glacier subsurface heat flux characterizations for energy balance modelling in the donjek range southwest yukon canada we apply a point scale energy balance model to a small polythermal glacier in the st elias mountains of canada in order to investigate the applicability and limitations of different treatments of the glacier surface temperature and subsurface heat flux these treatments range in complexity from a multilayer subsurface model that simulates snowpack evolution to the assumption of a constant glacier surface temperature equal to 0 c the most sophisticated model includes dry densification of the snowpack penetration of shortwave radiation into the subsurface internal melting refreezing of percolating meltwater and generation of slush layers measurements of subsurface temperature and surface lowering are used for model validation and highlight the importance of including subsurface penetration of shortwave radiation in the model using an iterative scheme to solve for the subsurface heat flux as the residual of the energy balance equation results in an overestimation of total ablation by 18 while the multilayer subsurface model underestimates ablation by 6 by comparison the 0 c surface assumption leads to an overestimation of ablation of 29 in this study where the mean annual air temperature is about 8 c

depositional facies of the miocene pliocene ogallala formation northwestern texas and eastern new mexico deposition of the basal fluvial sediments of the miocene pliocene ogallala formation in western texas and eastern new mexico was controlled by topography on the underlying erosional surface paleovalley fill facies consist of gravelly and sandy braided stream deposits interbedded with and overlain by eolian sediments deposited as sand sheets and loess uplands on the pre ogallala erosional surface are overlain primarily by similar eolian sediments calcic paleosols consisting mostly of glaebules and rhizoconcretions of caco sub 3 occur throughout the eolian facies massive to laminated and locally pisolitic brecciated and recemented pedogenic calcretes occur primarily near or at the top of the ogallala formation eolian facies preserve numerous superposed calcretes and calcic paleosols reflecting slow episodic aggradation on a savannah or grassland under arid to subhumid climatic conditions the change from fluvial to mostly eolian sedimentation probably resulted from diversion of streams that deposited fluvial sediments of the ogallala formation to form the pecos and canadian rivers source areas for eolian sediments may initially have been flood plains of ogallala braided streams and later the flood plains of the newly formed pecos and canadian rivers 38 references

evaluation of simple geochemical indicators of aeolian sand provenance late quaternary dune fields of north america revisited abstract dune fields of quaternary age occupy large areas of the world s arid and semiarid regions despite this there has been surprisingly little work done on understanding dune sediment provenance in part because many techniques are time consuming prone to operator error experimental highly specialized expensive or require sophisticated instrumentation provenance of dune sand using k rb and k ba values in k feldspar in aeolian sands of the arid and semiarid regions of north america is tested here results indicate that k rb and k ba can distinguish different river sands that are sediment sources for dunes and dune fields themselves have distinctive k rb and k ba compositions over the basin and range and great plains regions of north america the hypothesized sediment sources of dune fields are reviewed and assessed using k rb and k ba values in dune sands and in hypothesized source sediments in some cases the origins of dunes assessed in this manner are consistent with previous studies and in others dune fields are found to have a more complex origin than previously thought use of k rb and k ba for provenance studies is a robust method that is inexpensive rapid and highly reproducible it exploits one of the most common minerals found in dune sand k feldspar the method avoids the problem of using simple concentrations of key elements that may be subject to interpretative bias due to changes in mineralogical maturity of quaternary dune fields that occur over time

origin and evolution of lunettes on the high plains of texas and new mexico lunettes isolated dunes on the lee side of playa basins are common landforms on the southern high plains of northwest texas and eastern new mexico the dunes contain calcareous 15 40 caco3 sandy loam or loamy sand with minor amounts of sepiolite deposited 25 000 800014c yr b p and derived by deflation of lacustrine carbonate in the basins the dunes also contain low carbonate 0 15 caco3 sand or loamy sand that was deposited 25 000 15 000 yr b p and 8000 5000 yr b p and was derived by deflation that created the basins or deflated from sand deposited in the basins buried soils are common in the lunettes a bk profiles characterize soils formed in the calcareous sandy loam the sandy low carbonate sediments contain a bt profiles in the oldest sand of some dunes and a bw a bt or a btk in the early and middle holocene sand the dune stratigraphy combined with carbon isotope data derived from dated a horizons in lunettes suggests the following scenario for the southern high plains the lunettes began forming as low carbonate sand dunes in the late pleistocene as playa basins were formed or deepened by wind erosion the erosion repeatedly alternated with stability the environment probably was cool and dry but one or more cool and wet intervals 25 000 15 000 yr b p resulted in a rise in the water table and deposition of lacustrine carbonate in the deepest basins there may have been short departures toward warmer and probably toward drier conditions throughout this time episodically dry conditions 15 000 8 000 yr b p resulted in deflation of the carbonate and further dune construction by repeated accretion of calcareous sandy loam or loamy sand the low carbonate sand was deposited during widespread drought and deflation 8000 5000 yr b p the dunes have been largely stable in the late holocene

a 250 000 year record of lunette dune accumulation on the southern high plains usa and implications for past climates abstract a concentration of lake playa basins occurs on the southern high plains shp of northwest texas and eastern new mexico associated with these lake playas are lee side lunettes positioned on their southeast margins ranging in height from 1 5 to 10 m an osl dating program was applied to 30 samples from lunettes associated with large lakes and small playa basins samples were extracted from trenched dune sections or from deep cores earlier shp lunette investigations show depositional ages primarily in the late wisconsin and holocene this research extends the timing of lunette accretion to the middle pleistocene the earliest recorded deposition for these features the expanded chronology permitted investigation into dune morphology on nested lunettes built on contracting lake margins outer lunettes formed prior to inner dunes but simultaneous deposition occurred on downwind ridges as younger lee side dunes were constructed large lake lunettes were inactive during discreet shp pluvial episodes from early wisconsin to lgm conversely these lunettes accreted when climatic conditions promoted basin desiccation and aeolian deflation this suggests their mode of formation contrasts with lunette models recognized for other regions from post lgm to earliest holocene active lunette accretion occurred from 16 to 11 ka followed by a significant period of lunette construction during the mid holocene late holocene lunette deposition was interrupted by intervals of landscape stability lunette deposition between 1300s and 1700s corresponds with drought intervals recognized in tree ring records from adjacent regions recent lunette activity on the plateau is contemporary with the 1930 s dust bowl further insight into shp response to changing climatic conditions was given by comparing lunette depositional events with previous investigations on sedimentation intervals for draws lake playa basins and sand sheets

the surface accumulation and ablation of a coastal blue ice area near cap prudhomme terre adelie antarctica a record of accumulation and ablation from a network of 47 stakes at a coastal blue ice area in terre adelie antarctica is presented and analyzed the record covers early 2004 to early 2006 from 25 field surveys including some in austral winter the two years are very different with a virtually null surface mass balance during the 2004 winter but large accumulation during the 2005 winter a snow ice energy and mass balance model is used to reproduce the accumulation and ablation record a parameterization for snow erosion by wind is included input meteorology is from the european centre for medium range weather forecasts ecmwf analyses and forecasts corrected using 1 year of local meteorological observations from an automatic weather station model results agree reasonably well with the observations wind erosion is the largest contributor to ablation removing much of the precipitation sublimation and to a lesser extent melt runoff together account for 60 cm w e of ablation in 2 years mainly in summer although the record is short it confirms high interannual variability and thus high sensitivity to meteorology and climate monitoring and understanding the mass balance of such coastal blue ice areas may help monitor and detect climate change in the antarctic coastal regions

study of the snow melt freeze cycle using multi sensor data and snow modelling the melt cycle of snow is investigated by combining ground based microwave radiometric measurements with conventional and meteorological data and by using a hydrological snow model measurements at 2000 m a s l in the basin of the cor devole river in the eastern italian alps confirm the high sensitivity of microwave emission at 19 and 37 ghz to the snow melt freeze cycle while the brightness at 6 8 ghz is mostly related to underlying soil simulations of snowpack changes performed by means of hydrological and electromagnetic models driven with meteorological and snow data provide additional insight into these processes and contribute to the interpretation of the experimental data

a reexamination of late pleistocene boreal forest reconstructions for the southern high plains previous paleoecological research on the southern high plains resulted in development of a late quaternary chronology of pollen analytical episodes and the proposal that boreal forest existed in the region in the late pleistocene these interpretations are now considered untenable because 1 a number of the radiocarbon ages are questionable 2 there are serious problems of differential pollen preservation and reproducibility of the pollen data 3 there is an absence of supporting geological or paleontological data and 4 the soils of the area contain none of the distinctive pedological characteristics produced by a boreal forest available data suggest that the region was primarily an open grassland or grassland with some nonconiferous trees through most of the quaternary

