high resolution sequence stratigraphic analysis of late quaternary deposits of the changhua coastal plain in the frontal arc continent collision belt of central taiwan abstract detailed analysis of the sequence stratigraphy in 30 cores from the late quaternary deposits of the changhua coastal plain provides a 25 ka record of the depositional history of a region situated in the frontal arc continent collision belt of taiwan twenty five lithofacies and nine facies associations are recognized an alluvial plain was the dominant feature during a pronounced sea level fall at 25 20 ka ago between 20 and 10 ka alluvial fans were deposited along the western front of the pakua tableland during movement along the changhua fault and a local sag basin was produced no other deposits in the seaward area are recognized between 20 and 16 ka or in the landward area between 20 and 10 ka between 16 and 6 ka the changhua coastal plain experienced rising sea level and retrogradational deposition from 16 to 10 ka estuarine deposits lower transgressive systems tract were deposited and the base of these deposits defines the last glacial maximum lgm unconformity sequence boundary now preserved in four regions to the east of the plain from 10 to 6 ka shelf shoreface and lagoonal deposits upper transgressive systems tract were laid either on top of the estuarine deposits or directly on the lgm unconformity surface by about 7 6 ka sea level had reached its peak maximum flooding surface and shelf and marginal marine sediments covered most of the study area after 6 ka the highstand was dominated by progradation of offshore transition shoreface lagoonal tidal channel tidal flat and alluvial plain deposits one thousand year old fluvial deposits in incised channels are preserved in the central part of the changhua coastal plain since then fluvial channels shifted southward to the present day chuoshuei river the depositional patterns in this tectonically active area during the last interglacial period reflect the complex interplay between high frequency sea level fluctuations tectonics subsidence and uplift and autocyclic processes in the seaward area however fluctuations in sea level were clearly the dominant factor in controlling the nature of depositional facies

hydrogeomorphic influences on salt marsh sediment accumulation and accretion in two estuaries of the u s mid atlantic coast abstract salt marshes in two contrasting estuaries of the u s mid atlantic coast barnegat bay and delaware bay were investigated to identify relationships between rates of sedimentation and marsh estuarine geomorphic setting barnegat bay is a microtidal lagoon estuary with back barrier and mainland coastal marshes whereas delaware bay is a micro mesotidal coastal plain estuary with sediment rich estuarine marshes salt marshes of both estuaries are dominated by spartina alterniflora an analysis was performed to characterize marsh hypsometry and tidal flooding characteristics and a coring study was conducted to measure rates of mineral sediment accumulation organic matter accumulation and vertical accretion using 137 cs and 210 pb chronology at nine sites in both estuaries mineral sediment and organic matter accumulation rates were significantly higher in delaware bay marshes sediment mean and 1 2 57 2 03 kg m 2 year 1 organic 0 65 0 26 kg m 2 year 1 than in barnegat bay sediment 0 31 0 27 kg m 2 year 1 organic 0 29 0 08 kg m 2 year 1 as were rates of accretion delaware bay 0 79 0 06 cm year 1 barnegat bay 0 28 0 06 cm year 1 regression analysis indicated that marsh accretion rates were positively correlated with rates of sediment and organic accumulation but the upper limit of accretion was governed by sediment accumulation tidal flooding frequency and duration did not correlate with marsh accumulation or accretion rates in either estuary suggesting that hydroperiod is subordinate to sediment availability in governing rates on 50 100 year time scales if true natural and or human influences on suspended sediment production and transport in these estuaries has potential to impact marsh accretionary status and stability independent of sea level rise

marine derived 14c calibration and activity record for the past 50 000 years updated from the cariaco basin abstract an expanded cariaco basin 14c chronology is tied to 230th dated hulu cave speleothem records in order to provide detailed marine based 14c calibration for the past 50 000 years the revised high resolution cariaco 14c calibration record agrees well with data from 230th dated fossil corals back to 33 ka with continued agreement despite increased scatter back to 50 ka suggesting that the record provides accurate calibration back to the limits of radiocarbon dating the calibration data document highly elevated 14c during the glacial period carbon cycle box model simulations show that the majority of observed 14c change can be explained by increased 14c production however from 45 to 15 ka 14c remains anomalously high indicating that the distribution of radiocarbon between surface and deep ocean reservoirs was different than it is today additional observations of the magnitude spatial extent and timing of deep ocean 14c shifts are critical for a complete understanding of observed glacial 14c variability

