aerodynamic roughness of fixed sandy beds the nature of interactions between surface winds and sand surfaces that can be characterized by aerodynamic roughness length has important implications for aeolian sediment transport here we report the wind tunnel results of systematic tests of the aerodynamic roughness lengths of different sized fixed sand beds at different free stream wind velocities the results suggest that there are complex variations of aerodynamic roughness length wind is an active factor in determining the aerodynamic roughness length of fixed sand beds the so called 1 30 law in aeolian research proposed by bagnold more than a half century ago for sand surfaces is found to suffer some limitations some multivariate models relating aerodynamic roughness length and other factors are provided the differences between the aerodynamic roughness of fixed and mobile beds are discussed and it is implied that mobile surfaces adapt to the wind by changing roughness the similarities between aerodynamic roughness and hydraulic roughness are compared aerodynamic roughness is divided into aerodynamically smooth transitional and completely rough regimes

near field sea level variability in northwest europe and ice sheet stability during the last interglacial global sea level during the last interglacial lig marine isotope sub stage 5e peaked between c 5 5 and 9 m above present implying significant melt from greenland and antarctica relative sea level rsl observations from several far and intermediate field sites suggest abrupt fluctuations or jumps in rsl during the lig highstand that require one or more episodes of ice sheet collapse and regrowth such events should be manifest as unique sea level fingerprints recorded in far intermediate and near field sites depending on the source s of ice mass change involved to date though no coherent evidence of such fluctuations has been reported from near field rsl studies in northwest europe this is an important problem because rsl fluctuations during the lig are portrayed as warning signs for how polar ice sheets may behave in a future warmer than present world here we review the evidence for rsl change during the lig using stratigraphic data from the best resolved highstand records that exist in the near field of northwest europe from a range of settings that include lagoonal shallow marine tidal flat salt marsh and brackish water fluviatile environments consideration of previously published stratigraphic records from two sites in the eemian coastal marine embayment that existed in the central netherlands yields no clear indications for abrupt rsl change during the attainment of the near field highstand nor do we find any such indications common to other records from countries bordering the north sea the baltic sea and the white sea two modelling experiments that explore the global signal of hypothetical sea level oscillations caused by partial collapse and regrowth of either the greenland or antarctic lig ice sheet show that the north sea region is relatively insensitive to mass changes sourced from greenland but should clearly register events with an antarctic origin especially those that occur late in the lig the lack of evidence for abrupt sea level fluctuations at this time in northwest europe concurs with a lack of clear near field evidence for ice sheet collapse

formal subdivision of the quaternary system period past present and future abstract the quaternary system period represents the past 2 58 million years and is officially subdivided into the pleistocene and holocene series epochs with the base of the holocene assigned an age of 11 700 calendar years before ad 2000 the two lowest stages of the pleistocene the gelasian base 2 58 ma and the calabrian base 1 80 ma have been ratified and these effectively constitute the lower pleistocene subseries all other official subdivisions are pending for the middle pleistocene subseries three candidate global boundary stratotype sections and points gssps are under consideration the valle di manche in calabria and montalbano jonico in basilicata both in southern italy and the chiba section in japan the matuyama brunhes chron boundary 773 ka serves as the principal guide for the base of the middle pleistocene the base of the upper pleistocene subseries is generally agreed to coincide approximately with that of the last interglacial marine isotope substage 5e 130 ka the fronte section near taranto in southern italy represents a possible candidate gssp but an antarctic ice core might also serve this purpose a tripartite subdivision of the holocene with subseries stage boundaries at 8200 and 4200 years b p is also under consideration additional fine scale formal subdivision of the quaternary is being explored with the last glacial maximum serving as a test case the anthropocene is both an informal and undefined interval of time that includes the present day its duration formal informal status rank and method of definition are all under debate with one suggestion that it be defined as a formal unit beginning with the world s first nuclear bomb explosion on july 16th 1945 suggested and proposed gssps are compared and critiqued the history leading to ratification of the quaternary period in 2009 is examined drawing upon published and unpublished material

velocity profile of a sand cloud blowing over a gravel surface particle dynamic analyzer pda measurement technology was used to study the turbulent characteristics and the variation with height of the mean horizontal in the downwind direction and vertical in the upward direction particle velocity of a sand cloud blowing over a gravel surface the results show that the mean horizontal particle velocity of the cloud increases with height while the mean vertical velocity decreases with height the variation of the mean horizontal velocity with height is to some extent similar to the wind profile that increases logarithmically with height in the turbulent boundary layer the variation of the mean vertical velocity with height is much more complex than that of the mean horizontal velocity the increase of the resultant mean velocity with height can be expressed by a modified power function particle turbulence in the downwind direction decreases with height while that in the vertical direction is complex for fine sands 0 2 0 3 mm and 0 3 0 4 mm there is a tendency for the particle turbulence to increase with height in the very near surface layer 4 mm the movement of blown sand particles is very complex due to the rebound of particles on the bed and the interparticle collisions in the air wind starts to accelerate particle movement about 4 mm from the surface the initial rebound on the bed and the interparticle collisions in the air have a profound effect on particle movement below that height where particle concentration is very high and wind velocity is very low

