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

active thrusting and folding along the northern tien shan and late cenozoic rotation of the tarim relative to dzungaria and kazakhstan we have studied geometries and rates of late cenozoic thrust faulting and folding along the northern piedmont of the tien shan mountain belt west of urumqi where the m 8 3 manas earthquake occurred on december 23 1906 the northern range of the tien shan rising above 5000 m overthrusts a flexural foredeep filled with up to 11 000 m of sediment of the dzungarian basement our fieldwork reveals that the active thrust reaches the surface 30 km north of the range front within a 200 km long zone of neogene quaternary anticlines fault scarps are clearest across inset terraces within narrow valleys incised through the anticlines by large rivers flowing down from the range in all the valleys the scarps offset vertically the highest terrace surface by the same amount 10 2 0 7 m inferring an early holocene age 10 2 kyr for this terrace which is continuous with the largest recent fans of the piedmont yields a rate of vertical throw of 1 0 0 3mm yr on the main active thrust at the surface a quantitative morphological analysis of the degradation of terrace edges that are offset by the thrust corroborates such a rate and yields a mass diffusivity of 5 5 2 5 m 2 kyr a rather fresh surface scarp 0 8 0 15 m high that is unlikely to result from shallow earthquakes with 6 m 7 in the last 230 years is visible at the extremities of the main fold zone we associate this scarp with the 1906 manas earthquake and infer that a structure comprising a deep basement ramp under the range gently dipping flats in the foreland and shallow ramps responsible for the formation of the active fault propagation anticlines could have been activated by that earthquake if so the return period of a 1906 type event would be 850 380 years the small size of the scarp for an earthquake of this magnitude suggests that a large fraction of the slip at depth 2 3 is taken up by incremental folding near the surface comparable earthquakes might activate flat detachments and ramp anticlines at a distance from the front of other rising quaternary ranges such as the san gabriel mountains in california or the mont blanc aar massifs in the alps we estimate the finite cenozoic shortening of the folded dzungarian sediments to be of the order of 30 km and the cenozoic shortening rate to have been 3 1 5 mm yr assuming comparable shortening along the tarim piedmont and minor additional active thrusting within the mountain belt we infer the rate of shortening across the tien shan to be at least 6 3 mm yr at the longitude of manas 85 5 e a total shortening of 125 30 km is estimated from crustal thickening assuming local airy isostatic equilibrium under the same assumption serial n s sections imply that cenozoic shortening across the belt increases westwards to 203 50 km at the longitude of kashgar 76 e as reflected by the westward increase of the width of the belt this strain gradient implies a clockwise rotation of tarim relative to dzungaria and kazakhstan of 7 2 5 around a pole located near the eastern extremity of the tien shan west of hami 96 e 43 5 n comparable to that revealed by paleomagnetism between tarim and dzungaria 8 6 8 7 a 6 mm yr rate of shortening at the longitude of manas would imply a rate of rotation of 0 45 m y and would be consistent with a shortening rate of 12 mm yr north of kashgar taking such values to be representative of late cenozoic rates would place the onset of reactivation of the tien shan by the india asia collision in the early to middle miocene 16 22 9 m y in accord with the existence of particularly thick late neogene and quaternary deposits such reactivation would thus have started much later than the collision roughly at the time of the great mid miocene changes in tectonic regimes denudation and sedimentation rates observed in southeast asia the himalayas and the bay of bengal and of the correlative rapid change in seawater sr isotopic ratio 20 to 15 ma like these other changes the rise of the tien shan might be a distant consequence of the end of indochina s escape

rock warming and drying under simulated intertidal conditions part ii weathering and biological influences on evaporative cooling and near surface micro climatic conditions as an example of biogeomorphic ecosystem engineering the way in which rocks and engineering materials heat up and dry out in the intertidal zone is of relevance to both weathering and ecology these behaviours can be measured in the laboratory under controlled conditions designed to replicate those occurring in the field previous studies have demonstrated differences in thermal behaviours between rock types and through time as a result of soiling in terrestrial environments but the influence of weathering and colonization on rock behaviours in the intertidal zone has not been previously assessed we measured the warming and drying of blocks of rock limestone and granite and marine concrete during low tide events simulated in the laboratory before and after a period of exposure eight months on rock platforms in cornwall uk as well as differences between the material types temperatures of control unexposed and field exposed blocks differed in the order of 1 to 2 c drying behaviours were also different after field exposure differences during the first few hours of exposure to air and heat were attributed to discolouration and albedo effects over longer periods of time changes in the availability of near surface pore water as a result of micro scale bioerosion of limestone and the development of bio chemical crusts on marine concrete observed using scanning electron microscopy sem are suggested as mechanisms enhancing and reducing respectively the efficiency of evaporative cooling the retention of moisture by epilithic biofilms may also influence thermal and drying behaviours of granite these observations represent one of the first examples of cross scalar biogeomorphic linkages in the intertidal zone the significance of the results for the subsequent efficiency of weathering and near surface micro climatic conditions experienced by colonizing organisms is discussed the involvement of microorganisms in the creation of more or less ecologically stressful conditions through the alteration of substratum geomorphic properties and behaviours is suggested as an example of biogeomorphic ecosystem engineering copyright 2011 john wiley sons ltd

