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

the influence of parent material on topsoil geochemistry in eastern england the topsoil of around 10 000 km2 in eastern england has recently been sampled intensely at 4609 sites to characterize its geochemistry the parent materials which include both solid geology and quaternary sediments range in age from permian to holocene the distributions of the concentrations of major and trace elements have been characterized geostatistically and the role of parent material on their spatial structure anisotropy and their spatial relationships coregionalization have been investigated analysis of variance with the sites grouped by major parent material type showed that this classi cation accounted for 14 to 48 per cent of the variance for the various elements global variograms of 13 elements al as ca cr cu fe mg mo ni p pb ti and u have been computed and modelled eleven of the variograms seem to comprise two structures both of which we modelled with spherical functions one of short range 3 5 to 9 km and the other with a range of 15 to 23 km the models included a nugget variance which varied from 27 per cent for as fe and mg to 63 per cent for p of the total the long range structures are related to the separations of the major parent materials the variograms of several elements showed appreciable anisotropy most notably that of mg anisotropy is evident at short ranges of less than 5 km this accords with the geological structure of the beds which dip from west to east so that their outcrops are elongated from north to south a linear model of coregionalization tted to the data emphasized several important geochemical associations which we interpret elements commonly associated with clay minerals mg al and the clay size fraction ti are dominated by the long range structure of the coregionalization whilst several trace elements as cr ni and u are spatially correlated with fe over short distances through adsorption of the former on the surfaces of fe oxyhydroxides the topsoil around large urban areas is enriched in lead but it is not clear whether anthropogenic sources are responsible for this metal s anomalous spatial relationships with other elements crown copyright 2003 reproduced with the permission of her majesty s stationery of ce published by john wiley sons ltd

on the interaction of geology measurement and statistical analysis of small scale permeability measurements sedimentary rocks exhibit small scale mm permeability variations which can be detected with a probe permeameter the structure of the laminations may provide evidence about the characteristics of the measurement device the statistical interpretation of these measurements using averages and variograms is enhanced when the geological character of the rock is taken into consideration the three aspects of rock characterization namely geology measurement and statistical analysis are best assessed in concert this theme is illustrated using probe data taken from sections of the rannoch and etive formations northern north sea

salt weathering simulations under hot desert conditions agents of enlightenment or perpetuators of preconceptions because of access difficulties and inhospitable environmental conditions our understanding of rock weathering in hot deserts has been strongly influenced by laboratory simulations however a risk exists that results may come to owe more to experimental design than to actual environmental conditions experienced at the atmosphere rock surface interface this was especially true in early salt weathering simulations that seemingly sought to reinforce the orthodoxy of a physically dominated weathering environment driven by extremely high absolute temperatures and large diurnal temperature ranges however improvements in environmental sensors over the last 20 years have established the complexity of desert climates and the importance of microclimatic controls and allowed considerable refinement of experimental design this overview evaluates the implications of recent simulation studies and presents new information on possible fatigue effects of differential thermal expansion of salts and the salt weathering of test blocks under compressive loading in doing so it demonstrates how physical rock properties change during experimentation the importance of short term surface temperature fluctuations distinctions between the weathering of unconfined debris and larger rock surfaces the importance of moisture and salt applications that replicate their availability in deserts the importance of rock thermal properties in controlling their weathering response in environments dominated by radiative heating and cooling and the overall complexity of weathering regimes

