palustrine carbonates and the florida everglades towards an exposure index for the fresh water environment abstract palustrine carbonates are shallow fresh water deposits showing evidence of subaqueous deposition and subaerial exposure these facies are common in the geological record the intensity of modification is highly variable depending on the climate and the length of emergence palustrine limestones have previously been interpreted as marginal lacustrine deposits from fluctuating low salinity carbonate lakes but several problems remain with existing facies models 1 palustrine carbonates possess a lacustrine biota but commonly display fabrics similar to those of calcretes and peritidal carbonates 2 the co occurrence of calcrete horizons and karst like cavities is somewhat unusual and appears to indicate contemporaneous carbonate precipitation and dissolution in the vadose zone 3 the dominance of gray colors indicates water saturation apparently inconsistent with the evidence for strong desiccation overprint 4 profundal lake deposits are generally absent from palustrine sequences and sublittoral facies commonly make up only a small proportion of total thicknesses 5 no good modern analogue has been identified for the palustrine environment analogy with the florida everglades suggests a re interpretation of palustrine limestones not as pedogenically modified lake margin facies but as the deposits of extensive very shallow carbonate marshes the distribution of environments in the everglades is determined by the local hydrology reflecting the control of seasonal water level fluctuations and topography climate and topography were the main controls on deposition of ancient palustrine carbonates as in peritidal sequences aggradational cycles are capped by a range of lithologies evaporites desiccation and microkarst breccias calcretes lignite or coal horizons etc permitting interpretation of the climate careful analysis of lateral facies variations may permit reconstruction of subtle topography consideration of the florida everglades as a modern analogue for the palustrine environment has suggested the development of an exposure index for fresh water carbonates

modeling the backscatter response due to salt crust development the ers 1 synthetic aperture radar sar is shown to be highly sensitive to temporal variations in the mineral surface of the chott el djerid playa tunisia field measurements and modeling results confirm that the primary control on the backscatter response is due to salt crust development brine rich moisture exerts a secondary control the effect of temperature salinity and mineralogy are negligible an integral equation model iem solution with mean parameters accurately represents the observed behavior

did early man reach java during the late pliocene abstract homo erectus pithecanthropus reached java from the asian continent and became one of the oldest islanders in the world this article deals with the palaeomagnetic and 40 ar 39 ar dating of the lower lahar a layer located at the base of the fossil bearing series of the sangiran dome combined 40 ar 39 ar and palaeomagnetic data show that the deposition of the lower lahar marking the emergence of the first dryland at sangiran took place at the end and just after the olduvai subchron therefore c 1 7 million years can be considered as a maximal theoretical age for the arrival of the first hominids at sangiran

a detailed chronology of the australasian impact event the brunhes matuyama geomagnetic polarity reversal and global climate change a mechanism had been recently proposed to show how an impact event can trigger a geomagnetic polarity reversal by means of rapid climate cooling we test the proposed mechanism by examining the record from two high sedimentation rate 8 11 cm kyr deep sea sediment cores odp sites 767 and 769 from marginal seas of the indonesian archipelago which record the australasian impact with well defined microtektite layers the brunhes matuyama polarity reversal with strong and stable remanent magnetizations and global climate with oxygen isotope variations in planktonic foraminifera both odp cores show the impact to have preceded the reversal of magnetic field directions by about 12 kyr both records indicate that the field intensity was increasing near the time of impact and that it continued to increase for about 4 kyr afterwards furthermore the oxygen isotope record available from sediments at odp site 769 shows no indication of discernible climate cooling following the impact the microtektite event occurred in the later part of glacial stage 20 and was followed by a smooth warming trend to interglacial stage 19 thus the detailed chronology does not support the previously proposed model which would predict that a decrease in geomagnetic field intensity resulted from a minor glaciation following the impact event we conclude that the evidence for a causal link between impacts and geomagnetic reversals remains insufficient to demonstrate a physical connection

particle size characteristics of suspended sediment transported in meltwater from the gangotri glacier central himalaya an indicator of subglacial sediment evacuation abstract proglacial meltwater streams draining out of the himalayan glaciers carry considerable amounts of suspended sediment with a variety of particle sizes because of the supraglacial englacial and subglacial debris as well as formation of sediments from erosion by the movement of the ice this paper examines particle size transported in the proglacial meltwater stream of gangotri glacier for seven consecutive melt seasons may october 2000 2006 in order to provide information on i temporal variations in the particle size distribution ii texture and mineralogy of the sediments and iii origin and evacuation pattern of the sediments our results indicate dominance of silt size 0 002 0 06 mm particles 71 followed by sand size 0 06 0 6 mm particles 24 and clay size