holocene evolution of an estuarine coast and tidal wetlands modern facies distribution patterns extensive core data and chronostratigraphic cross sections provide a detailed history of holocene inundation within the delaware bay estuary and sedimentation in adjacent coastal environments flooding of the estuary occurred with rising sea level as the shoreline retreated northwest along a path determined by the pre transgression topography simultaneous migration of an estuarine turbidity maximum depocenter provided the bulk of fine sediments which form the coastal holocene section of the estuary prior to 10 ka the ancestral bay was predominantly a tidal river and the turbidity maximum depocenter was located southeast of the modern bay mouth by 10 ka lowlands adjacent to the ancestral channel of the delaware river were flooded forming localized tidal wetlands and the depocenter had initiated high rates of fine grained sedimentation near the present bay mouth at that time coastal holocene strata began to onlap the interfluve highlands by 8 ka the fine grained depocenter had migrated northwest along the main channel of the delaware river although the widened mouths of tributary valleys continued to be active sites of sediment accumulation following the passage of the fine grained depocenter coarse grained sediments accumulated along the coast in response to increased wind wave activity during the middle holocene portions of the estuarine coast began to resemble modern geomorphology and washover barrier sands and headland beach sandy gravels accumulated along the southwest shore the late holocene was characterized by erosional truncation and submergence of aggraded coastal lithofacies and by planation of remnant highland areas knowledge of the eroded holocene section is fragmentary at present continued sea level rise is accompanied by deposition of tidally transported muds in coastal environments and deposition of sandy sediments in some offshore regions an unconformity marks the base of the developing open estuarine sequence of coarse clastic lithofacies and denotes the end of coastal accumulations modeling of coastal lithofacies transitions identifies specific lithofacies complexes in the holocene stratigraphic section which were influential in the evolution of the coast development of the holocene section of the estuary coast involved both constructive or aggradational and destructive or erosional phases

luminescence chronology of the upper pleistocene loess record at kurtak in m iddle siberia abstract the loess palaeosol sequence of kurtak situated at the western bank of the upper yenisei in middle siberia represents one of the best developed middle and upper pleistocene sediment records in yenisei siberia more than 40 m thick loess and loess like sediments intercalated by at least four pedocomplexes are exposed at a steep erosional slope at the bank of the krasnoyarsk water reservoir infrared optically stimulated luminescence irsl and thermoluminescence tl dating techniques have been applied on 38 fine grain samples from the upper 23 m of the profile representing the penultimate and last interglacial glacial cycle the irsl and tl age estimates are in good agreement with the geological estimates up to the last interglacial soil horizon oxygen isotope substage ois 5e the luminescence ages show that the lowermost truncated palaeosol of kastanosjem type is likely to have formed during the penultimate interglacial upon subaerial deposits three weak reddish brown palaeosols intercalated by reworked loess like sediments correlate with early upper pleistocene interstadials ois5dion of a and a succession of humic horizons alternated by cryoturbation processes kurtak pedocomplex is linked with ois 3 thick loess deposits between the pedocomplexes show now significant age increase with depth indicating high accumulation rates at around 23 ka ois 2 and 60 ka ois 4

holocene depocenter migration and sediment accumulation in delaware bay a submerging marginal marine sedimentary basin abstract the holocene transgression of the delaware bay estuary and adjacent atlantic coast results from the combined effect of regional crustal subsidence and eustasy together the estuary and ocean coast constitute a small sedimentary basin whose principal depocenter has migrated with the transgression a millenial time series of isopach and paleogeographic reconstructions for the migrating depocenter outlines the basin wide pattern of sediment distribution and accumulation upland sediments entering the basin through the estuarine turbidity maximum accumulate in tidal wetland or open water sedimentary environments wind wave activity at the edge of the tidal wetlands erodes the aggraded holocene section and builds migrating washover barriers along the atlantic and estuary coasts of delaware the area of the upland environment decreases from 2 0 billion m 2 to 730 million m 2 during the transgression the area of the tidal wetland environment increases from 140 million to 270 million m 2 and due to the widening of the estuary the area of open water increases from 190 million to 1 21 billion m 2 gross uncorrected rates of sediment accumulation for the tidal wetlands decrease from 0 64 mm yr at 6 ka to 0 48 mm yr at 1 ka in the open water environments uncorrected rates decrease from 0 50 mm yr to 0 04 mm yr over the same period we also present data on total sediment volumes within the tidal wetland and open water environments at specific intervals during the holocene

new insights into the weichselian environment and climate of the east siberian arctic derived from fossil insects plants and mammals multidisciplinary study of a key section on the laptev sea coast bykovsky peninsula east lena delta in 1998 2001 provides the most complete record of middle and late weichselian environments in the east siberian arctic the 40 m high mamontovy khayata cliff is a typical ice complex section built of icy silts with a network of large syngenetic polygonal ice wedges and is richly fossiliferous in combination with pollen plant macrofossil and mammal fossils a sequence of ca 70 insect samples provides a new interpretation of the environment and climate of the area between ca 50 and 12 ka the large number of radiocarbon dates from the section together with an extensive 14c database on mammal bones allows chronological correlation of the various proxies the bykovsky record shows how climate change and the last glacial maximum in particular affected terrestrial organisms such as insects and large grazing mammals both during the presumed karginsky interstadial mis 3 and the sartanian glacial mis 2 the vegetation remained a mosaic arctic grassland with relatively high diversity of grasses and herbs and dominance of xeric habitats the tundra steppe type this biome was supported by a constantly very continental climate caused by low sea level and enormous extension of shelf land variations within the broad pattern were caused mainly by fluctuations in summer temperature related to global trends but overprinted by the effect of continentality no major changes in humidity were observed nor were advances of modern type forest or forest tundra recorded suggesting a major revision of the karginsky interstadial paradigm the changing subtypes of the tundra steppe environment were persistently favourable for mammalian grazers which inhabited the shelf lowlands throughout the studied period mammal population numbers were lowered during the lgm especially toward its end and then flourished in a short but impressive peak in the latest weichselian just before the collapse of the tundra steppe biome throughout mis 3 and mis 2 the climate remained very favourable for the aggradation of permafrost no events of regional permafrost degradation were observed in the continuous bykovsky sequence until the very end of the pleistocene