the blake geomagnetic polarity episode recorded in chinese loess a geomagnetic anomaly consisting of three clearly defined periods of reverse polarity separated by two short intervals of normal polarity has been documented in a loess section near xining western china on the basis of previous studies of chinese loess stratigraphy we correlate this geomagnetic polarity episode with the blake event while more research is needed to improve our understanding of the exact process of remanence acquisition of loess deposits this study shows that loess may provide records of fast geomagnetic events and lends further support to the global nature of the blake geomagnetic event

comparison of measured wind tunnel and sweep simulated soil losses wind erosion estimates from the single event wind erosion evaluation program sweep model of the wind erosion prediction system weps were compared to wind tunnel experiments the influences of wind speed and soil texture were investigated from a previous study soil losses were measured directly in a wind tunnel using three soil types sandy loam loamy sand and sand each under three free stream wind speed conditions 10 18 and 26 m s 1 a different sand soil from another experiment was also tested under five wind speeds from 10 to 18 m s 1 over intervals of 2 m s 1 using a sediment trap and a flux profile estimating method the comparison of measured and estimated agricultural soil losses under non extreme winds less than 18 m s 1 in the wind tunnel was good the loamy sand comparison had an error less than 6 while the sandy loam soil had an error of about 35 sweep underestimated the amount of erosion with the sand soil however because the estimating equations used in sweep to predict soil parameters for agricultural soils are not directly applicable to pure sand surfaces this was expected when conducting sweep simulations it is recommended to use the actual aggregate size distribution asd data if available rather than relying on sweep s asd parameter values being estimated from other soil properties c 2013 elsevier b v all rights reserved

quaternary geology of eastern germany saxony saxon anhalt south brandenburg thuringia type area of the elsterian and saalian stages in europe abstract the characteristic feature of the quaternary geology of eastern germany location map fig 1 is a sequence of more than 50 horizons and complexes of glacial laminated clays tills glaciofluvial sediments and periglacial river gravels gelifluction sheets alluvium loess facies in the period between the younger tertiary and the first elsterian continental glaciation at least four gravel terraces were built up under cold climate conditions the youngest of these gravel bodies lacks scandinavian rocks and is interbedded with elsterian glaciolacustrine deposits pre elsterian temperate periods have been recorded at a number of places i e zeuchfeld untermassfeld voigtstedt sussenborn two major ice advances with additional minor oscillations have been identified of elsterian and saalian ages complete eemian and holsteinian sequences are represented showing vegetational development through each interglacial cycle cool temperate warm cool the weichselian glacial stage in eastern germany is represented by thick periglacial sedimentation including gravels gelifluction sheets alluvium debris covers and loess within these sediments is a wide variety of glaciotectonic structures and periglacial soil structures including classical involutions and ice wedge casts an outline of the present state of knowledge of the quaternary of eastern germany is given in tables 1 3 while table 4 presents a stratigraphical comparison with the neighbouring regions and countries the palaeogeography of the region during the periods of the european continental glaciation is depicted in fig 2

geomagnetic excursions knowns and unknowns geomagnetic excursions are short lived episodes when earth s magnetic field deviates into an intermediate polarity state understanding the origin frequency amplitude duration and field behavior associated with excursions is a forefront research area within solid earth geophysics recent advances in excursion research are summarized here and key further research is suggested to resolve major unanswered questions improving the global distribution of excursion records particularly from the southern hemisphere obtaining high resolution sedimentary excursion records with good age control from sites with sedimentation rates 10 cm kyr obtaining volcanic excursion records coupled with high precision geochronology and estimating excursion duration with high chronological precision will all facilitate hypothesis testing concerning the deep earth dynamics that generate geomagnetic excursions

evidence for the blake event recorded at the eemian archaeological site of caours france a palaeomagnetic study of the last interglacial calcareous tufa sequence at the archaeological site of caours northern france identified a geomagnetic excursion that we interpret as the blake event earlier palaeontological molluscs mammals and geochemical proxy studies at this site allowed recognition of full interglacial conditions prevailing during the deposition of the tufa sequence the tufa sequence and associated palaeolithic levels have been dated to the eemian interglacial by a set of tims u th measurements on calcitic concretions average 123 3 ka by previous correlations of the blake event with the eemian sensu stricto as defined in the netherlands pollenzones at neumark nord 2 germany and rutten the netherlands it has been shown that the continental eemian starts after the peak of marine isotope stage mis 5e the identification of the blake event at caours implies a post mis 5e peak age for all four levels of the palaeolithic occupation in perspective of the time lag between the mis 5e peak and the beginning of the eemian identified in other studies it is very likely that during the main occupation of caours a significant barrier was in place between north western france and great britain in the form of the english channel it is possible that the chronological position of the last interglacial environments in northwestern europe in relation to sea level change is a key factor behind the apparent absence of last interglacial palaeolithic sites in great britain