comparative investigation of the spatial distribution of past weathering impacts on sandstone masonry abstract inspection of the deterioration of both natural outcrops and historical built stone facades reveals that patterns of disruption are not uniform indicating the influence of material and environmental properties sandstones have a spatial variability in weathering response for this reason geostatistical techniques have been applied to studies of sandstone properties mineralogical and structural that influence susceptibility to decay for this study a comparative analysis of permeability data acquired from a quarry fresh stone and a weathered sample is undertaken the depositional processes that resulted in the formation of sandstone also create structures of spatial variation such as laminations or larger bedding planes within the material using geostatistical techniques the permeability variance observed within quarry fresh blocks of sandstone indicates the subsampling of larger geological structures when cut from the quarry face once blocks have been emplaced within a building they will be subjected to the increased stress of the urban environment these conditions result in exacerbated weathering through processes such as salt and chemical weathering weathering can alter material properties such as permeability with the creation of a secondary permeability produced by the opening pores and alteration of pore connectivity through the application of geostatistics in the analysis of permeability data observed from the weathered block variography reveals the presence of smaller scale structures this suggests that alteration of the sandstone s permeability has led to the creation of new weathering structures within the stone overwriting the initial sedimentary structures these weathering related structures will affect both the magnitude and spatial distribution of permeability within the weathered block the interconnected pathways of permeability created by past weathering facilitate the migration of moisture and salts in solution through the substrate this work has demonstrated that through a geostatistical approach with the application of co kriging these potential moisture pathways can be identified and visualised

does a monsoon climate exist over south america the climatology and the basic state of the summertime circulation and rainfall over south america are studied using assimilation products from the data assimilation system of goddard earth observing system 1 geos1 and satellite derived rainfall results indicate the existence of a regional summer monsoon circulation regime induced by strong diabatic heating over the subtropical south american highland centered at the altiplano plateau sensitivity of the results to the assimilation scheme is tested by comparing that with the national centers for environmental prediction ncep reanalysis and with satellite rainfall estimates results show general agreement between the model produced rainfall anomaly and the satellite estimates as well as consistency between the basic circulation features in the geos 1 and the ncep reanalyses a case study of 1989 90 south american summer monsoon sasm reveals the following characteristics 1 in late spring the onset of sasm is signaled by an abrupt merging of the upper tropospheric double westerly jets one in the subtropics and the other in the subpolar region into a single jet in the midlatitudes this is followed by the establishment of a vortex to the southeast of altiplano and occurrence of heavy precipitation over subtropical eastern brazil 2 during the mature phase of sasm the heavy rainfall zone moves over the altiplano plateau and the southernmost brazilian highland the fully established sasm features are the following a an enhancement of equatorial north atlantic trade wind which emanates from the sahara high and crosses the equator over the south american continent b a buildup of strong northwesterlies along the eastern side of the tropical andes and c development of the south atlantic convergence zone in the southernmost position with strong convective activity meanwhile the upper tropospheric return flow emerges from an anticyclone formed over the altiplano plateau crosses the equator and sinks over northwestern africa 3 the withdrawal of sasm in late summer is signaled by the resplitting of the midlatitude westerly jet at the same time the low level northwest monsoon flow diminishes reducing the moisture supply and leading to the termination of heavy precipitation over the subtropical highland results also show that the above mentioned characteristics of sasm are clearly linked to the tropospheric temperature changes over the central south american highland sensible versus latent heating over the highland are bound to play an important role in the evolution of sasm to provide further support of presence of a monsoon climate over south america sasm is compared and contrasted to the classic east asian summer monsoon easm many similar features including evolution characteristics between the two systems have been identified contrasting aspects of the sasm from the easm are also discussed it is pointed out that a number of monsoonal characteristics of the climate of south america such as the seasonal reversal of the low level wind become apparent only when the strong annual mean wind is removed based on the characteristic features and their evolution the authors conclude that a monsoon climate does exist over south america