evaporation of groundwater from arid playas measured by c band sar salt bearing groundwater evaporates within arid playas and roughens the surface during the summer months we show that it is possible to infer the rates of evaporation of groundwater using radar backscatter measurements using an empirically derived relationship between backscatter coefficient and surface roughness a model of how surface roughness changes with a continuous process of halite crystal efflorescence and an assumed value for the salinity of the regional groundwater we calculate the volumetric rate at which the groundwater must have evaporated the method is illustrated with data from the european remote sensing 1 satellite synthetic aperture radar sensor that imaged the chott el djerid playa in southern tunisia from 1992 to 1993 independent measurements and calculations indicate that the radar method overestimates the rate of evaporation the reasons for this probably lie in the assumptions about the salt budget of the groundwater or the model of how the salt crust roughens with time

classification of paleosols despite increased interest in paleosols during the past decade no satisfactory classification is in current use presented here is a largely descriptive classification system that utilizes those pedogenic features that have the highest preservation potential in the rock record emphasized in the classification are morphological and mineralogical features that are easily recognizable in the field and through the petrographic microscope the classification is based on evaluation of the relative prominence in a paleosol of six pedogenic features or processes organic matter content horizonation redox conditions in situ mineral alteration illuviation of insoluble minerals compounds and accumulation of soluble minerals the most prominent of these six features processes provides the key to classifying a paleosol into one of nine orders four of the order names are borrowed from soil taxonomy histosol spodosol oxisol vertisol whereas the other five order names are presented here for the first time calcisol gypsisol gleysol argillisol protosol the orders may be preceded by one or more subordinate modifiers that describe other important features of the paleosol the classification is relatively easy to apply to the rock record and should enhance communication and aid in the standardization of terminology

landscape development preceding homo erectus immigration into central java indonesia the sangiran formation lower lahar abstract the sangiran dome is the primary stratigraphic window for the solo basin a coastal feature on the pliocene pleistocene sunda subcontinent south margin in the dome the lower lahar unit llu is a lahar type debris flow overlying near shore marine sediments the event that emplaced the llu likely originated from sector collapse on a neighboring volcanic edifice freshwater mollusc fossils in the llu indicate that swamps or shallow lakes lay between the edifice and the current dome area 40ar 39ar analyses on hornblende separates from six pumice lenses suggest that the llu was deposited as early as 1 90 0 02 ma the event resulting in deposition of the llu transformed late pliocene near shore marine environments into estuarine and marsh settings shortly thereafter glacioeustatic sea level falls completed the local transition to fully terrestrial environments that attracted homo erectus to southernmost sunda in the early pleistocene

a wrb based buried paleosol classification abstract present classification systems for buried paleosols are inadequately developed several classification systems for paleosols based on the us soil taxonomy have been developed recently but their use is still very limited we propose appilcation of the world reference base for soil resources which uses only substantial profile characteristics as a background for the development of a new buried paleosol classification the system was adapted for the use for buried paleosols dynamic criteria which could be altered by diagenesis were disregarded and the definitions of most horizons were modified a new prefix infra was applied for modified diagnostic horizons and properties and for refernce groups of buried paleosols as a result 11 diagnostic horizons 2 properties and 2 materials were left with their definitions and names 9 diagnostic horizons and 2 properties were modified and named with the prefix infra 14 diagnostic horizons 6 properties and 4 materials were excluded or joined with others and two new diagnostic horizons were proposed this relationship reflects the balance between stable and dynamic properties in the diagnostic criteria used by the wrb the number of soil units proposed for buried paleosols is fewer than for surface soils in the wrb 25 instead of 30 the use of wrb modifiers reflecting dynamic soil properties was tentatively recommended for the second level buried paleosols classification with prefixes pedo for pedogenically derived properties and dia for the properties caused by post burial processes the application of the proposed system to a set of paleosols previously described in the literature showed its utility for buried paleosol classification