a geomagnetic event recorded in loess deposits of the tonchesberg germany identification of the blake magnetic polarity episode summary high resolution palaeomagnetic studies on a collection of nearly 350 specimens taken from a 1 30m thick section of an upper pleistocene loess profile from the tonchesberg germany are described the blake magnetic polarity episode is recorded in a layer above the partly eroded palaeosol of the eemian interglacial it is identified by its stratigraphic position and thermoluminescence data 90 0110 0 kyr zoller conard hahn 1991 frechen 1991 1992 magnetite and haematite contribute to the natural remanent magnetization nrm directional behaviour during thermal and alternating field cleaning suggests that magnetite carries a primary post depositional remanent magnetization pdrm and haematite a secondary chemical remanent magnetization crm of early diagenetic origin

the blown sand flux over a sandy surface a wind tunnel investigation on the fetch effect abstract detailed wind tunnel tests were conducted to examine the fetch effect of a sandy surface on a sand cloud blowing over it the results suggest that the fetch length of a sandy surface has a significant effect on both the vertical flux profile and total horizontal flux the sand flux over a sandy surface increases with height in the very near surface layer but then decays exponentially in agreement with the widely accepted conclusion the decay function can be expressed by q aexp h b where q is the sand flux at height h coefficient a that tends to increase with wind speed implies the influence of wind while coefficient b that defines the relative decay rate shows the influence of both the fetch and wind the relative decay rate increases with fetch when the fetch length is short then becomes constant when the fetch reaches a certain length the threshold fetch length over which the relative decay rate keeps constant increases with wind speed the average saltation height generally increases with fetch both the relative decay rate and average saltation height show that the fetch effect on the flux profile becomes more significant when the wind speed increases the total sand transport equation for the total fetch can be expressed by q c 1 ut u 2u3 g where q is the total sand transport rate u and ut are the wind velocity and threshold wind velocity at the centerline height of the wind tunnel respectively g is gravitational acceleration is the density of air and c is a proportionality coefficient that increases with the fetch length implying that the total sand flux increases with the fetch length

short term dynamics of wind erosion of three newly cultivated grassland soils in northern china this study examined the dynamic nature of short term wind erosion processes of three grassland soils under simulated cultivation in a laboratory wind tunnel soil loss on a sandy loam a loamy sand and a sand soil was measured in six successive 10 3 and 1 min exposures at the speeds of 10 18 and 26 m s 1 respectively erodible soil particle sizes of each interval were determined through direct dry sieving it was observed that increasing blowing duration generally led to rapid decrease of soil loss decrease of the erodible soil particle size from a definitely restricted area by any definite speed of wind and the non erodible particles remaining on the soil surface increased from the first to the last blowing interval soil loss decreased by 86 4 94 8 at 10 m s 1 in 60 min 90 0 95 4 at 18 m s 1 in 18 min and 71 5 97 8 at 26 m s 1 in 6 min the results indicate that wind erosion on the newly cultivated soils is most intense during the initial blowing the decrease of soil loss with time is presumed due to modification of soil surface by blowing wind i e the concentration of non erodible aggregates with the deflation of the erodible particles on the soil surfaces

evidence for the early onset of the ipswichian thermal optimum palaeoecology of last interglacial deposits at whittlesey eastern england fossiliferous deposits infilling a channel at whittlesey eastern england are dated by amino acid racemization to the last interglacial and pollen analysis indicates deposition in ipswichian biozones ip ib and ip iib multidisciplinary palaeoenvironmental analyses of these deposits provide a rare insight into ip ib subzone conditions specifically the ip ib deposits contain exotic thermophiles naias minor belgrandia marginata bembidion elongatum pelochares versicolor caccobius schreberi onthophagus massai and emys orbicularis usually associated with ip iib combined palaeotemperature reconstructions based on beetle ostracod and vertebrate assemblages of the ip ib deposits indicate that summers mean july range 19 to 22 c were at least 2 c warmer than at present whereas winters mean january air temperature range 0 to 7 c were probably similar to those of today these palaeotemperature ranges encompass those for ip iib deposits at trafalgar square 20 to 21 c and 1 5 to 3 c previously considered the only ipswichian site to record temperatures significantly warmer than holocene temperatures of particular significance is that thermal optimal conditions commenced in ip ib rather than being confined to ip iib this demonstrates rapid warming and biological response to early ipswichian climate amelioration which accords with the deep sea last interglacial and european eemian records supplementary material supplementary tables s1 s7 are available at http doi org 10 6084 m9 figshare c 3830221

direct terrestrial marine correlation demonstrates surprisingly late onset of the last interglacial in central europe an interdisciplinary study of a small sedimentary basin at neumark nord 2 nn2 germany has yielded a high resolution record of the palaeomagnetic blake event which we are able to place at the early part of the last interglacial pollen sequence documented from the same section we use this data to calculate the duration of this stratigraphically important event at 3400 350 yr more importantly the neumark nord 2 data enables precise terrestrial marine correlation for the eemian stage in central europe this shows a remarkably large time lag of ca 5000 yr between the mis 5e peak in the marine record and the start of the last interglacial in this region

