geology u pb geochronology and stable isotope geochemistry of the tunca semi massive sulfide mineralization black sea region ne turkey implications for ore genesis abstract upper cretaceous volcano sedimentary sequences of the eastern pontide orogenic belt ne turkey are host to significant vms mineralization including near tunca the initial stages of felsic volcanism within the mineralized area are marked by the eruption of dacitic lavas and breccias of the kizilkaya formation this was accompanied by the emplacement of domelike hematitic dacites autobrecciated and volcaniclastic rocks both in situ and resedimented were likely generated from extrusive portions of these dacite bodies basaltic volcanism is marked by the eruption of the lava flows and pillow lavas of the caglayan formation hiatuses in basaltic activity are marked by thin horizons of volcaniclastics and mudstones the uppermost felsic volcanic units were accompanied by resedimentation of autoclastic facies from previous volcanism and represent the latest phase of upper cretaceous volcanism in the area the semi massive sulfide mineralization is associated with a late stage of the initial felsic volcanism u pb la icp ms zircon dating of a dacitic tuff breccia yielded an age of 88 1 1 2 ma coniacian upper cretaceous which is interpreted to be the age of the sulfide occurrences a concentric zoned alteration pattern is observed in the footwall rocks the alteration pattern is considered to have formed by lateral migration of hydrothermal fluids which had ascended along the discharge conduit fluid inclusion data indicate precipitation or mobilization processes within a relatively narrow temperature range of 152 255 c avg 200 c the low salinity fluids in the fluid inclusions less than 5 9 wt nacl equivalent are consistent with typical modified seawater dominant hydrothermal vent fluids sulfur isotope analysis of the tunca sulfides yields a narrow range of 1 5 4 1 per mil these 34 s values are also typical of many vms deposits most of the recorded 18 o values 7 1 to 14 0 per mil are greater than 9 per mil the most intensely hydrothermally altered rocks tend to have lower 18 o values relative to the less altered rocks collectively the geologic relationships mineralization style and the lack of seafloor ore facies suggest that mineralization is principally of sub seafloor origin the most geologically reasonable interpretation of the genesis of the tunca mineralization is the continuous interaction between the host rocks and seawater derived fluids without significant involvement of a magmatic fluid

quantitative roundness analysis of coastal boulder deposits abstract the sedimentology of coastal boulder deposits cbd is little known these deposits and especially the largest clasts within them which commonly weigh many 10s of tonnes are of increasing interest because they attest to extreme energy wave events acting well above the high tide mark in some cases 40 m above high water and 100 m inland recent observations have made clear that storm waves rather than tsunami are important in both creating and activating these deposits but beyond that we know little about their hydrodynamics or the relative frequency of boulder movement and how this might vary with topographic setting roundness is a first order characteristic that preserves a record of deposit reworking it can tell us whether clasts move around much after they have been created from bedrock or whether they are emplaced into cbd with little or no subsequent transport but because roundness has historically been difficult to measure most roundness estimates in the literature are based on qualitative visual assessment and are therefore of limited analytical value fully reproducible roundness measurements are possible however and in the case of boulders they can be acquired quite easily using the kirkbride 2005 device in combination with a trigonometric formula presented here cbd at locations in ireland and scotland provide a test case demonstrating the utility of quantitative boulder roundness measurements the 567 clasts we measured are generally angular but a substantial proportion shows some degree of rounding most importantly there are demonstrable consistent patterns relating topography and roundness there is a strong and unsurprising inverse correlation between clast roundness and deposit elevation there is no first order relationship between roundness and inland distance but there is a power law inverse relationship between rounding and steepness ratio of elevation to distance inland the greatest degree of rounding is found in cbd located at the back of gentle coastal platforms with gradual slopes these relationships provide new insights into cbd sedimentology which we hope will be probed and tested in future studies

sea level change and superstorms geologic evidence from the last interglacial mis 5e in the bahamas and bermuda offers ominous prospects for a warming earth abstract geological observations from last interglacial lig mis 5e eemian carbonate landscapes in the bahamas and bermuda reveal a turbulent climate transition at the close of the peak interglacial the interval is associated with rapid multi meter shifts in sea level as major ice sheets melted and or collapsed sedimentary evidence from the eastern bahamas includes wave transported megaboulders lowland chevron storm ridges and hillside runup deposits this trilogy collectively provides direct geological evidence of frequent intense storms generating sustained long period waves from the northeast atlantic ocean penecontemporaneous with wave deposits is the subtidal production and flux of a massive volume of ooid sediments associated with amplified winds and storminess during the latter half of mis 5e that resulted in exponential island growth steeper temperature and pressure gradients were evident in the north atlantic ocean while the southern ocean appears to have had a major role in affecting atmospheric co2 as warming of the southern ocean drives ventilation of the deep ocean co2 in turn acts as a tight control knob on global climate the dramatic oceanographic and island building events of late mis 5e are unique among other interglacial periods of the past half million years the lig record reveals that strong climate forcing is not required to yield major impacts on the ocean and ice caps antarctic ice cores document that lig atmospheric co2 was 275 ppm while global temperature was in terms of lyellian uniformitarian principles the trilogy of coeval deposits of mis 5e described herein do not translate to our modern climate parameters and further cannot be explained by coincidental megatsunami in our industrial world rapidly increasing atmospheric co2 rates 2 ppm yr have surpassed 408 ppm levels not achieved since the pliocene 3 ma ago while global temperature increased 1 c since the 1870s with greatly increased co2 forcing at unmatched rates except perhaps during global extinction events dramatic change is certain in the interest of our future world we must seek to understand the complex set of linked natural events and field observations that are revealed in the geology of past warmer climates

quarrying transport and deposition of cliff top storm deposits during extreme events banneg island brittany abstract on 10 march 2008 a particularly high energy storm hit the french atlantic coast and the western part of the english channel this storm did not generate exceptionally high waves significant and maximum wave heights recorded in the iroise sea brittany reached 10 85 and 18 17 m respectively whereas during the 1989 90 winter storms they had reached 12 and 20 m respectively the exceptional character of the march 2008 storm event arises from the fact that it occurred during an exceptional spring tide from a morphogenetic point of view the effects of this storm in terms of block quarrying transport and deposition on banneg island brittany were significant this study shows that the weight of the blocks displaced during the event was between 0 07 and 42 64 t with a median value of 0 72 t more than 60 of the blocks were quarried from the wave scoured cliff top platform demonstrating that the favoured zone for supplying material was located inland of the cliff two dominant modes of transport were involved depending on the relationship between extreme water levels and cliff height at the centre of the island the height of the waves breaking over the top of the cliffs on the western coast resulted in a torrential surge that flowed out towards the eastern coast of the island over a landward sloping platform on the western coast of the island blocks weighing between 0 3 and 1 4 t were displaced between 50 and 90 m from the cliff edge by this flow at the flow outlet on the eastern coast 90 m from the western cliff edge a pit 1 6 m deep was excavated at porz ar bagou cove and some of the mobilised blocks were deposited in two parallel lobes about 40 m seaward of the eastern shoreline elsewhere on the island block transport occurred by airborne projection although wave heights were lower than the altitude of the cliffs the pressure exerted by breaking waves on the bedrock was sufficient to quarry and displace blocks a temporal comparison of the changes recorded in the double and triple boulder ridges showed that the most seaward ridges were practically untouched with the most important changes occurring in the second and third ridges these observations allow us to propose a spatio temporal model for the accretion of cliff top storm deposits ctsds with the various stages of ctsd formation being directly related to the morphological evolution of the cliff

boulders of mis 5 age deposited by a tsunami on the coast of otago new zealand abstract a series of elevated imbricated boulders were investigated on the otago coastline southeast new zealand through field surveying and optical luminescence dating by using established hydrodynamic relationships of sediment transport the energy required to move the clasts was calculated and compared to the historic record of marine inundations of that coast the boulders are platy in shape and are over 2 m long in some cases and are sourced from a locally outcropping conglomerate unit which appears to be the only lithology on this section of coast that erodes to produce clasts of this size it is estimated that the boulders were deposited by a tsunami between 2 and 3 m high during the latter part of marine isotope stage 5 they therefore represent the first pre holocene tsunami deposit and one composed of large boulders described on the new zealand coastline

modelling the processes of cliff top erosion and deposition under extreme storm waves at exposed sites on the deep water coasts of the british isles cliff top storm deposits ctsds occur on cliffs at a variety of elevations above sea level and may occasionally reach up to 50 m above sea level time series field mapping of ctsds has demonstrated their formation over the historical period and their continued modification during major past storms this paper seeks to clarify the morphogenetic context of ctsds model the wave conditions and forces encountered at the cliff face and cliff top platform and propose mechanisms to link wave processes to cliff face quarrying and landwards cliff top transport of quarried blocks to deposition zones at the rear of the cliff top platform we report on wave tank experiments using scaled cliff and wave conditions from a cliff in the shetland islands to focus on three situations incident waves lower than the cliff edge height at the same height as the cliff edge height and higher than the cliff edge height the modelling suggests that steep waves of 10 m and above impacting on a 15 m high cliff will result in impact pressures sufficient to promote crack propagation block detachment and lifting of large blocks large but not necessarily steep waves of the same height as the cliff edge produce sufficient impact pressures and water flow over the cliff edge and platform to entrain blocks transport and deposit them on the cliff top where cliff top height is below wave crest elevation green water bore flow occurs sufficient to force rotation or lifting of blocks out of cliff top and cliff top platform sockets high flow velocities rapidly accelerate and transport blocks inland until the flow attenuation results in deposition of blocks at the limit of run up the model results provide a good explanatory framework to account for the quarrying of the upper part of the cliff face and cliff top platform under storm wave conditions and provide an insight into the exceptional velocities experienced over the cliff top platform under bore flow conditions the modelling results show that extreme storm waves are capable of quarrying transporting and depositing large blocks at altitude and significant distances inland and so present serious questions about the use of such deposits as diagnostic of palaeo tsunami

boulders as a signature of storms on rock coasts this paper is the first review of coastal boulder studies it serves as a peer reviewed introduction to a special issue on the topic of boulders as a signature of storms on rock coasts since 2004 and the indian ocean tsunami most coastal boulder research has been focused on using boulders as sedimentary signatures of palaeo tsunami events and the most commonly used transport equations typically suggest that large boulder deposits are products of tsunami rather than storms there is growing empirical evidence demonstrating on inter annual to century timescales that storm waves are capable of transporting and depositing boulders of significant size at elevations well above sea level current process studies of how boulders are eroded transported and deposited have not received wide attention by rock coast geomorphologists or palaeoenvironmental reconstruction scientists this special issue is framed around the goal of highlighting our current understanding of the role of storm waves as a driving mechanism for boulder erosion transport and deposition here we review the current state of knowledge about boulder dynamics boulder responses to storms and boulders as sedimentary signatures of storm events we identify gaps in our conceptual and quantitative understanding lastly we propose means of addressing research gaps improving consistency between researchers and collecting multi purpose data this review and the papers contained within the special issue provide an improved understanding of coastal dynamics particularly the role storms can play in influencing erosion rates and depositional patterns of coarse material i e boulders or larger which has hitherto been under represented in the literature