analysis of snow in the 20th and 21st century geophysical fluid dynamics laboratory coupled climate model simulations 1 we evaluate the representation of the 20th century northern hemisphere north american and eurasian snow cover extent frequency and mass by the geophysical fluid dynamics laboratory coupled climate model version 2 cm2 and then explore the 21st century trends and changes in these quantities the cm2 simulations of 20th century climate capture the seasonal cycle in northern hemisphere snow cover extent and produce a mean annual snow area of 25 106 km2 that equals the satellite based observations for the period 1973 2000 the simulated snow cover frequency and snow mass generally decline from north to south but longitudinal gradients in these variables are also found snow mass over north america especially during spring is underestimated by cm2 simulations of 21st century climate using three intergovernmental panel on climate change special report on emission scenarios reveal strong trends in northern hemisphere snow cover extent frequency and mass these simulations suggest that the annual northern hemisphere mean snow cover extent total snow mass will decrease by 12 to 26 20 to 40 by 2100 from their 21st century mean values large declines in 21st century snow cover frequency up to 50 and snow mass up to 100 kg m 2 arise during fall winter and spring over southern canada and the northern united states the western cordillera of north america and western eurasia compared to the 20th century cm2 simulations

optical dating of geoarchaeologically significant sites from the southern high plains and south texas usa the southern high plains of the united states is a key region for the investigation of early human occupation of north america this area including selected archaeological sites located in southern texas contains a range of aeolian fluvial and playa deposits such deposits may be suited to luminescence based methods of age assessment in this paper we describe a combination of multiple and single aliquot optical dating results for a selection of sites with some independent age control we find generally good agreement between multiple and single aliquot equivalent dose de estimates for the 20 samples compared but note that the single aliquot approach results in errors in mean de s to be less by an order of magnitude our results suggest that at least some of the single aliquot methods are of great utility for low latitude geoarchaeological sites

new data on the stratigraphy and pedology of the clovis and plainview sites southern high plains abstract the well known clovis and plainview archaeological sites of new mexico and texas have yielded new data on regional late quaternary geologic paleoclimatic and pedologic histories eolian sedimentation at the clovis site from about 10 000 to less than 8500 yr b p was followed by the formation of a cumulic soil between 8500 and 5000 yr b p episodic eolian and slope wash deposition then culminated in massive eolian sedimentation about 5000 yr b p after which a haplustalf formed then was subsequently buried by part of a dune system within the last 1000 yr at the plainview site a basal stream gravel contains plainview cultural material ca 10 000 yr b p which is followed by a localized early holocene lacustrine deposit two eolian deposits the younger dating to about 5000 yr b p and a marsh deposit which slowly accreted as an argiustoll formed in the younger eolian unit the data indicate that on the southern high plains 1 between 12 000 and 8500 yr b p sedimentation varied from site to site 2 there was a regional climate change toward warming and drying in the early holocene 3 two episodes of severe drought apparently occurred in the middle holocene 6500 to 4500 yr b p 4 between 4500 yr b p and the present an essentially modern climate existed but with several shifts toward aridity within the last 1000 yr 5 argillic horizons have developed in late holocene soils 6 clay illuviation can occur in calcareous soils and 7 long distance correlation of holocene stratigraphy in the region is possible particularly with the aid of soil morphology

a distributed temperature index ice and snowmelt model including potential direct solar radiation hourly melt and discharge of storglaciaren a small glacier in sweden were computed for two melt seasons applying temperature index methods to a 30 m resolution grid for the melt component the classical degree day method yielded a good simulation of the seasonal patient of discharge but the pronounced melt induced daily discharge cycles were not captured modelled degree day factors calculated for every hour and each gridcell from melt obtained from a distributed energy balance model varied substantially both diurnally and spatially a new distributed temperature index model is suggested attempting to capture both the pronounced diurnal melt cycles and the spatial variations in melt due to the effects of surrounding topography this is accomplished by including a radiation index in terms of potential clear sky direct solar radiation and thus without the need for other data besides air temperature this approach improved considerably the simulation of diurnal discharge fluctuations and yielded a more realistic spatial distribution of melt rates the incorporation of measured global radiation to account for the reduction in direct solar radiation due to cloudiness did not lead to additional improvement in model performance

comparison between the results of a snow metamorphism model and remote sensing derived snow parameters in the alps abstract the numerical snow metamorphism model crocus derives a complete description of the snow cover according to its geographical location range elevation slope and orientation from the remote sensing data snow parameters that were comparable to the model results were derived the lower elevation of the snow cover the surface grain size and the surface temperature the landsat thematic mapper sensor was used because it has a good spatial resolution a short wave infrared channel which is sensitive to grain size and a thermal infrared channel a first landsat tm thematic mapper scene was acquired on 24 april 1992 and a second one on 11 december 1992 a dem digital elevation model was used to obtain the local incidence angles and the elevation of each snow pixel the pixels were then grouped according to the crocus classification range elevation slope orientation and the mean snow characteristics for each class were compared with the crocus results the lower limit of snow and the surface grain size derived from tm data compared favorably with the model results even if those parameters were not always easy to define larger differences were found for the temperature because it varies rapidly and is very sensitive to shadowing by surrounding mountains and also because its remote measurement is dependent on atmospheric conditions

non linear connections between dune activity and climate in the high plains kansas and oklahoma usa discrete dune fields are found throughout much of the great plains of north america and the timing of past dune activity is often used as a proxy for paleoclimate because of the intuitive link between dune activity and a more arid climate this research suggests that feedbacks in the soil geomorphic system create a relationship between dune activity and climate that varies both spatially and temporally older eolian landforms are more resistant to activation because of the long term accumulation of finer soil particles in a bt horizon which retain moisture and anchor the deposit even during more arid times conversely younger deposits lack these fines and are more easily reactivated this spatially variable relationship is supported by soil stratigraphy particle size analysis and optical age control additionally the water retention of the bt horizons is quantifiably greater than that of the soils found in the younger dunes of the area this complication in the relationship between eolian activity and climate is important because it suggests that caution is needed when using past dune activity as the lone proxy for paleoclimate

simulation of snow shielding corrections for cosmogenic nuclide surface exposure studies abstract snow cover reduces cosmogenic nuclide production rates in bedrock corrections for snow cover can be more than 10 in mountainous mid latitude regions where many glacial chronologies have been constructed using cosmogenic nuclide surface dating of landforms most published snow corrections use historic climate data of limited duration that are not likely to reflect adequately the full range of snow conditions over the time of exposure we present a model for describing the impact of snow burial on long term exposure histories of landforms the model applies an energy balance approach to snowpack evolution and incorporates both historic and long term climate proxy data attenuation of cosmogenic fast neutrons is modeled alternatively as a simple exponential decrease with increased shielding or as a thin surface layer with constant production followed by an exponential decrease with increasing depth the choice of attenuation model has little effect on the modeled results for the cairngorms but will have a more significant effect in regions characterized by thinner less dense snowpacks spatial variability in snow cover is modeled as a function of elevation only ignoring local variability in snow accumulation as a result of slope aspect wind redistribution and local topography thus model results reveal general spatial and temporal trends in snow shielding effects rather than site specific corrections applications to data from the cairngorm mountains of scotland show that the constant plus exponential cpe production rate depth profile reduces but does not eliminate snow shielding effects under present day conditions snow at 900 m in the cairngorm mountains reduces average production rates by 6 using the cpe profile and 9 with the exponential profile ep long term climate simulations from 15 5 ka through today produce larger snow shielding effects mainly because they predict an increased proportion of precipitation as snowfall during the younger dryas at 900 m this long term simulation reduces average cosmogenic isotope production rates by 12 cpe and 14 ep these results indicate that snow shielding corrections based on historic climate records may be a potential source of systematic error in midlatitude mountainous regions

