radiocarbon dates on deglaciation cordillera central northern peruvian andes abstract three radiocarbon dates along with relative dating criteria place limits on the deglaciation history of manachaque valley cordillera central ice retreated from the late glacial maximum by at least 12 100 yr b p during ice retreat numerous moraines were deposited throughout the valley glacier cover was reduced to about half that of the last glacial maximum by at least 9700 yr b p and to less than a tenth by at least 6450 yr b p because all dates are minimum the dates and field data are consistent with little or no ice remaining by early holocene no unambiguous younger dryas moraines are present

thermal decay of carbonate dimension stones fabric physical and mechanical changes this paper deals with the effects of thermal stresses on selected carbonate rocks used as dimension stones they are mesozoic calcareous and dolomitic rocks cropping out in apulia southern italy that for their physico mechanical and aesthetic properties have always been finding a large application both as ornamental stones and as simple construction materials their use is attested not only in italy in works of archaeological historical and artistic interest too the cause effect relationships of thermal degradation were studied by means of an artificial accelerated ageing test in order to provide a perspective about the decay of carbonate stones due to diurnal and seasonal temperature fluctuations as well as thermal shocks during events of fire development the stone samples were subjected to thermal cycles in a muffle furnace ranging from 100 to 700 c after each cycle several non destructive and semi destructive tests were carried out mass and volume measurements mercury intrusion porosimetry sclerometer tests ultrasonic tests thin section observations and determination of chromatic alterations through image analysis and munsell charts method in this way the qualitative and quantitative modifications induced in fabric physical and mechanical properties were discussed the results highlight the fundamental role of depositional and diagenetic fabric that together with mineralogical composition represents the most significant discriminating factor in the response of the stone to thermal stresses

the effect of rock strength on weathering rates of sandstone used for angkor temples in cambodia abstract this study determined the weathering rates from the depths of hollows formed by the deterioration of sandstone blocks used to build angkor temples in the 7th 12th centuries due to capillary processes these hollows generally develop at the bases of building components such as doorframes false doorframes window frames and pillars in this study 55 locations in 29 temples were selected to measure maximum hollow depth based on the ages of the temples the weathering rate was calculated to be in the range 7 92 mm ka 1 the weathering rate was found to be independent of building component type and aspect the calculated weathering rate corresponds to the physical weathering rate of sandstone caused by the wetting drying cycles that result from the tropical environment along with the dry season an equation that can estimate the maximum depth of a hollow in a sandstone block was proposed based on temple age and the coefficient obtained from two types of rock hardness values the equation coefficient is an effective index that can help predict the deterioration of stone cultural artifacts such as the angkor temples

engineering geological and geoenvironmental evaluation of unesco world heritage site of meymand rock hewn village iran meymand a historic 2000 year old village is an important heritage site in iran that was included on the world heritage list in 2015 by unesco the village is located in a volcanic terrain and its structures such as houses a mosque a public bath and a fire temple have been carved in to the pyroclastic rocks of the masahim volcano in the present study the engineering geological and geoenvironmental aspects of the meymand village were investigated including the geomorphology and landscape of the village the technical classification of the pyroclastic rocks and their geomechanical properties and the geoenvironmental characteristics and problems of the village the engineering geological characteristics of the meymand site were also compared with those of similar sites of the cappadocia region in turkey and the kandovan village in iran which were widely studied by earlier researchers the results of the present study indicated that the erosion of massive volcanic rocks free from systematic structural discontinuity has formed the unique landscape of the village which is different from similar other sites according to technical classification the meymand pyroclastic rock is a lithic tuff of a low degree of welding that has very weak strength and low durability accelerated weathering tests that artificially simulated the meymand site conditions suggested that the meymand tuff is prone to atmospheric conditions as its strength and deformability are drastically reduced when it becomes wet or saturated laboratory tests and field evidence show that the meymand village is under threat of erosion due to natural and anthropogenic agents that gradually destroy the landscape and structures of this significant world heritage site therefore conservation projects should be planned and applied that ensure the preservation of the village

delta progradation and neoglaciation laguna paron cordillera blanca peru the history of holocene glaciation serves as an important record of glacier mass balance and therefore of climatic change the moraine record of holocene glaciation in the tropical andes however is fragmentary and poorly dated in contrast increases in the rate of accumulation of inorganic sediment in glacier fed lakes have been linked to periods of neoglaciation in many mountain regions the interpretation of such a record of neoglaciation from sediment cores in glacier fed lakes in the tropical andes can provide the continuity and chronologic control that is lacking in the existing moraine record unusual exposures of glacial lacustrine sediment in the cordillera blanca peru provide a rare opportunity to assess the link between climatic change glaciation and lacustrine sedimentation intentional lowering of water levels in laguna paron 9 s 77 44 w 4200 m a s l in 1985 resulted in the incision and exposure of at least 20 m of deltaic deposits at the eastern end of the lake three deltaic units can be identified horizontal topset beds steeply dipping and deformed foreset beds and horizontally laminated fine grained sediment six radiocarbon ages ranging from 1800 210 to 465 95 14c yr bp on wood indicate that the average rate of delta progradation in the late holocene has been approximately 290 m per 1000 yr the lake formed during deglaciation at least 10 000 yr ago and if such a rate of progradation of the delta had prevailed over the entire holocene then the delta would be at least three times as extensive as it is today thus the rate of delta progradation has varied significantly over the holocene we suggest that the rate of delta progradation was at least three times greater when glaciers were in advanced positions these positions are clearly delimited by neoglacial moraines which are within 1 2 km of the exposures studied and within 1 km of modern ice limits the most recent increase in the rate of delta progradation is evidenced by an increase in sedimentation rate ca 575 90 14c yr bp coincident with the onset of the little ice age copyright 2005 john wiley sons ltd

sedimentological characteristics of the surficial sediments of the kuwaiti marine environment northern arabian gulf the textural characteristics carbonate content and the coarse fraction components of the recent bottom sediments of the marine environment off kuwait are described and the faunal sediment associations discussed the sediments were subdivided into seven textural classes namely sand silty sand muddy sand sandy silt sandy mud silt and mud most of the study area is covered with muddy sediments whereas sandy deposits are restricted to the rocky bottoms near the southern flat of kuwait bay the southern coast of kuwait and around the islands and bathymetric highs the textural classes carbonate contents and faunal types of the coarse fraction were used to construct a biolithofacies map of the marine bottom sediments off kuwait in which nine facies are identified the sedimentological characteristics of the recent marine bottom sediments off kuwait reflect the interaction between autochthonous calcareous fragments mostly of biogenic origin lime rock fragments derived from beachrocks and submerged reef flats and allochthonous terrigenous detritus transported to the area mainly by dust storms the kuwaiti offshore area is generally a low energy depositional environment with little sediment transport

direct observation of microcrack development in marble caused by thermal weathering one of the properties that makes marble such an excellent construction and ornamental material is its low porosity it is very difficult for water or decay agents to penetrate the internal structure of materials with no or few pores so enhancing the durability of these materials however environmental temperature fluctuations bring about significant physical changes in marbles that result in an increase in porosity due to the appearance of new microcracks and the expansion of existing ones these cracks offer new paths into the marble which make it easier for solutions containing pollutants to penetrate the material thermal expansion tests were performed on three different types of marble known as white tranco and yellow macael almeria spain after which an increase in porosity from 17 to 73 depending on marble type was observed mainly due to crack formation the structural changes occurring during thermal expansion tests were more significant in the case of white macael samples a fact that is not only related to its mineralogical composition but also to the morphology of the grains grain boundaries and crystal size our research suggests that thermally weathered white macael marble could be more susceptible to decay by other contaminant agents than tranco or yellow macael the use of hot stage environmental scanning electron microscopy is proposed as a valid tool for observing both in situ and at high magnification changes in the fracture system of building stones induced by thermal stress

