mechanisms limiting the northward extent of the northern summer monsoons over north america asia and africa abstract mechanisms determining the poleward extent of summer monsoon convergence zones for north america asia and africa are examined in an intermediate atmospheric model coupled with a simple land model and a mixed layer ocean observations show that thermodynamical factors associated with the net heat flux into the atmospheric column provide favorable conditions for the monsoon convergence zone to extend farther poleward than actually occurs to understand the discrepancy a series of experiments are designed to test the importance of mechanisms previously examined in the south american case by the authors namely soil moisture ventilation and the interactive rodwell hoskins mechanism the latter refers to the interaction between baroclinic rossby wave dynamics and convective heating in north america experiments suggest that ventilation by both temperature and moisture advection is a leading effect the interactive rodwell hoskins mechanism tends to favor east coast rainfall and west coast dryne

determining the burial time of single grains of quartz using optically stimulated luminescence abstract in the optical dating of sediments it is usually assumed that the optically stimulated luminescence osl signal has been completely reset by light exposure prior to burial this assumption is often not valid one approach to testing and perhaps circumventing this assumption is to examine the apparent date of last exposure to daylight of individual sediment grains this paper reports on the application for the first time of 2 new measurement protocols to the estimation of the radiation dose received during burial for individual quartz grains from an aeolian deposit of known age 10 000 year old which is considered likely to have been completely reset by sunlight at deposition additive dose laboratory doses added to the burial dose before osl measurement and regenerative dose doses added after measurement of osl from burial dose single aliquot protocols are applied to 28 and 25 individual grains respectively each grain provides an independent estimate d e of the burial dose the average d e from the additive dose protocol 21 8 1 1 gy is in good agreement with the average from the regenerative dose protocol 23 8 1 0 gy both agree well with 1 13 multiple grain regenerative dose single aliquot measurements each on 1 mg sub samples of 23 9 0 3 gy 2 9 multiple grain additive dose single aliquot measurements also on 1 mg sub samples of 22 4 0 7 gy and 3 one previously published multiple aliquot additive dose estimate of 23 5 0 6 gy using 52 sub samples each of 5 mg the resulting optical ages are in good accord with 14 c and thermoluminescence age determinations the distribution of equivalent doses in the single grains is however unexpectedly large 23 of mean d e given the very likely complete resetting of the osl signal at deposition possible reasons are discussed and it is concluded that heterogeneity in beta dosimetry is the most likely explanation the single grain optical dating protocols reported here allow a detailed examination of the dose distribution in very small samples thus they should enable accurate dates to be obtained for sediments and soils that contain poorly bleached or mixed age components as well as deposits in which quartz grains are present in extremely low abundance

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

modeling pleistocene local climatic parameters using macrophysical climate modeling and the paleoecology of pleistocene megafauna application of macrophysical climate modeling to sites containing specimens with reliable radiocarbon dates of the extinct giant beaver castoroides ohioensis allows an examination and comparison of their climatic parameters and the establishment of a rudimentary climatic envelope for this extinct species two climatic parameters were examined for this study temperature and precipitation an analysis of eight sites with the giant beaver indicates that the species was cold tolerant and lived under colder january and july temperatures than exist at these sites today at five of the eight sites the model suggests there was a shift in seasonal precipitation from the greatest amount of precipitation taking place during the late summer fall in the pleistocene to spring early summer today

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

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

using τc to estimate magnitude for earthquake early warning and effects of near field terms 1 this paper analyzes strong motion records of 24 large earthquakes to investigate the relationship between c the period parameter of the first motion and moment magnitude the records of some of the large magnitude events very close to the source include large near field terms therefore if we include the data with large near field terms we may overestimate the final size of the magnitude we identified records with large near field terms and did not include these data in processing the records to compute c for each event our analysis shows that the value of c is between the earthquake corner period and the period determined by the record duration 0 if the magnitude is less than 6 c closely approximates the corner period whereas c for larger earthquakes depends on the rupture process and location of asperity c for large earthquakes provides a lower bound on the event magnitude and approaches the corner period if a longer record is used we also propose a method to classify the records with and without large near field terms if the peak displacement amplitude for the first 3 s pd3 exceeds 1 cm and c exceeds 2 s the record is more likely to include large near field terms for the purpose of quick onsite warnings stations observing large near field terms provide valuable information large near field terms can be observed only if the magnitude is large and the epicentral distance is small therefore if the displacement exceeds a threshold e g pd 0 5 cm the ground motion at the site would likely become very large this criterion will help to issue warnings to the blind zone which is the region where there is insufficient time to issue a warning before the strong shaking arrives