geomorphological significance of ontario lacus on titan integrated interpretation of cassini vims iss and radar data and comparison with the etosha pan namibia abstract ontario lacus is the largest lake of the whole southern hemisphere of titan saturn s major moon it has been imaged twice by each of the cassini imaging systems imaging science subsystem iss in 2004 and 2005 visual and infrared mapping spectrometer vims in 2007 and 2009 and radar in 2009 and 2010 we compile a geomorphological map and derive a hydrogeological interpretation of ontario lacus based on a joint analysis of iss vims and radar sar datasets along with the t49 altimetric profile acquired in december 2008 the morphologies observed on ontario lacus are compared to landforms of a semi arid terrestrial analog which resembles titan s lakes the etosha pan located in the owambo basin namibia the etosha pan is a flat floored depression formed by dissolution under semi arid conditions of a surface evaporitic layer calcretes controlled by groundwater vertical motions we infer that ontario lacus is an extremely flat and shallow depression lying in an alluvial plain surrounded by small mountain ranges under climatic conditions similar to those of terrestrial semi arid regions channels are seen in the southern part of ontario lacus in vims and radar data acquired at a 2 years time interval their constancy in location with time implies that the southern portion of the depression is probably not fully covered by a liquid layer at the time of the observations and that they most probably run on the floor of the depression a shallow layer of surface liquids corresponding to the darkest portions of the radar images would thus cover about 53 of the surface area of the depression of which almost 70 is located in its northern part these liquid covered parts of the depression where liquid ethane was previously identified are interpreted as topographic lows where the alkanofer raises above the depression floor the rest of the depression and mostly its southern part is interpreted as a flat and smooth exposed floor likely composed of a thick and liquid saturated coating of photon absorbing materials in the infrared this hypothesis could explain its dark appearance both in the infrared and radar data and the persistence of channels seen on the depression floor over the time shorelines are observed on the border of ontario lacus suggesting past high stand levels of the alkanofer table the analogy with the etosha pan suggests that ontario lacus depression developed at the expense of a soluble layer covering the region dissolution of this layer would be controlled by vertical motions of the alkanofer table over the time during flooding events liquid hydrocarbons covering the depression floor would dissolve the surface layer increasing progressively the diameter of the depression on geological timescales during drought episodes liquid hydrocarbons of the underground alkanofer would evaporate leading to crystallization of evaporites in the pores and at the surface of the substratum and to the formation of the regional soluble layer the presence of specific landforms lunette dunes or evaporites is compatible with such evaporitic regional settings alternatively but not exclusively the surface soluble layer might have formed by accumulation on the ground of soluble compounds formed in the atmosphere

occurrence and distribution of sulfur in peat forming environments of southern florida abstract cores and surface samples of peats from the everglades mangrove region of southern florida were analyzed for total sulfur and pyritic sulfur these values were compared with the petrographic botanical components of the peats as determined from point counts of oriented microtome sections pyrite occurs as individual euhedral crystals loosely packed framboids and lenses or crusts of minute crystals framboids and minute crystals are often associated with organic matter and sometimes with bacteria and fungi pyrite tends to selectively occur in void spaces in or between peat tissues in samples containing very small amounts of pyrite framboidal pyrite is the prevalent form marine to brackish peats contain the highest pyrite and total sulfur contents with brackish peats generally containing more pyrite than marine peats pyrite tends to be lower in all peats within 30 cm of the surface whether marine or brackish burial of freshwater peats beneath marine or brackish peats tends to increase the total sulfur and pyritic sulfur in the underlying peats burial beneath brackish water clay rich deposits such as splays tends to increase total sulfur and pyritic sulfur in the underlying deposits more than burial beneath less clay rich deposits

early pleistocene 40ar 39ar ages for bapang formation hominins central jawa indonesia the sangiran dome is the primary stratigraphic window for the plio pleistocene deposits of the solo basin of central jawa the dome has yielded nearly 80 homo erectus fossils around 50 of which have known findspots with a hornblende 40 ar 39 ar plateau age of 1 66 0 04 mega annum ma reportedly associated with two fossils swisher c c iii curtis g h jacob t getty a g suprijo a widiasmoro 1994 science 263 1118 1121 the dome offers evidence that early homo dispersed to east asia during the earliest pleistocene unfortunately the hornblende pumice was sampled at jokotingkir hill a central locality with complex lithostratigraphic deformation and dubious specimen provenance to address the antiquity of sangiran h erectus more systematically we investigate the sedimentary framework and hornblende 40 ar 39 ar age for volcanic deposits in the southeast quadrant of the dome in this sector bapang kabuh sediments have their largest exposure least deformation and most complete tephrostratigraphy at five locations we identify a sequence of sedimentary cycles in which h erectus fossils are associated with epiclastic pumice from sampled pumice eight hornblende separates produced 40 ar 39 ar plateau ages ranging from 1 51 0 08 ma at the bapang sangiran formation contact to 1 02 0 06 ma at a point above the hominin bearing sequence the chronological sequence of 40 ar 39 ar ages follows stratigraphic order across the southeast quadrant an intermediate level yielding four nearly complete crania has an age of about 1 25 ma