soil catena variation along an alpine climatic transect northern peruvian andes abstract morphological and chemical properties of soils developed on end moraines of mostly quartzitic and granitic composition in the puna region of the northern peruvian andes vary with slope position and climate soil development was assessed on two catenas of similar age range 8 12 ka in two different precipitation zones at summit backslope and footslope positions soil properties that show trends downslope and with increased rainfall are greater clay content greater organic carbon content and greater pedogenic fe content in addition ph is lower in the higher rainfall area eolian material mixed loess forms the surface layer a horizon and may be responsible for the remarkable slope stability in the area it is suggested that mixed loess provided material for chemical alteration and translocation of clay and fe vertically and downslope in quartz rich parent materials soil data suggest that the amount of climate change during the holocene is limited it is doubtful if the climate at the wetter end of the transect ever existed at the drier end

evidence for holocene stability of steep slopes northern peruvian andes based on soils and radiocarbon dates summary radiocarbon dating and soil relationships indicate that landscapes in highaltitude glaciated valleys of the northern peruvian andes have been remarkably stable during the holocene radiocarbon dates show that deglaciation was underway by 12 ka and that slopes and alluvial fans at the bases of slopes were essentially stabilized by at least 8 ka the soils consist of fine grained loessial a horizons overlying bw horizons in gravelly till or alluvial fan gravel following deglaciation widespread gullying took place in till on the steep maximum angle 37 sideslopes of most valleys the eroded material was deposited as fans at the bases of the slopes loess was then deposited as a fairly uniform blanket across most elements of the landscape soil formation began during or following loess deposition and because soil profile morphology is sufficiently similar at most sites soil formation has been a dominant process during much of the holocene this remarkable stability especially for such steep slopes is attributed to a combination of tight packing of the till permeability of the capping loess rapid revegetation following ice retreat and roots from the present grassland vegetation and possibly former forests

subdivision of late pleistocene moraines in the cordillera blanca peru based on rock weathering features soils and radiocarbon dates abstract the progressive development of unusual rock weathering features and soils and minimum limiting radiocarbon dates provide a basis for subdividing four groups of late pleistocene moraines on the west side of the cordillera blanca northern peru 9 20 1 000 s 77 10 77 30 w boulders on the youngest late pleistocene moraines have 10 to 14 cm tall weathering posts soils on these moraines yield mean profile development index pdi values of 0 05 0 04 1 these moraines date between ca 13 500 and 9700 500 yr b p older than previously postulated the next older moraines have boulders with weathering post heights between 20 and 25 cm and soils with pdi values of 0 08 0 07 and were deposited prior to 13 280 190 yr b p probably during the last glacial maximum marine isotope stage 2 moraines from an older glaciation have boulders with weathering posts between 39 and 50 cm high soils that yield pdi values of 0 21 0 07 and are older than 19 700 340 yr b p boulders on moraines from a still older glaciation have lost ca 50 of their above ground volume and have weathering posts between 62 and 70 cm high pdi values for soils on these moraines are 0 32 0 06 linear and logarithmic models of weathering post and soil development with time are used to estimate minimum and maximum ages for the two oldest moraine groups linear models suggest that the second oldest moraines are between ca 20 500 and 46 500 yr b p and that the oldest moraines are between ca 29 000 and 72 000 yr b p in contrast logarithmic models suggest ages of greater than ca 75 500 yr b p and greater than ca 500 000 yr b p respectively

holocene provenance shift of suspended particulate matter in the amazon river basin abstract the strontium sr neodymium nd and lead pb isotope signatures of suspended particulate matter spm in rivers reflect the radiogenic isotope signatures of the rivers drainage basin these signatures are not significantly affected by weathering transport or depositional cycles but document the sedimentary contributions of the respective sources we report new sr nd and pb isotope ratios and element concentrations of modern spm from the brazilian amazon river basin and document the past evolution of the basin by analyzing radiogenic isotopes of a marine sediment core from the slope off french guiana archiving the last 40 kyr of amazon river spm and the holocene section of sediment cores raised between the amazon river mouth and the slope off french guiana the composition of modern spm confirms two main source areas the andes and the cratonic shield in the marine sediment core notable changes occurred during the second phase of heinrich stadial 1 i e increased proportion of shield rivers spm and during the last deglaciation i e increased proportion of madeira river spm together with elsewhere constant source contributions furthermore we report a prominent offset in sr and nd isotopic composition between the average core value end 11 7 0 9 2sd 87sr 86sr 0 7229 0 0016 2sd and the average modern amazon river spm signal end 10 5 0 5 2sd 87sr 86sr 0 7213 0 0036 2sd we suggest that a permanent change in the amazon river basin sediment supply during the late holocene to a more andean dominated spm was responsible for the offset

a quantitative analysis of recent arid coastal sedimentary facies from the arabian gulf coastline of abu dhabi united arab emirates abstract this study presents the results of the first quantitative analysis of surface sediments along multiple transects of the arabian gulf shoreline of abu dhabi united arab emirates the natural coastline of this low angle carbonate ramp depositional system is being anthropogenically modified at an unprecedented rate as this system is much employed as a recent analogue for many ancient depositional sequences it is imperative that sedimentological characteristics of natural facies occurrences are accurately recorded for employment in future applications we establish distinct relationships between the geomorphic setting and sediment characteristics siliciclastic grains admixed to this system are naturally sourced from the pliocene ghayathi formation and from aeolian sediment influx during dust storms this natural source of siliciclastic detritus is being increasingly superseded by siliciclastic material derived from anthropogenic activities evaporite minerals are similarly being contributed from anthropogenic sources the occurrence of mud to silt grade sediments is primarily controlled by the presence of a sediment binding microbial mat that prevents the removal of fine material during high energy events similarly the presence of a halite crust in the upper tidal flats and supratidal zone prevents aeolian deflation this study did not establish any clear relationship between coastal geomorphic setting and the bioclastic components present in the sediments this finding has major implications for the application of bioclasts in fine tuning palaeoenvironmental interpretation of ancient carbonate ramp coastal systems

comments on c m clapperton s glacier readvances in the andes at 12500 10000 yr bp implications for mechanism of late glacial climatic change

influence of mineralogy on granite decay induced by temperature increase experimental observations and stress simulation abstract rocks can be subjected to high temperatures in several instances as for example in geothermal processes or if affected by fires temperature variations lead to a complex stress distribution in crystalline rocks due to mineral thermal expansion in polymineralic such as granites these stresses depend on fabric parameters such as mineral proportion grain size and their related thermal properties eight granitic rocks were heated to less than 400 c and their decay patterns were observed and quantified by means of scanning electron microscopy heating was also modeled by finite element simulations oof software with polymineralic microstructures quartz feldspar and biotite contents were used as a variable in the model in order to elucidate the influence of mineralogy on the thermal elastic response of granites real and modeled heating showed similar trends of microcracking in microstructures and of thermal expansion coefficients microscopic observations of real samples revealed mainly intragranular microcracks in quartz opening of cleavage plains and deformation in mica simulations confirmed that in spite of the high thermal and anisotropic expansion of quartz the microstructure of rocks with large amounts of quartz does not necessarily experience large stresses biotite produces a concentration of stresses along their grain boundaries as a result oof models with 10 biotite showed higher stresses than monomineral ones thermal expansion coefficients of real granites fitted within the limits of the simulated ones proving once more the success of using finite element modeling applied to polymineralic rocks