limestone and the problem of radiocarbon dating of land snail shell carbonate in order to test the role of limestone in producing anomalously old radiocarbon ages in land snail shells 14 c analyses were performed on shell carbonate of modern land snails from limestone and nonlimestone areas of jamaica no anomaly was found in snails from the nonlimestone area implying that such material is suitable for radiocarbon dating snails from limestone areas produced variable anomalies of as much as 3 120 yr due to incorporation of 14 c free limestone into shell carbonate all rock scraping snails and most leaf litter feeding snails from limestone areas showed anomalous 14 c contents because of the variability in 14 c content even within species no standard correction factor for limestone anomaly can be applied however dating error can be minimized by selecting ecologically appropriate species or by comparison of analyses of several fossil species within a stratum to their modern counterparts

late quaternary slip rates across the central tien shan kyrgyzstan central asia 1 slip rates across active faults and folds show that late quaternary faulting is distributed across the central tien shan not concentrated at its margins nearly every intermontane basin contains neogene and quaternary syntectonic strata deformed by holocene north south shortening on thrust or reverse faults in a region that spans two thirds of the north south width of the central tien shan slip rates on eight faults in five basins range from 0 1 to 3 mm yr fault slip rates are derived from faulted and folded river terraces and from trenches radiocarbon optically stimulated luminescence and thermoluminescence ages limit ages of terraces and aid in their regional correlation monte carlo simulations that sample from normally distributed and discrete probability distributions for each variable in the slip rate calculations generate most likely slip rate values and 95 confidence limits faults in basins appear to merge at relatively shallow depths with crustal scale ramps that underlie mountain ranges composed of pre cenozoic rocks the sum and overall pattern of late quaternary rates of shortening are similar to current rates of north south shortening measured using global positioning system geodesy this similarity suggests that deformation is concentrated along major fault zones near range basin margins such faults separated by rigid blocks accommodate most of the shortening in the upper crust index terms 8107 tectonophysics continental neotectonics 9320 information related to geographic region asia 8010 structural geology fractures and faults

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

the subtidal morphology of microtidal shore platforms and its implication for wave dynamics on rocky coasts abstract the subtidal portions of shore platforms are important geomorphic features as they can modify deep water wave energy before it impacts the intertidal platform edge in this study an integrated marine and terrestrial aerial lidar dataset is used to analyse the morphology of the subtidal portion of shore platforms semi horizontal intertidal platforms on an 85 km along stretch of microtidal open ocean rocky coast in victoria australia are investigated and described quantitatively three distinct types of subtidal morphology occur i a steep cliff with a mean slope of 8 18 ii a gently sloping ramp with a mean slope of

new empirical relationships among magnitude rupture length rupture width rupture area and surface displacement source parameters for historical earthquakes worldwide are compiled to develop a series of empirical relationships among moment magnitude m surface rupture length subsurface rupture length downdip rupture width rupture area and maximum and average displacement per event the resulting data base is a significant update of previous compilations and includes the additional source parameters of seismic moment moment magnitude subsurface rupture length downdip rupture width and average surface displacement each source parameter is classified as reliable or unreliable based on our evaluation of the accuracy of individual values only the reliable source parameters are used in the final analyses in comparing source parameters we note the following trends 1 generally the length of rupture at the surface is equal to 75 of the subsurface rupture length however the ratio of surface rupture length to subsurface rupture length increases with magnitude 2 the average surface displacement per event is about one half the maximum surface displacement per event and 3 the average subsurface displacement on the fault plane is less than the maximum surface displacement but more than the average surface displacement thus for most earthquakes in this data base slip on the fault plane at seismogenic depths is manifested by similar displacements at the surface log linear regressions between earthquake magnitude and surface rupture length subsurface rupture length and rupture area are especially well correlated showing standard deviations of 0 25 to 0 35 magnitude units most relationships are not statistically different at a 95 significance level as a function of the style of faulting thus we consider the regressions for all slip types to be appropriate for most applications regressions between magnitude and displacement magnitude and rupture width and between displacement and rupture length are less well correlated and have larger standard deviation than regressions between magnitude and length or area the large number of data points in most of these regressions and their statistical stability suggest that they are unlikely to change significantly in response to additional data separating the data according to extensional and compressional tectonic environments neither provides statistically different results nor improves the statistical significance of the regressions regressions for cases in which earthquake magnitude is either the independent or the dependent parameter can be used to estimate maximum earthquake magnitudes both for surface faults and for subsurface seismic sources such as blind faults and to estimate the expected surface displacement along a fault for a given size earthquake

evaporative moisture loss from heterogeneous stone material environment interactions during drying abstract the complexities of evaporation from structurally and mineralogically heterogeneous sandstone locharbriggs sandstone are investigated through a laboratory based experiment in which a variety of environmental conditions are simulated data reported demonstrate the significance of material environment interactions on the spatial and temporal variability of evaporative dynamics evaporation from porous stone is determined by the interplay between environmental material and solution properties which govern the rate and mode by which water is transmitted to and subsequently removed from an evaporating surface initially when the stone is saturated evaporation is characterized by high rates of moisture loss primarily controlled by external atmospheric conditions however as drying progresses eventually the hydraulic continuity between the stone surface and subsurface is disrupted with recession of the drying front and a decrease in evaporation rates which become reliant on the ability of the material to transport water vapour to the block surface pore size distribution and connectivity as well as other material properties control the timing of each stage of evaporation and the nature of the transition these experimental data highlight the complexity of evaporation demonstrating that different regions of the same stone can exhibit varying moisture dynamics during drying and that the rate and nature of evaporative loss differs under different environmental conditions the results identify the importance of material environment interactions during drying and that stone micro environmental conditions cannot be inferred from ambient data alone these data have significance for understanding the spatial distribution of stone surface weathering related morphologies in both the natural and built environments where mineralogical and or structural heterogeneity creates differences in moisture flux and hence variable drying rates such differences may provide a clearer explanation for the initiation and subsequent development of complex weathering responses where areas of significant deterioration can be found alongside areas that exhibit little or no evidence of surface breakdown