the temporal variability of centimeter scale surface roughness in a playa dust source synthetic aperture radar investigation of playa surface dynamics abstract emission of mineral dust aerosols is highly dynamic in part due to variability in surface erodibility investigation of the variations of surfaces within dust source regions has the potential to elucidate the processes that control erodibility and to improve model representations of dust emission in this study we investigate surface temporal variability in the black rock playa nevada usa using synthetic aperture radar sar satellite data from between 2004 and 2010 the sar backscatter 0 observations of the playa surface are compared to weather station observations and temporally resolved measurements of water inundation derived from multi spectral modis satellite data the data illustrate that centimeter scale surface roughness on the playa is surprisingly heterogeneous over multi meter length scales and evolves dynamically on annual time scales interannual changes in surface roughness on the playa are quite large compared to the variability of surface roughness during the summer months july september suggesting that summer anthropogenic and aeolian processes are substantially less important than water related processes for controlling the evolution of the playa surface playa median 0 is relatively low in years with high annual precipitation 140 mm suggesting that surface water controls centimeter scale surface roughness and potentially erodibility spatially there is a relationship between 0 and the time of year at which a surface dries areas drying in july have significantly higher 0 than surfaces that dry earlier in the year suggesting that spatial heterogeneity in 0 is controlled by cycles of wetting and drying at the edge of the playa lake the implications in the black rock playa and potentially more broadly are that water is a critical factor controlling playa surface evolution and the annual time scale is crucial for investigations of playa erodibility

climate surface pore water interactions on a salt crusted playa implications for crust pattern and surface roughness development measured using terrestrial laser scanning sodium accumulating playas also termed sodic or natric playas are typically covered by polygonal crusts with different pattern characteristics but little is known about the short term hours dynamics of these patterns or how pore water may respond to or drive changing salt crust patterning and surface roughness it is important to understand these interactions because playa crust surface pore water and roughness both influence wind erosion and dust emission through controlling erodibility and erosivity here we present the first high resolution 10 3m hours co located measurements of changing moisture and salt crust topography using terrestrial laser scanning tls and infra red imagery for sua pan botswana maximum nocturnal moisture pattern change was found on the crests of ridged surfaces during periods of low temperature and high relative humidity these peaks experienced non elastic expansion overnight of up to 30 mm and up to an average of 1 5 mm night during the 39 day measurement period continuous crusts on the other hand showed little nocturnal change in moisture or elevation the dynamic nature of salt crusts and the complex feedback patterns identified emphasise how processes both above and below the surface may govern the response of playa surfaces to microclimate diurnal cycles

wetting and drying of australia over the past 300 ka alternately dry and wet climatic episodes across central and eastern australia during the past 300 ka have greatly affected australia9s rivers lakes and dune fields evidence of widespread climate and flow regime changes has been provided by 75 thermoluminescence tl dates and 18 u th dates from alluvial and eolian sediments fluvial conditions dominated part of the last two interglacials stage 5 and 7 resulting in large sand loads in rivers in the present simpson desert and southeastern australia during the last interglacial fluvial activity in central australia peaked at 110 ka stage 5 pluvial probably 5 10 ka behind world temperature and sea level maxima following the last late interglacial wet phase aridity associated with dune building spread from central australia toward its margins achieving greatest intensity during the last glacial maximum a less widespread wet phase identified at about 55 35 ka stage 3 subpluvial is associated with high lake levels and paleochannel activity in southeastern australia this tl record of variable continental aridity in australia correlates well with global changes including the variable eolian dust flux into central china the northern pacific ocean and antarctica

