effects of direct and indirect heating on the validity of rock weathering simulation studies and durability tests rock surface and subsurface temperature responses in samples exposed to direct heating insolation under natural hot desert conditions reveal considerable variability between lithologies related to differences in thermal properties especially albedo and thermal conductivity however when the same samples are heated indirectly by air in an oven based environmental cabinet lithological differences in temperature response disappear and all samples attain temperatures similar to the air temperature within the cabinet rates and patterns of rock decay produced in such environmental cabinets may not therefore reflect those encountered under natural conditions where breakdown is related to micro environmental conditions at the rock air interface and where rock temperature is one of the most important controlling factors in addition to implications for assessment of weathering effectiveness use of only indirect forms of heating affects the determination of comparative rock durability because all rock types are cycled through the same temperature regimes because temperature exerts such a major control on rock breakdown through its control on physical and chemical weathering processes all significant factors influencing it must be included in the design of weathering simulations and durability tests

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

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

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

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

sub aerial weathering of chalk shore platforms during harsh winters in southeast england abstract chalk shore platforms are a common feature of the intertidal zone of parts of southeast england cracking and spalling of platform surfaces was widespread during exceptionally harsh winter weather in january 1985 and february 1986 damage was mostly confined to the upper reaches of the platforms and to surficial boulders laboratory simulations indicate that destructive freezing occurs only when the internal rock temperature drops below 4 5 c under the minimum air temperatures recorded during the winters of 1985 6 this will be several hours after rock surfaces are exposed to the air although temperatures as persistently low as those recorded in the winters of 1985 6 are relatively rare in southeast england temperatures sufficiently low to induce destructive freezing are encountered quite regularly and it is suggested that frost weathering of the platforms occurs during many winters although on a lesser scale than in 1985 6 frost weathering tends to remove surface irregularities and wear back the platform steps

cavernous weathering in the capitol reef desert utah tafoni and honeycomb weathering are abundant in sandstones at capitol reef national park cavities are particularly common in talus blocks resting on alkali rich soil in vertical walls of desert washes and in sandstones containing calcareous cement chemical analyses x ray diffraction data and field observations suggest that salt weathering is the most important cause of disintegration but dissolution of calcite cement also occurs in calcareous sandstones cavernous weathering at capitol reef produces cavities similar in appearance to features found in arkose outcrops along the coast of northwest washington even though the environmental conditions at these two locations are very different

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

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

salt weathering influence of evaporation rate supersaturation and crystallization pattern micro and macroscale experiments which document the dynamics of salt damage to porous stone have yielded data which expose weaknesses in earlier interpretations previously unexplained differences are found in crystal morphology crystallization patterns kinetics and substrate damage when comparing the growth of mirabilite na2so4 10h2o and thenardite na2so4 versus halite nacl the crystallization pattern of sodium sulphate was strongly affected by relative humidity rh while a lesser rh effect was observed for sodium chloride macroscale experiments confirmed that mirabilite crystallizing at rh 50 per cent and thenardite crystallizing at rh 50 per cent tend to form subflorescence in highly localized areas under conditions of constant rh and temperature this crystallization pattern was more damaging than that of halite since halite tended to grow as efflorescence or by filling the smallest pores of the stone in a homogeneous fashion a result which contradicts wellman and wilson s theoretical model of salt damage low rh promoted rapid evaporation of saline solutions and higher supersaturation levels resulting in the greatest damage to the stone in the case of both sodium sulphate and sodium chloride crystallization at any particular crystallization condition sodium chloride tended to reach lower supersaturation levels resulting in the crystallization of isometric crystals and created negligible damage while sodium sulphate reached higher supersaturation ratios resulting in non equilibrium crystal shapes resulting in significant damage esem showed no damage from sodium sulphate due to hydration instead after water condensation on thenardite crystals rapid dissolution followed by precipitation of mirabilite took place resulting in stone damage by means of crystallization pressure generation it is concluded that salt damage due to crystallization pressure appears to be largely a function of solution supersaturation ratio and location of crystallization these key factors are related to solution properties and evaporation rates which are constrained by solution composition environmental conditions substrate properties and salt crystallization growth patterns when combined with a critical review of salt damage literature these experiments allow the development of a model which explains variations in damage related to combinations of different salts substrates and environmental conditions