geomagnetic moment variation and paleomagnetic excursions since 400 kyr bp a stacked record from sedimentary sequences of the portuguese margin abstract a paleomagnetic study was performed in clayey carbonate sedimentary sequences deposited during the last 400 kyr on the portuguese margin northeast atlantic ocean declination and inclination of the stable remanent magnetization present recurrent deviations from the mean geomagnetic field direction the normalized intensity documents a series of relative paleointensity rpi lows recognized in other reference records three directional anomalies occurring during rpi lows chronologically correspond to the laschamp excursion 42 kyr bp the blake event 115 122 kyr bp and the icelandic basin excursion 190 kyr bp a fourth directional anomaly recorded at 290 kyr bp during another rpi low defines the portuguese margin excursion four non excursional rpi lows are recorded at the ages of the jamaica pringle falls mamaku calabrian ridge 1 and levantine excursions the rpi record is characterized by a periodicity of 100 kyr paleointensity lows often coinciding with the end of interglacial stages this record sets the basis of the construction of an authigenic 10be 9be record from the same sedimentary sequences carcaillet et al this issue

extracting historic cyclone data from coastal dune deposits in eastern hainan island china abstract understanding long term large cyclone activity is critical for coastal management and disaster prevention and mitigation particularly with projected rising sea level and increasing cyclone frequency and the intensity here we present sedimentary evidence cyclone overwash deposits beachrock boulders and cyclone induced clastic deposits of historic large cyclone events from coastal dune deposits on eastern hainan island china based on luminescence dating and sedimentological analysis eight historic tropical cyclone events at 1095 90 bce 900 1000 bce 975 50 ce 1720 20 ce 1740 35 ce 1790 25 ce 1850 15 ce and 1895 10 ce have been identified in this region the elevation of the termination point of cyclone overwash deposit layers that represent the paleo cyclone minimum wave run up stage in combination with knowledge of present day cyclone events was applied to assess the intensity of these extreme events the intensity of these cyclone events was likely greater than that of cyclones in the local instrumental records furthermore these large cyclone events correspond to historic records of devastating cyclones through comparison with regional and global climate records we infer that the variability of large cyclones in the south china sea was probably modulated by the el nino southern oscillation western pacific warm pool and local sea surface temperatures over the past 3400 yr these results provide an improved understanding of long term extreme cyclone events and their response to climate change thereby contributing to regional planning and coastal defense strategies

fluvial evolution of the rhine during the last interglacial glacial cycle in the southern north sea basin a review and look forward this paper presents the current state of knowledge on the evolution and depositional history of the river rhine in the southern part of the north sea basin during the upper middle and late pleistocene and its response to climate change sea level oscillation and glacio isostasy the study focuses on the development of the eemian interglacial lower delta in the central netherlands and its relation to records of climate and sea level rise and uses the saalian and weichselian pre and postdating periods to place its development in context the rhine fluvial system fills the gradually subsiding north sea basin but its development has strongly been affected by the saalian glaciation and its remaining topography ice pushed ridges originating off the limit of maximum glaciation basically divided the central netherlands into two sedimentary depocentres a central depocentre within the former ice limit and a southern depocentre south of it the sedimentary record of the central depocentre including an incised valley fill shows a 20 40m thick stacked sequence consisting of three units the incised valley fill consists of a late saalian to early eemian age lower fluvial unit and a weichselian age upper fluvial unit both composed of coarse grained channel deposits sandwiched in between is a 5 15m thick record composed of fine grained fluvial and estuarine tidal floodbasin and shallow marine deposits it is of eemian interglacial and early weichselian age and comprises transgressive and highstand deposits that show the drowning of a fluvial system inland parts transformed from fluvial to deltaic and estuarine environments and the most downstream parts transformed to a shallow marine embayment preservation of these units occurred despite considerable sea level fall and climate controlled erosion taking place in the last glacial preservation potential was increased by the fact that the rhine system avulsed away to the southern depocentre halfway the weichselian pleniglacial consequently the infill of the southern depocentre is of an entire different nature and last interglacial transgressive or highstand units are hardly preserved because of glaciation and resulting depocentre configuration the netherlands in nw europe thus offers a very good opportunity to study the transgressive interglacial lower deltaic records and falling stage preservation thereof both key elements for understanding sedimentary development over full 100 ky glacial interglacial cycles of climate and base level change 2014 elsevier ltd and inqua

thermoluminescence dates for the middle palaeolithic site of chez pinaud jonzac france thermoluminescence dating of heated flint artefacts from the middle palaeolithic sequence of chez pinaud jonzac france places an assemblage of quina type mousterian into mis 4 while the overlying assemblage of denticulate mousterian which is followed by two layers with mousterian of acheulean tradition are all assigned to mis 3 tl dating is used to verify the mixed nature of deposits from which diagnostic middle as well as upper palaeolithic tools were recovered the tl ages are significantly different for samples from this layer and broadly agree with the archaeological attributions while the study is generally limited by the low number of heated samples available a correlation with a generalized chronostratigraphic sequence is possible by including proxy data from the faunal remains associated with the lithic assemblages in question the quina mousterian in southwestern france therefore can be placed by chronometric dating methods in mis 4 to mis 3