climate in the western cordillera of the central andes over the last 4300 years abstract the distichia peat core obtained in the carhuasanta valley near nevado mismi cordillera chila provides information on climatic and environmental conditions over the last 4300 years the relative changes in the stable carbon isotope composition of plant remains preserved in the core reflect major temperature fluctuations in the western cordillera of the southern peruvian andes these temperature variations can be additionally linked with the changes in precipitation patterns by analysing c and c n ratio in the core relatively warm and moist conditions prevailed from 4280 to 3040 cal yrs bp bc 2330 1090 with a short colder dry episode around 3850 cal yrs bp bc 1900 the most prominent climate changes recorded in the peat occurred between 3040 and 2750 cal yrs bp bc 1090 800 when the initial warming turned to a rapid cooling to temperatures at least 2 c lower than the mean for the late holocene initially drier conditions within this event turned to a short wet phase after 2780 cal yrs bp bc 830 when the temperature increased again this event coincides with significant changes in peat and ice core records in the central andes matching the timing of the global climate event around 2 8 cal ka bp climatic conditions in the study area became relatively dry and stable after the event for about 800 years highly variable temperatures and humidity prevailed during the last 2000 years when an extended warm and relatively humid period occurred between 640 and 155 cal yrs bp ad 1310 1795 followed by predominantly colder and drier conditions the established 13 c peat record represents the first continuous proxy for the temperature in the southern peruvian andes dated by the ams 14 c distichia peat is wide spread in the andes and the proposed approach can be applied elsewhere in high altitudes where no other traditional climate proxies are available

pleistocene glaciation in the southern lake district of chile relative age criteria permit deposits of successive andean glacier advances in the southern lake district of chile to be divided into four mappable drift sheets the oldest two of which overlie tertiary bedrock along the eastern flank of the cordillera de la costa only the youngest drift llanquihue is datable by radiocarbon during the most extensive ice advance of the last glaciation the lago llanquihue glacier was about 95 km long and reached an estimated maximum thickness of between 1000 and 1300 m glacier equilibrium lines at that time lay about 1000 m below their present level and rose eastward with a gradient of about 5 m km successive ice advances in the lago llanquihue basin which resulted in construction of end moraines and associated outwash plains beyond the lake margin culminated sometime before about 20 000 yr ago and between 20 000 and 19 000 yr ago a later readvance inferred from the sedimentary record of lake level fluctuations in the basin had begun by about 15 000 yr ago and culminated shortly after 13 000 yr ago a comparable but less closely dated record of ice advances is found northwest of seno reloncavi and on isla chiloe deglaciation following the latest advance is likely to have been rapid for the major glacier lobes fronted on deep water bodies that would have promoted extensive calving

a reevaluation of the evidence for a younger dryas climatic reversal in the tropical andes abstract a review of the evidence for a younger dryas equivalent climatic reversal in the tropical andes shows that a number of hypotheses need to be reassessed assumptions of the el abra cold and humid phase in colombia are compromised by insufficient dating control periods of glacier advance in peru and bolivia lack sufficient dating control to be correlated with the european younger dryas only glaciers on the quelccaya ice cap in peru may have advanced shortly before the onset of the european climatic reversal but even there a correlation is questionable a late glacial advance in the chimborazo area in ecuador is considerably older than previously suggested the same glacier advance has been dated to earlier than 12 000 bp in other areas of ecuador the emerging picture suggests two phases of glacier advances in the tropical andes 13 000 12 000 bp and 9000 10 000 bp both may have been caused by increasing precipitation unequivocal evidence for a cold younger dryas event in the tropical andes has yet to emerge

the pleistocene holocene transition in peru and its effects upon human use of the landscape abstract this paper reviews the state of our knowledge regarding the effects of the pleistocene holocene transition on the kinds and range of human adaptations in what is now peru following a discussion of geological paleoclimatic and archaeological data the paper focuses upon four aspects of environmental change with specific regard to how these would have affected human adaptations environmental changes on the pacific littoral the extinction of pleistocene faunal and floral species and their replacement with modern faunas the adaptive radiation of these modern flora and fauna especially into the andean highlands and characteristics of newly available high elevation environments that would have affected the process by which foraging peoples moved into them although pleistocene fauna have been discovered in peru none of these finds have been made in the context of indisputable human activity and therefore the effect of their extinction on early foraging peoples is unknown the earliest acceptable archaeological sites in peru date around 11 12 000 years ago and are found on the coastal lowlands the highlands were not occupied until after 11 000 years ago while high elevation environments were attractive after 11 000 years ago they were only slowly occupied by humans due to the constraints of the combined effects of hypoxia and cold

effect of mixed vs single brine composition on salt weathering in porous carbonate building stones for different environmental conditions abstract the influence of different factors brine composition environmental conditions and pore structure on salt weathering of porous carbonate building stones is investigated the main goal of this study is to highlight the differences in weathering between single salts and a mixture of different salts two kinds of weathering mechanism are studied the crystallization pressure and the deliquescence recrystallization process to achieve this purpose wetting and drying cycles and cycles varying relative humidity on samples containing salts were performed the effect of total salt content with different salts and mixtures is simulated by weathering tests with solution of different compositions nacl 6 in weight na 2 so 4 10h 2 o 6 in weight caso 4 at saturation and a mixture of them at total concentration of 6 2 weathering tests were performed at room temperature and 50 c and under low and high relative humidity the results show that the final weathering depends on a complex combination of three parameters i environmental conditions ii salt composition and iii petrophysical properties of stones and general conclusions on the impact of each parameter can be drawn an important result is that salt mixtures have a lesser impact on weathering during crystallization cycles single salt brines especially sodium sulphate produce more weathering than complex brine compositions during wetting and drying cycles conversely during variations on rh samples with salt mixtures suffer more damage than samples weathered with a brine of single salt composition

durability of carbonate rock as building stone with comments on its preservation carbonate rocks have been extensively used as building stones because of their availability workability and attractiveness unfortunately however some stones suffer from chemical attack or freeze thaw activity the environmental affects especially those due to pollution of the atmosphere are discussed in terms of weathering processes salt crystallization and acid deposition a review of some recent research in relation to deterioration of stone in urban environments is given and carbonate rocks are classified in relation to position within a building geographical location and degree of pollution some comments on stone preservation are provided especially in terms of the properties a preservative should possess

formation of diagenetic dolomite in coastal sabkha along arabian persian gulf aragonitic intertidal sediments are being dolomitized in the subsurface supratidal environment of a sabkha along the south shore of the arabian persian gulf as a result of the percolation of wind driven marine derived brines the development of abundant diagenetic dolomite results from an optimum combination of high mmg mca ratio fluids a rapid flow rate which is related to the flooding frequency and sediment permeability and a shoreline configuration that maintains the proper conditions for a sufficient length of time strongly dolomitized areas are localized along the flanks of remnant channels and in the lee of islands that have been engulfed by the prograding sabkha the dolomitizing process takes about 1 000 to 1 500 years most diagenetic dolomite forms at the expense of primary aragonite according to the reaction mg 2caco3 arag rarr camg co3 2 ca dolomite forms under the following conditions a chloride concentration between 3 25 and 3 75 mcl kg b mmg mca greater than about 6 c ph between 6 3 and 6 9 d minimum pco2 of 10 2 to 10 3 atm e temperature between 25 and 40 c f saturation with respect to gypsum and g reducing environment in association with hydrogen sulfide other recent dolomite occurrences in the bahamas florida and bonaire are significantly different in terms of stratigraphy degree of lithification and evaporite mineral association from those in the arabian gulf