weathering of sandstone by the combined action of frost and salt preliminary results from a continuing series of laboratory experiments designed to examine the combined effects of salt and frost weathering indicate that some salts greatly enhance the breakdown of rocks by frost samples of ardingly sandstone from southeast england were soaked in saturated solutions of sodium chloride or sodium sulphate and subjected to alternating cycles of freezing and thawing rapid disintegration of the sandstone occurred within twenty cycles in each of the salt solutions in contrast samples subjected to freezing and thawing in deionized water suffered very little damage unless they were saturated under vacuum when samples were subjected to twenty cycles of wetting and drying at temperatures above 0 c those soaked in deionised water or sodium chloride suffered no appreciable damage but those soaked in sodium sulphate rapidly disintegrated tentative explanations of these results are offered the enhancement of frost weathering by salt appears to have been overlooked by many writers yet it is likely to be an important geomorphological process in those areas of mid and high latitudes where rocks are saturated with sodium salts

weathering effects on the geotechnical properties of argillaceous sediments in tropical environments and their geomorphological implications outcrops of young sedimentary argillaceous rocks with well developed fabric display rapid changes in their properties when subject to tropical weathering the change in the materials is often accompanied by mass movement activity and the geomorphological consequence in terms of landforms is usually the development of badlands topography detailed field and laboratory studies have been undertaken on the joe s river formation barbados and the lichi melange taiwan both are sedimentary mudrocks with well developed scaly fabrics physical and geotechnical laboratory tests have been conducted on samples collected from type site locations to elucidate associations between material properties earth surface processes and landform development while the inherent physical properties show little or no difference in the transition from unweathered to highly weathered materials by applying the critical state model the mudrock geotechnical properties can be shown to change significantly as weathering commences material strength surprisingly increases only after a period of more extensive weathering do mechanical properties confirm increasingly incompetent materials the initial strength increase appears to be due to weathering induced modification of the fabric the subsequent strength drop is a product of weathering induced modification of both the fabric and the in situ intact sediment it is suggested that by applying the critical state model a greater consideration can be gained of the geotechnical response of the sediments to weathering

air compression as a mechanism for the underdamped slug test response in fractured glacier ice 1 artificial perturbations of borehole water levels known as slug tests are a useful means of characterizing the glacier hydrologic system slug tests were performed on bench glacier alaska in 21 boreholes over three field seasons during the transition from a winter to a summer drainage mode fifty four slug tests were conducted with water level monitoring in up to five boreholes adjacent to the slugged borehole seven of the slug tests were performed in conjunction with dye dispersion tests to identify water pathways within the slugged borehole following perturbation nearly 60 of monitored adjacent boreholes showed a hydraulic connection to the slugged borehole via the glacier bed the nature and degree of connectivity was temporally variable suggesting that the drainage network at the bed was highly dynamic on a daily timescale and spatial scale of tens of meters the variability of slug test responses over time and space limit the feasibility of six alternative explanations for the oscillatory water level behavior characteristic of the underdamped response we propose a seventh that is that coherent air packages are a reasonable means of producing the compliance needed to generate the underdamped slug test responses on bench glacier and that these air packages may exist within the glacier at the tips of subglacially propagated fractures

the origin of honeycomb weathering honeycomb weathering occurs throughout the world but the origin remains a matter of controversy wind erosion exfoliation frost shattering and salt weathering have been proposed as explanations although few attempts have been made to substantiate these hypotheses with chemical or mineralogical studies chemical analyses and field observations indicate that honeycomb weathering in coastal exposures of arkosic sandstone near bellingham washington results from evaporation of salt water deposited by wave splash microscopic examination of weathered surfaces show that erosion results from disaggregation of mineral grains rather than from chemical decomposition thin walls separating adjacent cavities seem to be due to protective effects of organic coatings produced by microscopic algae inhabiting the rock surface cavity walls are not reinforced by precipitation of elements released by weathering as has often been suggested at other locations honeycomb weathering develops rapidly and can be observed on surfaces that were planar less than a century ago