boulders transport by catastrophic waves along the ionian coast of apulia southern italy abstract several tracts of the ionian coast of apulia southern italy are characterized by large boulders up to 80 t in weight scattered some meters above present sea level the largest boulder is about 80 t in weight and slid for about 40 m from the mean sea level up to about 1 8 m of altitude elongated boulders show a remarkably narrow range of orientation of the long axis as well as of the imbrication axis suggesting that they had been transported by a single catastrophic event most likely a tsunami connected to a wave train approaching the coast from the south stratigraphic morphological and historical data suggest that this event occurred during the late holocene conventional radiocarbon age determination performed on lithophag shells collected from a large boulder yielded a calibrated age between 1421 and 1568 a d then the catastrophic wave train probably a tsunami could be a local effect of the strong earthquake which hit southern italy on december 5th 1456

revealing the coastal event history of the andaman islands bay of bengal during the holocene using radiocarbon and osl dating earthquakes that trigger tsunamis are of great geological ecological and socio economic importance the knowledge of the recurrence interval of these events will give information about the hazard for a region coastal sediments on the andaman islands located in the eastern bay of bengal were investigated to find evidence for palaeotsunamis and palaeoearthquakes fieldwork was conducted on red skin island and north cinque island south of south andaman sediment material from event layers was dated by optically stimulated luminescence and radiocarbon dating method the results show evidence possibly for one earthquake at about 1 000 or 3 000 years before the present together with deposits from possible tsunamis and storms the complex pattern of co and post seismic uplift and subsidence of the andaman islands is reflected in the investigated sections and made it possible to reconstruct an event history for the last 3 000 years

boulder deposits from large waves during the last interglaciation on north eleuthera island bahamas abstract seven boulders measuring 100 to 1000 m 3 are scattered along the coastal ridge of north eleuthera some are situated on ridge crests up to 20 m above present sea level the boulders were probably deposited during oxygen isotope substage 5e or 5d as shown by their stratigraphic setting and by amino acid racemization ratios d alloisoleucine l isoleucine ratios were determined for land snails and oolite of both marine and eolian origin was associated with the boulders like the boulders the probable source rocks exposed in the adjacent cliffs are composed of marine and eolian limestone of oolitic and peloidal composition the source beds are correlated with stage 9 or 11 the largest boulder is about 10 times the size of the largest holocene ones moved by waves in the area tsunamis are a reasonable possibility as a transporting mechanism of the pleistocene boulders however if deposited instead by storms during the last interglaciation the storms were of much greater intensity than those occurring in the region during the late holocene

cliff top storm deposits on banneg island brittany france effects of giant waves in the eastern atlantic ocean this study is based on the morphosedimentary analysis of the cliff top storm deposits accumulated on the coast of banneg island located in the archipelago of molene brittany france these ctsds comprise large tabular clasts quarried from the upper part of the cliff and the backing scoured platform by giant oceanic storm waves impacting directly the western coast of the island an analysis of the distribution and the geomorphology of these accumulations were carried out using the dgps topographic surveys most of the clasts are organised into imbricate boulder clusters or ridges deposited between 7 5 and 14 5 masl 52 accumulations were inventoried from the north to the south of the island representing a global volume of 1000 m3 the median size of the clasts calculated is equivalent to 0 8 0 6 0 4 m and a weight of 0 6 t the largest one measuring 5 3 3 9 0 5 m 32 t is located in the centre of the island ridge 28 it has been deposited 14 m inland from the edge of the cliff at the elevation of 9 m sediment analysis shows that clast sizes become smaller with increasing distance from the shoreline but there is no relationship between the sorting and the distance inland a study of the hydrodynamic conditions inducing clast transport was undertaken by an analysis of the wave data from the 1989 to the 1990 winter storms models of wave runup indicate that their highest water levels may have reached up to 19 masl 5 to 10 m higher than the top of the cliff submersion by giant storm waves has been more important and frequent in the centre and the south of the island wave data over the 1979 to the 2007 period shows that no events as powerful as those of the 1989 to the 1990 winter were recorded during the last 30 years yet it appears that the 1979 1990 decade was characterized by important morphogeneous events while the following period 1990 2007 has experienced a sharp decrease in storm events these variations could be attributed to the inversion from a negative towards a positive phase in the north atlantic oscillation index

geological and hydrodynamical examination of the bathyal tsunamigenic origin of miocene conglomerates in chita peninsula central japan a conglomerate appears on a rocky coast called tsubutega ura coast located on the southwestern coast near the southern tip of the chita peninsula aichi prefecture central japan the conglomerate belongs to miocene sedimentary rocks termed the morozaki group the conglomerate includes meter scale boulders indicating that it was formed by an extraordinary event in the geological investigation we observed that the conglomerate shows alternate changes of paleocurrent directions between seaward and landward this feature is supposed to be formed by tsunami currents in the hydrodynamical investigation we obtained following results 1 the lowest limit of a current velocity to move a boulder of about 3 m in diameter would be about 2 3 m s 2 the speed of tsunami currents reproduced by tsunami simulation exceeds 3 m s at 300 m in depth when the tsunami is generated by a gigantic earthquake with magnitude 9 0 or more 3 the transport distance of the boulder would be several hundred meters to several kilometers by one tsunami event caused by a gigantic earthquake we conclude that tsunamis best explain the formation of the conglomerate deposited in upper bathyal environments about 200 400 m depth both from geological and hydrodynamical viewpoints

reply to comments by kelletat 2008 comments to dawson a g and stewart i 2007 tsunami deposits in the geological record sedimentary geology 200 166 183

characteristics and hydrodynamics of boulders transported by storm waves at kudaka island japan abstract this study investigates the size position and the long axis orientation of 210 boulders at kudaka island japan these boulders were deposited from the reef crest to the slope of the back reef moat distributed within 275 m from the reef edge most boulders were rectangular to ellipsoidal without sharp broken edges they are reef rock fragments estimated as

cliff top megaclast deposits of ireland a record of extreme waves in the north atlantic storms or tsunamis past occurrences of major tsunami in the global record have often been inferred from the presence of megaclast accumulations at significant heights above sea level which sometimes exhibit a pronounced seaward directed imbricate fabric the aran islands off the west coast of ireland exist in a marine environment which is totally unprotected from the most extreme sea states encountered in the north atlantic spectacular megaclast accumulations are found along the tops of vertical cliffs on these islands the elevation of these deposits varies from 0 m to 50 m above mean sea level and they include clasts weighing 250 tonnes at sea level over 117 tonnes at 12 m and 2 9 tonnes at 50 m above sea level imbrication measurements on these megaclasts indicate a well defined and consistent mean direction from the southwest for the emplacing waves one that is consistent with the prevalent storm wind direction for the area the megaclast accumulations are subject to episodic and on going erosion by cliff retreat but the existing accumulations are estimated to record events since at least 1839 recent emplacement and reworking is evidenced by trapped plastic detritus within the deposits and eyewitness accounts of large storms during which clasts have been emplaced similar deposits are found on the exposed coasts of the shetland and orkney islands off scotland there is at present no evidence of any tsunami in recorded history affecting the western irish and scottish coasts other than those generated by the lisbon earthquake of 1755 where the wave effects were slight thus the presence of megaclast accumulations at significant heights above sea level on exposed coasts and exhibiting imbrication should not be used as a definitive criterion for the past occurrence of tsunami these deposits attest to extreme wave conditions occasionally encountered in the north atlantic and act as a record of such events extending back at least 160 years such data on extreme wave conditions are essential for the prediction of the effects of deepwater waves on structures such as offshore drilling platforms

comments to dawson a g and stewart i 2007 tsunami deposits in the geological record sedimentary geology 200 166 183

extremely high energy wave deposits inside the great barrier reef australia determining the cause tsunami or tropical cyclone abstract a hydrodynamic approach is used to determine whether tsunami or cyclone generated waves were responsible for the deposition of fields of well imbricated rock boulders up to 290 tonnes along the coast of cairns inside the great barrier reef australia calculations of the overturning moments show that only tsunami are capable of moving such large boulders in this environment it is hypothesised that large tsunami 11 m have been able to penetrate the great barrier reef through wide 5 10 km 50 70 m deep passages between individual reefs three such passages each approximately 35 km apart and oriented in the same direction exist in the cairns region it is possible that these passages have funnelled and amplified palaeotsunamis the preferential location of eroded coral boulders up to 3 m in length on reef flats alongside these passages and their absence on other reefs throughout the region provide further evidence that extremely high energy waves have been able to penetrate the great barrier reef into the inner channel adjacent to the mainland carbon 14 ages of the coral boulders on these reef flats matches closely the ages of coral fragments pinned below the very large rock boulders along the coast these ages suggest that the cairns region has experienced large tsunami twice over the last millennium

a quasi experimental setting of coarse clast transport by the 2010 chile tsunami bucalemu central chile abstract on 27th february 2010 a mw 8 8 earthquake occurred in central chile causing a tsunami that severely affected the central chilean coast in this study we present sedimentological data of the 2010 chile tsunami from the coastal town of bucalemu in central chile the tsunami deposited both fine grained sediments as well as cobbles and boulders the location offers a quasi experimental setting for coarse clast transport because an artificial pile of cobbles and boulders was piled there for construction purposes some days before the tsunami therefore the pre tsunami transport setting and transport distances are well defined additionally a local flow depth of ca 2 m and flow speed of ca 5 6 m s are deduced from eyewitness reports and video recordings the cobbles and boulders have been transported up to 155 m from the pile in landward direction the size of the quarried clasts was restricted to max 0 3 m3 and 720 kg bigger boulders were not available at the location even though calculations show that the tsunami would have been capable to transport them calculations of flow speeds required for the initialization of transport in different modes such as sliding rolling or saltation indicate that all clasts that were moved by the tsunami in landward direction were entrained by the flow given a minimum observed speed of 5 6 m s with 65 being transported by rolling and 35 by saltation the transported clasts are arranged in three groups positioned in morphological depressions on the coastal plain a landward fining trend is not present the arrangement of clasts originating from a pile and being deposited in distinctive groups entails that the landward transport of cobbles and boulders is a function of repeated entrainment transport and deposition by several waves of the tsunami wave train consequently we interpret the clast distribution as a result of a combination of the number of individual waves of the tsunami wave train their respective energies the local topography and the pre transport setting of a clast pile which releases wedged clasts with each successive wave