using borehole records to estimate magnitude for earthquake and tsunami early warning systems this paper presents a new application of the ground motion prediction equations gmpes to estimate the event magnitude for earthquake and tsunami early warning systems this technique incorporates borehole strong motion records along with surface recordings provided by kiban kyoshin network kik net stations we analyzed strong ground motion data from earthquakes with moment magnitude m ranging from 5 0 to 8 1 recorded by kik net stations provided by japan s national research institute for earth science and disaster prevention nied over the interval of 1998 to 2010 we used 2160 strong ground motion accelerograms with peak ground acceleration pga larger than 10 cm s2 recorded by borehole seismographs and 890 waveforms with pga larger than 80 cm s2 recorded by surface seismographs to derive gmpes for pga and peak ground velocity pgv in japan these gmpes are used as the basis for regional magnitude determination predicted magnitudes from pga values mpga and predicted magnitudes from pgv values mpgv were defined separately for borehole and surface recordings mpga and mpgv strongly correlate with the moment magnitude of the event provided that at least 20 records for each event are available the results show that mpgv from borehole data has the smallest standard deviation among the estimated magnitudes and provides an accurate early assessment of earthquake magnitude we demonstrate that incorporation of borehole strong ground motion records immediately available after the occurrence of large earthquakes significantly increases the accuracy of earthquake magnitude estimation and improves earthquake and tsunami early warning systems performance

radiocarbon dates on bones of extinct birds from hawaii abstract bones from a stratified sedimentary deposit in the puu naio cave site on maui hawaiian islands reveal the late holocene extinction of 19 species of birds the age of the sediment and associated fauna was determined by direct radiocarbon dating tandem particle accelerator mass spectrometer tams of amino acids extracted from bones weighing as little as 450 mg the 14c dates indicate that sediment has been accumulating in the lava tube for at least the last 7750 years a suitable time frame for testing the hypothesis that holocene extinction on islands began after human colonization despite growing evidence that a worldwide wave of extinctions coincided with human colonization of oceanic islands little radiometric data have been available to date the extinction of most small fossil vertebrates on islands the tams technique of dating purified collagen from the bones of small vertebrates could lead to vastly improved chronologies of extinction for oceanic islands where catastrophic mid to late holocene extinction is expected or known to have occurred chronologies derived from nonarcheological sites that show continuous sedimentation such as the puu naio cave deposit may also yield key evidence on the timing of earliest human settlement of oceania

regional response to drought during the formation and decline of preclassic maya societies abstract the earliest complex societies and a distinctive set of pan regional social political and economic institutions appeared in the southern maya lowlands during the preclassic period ca 1200 1100 cal bce cal 300 ce the timing of these cultural changes was variably influenced by local developments interaction with other regions of mesoamerica and climate change we present a high resolution radiocarbon chronology for the growth of the early polity of cahal pech belize one of the first permanent settlements in the southern maya lowlands we compare our results to a database containing over 1190 radiocarbon dates from cultural contexts reported from five major regions of the southern lowlands to interpret the expansion and decline of emerging complex social groups during the preclassic comparisons to paleoclimate proxy datasets suggest that fluctuating climate regimes may have promoted alternating integration and fragmentation of early hierarchically organized societies stable climatic conditions during the middle preclassic 1000 900 300 cal bce fostered the centralization of populations and the formation of large regional polities across the southern lowlands an extended drought at the end of the late preclassic cal 150 300 ce likely contributed to the decline of some major polities in the central peten but smaller sites located in productive environments were more resilient and persisted in to the classic period this research provides a framework for understanding the complex social and environmental factors that influenced localized adaptations to climate change and the episodic growth and decline of early complex societies in prehistory