integration of paleoseismic data from multiple sites to develop an objective earthquake chronology application to the weber segment of the wasatch fault zone utah we present a method to evaluate and integrate paleoseismic data from multiple sites into a single objective measure of earthquake timing and recurrence on discrete segments of active faults we apply this method to the weber segment ws of the wasatch fault zone using data from four fault trench studies completed between 1981 and 2009 after systematically reevaluating the stratigraphic and chro nologic data from each trench site we constructed time stratigraphic oxcal models that yield site probability density functions pdfs of the times of individual earth quakes we next qualitatively correlated the site pdfs into a segment wide earthquake chronology which is supported by overlapping site pdfs large per event displace ments and prominent segment boundaries for each segment wide earthquake we computed the product of the site pdf probabilities in common time bins which emphasizes the overlap in the site earthquake times and gives more weight to the narrowest best defined pdfs the product method yields smaller earthquake timing uncertainties compared to taking the mean of the site pdfs but is best suited to earth quakes constrained by broad overlapping site pdfs we calculated segment wide earthquake recurrence intervals and uncertainties using a monte carlo model five surface faulting earthquakes occurred on the ws at about 5 9 4 5 3 1 1 1 and 0 6 ka with the exception of the 1 1 ka event we used the product method to define the earthquake times the revised ws chronology yields a mean recurrence interval of 1 3 kyr 0 7 1 9 kyr estimated two sigma 2 range based on interevent recurrence these data help clarify the paleoearthquake history of the ws including the important question of the timing and rupture extent of the most recent earthquake and are essential to the improvement of earthquake probability assessments for the wasatch front region

morphological dating of cumulative reverse fault scarps examples from the gurvan bogd fault system mongolia summary we relate reverse fault scarp morphology formed by several earthquake dislocations to the average deformation rate using a morphological dating model based on a diffusion analogue of erosion our scarp degradation model includes diffusive erosion during the interseismic period the gravitational collapse of the coseismic fault scarp just after formation and the variation of the surface rupture location interactions between thrusting and geomorphic processes acting on scarp morphology are analysed along the gurvan bogd range in mongolia four main processes acting on scarp morphology were distinguished i gravitational collapse of the frontal scarp resetting the diffusive scarp if fault offsets are big and faulting is localized 2 progressive erosion of the fault scarp during the interseismic period 3 folding associated with the frontal thrust and backthrusts 4 competing alluvial deposition on mountain piedmont slopes and abrasion of the fault scarp by wash processes the growth of cumulative reverse fault scarps is suppressed when they are located in the outwash of major drainage basins they can grow higher in distance from major catchment discharges the modelling suggests that the morphology of the scarp and its apparent degradation stage depend on the parameters controlling the amount of frontal collapse the magnitude of coseismic offsets the dip of the fault near the surface and the step distance between faults folding associated with thrusting creates a convexity on the upper part of the scarp and increases its height the comparison of different scarp profiles suggests that folding leads to an overestimate of the morphological age we estimate a diffusion coefficient at 3 3 1 7 m 2 ka l morphological ages calculated with our model confirm that slip rate along reverse faults of the gurvan bogd range has not been constant over the last 100 ka

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

analysis of relationships between micro topography and short and long term erosion rates on shore platforms at kaikoura peninsula south island new zealand using long term data sets of erosion rates for the shore platform at kaikoura it is possible to assess the relationships between erosion rates over two and ten years erosion rates do not tend to vary significantly between the two measurement periods using linear regression analysis a difference in the nature of topographic change is identified between mudstone and limestone shore platforms the mudstone platforms show a consistent mode of topographic change parallel retreat or smoothing between the short and long terms limestone shore platforms show no consistent mode of topographic change it is suggested that the consistent behaviour of the mudstone platforms occurs because the mudstone surface is responding as a single unit at this scale of measurement erosion rates tend to increase with distance from the seaward edge of the platforms and this may reflect the increasing significance of wetting and drying cycles as well as the increasing mix of erosional processes as sub aerial processes increase in importance this changing mix of erosional processes may also explain the variations in gradient coefficients between short and long term erosion rates with distance from the seaward edge of the platforms

bioprotection and disturbance seaweed microclimatic stability and conditions for mechanical weathering in the intertidal zone as well as their destructive roles plants animals and microorganisms contribute to geomorphology and ecology via direct and indirect bioprotection which can reduce weathering and erosion for example indirect bioprotection can operate via biotic influences on microclimate whereby physical decay processes associated with fluctuations in temperature and moisture salt crystallization thermal fatigue and wetting drying are limited in the intertidal zone the spatial and temporal distribution of macroalgae seaweeds is patchy related to physical and ecological conditions for colonization and growth and the nature and frequency of natural and anthropogenic disturbance we examined the influence of seaweed canopies fucus spp on near surface microclimate and by implication on conditions for mechanical rock decay and under canopy ecology monitoring on hard artificial coastal structures in south west england uk built from limestone and concrete showed that both the range and maxima of daily summertime temperatures were significantly lower by an average of 56 and 25 respectively in areas colonized by seaweed compared to experimentally cleared areas short term microclimatic variability minutes hours was also significantly reduced by an average of 78 for temperature and 71 for humidity under algal canopies during low tide events using seaweed as an example we develop a conceptual model of the relationship between biological cover and microclimate in the intertidal zone disturbance events that remove or drastically reduce seaweed cover mediate shifts between relatively stable and unstable states with respect to mechanical decay and ecological stress associated with heat and desiccation in urban coastal environments where disturbance may be frequent facilitating the establishment and recovery of canopy forming species on rocks and engineered structures could enhance the durability of construction materials as well as support conservation planning and policy targets for biodiversity enhancement