the holocene paleo tsunami history of west australia abstract west australian coastlines experienced several tsunamis in mid holocene times to expand our knowledge about holocene tsunami events in west australia the authors extended the previously studied spatial scale to include the central and south western coastlines several of the discovered events were mid and young holocene 1000 yr bp tsunami impacts on the outer coast of the cape range peninsula five hundred kilometres to the south between cape cuvier and point quobba additional tsunami evidence exists on top of steep cliffs over a coastal stretch of 30 km the sedimentary signature of two tsunamis is documented in this area by wide ridges comprised of sand shell and clasts including coral fragments at heights of 12 30 m asl and 300 500 m inland enigmatic boulders 20 100 tons appear as cliff top megaclasts up to 100 m inland here radiocarbon dating revealed a minimum of two tsunami events at 5700 yr bp with waves depositing sandy ridges far inland and at approximately 1000 yr bp with waves depositing boulders originating from the marine environment as the first dates are congruent with previously published results for the learmonth region 500 km to the north we assume that the same mid holocene tsunami hits this long coastal section as well the southwestern coast of west australia from cape naturaliste to albany also shows signs of impacts by extreme waves here huge granite boulders 80 400 tons were dislocated and transported to heights up to 10 m above sea level the most prominent dislocated boulders were positioned at merchant rock cape naturaliste national park at islet near nanarup and in cave bay close to albany

numerical models of tsunami sediment transport current understanding and future directions abstract researchers who study tsunami deposits share common ultimate goals of their work which are to better assess the magnitude information of paleotsunamis and to contribute to the assessment of future tsunami risks numerical modeling of tsunami sediment transport is an important piece of interdisciplinary research that fills the gap between geological studies and practical utilization of tsunami deposits forward and inverse numerical models that address tsunami transport of sand and boulders have been developed over the last two decades forward models are capable of delineating the time evolution of tsunami hydrodynamics sediment transport and the resulting morphological changes associated with erosion and deposition inverse models estimate tsunami characteristics such as flow speed and depth from deposits numerical modeling can be used not only to quantify paleotsunamis but also to enhance our understanding of tsunami sedimentology and hydrodynamics to make progress towards the ultimate goal of improved tsunami risk assessment development of an in depth mutual understanding between modelers and geologists of the advantages limitations and uncertainties in both numerical modeling and geological records is an important challenge

vadose zone recharge and weathering in an eocene sand deposit east texas u s a abstract weathering of terrigenous sand in the vadose zone of the eocene calvert bluff formation in freestone county texas appears to be controlled by vadose water flow rate and kinetics of dissolution and precipitation of silicate minerals feldspar grains more commonly appear corroded by surface reaction controlled dissolution than argillized in situ kaolinite and smectite which most likely precipitated from silica rich vadose water coat remaining framework grains where those grains are later dissolved delicate clay molds remain the relative abundances of feldspar and clay minerals are inversely related and vary with depth reflecting the cumulative effect of feldspar weathering concentrations of dissolved and adsorbed cations generally are near massaction equilibrium recharge occurs from march to may spring and from october to november autumn when there is a net excess of water in the vadose zone dissolved ionic concentrations fluctuate seasonally with vadose water residence time suggesting that mass flux is close to mineral dissolution rate

the role of porosity in discriminating between tsunami and hurricane emplacement of boulders a case study from the lesser antilles southern caribbean coastal boulder deposits are a consequence of high energy wave impacts such as storms hurricanes or tsunami parameters useful for distinguishing between hurricane and tsunami origins include distance of a deposit from the coast boulder weight and inferred wave height in order to investigate the role of porosity on boulder transport and elucidate the distinction between tsunami and hurricane impacts we performed archimedean and optical 3d profilometry measurements for the determination of accurate physical parameters for porous reef and coral limestone boulders from the islands of aruba bonaire and curacao abc islands netherlands antilles leeward islands subsets of different coral species and lithotypes constituting the boulders were sampled the physical parameters of boulders were analyzed and each boulder component was attributed to a certain range of porosity and density lowest porosities were observed in calcarenite 5 8 whereas highest porosities were measured for serpulid reef rock 47 68 porous serpulid reef rock 0 8 1 2 g cm 3 and the coral diploria sp 0 6 1 0 g cm 3 possess the lowest bulk densities while less porous calcarenite 2 0 2 7 g cm 3 and the coral montastrea cavernosa yield the highest bulk density values 1 6 2 7 g cm 3 the obtained physical parameters were used to calculate boulder weights and both hurricane and tsunami wave heights necessary to initiate transport of these boulders boulders are up to 5 6 times lighter than given in previously published data and hence required minimum hurricane or tsunami waves are lower than hitherto assumed the calculated wave heights the high frequency of tropical storms and hurricanes in the southern caribbean and the occurrence of boulders exclusively on the windward sides of the islands implicate that for boulders on the abc islands a hurricane origin is more likely than a tsunami origin 2008 elsevier b v all rights reserved

boulder emplacement on a tectonically stable wave dominated coastline mission rocks northern kwazulu natal south africa abstract the presence of large boulders along rocky coastlines is a useful indicator as to the occurrence and nature of past storms and or tsunami field observations from mission rocks northern kwazulu natal south africa allowed for the assessment of historical high magnitude wave events in the area a total of 143 anomalously large boulders were assessed in terms of their dimensions morphologies and distribution along a regionally developed 3 m raised shore platform based on long intermediate and short axes relationships we calculate boulder masses of up to 9 03 t that were found to have been transported horizontally shoreward for up to 65 m based on geomorphological evidence we infer that the majority of boulders encountered were from a joint bound pre transport setting additionally overturning of the boulders was apparent we assess the boulder field numerically via the numerical model of pignatelli et al 2009 which we deemed most applicable for slab like boulders such as those encountered here results yielded a maximum breaking storm wave height of 11 36 m or a maximum tsunami height of 2 84 m an analysis of swell data revealed that the modelled storm wave heights fell within the range defined by the storm wave records for the area within the past 32 years boulder alignments were likewise compatible with the wave regime of the northern kwazulu natal coastline additional review of offshore seismic records and landslide hazards on the tectonically stable passive margin show that the tsunami hazard for landslides within the area is negligible the findings suggest a storm provenance as the causal mechanism for boulder emplacement at mission rocks

stable imbrication and delicate unstable settings in coastal boulder deposits indicators for tsunami dislocation abstract medium sized and coarse debris pebbles and boulders can exhibit patterns of setting particularly if they are elongated or tabular these patterns such as imbrication indicate certain transport processes mostly as to direction and character many years of observation and measuring of coarse coastal deposits are the basis for the conclusions presented here on environmental transport processes their character and their energy beside imbrication special emphasis is given to unstable or delicate settings of large boulders that evidently have remained in these positions from hundreds to thousands of years this deserves an explanation to how they arrived at these positions and why they have not changed into a more stable position given an environment of constant energy input along coastlines the discussion lays emphasis on whether both settings of mega boulders can be indicative of tsunami transport processes

testing the hypothesis for tsunami boulder deposition from suspension tsunamis are known to deposit boulders but it is not clear if they are transported solely as bed load or whether suspended load can be involved it has been reported that numerous individual boulders and imbricated boulder stacks at elevations above normal storm tide levels along the new south wales nsw coast of se australia have been deposited out of suspension by tsunamis the nsw coast therefore provides an important natural laboratory to test the hypothesis that tsunamis can deposit large boulders from suspension using standard hydrodynamic equations to formulate the relationship between boulder transport and flow depth we provide a test of the suspension hypothesis we show that the tsunami flow depths required for deposition from suspension are most probably physically unrealistic the nsw boulders are therefore not indicative of deposition from suspension and an alternative explanation must be sought for their mechanism of emplacement this analysis has important implications for the emerging sub branch of tsunami boulder geology

clast mobility within boulder beaches over two winters in galicia northwestern spain abstract a micro drone was used to make low altitude flights over boulder beaches at laxe brava and oia in galicia northwestern spain flights were made in july 2012 may 2013 and spring 2014 high resolution digital terrain models and orthophotographs combined with gis mapping were used to monitor changes in the position of thousands of boulders maximum storm wave height was higher in the winter of 2013 2014 than in winter 2012 2013 and this was reflected in an increase in the proportion of the boulders that moved in the two winters from 17 to almost 48 at laxe brava and from 53 to almost 88 at oia the greater mobility of the boulders at oia can be attributed in part to their generally smaller size although there was considerable overlap between the size of boulders that moved and those that did not move within and between the two beaches there were mobile boulders in areas up to several metres above the high tidal level on both beaches and boulder transport in the shore normal and alongshore directions triggered some changes in the beach profiles particularly in the middle to upper parts of the beaches estimates of threshold transport conditions scaled to boulder mass breaker height and other variables suggested that all but the very largest boulders on the two beaches should have been mobile even during the summer months when the waves were much lower than in winter model over prediction can be attributed to a number of factors including constraints on movement imposed by surrounding boulders differences in boulder size and their effect on pivoting angles and on the degree to which boulders are exposed or sheltered from wave impact and difficulties in assigning appropriate values to model coefficients

boulder transport by waterspouts an example from aorangi island new zealand abstract in 1996 the vegetation on aorangi island within the poor knights island nature reserve new zealand was found to be severely damaged the damaged zone consisted of a distinct trail of stripped soil and broken vegetation starting at sea level and travelling in an arc across the northeastern flank of the island cobbles encrusted with marine life sea urchins and seaweeds were deposited at elevations up to 45 m above sea level along and beside the damaged zone boulders up to 2 m in size were transported horizontally at elevations of 5 15 m above sea level and larger boulders were destabilised at 25 m above sea level causing them to slide and roll downslope application of threshold entrainment relationships for tsunamis storm waves and waterspouts indicates that a waterspout is the most probable mechanism for the observed damage and transport of large clasts the addition of 2 5 5 of atomised water to the waterspout vortex significantly increases the flow competence hence intensity t3 t5 torro tornado intensity scale or f2 fujita tornado intensity scale waterspouts commonly observed around the new zealand coast are capable of moving boulders up to 2 m in size