characterization of the paleocrusts of weathered carboniferous volcanics from the junggar basin western china significance as gas reservoirs abstract volcanic reservoirs comprise reservoir spaces made up of pores and cracks with secondary solution pores and tectonic induced cracks being the most dominant various volcanic lithologies and lithofacies show differences in porosity and permeability because resistance to weathering differs among volcanic rock types this study shows that among volcaniclastic rocks volcanic breccia shows higher porosity and permeability as well as poor pore radius sorting and connectivity compared with volcanic tuff basalt and monzonitic porphyry show higher porosity and permeability compared with other volcanic lava and subvolcanic rocks the level of porosity of different facies is in the order of effusive facies explosive facies subvolcanic rock facies volcanic sedimentary facies eruptive facies reservoirs show relatively high porosity and permeability near the top surface of the weathered crust porosity and permeability generally decrease with an increase in the distance from the carboniferous top weathered crust this condition indicates that weathering controls the properties of volcanic reservoirs the distribution pattern of porosity and permeability in the weathered crust of volcanic facies differs strong weathering contributes to a decrease in porosity and permeability at the top part of the weathered crust various weathering effects on volcanic rocks control porosity and permeability vertically and the gas accumulates mainly in the range of 0 m 200 m from the top of the weathered crust gas accumulation in subvolcanic and volcaniclastic rocks is better than that in volcanic lava the log curve in geophysical exploration can help determine the vertical structure of weathered crust the strong weathering belt shows high gamma low electrical resistivity low density high neutron porosity and high interval transit time

gypsum formation in non calcareous building sandstone a case study of scrabo sandstone this paper addresses one central issue of building stone research an origin for calcium in gypsum formation in non calcareous sandstones a comparative study of scrabo sandstone from outcrops and a 120 year old building in central belfast shows how weathering has significantly altered the mineralogy preliminary results suggest that the occurrence of gypsum throughout the stone blocks is related to chemical reactions between a pore filling mineral constituent actinolite ca mg amphibole and sulphur oxides from urban pollution these findings advocate an internal source of calcium for gypsum formation and provide new evidence to explain the enhanced decay displayed in some scrabo sandstone copyright 2001 john wiley sons ltd

resonant near surface inertial oscillations in the northeastern gulf of mexico the inertial frequency is nearly diurnal at 30 n latitude which transects the northeastern gulf of mexico negom at this latitude near surface inertial oscillations can amplify due to resonance with diurnal wind forcing diurnal oscillations have also been attributed to diurnal tidal forcing in this region because tidal forcing wind forcing and inertial oscillations are nearly diurnal a unique series of comparative analyses are required to determine their relative influence on surface circulation by comparing surface currents obtained by hf radar to predictions of the inertial response to wind forcing and barotropic tidal currents it is found that diurnal oscillations in the negom were predominantly due to wind forced inertial oscillations in june 2010 the analyses provide a unique spatiotemporal perspective of inertial oscillations in the negom where there is evidence of propagation frequency and phase shifts and amplitude variability because inertial oscillations mix the ocean differently than the tides these results provide insight into how inertial oscillations potentially mixed oil from the deepwater horizon spill in june 2010 near diurnal oscillations during the winter were found to be predominantly due to tidal forcing when wind driven inertial oscillations were diminished due to a presumably deeper mixed layer

dynamical instability in surface permeability characteristics of building sandstones in response to salt accumulation over time abstract this paper explores how the surface permeability of sandstone blocks changes over time in response to repeated salt weathering cycles surface permeability controls the amount of moisture and dissolved salt that can penetrate in and facilitate decay connected pores permit the movement of moisture and hence soluble salts into the stone interior and where areas are more or less permeable soluble salts may migrate along preferred pathways at differential rates previous research has shown that salts can accumulate in the near surface zone and lead to partial pore blocking which influences subsequent moisture ingress and causes rapid salt accumulation in the near surface zone two parallel salt weathering simulations were carried out on blocks of peakmoor sandstone of different volumes blocks were removed from simulations after 2 5 10 20 and 60 cycles permeability measurements were taken for these blocks at a resolution of 20 mm providing a grid of 100 permeability values for each surface the geostatistical technique of ordinary kriging was applied to the data to produce a smoothed interpolation of permeability for these surfaces and hence improve understanding of the evolution of permeability over time in response to repeated salt weathering cycles results illustrate the different responses of the sandstone blocks of different volumes to repeated salt weathering cycles in both cases after an initial subtle decline in the permeability reflecting pore blocking the permeability starts to increase reflected in a rise in mean maximum and minimum values however between 10 and 20 cycles there is a jump in the mean and range permeability of the group a block surfaces coinciding with the onset of meaningful debris release after 60 cycles the range of permeability in the group a block surface had increased markedly suggesting the development of a secondary permeability the concept of dynamic instability and divergent behaviour is applied at the scale of a single block surface with initial small scale differences across a surface having larger scale consequences as weathering progresses after cycle 10 group b blocks show a much smaller increase in mean permeability and the range stays relatively steady this may be explained by the capillary conditions set up by the smaller volume of the stone allowing salts to migrate to the back of the blocks and effectively relieving stress at the front face