physical weathering of building stones induced by freeze thaw action a laboratory long term study damages to natural building stones induced by the action of frost are considered to be of great importance commonly the frost resistance of building stones is checked by standardised freeze thaw tests before using corresponding tests normally involve 30 50 freeze thaw action cycles in order to verify the significance of such measurements we performed long term tests on four selected rocks over 1 400 freeze thaw action cycles additionally numerous petrophysical parameters were analysed to compare the behaviour of rocks in the weathering tests according to the current explanatory models of stress formation by growing ice crystals in the pore space the long term tests yield more information about the real frost sensibility of the rocks a clear deterioration cannot be determined in most cases until 50 weathering cycles have been completed in the freeze thaw tests the samples are also stressed by changing temperature and moisture indicating that different decay mechanisms can interfere with each other thus thermohygric and moisture expansion are important damage processes

potential glacial evidence for the younger dryas event in the cordillera of north and south america there is debate as to whether or not the younger dryas yd climatic event affected areas outside of the north atlantic region the potential of alpine glacial deposits to record the yd is of interest because alpine glaciers would be likely to leave a morainal record even during minor short lived advances caused by a period of deteriorating climate in the cordilleran ranges of north and south america there are several candidate moraines many bracketed between radiocarbon ages of ca 12 and 10 ka which may be yd in age the best examples are in the canadian and american rockies the ecuadorian peruvian and bolivian andes and around the patagonian ice cap in most cases temporal brackets are not narrow enough and some radiocarbon ages may not be accurate enough to allow correlation at the present time there are two cases of lateglacial readvance whose ages are interpreted to match or fall within the yd interval an advance of the crowfoot glacier in canada is interpreted to have occurred within the period ca 11 3 and 10 14c ka bp and an advance of the reschreiter glacier in ecuador is interpreted to have culminated in the period ca 11 to 10 6 14c ka bp the latter interpretation depends on an assumption that lake level variations were caused by glacier advances and retreats

palynology of cushion bogs of the cordillera pelada province of valdivia chile abstract fossil pollen identified in the earliest sediments of three cushion bogs in the cordillera pelada 40 10 s 73 30 w dated 10 425 14 c yr b p includes the subantarctic species dacrydium fonckii tetroncium magellanicum astelia pumila gaimardia australis donatia fascicularis and drosera uniflora all grow today in the cordillera pelada and range poleward to the southernmost province of magallanes one species drapetes muscosa included with the pollen of these plants in the earliest record is no longer a constituent of the flora but is limited only to subantarctic chile available evidence indicates that plants survived the last glaciation north of the glacial border with the course of postglacial migration southward following the wastage of the glacier complex holocene climatic and vegetational changes in the cordillera pelada are interpreted in the context of regional reconstructions which show maximum warmth about 9000 yr ago with a pronounced dry period lasting from 9000 to 6500 yr b p maximum precipitation was later reached around 4000 yr ago but has decreased overall since then the regional decline of the endemic gymnosperm fitzroya cupressoides which today is extensively destroyed in the cordillera pelada follows this decrease in precipitation these climatic data suggest a net south ward shift in the zone of westerly winds that bring rainfall to the region over the past 4000 yr

spatial attenuation the most sensitive ultrasonic parameter for detecting petrographic features and decay processes in carbonate rocks abstract the evaluation of stone quality by means of non destructive tests is of vital importance especially when rock is used as a building material usually however only vp p wave velocity is considered when rock properties such as strength durability or decay level are assessed in this paper we propose a novel ultrasonic estimator based on wave energy spatial attenuation s the benefits of this estimator were evaluated by comparison with five other ultrasonic parameters compressional v p and shear v s wave velocities velocity ratio v p v s waveform energy and temporal attenuation the sensitivity of each ultrasonic parameter was compared by measuring 300 samples from ten different types of rock each type was selected according to its mineralogy calcite and or dolomite rock and structural complexity homogeneous fractured brecciated foliated or laminated samples were subjected to weathering tests thermal shock and salt crystallisation tests in order to study the sensitivity of both ultrasonic parameters during fracture initiation fracture growth and rock fabric disintegration results show that although vp is the most widely used parameter the information it yields is extremely imprecise however the new parameter s is highly sensitive to the petrographic characteristics of rocks as well as to the presence of individual defects fractures vugs or disintegrated areas moreover the most significant aspect of s is that its values fall between two fixed limits 0 db cm and 20 db cm a rock with a s value close to 0 db cm is an unweathered homogeneous and good quality rock whilst a s value higher than 12 db cm indicates extreme decay i e open fractures developed vugs and or disintegrated areas

development of the alluvial and lacustrine terraces on the northern margin of the hetao basin inner mongolia china implications for the evolution of the yellow river in the hetao area since the late pleistocene abstract terrace formation processes can reflect the evolution of large rivers the hetao basin is a floodplain of the yellow river and there are two to three terraces that extend e w on the northern margin based on a detailed field geological survey and measurement of the terrace sections combined with sedimentological and chronological analyses we reconstructed the developmental processes of the three terraces and inferred that three river terraces were formed by the yellow river the osl dating results show that the time of deposition of terrace 3 was prior to 118 ka bp subsequently the terrace began to experience incision and formed the geomorphic surface of terrace t3 similarly terrace 2 and terrace 1 were mainly deposited from 109 and 59 ka respectively and began to be incised prior to 71 and 46 ka respectively the three terraces in the northern hetao basin are the products of the combined actions of climatic shifts and tectonic uplift the yellow river s evolutionary history in the hetao area since the late pleistocene is discussed before about 120 ka bp the yellow river may have flowed through the northern hetao basin between 110 and 70 ka bp the yellow river experienced at least two changes between river and lake sedimentation from 60 to 50 ka a very large river connected lake of the yellow river was developed in the hetao basin after 50 ka the hetao river connected paleolake of the yellow river gradually dried

surface hardness as a proxy for weathering behaviour of limestone heritage a case study on dated headstones on the isle of portland uk this study estimates stone weathering rates using in situ surface hardness testing surface hardness changes are precursors to erosion and may be utilized to describe stone weathering behaviour the method proposed here complements previous approaches to determining stone weathering rates by surface loss change a time series covering 1 248 years of exposure is investigated using a sample of 12 headstones in two nearby cemeteries using an equotip d surface hardness tester rates of change in surface hardness for top and bottom sections of the headstones were determined and the data evaluated using robust nonparametric statistical methods when considering all headstones as one time series nonlinear behaviour is observed with rates of decline in surface hardness slowing over time however breakpoint analysis shows a breakpoint at c 100 years with higher rates of surface hardness decline as measured by qc 50 the regression coefficient for 0 50 quantile regression up to that point and lower rates thereafter up to c 100 years surface hardness declines more rapidly in the top versus bottom sections possible explanations for the differing rates in surface hardness changes are a inherent natural stone variability and or different weathering stress history b the use of two different portland limestone varieties c synergistic effects of microclimates and lichen cover in order to gain a deeper insight into stone weathering behaviour future studies could combine surface hardness measurements with surface change methods such as micro erosion meter and lead plug index over short and long term time series on architectural heritage under real world conditions

new field evidence bearing on the origin of the el laco magnetite deposit northern chile a reply the el laco magnetite deposit has been interpreted as lava flows and feeder dikes formed from iron oxide magma but more recently as a product of metasomatic replacement open pit exposure created at laco sur during the 1990s reveals that the massive magnetite contains magnetite veined blocks and smaller fragments of altered andesitic volcanic rock clearly supporting the replacement origin open space growth of magnetite and pyroxene along the walls of chimney structures and veins within magnetite indicates precipitation from aqueous fluid rather than from gas alone the native sulfur bearing cristobalite alunite alteration widespread at el laco and broadly contemporaneous with magnetite formation is recognized as part of a steam heated horizon generated in the vadose zone above a paleowater table consequently the magnetite replacement must have taken place beneath the paleowater table but probably 300 m beneath the paleosurface thus magnetite deposition at or immediately beneath the paleosurface is precluded the main outstanding question is how hot hypersaline brine the probable ore forming fluid at el laco attained such shallow crustal levels within a high volcanic edifice without undergoing the extensive groundwater dilution documented from most shallowly preserved hydrothermal systems