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

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

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

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

neogene to quaternary broken foreland formation and sedimentation dynamics in the andes of nw argentina 25 s 1 the northwest argentine andes constitute a premier natural laboratory to assess the complex interactions between isolated uplifts orographic precipitation gradients and related erosion and sedimentation patterns here we present new stratigraphic observations and age information from intermontane basin sediments to elucidate the neogene to quaternary shortening history and associated sediment dynamics of the broken salta foreland this part of the andean orogen which comprises an array of basement cored range uplifts is located at 25 s and lies to the east of the arid intraorogenic altiplano puna plateau in the salta foreland spatially and temporally disparate range uplift along steeply dipping inherited faults has resulted in foreland compartmentalization with steep basin to basin precipitation gradients sediment architecture and facies associations record a three phase 10 5 and 2 ma east directed yet unsystematic evolution of shortening foreland fragmentation and ensuing changes in precipitation and sediment transport the provenance signatures of these deposits reflect the trapping of sediments in the intermontane basins of the andean hinterland as well as the evolution of a severed fluvial network present day moisture supply to the hinterland is determined by range relief and basin elevation the conspiring effects of range uplift and low rainfall help the entrapment and long term storage of sediments ultimately raising basin elevation in the hinterland which may amplify aridification in the orogen interior

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

the multidecadal spatial pattern of erosion on sandstone shore platforms in south eastern australia abstract knowledge of the spatial pattern of erosion on shore platforms is needed to better understand their evolution the long term spatial and temporal variation of downwearing remains difficult to interpret from erosion data commonly collected over 1 3 years of monitoring we report erosion data recorded with a micro erosion meter mem over 40 years 1979 2019 on sandstone shore platforms in a micro tidal environment along the otway coast victoria australia this well preserved monitoring network 43 out of 44 original mem sites allowed a detailed investigation over a multidecadal timescale not previously considered over 40 years the mean erosion rate was 0 25 mm yr this value was statistically similar to erosion rates calculated over 2 year 0 32 mm yr and 32 year 0 26 mm yr periods in the vertical plane two significant but opposite relationships between elevation and erosion rates were displayed in the central intertidal zone there was also a peak in the erosion rate near mean higher high water level this spatial pattern was strongly associated with wetting and drying controlled by tides and waves at elevations lower than mean higher low water downwearing rates were one or two orders of magnitude lower than the average rate of the entire platform the low erosion rates may be caused by the longer wetting condition of surfaces at lower elevation fast erosion rates were recorded in the upper intertidal zone where the bedrock was only inundated by spring high tides or storm waves salt weathering may be the primary mechanism but the effect of thermal weathering cannot be neglected at higher elevation based on the experience from the near complete mem network in the study area suggestions were provided to extend the longevity of monitoring network for future long term erosion records on shore platforms

the dzhungarian fault late quaternary tectonics and slip rate of a major right lateral strike slip fault in the northern tien shan region the dzhungarian strike slip fault of central asia is one of a series of long nw se right lateral strike slip faults that are characteristic of the northern tien shan region and extends over 300 km from the high mountains into the kazakh platform our field based and satellite observations reveal that the dzhungarian fault can be characterized by three 100 km long sections based on variation in strike direction through morphological analysis of offset streams and alluvial fans and through optically stimulated luminescence dating we find that the dzhungarian fault has a minimum average late quaternary slip rate of 2 2 0 8 mm yr and accommodates n s shortening related to the india eurasia collision this shortening may also be partly accommodated by counterclockwise rotation about a vertical axis evidence for a possible paleo earthquake rupture indicates that earthquakes up to at least mw 7 can be associated with just the partitioned component of reverse slip on segments of the central section of the fault up to 30 km long an event rupturing longer sections of the dzhungarian fault has the potential to generate greater magnitude earthquakes mw 8 however long time periods e g thousands of years are expected in order to accumulate enough strain to generate such earthquakes

postseismic stress transfer explains time clustering of large earthquakes in mongolia abstract three m 8 earthquakes have occurred in mongolia during a 52 year period 1905 1957 since these earthquakes were well separated in space 400 km the coseismic stress change is far too low 0 001 bar to explain mutual earthquake triggering by contrast postseismic relaxation gradually causes a significant stress change 0 1 0 9 bar over large distances using a spring slider model to simulate earthquake interaction we find that viscoelastic stress transfer may be responsible for the earthquake time clustering observed in active tectonic areas therefore revealing postseismic strain by satellite geodesy and modeling earthquake clusters could improve our understanding of earthquake occurrence especially in zones where large earthquakes have already struck in past decades

a quantitative determination of the effect of moisture on purple mudstone decay in southwestern china aims the moisture condition is well known to be a key factor that apparently influences rock decay but little is known about the quantitative correlations between a rock s decay rate and its moisture content which makes it difficult to quantitatively predict the rate of rock decay under varied moisture conditions thus in this paper our aim is to observe the decay rates of various purple mudstones with different moisture contents and to develop an equation to calculate the decay rate

