereas sea levels lower than today s in stage 7 tended to produce narrower platforms in general higher sea levels during the last interglacial tended to produce higher cliff platform junctions than constant sea level unless the sea was lower than today during the penultimate interglacial stage there was a lack of supratidal ledges in macrotidal 9 m model runs with high initial gradients this suggests that gently sloping inherited shore platforms are essential for the subsequent development of supratidal nonstructural ledges in high tidal environments during periods of higher sea level intertidal ledges developed in the upper portion of the modern intertidal zone under a variety of tidal and sea level conditions these ledges can develop independently of lithological or structural influences and without any change in sea level a single high sea level may also simultaneously produce two ledges at different supratidal elevations in mesotidal environments

rates and patterns of bedrock denudation by coastal salt spray weathering a seven year record rapid surface lowering of bedrock is taking place in the supratidal zone by salt spray weathering a seven year run of data demonstrates a mean rate of lowering of 0 625 mm a 1 considerable variation exists in annual point lowering values within measurement sites although between site variation is not significant aggregate year to year variations in surface lowering are not significant spatial variation in individual point values may be compensated by temporal variation over an 11 year period there is a marked summer maximum in surface lowering rate and this is strongly correlated with monthly air temperature spatially and temporally episodic swelling of the rock surface is demonstrated this does not correlate statistically with any available climatic variable and is deemed to be a real and largely stochastic phenomenon it is interpreted as rock bursting at the granular scale due to haloclasty the processes most likely to be responsible for the observed rapid denudation are crystallization and thermal expansion of halite both of which are enhanced by high summer temperatures

the analysis of last interglacial mis 5e relative sea level indicators reconstructing sea level in a warmer world the last interglacial mis 5e 128 116 ka is among the most studied past periods in earth s history the climate at that time was warmer than today primarily due to different orbital conditions with smaller ice sheets and higher sea level field evidence for mis 5e sea level was reported from thousands of sites but often paleo shorelines were measured with low accuracy techniques and in some cases there are contrasting interpretations about paleo sea level reconstructions for this reason large uncertainties still surround both the maximum sea level attained as well as the pattern of sea level change throughout mis 5e such uncertainties are exacerbated by the lack of a uniform approach to measuring and interpreting the geological evidence of paleo sea levels in this review we discuss the characteristics of mis 5e field observations and we set the basis for a standardized approach to mis 5e paleo sea level reconstructions that is already successfully applied in holocene sea level research application of the standard definitions and methodologies described in this paper will enhance our ability to compare data from different research groups and different areas in order to gain deeper insights into mis 5e sea level changes improving estimates of last interglacial sea level is in turn a key to understanding the behavior of ice sheets in a warmer world

modelling the development of rocky shoreline profiles along the northern coast of ireland abstract a mathematical wave erosion model is used to simulate postglacial shoreline profiles along the rocky high energy coast of the north of ireland the wave erosion model is driven by a suite of relative sea level rsl curves for the last 16 000 years produced from four glacial rebound models multiple runs are performed with different initial shore profiles and rock resistances to investigate shoreline evolution and the significance of inherited morphology on the resultant profile shape the simulated profiles are then compared with mapped profiles from three areas of the north of ireland with different lithological and hydrographic properties modelled profiles generally replicate the overall mean shoreline gradients observed across the region when rock resistance is relatively high and erosion rates correspondingly low in these profiles breaks in mean slope are observed at depths comparable to the rsl minima in several of the rsl scenarios at c 10 m 15 m and 20 m for north antrim derry and donegal respectively at portrush and portballintrae derry profiles may be influenced by structural controls relating to the underlying basalt surface and the removal of overlying glaciogenic sediments all rsl scenarios replicate the observed eastward increase in cliff platform junction height reflecting the differential glacioisostatic rebound experienced along the coast however the precise elevation at which the simulated cliff base occurs is sensitive to the choice of rsl scenario suggesting that this parameter may prove useful in evaluating glacial rebound model performance several of the rsl scenarios generate raised shore platforms or terraces in north antrim and derry at heights comparable to raised shoreline features reported in the literature however no single curve or combination of parameters is capable of generating the range of platform and terrace features observed in the bathymetric and topographic data these misfits are consistent with the idea that many rock platform or terrace features are inherited from an earlier phase or phases of rsl