the micro erosion meter use and limitations detection of anomalies in measurements of low rates of limestone surface lowering with a traversing micro erosion meter mem led to temperature controlled laboratory and field investigations of some sources of error in the method regressions for the correction of temperature change in the instrument and in the stud rock interface were obtained probe erosion tests permitted a correction to be devised and also provided information whereby a measure of operational irregularity was adopted corrections and error terms were applied to field measurements from two southern new south wales karsts and a collection of australian limestone slabs exposed at one site examination of these results and of published mem rates from other parts of the world validated the mem method marine platforms are lowered at such gross rates that these error sources may be neglected there however limestone lowering in terrestrial environments cannot be assumed to proceed at rates which permit this and recommendations are made about procedures to ensure that investigations are prosecuted within the limitations of the method

laboratory simulation of rock weathering by salt crystallization and hydration processes in hot arid environments the results of a series of experiments are reported in this paper which were designed to differentiate between the forces of crystal growth and hydration in salt weathering using a single salt hydrate system sodium sulphate five contrasting rock types and several diurnal temperature relative humidity cycles which permitted or inhibited these processes and simulated ground surface climates in hot arid environments it was shown that hydration of sodium sulphate is an effective mechanism of rock disintegration but that it is significantly less destructive than crystal growth pressure crystallization of thenardite na2so4 is in turn more effective in rock weathering than the crystal growth of mirabilite na2so4 10h2o in general rates of disintegration were most rapid where the diurnal temperature range was extreme and relative humidity lowest

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

parallel retreat of rock slopes underlain by alternation of strata abstract characteristic landscapes e g cuesta cliff and overhang of caprock or stepped terrain formed by differential erosion can be found in areas composed of variable geology exhibiting different resistances to weathering parallel retreat of slopes defined as recession of slopes without changes in their topography is sometimes observed on slopes composed of multiple strata however the conditions needed for such parallel retreat have not yet been sufficiently clarified in this study we elucidated the conditions for parallel retreat of rock slopes composed of alternating layers using a geometric method in addition to evaluate whether various rock slopes fulfilled the conditions for parallel retreat we analyzed topographic data obtained from periodic measurement of rock slopes in the aka kuzure landslide central japan our geometric analysis of the two dimensional slopes indicates that dip angle slope gradient and erosion rate are the factors that determine parallel retreat conditions however dip angle does not significantly affect parallel retreat conditions in the case of steep back slopes slope gradient 40 in contrast dip angle is an important factor when we consider the parallel retreat conditions in dip slopes and gentler back slopes slope gradient

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

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

frost and salt weathering further experimental results a laboratory experiment has been conducted to examine the effects of frost and salt weathering i e physical breakdown by the freezing of salt solutions on a limestone results show that the presence of certain salts in solution can inhibit frost damage these findings are in direct conflict with those presented by goudie 1974 and more recently williams and robinson 1981 comparison of the experimental methods used in each of these three studies suggests that opposing results can be explained in terms of the different experimental procedures which were employed if salt supply is frequent and plentiful then it seems likely that rock breakdown will be enhanced this is the case represented by the experiment of williams and robinson conversely if the salt supply is limited and the amounts of salt remain more or less constant then rock breakdown will be inhibited the case of the present experimental study caution is therefore advocated when attempting to extrapolate laboratory derived results to infer on the behaviour of rocks under natural conditions several environmental situations in which frost and salt weathering may be a possibility are dsiscussed but it is concluded that further field data especially concerning temperature regimes and salt availability at and below rock surfaces in cold regions would be necessary before more definite statements could be made about the efficacy of this process

short term microscale topographic changes of coastal bedrock on shore platforms we report a series of short term diurnal rock surface monitoring studies on inter and supra tidal shore platforms using a traversing micro erosion meter at two sites kaikoura peninsula new zealand and apollo bay victoria australia statistically signi cant day to day changes were measured surface rise and lowering occurred at rates above instrument error with a maximum range of 3 378 mm between 1 697 mm lowering and 1 681 mm rise individual measurements showed rises greater than 2 mm these daily variations reveal that surface lowering and rise occur at a much shorter time scale than previously reported from other studies the patterns observed suggest wetting and drying is the most likely process causing surface changes at these temporal scales we argue that traversing micro erosion meter studies operating at a short term time scale of day to day provide meaningful results that open new opportunities for studying rock weathering and erosion in a coastal environment copyright 2004 john wiley sons ltd