the classic marine isotope substage 5e since its identi cation nearly fty years ago marine iso tope stage 5 mis 5 has been placed onto absolute time scaleson the basis of three independent approaches cesare emiliani who set up the isotope stages emiliani 1955 depended onuranium series dating of the sediments a method that today isregarded as not generally capable of yielding useful precisionor accuracy broecker and van donk 1970 pioneered the ap proach of correlating to radiometrically dated marine coral ter races thishasbeenmuchaidedinrecentyearsbyimprovementsin the precision and accuracy of these age determinations thathave owed from the development of thermal ionization massspectrometry tims for uranium series dating edwards

the last interglacial climate during the last 10 000 years the holocene has been relatively mild and stable in contrast the climate during the last interglacial is often portrayed as more variable but as kukla discusses in this perspective evidence for a more stable last interglacial is emerging furthermore the transition to the next glacial proceeded in stages and was not uniform across europe

strong continentality and effective moisture drove unforeseen vegetation dynamics since the last interglacial at inland mediterranean areas the villarquemado sequence in ne iberia abstract few continental palaeoenvironmental sedimentary sequences from southern europe are long enough to span the last interglacial period marine isotopic stage mis 5 the last glacial cycle mis 4 to 2 and the holocene el canizar de villarquemado north eastern iberian peninsula is an exceptional sedimentary lacustrine sequence spanning the last ca 135 000 years of environmental change in an area of inland iberia characterized by mediterranean climate with strong continentality we present a multiproxy study which combines palynological sedimentological and geochemical analyses framed by an independent robust chronology hydrological and climate evolutions were reconstructed by sedimentological and geochemical proxies development of wetlands and shallow carbonate lakes support relatively humid conditions during mis 6 till the onset of mis 4 and during the holocene palaeohydrological conditions were drier during mis 5 dominance of peat environments than during the holocene more frequent carbonate producing lakes sedimentological evidence indicates extremely arid conditions during mis 3 with greater activity of alluvial fans prograding into the basin sedimentary facies variability highlights a large environmental and hydrological variability during mis 2 and a rapid humidity response to the onset of the holocene compared to classic mediterranean sites we found novel pollen assemblages for the end of mis 6 and mis 5 indicating that the vegetation cover was essentially represented by sustained high proportions of continentality adapted taxa dominated by juniperus during the relatively humid conditions since mis 6 till the onset of mis 4 higher evapotranspiration in inland iberia would have increased during periods of higher seasonal insolation maxima impeding soil development and the usual mesophyte expansion during interglacials observed in other mediterranean areas four main periods of forest development occurred in villarquemado during mis 5e mis 5c mis 5a and the holocene secondary peaks occurred also during mis 3 during colder but still relatively humid mis 4 junipers and mediterranean taxa disappear but some mesophytes and cold tolerant species persisted and pinus became the dominant tree up to modern times pollen assemblages and geochemical data variability suggest a dominant control of seasonality and the impact of north atlantic dynamics both during mis 5 cold events c18 c24 and full glacial conditions he and d o interstadials at millennial scales steppe herbaceous assemblages dominated during the extremely arid conditions of mis 3 and pines and steppe taxa during glacial period mis 2 villarquemado sequence demonstrates that the resilient behaviour of conifers in continental areas of inland southern european regions is key to understand the glacial interglacial vegetation evolution and to evaluate scenarios for potential impacts of global change

oxygen isotope analysis of equus teeth evidences early eemian and early weichselian palaeotemperatures at the middle palaeolithic site of neumark nord 2 saxony anhalt germany abstract here we present phosphate oxygen isotope 18opo4 data from horse equus sp tooth enamel bioapatite from early eemian and early weichselian find levels at the archaeological site of neumark nord 2 germany based on the relationship between 18opo4 of bioapatite body water local precipitation and air temperature these data are used to reconstruct palaeoclimatic conditions contemporary to the different phases of neanderthal activity at the site bulk enamel samples representing one year of growth were taken from horse teeth from early eemian nn2 2b 121 5 ka and nn2 1c and early weichselian nn2 0 93 7 ka find levels and 18opo4 values were then utilised to calculate 18o of local environmental water and mean annual air temperatures mats during these phases of mis5 results indicate that during the early eemian mat was 9 c with some evidence of variability through time although 3 c lower the calculated early weichselian mat exceeds that indicated by other local and regional climate proxy datasets suggesting that neanderthal activity may have coincided with more ameliorate phases of the early weichselian in this area

the blake geomagnetic event transition geometry dynamical characteristics and geomagnetic significance abstract two records of the blake geomagnetic event have been obtained from marine cores in the mediterranean the upper bound for duration of the event calculated from accurate oxygen isotope stratigraphy and or tephrochronology is 4000 years one record is very detailed with 70 transitional directions and allows some characteristics of the event to be precisely retrieved the directional changes do not occur at constant speed rather a stop and go behaviour is observed as in detailed records of reversals the virtual geomagnetic pole vgp path confined to two bands of longitude over the americas and antipodal to them is virtually identical to the only other path of this event obtained from lacustrine sediments in the western usa suggesting that a dipolar component may be present in the transitional field during the blake event the two bands of longitude coincide with those of many recent reversals suggesting that the physical processes leading to reversals or events are basically the same and that the same mechanism is statistically observed over long periods of time