basin inversion and contractional reactivation of inherited normal faults a review based on previous and new experimental models abstract compressional inversion of former extensional sedimentary basins is a particularly common phenomenon given that passive margins share the same destiny of being subsequently incorporated into fold and thrust belts during basin inversion pre existing faults may concentrate stress and localise future thrust ramps or may be reactivated recording reversal of movement from extension to reverse this process has attracted attention largely because of its economic implications related to petroleum and ore deposit prospects and seismic hazard assessment since more than two decades analogue modelling has been used to indentify and or test a number of parameters relevant for the inversion process this paper aims therefore to offer a reasoned review of the analogue modelling work done on the subject coupling such previous results with those of a new experimental series inspired to the northern apennines stratigraphy and evolution past models have explored the role of main factors governing fault reactivation susceptibility such as fluid pressure fault weakness fault steepness angle of shortening and sediment loading the new models have addressed the role played by geometry and strength of a basal ductile layer during inversion two sets of sand silicone models were first extended orthogonally at different velocities to produce dissimilar pre inversion internal geometries and then shortened coaxially at different velocities to vary the brittle ductile coupling the experimental results confirm the selectiveness of fault inversion and reveal strong similarities with structural styles of tectonic inversion reported from the northern apennines and various areas worldwide the preferred geological model inferred from this modelling involves contribution of 1 syn inversion rotation of pre existing faults to shallower dip and 2 rotation of principal stress axes which could explain the invariable reactivation of only one of the two oppositely dipping graben bounding faults these factors would thus interact with the other well established parameters controlling the fault reactivation process

cenozoic crustal thickening wrenching and rifting in the foothills of the southernmost andes abstract the southernmost andes form an orocline between the patagonian cordillera trending n s and the fueguian cordilleras trending e w on the foreland side is the magellan basin the area has a history of paleozoic compression triassic to early cretaceous rifting and late cretaceous to quaternary compression in response to changing plate tectonics major structures of late cretaceous and cenozoic age vary along the strike in the patagonian cordillera and foothills folds and thrusts trend nnw slightly oblique to the orogen whereas strike slip faults are parallel to the orogen and right lateral in the fueguian cordilleras and foothills folds and thrusts trend ese slightly oblique to the orogen whereas strike slip faults are parallel to the orogen and left lateral in the axial zone of the magellan basin folds and thrusts are parallel to the orogen and rifts are sub perpendicular to it to a first approximation the pattern of structures has mirror symmetry about the axis of the magellan basin in detail however wrenching appears to be more prevalent in the fueguian cordillera and foothills than it is in the patagonian cordillera and foothills minor faults of cenozoic age are common in the foothills from a kinematic analysis of fault slip data 1 shortening and stretching directions are mostly sub horizontal 2 shortening directions vary in trend from ene in the patagonian foothills to ne in the fueguian foothills and 3 stretching directions are sub parallel to traces of major thrusts in the fueguian cordillera and foothills strike slip faulting is prevalent in the patagonian foothills crustal thickening is prevalent over strike slip faulting the kinematics reflect a combination of thrusting and wrenching and they are consistent with the major structures to investigate the origin of the cenozoic structures we used analogue models on a fully lithospheric scale where an oceanic plate subducted beneath a continental corner the corner was an area of transition from frontal subduction to transcurrent motion the boundary conditions may not have been fully realistic but the experiments did account for the major elements of the structural pattern in southernmost south america including rifts that are perpendicular to the orogen and counterclockwise block rotations

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

tidal amplitude decreases in response to estuarine shrinkage tokyo bay during the holocene abstract tidal changes in tokyo bay during the last 10 000 years were investigated by combining a numerical model with newly compiled model bathymetries for the present day the early 20th century and every 1000 years from 4000 to 10 000 years ago over this time period sea level has changed by more than 30 m and the coastline has shifted 50 60 km tides during the early 20th century and 4000 9000 years ago were larger than those at present from 9000 to 4000 years ago the bay setting was mesotidal in contrast to the modern microtidal setting the maximum tidal level at the head of the bay was 72 higher 7000 years ago than at present and m2 tidal currents at the bay mouth from 10 000 to 9000 years ago were three times stronger than those at present when tides were compared at a fixed location the greatest tidal enhancement was found to have occurred 9000 years ago the weakening of tides over the last 9000 years can be explained by introducing the concept of estuarine shrinkage together with quarter wavelength resonance theory tidal weakening occurred in two phases during the first phase 9000 7000 years ago it was due to the rise in sea level type 2 shrinkage and during the second phase a decrease in the length of the bay was responsible type 1 shrinkage these findings can be applied to the assessment of both past tidal changes and potential future tidal changes in other elongated estuaries with lengths of several tens of kilometers

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

oblique half graben inversion of the mesozoic neuquen rift in the malargue fold and thrust belt mendoza argentina new insights from analogue models abstract the malargue fold and thrust belt located in the andean mountains between 34 s and 36 30 s formed in response to contraction during cenozoic times its structural style and geometry was controlled by the mesozoic rift system that formed the neuquen basin in west central argentina the rift architecture in the southern sector of this belt was previously interpreted in terms of the present n s compressive structural trends assuming the inversion of pre existing normal faults with the same orientation here we propose that the nw se trending el manzano liu cullin lineament located in the northern termination of the sierra azul reflects the presence of a half graben master fault in the subsurface this hypothesis is supported by subsurface data a balanced cross section and it is tested using a series of scaled sandbox analogue models we suggest that the lineament responds to a reactivated nw trending half graben fault hidden by the mainly n s trending andean structures the proposed orientation is in agreement with the ne sw extension developed in the neuquen basin during the triassic early jurassic the modeling of the inverted oblique half graben reveals that the strikes of the main structures of inversion related belts may often be independent of the orientation of the previously developed extensional system providing a new perspective for their interpretation