the schmidt hammer in rock material characterization the schmidt hammer provides a quick and inexpensive measure of surface hardness that is widely used for estimating the mechanical properties of rock material however a number of issues such as hammer type normalization of rebound values specimen dimensions surface smoothness weathering and moisture content and testing data reduction and analysis procedures continue to influence the consistency and reliability of the schmidt hammer test results this paper presents a a critical review of these basic issues and b the results of tests conducted on granitic rocks of various weathering grades in the light of the conclusions of this review it was found that a very good correlation exists between l and n hammer rebound values and that both hammers are fairly sensitive to the physical properties particularly to dry density though less so to effective and total porosities the n hammer producing a lesser scatter in the data proved to be more efficient than the l hammer in predicting uniaxial compressive strength and young s modulus the exponential form of the correlation curves was found to reflect microstructural changes during the course of weathering and the differences in the probing scales or mechanisms in the means of measuring these mechanical properties and could be generalized to other crystalline igneous rocks the possibility of predicting weathering grades from rebound values was also explored the changes in the rebound values during multiple impacts at a given point produced a better indication of the weathering grade than a single impact value it was concluded that increasing the impact energy and plunger tip diameter should significantly reduce the scatter in coarse grained weathered rocks and hence improve the reliability of the schmidt hammer as a rock material characterization tool

low impact surface hardness testing equotip on porous surfaces advances in methodology with implications for rock weathering and stone deterioration research 2015 john wiley and sons ltd the equotip surface hardness tester is becoming a popular method for rock and stone weathering research in order to improve the reliability of equotip for on site application this study tested four porous limestones under laboratory conditions the range of stone porosity was chosen to represent likely porosities found in weathered limestones in the field we consider several key issues i its suitability for soft and porous stones ii the type of probe required for specific on site applications iii appropriate non parametrical statistical methods for equotip data iv sufficient sampling size this study shows that the equotip is suitable for soft and porous rock and stone from the two tested probes the dl probe has some advantages over the d probe as it correlates slightly better with open porosity and allows for more controlled sampling in recessed areas and rough or curved areas we show that appropriate sampling sizes and robust non parametric methods for subsequent data evaluation can produce meaningful measures of rock surface hardness derived from the equotip the novel hybrid dynamic hardness a combination of two measuring procedures single impact method sim and repeated impact method rim has been adapted and is based on median values to provide a more robust data evaluation for the tested stones in this study we propose a sample size of 45 readings for a confidence level of 95 this approach can certainly be transferred to stone and rock with similar porosities and hardness our approach also allows for consistent comparisons to be made across a wide variety of studies in the fields of rock weathering and stone deterioration research

average pleistocene climatic patterns in the southern central andes controls on mountain glaciation and paleoclimate implications abstract despite elevations of 5000 6800 m modern glaciers occur along the southern puna plateau and the northern sierras pampeanas in the southern central andes the modern snowline rises from 5100 m in sierra aconquija to 5800 m in the puna as a result of a westward decrease in precipitation from 450 to less than 100 mm yr during the pleistocene these arid highlands experienced multiple cirque and valley glaciation that likely postdate the last interglacial period although lack of age control prevents an absolute chronology glaciation in the puna and along the eastern puna edge produced a 300 m pleistocene snowline psl depression while in the sierras pampeanas the psl depression was at least 900 m the greater psl depression in the sierras pampeanas is best explained by a combination of cooling and increase of easterly moisture whereas the psl depression in the puna appears more sensitive to moisture increases than temperature previously glaciations in this region have been explained by increa

late quaternary vegetational change in the central peruvian andes abstract new fossil pollen records from the central peruvian andes at elevations above 4000 m including pollen concentration data and additional radiocarbon dates provide information on late quaternary vegetation change for the region a pollen assemblage typical of superpuna plus low pollen concentrations and organics in the late glacial section of laguna tuctua indicate a cold dry climate but strong evidence for a late glacial climate reversal i e the younger dryas is not presently confirmed an abrupt increase in urticales pollen as compositae and polylepis acaena type pollen decline signals the beginning of the holocene subsequent increases in urticales and plantago rigida type pollen point to increased moisture as well as higher temperatures from about 11 000 to 7000 yr b p a possible correlation exists between the rapid expansion of puna and closed continuous forest and the rise in importance of camelids in the early holocene in the mid holocene plantago rigida cushion bogs and continuous montane forest elements decline suggesting a drier climate grasses and cheno ams then increase reaching maxima about 4000 yr b p pastoralism and agriculture are thought to have developed at this time according to ethnobotanical studies from this area and pollen evidence seems to support these findings between 3000 and 2000 yr b p pollen percentages of poaceae plantago rigida type and other local taxa decline as glacial activity was renewed in the higher mountains zea mays is present by 2000 yr b p and pollen of weeds and secondary successional plants associated with increasing agricultural disturbance are evident

glacier readvances in the andes at 12 500 10 000 yr bp implications for mechanism of late glacial climatic change radiocarbon dates from two sites in the andes ecuador and peru confirm that glaciers culminated a readvance after 11 000 yr bp a moraine stage equivalent in altitude and position relative to existing glaciers is present in most glacierized ranges but its age is equivocal broadly limiting dates from colombia and peru suggest that the stage may be late glacial as it is younger than 12100 yr bp but formed before the early holocene in southern chile a comparable moraine stage is older than ca 9100 yr bp andean glaciers appear to have advanced at least twice during the late glacial interval glacier reconstruction from these moraine limits suggests depression of the equilibrium line altitude by at least 300 400 m in the northern and north central andes and possibly less than this farther south late glacial climatic change occurred globally and possibly reflects north atlantic temperature and circulation changes forced by deglaciation of the northern ice sheets migrations north and south of the atlantic polar front and the switching off and on of a dust pump in low midlatitudes

late glacial and late holocene moraines in the cerros cuchpanga central peru abstract small ice fields on the western cordillera northeast of lima were expanded to three times their present size in the recent past and the regional snow line was probably about 100 m lower than it is today outwash from the expanded glaciers formed deltas of silt in valley bottom lakes when the ice lobes retreated the reduced outwash was trapped behind recessional moraines and the clear meltwater infiltrated into the limestone bedrock and emerged at the heads of the deltas in spring pools the delta surfaces then became covered with peat and radiocarbon dates for the base of the peat 1100 70 and 430 70 yr b p for two different deltas indicate that the maximum ice advance was older than those dates and thus older than the little ice age of many north temperate regions much older moraines date from expansion of the same local summit glaciers to even lower levels in the main valleys which had previously been inundated by the cordilleran ice field the cordilleran deglaciation and this expansion of local glaciers probably occurred between 12 000 and 10 000 yr ago on the basis of slightly contradictory radiocarbon dates

isrm suggested method for determination of the schmidt hammer rebound hardness revised version with its portable simple and affordable attributes the schmidt hammer sh is an ideal index apparatus which underlies its increasing popularity and expanding range of applications the sh rebound hardness value r is perhaps the most frequently used index in rock mechanics practice for estimating the uniaxial compressive strength ucs and the modulus of elasticity e of intact rock both in laboratory conditions and in situ the sh is also widely used for estimating the ucs of discontinuity walls and assessing the workability excavatability and boreability of rocks by mechanical means cutting polishing milling crushing and fragmentation processes in quarrying drilling and tunneling