isotope paleoecology of episodic mid to late holocene bison population expansions in the southern plains u s a abstract we used a xad purified ams radiocarbon method to date 62 bison specimens from different contexts on the very southern extent of the great plains of north america to produce a precise chronology of bison population expansions spanning the last 6000 years sixty one of these samples provide stable carbon and nitrogen isotope data indicating relative temperature and moisture conditions during intervals defined by the presence of bison within this time span this chronology indicates climatic conditions favorable to bison were present in the greater central texas area including the uplifted edwards plateau and extending to the coastal plain during periods from 5955 to 5815 3290 to 3130 2700 to 2150 and 650 to 530 cal bp however isotope results suggest climatic conditions differed for each period the earliest calf creek period was characterized by cool but dry conditions the later late archaic 1 2 periods were increasingly warmer and wetter and the latest toyah period was cooler and drier than the late archaic periods but warmer and wetter than calf creek both the calf creek and toyah periods had higher variability within these overall trends comparison with regional records suggests that these periods represent variation within generally cool dry climates human adaptive response to increased bison availability resulted in significant cultural changes across all four periods

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

obsidian characterization by laser ablation icp ms and its application to prehistoric trade in the mediterranean and the near east sources and distribution of obsidian within the aegean and anatolia for geological studies interest in mass spectrometry with an inductively coupled plasma as an ion source and its association with laser ablation as a sample introduction technique la icp ms has steadily increased during the past few years and is now being developed in other fields such as archaeology after a description of the analytical procedure and the calculation method we show the potential of this technique to characterize almost non destructively archaeological artefacts among the 70 elements that could be routinely analysed by la icp ms with detection limits below the ppm level we choose to determine the more critical ones in order to evaluate the geochemical models of the magmatic process major elements rare earths and some transition elements a detailed survey of cappadocian obsidian flows is given and includes the characterization of nine different sources evidence of complex trade activities is clearly shown by the obsidian tools found at different prehistoric sites from neolithic to bronze age levels in the mediterranean and the near east new results obtained on some archaeological sites located in turkey syria and cyprus are presented they show the importance of cappadocian sources in obsidian trade our results show that la icp ms allows a non destructive analysis of archaeological objects and that it combines the advantage of the different classical methods used to characterize obsidian sources mainly xrf and inaa with high sensitivity and rapidity thus la icp ms appears to be a very powerful analytical tool and at this time this technique is the only one which can non destructively determine such an important number of elements with such low detection limits

pre screening techniques for identification of samples suitable for radiocarbon dating of poorly preserved bones under certain environmental conditions post depositional diagenetic loss of bone collagen can severely reduce the number of bones from a particular archaeological site that are suitable for stable isotopic analysis or radiocarbon dating this study examined nearly 300 bones from 12 archaeological sites across southern england known to yield poor or variable preservation to try to identify one or more pre screening technique s that would indicate suitable collagen preservation for radiocarbon dating the most reliable method was shown to be the percent nitrogen n of whole bone powder which has an 84 chance of successfully predicting whether or not a bone will yield sufficient i e 1 weight collagen for dating