radiocarbon and mammoth bones what s in a date the radiocarbon dating method has developed into a reliable dating method for organic sample materials the latest calibration curve released enables numerical dating covering the complete dating range of the method however the category of fossil bones is the subject of discussion concerning validity of the dates in particular for the oldest part of the c 14 timescale this is a complex interplay of sample material integrity contamination issues and proper blanks in practice a safe upper limit for c 14 dates of bone material appears to be 45 000 bp 50 000 calbp c 2014 elsevier ltd and inqua all rights reserved

holocene survival of late pleistocene megafauna in china a critical review of the evidence late quaternary megafaunal extinction chronologies are poorly understood across eastern and southeast asia previous radiometric studies suggested that surprisingly many extinct late pleistocene large mammal species survived into the holocene in northern china bos primigenius coelodonta antiquitatis mammuthus primigenius and southern china ailuropoda baconi crocuta crocuta ultima megatapirus augustus stegodon orientalis sus cf xiaozhu indicating that chinese megafaunal extinctions may have been staggered across the late quaternary we critically re examined all radiometric evidence suggesting holocene survival of chinese late quaternary megafauna and conducted new dating of mammal material from reportedly holocene sites containing characteristically late pleistocene faunas evidence for holocene survival of any chinese late pleistocene megafaunal species is weak or untenable no previous radiometric dates used to support holocene megafaunal survival represent direct bone dates for species of interest and stratigraphic association between material yielding holocene dates and megafaunal remains is dubious at most sites concerns over accurate identification of faunal material further confuse claims for holocene survival of many species robust radiometric last occurrence dates for extinct chinese megafauna are all restricted to the late pleistocene similar to the timing of many other late quaternary megafaunal species extinctions elsewhere in eurasia and the americas c 2013 elsevier ltd all rights reserved

the loess record from the section at kurtak in middle siberia abstract loess loess like sediments and the intercalated palaeosols along the bluffs of the river yenisei provide a detailed upper pleistocene climate archive for the southern part of middle siberia the section at kurtak is one of the most detailed loess palaeosol sequences in middle siberia two major periods of sediment accumulation were recorded in the sequence the stratigraphically oldest one post dating the last interglacial palaeosol and pre dating the kurtak pedocomplex oxygen isotope stage ois 3 the younger one post dating the kurtak pedocomplex and predating the holocene soil three major phases of soil formation occurred during the upper pleistocene the kameny log pedocomplex ois 5e consists of at least two pedogenetic episodes a lower clayey chernozem forming during a more humid and warmer climate than today and an upper chernozem representing a drier climate than today the latter one including a well pronounced carbonate rich horizon the sukhoy log pedocomplex consists of a chernozem like palaeosol and two kastanozjems ois 5c a and the kurtak pedocomplex ois 3 with two chernozem like palaeosols and up to three humic rich layers additionally weakly developed gleyed horizons are considered to represent palaeohydrological groundwater high levels the results indicate a synchronous evolution of climate and environment change in both the more oceanic driven climate of west and central europe and middle siberia as evidenced by luminescence dating results

the early holocene milankovitch thermal maximum and humans adverse conditions for the denali complex of eastern beringia abstract calibration of 14c ages has forced the revision of paleoecological relationships with the milankovitch thermal maximum 10 000 9000 cal bp edwards and barker palaeogr palaeoclimatol palaeoecol 109 1994 127 in eastern beringia paleo geographic factors had dramatic consequences for humans many represented by the late pleistocene early holocene 13 000 7000 cal bp denali complex calibration of 71 radiocarbon ages associated with denali occupations indicates that the earliest precede both the milankovitch maximum and the spread of spruce in interior alaska by 2000 yr some denali occupations co occur with weakly developed forest soil horizons that reflect stabilized surfaces later capped by loess denali occupations peaked during the worldwide temperature decline between 8500 and 8000 cal bp the mesoglacial beget geology 11 1983 389 or the younger younger dryas fewer sites date to the milankovitch maximum and suggest an inverse relationship between warmer climate and human population