late holocene sea levels in ireland the course of irish sea levels during the late holocene is not well known yet it is an understanding of this period that will prove crucial in the definition and management of future sea level changes the coastline of ireland embraces wide environmental and glacio isostatic contrasts which serve and to some extent control sea level events at both local and regional scales making definitive resolution of relative sea level changes difficult in the southwest the picture is of inexorable relative sea level rise studies in co kerry show a gradual submergence of terrestrial facies by estuarine and in places marine materials pollen and diatom studies together with 14c dates suggest a decreasing rate of relative sea level rise in the last 2500 years often associated with geomorphological changes sites on the south coast of ireland confirm the evidence from the southwest in cork harbour recent relative sea level rise since 2100 bp was responsible for marginal land submergence while elsewhere rising water levels appear to have caused rapid barrier migrations and coast erosion palaeoenvironmental evidence from this region suggests a distinctive pattern of sea level change associated with sedimentary and or crustal dynamics which is not encountered elsewhere in northwest europe the overall rate of relative sea level change on the south and southwest coasts falls between 0 6 and 1 1 mm year over the last 5000 years in the north there is a clear east to west variation in relative sea level trends following an isostatically controlled peak 3 to 1 m od between 6500 bp east and 3500 bp west falling sea levels from 3500 to 1500 bp have been followed by a general slow rise although there are still local anomalies to this pattern most noticeably at malin head where sea level is currently falling at 2 4mm year relative sea level signatures in ireland differ markedly between the north and south coasts furthermore geomorphological and ecological contexts of this rise vary from east to west providing a complex all ireland framework for future investigations

tsunami deposits and recurrence on a typhoon prone coast of northern taiwan from the last millennium abstract widely known for its hazardous history taiwan holds valuable records of nw pacific tsunamis and typhoons despite the similarity between tsunami and typhoon deposits historical accounts enabled the identification of the 1867 tsunami deposit on the northern coast through matching with the record setting inundation however the identification of prehistoric tsunami deposits has been hindered by severe sediment reworking and post depositional changes produced by the typhoon prone tropical and humid climate in this study we investigated the upper holocene facies and their sediment sources and radiocarbon ages on distal floodplains and rocky backshores of the northern coast where sediment reworking is less intense four decimetre thick gravelly layers were identified intercalated with fluvial mud and colluvium the gravelly layers are composed of beach derived quartz rich sand and rounded gravels of the sedimentary basement rocks longshore drift andesite and stranded pumice the remarkable layer thickness gravel size and quartz richness were determined to have endured post depositional changes the event layers are sharp based matrix supported and poorly sorted and have recorded scouring sediment entrainment and rapid fallout of suspension rich turbulent flows that probably originated with tsunamis the event layers occur 0 5 0 8 km inland and 3 11 5 m above sea level matching the 1867 tsunami inundation and wave height respectively radiocarbon dating tied the event layers to the 1867 tsunami and three prehistoric events that occurred in the periods 1545 to 1810 1293 to 1414 and 1090 to 1235 representing a recurrence interval of 83 436 years over the last millennium

megaclasts proposed revised nomenclature at the coarse end of the udden wentworth grain size scale for sedimentary particles abstract the expanded udden wentworth u w grain size scale is an important tool for classifying the size of sedimentary particles however some of the existing terminology at the coarse end of the scale is problematic in particular the current terms block and slab are used to define size ranges despite having recognized shape connotations and simultaneous application in particle form shape diagrams the dual usage such of terminology is undesirable and may have contributed to the lack of strict adherence by the earth science community to the upper end of the u w scale resulting in part in the plethora of alternative expressions that have appeared in recent years for describing very large clasts our solution to this conundrum is to abandon shape related terms and replace them with an incremental system based on the prefixes meso and macro to classify very large boulder size ranges in this way both size and shape classification of very coarse sediments can be accomplished satisfactorily without unnecessary overlap or confusion in nomenclature the term megaclast is appropriate to remain as a universal descriptor for all clasts greater than boulder size i e b axis 4 1 m as previously defined

extreme block and boulder transport along a cliffed coastline calicoan island philippines during super typhoon haiyan abstract this paper presents data and analysis for block and boulder transport during super typhoon haiyan along a 4 5 km long low 5 12 m cliffed coastline in calicoan island eastern samar philippines wave runup exceeding 15 2 m elevation above mean sea level drove large limestone clasts with volumes up to 83 m3 up to 280 m inland a few very large clasts with volumes 65 132 m3 were not transported by the waves when combined with recent transport reported in may et al 2015 cox et al 2016 and other literature it is becoming increasingly clear that the largest blocks transported by storms overlie much of the tsunami transport range increasing the difficulty in attributing the transport source without additional evidence comparison of present results with a global database of storm boulder transport shows a mass elevation envelope outside of which no transport is observed initiation of motion criteria were extended to include non rectangular cross sections which significantly reduces inferred velocities particularly for overturning motion these new relations were applied to the largest observed sliding and overturning boulders while considering coefficient uncertainties and resulting velocity uncertainty was large enough that direct inference of wave heights would be problematic estimates of initiation velocities for cliff edge boulders computed using lifting joint bounded relations were unreasonably large when compared to those for sliding and overturning boulders suggesting that processes other than bernoulli lift forces dominated at cliff edges

testing the numerical models for boulder transport through high energy marine wave event an example from southern saurashtra western india abstract presence of large boulders along rocky coasts can be used as archives to reconstruct past extreme wave event history vital for the coastal hazard assessment dimensions of boulders lying in supratidal zone have been used to reconstruct the origin of wave responsible for their transport and processes there are several mathematical equations available which take into account submerged subaerial and joint bounded block scenarios for boulder transport to estimate the wave height required to transport the boulders to their final position however there are limited studies which validate these equations using modeling and observational analysis navabandar coast situated in western india provides an excellent opportunity for such analysis as there exists three boulders derived from shore platform during the november 1982 storm we present the analysis of these boulders and event history of region to conclude that all the mathematical equations overestimate the wave heights required to dislodge and transport these boulders by at least 5 times the actual event we emphasize that there is a vital need to re evaluate and improve the existing equations considering the local control variables for better visualization of palaeo tsunami storm events

magnitude and frequency of extra tropical north atlantic cyclones a chronology from cliff top storm deposits cliff top storm deposits ctsds are known to occur on cliffs at elevations of up to 50 m above sea level at exposed sites on the deep water coasts of the british isles eye witness accounts and time series field mapping of ctsds demonstrate their formation over the historical period and their continued modification during major storms with ctsds burying a range of modern human derived debris older deposits show surface lichen growth and weathering effects that relate to the relative age of ctsds over longer time spans buried sand and peat deposits provide dates on phases of ctsd emplacement and mobilisation and so provide an indication of the frequency and timing of the most severe storms two adjacent sites in shetland provide a combination of 14c dates on peat buried beneath storm deposited boulders 14c dates on marine shells buried inside ctsd boulder ridges and optically stimulated luminescence osl ages on sands intercalated with storm derived boulders although the precision is low this evidence identifies phases of exceptional storm activity spanning approximately 400 550 700 1050 1300 1900 and since 1950 ad by the very nature of cliff top erosion and deposition these records are fragmentary yet the timeline of major storms recorded in the shetland cliffs matches fairly well with the more general record of storminess in the north atlantic derived from the sea salt record in the gisp2 ice core as such ctsds represent an overlooked archive of storm sedimentation with the potential to elucidate local storm chronologies as well as informing debate surrounding the palaeo tempestology and impact of major cyclones and hurricanes

quaternary deposits and glacial stratigraphy in ireland quaternary stratigraphic studies in ireland have been based largely on lithostratigraphy the division of complex sedimentary sequences into the traditional framework of munsterian and midlandian events has created a series of stratigraphic scenarios which cannot be fully substantiated either by biostratigraphy or by facies basin analysis many of the current problems of glacial stratigraphy in ireland therefore arise directly from the field procedures used and the frameworks used to subdivide sedimentary sequences these problems are centred on the selection of type sites the subdivision of sedimentary sequences into unnatural divisions the concepts of direct and indirect stratigraphy classical models of climatically determined ice advance retreat cycles and the genetic inferences of the term till the conceptual basis of various stratigraphic schemes has changed little since the work of farrington 1934 1966 it is argued that a more realistic approach to description and assessment of glacigenic sediments should be based on basinal facies analysis and must include a documentation of the composition and geometry of three dimensional facies variations palaeoenvironmental interpretations of complex glacigenic sequences especially in coastal locations should take account of the influences of marine ice sheets on the sedimentary record in the past most sequences were interpreted in terms of glacioterrestrial models a large body of sedimentary evidence now indicates that shallow glaciomarine environments occurred along the margins of the last ice sheet during its maximum and subsequent retreat phases the locations and patterns of associated icemarginal systems indicate that the magnitude of and patterns of crustal deformation were greater and more complex than formerly realised thus the primary control on sea level variation at successive ice sheet margins was largely a function of glacioisostatic disequilibrium although complex glacial and glacially related sequences are known it is argued here that most of the multiple glacigenic sequences in ireland can be accommodated within the midlandian cold stage the basal units from certain sequences and erratic fans have been attributed to events earlier than the midlandian however it is difficult to compare these traces of earlier events from different sectors of the island due to poor dating correlation and the fact that direct and indirect stratigraphy is not adequately defined or separated the age of the gortian style interglacial sequences the implications of their floristic composition and their relationships to drift stratigraphy remains a major problem in stratigraphic constructions of the irish quaternary the stratigraphic significance of many till units must remain largely unknown until these matters are resolved at present it is not clear if the gortian sequences represent more than one interglacial a series of exposures in ulster provide evidence for major environmental changes during the midlandian cold stage these include an early stadial an early forest biozone 48 1 ka bp an early herb biozone 41 5 ka bp a middle interstadial phase of cold but non glacial aspect 30 5 ka bp a late stadial max 24 22 ka bp and a late glacial climatic oscillation the late midlandian stadial comprises a major glaciation that almost covered the island and a later more restricted phase when drumlins formed in the northern and western parts of the island max 17 ka bp

giant boulders and last interglacial storm intensity in the north atlantic as global climate warms and sea level rises coastal areas will be subject to more frequent extreme flooding and hurricanes geologic evidence for extreme coastal storms during past warm periods has the potential to provide fundamental insights into their future intensity recent studies argue that during the last interglacial mis 5e 128 116 ka tropical and extratropical north atlantic cyclones may have been more intense than at present and may have produced waves larger than those observed historically such strong swells are inferred to have created a number of geologic features that can be observed today along the coastlines of bermuda and the bahamas in this paper we investigate the most iconic among these features massive boulders atop a cliff in north eleuthera bahamas we combine geologic field surveys wave models and boulder transport equations to test the hypothesis that such boulders must have been emplaced by storms of greater than historical intensity by contrast our results suggest that with the higher relative sea level rsl estimated for the bahamas during mis 5e boulders of this size could have been transported by waves generated by storms of historical intensity thus while the megaboulders of eleuthera cannot be used as geologic proof for past superstorms they do show that with rising sea levels cliffs and coastal barriers will be subject to significantly greater erosional energy even without changes in storm intensity