the flux profile of a blowing sand cloud a wind tunnel investigation abstract the flux profile of a blowing sand cloud or the variation of blown sand flux with height is the reflection of blown sand particles that move in different trajectories and also the basis for checking drifting sand here we report the wind tunnel results of systematic tests of the flux profiles of different sized sands at different free stream wind velocities the results reveal that within the 60 cm near surface layer the decay of blown sand flux with height can be expressed by an exponential function q h a exp h b where q h is the blown sand transport rate at height h a and b are parameters that vary with wind velocity and sand size the significance of coefficient a and b in the function is defined a represents the transport rate in true creep and b implies the relative decay rate with height of the blown sand transport rate the true creep fraction the ratio of the sand transported on the surface h 0 to the total transport varies widely decreasing with both sand size and wind speed the flux profiles are converted to straight lines by plotting sand transport rate q h on a log scale the slope of the straight lines that represents the relative decay rate with height of sand transport rate decreases with an increase in free stream wind velocity and sand grain size implying that relatively more of the blown sand is transported to greater heights as grain size and wind speed increase the average saltating height represented by the height where 50 of the cumulative flux percentage occurs increases with both wind speed and grain size implying that saltation becomes more intense as grain size and or wind velocity increase

australopithecus sediba at 1 977 ma and implications for the origins of the genus homo newly exposed cave sediments at the malapa site include a flowstone layer capping the sedimentary unit containing the australopithecus sediba fossils uranium lead dating of the flowstone combined with paleomagnetic and stratigraphic analysis of the flowstone and underlying sediments provides a tightly constrained date of 1 977 0 002 million years ago ma for these fossils this refined dating suggests that au sediba from malapa predates the earliest uncontested evidence for homo in africa

a record of the blake event during the last interglacial paleosol in the western loess plateau of china abstract a high resolution record of the blake event has been obtained from a 40 m well dug in a loess section at jiuzhoutai in the city of lanzhou in the western loess plateau of china the paleomagnetic signal is principally carried by magnetite both in loess and paleosols the blake event is located at the boundary between paleosol s1 c of the last interglacial equivalent to mis 5e in deep sea records and loess l2 2 mis 5d and is characterized by a triple feature consisting of two short reversed intervals separated by a short normal interval the directional changes are abrupt as previously revealed in other records and suggest geocentric dipole field behavior before after and during the event but not necessarily during n r or r n transitions the age and duration of the event are estimated as between 119 97 and 114 47 kyr bp and 5 5 kyr respectively from thermoluminescence dating and astronomically tuned climate stratigraphy based on high resolution magnetic susceptibility

the terrestrial eemian to late weichselian sediment record at beckentin ne germany first results from lithostratigraphic palynological and geochronological analyses abstract over recent decades a growing number of well documented records from terrestrial last interglacial sites across central europe have substantially improved our understanding of eemian climate and landscape dynamics despite this progress there are also large areas from which little information is available thus constituting significant paleo geographic gaps in the last interglacial record among the regions with still inadequate paleo environmental information is the maritime influenced area of ne germany at the southern margin of the eemian baltic sea here we present first results from a geological investigation of a new last interglacial site recently discovered during archaeological excavations near beckentin sw mecklenburg the study area is located approximately 25 km to the south of the maximum mis 2 ice limit of the scandinavian ice sheet in ne germany and thus lies outside the weichselian belt of glaciation based on lithostratigraphic and sedimentological logging complemented by geochemical xrf and palynological investigations we divide the local succession into three sections 1 a basal facies comprising saalian till and associated glaciofluvial sand overlain by section 2 consisting of a fen peat which grades into laminated organic to minerogenic mud the organic deposits of section 2 preserve a near complete eemian pollen inventory encompassing pollen zones pz i to vi menke and tynni 1984 above this rest poorly sorted periglacial sands section 3 with ventifacts and evidence for cryogenic deformation geochronological results from 230th u dating of the buried organic rich deposits at beckentin show that these units accumulated in a former dead ice depression between 118 7 6 ka and 114 6 5 ka during the eemian interglacial high resolution optically stimulated luminescence osl profiling undertaken with a portable luminescence reader reveals a significant hiatus between the lacustrine fines and overlying periglacial cover sand five osl ages obtained from these cover sediments and the sand filling of an ice wedge cast show that these strata formed between during the last glacial interglacial transition

high resolution palynological record off the iberian margin direct land sea correlation for the last interglacial complex abstract we present high resolution pollen dinocyst and isotopic data for the last interglacial complex from marine core md952042 southwestern margin of the iberian peninsula 37 48 n 10 10 w 3148 m direct land sea correlation from this core indicates that during this period north atlantic sea surface temperatures were in phase with iberian climate our palynological analysis suggests a younger dryas like event at the marine isotope stage mis 6 5 transition the analysis also indicates that the eemian spans from the lightest isotopic values of mis 5e ca 126 ky bp to the heavier isotopic values towards the mis 5e 5d transition therefore the eemian is not entirely equivalent to mis 5e pollen analysis identifies four climatic phases of low amplitude during the eemian a mediterranean climate in southwestern europe is gradually replaced by oceanic conditions the middle of the eemian is characterized by an increase in precipitation on the land and ocean associated with a slight cooling this seems to be the result of a displacement of the polar front as far south as southern europe during this period after the eemian three relatively short climatic phases on land melisey i st germain ia and montaigu cold event occurred contemporaneously with three shifts of sea surface temperatures the montaigu event first identified in terrestrial pollen sequences is therefore also recorded in core md952042 on the basis of pollen dinocyst and planktonic isotopic data our results also show that the warm periods of mis 5 are not characterized by similar climatic conditions on land