quaternary fluvial history of the delaware river new jersey and pennsylvania usa the effects of glaciation glacioisostasy and eustasy on a proglacial river system abstract fluvial glacial and estuarine deposits in the delaware valley record the response of the delaware river to glaciation sea level change and glacioisostasy during the quaternary incision following an early pleistocene glaciation created the present valley which is inset into a pliocene strath and fluvial plain middle and upper pleistocene and holocene deposits were laid down in this inset valley estuarine terraces in the lower valley and bayshore at 20 m probably marine isotope stage mis 11 8 m mis 5e and 3 m mis 5a or c and a fluvial deposit that correlates to offshore mis 3 marine deposits at 20 m are at elevations consistent with glacioisostatic models successive incisions during lowstands in the middle and late pleistocene lengthened deepened and narrowed the channel in the lower valley and shifted the channel westward in delaware bay during mis 2 glaciation from 25 to 18 ka the delaware was diverted to the hudson shelf valley by glacioisostatic tilting most glacial sediment was trapped in fluvial lacustrine valley fills north of the terminal moraine incision of the valley fill was accomplished during the early stage of rebound between 17 and 12 ka drainage to the delaware shelf was restored between 15 and 13 ka as the forebulge collapsed during incision multiple postglacial terraces formed where the valley was perpendicular to rebound contours and so was steepened and elevated northward and a single terrace formed where the valley paralleled the contours and there was no differential elevation or steepening about 65 of the original volume of mis 2 glacial sediment remains in the main valley and most of the eroded volume is in the channel in the lower valley beneath holocene estuarine fill little glacial sediment reached the delaware or hudson shelf overbank deposition on the lower postglacial terrace and modern floodplain spans the holocene the volume of holocene sediment in the estuary and bay yields a basinwide denudation rate of about 20 m my

a functional analysis of the lgm microblade assemblage in hokkaido northern japan a case study of kashiwadai 1 abstract topics currently debated in the northeastern asian prehistory include the emergence and spread of microblade technology during the last glacial maximum lgm on these issues hokkaido the northernmost japanese island provides one of the earliest evidences of microblade technology the present study reports results of functional analysis on the lgm microblade assemblage from the kashiwadai 1 site hokkaido and preliminary comparisons with other upper paleolithic up assemblages in japan results indicate that microblades may have been slotted into and served as lateral edges of composite points use wear traces on burins and burin spalls show a strong correlation with antler bone or ivory abi processing end scrapers were used chiefly for hide working a blade may have been employed for sawing or cutting hides and flesh furthermore the comparison suggests that developed abi polishes exclusively observed on burins and burin spalls highlight the lgm microblade assemblage and are rarely found from the other up assemblages until the appearance of the lgm microblade assemblages this implies that the technology and concept to shape abi implements with burins seem to have emerged coincidently with the earliest microblade technology and may not have had roots from previous up technologies in both of the southern paleo sakhalin hokkaido kurile peninsula and paleo honshu island besides the microlithization investigating sophisticated abi technologies will also illuminate the first appearance and spread of the lgm microblade technologies in northeast asia

the good the bad and the ugly evaluating the radiocarbon chronology of the middle and late upper paleolithic in the enisei river valley south central siberia abstract the 14 c record for the upper paleolithic in siberia has remained largely unevaluated and includes good bad and ugly dates too often researchers accept either all published dates or only those dates that tend to support proposed chronological hypotheses regardless of sample quality and association this article systematically evaluates all published 14 c dates including several newly obtained ams dates from middle and late upper paleolithic sites in the enisei river valley of south central siberia to establish a reliable chronology for the region and address the tempo of modern human dispersals in siberia during late pleistocene times the revised chronology indicates humans were present before and after the last glacial maximum but absent during this climatic event results also suggest that human population in the region may have increased during the oldest dryas

devising quality assurance procedures for assessment of legacy geochronological data relating to deglaciation of the last british irish ice sheet this contribution documents the process of assessing the quality of data within a compilation of legacy geochronological data relating to the last british irish ice sheet a task undertaken as part of a larger community based project britice chrono that aims to improve understanding of the ice sheet s deglacial evolution as accurate reconstructions depend on the quality of the available data some form of assessment is needed of the reliability and suitability of each given age s in our dataset we outline the background considerations that informed the quality assurance procedures devised given our specific research question we describe criteria that have been used to make an objective assessment of the likelihood that an age is influenced by the technique specific sources of geological uncertainty when these criteria were applied to an existing database of all geochronological data relating to the last british irish ice sheet they resulted in a significant reduction in data considered suitable for synthesis the assessed data set was used to test a bayesian approach to age modelling ice stream retreat and we outline our procedure that allows us to minimise the influence of potentially erroneous data and maximise the accuracy of the resultant age models

tidal wetland record of holocene sea level movements and climate history abstract paleontological geochemical and lithological indicators of former marine and nonmarine influence are correlated between 13 cores from a tidal wetland wolfe glade on the southeast coast of delaware bay twenty new radiocarbon dates are used to establish the chronostratigraphy of marsh facies sediment iron content weight loss on ignition and remains of plants diatoms and foraminifera known to tolerate specific tidal inundation cycles are used to describe cored facies originating from supratidal intertidal and subtidal salt marsh subenvironments pollen assemblages are used to infer local holocene climate fluctuations and to reconstruct paleoenvironments during marsh evolution the record of paleoclimatology suggests the atlantic chron was warm with variable humidity in the region whereas the subboreal was dominated by cool and humid conditions the subatlantic was warmer and initially dryer with a cool humid phase prior to about 1 ka returning to warmer humid conditions in the last several centuries local relative sea level movements are characterized by five rapid short term episodes when the rate of sea level rise accelerated relative to the rate of marsh aggradation these episodes are recorded by transgressive facies contacts at 5 3 0 2 ka 4 4 0 2 ka 3 25 0 2 ka and 1 8 0 2 ka sidereal years an earlier transgressive facies contact dated 6 9 0 2 ka is probably not the product of a true sea level movement sea level movements are recorded throughout the marsh as palustrine or high marsh peats or peaty overlain by lower intertidal or subtidal marine deposits several features suggest that these episodes are local relative transgressions produced by short term accelerations in the rate of sea level rise relative to marsh aggradation the contemporaneity and apparent suddenness of marine inundations the sequence of facies indicating marine drowning the presence of similar events in marshes elsewhere in delaware bay and the marsh wide extent of indicative facies transitions we propose that the rapid and frequent sea level movements observed in wolfe glade are the result of surges and relaxations in the gulf stream and associated spin up and partial collapse of the north atlantic gyre in response to winds generated by changes in the north atlantic atmospheric thermal gradient associated with holocene climate fluctuations