non destructive testing for the assessment of granite decay in heritage structures compared to quarry stone several types of granite found in two architectural heritage monuments were assessed with two non destructive portable techniques schmidt hammer rebound and ultrasound velocity vp similar assessments were conducted on the rock from which the granite was originally quarried for comparison the results obtained which revealed the existence of a direct correlation constitute a useful indication of decay particularly if the approximate dates of construction are known and conversely if they are not such stone assessments may provide a rough estimate of when the structure was built both of these convenient portable and non destructive techniques may be used as reliable indicators of the degree of stone decay

the effect of weathering on pore geometry and compressive strength of selected rock types from turkey weathering processes cause important changes in rock porosity besides porosity distribution of pore sizes is significant for the identification of changes due to rock weathering and its effects on fabric the formation of secondary porosity in different types of rock taken from different parts of turkey was examined and the results are presented in this paper the aim of this study was to observe changes in porosity due to weathering effective porosity mercury intrusion porosimetry and optical and scanning electron microscopy were used to evaluate the changes in pore geometry of the rocks additionally the dry density water absorption and uniaxial compressive strength of the rocks at different weathering stages were determined analysis of experimental data showed that microstructure of the rocks in relation to weathering is the main feature which controls their physical and mechanical properties the study revealed that fabric characteristics particularly the pore and fracture geometry are very important characteristics for assessment of the behaviour of weathered rock

mineralogy and provenance of the clastic deposits of the modern intertidal environment of the northern arabian gulf abstract a detailed mineralogical investigation was carried out to determine the composition genesis and potential sources of the clastic deposits covering the modern intertidal environment of kuwait the study area can be broadly divided into northern and southern geomorphic provinces the intertidal zone of the northern province is characterized by wide mudflats covered by silicate dominated sediments with subordinate amounts of carbonates mostly of the low mg calcite and dolomite variety the southern province is marked by relatively steep sandy beaches fronted by narrow to moderately wide rocky intertidal flats partially covered by sand the southern sediments are dominated by aragonite and high mg calcite with less abundant quartz and feldspars erosion and abrasion of coastal deposits tertiary quaternary bedrock and coastal ridges fill material and beach rocks by waves and currents is believed to represent the most important source of the intertidal sediments especially the coarse fraction aeolian material transported as bedload from local sources and as suspended load from regional sources particularly the mesopotamian plain to the north is another important source contrary to common belief of all potential sources the euphrates tigris river system shatt al arab was found to have the least impact on the sedimentation regime of the modern intertidal environment of the northwestern arabian gulf its contribution is probably restricted to fine silt and clay fractions and even then only under flood conditions reworking of the ancient deltaic and estuarine deposits submerged in the northern arabian gulf is probably a more important contributor to the fine fraction of the study area than the shatt al arab discharge spatial variations in the abundance and distribution of the mineral constituents in the intertidal sediments indicate that the relative importance of the above sources varies from one area to another along the kuwaiti coast

geological constraints on the kinematics and fault plane solution of the quiches fault zone reactivated during the 10 november 1946 ancash earthquake northern peru the ancash earthquake of 10 november 1946 mw 6 8 produced surface faulting along the quiches normal slip fault field studies reported discontinuous nw se to nnw sse striking seismic scarps that displace quaternary glacial moraines and outwash as well as mesozoic sedimentary rocks structural analyses show that the 1946 normal displacement was accompanied by a small left lateral slip component morphological analysis of the fault scarp and observations in a trench excavated across the scarp show evidence of a single normal fault displacement before the 1946 seismic event that offset late pleistocene glacial moraines this indicates an approximate recurrence interval of more than 13 000 1 000 years for the major events suggesting a rate of net vertical displacement on the fault of less than 0 25 mm yr kinematic analysis along the quiches fault in comparison with other regional studies suggests that the state of stress in the high andes is regionally and locally homogeneous with only minor changes in the stress directions adjacent to major structures such as the maranon thrust and fold belt the minimum horizontal stress 3 axis is oriented n10 25 e the intermediate horizontal stress 2 axis is oriented n100 115 e and the maximum stress 1 axis is vertical we suggest that the 60 sw dipping quiches surface fault plane is connected at depth to a low angle dipping fault plane this seismic fault is a reactivated thrust fault of the tertiary maranon thrust and fold belt

predicting water permeability in sedimentary rocks from capillary imbibition and pore structure this study was financed by the spanish ministry of science and innovation cgl2011 25162 a pre doctoral research fellowship was awarded to c pla for this project

rock fabric heterogeneity and its influence on the petrophysical properties of a building limestone lede stone belgium as an example lede stone is an important historical stone in belgium with many ceased and disappeared historical quarries owing to its geological nature this stone exhibits considerable variation in petrophysical properties three macroscopical different facies from the solely remaining quarry area in balegem belgium were profoundly characterized for their pore network properties and petrophysical properties the pore network was exhaustively studied combining water imbibition under vacuum mercury intrusion porosimetry and x ray computed microtomography the three facies not only have a strong difference in total porosity but also differ in terms of pore connectivity and pore size distribution linked to the variability in microfacies this has profound implications on the water transfer properties such as atmospheric water absorption capillary water absorption om nidirectional drying and water vapor resistance the petrophysical behavior is illustrated with a salt ageing test the results can be used for restoration and conservation of lede stone in the built cultural heritage

numerical modeling of moisture transport in sandstone the influence of pore space fabric and clay content in the present study a numerical modeling of moisture distribution under real climate conditions within sandstone monoliths is accomplished based on detailed material specific transport and storage functions the impact of lithology and pore radii distributions is modeled with consideration of 1 the single sandstone monolith 2 the sandstone monolith with clay layers and 3 the sandstone monolith with clay layers and hydrophobic treatment the results reveal that the unimodal equal pore radii distribution of the quartz arenite promotes quickly a capillary water uptake during driving rain liquid stage but due to its missing smaller capillaries a high drying velocity leads to an almost dry pore space since moisture can only be absorbed via gaseous stage e g during summer on the contrary the sublitharenite with a unimodal unequable pore radii distribution is characterized by a distinctly higher water content since in addition smaller pores also allow the absorption of moisture via sorption moreover the high clay content promotes a retarded interaction with the environment which is also reflected by the high vapor diffusion resistance the highest water content shows the feldspathic litharenite with highest clay content and bimodal pore size distribution here over nine magnitudes of water transporting pores is involved at water transport and storage results also reveal that moisture accumulations during droughts trace the deterioration shape of rounding for all sandstones highest annual fluctuations are observable within the rim zone of the monolith while the center is characterized by more stable moisture content which mainly depends on rising water content of the bedrock the presence of clay layers has for each sandstone specific consequences however within the whole sandstone the stress index is increased and stress location is displaced to the boundaries of clay layers results of modeling the hydrophobic treatment reveal that this conservation strategy is only useful for sandstones where all moisture is absorbed in liquid stage why then all water absorption is hindered in case of sandstones with bimodal and unimodal unequal pore size distributions moisture uptake is possible also via sorption accordingly moisture accumulates behind the zone of hydrophobic treatment this finally will lead to stress transfer to the outer rim during salt or ice crystallization and will be responsible for flaking

cenozoic glaciation in the southern hemisphere with the end of glaciation in gondwana in early permian time a prolonged interval began when the earth was without ice sheets though not necessarily free of mountain glaciers not until sometime during the tertiary era did ice sheets build up once more first in antarctica and later in the northern hemisphere the fundamental cause of the cooling that led to the formation of the antarctic ice sheet and eventually to major glaciation in lower latitudes is generally held to have been the increasing thermal isolation of antarctica as australia and later south america separated from it allowing zonal oceanic circulation to develop rifting between australia and antarctica began between 1 10 and 90 m y ago cande mutter 1982 but not until much later probably sometime between 30 and 25 m y ago had it progressed far enough for deep circulation to begin as the south tasman rise cleared north victoria land kennett et a1 1974 kennett 1977 weissel et ai 1977 however antarctica did not reach its present high level of thermal isolation until south america had separated from it enabling the antarctic circumpolar current to become established savin et ai 1975 according to barker burrell 1977 1982 coherent spreading between the antarctic peninsula and tierra del fuego started about 29 m y ago and deep circulation began 23 5 2 5 m y ago thereafter increasing in volume the initial ice fields and ice caps that later expanded to become the