wave emplaced coarse debris and megaclasts in ireland and scotland boulder transport in a high energy littoral environment abstract many coastlines of the world particularly those at higher latitudes and those located in tropical cyclone belts are regularly battered by strong storm waves drowning of low lying areas by storm surges and storm floods has been thoroughly recorded however storm deposits at rocky shorelines or on cliffs have been underrepresented in the literature this article presents observations of extraordinary wave deposits along the high wave energy coastlines of western ireland and the northern scottish isles and discusses possible wave event types and time windows of the processes responsible we used archaeological geomorphological and geochronological disciplines to compare our findings with earlier results published for these areas and to contribute to the debate on whether large clasts found well above sea level and or a considerable distance inland were deposited by storms or by tsunamis

competing mechanisms for boulder deposition on the southeast australian coast this study investigates the role of late holocene sea level change large storms and possible pre historic tsunami in the deposition of boulder features on an exposed headland and sheltered rock ramp large accumulations of boulders are found on coastal rock platforms cliff tops and ramps in the jervis bay region of southeastern australia these deposits are elevated above sea level and in places exhibit obvious signs of imbrication as a response to flow in a landward direction the event history of these features is controversial and holocene sea level change storms and tsunami can be considered as possible non mutually exclusive mechanisms of deposition it is apparent that even if the detachment site transport distance elevation and final orientation of a boulder can be identified deciphering the event history remains a difficult task

from fine sand to boulders examining the relationship between beach face slope and sediment size abstract it is a long standing maxim that coarser sediment sizes are associated with steeper beach face slopes but because most work has focused on sandy beaches few data are available for the pebble cobble or boulder size ranges little is known therefore about how beach morphology and grain size relate at the coarser size grades we compiled data from the literature 2144 measurements of beach face slope with associated grain sizes covering the range from very fine sand to boulders this meta analysis shows that beach faces do tend to steepen as average grain size increases at least up to the cobble size range but the trend is not simple although previous studies suggested a simple power law relationship between grain size and beach face slope in fact the data distribution is best fit by a curve that is steep at the finer grain sizes but is much more gentle as grain size coarsens and may trend downward for boulders fine and medium sands have the greatest range of reported slopes and the data support the importance of effective weight modification and boundary layer dynamics as primary controls on beach face steepness at these fine size grades around the very coarse sand size grade a plateau marks a shift in beach dynamics as hydraulic conductivity increases beaches switch to being infiltration dominated the trend toward steeper slopes continues but at a lower and steady rate from granules through cobbles there appears to be a falloff in slope for the coarsest boulder deposits but we note that this is based on very few locations so should be considered preliminary the overall data distribution is described by a power law function tan a d 50 0 125 b c the broadness of each transition zone also shows that a range of factors other than grain size governs where that tipping point occurs in the cobble and boulder size ranges there are two deposit categories boulder beaches and supratidal boulder ridges although not commonly thought of as beaches boulder ridges record long term storm deposition and reworking on the highest energy coasts supratidal ridges and boulder beaches seem to show different slope grain size relationships with the steepest slopes occurring in boulder ridges and with boulder beaches showing more gentle gradients than other coarse clastic beaches but our data set reveals how little quantitative information exists about the coarsest end of the beach spectrum and invites further work to investigate the sedimentology of cobble and boulder dominated systems

wave emplaced coarse debris and megaclasts in ireland and scotland boulder transport in a high energy littoral environment a discussion scheffers et al 2009 describe a reconnaissance survey of boulder accumulations along parts of the atlantic coasts of the british isles a substantial part of their report concerns the characteristics of wave transported boulder deposits found high above sea level on cliffs these boulder deposits reach perhaps their ultimate development along the coasts of the aran islands galway bay western ireland and eshaness shetland northern scotland where evidence of wave action reaches elevations of 50 m above sea level a s l we have previously investigated in detail these and numerous other similar localities and concluded that the boulder deposits are cliff top storm deposits ctsds part of an assemblage of features found on certain cliffs on these very high energy coasts that relate to the impacts of extreme waves during major storms williams and hall 2004 hall et al 2006 2008 hansom et al 2008 hansom and hall 2009 however scheffers et al 2009 p 571 claim that at these and other sites no evidence exists for storm wave dislocation of boulders found at altitudes of 120 m a s l indeed no calculations of possible storm wave heights storm wave physics or ages of the deposits and no descriptions of extraordinary storms are sufficient to explain these displacements p 568 and alternative explanations such as tsunamis should be considered p 571 here we rebut these claims by briefly restat

in situ exhumation from bedrock of large rounded boulders at the giant s causeway northern ireland an alternative genesis for large shore boulders mega clasts abstract very large boulders mega clasts are found on some coasts the size and position of the boulders has been used to suggest that contemporary marine processes acting within their normal spatial and energy range are unlikely to have moved them explanations for the presence of such boulders include transport by infrequent very high energy marine processes storms or tsunamis mass movement from backing cliffs transport by ice or exhumation from glacial deposits this paper advances an alternative explanation which does not involve transport by any of the marine or glacial processes or gravity it is proposed that in a very specific geological and topographic setting large boulders are exhumed in situ by storm waves acting on heavily weathered jointed basalts eventually wave action liberates residual blocks from the deeply weathered matrix these liberated boulders will be mobile only if they lie within wave competence and the larger ones will remain as stationary residuals the same in situ weathering processes followed by removal of the friable matrix material debris by wave action also progressively round the boulders consequently despite their appearance of being transport rounded the larger boulders have not transported at all in specific locations the assumption that the presence and rounding of such large clasts in the shore zone can be attributed to marine transport can lead to erroneous interpretations of very high energy storm wave or tsunami activity

advantages of beachrock slabs for interpreting high energy wave transport evidence from ludao island in south eastern taiwan abstract powerful typhoons frequently affect eastern taiwan on dabaisha beach on the sw coast of ludao island a small volcanic island lying se off mainland taiwan the presence of numerous beachrock slabs provides evidence of the sediment transport capabilities of high energy waves generated by these storms with a well defined beachrock source from which the slabs were derived it is easy to differentiate clasts transported in run up or backwash flow based on their current position relative to the outcrop in order to estimate the wave generated flow velocities from the measured beachrock slabs the hydrodynamic equations for boulder transport by nandasena et al 2011 have been rearranged so that they are appropriate for this particular geomorphic setting where exposed in situ beachrock outcrops liberate clasts which may then be transported either by run up onto the beach or backwash flow onto adjacent reef platforms such settings are common on tropical coastlines with fringing coral reefs and beaches comprising mostly biogenic sediments in the dabaisha beach case the lowest flow velocities required to transport all measured beachrock slabs from their source outcrop to current positions are 2 18 3 16 m s for run up and 1 76 3 24 m s for backwash with a discussion of advantages and limitations on the use of beachrock clasts for interpreting wave behaviour this paper presents another proxy for studying high energy wave events that is highly suitable for certain carbonate rich coastlines

late holocene storm imprint in a coastal sedimentary sequence northwest iberian coast a combination of sedimentological geomorphological and pedological methods has been used to study a late holocene sedimentary sequence in a rock coast sector from nw spain with the aim of relating it to storm events and their morphodynamic effects the sequence contains two coarse beach layers at an elevation of 2 8 3 5 m above the present highest astronomical tide hat radiocarbon dating revealed that their deposition had begun during 1735 1590 cal yr bp and has continued until the present the entire beach system experienced considerable morphological change after 1320 1230 cal yr bp with a westward displacement of the beach and a retreat of the sedimentary cliff in the eastern section the two beach layers seem to have been formed by vertical aggradation of clasts and sand during high energy storm events highlighting the role of these events in the formation of sedimentary sequences on the rocky coasts of mid atlantic europe the effects of a recent storm event recorded in march 2008 and the

storm rogue wave or tsunami origin for megaclast deposits in western ireland and north island new zealand the origins of boulderite deposits are investigated with reference to the present day foreshore of annagh head nw ireland and the lower miocene matheson formation new zealand to resolve disputes on their origin and to contrast and compare the deposits of tsunamis and storms field data indicate that the matheson formation which contains boulders in excess of 140 tonnes was produced by a 12 to 13 m high tsunami with a period in the order of 1 h the origin of the boulders at annagh head which exceed 50 tonnes is disputed we combine oceanographic historical and field data to argue that this is a cliff top storm deposit ctsd a numerical model for ctsds is developed which indicates that boulder shape in addition to density and dimensions should be taken into account when applying hydrodynamic equations to such deposits the model also predicts that the ne atlantic storms are capable of producing boulderites that when size alone is considered cannot be distinguished from tsunamites we review the characteristics that identify the origins of these two deposits

waves coastal boulder deposits and the importance of the pre transport setting the pre transport environment of a coastal boulder along with its shape size and density determines the height of wave required for it to be transported different forces act on sub aerial boulders as opposed to submerged boulders when struck by a wave boulders derived from joint bounded blocks on shore platforms predominantly experience lift force and require a wave of greater height to be transported than boulders in other environments no one equation is applicable to determine the height of palaeo waves responsible for depositing a field or ridge of imbricated coastal boulders a range of equations and their derivation is presented here which can be applied to the respective pre transport environment of a boulder such an approach is necessary when attempting to reconstruct the frequency and magnitude of past coastal wave hazards and for differentiating between tsunami and storm wave deposited boulder fields

global to local scale parameters determining relative sea level changes and the post glacial isostatic adjustment of great britain abstract observations of relative sea level rsl change in great britain since 16 kyr bp and models of post glacial isostatic adjustment provide constraints on reconstructions of the british and antarctic ice sheets from the last glacial maximum to the present we use the global model from an earlier investigation modified ice 4g vm2 with lithospheric thickness 90 km which gives good rsl fits globally as well as for much of the british data a revised ice model for great britain that fits with recently published observations on ice limits and heights fails to explain all the misfits between rsl observations and predictions much more significant improvements result from models that incorporate a different chronology for the partial deglaciation of antarctica while keeping the total ice melt 17 m the same as in ice 4g vm2 the results suggest antarctic melting of 3 m ice equivalent sea level by 15 kyr bp only 1 m contribution to the 24 m rise of mwp1a with the major melting 12 5 kyr bp and a small amount of melting 1 0 0 3 m between then and 3 or 2 kyr bp these modifications produce rsl predictions for barbados that show the major changes in rate of sea level rise but with an offset up to 1 kyr compared to the observations possible explanations that remain to be investigated further are a delay in the melting of ice from some other region a reduction in the total melt derived from antarctica and a refinement of the 1 kyr temporal resolution assumed in the construction of the theoretical solution