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

active intracontinental transpressional mountain building in the mongolian altai defining a new class of orogen abstract mountain ranges that are actively forming around the western and northern perimeter of the indo eurasia collisional deformational field such as the mongolian altai comprise a unique class of intracontinental intraplate transpressional orogen with structural and basinal elements that are distinct from contractional and extensional orogens late cenozoic uplift and mountain building in the mongolian altai is dominated by regional scale dextral strike slip faults that link with thrust and oblique slip faults within a 300 km wide deforming belt sandwiched between the more rigid junggar basin block and hangay precambrian craton dominant orogenic elements in the mongolian altai include double restraining bends terminal restraining bends partial restraining bends single thrust ridges thrust ridges linked by strike slip faults and triangular block uplifts in areas of conjugate strike slip faults the overall pattern is similar to a regional strike slip duplex array however the significant amount of contractional and oblique slip displacement within the range and large number of historical oblique slip seismic events renders the term transpressional duplex more accurate intramontane and range flanking basins can be classified as ramp basins half ramp basins open sided thrust basins pull apart basins and strike slip basins neither a classic fold and thrust orogenic wedge geometry nor a bounding foredeep exists the manner in which upper crustal transpressional deformation is balanced in the lower crust is unknown however crustal thickening by lower crustal inflation and northward outflow of lower crustal material are consistent with existing geological and geodetic data and could account for late cenozoic regional epeirogenic uplift in the russian altai and sayan regions

mechanics and erosion of basement cored uplift provinces 1 basement cored uplift provinces are often characterized by high angle reverse faulting along preexisting crustal heterogeneities which may greatly affect the mechanics of deformation and the coupling between erosion and orogenic structure herein we construct a coupled deformation erosion model to understand the mechanics and erosion of mountain belts in which the spatial distribution of deformation is largely influenced by the presence of preexisting high angle faults in this case deformation is accommodated along and topography is built above these structures this topographic loading leads to increasing lithostatic stresses beneath these regions as a result active deformation may migrate to frictionally stronger structures in adjacent regions where lithostatic loading is lower the migration of deformation to such nearby structures depends on the hubbert rubey pore fluid pressure ratio of the crust the orientations of the frictionally weaker and stronger preexisting faults 1 and 2 respectively the friction coefficients b1 and b2 and hubbert rubey fluid pressure ratios b1 and b2 of these faults and the surface slope of the topography above the frictionally weaker structure assuming zero surface slope above the frictionally stronger structure in general we found that for a given and 1 as b1 increases b1 b2 increases and 2 decreases the value of b2 required to force deformation to migrate increases however as erosional processes lead to decreasing surface slopes deformation will be inhibited from migrating to frictionally stronger structures in adjacent regions our model results may help to explain some aspects of the deformation observed and the possible correlation between precipitation and the migration of deformation within these tectonic provinces

repeated large magnitude earthquakes in a tectonically active low strain continental interior the northern tien shan kyrgyzstan the northern tien shan of kyrgyzstan and kazakhstan has been affected by a series of major earthquakes in the late 19th and early 20th centuries to assess the significance of such a pulse of strain release in a continental interior it is important to analyze and quantify strain release over multiple time scales we have undertaken paleoseismological investigations at two geomorphically distinct sites panfilovkoe and rot front near the kyrgyz capital bishkek although located near the historic epicenters both sites were not affected by these earthquakes trenching was accompanied by dating stratigraphy and offset surfaces using luminescence radiocarbon and 10be terrestrial cosmogenic nuclide methods at rot front trenching of a small scarp did not reveal evidence for surface rupture during the last 5000 years the scarp rather resembles an extensive debris flow lobe at panfilovkoe we estimate a late pleistocene minimum slip rate of 0 2 0 1 mm a averaged over at least two probably three earthquake cycles dip slip reverse motion along segmented moderately steep faults resulted in hanging wall collapse scarps during different events the most recent earthquake occurred around 3 6 1 3 kyr ago 1 with dip slip offsets between 1 2 and 1 4 m we calculate a probabilistic paleomagnitude to be between 6 7 and 7 2 which is in agreement with regional data from the kyrgyz range the morphotectonic signals in the northern tien shan are a prime example of deformation in a tectonically active intracontinental mountain belt and as such can help understand the longer term coevolution of topography and seismogenic processes in similar structural settings worldwide

great earthquakes in low strain rate continental interiors an example from se kazakhstan the lepsy fault of the northern tien shan se kazakhstan extends e w 120 km from the high mountains of the dzhungarian ala tau a subrange of the northern tien shan into the low lying kazakh platform it is an example of an active structure that connects a more rapidly deforming mountain region with an apparently stable continental region and follows a known palaeozoic structure field based and satellite observations reveal an 10 m vertical offset exceptionally preserved along the entire length of the fault geomorphic analysis and age control from radiocarbon and optically stimulated luminescence dating methods indicate that the scarp formed in the holocene and was generated by at least two substantial earthquakes the most recent event dated to sometime after 400 years b p is likely to have ruptured the entire 120 km fault length in a m w 7 5 8 2 earthquake the lepsy fault kinematics were characterized using digital elevation models and high resolution satellite imagery which indicate that the predominant sense of motion is reverse right lateral with a fault strike dip and slip vector azimuth of 110 50 s and 317 343 respectively which is consistent with predominant n s shortening related to the india eurasia collision in light of these observations and because the activity of the lepsy fault would have been hard to ascertain if it had not ruptured in the recent past we note that the absence of known active faults within low relief and low strain rate continental interiors does not always imply an absence of seismic hazard