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

near surface attenuation and site effects from comparison of surface and deep borehole recordings abstract near surface attenuation and site effects are investigated using the seismograms of 17 local earthquakes recorded at depths of 0 0 3 1 5 2 5 and 2 9 km in the cajon pass borehole southern california the borehole penetrates 500 m of miocene sandstone and then crystalline granitic basement rock previous estimates of site response have been limited to shallower holes where the surface reflection interferes with the upgoing direct wave and the deepest sensor is not below the severe near surface effects in bedrock spectral ratios of the direct p and s waves for each earthquake between the different recording levels are well modeled with frequency independent q and amplification at the borehole q p 27 8 and q s 21 7 in the upper 2 9 km increasing from q p 26 and q s 15 in the upper 300 m to q p 133 and q s 47 between 1 5 and 3 km one event was also recorded at a surface granite site less than 1 5 km from the wellhead comparison of the 2 9 km recording with that at this granite site gives q p 50 and q s 23 the similarity of these values with those of previous studies at a wide range of sites suggests that q is very low in the near surface independent of rock type near surface amplification appears considerably more site dependent at the wellhead the amplifications at 1 hz of the direct p and s waves are 12 7 and 13 7 respectively these values include the free surface effect and are in reasonable agreement with the impedance contrast from the borehole logs at the granite site amplification of both p and s waves is less than four direct wave amplification at the wellhead is therefore at least three times that of the granite site the spectra of the direct and coda waves of the one earthquake recorded at both the wellhead and granite sites are compared with the corresponding 2 9 km recording coda wave amplification is in good agreement with the direct wave at the rock site but at the borehole the coda wave amplification factor overestimates the direct wave amplification by a factor of 3

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

magnitude determination using strong ground motion attenuation in earthquake early warning 1 we use 1661 strong motion accelerograms with peak ground acceleration pga larger than 80 gal 1 gal 1 0 cm s2 from 77 earthquakes recorded by the taiwan strong motion instrumentation program tsmip stations to derive a strong motion attenuation relationship this relationship can be used to dynamically define a mpga magnitude for earthquakes using earthquake locations determined by earthquake early warning process the mpga magnitude using this strong motion attenuation relationship corresponds well with mw given a sufficient number of pga readings mems micro electro mechanical systems acceleration sensor could be widely used for ground motion monitoring purposes thus we propose that once a large earthquake has begun that we might be able to use strong near field tens of kilometers pga values to quickly estimate the earthquake s magnitude which would improve earthquake early warning

principal component analysis of the summertime winds over the gulf of california a gulf surge index a principal component analysis of the summertime near surface quick scatterometer quikscat winds is used to identify the leading mode of synoptic scale variability of the low level flow along the gulf of california during the north american monsoon season a gulf surge mode emerges from this analysis as the leading eof with the corresponding principal component time series interpretable as an objective index for gulf surge occurrence this index is used as a reference time series for regression analysis and compositing meteorological fields of interest to explore the relationship between gulf surges and precipitation over the core and marginal regions of the monsoon as well as the manifestation of these transient events in the large scale circulation it is found that although seemingly mesoscale features confined over the gulf of california gulf surges are intimately linked to patterns of large scale variability of the eastern pacific itcz and greatly contribute to the definition of the northward extent of the monsoonal rains

ground motion attenuation source and site effects for the 26 september 2003 m 8 1 tokachi oki earthquake sequence abstract on 26 september 2003 a megathrust earthquake of m 8 1 occurred at the kurile trench northern japan we used accelerograms recorded on more than 300 k net stations ranging in distance from 40 to 500 km to determine source attenuation and site effects for the mainshock and four aftershocks with m 7 3 6 4 5 9 and 5 5 the analyses are based on linear regression applied to the fourier spectra data of each event the ground motion attenuation for all the events can be modeled using an assumed geometric spreading coefficient b 1 1 0 with an associated anelastic attenuation model given by an apparent q 135 f 0 76 by using dummy variables in the regression site amplifications relative to national earthquake hazard reduction program nehrp c sites are determined for d and e sites nonlinear site amplification was investigated for the m 8 1 data but was not significant in determining the overall amplification factors fourier spectra data were corrected to a reference near source distance and site condition hard rock the source spectrum for each event was compared to that of the theoretical brune model spectrum in order to compute seismic moment and stress drop seismic moments obtained in this manner agree with those of other studies stress drops range from 100 to 200 bars with no apparent dependence on magnitude the mainshock stress drop was 120 bars a similar value 100 bars was calculated for an interface aftershock events with the highest stress drops near 200 bars may have been in slab events