emergence of a microlithic complex in the transbaikal region of southern siberia abstract upper paleolithic stone artifact microlithization embodied a change in tool design and production that noticeably impacted northeast asian prehistory here we trace the process of microlithization in the transbaikal region of southern siberia using core reduction event trees and morphometric analysis of cores and their by products microtechnology emerges in the transbaikal in the middle upper paleolithic just prior to the last glacial maximum lgm in the form of highly variable microcores with small flakes and blades and possibly sporadic pressure flaking and slotted tools this variability indicates an experimental period in microlithic technology after a 2000 year gap in the occupational record a highly standardized microblade technological complex consisting of wedge shaped microblade cores pressure flaking microblades and slotted osseous tools appears in the transbaikal as a fully adopted system this evidence suggests that microtechnologies developed within the transbaikal just prior to and during the lgm underwent refinement outside of the region for roughly 2000 years then was brought into the region during the lgm with flintknappers as a fully adopted system

comments on graf journal of archaeological science 36 2009 the good the bad and the ugly evaluating the radiocarbon chronology of the middle and late upper paleolithic in the enisei river valley south central siberia abstract here i present a critical evaluation of the analysis conducted by graf graf k e 2009 the good the bad and the ugly evaluating the radiocarbon chronology of the middle and late upper paleolithic in the enisei river valley south central siberia journal of archaeological science 36 694 707 of the paleolithic radiocarbon 14c dataset for the upper paleolithic sites in the yenisei river basin of central siberia graf applied a rating system to the corpus of existing 14c data for the region and announced some new 14c dates the results obtained however are highly biased due to several factors including prejudice concerning the higher accuracy of the ams technique in 14c dating and that 14c dates from the same cultural component should overlap with plus minus two sigmas ambiguities with the subdivision of the lateglacial period artificially high sample selection criteria incomplete factual material and unjustifiable and misleading statements on the 14c dating of fossil bones and the issue of last glacial maximum human presence in siberia as a result the conclusions made by graf graf k e 2009 the good the bad and the ugly evaluating the radiocarbon chronology of the middle and late upper paleolithic in the enisei river valley south central siberia journal of archaeological science 36 694 707 are unconvincing new analysis is necessary in order to improve the quality of treatment of the original data for the upper paleolithic 14c chronology in the yenisei river basin

detailed architecture of a compound incised valley system and correlation with forced regressive wedges example of late quaternary tet and agly rivers western gulf of lions mediterranean sea france abstract quaternary incised valley systems are usually characterized by the preservation of a single valley fill attributed to the last post glacial period moreover there are very few cases of correlation between incised valley system developed on inner shelf and sedimentary units observed on the mid to outer shelf mainly forced regressive wedges the roussillon shelf in the western part of the gulf of lion is a particular example of preserved quaternary compound incised valley system also characterized by a direct correlation with the forced regressive lowstand wedges on the mid outer shelf high resolution seismic data and a borehole 60 m deep located on the beach barrier permit an accurate study of the geometry and lithology of the system six imbricated and more or less preserved incised valleys and valley fills are observed up to the inner to mid shelf the key surfaces associated to the incised valleys are correlated to the boundaries of the forced regressive wedges they are assumed to be reworked surfaces at the borehole location only few thin layers less than 1 m thick of coarse grain and or floating pebbles are observed and should correspond to preserved fluvial lowstand deposits reworked under marine influence the valley fills are mainly composed of estuarine muddy silts from ams 14c age dating it is inferred that the uppermost incised valley system is younger than 45 ky cal bp based on those observations the six preserved incised valley systems are assumed to be controlled by the last six 4th order sea level cycles 100 ky of the middle to late quaternary the paleo topography of the underlying plio quaternary deposits controls the compound incised valley system location the deep topography of the messinian erosionnal surface is a controlling factor at a lower degree the partial preservation of the successive valley fill is attributed not only to the differential subsidence but also to the lateral migration of each incision and to the hydrodynamic regime