weathering rates on a caribbean reef limestone results and implications abstract weathering of presently raised reef islands provides an analogue for the behaviour of pleistocene reefs made emergent by glacio eustatic falls in sea level micro erosion meter measurements on grand cayman island west indies have shown that high mean weathering rates 1 00 mm yr 1 are restricted to the marine environment large scale landform development is unlikely to have been the product of the last period of exposure but rather the result of successive phases of weathering and reef growth increasing the differential relief of the reef base throughout the pleistocene

modeling weathering pathways and processes of the fragmentation of salt weathered quartz chlorite schist 1 the relationship between the rate of rock breakdown and environmental and geological factors must be understood in order to establish the conditions under which weathering limits erosion in this study qualitative and quantitative models of the rock fragmentation process are fitted to previously published data obtained from laboratory salt weathering trials of quartz chlorite schist weathering was modeled as a combination of 1 a fragmentation event that fragments the parent particle into a number of daughter particles while preserving mass and 2 a fracture probability that determines the probability that a fragmentation event will occur in a given time period we show that observations of the complex breakdown of salt weathered schist are consistent with model assumptions of a simple fracture geometry model and an increase in fracture probability with time for the fragmentation geometry the best fit to the experimental data was achieved by assuming that each fragmentation event involves splitting of the parent particle into two daughter fragments of equal volume for the fragmentation rate the data could best be described with a fracture probability and hence the weathering rate that increased linearly with time this paper shows that it is possible to use a physically based fragmentation model to infer the process of fragmentation for individual particles using a time evolving particle size distribution for the weathering rock fragments

surface swelling of coastal bedrock on inter tidal shore platforms kaikoura peninsula south island new zealand this paper reports the occurrence of swelling of coastal bedrock measured with a traversing micro erosion meter tmem on inter tidal mudstone and limestone shore platforms while numerous micro erosion meter mem studies have been made only a small number have reported surface swelling during this study 24 055 measurements were made with a tmem of those 4047 indicated swelling or 17 of the total number of measurements vertical swelling of up to 8 9 mm was measured and values of 3 and 4 mm were common swelling displayed a complex pattern with minor swelling being superimposed on longer period episodes duration of swelling events in excess of 697 days were recorded while other events were commonly in the order of 3 to 4 months there is a distinct seasonal variation with greater and more frequent swelling occurring during summer months compared with winter explanation for swelling includes the growth of salt crystals in rock lattices and expansion from wetting and drying warm summer temperatures provide the best conditions for both processes swelling appears to be an important precursor to erosion of material from shore platform surfaces the conclusion drawn is that subaerial weathering makes an important contribution to the lowering of the shore platforms on the kaikoura peninsula

ambient noise characteristics of the northwestern barents sea in support of the 1988 1989 cearex drift experiment three anmet ambient noise buoys were inserted on ice floes in a triangular pattern approximately 120 km on a side about 200 km north of svalbard in mid september 1988 the buoys drifted southward passing to the east of svalbard providing hourly measurements of the noise field from 5 4000 hz for 2 4 months extensive environmental data were available with which to examine the effect of wind stress and ice motion on the noise field the median spectra from these three buoys were quite similar with differences of about 3 db being observed the larger differences being at the higher frequencies where local noise effects dominate the spectra were comparable to those found in the eurasian basin in winter a 12 h periodicity was noted in both the noise and ice speed data the result of forcing by tidal or inertial oscillations a 52 h periodicity was noted at one buoy which lasted through the winter and was subjected to recurring synoptic scale storms for frequencies below 100 hz the temporal coherency was about 15 h at low frequencies wind stress was the most important noise correlate followed closely by ice speed the noise field responded rapidly to the passage of storms generated by the icelandic low which migrated over the northern barents sea with the arrival of the noise peak being associated with the time of passage of the storm front past each buoy

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

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

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

tafoni on coastal slopes south devon u k cavernous weathering tafoni development occurs on coastal slopes in greenschist bedrock at elevations up to 40 m above sea level the freshly weathered surfaces of the cavern interiors are irregular in morphology discordant to major rock structure formed by substantially weakened rock and associated with granular weathering debris the weathering debris contains soluble elements in proportions similar to those present in seawater and the penetration of elements associated with sea salts into the weathering surface to estimated depths of at least 0 1 0 2 m is indicated by the presence of chlorine scanning electron microscopy and microprobe analyses suggest that rock breakdown occurs principally through limited chemical weathering at grain boundaries the mechanism for the emplacement of marine salts within sheltered rock surfaces in the tafoni is postulated to be a combination of dry deposition under turbulent atmospheric conditions and wetting by coastal fog