experimental investigation on the performance of schmidt hammer test in durability assessment of carbonate building stones against freeze thaw weathering although schmidt hammer test has been widely used for assessment of weathering state of rocks its application for evaluation of rock durability remains rare this study aims at investigating the performance of the schmidt hammer test in the durability assessment of carbonate building stones against frost weathering for this purpose nine types of carbonate rocks were collected from various quarries of iran and subjected to a series of tests including determination of petrographical physical mechanical ultrasonic and rebound hardness properties moreover long term weathering test of freeze thaw up to 100 cycles were carried out and ultrasonic detection was used to detect the weathering induced damages of rocks in ultrasonic detections ultrasonic parameters of maximum amplitude amax spatial attenuation s and compressional wave velocity vp were determined before and after freeze thaw tests and then their change rates were determined the change rates of amax s and vp including ka k and kp respectively were considered as the functions of the degree of the frost induced damages of rocks and consequently as indications of the rock durability results showed that there are close correlations between the schmidt hammer rebound value rn and ka k and kp however the correlation between rn and kp was weaker than those between rn and ka and k because of the disproportionate response of vp to the rock deterioration it was concluded that the schmidt hammer test is capable to evaluate the durability of carbonate building stones and can be used for a rapid and onsite evaluation of rock durability at different quarry faces hence it allows selecting more durable rocks for different applications in new constructions and also in replacement works in historical sites

characterisation of monzogranitic batholiths as a supply source for heritage construction in the northwest of madrid abstract the church of the assumption of our lady in valdemorillo madrid spain is almost entirely built with granitoids the studies and analyses were focused on the oldest part of the building ghosts corner which will be restored and rehabilitated in the near future homogeneous monzogranite is the predominant granitoid used in the ghosts corner followed by granitic porphyry porphyrytic monzogranite gneiss and leucogranite the original quarries that supplied homogeneous monzogranites for the first construction stages correspond to blocks present in the monument s surroundings quarries that supplied the granitic porphyries correspond to the dykes located to east southeast of valdemorillo which are oriented n s in relation to their intrusion direction the combined use of ultrasonic velocity and schmidt hammer techniques allowed first selection of the most representative blocks and ashlars for sampling this reduced sampling to a minimum but yielded representative results for the whole building second the combined values were used to compare results for the building stones of the church to rocks from the surrounding quarries stones from the building showed lower ultrasonic and schmidt hammer values and higher porosity and water saturation values compared to the original quarry rocks the anisotropy indices are directly related to the decay processes in the stone spalling of homogeneous monzogranite and grain disintegration in granitic porphyries finally the methods applied are inexpensive easy to use and non destructive techniques very advisable properties when working with built heritage

late miocene earliest pliocene glaciation in southern argentina implications for global ice sheet history abstract in south america at latitude 47 s till was deposited sometime between 7 m y and 4 6 m y ago at a time when the local climate was colder than today s during this same interval glaciers extended to sea level in southeast alaska and widespread cooling of the ocean surface in middle latitudes worldwide marine regression and change in the oxygen isotopic composition of ocean water occurred from the last three events major late miocene expansion of the antarctic ice sheet has been inferred on the assumption that the history of north atlantic ice rafting precludes the existence of northern hemisphere ice sheets until 3 m y ago this is disputed first because precipitation in antarctica would probably have decreased at temperatures below today s second because the antarctic ice sheet cannot expand appreciably until buildup of northern hemisphere ice sheets has lowered sea level third because virtually no late miocene sediments are present at the labrador sea dsdp sites that are critical to the reconstruction of north atlantic ice rafting history and fourth because the scale of late miocene glaciation in alaska is at least permissive for simultaneous buildup of ice at similar latitudes further east if global ice sheet volume at the end of the miocene was greater than it is today by an amount that would have lowered sea level by several tens of meters the excess ice did not accumulate in antarctica but in the northern hemisphere chiefly in north america away from the atlantic coast

recent glacial history and paleoclimate of the peruvian bolivian andes abstract radiocarbon dates of glacial deposits in the peruvian bolivian andes are used to place the observed phases of glaciation in a common chronological framework the climatic conditions that may determine modern snowline are examined in order to understand the types of climatic forcing to which glaciers may have been sensitive in the past also considered are independent proxies of climatic change including pollen sequences lake level history and ice core data late pleistocene glaciation in central peru between 24 ka and 12 ka bp appears to have occurred during colder and perhaps drier conditions in bolivia a glacial maximum is dated to phases of late holocene glaciation in peru that correspond in part to the little ice age in the northern hemisphere appear to have been caused by a combination of colder and wetter conditions an overall warming trend may be the cause for the retreat of many glaciers in the region since the mid 19th century

regional synthesis of last glacial maximum snowlines in the tropical andes south america the modern glaciers of the tropical andes are a small remnant of the ice that occupied the mountain chain during past glacial periods estimates of local last glacial maximum lgm snowline depression range from low e g 200 300 m in the junin region peru through intermediate 600 m at laguna kollpa kkota in bolivia to high e g 1100 1350 m in the cordillera oriental peru although a considerable body of work on paleosnowlines exists for the tropical andes absolute dating is lacking for most sites moraines that have been reliably dated to 21 cal kyr bp have been identified at few locations in the tropical andes more commonly but still rarely moraines can be bracketed between about 10 14 c kyr 11 5 cal kyr bp and 30 14 c kyr bp typically only minimum limiting ages for glacial retreat are available cosmogenic dating of erratics on moraines may be able to provide absolute dating with sufficient accuracy to identify deposits of the local lgm ongoing work using cosmogenic 10 be and 26 al in peru and bolivia suggests that the local lgm may have occurred prior to 21 cal kyr bp r 2005 elsevier ltd and inqua all rights reserved

late quaternary glaciation of the cordillera real bolivia glacial geological studies in tropical mountain areas of the southern hemisphere can be used to address two issues of late pleistocene climate change the global synchroneity of deglaciation and the magnitude of temperature reduction in the tropics radiocarbon dates from the cordillera real and from other areas in peru and bolivia suggest that late pleistocene glaciation culminated between 14 000 and 12 000 yr bp followed by rapid deglaciation because deglaciation was apparently synchronous with that in northern hemisphere regions insolation change at high latitudes may not have been the only factor that produced global deglaciation at this time late pleistocene glaciation in the cordillera real culminated when precipitation was 200 mm yr 1 higher and temperatures were 3 5 1 6 c lower than today this produced an equilibrium line altitude depression of about 300 100 m on the western side of the cordillera prior to this conditions were drier and probably at least as cold however the lack of moraines in the cordillera real dated to the last glacial maximum ca 18000 yr bp precludes using the equilibrium line altitude method to quantitatively evaluate the discrepancy between warm sea surface temperatures and cold terrestrial conditions reconstructed with other proxies for this time period