patterns of movement in rotational and translational landslides the movement of rotational and translational landslides occurs as a result of either sliding on discrete shear surfaces or ductile deformation within a shear zone in this paper we examine the movement histories of a number of landslides that occurred in a variety of materials in a range of settings and demonstrate that one of two movement styles is evident during accelerating phases for all landslides observed the first style which has previously been noted has a linear form in a plot of 1 v against time v is velocity the second style has an asymptotic form in the same plot trending toward steady state movement rates we propose that the linear form occurs in landslides in which crack propagation i e shear surface generation is the dominant process whereas the second style occurs where movement is taking place across existing planes of weakness or as a result of ductile deformation processes this study demonstrates that the evaluation of plots of 1 v against time for landslides is a useful technique for forecasting movement styles and rates and for interpreting ongoing deformation processes in real time

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

geostatistical analysis in weathering studies case study for stanton moor building sandstone geostatistical techniques for spatial prediction and spatial simulation have been used in an innovative application to the study of weathering of natural building stone the study investigates the differences in the spatial variation of permeability characteristics between fine and coarse grained stanton moor building sandstone non destructive permeability measurements using an unsteady state portable probe permeameter were made on three adjacent faces of two cubic blocks representative of fine to medium grained and medium to coarse grained stanton moor sandstone the findings provide greater understanding in the investigation of the durability characteristics of the stanton moor sandstone and show that the spatial distribution and variability of permeability is more important in predicting the overall strength and weathering properties than mean permeability and absolute minimum and maximum values the results suggest that both primary textural characteristics such as grain size and extent of cementation appear to be important factors in determining the overall durability properties of stanton moor sandstone as a building stone geostatistical analysis has been shown to be an important tool in the characterization of spatial variation for the investigation of weathering of building stones copyright 2006 john wiley sons ltd

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

probe permeametry is it worth the effort abstract an overview is given of the wide variety of current applications for probe permeameter technology and data in light of recent key advances in reservoir characterization the future trends in applications and tool development are discussed by examining the procedures and costs associated with data acquisition quality control and general information enhancement and by comparing these factors to more conventional methods for obtaining permeability it is concluded that probe permeametry is indeed worth the effort

variable weathering response in sandstone factors controlling decay sequences differences in weathering response characteristics of fine and coarse grained stanton moor sandstone samples were assessed in a laboratory weathering simulation experiment using a variable combination of salt weathering and freeze thaw cycles preliminary analysis of permeability characteristics identified similar mean values for each type of stanton sandstone but significant differences in the range of values between the two sample sets with coarse grained samples of stanton moor sandstone displaying a restricted range of values in comparison to fine grained samples which showed much greater within block variation data indicated that the greater the range in initial permeability values the greater the potential for salt and moisture ingress and retention and hence eventual disruption of the fabric of the stone experimental data also identified different stages in decay sequences with significant structural change occurring during the initial preparatory stage before material breakdown and loss became apparent evidence suggests that relatively minor structural and mineralogical differences between samples of the same stone type can have a significant influence on weathering behaviour resulting in distinct rates and patterns of breakdown copyright 2005 john wiley sons ltd