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

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

an investigation into the relationship between salt weathering debris production and temperature an investigation using laboratory simulation has been made using air temperature data for tunisia antarctica and southwest england an experiment with a 50 cycle run produced results which showed significantly greater debris production in the antarctica and tunisian simulations than in the southwest england simulation using x ray analysts to determine salt penetration an inverse relationship between salt penetration and debris production was seen to exist this could be the result of evaporation in the tunisian simulation and rapid freezing in the antarctic simulation concentrating salts in the upper layers of the rock samples in the southwest england simulation no freezing and relatively high humidities allowed greater penetration thus distributing an equal input of salt over a greater area the author tentatively suggests the possible existence of a parabolic relationship between salt weathering and temperature

the impact of landslides and salt weathering on roman structures at high latitudes conway castle great britain a case study conway castle is an immense historical structure dating back to 1289 ac it was built on highly dipping thickbeds of indurated shale argillite and sandstone it is surrounded by conway bay railway lines and tall dense forests indicating high relative humidity and rainfall in this coastal area the castle suffers from weathering noted as honeycomb black crust exfoliation and discoloration with white salt efflorescence at some parts these are diagnostic features for salt weathering as confirmed by the laboratory investigations using scanning electron microscopy x ray diffraction xrd point xrd and hydrochemical analysis the salt is found to be from three sources namely water spray from conway bay that is part of the irish sea chemical alteration of the mortar s carbonate content into sulfate salts by acid rain and wet deposition of air pollutants on the surface of the stone the cracks noted in the southwestern tower of this castle are a result of landslides in this area that resulted from three factors a high dip angle of the indurated sandstone and shale thickbeds about 60 65 to the south under this castle b undercutting of these beds in the dip direction by the surface water of conway bay and c seismic waves generated by the trains passing close to this castle all these factors result in land sliding even at a low rate however the net result is cracks in the tower close to these factors

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

differential weathering of feldspar and pyroxene in an arctic alpine environment the relative relief of adjacent plagioclase and pyroxene minerals was accurately measured on a recently exhumed outcrop of gabbroic rocks in leirdalen southern norway above the level of the former soil surface the feldspars protrude above the pyroxenes whereas below that level the pyroxenes are higher differential relief declines with increasing depth of burial down to 80 cm on exposed surfaces the mean loss of pyroxene relative to feldspar is 103 cm3 m 2 of rock surface with burial down to 50 cm in an arctic alpine brown soil the mean loss of feldspar relative to pyroxene is 179 cm3 m 2 these figures represent minimum amounts of weathering over about 9000 years the results confirm the importance of chemical weathering in arctic alpine environments and the techniques may provide useful physical measures of degree of weathering for use in rate studies and relative dating

a preliminary scanning electron microscope study of honeycomb weathering of sandstone in a coastal environment honeycomb weathering has been observed in a carboniferous sandstone at a coastal location near ballycastle on the north coast of northern ireland specimens of this sandstone have been analysed by x ray diffraction scanning electron microscopy and energy dispersive spectrometry results reveal that calcium sulphate gypsum is the only salt present and is found only at and immediately below the rock surface sem observations suggest that crystallization of salts in pores could easily dislodge quartz grains to promote granular disintegration whilst etching of quartz grain surfaces attests to chemical weathering activity within the rock however the reason for the development of the honeycomb pattern is not known