radiocarbon dates microblades and late pleistocene human migrations in the transbaikal russia and the paleo sakhalin hokkaido kuril peninsula abstract we compare late pleistocene archaeological 14c databases from the transbaikal russia and the paleo sakhalin hokkaido kuril peninsula pshk to the appearance and disappearance of microblade technology for evidence of human migration in the transbaikal we identify as many as three events at 24 830 22 740 and 15 000 cal bp respectively on the pshk we see migration at 26 800 and likely again at 13 000 cal bp we offer an explanation for the last glacial maximum origin of northeast asian microblades that reconciles several major points of current competing theories the later migration signals in both areas are weaker and associated with terminal pleistocene bolling allerod younger dryas environmental changes at the beginning of the mesolithic period in the transbaikal and the incipient jomon period on pshk in the former the second migration event may have been repopulation of an empty or sparsely inhabited area in the latter it appears to be population replacement when microblades completely disappear from the peninsula without a reduction in the number of 14c dates

transgression of an estuarine channel and tidal flat complex the lower triassic of barles alpes de haute provence france the lower triassic succession of barles alpes de haute provence france comprises an unconformable quartz arenite sand body of 90m thickness the succession may be informally divided into i lower channellized cross bedded member overlain by ii an upper fining upward member the lower member comprises vertically stacked subtidal channel units separated into five major sand bodies by thin developments of fine grained channel margin and shoal deposits subtidal channel fill deposits are dominated by varying scales of cross bedding these scales vary systematically from the base to the top of the member with large scale planar sets dominating the lowest channel sand body sand body 1 medium scale planar and trough cross bedding characterizing sand bodies 2 4 the largest scale planar sets in the highest sand body sand body 5 this upward change in cross bedding scale is concomitant with a decrease in both the relief of major channel sand body erosion surfaces and the proportion of preserved interchannel shoal deposits the succeeding fining upward member comprises small scale tidal channel units overlain by channel shoal and tidal flat deposits tidal flat sequences are characterized by parallel laminated wave and current rippled sandstones separated by bioturbated fine grained siltstones and mudstones the vertical variation in facies of the lower triassic succession suggests two main periods of deposition the lower member is considered to preserve successively more seaward components of a transgressive estuarine complex the overlying upper member records the seaward progradation of tidal channel shoal and tidal flat environments the unconformity bounded nature of the lower member combined with its systematic variation in facies suggests it may represent an incised valley estuarine fill developed in response to an early triassic relative sea level fall and subsequent rise succeeding tidal channel and tidal flat deposits forming the upper fining upward member reflect a change in sediment supply and or rate of relative sea level rise comparable with a progradational shoreline it is unclear whether this final depositional episode represents a period of highstand progradation or a later lowstand shoreline system developed following a further period of relative sea level fall and rise

the paleolithic site of longwangchan in the middle yellow river china chronology paleoenvironment and implications the longwangchan paleolithic site situated on the yellow river terraces in the hukou area shaanxi province china was found in 2003e2004 and two areas localities 1 and 2 of the site were excavated in 2005e2008 abundant stone artifacts including microliths a grinding stone fragment and a shovel with some animal bones and shells were recovered from locality 1 in this study the cultural deposits from locality 1 were dated using radiocarbon and optical dating techniques and the sediment properties of the deposits were analyzed the results show that the age of the deposits ranges from 29 to 21 ka and most of them were deposited between 25 ka and 29 ka this indicates that corresponds to late marine isotope stage mis 3 and early mis 2 during the human occupation period the climate in this area became colder and drier sediments from beds where the grinding slab and the shovel were found were dated to w25 ka which is the oldest among the grinding stones found in china the microliths and the grinding stone are important evidence for an incipient socio economic process that eventually led to the regional transition from hunting foraging to farming

revising the archaeological record of the upper pleistocene arctic siberia human dispersal and adaptations in mis 3 and 2 abstract as the main external driver environmental changes largely predetermine human population distribution especially in the arctic where environmental conditions were often too extreme for human survival not that long ago the only evidence of human presence here was the berelekh site in the lower reaches of the indighirka river this landmark dates to 13 000 12 000 years ago but it was widely accepted as documentation of the earliest stage of human dispersal in the arctic new research discussed here shows that humans began colonizing the siberian arctic at least by the end of the early stage of mis 3 at around 45 000 years ago for now this earliest known stage of human occupation in the arctic regions is documented by the evidence of human hunting the archaeological record of continued human occupation is fragmentary nevertheless evidence exists for each significant phase including the last glacial maximum lgm siberian arctic human populations were likely supported by the local mammoth population which provided humans with food and raw material in the form of mammoth tusks processing of mammoth ivory is recognized widely as one of the most important peculiarities of the material culture of ancient humans in fact ivory tool manufacturing is one of the most important innovations of the upper palaeolithic in northern eurasia technology that allowed manufacturing of long ivory shafts long points and full size spears was critical in the tree less open landscapes of eurasian mammoth steppe belt these technological skills reach their greatest extent and development shortly before the last glacial maximum but are recognizable until the pleistocene holocene boundary across northern eurasia in all areas populated by mammoths and humans loss of this stable source of raw material due to the late pleistocene mammoth extinction may have provoked a shift in post lgm siberia to the beringian microblade tradition this paper reviews the most important archaeological findings made in arctic siberia over the last twenty years