a wave competence approach to distinguish between boulder and megaclast deposits due to storm waves versus tsunamis abstract size and mass of boulders and megaclast deposited from intense wave events of the past coupled with measures of depositional elevation and transport distance are useful metrics to distinguish between tsunami or storm wave period this outcome provides for a wave competence scaling approach to better help distinguish between large storms and tsunamis because wave period for tsunamis and wind driven storm waves differ by an order of magnitude however wave competence equations are simple linear approximations of a complex non linear processes hence interpretations of the results need to be taken carefully at best they may help approximate wave forcing based on size of material transported coupled with other pieces of information gained from stratigraphy imbrications and morphology of boulder and megaclast deposits as well as aging techniques for temporal correlation with known storms and or tsunamis the focus here is to present a conceptual example of how to apply a wave competence approach to a beach exposed to both tsunamis and major storm waves and how variance in backshore topography hills and valleys and source material sea cliff erosion and scree slope development may play into interpreting the mathematical results

sedimentology of rocky shorelines 2 shoreline megaclasts on the north shore of oahu hawaii origins and history abstract limestone megaclasts up to 96 t in weight rest on a coastal rock platform near sunset beach on the north shore of oahu hawaii they occur in seaward dipping imbricate clusters and as solitary clasts the rock platform is subject to large swell waves and very large waves associated with winter storms and tsunami a series of photographs covering the period from ca 1905 to 1996 show episodic rearrangement of megaclasts on the platform and the appearance of new megaclasts near the platform edge the largest solitary megaclast ca 96 t was emplaced on the platform between 1940 and 1950 possibly by the 1946 aleutian tsunami and has moved twice since then in ca 30 m jumps along two different trajectories larger clasts have been broken from the platform edge and emplaced on the platform only by very large wave events whereas formation and movement of smaller tabular clasts ca 30 40 t appear to be a continuously ongoing process on the surface of the rock platform partial detachment of clasts by marine erosion processes along joints and cracks in the limestone bedrock facilitates their complete detachment from both the platform edge and platform surface the larger numbers of megaclasts emplaced on the north and northwest sectors of the platform relative to other sectors are attributed to exertion of maximum wave power on these sectors due to a combination of steep slope and ramp like submarine topography

evaluation of tsunami flooding using geomorphologic evidence abstract whatever the generating mechanism of a tsunami may be this event can discharge destructive energy along coastal areas and produce widespread inundation the presence of large boulders along rocky coasts could be a useful indicator to understand the extent of the impact of past tsunami floods a detailed study of the deposited boulder features size shape and rock density and their initial position prior to the transport is extremely important when reconstructing the possible morphodynamic scenario s applying the appropriate equations is important when aiming to assess the maximum extent of flooding the integration of morphological and hydrodynamic data allows for an estimation of the water level during the tsunami event responsible for boulder transport moreover it is possible to calculate how far the impacting wave flooded inland this is a function of the wave parameters and of the degree of roughness of the flooded terrain that is expressed by the manning number to evaluate its probable average value experimental data computer simulations and post tsunami surveys have been performed in two sectors of the southern apulia coastline characterised by the presence of tsunami boulder fields and or ridges the surveys in each site have allowed for the calculation of the boulder sizes the estimation of their pre transport location and the extent of inland flooding data have been processed using a geographic information system gis as a result a flooding map useful in planning future possible actions for coastal area use has been produced

emplacement and movement of boulders by known storm waves field evidence from the okinawa islands japan abstract field observations from previous studies of boulder movements were compiled to augment our own work on boulders that have been displaced by storm waves during recent typhoon events in the okinawa islands japan to elucidate the ability of storm waves to move boulders our observations reveal that recent storm waves displaced by sliding and overturning 100 ton boulders emplacing them on the reef or high cliff tops and that storm waves might also be capable of displacing 200 ton boulders on the reef the weights of storm wave boulders at the okinawa islands are of comparable order to those boulders displaced by historical tsunami origins consequently boulder weight alone is an inappropriate parameter to discriminate between tsunami or storm wave processes however these heavy storm wave boulders are close to the reef and cliff edges while tsunami boulders can be deposited much further inland hence horizontal displacement distance of boulders could be a useful parameter to discriminate boulders deposited by the tsunami and storm waves on the wide fringing reef the storm wave boulders were characteristically concentrated on the southeastern pacific ocean sides of each island but large boulders are rarely found on the northwestern east china sea side this is probably because the storm wave intensities are generally stronger at the southeastern side than at the northwestern side although differences of reef strength and initial condition of boulders should also be taken into account consideration of the high frequency of typhoons at the area suggests that effects of the storm waves and the consequent displacement of boulders on the reef might have contributed to the formation of the reef moat framework that typifies the okinawa islands especially if the moat is located within the transport limit of the storm wave boulders approximately 300 m from the reef edge at the islands

multi proxy evidence for holocene lake level and salinity changes at an loch mor a coastal lake on the aran islands western ireland abstract curves for holocene lake levels and salinity changes are presented for an loch mor a small oligohaline lake on the aran islands off the west coast of ireland based on palaeoecological investigations of a 12 m long lake sediment core new insights are also provided into holocene sea level change in the galway bay region particular emphasis has been placed on the ostracod fauna both past and present salinity and lake level changes were reconstructed from the fossil ostracod assemblages based on the known tolerances of individual species and on the assemblages as a whole additional evidence was provided by other proxies including strontium isotope ratios derived from ostracod shells and other carbonates plant macrofossil and pollen analyses and sedimentological changes the early holocene pre boreal i e 11 5 10 ka was characterised by low lake levels and slightly elevated salinity values probably the result of high evapotranspiration and low precipitation rather than elevated sea levels early holocene plant and animal migration to the island does not seem to have been impeded but relative sea levels were not necessarily so low below 40 m a s l that landbridges were present to the mainland between ca 10 and 8 5 ka relatively high lake levels prevailed at 8 3 and 7 5 ka minor fluctuations lowering of the lake level occurred that are assumed to relate to early holocene abrupt events beginning at 7 05 ka lake levels declined sharply a general trend towards rising lake levels started at ca 6 4 ka and accelerated at ca 5 6 ka as runoff increased as a result of neolithic clearances at ca 4 8 ka lake levels began to rise once again probably in response to changes in rainfall and or evapotranspiration and runoff lower lake levels during the first half of the 1st millennium ad were probably a response to decreased runoff as a result of a drier climate coupled with regeneration of woody vegetation the sharpest rise in both lake levels and salinity began during the ninth century ad which is attributed to a rapid rise in relative sea level

how does wave impact generate large boulders modelling hydraulic fracture of cliffs and shore platforms abstract boulder quarrying by large waves along steep high energy coastlines contributes to erosion both by causing inland migration of cliff faces and by vertical lowering of coastal platform surfaces it also leads to the formation of coastal boulder deposits cbd above and inland of the high water mark we describe mechanisms by which hydraulic fracture creates boulders from cliffs and bedrock platforms intense fluid pressures are induced by wave impact on the base of overhanging ledges and also along interior surfaces as cracks fill with water during wave runup and overtopping these processes impose large loads on the overlying rock and bending stresses thus induced can create or propagate microcracks in the rock repeated loading leads to complete fracture and detachment of bedrock slabs which are liberated as boulders we consider these processes using the aran islands ireland as a type locality both because cbd there are well documented and because flat lying strata and orthogonal joint patterns yield tabular bedrock geometry which lends itself to modelling the loaded rock is modelled as a beam with a microcrack that is fractured by a bending stress from an applied hydrodynamic load this simple approach allows us to examine general scalings and dependencies we determine a condition for fracture relating the fluid pressure loaded area fracture stress microcrack position and geometry in some situations the fluid pressure need only be a fraction of the fracture stress fracture is most likely to occur during extreme wave conditions and when the exposed rock has a large eroded area for loading the balance of forces suggests that larger beams break more easily facilitating the creation of large boulders

distribution geomorphology and lithofacies of cliff top storm deposits examples from the high energy coasts of scotland and ireland abstract cliff top storm deposits ctsds occur on cliffs at elevations of up to 50 m above sea level at exposed sites on the deep water coasts of the british isles this study examines the distribution geomorphology and lithofacies of ctsds at sites from shetland orkney caithness and the outer hebrides in scotland and from the aran islands in galway bay in ireland ctsds are generated largely by the quarrying of blocks from the cliff top and transported by green water bores across cliff top platforms and ramps to be deposited in backing ridges or as debris spreads maximum boulder sizes reach 48 m 3 but it is likely that much larger blocks can be quarried prior to disintegration during transport eye witness accounts and field mapping demonstrate that formation and modification of ctsds has continued during major storms over recent decades recent ctsds bury a range of man made debris but older deposits lack this and instead show weathering effects that indicate a longer residence time in shetland osl dates on intercalated sands suggest that the oldest ctsds date from 800 ad radiocarbon dates on shell buried inside ctsd ridges relate to major storms between 1700 and 1900 ctsds represent an overlooked archive of storm sedimentation that has great potential for the elucidation of local storm chronologies ctsds also provide evidence of wave impacts on any part of the cliff face or top in fundamental contrast to the concentration of wave action at the cliff foot implicit in traditional models of the erosion of rock coasts

geological and historical records of tsunami in australia abstract the indian ocean tsunami iot of 2004 has resulted in significant interest within australia about the record of tsunami for the continent because an understanding of tsunami hazard begins with a catalogue of past events here a preliminary catalogue of tsunami affecting australia is presented the catalogue contains entries for 57 tsunami events the oldest event is dated at 3 47 ga the most recent is the july 17th 2006 forty four tsunami were recorded on the new south wales coast although the nw coast of western australia records a significant number of events forty seven events have affected australia since ad1858 maximum run up for an historic event is 6 m asl whilst the maximum run up for a palaeotsunami event is reported at an elevation of at least 100 m asl twenty three percent of historic australian tsunami were generated by unknown causes and papua new guinea the solomon islands and indonesia collectively represent the most important source area of historic tsunami for australia geological records for palaeo and historic tsunami are identified and summarised the geological record of tsunami represents a potentially important source of information for australian tsunami however at the present time the geological record is both limited and controversial and future research should seek to re examine proposed geological evidence of tsunami from an analysis of this preliminary catalogue of australian tsunami a series of key research priorities have been identified to guide future research in the region