biogenic origin of coastal honeycomb weathering honeycomb weathering occurs in two environments in late cretaceous and eocene sandstone outcrops along the coastlines of south west oregon and north west washington usa and south west british columbia canada at these sites honeycomb weathering is found on subhorizontal rock surfaces in the intertidal zone and on steep faces in the salt spray zone above the mean high tide level in both environments cavity development is initiated by salt weathering in the intertidal zone cavity shapes and sizes are primarily controlled by wetting drying cycles and the rate of development greatly diminishes when cavities reach a critical size where the amount of seawater left by receding tides is so great that evaporation no longer produces saturated solutions encrustations of algae or barnacles may also inhibit cavity enlargement in the supratidal spray zone honeycomb weathering results from a dynamic balance between the corrosive action of salt and the protective effects of endolithic microbes subtle environmental shifts may cause honeycomb cavity patterns to continue to develop to become stable or to coalesce to produce a barren surface cavity patterns produced by complex interactions between inorganic processes and biologic activity provide a geological model of self organization surface hardening is not a factor in honeycomb formation at these study sites salt weathering in coastal environments is an intermittently active process that requires particular wind and tidal conditions to provide a supply of salt water and temperature and humidity conditions that cause evaporation under these conditions salt residues may be detectable in honeycomb weathered rock but absent at other times honeycomb weathering can form in only a few decades but erosion rates are retarded in areas of the rock that contain cavity patterns relative to adjacent non honeycombed surfaces copyright 2010 john wiley sons ltd

shore platform erosion and evolution implications for cosmogenic nuclide analysis abstract determining rates and modes of shore platform development and the age of associated elements are among the greatest challenges facing rock coast researchers today these coasts generally lack dateable deposits but cosmogenic nuclide analysis cna can be applied directly to bare rock surfaces to estimate erosion rates or the time that a surface has been exposed over millennial timescales therefore this technique has the potential to revolutionize current theories on rock coast evolution and modes of development because environmental and geomorphological factors affect rates of nuclide accumulation and retention however the results of cna analysis are dependent on the validity of the theoretical models that have to be employed according to the particular application among the important assumptions that may be made are those concerned with shading tidal immersion beach sediment covers and other factors that influence rates of nuclide accumulation and with possible spatial and temporal patterns in shore platform erosion primarily by wave generated backwearing and weathering induced downwearing that reduce nuclide concentrations our lack of understanding of the factors that control these variables and in particular shore platform erosion which is the subject of this review has important implications for modelling rock coast evolution assessing the possible contribution of inheritance and dating especially by cna the occurrence of important formative events

tidal wetting and drying on shore platforms an experimental study of surface expansion and contraction laboratory experiments have been conducted to measure rock expansion and contraction induced by wetting and drying on intertidal shore platforms in eastern canada almost 800 rock cores and cubes were subjected to between 800 and 1000 tidal cycles the rocks were put into tidal simulators and inundated in de ionized water for 1 6 or 11 h of each 12 h cycle replicating conditions at the high mid and low tidal levels respectively micro erosion meter mem stations were also installed in slabs of argillite sandstone and basalt the slabs were subjected to conditions at the high mid and low tidal levels and a traversing mem was used to measure rock expansion and contraction as the slabs dried in air with variable temperature and humidity during low tide the slabs were also exposed for long periods to air with variable humidity cores and cubes often gained in weight when they absorbed or adsorbed water and retained it for periods ranging from 1 month to 1 year or more although this did not appear to be a prelude to rock breakdown tidal wetting and drying and exposure to humid air caused the argillite and basalt slabs to expand and contract by up to 0 14 and 0 04 mm respectively wetting and drying did not induce expansion or contraction of the sandstone but the sandstone did respond slightly to changes in air humidity the greatest amount of expansion and contraction was at the high tidal level in the argillite and at the mid tidal level in the basalt which is consistent with previously measured rates of downwearing

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

physical weathering of carbonate host rock by precipitation of soluble salts in caves a case study in el oron arco cave region of murcia se spain abstract the dissolution of carbonate host rock by freshwater in phreatic or vadose conditions is the most common mechanism for the formation of caves however circulation of saline solutions through carbonate materials and precipitation of soluble salts may also play an important role we studied the stable isotope composition 18o and 34s of sulfate 18o and d of structurally bound gypsum hydration water and 87sr 86sr and salinity of fluid inclusions in gypsum speleothems found in el oron arco cave cartagena se spain we suggest that physical weathering of carbonate host rock was driven by precipitation of soluble sea salts mostly gypsum and halite and this process controlled the recent geomorphological evolution of the cave the triassic carbonate host rock shows clear evidence for salt weathering including gypsum halite infillings in cracks of the bedrock mechanical spalling of the carbonate and detachment of rock fragments that lead to the formation cave voids and in situ accumulations of piles of unsorted rubble sulfur and oxygen isotopes of gypsum sulfate 3 0