mass balance model parameter transferability on a tropical glacier we explore the small scale spatial and temporal transferability of model parameters between two points in the ablation zone of tropical glaciar shallap cordillera blanca peru 9 s 77 w 4800 m a s l in order to provide a robust assessment of the performance of a process based glacier mass balance model relative surface height change is calculated at hourly time steps and cumulative values are compared to surface height measurements made at irregular intervals 14 64 days over the course of two continuous hydrological years august 2006 august 2008 best performing parameter combinations were determined for each point from the outcome of 1000 model simulations for which parameters were varied randomly within a defined range with these parameter combinations measurements for a specific location and time span are well reproduced transferring the parameter combination as optimized for one location to the other location in the ablation zone increases the errors of modeled cumulative mass balance by 5 1326 mm ice eq a 1 transferring the parameter combinations as optimized for one year to the other year increases the modeled errors in cumulative mass balance by 18 3179 mm ice eq a 1 model errors generally increase during periods with frequent snowfall and snow cover this could reflect either the inherent difficulty of modeling complex snow processes or the inability of the model to correctly capture the pattern of albedo evolution at this site the magnitude of errors associated with parameter transfer in space and time highlights the need for improving model performance for robust climatological and or hydrological analyses on tropical glaciers

changes in the heterogeneity of mesoscale distribution patterns of larval fish associated with a shallow coastal haline front abstract in june 1983 there was a large outflow of inland fresh waters from the rhone river that covered a broad area off the northern coast of catalonia northwestern mediterranean giving rise to a surface plume of fresh water with a distinct haline front at its southern edge this hydrodynamic event brought about substantial changes in the structure of the larval fish community in the area which was in turn reflected in an increase in spatial heterogeneity large numbers of species and individuals were found along the southern edge of the plume in association with the haline front whereas with the exception of certain species larval fish concentrations in the area covered by the plume tended to be considerably lower than in the rest of the area species predominantly located in the surface water layers were probably transported by the plume out to the plume s edge other species which apparently enjoy a broader vertical distribution range were less affected by the surface advection processes

dependence of the water retention curve of snow on snow characteristics the water retention curve wrc which shows the relationship between the volumetric liquid water content v and suction h is a fundamental part of the characterization of hydraulic properties therefore the formulation of the wrc as a function of snow characteristics is essential for establishing a model of water movement through the snow cover in this study we measured the wrc of several snow samples which had different characteristics grain size bulk dry density and grain type using a gravity drainage column experiment and then analysed these data using the van genuchten soil physics model vg model the shape of the wrc depended strongly on both the sample grain size d and bulk dry density p therefore we introduced the parameter d to model the wrc of snow the relationships between the parameters and n of the vg model and d change with grain type for melt forms a which is related to the inverse value of the air entry suction increases quickly as d decreases whereas n which is related to the gradient of v vs h increases with d conversely neither of these parameters of the vg model for rounded grains showed obvious dependence on d these results suggest that water movement through snow cover can be modelled using grain size bulk dry density and grain type based on the soil physics model

soil forming intervals caused by eolian sediment pulses in the lahontan basin northwestern nevada we have studied a series of toyeh post isotope stage 2 eolian dust fall was the source of fines and salts in these soils apparently this influx was concentrated during two brief intervals or pulses one during the holocene and one during the previous isotope stage 5 interpluvial leaching during the sehoo pluvial removed salts from churchill soils carbonate and soluble salts now observed in the churchill soils represent a toyeh overprint on the churchill profile these pulses of fine sediment and accompanying salts are tantamount to the soil forming intervals that morrison described in the lahontan area episodic eolian dustfall provides fine particles of silicates calcite and soluble salts that infiltrate into the clast supported alluvial piedmont sediments several hundred playas exist in the basin and range each providing directional dust contributions that influence local and regional soil development we counsel caution in assuming constant gradual development of soil properties without due consideration of paleoenvironmental influences on soil forming factors

mt blanco revisited soil geomorphic implications for the ages of the upper cenozoic blanco and blackwater draw formations mt blanco on the eastern edge of the southern high plains of texas contains stratigraphic features significant in interpreting the late cenozoic history of the region and the vertebrate paleontology of the great plains however the stratigraphic relations are confused in the literature or are unreported mt blanco is the type locality for the blanco formation and the blanco local fauna which occurs throughout north america and is the type fauna for the blancan land mammal age in north america here also occur exposures of the blackwater draw formation an extensive 120 000 km sup 2 eolian sheet that is the surficial cover of the region and contains the 1 4 ma guaje ash and several buried soils a reexamination of the section shows that 1 the blackwater draw formation an eolian deposit contains three well expressed buried soils 5 yr hues argillic horizons greater than or equal to 1 m thick stages iii and iv calcic horizons and the similar regional surface soil paleustalf 2 the guaje ash is within the lower blackwater draw formation but is separated from the blanco formation a lacustrine unit by about 1 m of sediment including the lowest buried soil and 3 the lowest buried soil showsmore a stage iv calcrete formed at the top of the blanco formation and the base of the blackwater draw formation and probably took about 200 ka to form these new data suggested that deposition of the type blanco sediments may have ended by about 1 6 ma or earlier since that time the blackwater draw formation has accumulated episodically periods of nondeposition are characterized by landscape stability and pedogenesis less

use of a multilayer snow model to assess grazing conditions for reindeer high density snow layers deteriorate grazing conditions for reindeer during winter we compare two different methods for identifying past winters with difficult grazing conditions for reindeer in kautokeino northern norway a long term climate analysis based on monthly values of precipitation and temperature 1900 2011 demonstrated that the reported winters were difficult to identify systematically the processes leading to hard layers or ground ice layers occur on daily not monthly timescales and whether or not specific conditions are problematic depends on the development throughout the winter not just on single values to better analyse the weather conditions and development over time that favour the formation of high density snow layers we apply the multilayer model snowpack over the period 1956 2010 we simulate the evolution of the snowpack by forcing the model with 6 hour interval meteorological data the model output was analysed by summing up the vertical extent of the simulated high density snow layers 350 kg m 3 for each winter these results were compared with historical records of difficult winter grazing conditions reported in the period 1956 2010 in particular the heavy losses of reindeer during the catastrophic 1967 68 winter were caused by the occurrence of ground ice together with long snow cover duration this unfavourable coincidence is well reproduced by our model results together with eight of the ten reported difficult winters

a computer based system simulating snowpack structures as a tool for regional avalanche forecasting this paper describes the current state of a complete automatic system of three numerical models that simulate snow cover stratigraphy and avalanche risks for operational avalanche forecasting the first model safran estimates relevant meteorological parameters affecting snowpack evolution the second crocus is a snow numerical model which simulates the physical processes inside the snowpack and its stratigraphy the last model mepra is an expert system based on an assessment of snowpack stability it deduces natural and accidental avalanche risks to describe the great variability of the snowpack and the associated avalanche risks this automatic system simulates snow cover evolution and its stability for many typical slopes elevations and aspects representative of the different french massifs to achieve this result different kinds of validations have been carried out since winter 1981 they are mainly based on comparisons with different sets of measurements and on the opinion of users although the routinely obtained results do not yet take into account all small scale effects such as wind transport they have been considered as valuable information by avalanche forecasters since 1992 93 and used operationally since then

eolian sedimentation and soil development on a semiarid to subhumid grassland tertiary ogallala and quaternary blackwater draw formations texas and new mexico high plains abstract eolian sediments have accumulated as non glacigenic loess and thin sand sheets on the central and southern high plains grasslands of texas and new mexico since the late miocene locally as much as 110 m of eolian sediments with numerous paleosols are preserved in the quaternary blackwater draw formation and the upper part of the miocene pliocene ogallala formation these sediments and paleosols which cover more than 130 000 km2 are similar to recent surface sediments and soils and record a long period of episodic eolian transport and sedimentation and pedogenesis on a stable low relief grass covered landscape eolian sections which comprise the fine sand to coarse silt lithofacies of the ogallala formation and the very fine to fine sand and sandy mud lithofacies of the blackwater draw formation generally lack primary sedimentary structures grain size of ogallala sediments decreases from west to east and grain size of blackwater draw sediments decreases from southwest to northeast soil horizonation is well developed in most sections and buried calcic and argillic horizons are common calcic horizons are characterized by sharply increased caco3 content in the form of filaments nodules and petrocalcic horizons calcretes argillic horizons are characterized by increased illuvial clay pedogenic structure and darker reddish hues rhizocretions are common locally open root tubules which are typically less than 1 mm in diameter and characteristic of small plants like grasses are present in all ogallala and blackwater draw eolian sediments paleosols preserved in eolian sediments of the high plains reflect periods of sedimentation followed by episodes of landscape stability and pedogenesis and negligible sedimentation episodes of sedimentation and soil development likely resulted from cyclic decreases and increases in available moisture and vegetative cover eolian sediments were eroded and transported eastward during dry periods when vegetation was sparse in source areas such as the western high plains and the pecos valley during humid periods more abundant vegetation probably protected source areas from deflation and resulted in landscape stability across the high plains