radiocarbon calibration beyond 20 000 14c yr b p by means of planktonic foraminifera of the iberian margin we present a new set of 14c ages obtained by accelerator mass spectrometry ams on planktonic foraminifera from a deep sea core collected off the iberian margin md952042 this site at 37 n is distant from the high latitude zones where 14c reservoir age is large and variable many independent proxies alkenones magnetic susceptibility ice rafted debris foraminifera stable isotopes abundances of foraminifera pollen and dinoflagellates show abrupt changes correlative with dansgaard oeschger and heinrich events of the last glacial period the good stratigraphic agreement of all proxies from the fine to the coarse size fractions indicates that the foraminifera 14c ages are representative of the different sediment fractions to obtain reliable 14c ages of foraminifera beyond 20 000 14c yr b p we leached the shells prior to carbonate hydrolysis and subsequent analysis for a calendar age scale we matched the iberian margin u37k profile with that of greenland summit 18o both are proxies for temperature which in models varies synchronously in the two areas the match creates no spurious jumps in sedimentation rate and requires only a limited number of tie points except for ages older than 40 000 14c yr b p greenland s gisp2 and grip records yield similar calendars the 14c and imported calendar ages of the iberian margin record are then compared to data from lacustrine annual varves and from corals and speleothems dated by u th previously used to extend the calibration beyond 20 000 14c yr b p the new record follows a smooth pattern between 23 000 and 50 000 cal yr b p we find good agreement with the previous data sets between 23 000 and 31 000 cal yr b p in the interval between 33 000 and 41 000 cal yr b p for which previous records disagree by up to 5000 cal yr the iberian margin record closely follows the polynomial curve that was previously defined by an interpolation of the coral ages and runs between the lake suigetsu and the bahamian speleothem data sets

the role of the rocky mountains in the peopling of north america abstract this paper argues that the rocky mountains played a significantly more important role in the process of the peopling of the new world than archaeologists have traditionally recognized although first americans did not reach the rockies before they set foot in any other new world region they could not have regardless of their point of entry by clovis time evidence suggests that clovis people knew the rocky mountain landscape intimately archaeologists should have long anticipated this given the many resources the rocky mountains offer that adjacent albeit archaeologically better known regions such as the plains and some parts of the far west do not at least not as ubiquitously these include plentiful water in the form of streams lakes snowpack and glaciers high quality sources of obsidian chert quartzite and other knappable stone and a vertically oriented landscape that maximizes floral and faunal diversity within comparatively condensed space two other non economic characteristics likely contributed significantly to the appeal of the rocky mountains to some first americans the power and sanctity nearly all humans attribute to mountains and the seemingly little recognized fact that northeast asian upper paleolithic people who populated the new world during the terminal pleistocene occupied mountainous landscapes for some 45 000 years prior to their departure for many first americans mountains not the flat windswept tundra of siberian stereotypes had always been home evidence for the familiarity of clovis groups with the rocky mountain landscapes comes principally from three clovis caches anzick fenn and mahaffy all three caches are located in the rockies collectively contain artifacts made from ten of the highest quality stone raw materials available in the southern central and northern rockies and at least one of the caches accompanies the burial of a young child who appears to have been interred intentionally on a prominent and likely sacred landform in a mountain valley bringing the paper s argument full circle that same child s genetic profile shows a direct link to that of another youngster buried thousands of years earlier at the late glacial maximum mal ta site in the mountainous trans baikal region of siberia

accelerator radiocarbon dating at the molecular level molecular level 14c dating is the isolation of specific classes of molecules for their 14c dating by accelerator mass spectrometry ams complex matrices such as fossil bone are difficult to date due to their extreme chemical heterogeneity by isolating individual amino acids contaminants humates are removed and crystalline amino acids result bones with 0 1 0 2 n and collagenous compositions can be dated accurately because structural collagen is present contaminants are removable with xad resin bones with 0 1 n and non collagenous compositions yield dates hundreds to thousands of years too young because most of the preserved organic matter is exogenous accelerator 14c dates on collagenous and non collagenous bones are not comparable due to intrinsic dating inaccuracies ams 14c dating of amino acids demonstrated that 1 post 10 800 year ages for north american megafauna are due to sample contamination not holocene ages on extinct fauna 2 a clovis age 10 900 years was established for a human fossil from the anzick site montana 3 holocene ages cannot be established absolutely for many north american human fossils because the bones were non collagenous 4 accurate ages are attainable on vertebrate fossils as small as passerine birds from pacific island localities 5 well preserved bones are datable without their destruction by extracting protein with water at high temperatures and 6 stratigraphic anomalies to 45 000 years in european upper paleolithic rock shelters are recognizable by dating bone directly