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

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

inherited strike slip faults as an origin for basement cored uplifts example of the kungey and zailiskey ranges northern tian shan 1 basement cored uplifts bounded by steeply dipping reverse faults are mechanically difficult to explain reactivation of strike slip faults that aid the formation of new high angle reverse faults in the surrounding crust may provide one origin for these structures this hypothesis is explored by examining the late miocene to quaternary evolution of the kungey and zailiskey ranges in the northern tian shan these ranges are cored by the kemin chilik fault kcf an inherited paleozoic structure with sinistral separation of basement terranes range growth in response to northward propagation of the tian shan has taken place along a network of steeply dipping reverse and oblique slip faults surrounding the kcf deformation of a low relief unconformity separating neogene strata from paleozoic basement records structural growth in response to fault slip deformed river terraces surrounding the ranges are correlated to a well preserved chronosequence in the southern kungey range cosmogenic10be dating of this chronosequence combined with offset measurements yields slip rates ranging from 0 07 to 0 37 mm yr for dip slip faults and 1 1 to 1 5 mm yr for strike slip faults late quaternary activity in the kungey zailiskey ranges is consistent with the longer term outward stepping pattern of range growth based on cross sections constrained from the folded unconformity surface deformed neogene strata and quaternary terraces faults building the kungey range are inferred to steepen at depth and emanate from a shear zone co located with the reactivated kcf this geometry is consistent with a slip partitioned system developed by an obliquely slipping reactivated fault at depth

comparison of morphological dating models for cumulative reverse fault scarps 1 degradation morphology of scarps can be used to estimate the age of an episode of uplift linear diffusion models for slope degradation provide analytical solutions relying on simplified geometry and kinematics in this paper we evaluate to what extent such models can be applied to date cumulative reverse fault scarps by comparing their predicted degradation coefficients with those of a more realistic numerical model two analytical models with increasing complexity have been considered the cu and iu models represent the morphological evolution of a single vertical fault at a constant rate of uplift and that of a vertical fault shifting incrementally respectively synthetic data are generated by a numerical model accounting for reverse faulting linear diffusion and gravity controlled collapse we show that for cumulative reverse faulting without folding approximated models neglecting fault dip and gravitational collapse lead to valid estimates of the degradation coefficient in a lot of cases because gravitational collapse and reverse faulting are competitive geomorphic processes we provide estimates of the shifts expected on the degradation coefficient according to neglected processes

the unsteady nature of sea cliff retreat due to mechanical abrasion failure and comminution feedbacks sea cliff retreat is often linked to large waves heavy precipitation and seismic events but the specific operative mechanics have not been well constrained in particular what is the role of mechanical abrasion by beach sediments in cliff platform evolution and how does it relate to the episodic nature of cliff retreat observed at certain locations here we present a simple numerical model of sea cliff retreat that incorporates mechanical abrasion of a basal notch threshold controlled failure of the cantilevered block and a feedback mechanism wherein retreat is dependent on the rate of sediment comminution within the surf zone using shore platform and cliff characteristics found in two coastal settings the central california coast and the english north sea coast the model produces retreat rates comparable to those observed via field measurements the highest retreat rates coincide with the steepest shore platforms and increasing wave height steeper platforms promote wave access to the cliff toe and correspondingly the receding cliff face produces additional accommodation space for the platform beach preserving the erosive efficacy of the beach sediments when exposed to energetic wave forcing the slope of the inner platform segment controls retreat rates for concave platforms whereas the slope of the outer platform segment exerts greater control for convex platforms platform beaches approached a long term dynamic equilibrium on the concave profiles leading to more consistent and steady retreat platform beaches were ephemeral on convex profiles mirroring observed sand wave ord migration on the holderness coast uk these findings agree with previous field observations and support mechanical abrasion as a viable cause of temporal heterogeneity in cliff retreat rate for both coastlines

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

rock protecting seaweed experimental evidence of bioprotection in the intertidal zone biogeomorphological processes are an important component of dynamic intertidal systems on rocky shores the direct contribution of microorganisms plants and animals to weathering and erosion is well known there is also increasing evidence that organisms can alter rock breakdown indirectly by moderating temperature and moisture regimes at the rock air interface these influences have been purported to represent mechanisms of bioprotection by buffering microclimatic fluctuations associated with weathering processes such as wetting and drying and salt crystallization however virtually nothing has been done to test whether microclimatic buffering translates to differences in actual rock breakdown rates here we report a preliminary laboratory experiment to assess how an artificial canopy chosen to represent seaweed affects mechanical rock breakdown using a simplified and accelerated thermal regime based on field data from a rocky shore platform in southern england uk we find that breakdown mineral debris release of mudstone covered with a canopy is reduced by as much as 79 relative to bare rock after around 100 thermal cycles reduction in rock surface hardness measured using an equotip device was also greater for bare rock 17 compared to covered rock 10 over this period measurements of salt crystal formation indicate that the mechanism driving these differences was a reduction in the frequency of crystallization events via moisture retention and shading of the rock surface copyright 2015 john wiley sons ltd