record of pre late wisconsin giant floods in the channeled scabland interpreted from loess deposits loess deposits adjacent to flood coulees on the columbia plateau in eastern washington state record multiple episodes of pre late wisconsin cataclysmic floods evidence in the loess consists of flood cut unconformities upward fining in individual loess strata and flood deposits that consist of basaltic gravel fragments of calcified paleosols and slackwater sediment at least six episodes of floods during the pleistocene are indicated by paleomagnetic measurements tephra correlations and the stratigraphic position of flood indicators one episode of the six occurred prior to 790 ka the most recent episode before the last glacial floods occurred at 36 ka at the latest

stratigraphy and geochronology of upper quaternary eolian sand on the southern high plains of texas and new mexico united states eolian sand in dune fields and sand sheets cover 10 000 km 2 10 of the southern high plains of northwestern texas and eastern new mexico these deposits are concentrated in three west east trending belts of dunes the muleshoe lea yoakum and andrews dune fields from north to south that appear to be eastern extensions of the mescalero monahans dune system in the pecos river valley and in the seminole sand sheet a discontinuous accumulation of sheet sands between the lea yoakum and monahans andrews dunes the most common landforms are parabolic dunes associated with blowouts coppice dunes and sand sheets all typical of sandy vegetated semiarid landscapes barchan dunes in keeping with a relatively limited sand supply and an underlying surface that is relatively hard blackwater draw formation pleistocene and fence row dunes historic dunes formed along field boundaries these eolian deposits accumulated episodically in the late pleistocene and holocene and provide clues to the history of regional drought and aridity the earliest phase of sedimentation occurred when sheet sands were deposited between 11 000 and 8000 14 c yr b p probably in several phases based on archaeological data as a result of episodic drought beginning between 11 000 and 10 000 yr b p eolian deposits dating between 8000 and 3000 yr b p are rare although eolian sediment 8000 4500 14 c yr b p is ubiquitous in the draws that cross the region and paleoenvironmental indicators show that the region was subjected to aridity throughout middle holocene time the middle holocene deposits most likely were remobilized in late holocene time most of the deposits and landforms of the dune fields and sand sheets are late holocene dating before 4000 14 c yr b p and mostly before 1500 14 c yr b p the muleshoe and lea yoakum dunes and the seminole sand sheet underwent substantial eastward expansion in late holocene time buried soils and radiocarbon ages show that the eolian sand accumulated in several stages probably in response to cyclic drought the muleshoe dunes accumulated after ca 1300 cal yr b p ca 1400 14 c yr b p after ca 750 670 cal yr b p ca 850 750 14 c yr b p just after ca 500 cal yr b p ca 450 14 c yr b p and during the nineteenth and twentieth centuries the lea yoakum dunes were active after ca 3400 cal yr b p ca 3200 14 c yr b p and historically the seminole sand sheet was active ca 430 330 cal yr b p ca 360 14 c yr b p and in the twentieth century the andrews dunes were subjected to at least two phases of eolian sedimentation after ca 2320 cal yr b p ca 2320 14 c yr b p comparisons with eolian chronologies from other regions on the great plains suggest that dune mobilization was a regional phenomenon after ca 2300 cal yr b p ca 2300 14 c yr b p after ca 1500 1400 cal yr b p ca 1650 1550 14 c yr b p after ca 700 cal yr b p ca 800 14 c yr b p between 500 and 300 cal yr b p ca 450 300 14 c yr b p and in the nineteenth century the climatic fluctuations responsible for mobilizing the dunes probably were relatively minor yet the landscape impacts were substantial resulting in widespread wind erosion and dune construction

the fate of river discharge on the continental shelf 2 transport of coastal low salinity waters under realistic wind and tidal forcing a three dimensional numerical simulation of shelf circulation is presented we employ realistic forcing for the southeast u s continental shelf during the spring season we show that the strongest offshore transport of river induced coastal low salinity waters and associated materials occurs near the surface the preferred mean pathway is in the northeastward direction and it takes about 2 months to cross the entire shelf owing to the mean direction of surface transport and the topography of the south atlantic bight shelf the preferred location for springtime removal is off charleston south carolina and presumably in the vicinity of the charleston bump the transport and fate of the river induced coastal low salinity waters during the spring season are determined by 1 the stratification of nearshore waters which is due to the high river runoff and causes the decoupling between near surface and near bottom layers 2 the prevailing northeastward winds which cause significant offshore transport within the shallow near surface ekman layer and 3 the tidally induced bottom stirring m2 tides comparison of model and data time series of currents shows very good agreement standard deviations of the model and data computed empirical orthogonal functions are almost identical while the respective variance conserving spectra agree both in amplitude and phase

complex pedogenesis related to differential aeolian sedimentation in microenvironments of the southern part of the semiarid region of argentina abstract the aim of this paper is to explain soil genesis and spatial variability in the soil cover of a flat landscape in the southern part of argentina s semiarid region soil survey data indicate random differences in the properties of soils lying within a few hundred meters of one another as reflected in an intricate distribution pattern which cannot be explained by the climatic theory of soil genesis in a single pedogenetic cycle this pattern is unrelated to the actual vegetation cover the soil parent materials consist of a

validation of the energy budget of an alpine snowpack simulated by several snow models snowmip project many snow models have been developed for various applications such as hydrology global atmospheric circulation models and avalanche forecasting the degree of complexity of these models is highly variable ranging from simple index methods to multi layer models that simulate snow cover stratigraphy and texture in the framework of the snow model intercomparison project snowmip 23 models were compared using observed meteorological parameters from two mountainous alpine sites the analysis here focuses on validation of snow energy budget simulations albedo and snow surface tem perature observations allow identification of the more realistic simulations and quantifi cation of errors for two components of the energy budget the net short and longwave radiation in particular the different albedo parameterizations are evaluated for different snowpack states in winter and spring analysis of results during the melting period allows an investigation of the different ways of partitioning the energy fluxes and reveals the complex feedbacks which occur when simulating the snow energy budget particular attention is paid to the impact of model complexity on the energy budget components the model complexity has a major role for the net longwave radiation calculation whereas the albedo parameterization is the most significant factor explaining the accu racy of the net shortwave radiation simulation

effects of coastal transport on larval patches models and observations abstract we used a combination of field observations and numerical modeling to examine the physical mechanisms responsible for the evolution and transport of patches of blue crab larvae in the mouth of delaware bay the observations consisted of larval collections and surface salinity measurements taken along a moving spatial grid whose origin was determined by a satellite tracked drifter examination of field observations revealed a slender larval patch that was aligned with salinity contours measurement of the salting rate of the larval patch indicated that the patch moved through the offshore edge of a buoyant plume due to wind driven upwelling circulation a numerical model that provided realistic simulations of the flow field at the mouth of delaware bay and the adjoining coastal ocean was used to examine the physical mechanisms responsible for the movement and evolution of the patch we conducted a series of simulations in which we separately examined the effects of tides buoyancy driven flow and wind driven transport results showed that both tides and buoyancy driven flow tend to elongate an initially square fluid element although winds alone have little effect on the shape of a patch wind driven flow can effectively move a patch through a complex flow field in which the deformation by tides and buoyancy driven circulation can have significant effects this study represents the first observation and analysis of a larval patch that remains intact while moving through the edge of a buoyant plume it provides new insight into the shape of larval patches in delaware bay and any region with strong buoyancy and tidally driven flow suggesting that typical larval patches may not be characterized by equal across and alongshelf dimensions but instead tend to be slender shapes that are aligned with the flow field

middle holocene drought on the southern high plains abstract the climate of the southern high plains during the middle holocene is indicated by data from a variety of sources stratigraphic geomorphic and pedologic research at six localities in draws several dune sites and one playa lake basin show that widespread eolian erosion and sedimentation began in some areas by 9000 yr b p and culminated 6000 4500 yr b p probably because of warmer drier conditions that reduced the vegetative cover archaeological investigations at three sites provide evidence for the excavation of wells at this time apparently because of a declining water table studies of a few vertebrate and invertebrate faunas also indicate warming and drying in the middle holocene climate models and very limited isotopic data from bison bone suggest that summers in the middle holocene were warmer than present with reduced effective precipitation all lines of evidence indicate that the southern high plains was subjected to prolonged drought in the middle holocene with a maximum between 6500 and 4500 yr b p conforming climatically and chronologically to the altithermal