radiocarbon calibration curve spanning 0 to 50 000 years bp based on paired 230 th 234 u 238 u and 14 c dates on pristine corals abstract radiocarbon dating is the most widely used dating technique in the world recent advances in accelerator mass spectrometry ams and sample preparation techniques have reduced the sample size requirements by a factor of 1000 and decreased the measurement time from weeks to minutes today it is estimated that more than 90 percent of all measurements made on accelerator mass spectrometers are for radiocarbon age dates the production of 14 c in the atmosphere varies through time due to changes in the earth s geomagnetic field intensity and in its concentration which is regulated by the carbon cycle as a result of these two variables a radiocarbon age is not equivalent to a calendar age four decades of joint research by the dendrochronology and radiocarbon communities have produced a radiocarbon calibration data set of remarkable precision and accuracy extending from the present to approximately 12 000 calendar years before present this paper presents high precision paired 230 th 234 u 238 u and 14 c age determinations on pristine coral samples that enable us to extend the radiocarbon calibration curve from 12 000 to 50 000 years before present we developed a statistical model to properly estimate sample age conversion from radiocarbon years to calendar years taking full account of combined errors in input ages and calibration uncertainties our radiocarbon calibration program is publicly accessible at http www radiocarbon ldeo columbia edu along with full documentation of the samples data and our statistical calibration model

antarctic ice sheet palaeo thinning rates from vertical transects of cosmogenic exposure ages abstract constraining antarctic ice sheet evolution provides a way to validate numerical ice sheet models that aid predictions of sea level rise in this paper we collate cosmogenic exposure ages from exposed nunataks in antarctica that have been used or have the potential to be used to constrain rates of thinning of the antarctic ice sheets since the last glacial maximum we undertake quality control of the data and adopt a bayesian approach to outlier detection past thinning rates are modelled by monte carlo linear regression analysis we present thinning rates from 23 sites across antarctica the resulting data set is the first antarctic wide collation of past ice sheet thinning rates and provides an empirical starting point for future model data comparisons palaeo thinning rates are spatially variable with high rates appearing to correlate to areas of contemporary rapid changes on centennial timescales past thinning rates are comparable to modern day observations implying that modern day thinning has the potential to persist for centuries in numerous parts of antarctica the onset of abrupt thinning from all sites post dates meltwater pulse 1a suggesting that its source region s are distal to areas where exposure age constraints on ice surface geometry exist

transgressive changes from tidal estuarine to marine embayment depositional systems the lower cretaceous woburn sands of southern england and comparison with holocene analogs the lower cretaceous woburn sands lower greensand group in southern england constitutes one of the most intensively studied tidal sandstone outcrops for sedimentological and reservoir analog studies most recent workers have interpreted the whole 30 60 m 100 200 ft thick succession around leighton buzzard as representing an ancient tide dominated estuary however unequivocal estuary characteristics are limited to the lowermost part about 15 20 m 50 66 ft we suggest that a significant portion of the woburn sands and most of the middle part was formed in a tide dominated marine embayment hence the vertical facies change from the lower to middle part of the woburn sands is interpreted as a change from 1 a narrow estuary to 2 a broad marine embayment the wash embayment in eastern england is a striking modern analog it receives most of its sediments and waters from marine sources and is largely filled with nondiluted seawater moreover the holocene transgressive history of the wash is remarkably similar to the transgressive evolution of the woburn sands early estuarine sequence models predict landward translation of facies zones along the valley thalweg during transgression but eventual facies translation in the strike direction has not been fully documented or discussed an embayment facies that is not commonly confined in the early incised valley can occur vertically between the estuarine valley fill and marine shelf deposits and is probably underrepresented in current models however this segment of the transgression comprising along strike bay expansion and the development of a broad marine embayment may be more important than previously thought

holocene environmental change in the inner severn estuary uk an example of the response of estuarine sedimentation to relative sea level change holocene sediments of the wetlands around the inner severn estuary uk demonstrate a consistent stratigraphy of a single woody peat layer up to at least 4 5 m thick capped with a grey silty cla

holocene environmental and parasequence development of the st jones estuary delaware usa foraminiferal proxies of natural climatic and anthropogenic change abstract the benthic foraminiferal record of marshes located along western delaware bay st jones estuary usa reflects the response of estuaries to sea level and paleoclimate change during the holocene system tracts are recognized and within them parasequences based on sedimentological and foraminiferal assemblages identification the parasequences defined by foraminiferal assemblages appear correlative with rapid holocene climate changes that are of worldwide significance 6000 5000 4200 3800 3500 2500 1200 1000 and 600 cal years bp following postglacial sea level rise modern subestuaries and marshes in the region began to develop between 6000 and 4000 years bp depending on their proximity to the mouth of delaware bay and coastal geomorphology initial sediments were fluvial in origin with freshwater marshes established around 4000 years bp the subsequent sea level transgression occurred sufficiently slowly that freshwater marshes alternated with salt marshes at the same sites to around 3000 years bp locally another two transgressions are identified at 1800 and 1000 years bp respectively marine influence increased in the estuaries until 600 years bp little ice age when regression occurred sea level began to rise again during the mid 19th century at the end of the little ice age when marshes became established the presence of a sand lens in the upper and middle estuary and the reduction in the number of tests in the top samples in cores from the same area also suggest an anthropogenic influence the estuary infill resulted in a sharp transgressive sequence represented by salt marsh foraminiferal assemblages in the upper part of the cores the increase in marsh foraminifera in both areas suggests an increase in marine influence that might be due to the transgression beginning at the end of the little ice age about 150 180 years ago coupled with anthropogenic straightening of the channel in 1913