gps velocity field for the tien shan and surrounding regions 1 measurements at 400 campaign style gps points and another 14 continuously recording stations in central asia define variations in their velocities both along and across the kyrgyz and neighboring parts of tien shan they show that at the longitude of kyrgyzstan the tarim basin converges with eurasia at 20 2 mm yr nearly two thirds of the total convergence rate between india and eurasia at this longitude this high rate suggests that the tien shan has grown into a major mountain range only late in the evolution of the india eurasia collision most of the convergence between tarim and eurasia within the upper crust of the tien shan presumably occurs by slip on faults on the edges of and within the belt but 1 3 mm yr of convergence is absorbed farther north at the dzungarian alatau and at a lower rate with the kazakh platform to the west the tarim basin is thrust beneath the tien shan at 4 7 mm yr with respect to eurasia the ferghana valley rotates counterclockwise at 0 7 myr 1 about an axis at the southwest end of the valley thus gps data place a bound of 4 mm yr on the rate of crustal shortening across the chatkal and neighboring ranges on the northwest margin of the ferghana valley and they limit the present day slip rate on the right lateral talas ferghana fault to less than 2 mm yr gps measurements corroborate geologic evidence indicating that the northern margin of the pamir overthrusts the alay valley and require a rate of at least 10 and possibly 15 mm yr

uncharted seismic risk the potential for earthquakes along the plate boundaries has been mapped with reasonable success our attention should now focus on the threat posed by unanticipated quakes located in the continental interiors

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

aerodynamic stability and turbulent sensible heat flux over a melting ice surface the greenland ice sheet the turbulent sensible heat flux to a melting ice surface is calculated from wind speed and air temperature at 2 m over the ice surface assuming a certain wind profile with the appropriate surface roughness the aerodynamic stability of the boundary layer over melting ice is examined by comparing sensible heat fluxes for logarithmic and log linear wind profiles where the logarithmic profile is strictly valid only for neutral conditions increasing stability reduces the sensible heat flux to the glacier surface and introduces a non linear relation between heat flux and air temperature the stability effect is greatest at low wind speeds and fairly small at the high wind speeds that are common over the ice sheet earlier estimates of ablation by energy balance modelling may be too large due to neglect of stability but this was almost offset by using a surface roughness that was too small the log linear wind profile should be used in future energy balance models to take account of stability but more research is needed on the parameters of the profile as well as on the surface roughness

rock warming and drying under simulated intertidal conditions part i experimental procedures and comparisons with field data the wetting drying and warming cooling behaviours of rock and stone are known to influence the nature and rate of weathering the way materials warm up and dry out also influences their suitability as biological substrata while rock thermal behaviours have been measured under controlled laboratory conditions previous experiments have largely been restricted to terrestrial simulations due to practical constraints where efforts have been made to simulate intertidal conditions expansion and contraction of rocks or rates of breakdown i e sediment production and weight loss have been measured while detailed observations of thermal and drying behaviours have rarely been made a simple semi automated procedure is described that enabled measurement of surface temperatures and desorption evaporative water loss for different material types rock and concrete under simulated semidiurnal tide conditions some preliminary results are presented illustrating the types of data that were obtained and comparisons are made with temperature data collected on a rock platform in the uk to assess the ability of the procedure to adequately represent field conditions copyright 2011 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

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

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

rock coast geomorphology recent advances and future research directions there have been considerable advances in rock coast research in the past decade as measured in terms of the number of active researchers and in the number of research papers being produced this review although not exhaustive highlights many of the improvements that have been made in our ability to identify and measure the processes shaping rock coasts at a range of spatial and temporal scales we review how researchers are experimenting with new techniques grappling with quantifying the effects of multiple processes on resultant landforms and exploring how well rock coast systems relate to wider geomorphological and earth science debates recent research including those in this special issue aptly demonstrate the scientific benefits that can be accrued by studying rock coasts at a variety of spatial and temporal scales by considering the effect of the wide range of processes that operate on them and by the application of new measurement techniques and approaches despite these advances there is ample scope for future research which could profit from increasing collaboration with other coastal geomorphologists and allied earth science disciplines in order to identify and quantify linkages between rock coasts and other coastal systems it is also important that new research considers how rock coasts will respond to extreme events and to risks associated with changing climate and to how rock coast geomorphology might contribute beyond coastal science to wider debates in theoretical geomorphology

thermochronologic insight into late cenozoic deformation in the basement cored terskey range kyrgyz tien shan 1 basement cored ranges formed by reverse faulting within intracontinental mountain belts are often composed of poly deformed lithologies geological data capable of constraining the timing magnitude and distribution of the most recent deformational phase are usually missing in such ranges in this paper we present new low temperature thermochronological and geological data from a transect through the basement cored terskey range located in the kyrgyz tien shan using these data we are able to investigate the range s late cenozoic deformation for the first time displacements on reactivated faults are constrained and deformation of thermochronologically derived structural markers is assessed these structural markers postdate the earlier deformational phases providing the only record of cenozoic deformation and of the reactivation of structures within the terskey range overall these structural markers have a southern inclination interpreted to reflect the decreasing inclination of the reverse fault bounding the terskey range our thermochronological data are also used to investigate spatial and temporal variations in the exhumation of the terskey range identifying a three stage cenozoic exhumation history 1 virtually no exhumation in the paleogene 2 increase to slightly higher exhumation rates at 26 20 ma and 3 significant increase in exhumation starting at 10 ma