the origin and dynamics of coastal boulders in a semi enclosed shallow basin a northern adriatic case study abstract this paper documents the analysis of a coastal boulder deposit that was recently identified along the northern adriatic coast premantura promontory istria croatia accumulations of large boulders have not previously been reported in the northern adriatic which can be viewed as a semi enclosed basin a multidisciplinary approach was used to investigate the site including geological and geomorphological surveys together with the use of an unmanned aerial vehicle uav digital photogrammetric analysis hydrodynamic modelling and 14c ams datings measurements of boulder position elevation size shape and density were fed into hydrodynamic equations that are used to estimate the minimum storm and tsunami wave height required to enable the accumulation of boulders biogenic marine carbonate encrustations observed on 14 boulders suggest the infra and sublittoral zones as source areas while for most of the boulders a subaerial origin is hypothesised the boulder deposit occurs on a flat promontory where the topography together with the stratified limestone bedding planes and dense joint pattern constitute the predisposing factors for boulder size and detachment comparisons between satellite images taken between 2008 and 2017 pictures collected from internet and a 2012 snorkel survey of the istrian coast made it possible to highlight the emplacement of a boulder with an estimated weight of 7 65 t during late 2013 or early 2014 the study examines the mechanisms that may be responsible for the detachment and transport of these large limestone rock fragments from the emergent part of the coast and from the sea bed towards inland areas the results suggest the occurrence of very recent extreme weather conditions as well as multiple historical storm events and exclude a tsunami origin of the boulders

evaluating the impacts of huge waves on rocky shorelines an essay review of the book tsunami the underrated hazard abstract tsunami the underrated hazard draws together and summarizes a wealth of information about the nature impacts and causes of tsunamis written from a natural hazards perspective the book stresses that large tsunamis can affect even protected coasts that have not experienced large tsunamis historically many deposits and erosional features described and discussed as tsunami signatures have yet to be linked specifically with tsunamis cited references in the book do not necessarily support a tsunami origin for these features because accepted scientific citation practices have not been followed although rocky shorelines in southeastern australia the hawaiian islands and elsewhere generate and preserve a variety of boulder and block deposits and erosional features their sediment dynamics and geomorphology are poorly studied and unequivocal criteria for distinguishing between deposits of storms and tsunamis have yet to be developed despite its shortcomings this book should be on the library shelves of all marine geoscientists who study modern and ancient shorelines however it should be used with great circumspection because the process product relationships it assumes are equivocal

rapid sea level and climate change at the close of the last interglaciation mis 5e evidence from the bahama islands the geology of the last interglaciation sensu stricto marine isotope substage mis 5e in the bahamas records the nature of sea level and climate change after a period of quasi stability for most of the interglaciation during which reefs grew to 2 5 m sea level rose rapidly at the end of the period incising notches in older limestone after brief stillstands at 6 and perhaps 8 5 m sea level fell with apparent speed to the mis 5d lowstand and much cooler climatic conditions it was during this regression from the mis 5e highstand that the north atlantic suffered an oceanographic reorganization about 118 3 ka ago during this same interval massive dune building greatly enlarged the bahama islands giant waves reshaped exposed lowlands into chevron shaped beach ridges ran up on older coastal ridges and also broke off and threw megaboulders onto and over 20 m high cliffs the oolitic rocks recording these features yield concordant whole rock amino acid ratios across the archipelago whether or not the last interglaciation serves as an appropriate analog for our greenhouse world it nonetheless reveals the intricate details of climatic transitions between warm interglaciations and near glacial conditions

boulder transport by storms extreme waves in the coastal zone of the irish west coast abstract this study is concerned with large boulders located along exposed shorelines in higher latitudes which have become dislocated onshore by winter storms and have moved against gravity to identify the transportation processes that these boulders have undergone in detail their direct investigation during storm wave conditions is necessary or at least near time inspections after extraordinary wave events as both methods are rare a wide range of questions and contradictions with regards to the processes that have acted on these boulders remains despite a lack of applicable methods as for fine sediments the depositional environment and processes of boulder movement can be determined from geomorphologic evidence in the landscape itself examples are presented in this paper to progress understanding of boulders in rocky coastal environments qualitative and quantitative data are acquired during a near time inspection following extreme storms in winter 2013 14 with special focus on an extraordinary boulder site near doolin at the entrance to galway bay central west coast of ireland the comparison of these data to previously published research on coastal boulder movement results in agreements and discrepancies e g on boulder forms and mode of transport difference in wave and bore transport which are discussed

tsunami and palaeotsunami depositional signatures and their potential value in understanding the late holocene tsunami record in recent years much research on modern and palaeotsunami deposits has been published from these studies a range of signature types has been identified identifying and dating such deposits is an important element in understanding late holocene tsunami hazard and risk however important questions such as do modern and palaeotsunami leave similar or dissimilar traces do tsunami leave the same signatures all around the world or are there significant variations and what is the actual record of tsunami in different parts of the world still remain answering these questions is not an easy task but examining megatsunami flood deposits should shed some light on these questions because such high magnitude events should leave very clear and detailed traces within the coastal landscape the coast of se australia is reported to have been affected by numerous palaeomegatsunami in the late holocene as such the coast of new south wales offers an important natural laboratory to examine in detail deposits associated with such events here we summarize the published characteristics of modern and palaeotsunami deposits globally and within australia we briefly outline the tsunami risk to australia before examining a site called minnamurra point on the coastline of se australia south of sydney that has previously been described as containing evidence for a palaeomegatsunami of an unknown age we describe the results of a detailed coastal survey field stratigraphic investigation and various standard laboratory analyses surprisingly we are unable to replicate the previously reported findings of tsunami deposits whilst we prefer the interpretation that the sequence is an in situ soil the sediment sequence examined contains none of the usually reported lines of evidence to demonstrate tsunami provenance we recognize and discuss the significance and difficulty of identifying tsunami deposits in the field and consider the implications of our findings to the wider debate about the preservation of tsunami deposited sediments

sedimentology of rocky shorelines 4 coarse gravel lithofacies molluscan biofacies and the stratigraphic and eustatic records in the type area of the pleistocene hulopoe gravel lanai hawaii abstract during the pleistocene the south flank of lanai was the site of repeated erosion and deposition as a consequence of glacio eustasy superimposed on tectono isostasy throughout this time terrigenous and bioclastic gravel was generated along mainly rocky shorelines gravelly sediment was deposited in topographically low areas of the shoreface and inner shelf that later were uplifted isostatically the sedimentary lithofacies and biofacies in these deposits are distinctive but they represent a deposystem and suite of environments that hitherto have not been studied systematically these unrecognised circumstances have fuelled controversies about the nature and significance of the hulopoe gravel most notably the claim that it represents a mega tsunami deposit the hulopoe gravel in its type area displays a lithofacies succession that encompasses a complete disconformity bounded transgressive regressive cycle on a sand poor rocky shoreline this succession incorporates not only a distinctive vertical assemblage of rocky shoreline litho and biofacies but also internal disconformities that record episodes of erosion and non deposition during shoreline migration repetition of the lithofacies succession imparts overall stratigraphic order to the hulopoe gravel four unconformity bounded transgressive regressive cycles correspond to eustatic highstands of oxygen isotope stages 5 and 7 superimposed on continuing tectono isostatic uplift driven by growth of the island of hawaii this study of the hulopoe gravel demonstrates that the sedimentary record of mixed volcaniclastic carbonate depositional systems developed on rocky shorelines of tropical and subtropical oceanic island coasts can be preserved this record may include depositional products of both transgressive and regressive shorelines although tsunami and giant submarine landslides are known to occur in the hawaiian islands deposits and features that result from tsunami inundation above the shoreline such as might be expected from landslide related mega tsunami have not been recognised in the type area of the hulopoe gravel rocky palaeoshoreline records on oceanic volcanic islands may yield oceanographic and climatic clues that complement data obtained from other palaeoshoreline types

a comprehensive hydro geomorphic study of cliff top storm deposits on banneg island during winter 2013 2014 large clastic cliff top storm deposits called ctsds are one of the most remarkable signatures that characterizes extreme storm wave events on coastal cliffs hence the study of ctsds is of key importance for understanding and predicting the impacts of extreme storm wave events on rocky coasts or establishing proxies for storm intensity the present study uses new data including hydrodynamic measurements in both deep and intertidal waters and records of ctsds displacement and deposition across banneg island during the stormy winter 2013 2014 two drone based surveys were carried out in january 2013 pre storms and in april 2014 post storms in addition complementary field observations were carried out during the winter providing a comprehensive and detailed dataset concerning the hydrodynamic measurements nine pressure sensors deployed along four cross shore profiles on the western coast of the island recorded wave and water level conditions between december 2013 and april 2014 aerial orthorectified photographs and digital elevation model of differences provide a detailed spatial description of cliff erosion and the reworking of cliff top storm deposits after the storms 172 fresh scars corresponding to quarrying in the bed rock were localized above high spring tide water level 507 blocks were transported up to 40 m inland at altitudes of 8 to 14 m above mean sea level and the tracks of 170 of them were identified the water levels and wave parameters estimated from the pressure sensor measurements provided accurate information on the maximum water elevation reached during the largest storms at the sensor locations and were extrapolated to provide run up elevation along the four survey profiles for the whole winter 2013 2014 the results demonstrate that a large number of overwash episodes occurred at times of high tides and energetic waves these episodes generally correspond to morphological changes this study confirms the major role played by extreme storm wave events on ctsds quarrying transport and deposition on banneg island and clearly identify the events of major evolutions

extraordinary boulder transport by storm waves west of ireland winter 2013 2014 and criteria for analysing coastal boulder deposits abstract before and after photos of supratidal coastal boulder deposits cbd in the west of ireland show that storms in the winter of 2013 2014 transported boulders at elevations up to 29 m above high water and at inland distances up to 222 m among the clasts transported are eighteen weighing more than 50 t six of which exceed 100 t the largest boulder moved during those storms weighs a fairly astonishing 620 t the boulders moved in these recent storms provide pinning points for mapping storm wave energies on coasts their topographic positions mark elevations and distances inland reached by wave energies sufficient to dislocate those specific masses taken together the cbd data reveal general relationships that shed light on storm wave hydrodynamics these include a robust correlation inverse exponential between maximum boulder mass transported and emplacement height above high water the greater the elevation the smaller the maximum boulder size with a dependency exponent of about 0 2 times the elevation in metres there is a similar relationship although with a much smaller rate of change exponent 0 02 between boulder mass and distance inland which holds from the shoreline in to about 120 m coastal steepness calculated as the ratio of elevation to inland distance seems to exert the strongest control with an inverse power law relationship between maximum boulder mass and slope ratio the more gentle the topography the larger the moved boulders quantifying cbd dynamics helps us understand the transmission of wave energies inshore during high energy storm events the transported boulders documented here are larger than many of those interpreted to have been moved by tsunami in other locations which means that boulder size alone cannot be used as a criterion for distinguishing between tsunami and storm emplacement of cbd the biggest blocks up to 620 t are new maxima for boulder mass transported by storm waves we predict however that this record will not last long the 2013 2014 storms were strong but not extreme and there are larger boulders in these deposits that didn t move on this occasion bigger storms will surely move larger clasts and clasts at greater distances from the shoreline these measurements and relationships emphasise the extreme power of storm waves impacting exposed coastlines and require us to rethink the upper limits of storm wave energy at coasts