micro topographic change on calcarenites grand cayman island west indies changes in micro topography as a result of varying erosion rates have been monitored on a calcarenite ridge on grand cayman island west indies using a traversing model of the micro erosion meter erosion takes place through the solution of a calcitic cement and solutional disintegration results in a rapid change of micro relief where a protective crust is present surface lowering is slower and also more uniform thus the original relative relief is maintained

thermal properties as controls on rock surface temperature maxima and possible implications for rock weathering four rock types basalt sandstone granite and chalk are examined with respect to the maximum surface temperatures which they experience when subjected to similar conditions of exposure rock temperature measurements are reported for an urban environment and for two experimental situations in which an infrared lamp is used to simulate heating under cold and hot conditions differences in rock temperatures are discussed with reference to thermal rock properties albedo specific heat capacity and thermal conductivity some natural situations are suggested in which thermal rock properties could conceivably play a role in determining the extent to which rocks would be affected by particular weathering processes

the influence of seasonal and local weather conditions on rock surface changes on the shore platform at kaikoura peninsula south island new zealand abstract a traversing micro erosion meter tmem was used to measure micro scale surface changes in a 45 cm2 area of an intertidal mudstone shore platform on kaikoura peninsula new zealand with hourly readings taken over 5 days for two seasons within 4 h either side of low tide for all monitoring events the relative height of a total of 120 co ordinates were obtained resulting in 4200 and 4800 measurements for the summer and winter seasons respectively within seasons samples were grouped according to the presence of rain or no rain significant changes were found in the micro topography with variations in temperature and among rain and no rain sample groups for both seasons in the absence of rain there were positive linear relationships between rock surface temperatures and rock surface elevations and regression analysis explained 42 3 and 46 5 of this variation for the summer y 0 098 0 004x p value 0 007 and winter y 0 007 0 012x p value

laboratory simulation of the salt weathering of schist 1 weathering of schist blocks in a seasonally wet tropical environment data describing sediment generation focusing on the temporal evolution of size gradation are required for the prediction of long term landform evolution this paper presents such data for the salt weathering of a quartz chlorite schist obtained from the ranger uranium mine in northern australia rock fragment samples are subjected to three different climate regimes 1 a dry season climate 2 a wet season climate both based on observations at the ranger site and 3 an oven drying sequence designed to test the sensitivity of the weathering process by exposing the rocks to more extreme temperatures two mgso4 salt solutions are applied one being typical of wet season runoff and the other a more concentrated solution salt solution is applied daily in the wet season experiments and once only at the beginning of the dry season experiments results of the experiments reveal four stages of weathering the kinetics of each stage are described and related to the formation of sediment of different sizes wet season climate conditions are shown to produce greater moisture variability and lead to faster weathering rates however salt concentrations in the wet season are typically lower and so when climate is combined with observed salt concentrations the dry and wet season experiments weather at approximately equal rates finally small variations in rock properties were shown to have a large impact on weathering rates leading to the conclusion that rock weathering experiments need to be carefully designed if results are to be used to help predict weathering behaviour at the landscape scale copyright 2006 john wiley sons ltd

sandstone weathering a century of research and innovation abstract a review of sandstone weathering research particularly in the past 100 years reveals a trajectory of enquiry from early description and classification of features to development of process based explanations to decreasing scales of investigation and a disparity between understanding of process es and explanations of the genesis of sandstone weathering features developments in expositions on mesoscale weathering features on sandstone surfaces are discussed demonstrating a range of approaches to weathering phenomena field based and laboratory based that must be linked to provide an explanation of observed features on a landform scale throughout the twentieth century a thematic chronology highlights certain trends in research description of forms often in arid and semi arid environments single process form models an emphasis on experimentation difficulties in measuring weathering rates and a persistent emphasis on physical causes of breakdown a new research agenda is promoted in which biodeterioration and chemical processes gain parity a holistic approach based on conceptual modeling of weathering systems gains prominence and scale issues are addressed more rigorously