two dimensional numerical modelling of surface wind velocity and associated snowdrift effects over complex mountainous topography a new experimental software for blowing snow sytron2 is pre sented it takes advantage of the previous limited realization sytron1andof the entire real time operational environment of the automatic chain safran crocus mepra scm it runs presently on a rectangular grid with a mesh size of about 45m covering an area of 3 0 3 0km 2 around the observation test site col du lac blanc french alps 2700m a s l near the alpe d huez ski resort sytron2 is initialized with a realistic snowpack representation derived fromthe scmoutputs andcoupledto awind fieldcom puted by the new samver model the final aim is to build a fully embedded tool sui table for representing snowdrift effects with a better resolution at different specific locations the different tools and operators used are described as well as the field valida tion processes which are based on remote identification of the eroded and accumulated areas using digital pictures

chronology and geochemistry of late holocene eolian deposits in the brandon sand hills manitoba canada abstract accelerator mass spectrometry and conventional radiocarbon age determinations of organic matter from paleosols indicate that the brandon sand hills area of southern manitoba has been subjected to recurrent intervals of eolian activity in the past 5000 years although precise regional correlations are precluded by dating uncertainties periods of most notable paleosol development occurred around 2300 to 2000 1400 to 1000 and 600 to 500 cal yr bp with eolian activity occurring before and after each of these periods episodes of eolian activity may correspond to periods of regional drought whereas paleosols mark periods of increased moisture availability and stabilization by vegetation the geochemistry of the eolian sands paleosols and source sediments indicates that partial leaching of carbonates occurs from pedogenesis during humid climatic phases and that this is probably the primary mechanism of carbonate depletion of eolian sands in this area recent trends in sand dune activity from historic aerial photography and early explorers accounts indicate that the few active dunes that presently exist have stabilized at a rate of 10 20 per decade despite several severe droughts in the 20th century this may be attributed to pre settlement droughts that were more severe than those in historic times although regional dune stabilization may also be related in part to the spread of forest cover in the past few hundred years

characterizing biases in mountain snow accumulation from global data sets author s wrzesien melissa l pavelsky tamlin m durand michael t dozier jeff lundquist jessica d

modeling time series of microwave brightness temperature in antarctica this paper aims to interpret the temporal variations of microwave brightness temperature at 19 and 37 ghz and at vertical and horizontal polarizations in antarctica using a physically based snow dynamic and emission model sdem sdem predicts time series of top of atmosphere brightness temperature from widely available surface meteorological data era 40 re analysis to do so it successively computes the heat flux incoming the snowpack the snow temperature profile the microwaves emitted by the snow and finally the propagation of the microwaves through the atmosphere up to the satellite since the model contains several parameters whose value is variable and uncertain across the continent the parameter values are optimized for every 50 km 50 km pixel simulation results show that the model is inadequate in the melt zone where surface melting occurs on at least a few days a year because the snowpack structure and its temporal variations are too complex in contrast the accuracy is reasonably good in the dry zone and varies between 2 and 4 k depending on the frequency and polarization of observations and on the location at the antarctic scale the error is larger where wind is usually stronger suggesting either that meteorological data are less accurate in windy regions or that some neglected processes e g windpumping surface scouring are important at dome c in calm conditions a detailed analysis shows that most of the error is due to inaccuracy of the era 40 air temperature 2 k finally the paper discusses the values of the optimized parameters and their spatial variations across the antarctic

soil geomorphology the linkage of pedology and surficial processes geologists have made significant contributions to the discipline of pedology however until recently direct contributions came largely prior to 1935 as exemplified by those of powell and shaler during the late 19th century tandarich et al 1987 during much of the twentieth century geology and pedology have generally evolved along nearly separate pathways re integration of the two disciplines began slowly in the late 1950s and early to middle 1960s through the research and publications of ruhe 1956 1960 1964 richmond 1962 and morrison 1964 1965 1967 richmond s and morrison s research has provided much of the basis for the use of soils in the study of the stratigraphy of quaternary deposits in the western u s a birkeland 1984 the soil stratigraphic unit the geosol is a key component of the methodology developed by morrison geosols are presumed to have formed only during soil forming intervals interglacial or interstadial periods when climatic conditions were deemed optimal for rapid soil development recognition of soil stratigraphic units as geosols automatically conferred climatic as well as stratigraphic significance to buried soils this approach may have great utility in regions at higher latitudes that were characterized by extremes of climatic fluctuation during the qua ternary catt 1986 with little or no soil development during cold climate intervals a rather different approach involving the use of soils has been adopted by geoscientists conducting geomorphological research during the mid to late 1960s studies by researchers such as balster daniels hawley gile parsons and yaalon focussed on the nature of the relationships linking soils and landscape elements in many respects the philisophical approach to soil geomorphic research emphasized in the studies of these scientists strongly reflected the intellectual impact of jenny 1941 on the science of pedology this philosophy also strongly influenced the research of birkeland and following publication of birkeland s important textbook pedology weathering and geomorphological research 1974 a dramatic increase in the use of pedology in the geosciences occurred as researchers focussed on the study of landscape evolution in our view this emerging marriage of pedology and studies of surficial processes provides a critical framework for both the study of soil genesis and the study of evolution of and or stability of landscape elements

flow induced aggregation of plankton at a front a 2 d eulerian model study abstract we use a simple 2 d eulerian numerical model to illustrate a mechanism whereby depth keeping swimming behavior on the part of an organism combined with a convergent flow field at a surface front can create dense populations in this model a steady flow field and vertical diffusivity are prescribed along with an initial plankton distribution the plankton swim vertically with speeds that depend only on depth where the form of that dependence may reflect such factors as the vertical variation in light level or the concentration of some prey organism the eulerian nature of the model enables diffusion to be treated explicitly the numerical model describes the evolution of an initial plankton patch in time a parameter study illustrates the roles played by diffusion water velocity and details of the animals swimming behavior on patch evolution output from the model is compared with data taken at a dense plankton patch observed near a small scale front in the northern great south channel in early june 1989

vertebrate bearing eolian unit from the ogallala group miocene in northwestern texas the upper couch formation is part of the lower of two formations composing the ogallala group in blanco and yellowhouse canyons in northwestern texas an eolian origin for the upper couch formation is indicated by its mean grain size pedogenic carbonate nodules massive bedding and blanketlike morphology the unit conforms poorly to the usual eolian depositional models it resulted from a combination of the processes involved in loess and sand sheet formation grassland or savanna vegetation probably existed over the area and aided in sediment trapping vertebrates are unusual in eolian units but the adaptations and mode of preservation of those in the upper couch formation also support an eolian interpretation this and other widespread silty sand sheets in the ogallala indicate major fluctuations in depositional style possibly climatically controlled lateral continuity and preservation of vertebrates give silty sand sheets great potential as correlation tools

surface mass balance of glaciers in the french alps distributed modeling and sensitivity to climate change a new physically based distributed surface mass balance model is presented for alpine glaciers based on the crocus prognostic snow model it resolves both the temporal 1 hour time step and spatial 200 m grid step variability of the energy and mass balance of glaciers mass balance reconstructions for the period 1981 2004 are produced using meteorological reconstruction from the safran meteorological model for glacier de saint sorlin and glacier d argentiere french alps both glaciers lost mass at an accelerated rate in the last 23 years the spatial distribution of precipitation within the model grid is adjusted using field mass balance measurements this is the only correction made to the safran meteorological input to the glacier model which also includes surface atmospheric temperature moisture wind and all components of downward radiation independent data from satellite imagery and geodetic measurements are used for model validation with this model glacier sensitivity to climate change can be separately evaluated with respect to a full range of meteorological parameters whereas simpler models such as degree day models only account for temperature and precipitation we provide results for both mass balance and equilibrium line altitude ela using a generic alpine glacier the sensitivity of the ela to air temperature alone is found to be 125 m c 1 or 160 m c 1 if concurrent stefan boltzmann longwave radiation change is taken into account