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

an automatic processing system for broadcasting earthquake alarms in japan most of the damage caused by large earthquakes is concentrated within areas less than about 100 km from the focal regions we have developed an earthquake alarm system that determines earthquake parameters within a few seconds of the p wave s arrival at the closest station and then transmits the earthquake information before the s wave arrival in areas of possible serious earthquake damage since an earthquake alarm system requires the determination of reliable earthquake parameters as quickly as possible it is unreasonable to wait until waveform data from numerous stations have been collected for analysis for this reason we have developed a novel method of determining the hypocentral location by using the arrival times for only a few stations as well as the lack of p wave arrivals at other stations at a given time the use of not yet arrived data makes it possible not only to determine reliable hypocenter parameters within a few seconds but also to detect erroneous arrival time readings and remove them automatically since the available waveform data increases with time the system was designed to redetermine earthquake parameters every second our method was deployed in a real time system starting in july 2002 the real time system locates 10 20 events per day which includes a few felt earthquakes occurring in and around japan it was shown from the waveform data for about 100 felt earthquakes that almost all the events except those far from the network could be located within a few seconds when most of seismic energy has not even arrived at some stations close by we recently started widespread broadcasting of earthquake information in real time by using a satellite transmission system

late quaternary chronology and extinction of north american giant short faced bears arctodus simus abstract eight new ams radiocarbon dates on giant short faced bears arctodus simus from the contiguous united states are reported and previously published dates from across north america are reviewed and discussed the dates deemed to be most reliable are on purified collagen samples and these serve as the basis for interpreting the late pleistocene chronology and extinction of the species the oldest acceptable radiocarbon date from the lower forty eight states is 34 080 480 bp from island ford cave virginia and the youngest is the previously reported 9630 60 bp date from bonner springs kansas an additional date of 10 921 50 bp on the same kansas specimen indicates a precision problem in the age of this individual regardless of this anomaly new ams dates of 10 800 11 000 bp on a simus confirm that it existed up to the pleistocene holocene transition and may have been one of the last megafaunal species to go extinct in north america further these dates solidify the co existence of these massive bears with humans of the clovis cultural complex

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

reassessing the chronology of the archaeological site of anzick found in 1968 the archaeological site of anzick montana contains the only known clovis burial here the partial remains of a male infant anzick 1 were found in association with a clovis assemblage of over 100 lithic and osseous artifacts all red stained with ochre the incomplete unstained cranium of an unassociated geologically younger individual anzick 2 was also recovered previous chronometric work has shown an age difference between anzick 1 and the clovis assemblage represented by dates from two antler rod samples this discrepancy has led to much speculation with some discounting anzick 1 as clovis to resolve this issue we present the results of a comprehensive radiocarbon dating program that utilized different pretreatment methods on osseous material from the site through this comparative approach we obtained a robust chronometric dataset that suggests that anzick 1 is temporally coeval with the dated antler rods this implies that the individual is indeed temporally associated with the clovis assemblage

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

la icp ms analysis of clovis period projectile points from the gault site abstract a key tenet of clovis period hunter gatherer mobility is the utilization of large ranges based on the appearance of exotic raw materials particularly chert in clovis assemblages the identification of the sources of chert in clovis period assemblages is problematic as it has relied on macroscopic properties macroscopic characteristics of chert can be highly variable in a single outcrop occur across very large areas and have correlates in unrelated and far removed contexts an instrumental geochemical approach was utilized that potentially offers advances in the capacity to link chert artifacts to their sources trace element data was recovered from 33 clovis period projectile points from the gault site 41bl323 using laser ablation inductively coupled plasma mass spectrometry la icp ms this data was compared to trace element data recovered from 224 primary geologic samples of chert from multiple primary sources across the edwards plateau in texas the clovis points were compared to the geologic sources using canonical discriminant analysis to establish group membership at three spatial scales macro regional greater than 500 km regional between 30 and 500 km and local between 1 and 30 km it was found at the macro regional scale that 21 of the 33 clovis points were to be geochemically similar to edwards plateau sources at the regional scale 15 of the 21 identified edwards plateau clovis points could be attributed to a particular source lastly only two clovis points could be identified to particular sources at the local scale