weathering behaviour and construction suitability of dimension stones from the drei gleichen area thuringia germany the construction suitability of a dimension stone depends on its weathering properties along with the petrology and the petrophysical properties the aim of this study was to evaluate the suitability of the dimension stones from the drei gleichen area for construction and replacement purposes in total six sandstones ingersleben wachsenburg hindfelden seeberg rohnberg gleichenberg upper triassic as well as two carbonates wachsenburg sinter quaternary wandersleben dolomite middle triassic were analysed the results from our laboratory and on site studies of the dimension stones show that rocks from the same stratigraphic layer like the sandstones from the upper triassic can show major differences in their petrophysical and weathering properties these differences are attributed to their different diagenesis resulting e g in varying pore space water balance and strength properties the pore size distribution can be divided into four different groups based on their occurring maxima and micropore content the determined water balance properties as well as moisture expansion and salt attack depend on these groups next to this the mineralogical composition significantly influences the weathering resistance sandstones with a high content of altered lithoclasts show a high amount of moisture expansion low strength and in consequence a low weathering resistance against salt attack based on the results of the present study an evaluation of construction suitability could be accomplished from the analysed sandstones only the seebergen sandstone is suitable for construction purposes due to its good availability good strength properties high compressive and tensile strength low softening degree as well as a low porosity furthermore the wachsenburg sandstone also shows good petrophysical and petrological properties but exploitable deposits are too sparse to be of commercial interest from the carbonates the wachsenburg sinter shows very suitable rock parameters but only sparse outcrops occur which are not appropriate for mining

the pore system of sedimentary rocks as a key factor in the durability of building materials abstract we studied the pore system of six different types of sedimentary stone two limestones two sandstones one dolostone and one travertine techniques based on the direct observation of the pore system optical and scanning electron microscopes digital image analysis were combined with others used for indirect characterization mercury intrusion porosimetry n 2 adsorption hydric tests and vapour permeability in addition we performed accelerated decay tests to determine the durability of the stones and to check the consistency of the results obtained in the pore system study digital image analysis allowed us to calculate the pore size distribution and the total porosity digital image analysis always gave higher values for total porosity than those determined by porosimetry and hydric tests which only measure open porosity the density values were congruent with the mineralogy of the stones the stone that obtained the best results in the various tests in terms of its petrophysical parameters was dolostone while the worst performance was by one of the two limestones these results were confirmed by the decay tests the combined use of these different techniques gave us an accurate interpretation of the pore systems of the six different stones and also enabled us to correct misleading interpretations caused by the limitations of using one single technique our findings also provide useful information to help prevent the decay of these stones

glaciation in the andes during the lateglacial and holocene this review updates the chronology of andean glaciation during the lateglacial and the holocene from the numerous articles and reviews published over the past three decades the andes which include some of the world s wettest and driest mountainous regions offer an unparalleled opportunity to elucidate spatial and temporal patterns of glaciation along a continuous 68 degree meridional transect the geographic and altitudinal extent of modern glaciers and the sensitivity of both modern and former glaciers to respond to changes in specific climatic variables reflect broad scale atmospheric circulation and consequent regional moisture patterns glaciers in the tropical andes and in the mid latitude andes are likely to have been far more sensitive to changes in temperature than glaciers in the dry subtropical andes broad scale temporal and spatial patterns of glaciation during the lateglacial are apparent in the southernmost andes the lateglacial chronology appears to have a strong antarctic signature with the best dated moraines correlating closely with the antarctic cold reversal the southernmost andes do not appear to have experienced a significant ice advance coeval with the younger dryas yd climatic reversal at the other end of the andes from w 0t o 9 n a stronger yd connection may exist but critical stratigraphic and geochronologic work is required before a yd ice advance can be fully demonstrated in the central andes of peru well dated moraines record a significant ice readvance at the onset of the yd but ice was retreating during much of the remaining yd interval the spatial temporal pattern of holocene glaciation exhibits tantalizing but incomplete evidence for an early to mid holocene ice advance s in many regions but not in the arid subtropical andes where moraines deposited during or slightly prior to the little ice age lia record the most extensive advance of the holocene in many regions there is strong evidence for neoglacial advances in the interval between 1 0 and 2 5 ka moraines that correlate with the lia of the northern hemisphere are seen in all presently glacierized mountain ranges most of these date to within the past 450 years outboard of these moraines in many regions are moraines of a slightly more extensive advance that occurred several hundred years prior to the onset of the lia priorities for future work include filling in several prominent spatial gaps in the distribution of chronologic studies for the lateglacial these gaps include the arid regions of northern chile and argentina the southern peruvian andes between 11 5 and 13 5 s and the andes of northern peru and

the use of the schmidt hammer and equotip for rock hardness assessment in geomorphology and heritage science a comparative analysis rapid field based measurements of rock hardness are of use in investigating many geomorphological and heritage science problems several different methods are now available for taking such measurements but little work has been done to assess their comparability and strengths and weaknesses we review here the capabilities of two types of schmidt hammer classic n type and silver schmidt bl type alongside two types of equotip standard type d and piccolo for investigating rock hardness in relation to rock weathering on various types of sandstone and limestone as well as basalt and dolerite whilst the two schmidt hammers and the two equotips show comparable results when tested at 15 individual sites interesting differences are found between the equotip and schmidt hammer values which may reveal information about the nature of weathering on different surfaces operator variance is shown to be an issue in particular for the equotip devices which also exhibit higher variability in measurements and necessitate larger sample sizes carborundum pre treatment also has varying effects on the data collected depending on the nature of the surface studied the equotip devices are shown to be particularly useful on smaller blocks and in situations where edge effects may affect schmidt hammer readings we conclude that whilst each device contributes to geomorphological research they do not necessarily produce comparable information indeed using schmidt hammer and equotip in combination and looking at any differences in results may provide invaluable insights into the structure of the near surface zones and the nature of weathering processes copyright 2010 john wiley sons ltd

a review of lateglacial pollen records from ecuador and peru with reference to the younger dryas event abstract published biostratigraphic records from ecuador spanning the lateglacial period of approximately 13 000 to 10 000 bp lack radiocarbon dates delineating the younger dryas and records with extrapolated dates do not exhibit evidence of a climatic reversal for peru fossil pollen data from four sites suggest one and possibly two climatic oscillations in the lateglacial but only one site laguna junin has dates that delimit a short term climatic change and this occurs between 12 000 and 11 000 bp pollen records from laguna baja and rio blanco pond give the strongest indication of a climatic reversal but bracketing dates are not available other pollen records from peru have tenuous dating or data and do not support a lateglacial climatic reversal at the time of the younger dryas

a late glacial holocene pollen record from the eastern andes of northern peru abstract a pollen and sediment record of a core 4 2 m long from laguna baja 7 42 s 77 32 w 3575 m in the cordillera oriental of northern peru suggests several episodes of major vegetational and climatic change over the past 13 000 yr the oldest pollen assemblage consists of a mixture of paramo elements tropical alpine vegetation including high percentages of poaceae 40 that decline upward moist montane forest compositae and polylepis and wet montane forest e g hedyosmum and podocarpaceae organic carbon content range from 60 with high percentages of jamesonia a fern characteristic of paramo and decreasing values of plantago tubulosa and the wet montane forest elements hedyosmum and podocarpaceae charcoal percentages are at a maximum during this period magnetic susceptibility and sand percentages are high and percentages of organic matter are low several explanations for these changes are possible including a reduction in temperature and moisture more frequent periods of aridity with increased fires or natural succession the holocene record begins with pronounced increases in organic carbon and pollen of wet montane forest primarily hedyosmum podacarpaceae and urticales high values of podocarpaceae pollen 35 and a decline in charcoal suggest temperature and moisture levels above modern day values wet montane forest pollen remain high and charcoal values are low from about 10 000 to 6000 yr b p suggesting that warm and moist conditions prevailed for about 4000 yr subsequently podocarpaceae and urticales decline and for a brief time alnus is prominent in the pollen record following the alnus maximum at about 5000 yr b p poaceae ambrosia and chenopodiaceae amaranthaceae become frequent increased paramo and disturbance indicator pollen suggest increased anthropogenic activities in this region from the middle holocene to the present