chinese loess and the paleomonsoon abstract this paper presents a general review of the recent research advances of the east asian paleomonsoon based mainly on studies of the loess soil sequences in the chinese loess plateau in the last 2 6 million years the paleomonsoonal history may be divided into about 166 events on a time scale of the earth s orbital variations during the last glacial period millenial scale oscillations of the monsoon system were prominent which can be fairly well correlated with the dansgaard oeschger cycles recognized in the greenland ice cores the monsoonal rainfall belt has experienced a wide repeated advance retreat change during the glacial interglacial cycles of the pleistocene both temporal and spatial changes of the monsoon system in the quaternary could have been linked closely to global ice volume variations

the late quaternary palaeogeography of mammal evolution in the indonesian archipelago abstract the quaternary faunal evolution for the indonesian archipelago reflects the unique relationship of each island with se asian mainland the recent sub faunas of sundaland kalimantan sumatra java and bali preserved broad connections with the se asian mainland during the latest glacial they are all balanced and show many mainland components alternatively wallacea sulawesi and the lesser sunda islands has always been geographically isolated from the mainland wallacea faunas thus remain unbalanced they lack large carnivores and endemic a significant turnover arrives throughout the region with pronounced global sea level recessions around 0 8 ma during the transition from early pleistocene ep to the middle pleistocene mp by way of comparison the palaeontological records of japan and taiwan also preserve this turnover with ep mp recessions bringing east asian mainland immigrants on java the earliest late pliocene to early pleistocene satir fauna indicates island conditions java became connected to the se asian mainland towards the end of the early pleistocene global cooling brought open woodlands on java an environment evidently preferred by homo erectus in the ci saat fauna and trinil h k fauna as ep mp sea level recessions created a wide corridor across the sunda shelf siwaliks and the se asian mainland terrestrial mammals invaded as is seen in the kedung brubus fauna the succeeding ngandong fauna maintains an open woodland character but shows some endemism homo erectus and stegodon trigonocephalus among others can be distinguished on a subspecies level the late pleistocene marks the earliest known tropical rainforest and the corresponding punung fauna is of chinese affinity with pongo hylobates and elephas maximus homo sapiens probably arrives at this point as well the youngest fossil faunas known from java are the still poorly known cipeundeuy fauna ca 30 ka and the holocene faunas from wajak and sampung while sulawesi and flores remained isolated throughout the quaternary only a limited number of terrestrial vertebrates arrived by crossing sea barriers endemic island faunas with pygmy elephantoids and giant tortoises were present during the early pleistocene ep mp sea level recessions allowed large to medium sized elephantoids to replace the dwarf species around the same time homo erectus appears on the island of flores modern faunas eventually replaced the middle pleistocene island faunas but the time frame has yet to be pinpointed sulawesi presents a unique case its current fauna holds no walanae representatives apart from the phalangers which must have come from the east the ancestors of all other large sulawesi land vertebrates fossil and extant reached the island by crossing the sunda sea as the south sulawesi fauna was stable until the middle pleistocene this area must have constituted a separate palaeo island some localized developments can be observed e g shortening of the metapodials in celebochoerus increasing hypsodonty in stegodon

australasian microtektites in the south china sea and the west philippine sea implications for age size and location of the impact crater abstract microtektites from two deep sea cores in the south china sea and the west philippine sea are identified as belonging to the australasian tektite strewn field based on the morphology chronostratigraphic occurrence and geographical location of these microtektites the higher concentrations of microtektites 1000 cm2 in the marginal seas of the western pacific with the peak concentration in the south china sea support the hypothesis of a large impact crater in indochina these two new occurrences lead to a more precise dating of the impact event at 793 ka whereas the size of the australasian source crater on the indochina peninsula is estimated to be 90 1 16 km introduction the australasian strewn field covering at least one tenth of the earth s surface is the largest and the youngest 0 77 0 02 ma izett and obradovich 1992 of the four known tektite strewn fields microtektites belonging to the australasian strewn field have been found in more than 40 deep sea cores throughout much of the indian ocean the western equatorial pacific ocean and the sulu celebes and philippine seas glass