transition from incised valley to barrier island systems during mis 5e in the northern chiba area kanto plain central japan abstract facies analysis together with palynostratigraphic studies of the kioroshi formation which lies beneath the northern chiba area of the kanto plain of central japan reveal the sedimentary processes in the fluvial to coastal settings during marine isotope stage mis 5e in this region the depositional sequence of the kioroshi formation comprises a lower incised valley system and an upper barrier island system the incised valley system consists of fluvial estuary and central basin facies with sandbar facies in the baymouth area in the study area the overlying barrier island system includes flood tidal delta spit and lagoon facies these facies form part of the barrier island system known as paleo tokyo bay which covered the present day kanto plain on the basis of palynostratigraphic correlation with the oxygen isotope curve in an offshore core md01 2421 the fluvial and estuary facies together with the lower half of the central basin facies of the incised valley system are interpreted to have accumulated during a sea level rise in the early stage of mis 5e the baymouth sandbar also developed and retrograded with the rising sea level and was abruptly covered by the central basin facies during the middle stage of mis 5e probably due to the migration of the sandbar to the outer bay area the abrupt change corresponds with the initial stage of development of the barrier island system the landward westward retreating bay ravinement erosion resulted in the transition to the barrier island system during middle mis 5e maximum transgression also occurred during middle mis 5e the back barrier lagoon was infilled during the late stage of mis 5e the sedimentary processes of the kioroshi formation are almost in accordance with the marine isotope curve

pleistocene rhine thames landscapes geological background for hominin occupation of the southern north sea region this paper links research questions in quaternary geology with those in palaeolithic archaeology a detailed geological reconstruction of the netherlands south west offshore area provides a stratigraphical context for archaeological and palaeontological finds progressive environmental developments have left a strong imprint on the area s palaeolithic record we highlight aspects of landscape evolution and related taphonomical changes visualized in maps for critical periods of the pleistocene in the wider southern north sea region the middle pleistocene record is divided into two palaeogeographical stages the pre anglian elsterian stage during which a wide land bridge existed between england and belgium even during marine highstands and the anglian elsterian to saalian interglacial with a narrower land bridge lowered by proglacial erosion but not yet fully eroded the late pleistocene landscape was very different with the land bridge fully dissected by an axial rhine thames valley eroded deep enough to fully connect the english channel and the north sea during periods of highstand this tripartite staging implies great differences in i possible migration routes of herds of herbivores as well as hominins preying upon them ii the erosion base of axial and tributary rivers causing an increase in the availability of flint raw materials and iii conditions for loess accumulation in northern france and belgium and the resulting preservation of middle palaeolithic sites 2011 john wiley sons ltd

heated flint tl dating for gruta da oliveira portugal dosimetric challenges and comparison of chronometric data the mousterian stratigraphy of gruta da oliveira torres novas portugal contains one of the latest occupations by neanderthals on the iberian peninsula thermoluminescence tl dates on heated flints were obtained for layers 13 and 14 and compared with the radiocarbon charcoal and burnt bone and u th secondary carbonates dating results available for those layers and the succession as a whole as the internal dose rates are very low the tl age estimates are very dependent on the external dose rates which show significant variation including indications of spatial patterning through close inspection of the radiation geometries of samples and dosemeters the appropriate gamma dosimetry is identified and the weighted mean tl ages 1 calculated accordingly are 55 7 ka for layer 13 and 77 8 ka for layer 14 these ages are stratigraphically consistent with the radiocarbon chronology for layers 9 11 and with the termini ante and post quem provided by u series dating for the beginning and end of the accumulation of the deposits the tl results corroborate that all radiocarbon dates below layer 11 are minimum ages only and given the constraints derived from the proxy data available place layer 13 and 14 post mis 5 sample as well as dosemeter numbers are low at gruta da oliveira which limits the precision of tl dating of a prehistoric human activity further refinement of the chronostratigraphy will be based on u series dating of non human related interstratified secondary carbonates

problems of the duration of the eemian interglacial in europe north of the alps abstract suggestions that the duration of the eemian interglacial was about 11 000 yr based on annually laminated sediment sequences in germany have been challenged in favor of a much longer interval however biostratigraphic evidence demonstrates why the eemian sequences at grande pile and ribains cannot be reliably used for alignment with the marine sequence as applied by kukla et al 2002 this issue to estimate the duration of this interglacial the long chronology they propose would imply not just coniferous but for up to 5000 yr fully temperate forest in central france coexisting with treeless heath and steppe tundra conditions in northwestern europe an unlikely climatic and ecological scenario the proposal that the eemian interglacial in western europe lasted for 17 000 or even 23 000 yr is rejected a duration of no more than 13 000 yr is preferred at least for sites north of the alps and pyrenees the duration of temperate conditions in the mediterranean region is less certain