sedimentology of rocky shorelines 5 the marine samples at 326m from stearns swale lanai hawaiʻi and their paleo environmental and sedimentary process implications abstract fossiliferous gravels on lanai one of the smaller hawaiian islands are known collectively as the hulopoe gravel since 1984 several workers have attributed these gravels to deposition from the run ups and retreats of mega tsunami other workers before and since have interpreted the gravels as rocky shoreline deposits exposed by island uplift the existence of harold stearns makana paleoshoreline on lanai at 326 365 m elevation is particularly controversial in 1936 stearns collected some marine molluscan fossils from a site at 326 m elevation on the southern slope of lanai now known as stearns swale details of the site the fossils and his installed markers were recorded in his field note book now held by the us geological survey in honolulu the fossils were lodged in the national museum of natural history in washington d c during ww ii the 326 m site became a military installation and stearns markers and any remaining fossils were destroyed we have examined stearns notebook the 326 m site and the fossils two types of sediment adhere to the fossils a weakly cemented well rounded biocalcarenite grainstones with minor subrounded basalt fragments b calcite cemented sub rounded to well rounded volcanic litharenite or lithrudite with some bioclasts the fossil molluscs and the bioclasts in the adhering sands represent organisms typical of hawaiian rocky shorelines and adjacent submarine slopes these features are consistent with 1 deposition of the sediments on or closely overlying an unconformity surface cut in basalt bedrock in the vicinity of a rocky shoreline they are also consistent with 2 derivation of the materials from rocky shorelines or shorefaces at lower elevations and their transport up slope by waves generated by a category 5 hurricane or by a mega tsunami we prefer the first scenario as lanai s vertical mobility is indicated by at least ten topographically distinct shoreline related deposits located at various elevations on or adjacent to lanai including six submerged terraces on its western flank

long term variability of supratidal coastal boulder activation in brittany france abstract high energy supratidal coastal boulder deposit scbd dynamics were investigated on vierge island and pors carn point north and south of western brittany france respectively morphological changes induced by boulder transport and quarrying were quantified using high resolution topographic survey data taken between 2012 and 2017 additional in situ wave parameters and water levels were also recorded over this period 2014 2017 in order to compute the maximum water levels and assess the relationship between scbd morphological changes and specific hydrodynamic conditions during extreme water levels for maximum water levels exceeding a one in ten year event scbds were broadly reworked up to 40 of the total volume during lower intensity events for which maximum water levels were still very high morphological changes represented 1 to 5 of the total volume these morphological and hydrodynamic observations were then used to calibrate a chronology of scbd activation events based on 70 years of hindcast winter maximum water levels these long term time series showed great interannual variability in scbd activation but no significant long term trend winter frequency scbd activation was better correlated to the wepa index r 0 46 than the nao index r 0 1 therefore the wepa index can be considered to be a more significant climate proxy for assessing storm related geomorphic changes in the temperate latitudes of the n e atlantic basin 36 52 n including the brittany coast the potential of scbds as a morphological storm proxy for macrotidal high energy rocky coasts is addressed

catastrophic wave erosion bristol channel united kingdom impact of tsunami abstract on january 30 1607 a massive wave from the ocean surged up bristol channel in the united kingdom flooding more than 500 km2 of lowland along 570 km of coast it killed 2000 people and is considered britain s worst natural disaster on land the wave occurred on a fine day and surprised inhabitants contemporary descriptions of the event have many of the characteristics of accounts of recent catastrophic tsunamis geomorphic evidence for tsunamis in the channel can be found in the form of transported and imbricated boulders bedrock sculpturing on coastal platforms and ramps and at isolated locations wholesale erosion of the coastal landscape hydrodynamic calculation of the height of the tsunami and flow velocities can be derived from boulder dimensions tsunami wave height increased from 4 m in the outer bristol channel to more than 6 m within the inner severn estuary theorized flow velocities range between 11 8 and 18 1 m s 1 increasing up the estuary under topographic enhancement thes

abnormal historic sea surface fluctuations sw england abstract this paper presents a series of documentary accounts of abnormal sea surface changes that have affected the coastline of sw england during historic times an attempt is made to consider possible origins for individual events although it is recognised that certain episodes of coastal flooding appear to have no simple explanation however certain coastal floods appear to have been generated by tsunamis triggered by far field offshore earthquakes

scaling relationships of joint and vein arrays from the burren co clare ireland abstract we present a study of the systematics of veins and joints in carboniferous limestones of the burren ireland scaling relationships were established for fracture arrays mapped from low elevation aerial photographs that image fractures on numerous limestone pavements for areas up to ca 1 km2 the veins and joints occur in the same sequence but have contrasting scaling properties the veins strike north south and cut many beds to form vertically persistent non stratabound arrays they are strongly clustered and have scale invariant geometric properties vein geometries suggest they grew sub critically under relatively high differential stresses during north south directed variscan compression the joints form stratabound arrays with regular spacings that scale with bed thickness they show greater strike variation than the veins and have lognormal length distributions the joints formed during uplift under low differential stress conditions the contrasting scaling properties of the joints and veins are attributed to different overburden stresses at the time of formation the veins formed at greater depths than the joints in conditions that favoured fracture propagation across mechanical discontinuities resulting in the development of non stratabound scaling properties

reassessment of hydrodynamic equations minimum flow velocity to initiate boulder transport by high energy events storms tsunamis abstract coastal boulders are good evidence of high energy events but the distinction between storm and tsunami boulders remains difficult to identify and mathematical models are still in their preliminary stages in a pioneering contribution nott 1997 2003 developed hydrodynamic equations to assess the minimum wave height required to initiate transport of a coastal boulder by tsunamis or storm surges these equations are widely cited and used but they can be improved in this study nott s equations have been revised 1 the equation for the submerged boulder scenario has been revised by rearranging the lift area of the lift force 2 the subaerial boulder scenario has been reconsidered by rearranging lift area and omitting inappropriate use of inertia force and 3 the joint bounded scenario was revised by balancing force components in the lifting direction and the effect of slope at the pre transport location is tested calculations are performed for four case studies boulders in western and eastern australia data after nott 1997 2003 boulders in southeastern italy data after scicchitano et al 2007 storm boulders in iceland data after etienne and paris 2010 and 2004 tsunami boulders in sumatra data after paris et al 2009 the minimum flow velocity required to initiate the transport of submerged boulders in the revised equation is less than that in nott s equation e g reductions up to 56 for submerged boulders and 65 for joint bounded blocks the minimum flow velocity required to initiate the transport of subaerial boulders from the revised equation also differed in comparison with nott s equation e g 4 22 for boulders detached from a seawall by the 2004 tsunami in sumatra while nott s equation was not applicable to some boulders e g beach rock boulders transported from the nearshore by the 2004 tsunami if we consider a joint bounded scenario for storm boulders in iceland the minimum flow velocity differs 43 to 41 from the results from nott s equation a boulder transport histogram is then introduced to represent the range of flow velocity that satisfies the requirements for initial transport of a boulder in different modes sliding rolling and saltation the boulder transport histogram can be used to predict the possible initial transport mode of a boulder from the flow velocity these theoretical results are compared to field data thus suggesting the initial transport mode of boulders and their pre transport locations the boulder transport histogram would be a valuable tool to reconstruct the magnitude of prehistoric high energy events such as tsunamis or storm surges in terms of flow velocity

numerical simulation of wave overtopping of coastal structures using the non linear shallow water equations a one dimensional high resolution finite volume model capable of simulating storm waves propagating in the coastal surf zone and overtopping a sea wall is presented the model amazon is based on solving the non linear shallow water nlsw equations a modern upwind scheme of the godunov type using an hll approximate riemann solver is described which captures bore waves in both transcritical and supercritical flows by employing a finite volume formulation the method can be implemented on an irregular structured boundary fitted computational mesh the use of the nlsw equations to model wave overtopping is computationally efficient and practically flexible though the detailed structure of wave breaking is of course ignored it is shown that wave overtopping at a vertical wall may also be approximately modelled by representing the wall as a steep bed slope the amazon model solutions have been compared with analytical solutions and laboratory data for wave overtopping at sloping and vertical seawalls and good agreement has been found the model requires more verification tests for irregular waves before its application as a generic design tool

boulder accumulations related to storms on the south coast of the reykjanes peninsula iceland coastal boulder accumulations are often mentioned in the literature even though their interpretation remains difficult especially along rock coasts affected both by storms and tsunamis studies on the geomorphic impact of such high energy events are actually of great interest since their intensity and frequency are key issues for the future evolution of coasts in the framework of the global change the southwest coast of iceland faces the powerful storms of the north atlantic ocean with wave heights of more than 15 m the probability for past and present tsunamis to hit this coast is very low in this paper we describe boulder accumulations along the volcanic rock coast of reykjanes southwest iceland they consist of cliff top boulders clusters and ridges beaches and boulder fields large boulders up to 70 t in weight have been transported and deposited up to 65 m inland 6 masl the maximum limit of boulder deposition and driftwood was found respectively 210 m and 550 m inland storms appear to be a predominant factor in the geomorphic evolution of reykjanes coasts our observations also give new insight for the interpretation of coastal boulder accumulations processes of erosion and deposition by tsunamis are a rising topic in the literature and the effects of recurrent and powerful storms are neglected

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

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

morphological controls and statistical modelling of boulder transport by extreme storms abstract the study of coastal boulder accumulations generated by extreme marine events and of the energy and frequency involved in boulder transport is of paramount importance in understanding the risk associated with extreme marine inundations one of the frequently asked questions is whether the deposits are storm or tsunami related both events being characterized by different return periods boulder transport by storms was monitored on the west coast of portugal significant changes were detected in boulders position as a result of extreme inundation by the 2013 2014 winter storms results presented in this work indicate that the wave power associated with the christina and nadja storms occur once every three years however this interval is not supported by field observations of boulder displacement which suggests that wave power over predicts boulder movement in the study area furthermore wave parameters from the christina and nadja storms were very similar but have generated different impacts in the boulder accumulation described herein differences include the magnitude and direction of boulder movement and are most likely associated with distinct tidal levels during the events higher tide levels generated an increase in the sea surface level and thus in the reach of waves which generated displacement of larger boulders and consequent cross shore contribution in boulder transport regardless the combination of monitoring campaigns wave data and statistical modelling of extreme values indicate that boulder transport by storms is more frequent than initially expected based on recorded boulder movements we present a conceptual model for boulder ridge formation and development and identify significant control of incoming flow by local geomorphological topographical features storm events not less frequent tsunamis are identified as the events responsible for modulating this rocky coastline these results question a direct attribution of coastal boulder deposits to tsunamis in coastal regions with a high risk of tsunami inundation