can shore platforms be produced solely by weathering processes field measurements and laboratory experiments provided data on surface downwearing rates on horizontal mesotidal and sloping macrotidal shore platforms in eastern canada the experimental data were used in a simple mathematical model to determine whether weathering acting alone can produce shore platforms the model failed to produce realistic platform profiles it did not account for the relationship in the field between platform gradient and tidal range and downwearing rates were much too low to produce wide platforms in the few thousand years that the sea has been at its present level although weathering undoubtedly plays an important role in the development of shore platforms it cannot by itself account for characteristic differences in platform morphology in different morphogenic environments it seems more likely that platform morphology is the result of mechanical wave erosion controlled by the tidally controlled expenditure of wave energy and some related or independent mechanism that controls weathering efficacy at different tidal elevations according to the tidal range

global glacial isostasy and the surface of the ice age earth the ice 5g vm2 model and grace abstract the 100 kyr quasiperiodic variation of continental ice cover which has been a persistent feature of climate system evolution throughout the most recent 900 kyr of earth history has occurred as a consequence of changes in the seasonal insolation regime forced by the influence of gravitational n body effects in the solar system on the geometry of earth s orbit around the sun the impacts of the changing surface ice load upon both earth s shape and gravitational field as well as upon sea level history have come to be measurable using a variety of geological and geophysical techniques these observations are invertible to obtain useful information on both the internal viscoelastic structure of the solid earth and on the detailed spatiotemporal characteristics of glaciation history this review focuses upon the most recent advances that have been achieved in each of these areas advances that have proven to be central to the construction of the refined model of the global process of glacial isos

extensional fault systems in sedimentary basins a review of analogue model studies abstract scaled analogue models have provided graphic new insights into the progressive development of extensional fault systems this paper reviews recent results of an on going analogue modelling programme and compares the structural styles in the models with examples of natural extensional fault systems four fundamental model styles scaled to simulate deformation in brittle sedimentary rocks in the upper 10 km of the crust are reviewed extension above a basal detachment which undergoes stretching over a limited are produces an asymmetric rift graben bounded by planar faults and in which the internal deformation is accommodated by rotational domino faults these experimental results are directly comparable to structures found in intracontinental rifts extension above a basal detechment which undergoes extension under the whole model and which has no constraints at the ends produces domino style fault arrays in the pre rift sequence and listric growth faults in the syn rift sequence these results compare with highly extended rift basins and terranes such as the basin and range province usa extension above a simple listric fault produces a characteristic hangingwall roll over and crestal collapse graben system at high values of extension superposed crestal collapse grabens occur and a fan of listric growth faults is developed these structures bear striking similarities to growth faults in progradational delta systems ramp flat listric extensional fault systems using sand mica models produce a characteristic family of structures with an upper roll over crestal collapse system a ramp syncline and reverse fault fold zone and a lower roll over crestal collapse system an example of a ramp flat fault system from the gulf coast usa is presented as a comparison with the analogue model results preliminary results of three dimensional extensional model experiments are presented to illustrate the complexities in such fault systems in all of the experimental models it is found that the geometry of the underlying detachment system exerts fundamental control on structures produced in the hangingwall the analogue models illustrated in this review provide valid geometric and kinematic templates for the progressive evolution of extensional fault systems in sedimentary basins

geomorphology and clast assemblages of intertidal beachrock implications for submerged shoreline preservation abstract beachrock may be considered a reliable indicator of sea level in addition to a reliable and recognizable source for onshore movement of beachrock clasts by overwash processes associated with extreme events key to this is its geomorphology and preservation potential both of which are poorly understood here we examine the processes and deposits associated with beachrock breakdown from camurupim ne brazil and compare its preservation to beachrocks found on continental shelves in south africa we study a prominent and continuous 50 60 m wide beachrock complex that crops out along a 10 km stretch of coastline and which mostly comprises 1 5 to 2 m thick trough crossbedded sandstones these have generated large joint bounded blocks that have been transported landwards under extreme energy conditions based on numerical modelling and comparisons to the contemporary wave climate tabular clasts have accumulated as isolated very coarse boulders on the seaward margin small clasts in various topographic traps boulder ridges with large landward and seaward dipping clasts on the uppermost part of the outcrop and subaqueous and subaerial washover fans isolated fine meso boulders emplaced during extreme waves hs ca 12 m exhibit fitted textures and pressure solution contacts pointing to subsequent rocking and shaking smaller clasts in boulder ridges and overwash settings are initially liberated and transported by waves within the annual decadal frequency spectrum deposited on the high points of the outcrop subsequent movement during less extreme wave action progressively transports the clasts across the surface where they are often trapped in the fitted fabric on top of the platform our breakdown model and overall beachrock preservation scheme is consistent with reported seismic signatures of submerged holocene beachrock shorelines beachrock preservation during transgression is strongly influenced by the original sedimentary facies thick trough crossbedded joint bound clasts preserve the former shoreline clasts from the planar units accumulate as washover fans to landwards of the ridge