archaeological geology of the lubbock lake site southern high plains of texas the lubbock lake site is a well stratified archaeological locality in yellowhouse draw on the southern high plains of texas it has a cultural record that spans the past 11 000 yr that is contained within a thick sequence of sediments and soils the sequence at lubbock lake is one of the most closely integrated records of late quaternary human occupation sedimentation and soil formation documented in north america stratum 1 11000 yr b p and older was deposited by a meandering stream and contains clovis age cultural remains stratum 2 is composed of lacustrine sediments 11000 to 10000 yr b p and overlying marsh deposits 10000 to 8500 yr b p with paleoindian material in both units the firstview soil 8500 to 6300 yr b p formed in the top of stratum 2 stratum 3 6300 to 5000 yr b p contains early archaic material eolian and marsh deposits suggestive of warm arid conditions and the yellowhouse soil indicating a brief period of landscape stability stratum 4 5000 to 4500 yr b p is primarily an eolian unit that marks the second of two periods of severe drought in the middle holocene the lubbock lake soil formed in stratum 4 beginning 4500 yr b p coincides with the late archaic and ceramic periods and documents landscape stability and a return to climatic conditions similar to those of today stratum 5 contains late ceramic protohistoric and historic archaeological material within eolian and slopewash sediments and the apache and singer soils which indicate several shifts toward aridity within the past 1 000 yr

a new snow svat to simulate the accumulation and ablation of seasonal snow cover beneath a forest canopy a new snow soil vegetation atmosphere transfer snow svat scheme which simulates the accumulation and ablation of the snow cover beneath a forest canopy is presented the model was formulated by coupling a canopy optical and thermal radiation model to a physically based multi layer snow model this canopy radiation model is physically based yet requires few parameters so can be used when extensive in situ field measurements are not available other forest effects such as the reduction of wind speed interception of snow on the canopy and the deposition of litter were incorporated within this combined model snowcan which was tested with data taken as part of the boreal ecosystem atmosphere study boreas international collaborative experiment snow depths beneath four different canopy types and at an open site were simulated agreement between observed and simulated snow depths was generally good with correlation coefficients ranging between r 2 0 94 and r 2 0 98 for all sites where automatic measurements were available however the simulated date of total snowpack ablation generally occurred later than the observed date a comparison between simulated solar radiation and limited measurements of sub canopy radiation at one site indicates that the model simulates the sub canopy downwelling solar radiation early in the season to within measurement uncertainty

origin of late quaternary dune fields on the southern high plains of texas and new mexico mostly stabilized late holocene eolian sands on the southern high plains of the united states were studied to determine their origins and to assess whether present dune stability depends more strongly on sediment supply sediment availability or transport limitations geomorphic sedimentological and geochemical trends indicate that late holocene dunes formed under westerly paleowinds broadly similar to those of today mineralogical and geochemical data indicate that the most likely source for the sands is not the pecos river valley but the pleistocene blackwater draw formation an older extensive eolian deposit in the region these observations suggest that new sand is supplied whenever vegetation cover is diminished to the extent that the blackwater draw formation can be eroded in agreement with modern observations of wind erosion in the region we conclude therefore that southern high plains dunes are stabilized primarily due to a vegetation cover the dunes are thus sediment availability limited this conclusion is consistent with the observation that in the warmest driest part of the region where vegetation cover is minimal dunes are currently active over a large area geochemical data indicate that southern high plains dunes are the most mineralogically mature quartz rich sands yet studied in the great plains which suggests a long history of eolian activity either in the dune fields or during deposition of the blackwater draw formation

miocene marine nonmarine correlations atlantic and gulf coastal plains north america abstract a survey of the records of the remains of miocene land mammals from nearshore marine deposits on the atlantic and gulf coastal plains of the united states reveals a number of occurrences where the relationship between mammalian and invertebrate biochronologies can be directly compared vertebrate paleontologists have constructed and calibrated a time scale of geochrons north american mammal ages and informal subages based on the occurrence of certain mammalian genera this scale can be compared directly with neritic molluscan diatom and foraminiferal biostratigraphies that in turn can be calibrated with the neogene planktonic foraminiferal zones in the warm water provinces surrounding southeastern north america such cross correlations allow the tracing of geochrons from the land to sea as well as across facies boundaries within these major environments the demonstration of the wider utility of the mammalian time scale in correlation and the testing of correlations proposed by other disciplines is an important conclusion from this study

epeirogenic controls on canadian river incision and landscape evolution great plains of northeastern new mexico abstract the canadian river has carved a deep bedrock canyon into the great plains of northeastern new mexico in response to a complex interaction of post laramide epeirogenic rock uplift processes along the jemez lineament and downstream baselevel fall caused by late tertiary and quaternary evaporite dissolution broad slow bulging along the jemez lineament a lithospheric scale structure with prolific late cenozoic volcanism along its trend helps drive incision in the canyon canadian river canyon fluvial terraces mapped and correlated according to soils elevation and rock type criteria reveal longitudinal profiles that appear broadly warped across the jemez lineament and converge to the modern channel profile both upstream and downstream of the canyon similarly the modern channel long profile is distinctly and broadly convex through its great plains reach a unique feature among major rivers draining the eastern flank of the southern rocky mountain front radiocarbon dated charcoal from terrac

the blackwater draw formation quaternary a 1 4 plus m y record of eolian sedimentation and soil formation on the southern high plains the southern high plains of northwestern texas and eastern new mexico are mantled by a vast 100 000 km 2 sheet of quaternary eolian sediment locally as much as 27 m thick and termed the blackwater draw formation these sediments generally fine from southwest to northeast exhibiting a linear relationship of decreasing sand content and sand size and increasing silt content with increasing distance indicating the source area to be the pecos river valley as many as six well developed buried soils 2 5yr to 5yr hues bt horizons 1 2 m thick stage ii iii calcic horizons similar to the regional paleustalf and paleustoll surface soils occur in the formation the buried soils indicate episodic sedimentation separated by long periods of landscape stability eolian sedimentation probably occurred during prolonged aridity and stability and pedogenesis likely obtained during subhumid to semiarid conditions similar to those of the late quaternary the presence of the 0 62 m y lava creek b ash and the 1 4 m y guaje ash in the formation shows that the deposit accumulated throughout most of the quaternary data from paleomagnetic thermoluminescence and radiocarbon studies suggest that each cycle of sedimentation stability lasted for several hundred thousand years and that the last depositional event occurred at least several tens of thousands of years ago

potential of time lapse photography of snow for hydrological purposes at the small catchment scale time lapse photography provides an attractive source of information about snow cover characteristics especially at the small catchment scale the objective of this study was to design and test a monitoring system which allows multi resolution observations of snow cover characteristics the main aim was to simultaneously investigate the spatio temporal patterns of snow cover snow depth and snowfall interception in the area very close to the camera and the spatio temporal patterns of snow cover in the far range the multi resolution design was tested at three sites in the eastern part of the austrian alps hochschwab rax region digital photographs were taken at hourly time steps between 6 00 and 18 00 in the period november 2004 to december 2006 the results showed that the time lapse photography allows effective mapping of the snow depths at high temporal resolution in the region close to the digital camera at many snow stake locations it is possible to process a large number of photos by using an automatic procedure for accurate snow depth readings the digital photographs can also be used to infer the settling characteristics of the snow pack and snow interception during the day although it is not possible to directly estimate the snow interception mass the photos may indeed give very useful information on the snow processes on and beneath the forest canopy the main advantage of using time lapse photography in the far range of the digital camera is to observe the spatio temporal patterns of snow cover over different landscape configurations the results illustrate that digital photographs can be very useful for parameterising processes such as sloughing on steep slopes snow deposition in gullies and snow erosion on mountain ridges in a distributed snow model copyright 2011 john wiley sons ltd

an energy and mass model of snow cover suitable for operational avalanche forecasting a numerical model has been developed to simulate energy and mass evolution of snow cover at a given location as a function of meteorological conditions precipitation air temperature humidity wind velocity and incoming short wave and long wave radiation this model named crocus was first tested on a well instrumented field during a whole winter showing its ability to simulate the important phenomena affecting the evolution of the snow layers high temperature gradients wetting compaction and melting freezing cycles a second test was conducted at two locations in the french network used for operational avalanche forecasting though the weather observations are made there only twice daily the snow profiles calculated by the model were very close to those obtained once a week by a pit observation crocus proved itself sufficient to be considered now as a useful objective tool for operational avalanche forecasting