reconstruction of a toposequence on volcanic material in the honje mountains ujung kulon peninsula west java abstract soil formation on weathered acid tuffs was studied in the national park of the ujung kulon peninsula west java indonesia in a toposequence in the honje mountains five principal types of materials layers were distinguished based on micromorphology mineralogy and chemistry the deepest part of all profiles corresponds to a saprolite derived from tertiary and pleistocene volcanic deposits locally showing the influence of pedoplasmation the overlying layer also contains saprolite fragments but later pedogenic processes are indicated by striated b fabrics and strong clay illuviation in most profiles formation of plinthite partly postdates clay illuviation a transition layer separates this part of the profile from the top layer which is characterised by a more open microstructure an undifferentiated b fabric and the presence of pumice gravel feldspars and pyroxenes originating from the krakatau ash fall after the uplift of the mio pliocene banten tuffs deep ferrallitic weathering was followed by a period of erosion during which stone lines were formed hitherto these have been attributed to occasional coarser tephra falls in a subsequent period of stability weathering and processes of pedoplasmation clay illuviation and plinthitisation were active during the eruption of the nearby mount krakatau in 1883 the area was covered by a layer of fresh ash which affected the composition and microfabric of the top layer leading to more andic properties no important erosion event followed the ash fall

the chott el djerid tunisia observation and discussion of a sar phase signature over evaporitic soils the presence of water in arid regions is correlated to large evaporitic deposits with high concentration of salts polarimetric synthetic aperture radar sar observations over such areas show high variations for both the amplitude and phase of the backscattered copolarized signal this is due to a large dynamic range for both surface roughness and dielectric constant parameters between the wet and dry seasons crystallized salt is rough and presents a low dielectric constant whereas saline water corresponds to smooth and conductive surfaces we observed a complete seasonal cycle over the chott el djerid playa in southern tunisia using the 5 6 ghz c band polarimetric sar on board radarsat 2 one sar image acquisition was performed every 24 days from february to september 2009 in addition to expected variations in the radar backscattered power we observed significant changes in the phase difference between horizontally and vertically polarized channels in order to explain such a phase effect we first considered the arguments of the fresnel reflectivity coefficient when approaching the brewster angle for materials presenting a high loss tangent a more complete analytical modeling derived from the integral equation model approach confirmed this hypothesis

pedo sedimentary dynamics of the sangiran dome hominid bearing layers early to middle pleistocene central java indonesia a palaeopedological approach for reconstructing pithecanthropus javanese homo erectus palaeoenvironment abstract fossil soils and pedosediments displayed in quaternary fossil bearing formations are an important proxy to describe the evolution of climates and environments through a study of the palaeosols in the sangiran dome a rich hominid bearing site of central java indonesia we characterized their record of terrestrialization through regional volcano tectonic activity and describe palaeoenvironments colonized by hominids the thick sedimentary formations of the sangiran dome are known to reflect the geological evolution of central java from the beginning of the quaternary until the middle pleistocene homo erectus fossils are found in the ca 1 5 ma sangiran or pucangan formation up to the ca 0 8 ma bapang or kabuh formation this study combines field surveying a micromorphological approach and palynological data the characterization of successive pedoclimatic contexts and toposequences helps in reconstruction of the local palaeogeography and climates mainly influenced by south eastern asia monsoon cycles that predominated during periods of palaeosol development the base of the upper sangiran member displays the earliest fully continental deposits corresponding to the development of an open landscape with wide coastal marshes and mangroves with a rain forest cover on the hinterland higher in the stratigraphic succession environments reflect a contrasting seasonal climate with a long dry season alternating with periods of more humid palustrine conditions a further tectonic uplift of the hill ranges bordering the solo depression in which the sangiran dome is located resulted in topographic changes and increasing palaeogeographic heterogeneity and therefore of soilscapes from the upper sangiran member to the bapang lower member erosion of soil cover caused the accumulation of pedosediments in topographic depressions these pedosedimentary deposits as well as volcanic ash accumulations were sudden and sometimes bury palaeoreliefs catena gilgai recurrent aridity proxies occur in the palaeosols found in the bapang formation which yielded the most numerous hominid fossils reflecting a long dry season and an open vegetation landscape

monitoring playa sedimentation using sequential radar images a series of ers 1 radar images of the chott el djerid playa in tunisia obtained at intervals of 35 days demonstrates the ability to monitor geological change from space the c band radar backscatter is shown from field measurements to be sensitive to changes in surface roughness at millimetric scale due to evaporative growth of halite and gypsum crystals backscatter increases gradually during the dry summer months and decreases rapidly in early winter as the rains begin episodic hydrogeological and sedimentological events including lake development channel flow and aeolian deposition can also be detected in addition to the seasonal pattern multitemporal spaceborne radar offers the prospect of being able to map the dynamics of evaporite sedimentation in continental playas