revised tuning of ocean drilling program site 964 and kc01b mediterranean and implications for the δ18o tephra calcareous nannofossil and geomagnetic reversal chronologies of the past 1 1 myr 1 high resolution color reflectance records of kc01 and kc01b calabrian ridge ionian sea are presented and compared with a modified spliced high resolution color reflectance record of ocean drilling program odp site 964 this comparison revealed that kc01b is characterized by intensive deformation between 27 and 28 5 m piston depth and that some sapropels are tectonically reduced in thickness moreover the piston coring has caused considerable stretching in the top of kc01 and kc01b using a new splice of odp site 964 as guide previous astronomical tuned timescales of kc01b and odp site 964 were evaluated this evaluation resulted in a new sapropel based astronomical timescale for the last 1 1 myr the new timescale implies a much more uniform change in sedimentation rate for the ionian sea cores two prominent excursions to lighter values in the 18o record of the planktonic foraminiferal species globigerinoides ruber occur during marine isotopic stages 12 and 16 applying the new timescale these shifts correspond with maxima in obliquity and are punctuated by minima in the precession cycle they are absent in global ice volume records and are interpreted as reflecting a summer low salinity surface water lens that floats on top of extremely saline intermediate and deep waters at times of the very low sea levels during these glacial periods all biostratigraphic and magnetostratigraphic events found in kc01b and odp site 964 were re dated according to the new timescale and the ages of 33 tephra layers were reviewed the new ages for the calabrian ridge 2 and 3 magnetic events in the brunhes are concordant with minima in the global sint800 composite record derived from worldwide deep sea records of relative paleointensity and have been attributed to the big lost and la palma excursions respectively

characteristics of wind blown sand on gobi mobile sand surface the characteristics of wind blown sand on gobi mobile sand surface have been investigated through field observation and wind tunnel experiments on moving sand surface the pattern of wind speed profile in sand flow follows the power function overline u az b and its power exponent is about 0 20 while on gobi surface due to collision of sand grains with gravels the structure of sand flow differs from that on moving sand surface which decreases exponentially with height the height of blown sand activities on gobi surface is mainly concentrated below 20 cm in addition the structure of sand flow can reach a peak at a certain height and increases with inlet wind velocity

depositional environment and climate changes during the late pleistocene as recorded by the netiesos section in southern lithuania the netiesos section in southern lithuania exposes a late pleistocene sedimentary sequence at a depth of between 17 and 4 m an interdisciplinary study of the section investigated the environmental changes that occurred in the study area during the greater part of marine isotope stage mis 5 geochemical thermoluminescence palaeontological plant macro remain diatoms fishbones and magnetic susceptibility analyses were performed on numerous sediment samples chronological control of the sequence was provided by electron spin resonance esr infrared optically stimulated luminescence ir osl and conventional radiocarbon dating methods this interdisciplinary approach enabled the subdivision of the section into stratigraphic units reflecting environmental changes according to chronological data the development of the netiesos palaeolake began at the end of the medininkai saalian glaciation which is thought to correlate with mis 6 and continued up to the thermophilous deciduous forests phase of the subsequent last interglacial of mis 5 sediments of the final phase of the interglacial are missing as are the initial and final phases of the following early nemunas weichselian cooling mis 4 the palaeomagnetic blake event was recorded in the interglacial sediments one of the richest palaeofloras in the east baltic region was observed representing the second half of mis 5 the implications of the results for the regional late pleistocene climato chronostratigraphy are discussed

the blake magnetic polarity episode in cores from the mediterranean sea abstract palaeomagnetic and oxygen isotope studies on samples taken from five cores in the mediterranean area are described directions of the stable remanent magnetisation show the presence of an anomalous reversed zone during the transition between the oxygen isotope substages 5e and 5d this position corresponds to the age of about 117 kyr b p and thus to the blake polarity episode the duration of this episode is estimated to be about 6000 years the study of the anisotropy of the magnetic susceptibility shows no indication of sedimentological disturbances in recorded sections the blake episode therefore represents a stratigraphic marker which may be used to link the continental and marine palaeoclimatic and sedimentary records

controlling windblown sand problems by an artificial gravel surface a case study over the gobi surface of the mogao grottoes abstract in arid regions gravel surfaces are usually known for protecting the soil from wind erosion trapping the sand and dust carried by the wind thereby forming a sink of sediment however gravel surfaces with a suitable gravel size and coverage density can also act as the source of sediment under unsaturated wind flow a dynamically equilibrated gravel surface can be built to prevent potential windblown sand problems in the dunhuang mogao grottoes in northwestern china unlike previous studies that suggested constructing a high coverage 50 or more gravel surface on the gobi land on top of the mogao grottoes a much lower value of 30 is recommended this kind of artificial gravel surface can protect the underlying sand materials from wind erosion and trap the invading westerly windblown sand at the same time the deposited sand over the artificial gravel surface can be transported to the western megadunes by the easterly wind under the multidirectional wind regime the gravel surface can remain from sand burial over the long term