soils and landscape evolution of eolian plains the southern high plains of texas and new mexico holliday v t 1990 soils and landscape evolution of eolian plains the southern high plains of texas and new mexico in p l k knuepfer and l d mcfadden editors soils and landscape evolution geomorphology 3 489 515 sheets of eolian sediment cover many areas of the earth s surface sand seas dune fields and loess sheets being the best known examples of such features less well known are deposits of sandy eolian sediment forming extensive plains an excellent example of such a region is the semi arid southern high plains northwest texas and eastern new mexico the level landscape of the area was created by depositon of multiple extensive 80 000 km 2 sheets of eolian sediment biackwater draw formation over the past 1 4 ma this deposit grades from sandy southwest to silty and clayey northeast and is up to 27 m thick surface soils at least 30 000 and possibly 120 000 years old are well developed 5yr hues agrillic horizons 1 2 m thick with prismatic structure stage ii iii calcic horizons and are generally paleustolls and paleustalfs with some paleargids and haplargids morphologic variation is due mainly to textural variation of the eolian parent material although locally thickness of the parent material and wind erosion and cumulization are important factors and locally slight variation in effective precipitation may be significant the blackwater draw formation contains as many as six well developed buried soils each formed in individual layers of eolian sediment similar to or more strongly expressed 2 syr hues higher illuvial clay content than the regional surface soils the presence of the buried soils indicates that sedimentation was episodic and separated by long periods of relative landscape stability eolian processes also appear to have been important during the periods of stability and pedogenesis by providing clayey calcareous dust that was added to the soil promoting formation of the argillic and calcic horizons the sedimentologic and pedologic uniformity of the deposit suggests that the regional environment has not varied significantly during the quaternary except for periods of increased sedimentation or wind deflation underlying the blackwater draw formation is an upper tertiary deposit up to 36 m thick of eolian sand silt and clay ogallala formation this deposit contains buried soils very similar to those in the blackwater draw formation suggesting that the geomorphic processes that created the quaternary landscape of the southern high plains began to operate in the late tertiary perhaps as much as 11 million years ago

conditions favourable for the formation of warm climate aeolian sand sheets aeolian sand sheets are areas of aeolian sand where dunes with slipfaces are generally absent sand sheets are ubiquitous to modern warm climate sand seas generally occurring marginal to dune fields although they may exist within the interior of a sand sea or independent of a dune field sand sheet deposits are recognized in ancient aeolian sequences where they may account for significant accumulations of low angle aeolian stratification we suggest that the occurrence of sand sheets instead of dunes indicates that conditions are outside the range within which dunes form or that one or more factors interfere with dune development while also favouring the accumulation of sand sheets a study of six modern sand sheets in north america located at great sand dunes gran desierto dumont algodones padre island and colorado river delta indicates that the factors favourable for sand sheet development are 1 a high water table 2 surface cementation or binding 3 periodic flooding 4 a significant coarse grained sediment population and 5 vegetation these factors are reflected in the nature of stratification and the accessory features of sand sheet accumulations within the areas of modern sand sheets as well as in their ancient counterparts in the triassic dolores and pennsylvanian permian rico formations

snow depth structure fractal behavior and interannual consistency over haut glacier d arolla switzerland snow depth patterns over glaciers are controlled by precipitation snow redistribution due to wind and avalanches and the exchange of energy with the atmosphere that determines snow ablation while many studies have advanced the understanding of ablation processes less is known about winter snow patterns and their variability over glaciers we analyze snow depth on haut glacier d arolla switzerland in the two winter seasons 2006 2007 and 2010 2011 to 1 understand whether snow depth over an alpine glacier at the end of the accumulation season exhibits a behavior similar to the one observed on single slopes and vegetated areas and 2 investigate the snow pattern consistency over the two accumulation seasons we perform this analysis on a data set of high resolution lidar derived snow depth using variograms and fractal parameters our first main result is that snow depth patterns on the glacier exhibit a multiscale behavior with a scale break around 20 m after which the fractal dimension increases indicating more autocorrelated structure before the scale break than after second this behavior is consistent over the two years with fractal parameters and their spatial variability almost constant in the two seasons we also show that snow depth patterns exhibit a distinct behavior in the glacier tongue and the upper catchment with longer correlation distances on the tongue in the direction of the main winds suggesting spatial distinctions that are likely induced by different processes and that should be taken into account when extrapolating snow depth from limited samples

soil geomorphic relations of lamellae in eolian sand on the high plains of texas and new mexico clay lamellae are ubiquitous features in sands in a wide variety of settings around the world most studies of lamellae focus on 1 a few or individual locales or on 2 formation by experimental methods in the laboratory this study reports on lamellae from eight localities in three late quaternary dune fields on the southern high plains of northwest texas and eastern new mexico most lamellae observed are illuvial and they increase in number and thickness through time a few 1 3 thin 1 2 mm lamellae formed in historic sediments lamellae are more numerous 3 12 and thicker 3 5 mm in older late holocene b 1000 14 c years bp and middle holocene b 7600 14 c years bp sands soils that formed through the late pleistocene and into the early holocene 14 300 7600 14 c years bp or soils that formed throughout the holocene can exhibit as many as 30 lamellae or lamellae of 10 12 mm thickness the micromorphology of the lamellae shows that argillans on sand grains are thicker more laminated more continuous and cap and link more grains through time other variables affect lamella morphology within individual dunes the lamellae are best expressed where the sand is thickest they decrease in number and thickness as sand thins the lamellae also form only in clean well drained sand poor drainage and or bioturbation result in formation of a continuous argillic horizon encasing lamellae d 2005 elsevier b v all rights reserved

retention of crab larvae in a coastal null zone alongshelf transport in the southern middle atlantic bight is forced by buoyancy driven currents originating in three large estuaries along the bight these currents are strongest in the coastal ocean near the southern terminus of each estuary while the analogous region on the northern side is characterized by weak subtidal flow we used a combination of field observations and numerical modeling to test the hypothesis that these regions of weak subtidal flow are coastal null zones that serve as retention areas for larvae the field study consisted of a four day shipboard investigation of the distribution of blue crab larvae callinectes sapidus near the mouth of delaware bay 39 n 75 w in late summer 2004 hydrographic surveys of the study site were conducted with a hull mounted surface measuring system results showed a sharp boundary between the null zone and the buoyancy driven current to the south blue crab larvae were collected in surface plankton tows along a 30 km transect that encompassed these two areas stations with higher densities of larvae were clustered in the null zone during both ebb and flood tides a numerical model was used to examine the physical mechanisms responsible for the observed distribution model results agreed with the field survey and showed that simulated larvae are aggregated in the null zone the simulations also demonstrated that larvae spawned within the null zone have a much greater probability of settling in juvenile nursery habitat within the bay the close agreement between field and model results provides consistent support for the hypothesis that coastal null zones associated with the buoyancy driven circulation of large estuaries may allow retention of larvae in the vicinity of the natal spawning population

geoarchaeology and geochronology of the miami clovis site southern high plains of texas abstract the miami site excavated in 1937 is in a small playa basin on the high plains surface the site is one of the earliest documented co occurrences of clovis points and mammoth reinvestigation of the site and related collections was undertaken to better understand the stratigraphy geochronology and archaeology the basin 23 m diameter 1 6 m deep filled with 1 dark gray silty clay and 2 near the top of the section a lens of well sorted silt or loess the basin started to fill ca 13 700 yr b p the loess dates to ca 11 400 yr b p and the bone bed probably dates to ca 11 400 10 500 yr b p the loess may be the local manifestation of a clovis drought the partial remains of five mammoths three adults and two juveniles were recovered in 1937 no other animal remains are known the bone is heavily weathered and there are no clear indications of human modification artifacts found at the site include three clovis points and a scraper found among the bones and two flakes and a scraper found on the surface near the playa the origins of the bone and stone assemblage are uncertain but four scenarios are offered a successful mammoth kill an unsuccessful kill with wounded animals dying at the watering hole opportunistic scavenging following natural deaths or a palimpsest of multiple deaths following both natural and human causes

snow atmosphere coupled simulation at dome c antarctica using a snow atmosphere coupled model the evolution of the surface and near surface snow temperature is modeled at dome c antarctica during the period 20 30 january 2010 firstly the detailed multilayer snow model crocus is run in stand alone mode with meteorological input forcing data provided by local meteorological observations the snow model is able to simulate the evolution of surface temperature with good accuracy it reproduces the observed downward propagation of the diurnal heatwave into the upper 50 cm of the snowpack reasonably well secondly a fully coupled 3 d snow atmosphere simulation is performed with the arome regional meteorological model for which the standard single layer snow parameterization is replaced by crocus in spite of a poor simulation of clouds the surface and near surface snow temperatures are correctly simulated showing neither significant bias nor drifts during the simulation period the model reproduces particularly well the average decrease of the diurnal amplitude of air temperature from the surface to the top of the 45 m instrumented tower this study highlights the potential of snow atmosphere coupled models over the antarctic plateau and the need to improve cloud microphysics and data assimilation over polar regions