corroded cobbles in southern death valley their relationship to honeycomb weathering and lake shorelines in southern death valley pits similar in morphology to honeycomb weathering herein referred to as corrosion pits occur on the surfaces of cobbles that are associated with wave produced benches the pitted cobbles include a variety of igneous metamorphic and siliciclastic rocks corrosion pits are rare to absent in limestones or dolomites pit morphology is controlled by cobble lithology in massive rocks the pits are arcuate elongate and gently tapering corrosion of laminated or foliated rocks has produced irregular more jagged pits the presence of desert varnish has strongly inhibited the corrosion process the corroded cobbles are inferred to reflect both chemical and physical weathering of rocks along pleistocene lacustrine strandlines corrosion took place through salt weathering and or heat moisture expansion processes and through chemical dissolution of selected minerals as a result of splash zone wetting and drying the ancient lake waters may have had high ph and high total dissolved solids contents the recognition of corroded cobbles may be important in the reconstruction of the position of ancient shorelines for certain types of alkaline lakes and in the reconstruction of their ancient chemistries

identifying mechanisms of shore platform erosion using structure from motion sfm photogrammetry shore platforms control wave energy transformation which in turn controls energy delivery to the cliff toe and nearshore sediment transport insight into shore platform erosion rates has conventionally been constrained at mm scales using micro erosion metres and at m scales using cartographic data on apparently slowly eroding coasts such approaches are fundamentally reliant upon long term observation to capture emergent erosion patterns where in practise timescales are short and where change is either below the resolution or saturates the mode of measurement the collection of data that enables the identification of the actual mechanisms of erosion is hindered we developed a method to monitor shore platform erosion at millimetre resolution within metre scale monitoring plots using structure from motion photogrammetry we conducted monthly surveys at 15 0 25 m2 sites distributed across the hartle loup platform in north yorkshire uk over one year we derived topographic data at 0 001 m resolution retaining a vertical precision of change detection of 0 001 m we captured a mean erosion rate of 0 528 mm yr 1 but this varied considerably both across the platform and through the year we characterised the volume and shape of eroded material the detachment volume frequency and shape distributions suggest that erosion happens primarily via removal of shale platelets we identify that the at a point erosion rate can be predicted by the distance from the cliff and the tidal level whereby erosion rates are higher closer to the cliff and at locations of higher tidal duration the size of individual detachments is controlled by local micro topography and rock structure whereby larger detachments are observed on more rough sections of the platform faster erosion rates and larger detachments occur in summer months rather than in more energetic winter conditions these results have the potential to form the basis of improved models of how platforms erode over both short and long timescales

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

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

transverse micro erosion meter measurements determining minimum sample size two transverse micro erosion meter tmem stations were installed in each of four rock slabs a slate shale basalt phyllite schist and sandstone one station was sprayed each day with fresh water and the other with a synthetic sea water solution salt water to record changes in surface elevation usually downwearing but with some swelling 100 measurements the pilot survey the maximum for the tmem used in this study were made at each station in february 2010 and then at two monthly intervals until february 2011 the data were normalized using box cox transformations and analyzed to determine the minimum number of measurements needed to obtain station means that fall within a range of confidence limits of the population means and the means of the pilot survey the effect on the confidence limits of reducing an already small number of measurements say 15 or less is much greater than that of reducing a much larger number of measurements say more than 50 by the same amount there was a tendency for the number of measurements for the same confidence limits to increase with the rate of downwearing although it was also dependent on whether the surface was treated with fresh or salt water about 10 measurements often provided fairly reasonable estimates of rates of surface change but with fairly high percentage confidence intervals in slowly eroding rocks however many more measurements were generally needed to derive means within 10 of the population means the results were tabulated and graphed to provide an indication of the approximate number of measurements required for given confidence limits and the confidence limits that might be attained for a given number of measurements

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

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

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

a morphological study of greenschist weathering on dated coastal structures south devon uk three dated structures up to 450 years in age display the effects of coastal weathering of the greenschist of which they are constructed a variety of weathering forms is present the various topographic surfaces of the structures create variation in weathering environments and consequent weathering processes and rates weathering is enhanced by direct exposure to salt bearing spray and by humid conditions and apparently limited by direct exposure to solar radiation the maximum rates of weathering on the three surfaces approximate to 0 6 mm a 1 over this period consistent with measured contemporary weathering rates for a natural surface formed by this rock type in a nearby coastal location 1997 by john wiley sons ltd