depositional processes in large scale debris flow experiments this study examines the depositional process and characteristics of deposits of large scale experimental debris flows to 15 m3 composed of mixtures of gravel to 32 mm sand and mud the experiments were performed using a 95 m long 2 m wide debris flow flume that slopes 31 following release experimental debris flows invariably developed numerous shallow 10 cm deep surges sediment transported by surges accumulated abruptly on a 3 runout slope at the mouth of the flume deposits developed in a complex manner through a combination of shoving forward and shouldering aside previously deposited debris and through progressive vertical accretion progressive accretion by the experimental flows is contrary to commonly assumed en masse sedimentation by debris flows despite progressive sediment emplacement deposits were composed of unstratified accumulations of generally unsorted debris hence massively textured poorly sorted debris flow deposits are not emplaced uniquely en masse the depositional

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

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

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

relatively recent construction of the tien shan inferred from gps measurements of present day crustal deformation rates the tien shan a high seismically active intracontinental mountain belt 1 000 2 000 km north of the himalaya has grown as a result of india s collision with asia1 the crustal shortening 200 50 km refs 2 3 and thickening that gave rise to the tien shan accommodates only a small fraction of india s total penetration into asia 2 000 3 000km and the temporal relationship of deformation in this belt to the india asia collision remains unclear here we report geodetic measurements of the tien shan using the global positioning system gps that indicate that the current crustal shortening rate is nearly half of india s convergence rate with eurasia in this area4 we infer a total shortening rate for the tien shan of 20 mm yr 1 which is approximately twice that inferred previously from the extrapolation of slip rates in the holocene3 and earthquake induced displacements during this century5 suggesting that the rate of mountain building in this region has accelerated several fold since the onset of collision 50 55 myr ago6 7 if as we argue the current shortening rate can be extrapolated to geological timescales then our results suggest that most of the tien shan has been constructed during the past 10 myr perhaps in response to an increased horizontal force following an abrupt rise of the tibetan plateau8 9

modelling tidal notch formation by wetting and drying and salt weathering abstract the formation and morphology of marine notches formed by tidal wetting and drying and salt weathering was modelled for 6 micro to megatidal environments the model used published tidal elevation dependent weathering and erosional data from 1 to 3 year experiments conducted on more than 2000 sandstone argillite and basalt samples from eastern canada the model analysed annual tidal predictions to convert the weathering data into slope recessional units realistic model profiles with notches at the high tidal level were produced within the 3000 6000 year period since the sea attained its present level there were up to 4 cycles of notch formation and collapse during this time in the rapidly eroding sandstones and a smaller number in the argillites notch morphology was affected by the tidal range the rock type and the initial slope gradient but the maximum depth of the notch before collapse controlled only the number and frequency of the collapse events continuous positive and negative changes in rsl extended the notches in the vertical plane according to the rate and direction upwards or downwards of these changes a distinct series of notches can develop from episodic changes in rsl but the survival of older notches and consequently their utility as palaeosea level indicators depends upon such factors as their elevation with respect to the present tidal range

basin width control of faulting in the naryn basin south central kyrgyzstan 1 in central asia s tien shan deformation is distributed across the wide orogen a characteristic of intracontinental mountain building active faults are commonly found within intramontane basins that separate its constituent ranges in order to explore the controls on this intramontane basin deformation we study the naryn basin of south central kyrgyzstan a series of five balanced cross sections reveals a transition in patterns of faulting from faults confined to basin margins to faults focused within the basin center the 20 km wide eastern naryn basin displays deformation attributed to low angle splays of the northern basin bounding fault in the 40 km wide western naryn basin the pattern of deformation linked to the northern range remains but is accompanied by steeper faults that dip both south and north without being directly linked to the basin bounding fault we compare these cross sections to synthetic aperture radar interferometry insar measurements of surface deformation profiles of insar derived surface deformation rates across the naryn basin reveal that in the west deformation is distributed across the broad basin interior whereas in the east rapid uplift is concentrated at the margin of the narrower basin from the geodetic and structural data we infer that in the western naryn basin deformation has migrated away from the northern basin margin and into the interior deformation of the eastern basin interior however remains linked to the basin bounding fault a simple mechanical model demonstrates that basin width may control basin deformation whereby basin interior faulting in the narrow eastern naryn basin is inhibited by the overburden of adjacent ranges citation goode j k d w burbank and b bookhagen 2011 basin width control of faulting in the naryn basin south central kyrgyzstan tectonics 30 tc6009 doi 10 1029 2011tc002910

deposition models for chronological records abstract long term sedimentary sequences provide a wealth of useful information for research into the palaeo environment especially in relation to past climate change shorter records provide similar information in many archaeological contexts however if such records are to be used to provide precise timing of events and more critically the relative timing between different records methods are needed to provide accurate and precise age depth models for these sequences given the imprecision of individual calibrated radiocarbon determinations it is necessary to use the information we have about the deposition process to refine our chronologies and also to provide interpolation between dated levels in any sequence even with layer counted chronologies the uncertainties are sometimes hard to quantify this paper outlines a range of bayesian models for deposition which have been implemented in the computer programme oxcal these models can be used to combine information from the sediments themselves with radiocarbon or other direct dating information such models have the potential to integrate information between different records and provide a coherent chronology on which to base environmental or archaeological research