late quaternary loess landscape evolution on an active tectonic margin charwell basin south island new zealand abstract loess deposits constitute an important archive of aeolian deposition reflecting wider patterns of glacial atmospheric circulation and more localised interactions between riverine source areas loess trapping efficiency and geomorphic controls on erosion rate conceptual models have been formulated to explain the coeval evolution of loess mantles and associated landscapes loess landscape models but none apply to areas of tectonically induced base level lowering this study uses an age sequence of alluvial fill terraces in the charwell basin north eastern south island new zealand which straddles the transpressive hope fault to investigate geomorphic controls on loess landscape evolution in an active tectonic region we hypothesize that the more evolved drainage networks on older terraces will more effectively propagate base level lowering by way of a greater areal proportion of steep and convex hillslopes and a smaller proportion of non eroding interfluves eventually as the proportion of interfluves diminishes and hillslope convexity increases terraces shift from being net loess accumulators to areas of net loess erosion we investigate the nature of erosion and the geomorphic thresholds associated with this transition morphometric analysis of alluvial terraces and terrace remnants of increasing age demonstrated geomorphic evolution through time with a decrease in extent of original planar terrace tread morphology and an increase in frequency of steeper slopes and convexo concave land elements the number of loess sheets and the thickness of loess increased across the three youngest terraces the next oldest ca 150 ka terrace remnant had the greatest maximum number of loess sheets 3 and loess thickness 8 m but the loess mantle was highly variable a detailed loess stratigraphic analysis and the morphometric analysis place this terrace in a transition between dominantly planar uniformly loess mantled landforms and loess free ridge and valley terrain exemplified by the oldest terrace remnant variations in thickness and preservation of loess sheets demonstrated spatially and temporally variable erosion during loess accumulation to test our hypothesis of loess persistence we calculated critical steady state hillslope curvatures from a soil transport model calibrated for the study area above which the uppermost loess sheet l1 max thickness 1 8 m should be completely eroded we compared loess distribution mapped in the field to values of slope curvature calculated from topographic surveys and found two of three critical curvature values had acceptable predictive ability where predictions failed this is probably due to transient responses related to active steam incision because all critical curvature values predicted presence of loess on the oldest terrace remnant where there is none we conclude that important factors other than morphometric ones are important in determining loess distribution in loess landscapes in active tectonic regions these may include internal changes to regolith affecting erodibility or vegetation or topographic interaction with wind patterns affecting loess trapping

paleosols in clastic sedimentary rocks their geologic applications interest in pre quaternary paleosols has increased over the past decade in large part because they have proved to be beneficial in solving diverse geological problems the majority of paleosols are described from continental deposits most commonly from alluvial strata criteria for recognizing these paleosols have been extensively described however classifying them has proved more complicated pre quaternary paleosols are generally classified according to one or more modern soil classification systems although one new classification has been proposed exclusively for paleosols to avoid problems using the modern soil classifications in addition to taxonomic classification paleosols can be categorized according to the interplay among deposition erosion and the rate of pedogenesis when they formed paleosols can be solitary if they formed during a period of landscape stability following the development of an unconformity such paleosols are commonly thick and extremely well developed more commonly paleosols are vertically stacked or multistory because they formed in sedimentary systems undergoing net aggradation if erosion was insignificant and sedimentation was rapid and unsteady compound paleosols generally formed if the rate of pedogenesis exceeded the rate of deposition composite paleosols developed thick cumulative paleosols indicate that erosion was insignificant and that sedimentation was relatively steady both autogenic and allogenic processes can influence depositional and erosion patterns and thus affect the kinds of soils that form consequently paleosols can help to interpret the history of sediment deposition and the autogenic and allogenic processes that influenced a sedimentary basin paleosols are also helpful in stratigraphic studies including sequence stratigraphic analyses they are used for stratigraphic correlations at the local and basinal scale and some workers have calculated sediment accumulation rates based on the degree of paleosol development in addition to their stratigraphic applications paleosols can be used to interpret landscapes of the past by analyzing paleosol landscape associations at different spatial scales ranging from local to basin wide in scope at the local scale lateral changes in paleosol properties are largely the result of variations in grain size and topography at the scale of the sedimentary basin paleosols in different locations differ because of basinal variations in topography grain size climate and subsidence rate paleosols are used to reconstruct ancient climates even to estimate ancient mean annual precipitation map and mean annual temperature mat ancient climatic conditions can be interpreted from modern soil analogs or by identifying particular pedogenic properties that modern studies show to have climatic significance stable carbon and oxygen isotopes are also used to interpret ancient climate and some effort has been made to estimate mat from isotopic composition on the basis of

long quaternary record in eastern washington u s a interpreted from multiple buried paleosols in loess loess that is from a few meters to 75 m thick covers an area of more than 20 000 km2 on the columbia plateau in washington idaho and oregon the region of deepest loess is in eastern washington and is called the palouse the palouse is downwind of the channeled scabland through which massive outburst floods from glacial lake missoula flowed repeatedly during glacial stages of the pleistocene the deepest stratigraphic section yet studied is in a remnant of the once continuous loess cover that is surrounded by scabland channels a normal over reverse magnetic polarity zonation in this section supports an age of more than 790 000 yr but 15 35 m of loess may be present beneath this section so a total of 1 5 2 million yr is possible upward fining of texture in some layers in the loess at this site and stratigraphic evidence at nearby sites suggest that at least some pulses of loess deposition were triggered by episodes of cataclysmic floods nineteen or more individual paleosols can be recognized in 26 m of section based on field morphology physical and chemical properties and micromorphology the paleosols consist of calcic petrocalcic and duripan horizons many of which are associated with cambic horizons less strongly developed soils in this and other sections have been obscured by partial overlap of soil development in an episodically rising loess landscape paleosols in the loess at other sites reflect a dry to moist climatic gradient from west to east across the region during the pleistocene that was grossly similar to today s accumulation of pedogenic carbonates and silica dominates in a western zone where the present day mean annual precipitation is less than about 450 mm translocation of silicate clays and leaching of carbonates dominate in a central steppe zone where precipitation is between 450 and about 700 mm fragipans are common in an eastern zone along the steppe forest transition at present day precipitation of over 700 mm reconnaissance study suggests that these climatic pedogenic zones have been somewhat stable during many of the episodes of soil development preserved in the loess although some paleosols have different features from the majority of the paleosols in that zone e g paleosols with fragipans in a sequence of paleosols with argillic horizons which suggests that some episodes of soil development took place under different climatic conditions

early and middle holocene soils at the lubbock lake archeological site texas summary two buried soils have been identified in early and middle holocene sediments at the lubbock lake site a well stratified archeological locality in yellowhouse draw lubbock county texas the firstview soil formed in organic rich lacustrine and sandy eolian sediments deposited from 11 000 to 8 500 yr b p the soil developed from 8 500 to about 6 300 yr b p and exhibits o a c and a c profiles the lacustrine facies found along the valley axis has a relatively high organic matter content contains abundant silicified root remains and commonly exhibits a gley horizon immediately below the a horizon indicating that the soil formed in a marsh with the water table at or just below the surface the soil becomes coarser grained better drained and weakly calcareous toward the valley margin reflecting the facies change in parent material the overlying yellowhouse soil formed in highly calcareous lacustrine sediments along the valley axis and sandy eolian material along the valley margin with deposition and pedogenesis occurring between 6 300 and 5 000 yr b p the soil exhibits a c and sometimes a b c profiles the relatively high organic matter content of the a horizon and minimal leaching of carbonate in the c horizon of the valley axis facies suggest that the water table was high during pedogenesis the valley margin facies of the soil exhibits some evidence of clay illuviation the contrasting field and chemical characteristics of the valley axis facies of the two soils and the sedimentological data indicate a sudden change in the water geochemistry and local environmental change soils with morphologies parent material and age similar to that of the firstview soil are not common in valley fills on the southern high plains whereas soils similar to the yellowhouse soil are widespread these data indicate a regional climatic change toward conditions of increased eolian activity reduced effective moisture and possibly warmer temperatures