glaze and slip pigment analyses of pueblo iv period ceramics from east central arizona using time of flight laser ablation inductively coupled plasma mass spectrometry tof la icp ms this paper presents the results of glaze paint and slip analysis of 161 white mountain red ware ceramic samples ad 1275e1325 from east central arizona time of flight laser ablation inductively coupled plasma mass spectrometry tof la icp ms analysis is used 1 to establish viability of the technique for measuring chemical compositions of glazes and slips and 2 to establish a methodology for inferring this structured variability specifically delineating the presence of specific pigment mixtures or recipes used by prehistoric potters in the greater southwest these data bear on archaeological questions about craft production exchange technology and social organization 2006 elsevier ltd all rights reserved

direct dating of the oxygen isotope record of the last deglaciation by 14c accelerator mass spectrometry major trends of quaternary global climate are reflected in the continental ice volume changes which have been reconstructed by oxygen isotope analysis1 2 18o records from deep sea sediments show that the net glacial build up occurs relatively slowly3 but that the end of an ice age occurs quickly in less than 10 000 yr implying a nonlinear response4 5 to simple milankovitch theory6 the latter observation suggests that the cause of the most recent deglaciation was the maximum in summer calorific radiation at the upper latitudes of the northern hemisphere centred around 11 000 yr ago a view supported by early studies7 later work has produced conflicting dates the main source of confusion being problems with obtaining accurate and reliable dates here by using accelerator mass spectrometry we have measured 14c for various species of foraminifera to produce a reliable timescale for the oxygen isotope record our results show that at the end of the last ice age continental ice sheets began to melt more than 4 000 yr before the northern hemisphere maximum of summer calorific radiation

the timing of late pleistocene mammalian extinctions in north america more than 375 14c dates from 150 fossil sites in north america have been analyzed to evaluate the question of extinction of late pleistocene megafauna when critically evaluated no 14c ages for any extinct pleistocene genera are younger than 10 000 yr b p

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

abrupt wind regime changes in the north atlantic ocean during the past 30 000 60 000 years 1 the inputs of higher plants in blake outer ridge subtropical western north atlantic during marine isotope stage 3 mis3 have been recorded at high resolution by quantification of c23 c33 odd carbon numbered n alkanes and c20 c30 even carbon numbered n alkan 1 ols in sediment sections of ocean drilling program site 1060 the changes of these proxies at this open marine site are mainly related to eolian inputs their concentrations and fluxes exhibit major abrupt variations that are correlated with dansgaard oeschger d o patterns in greenland ice cores the ratios between interstadials and stadials range between 2 and 9 times the intense flux increases in the d o stadials are linked to strong enhancements of the westerly wind regime at these subtropical latitudes during stadials the observed variation was paralleled by changes in wind blown dust and the polar circulation index in greenland ice which is in agreement with previously hypothesized atmospheric teleconnections between northern and middle low latitudes of the northern hemisphere the close correspondence between sedimentary and ice core proxies is evidence that crossings of the glacial climate thresholds involved major reorganizations of the troposphere the observed large rise in higher plant biomarkers indicates that climate stabilization in the d o stadial conditions led to main increases in wind intensity

chipped stone artefacts source areas and provenance studies of the northern belize chert bearing zone previous studies of the northern belize chert bearing zone which was widely exploited by the ancient maya for the production of chipped stone artefacts have suggested that chert from different parts of this zone might be chemically distinct this hypothesis is tested with an expanded data base of neutron activation analyses of raw chert and chalcedony from throughout northern belize these data together with data from previous studies indicate that the chert bearing zone is one chemically homogenous source and that meaningful distinctions cannot be made between different areas of the zone a more specific lithic source hypothesis is that the black chipped chert and chalcedony artefacts found at coastal maya sites in northern belize may come from a localized source area exhibiting this unique visual characteristic however the analysis conclusively demonstrates that these artefacts fall within the range of chemical variation of other chert and chalcedony from northern belize further the study yields convincing evidence that the colouration of these black lithic artefacts is caused by a weathering phenomenon and hence is not indicative of a particular source location

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

erratum to severnaya zemlya arctic russia a nucleation area for kara sea ice sheets during the middle to late quaternary quaternary science reviews 25 21 22 2006 2894 2936 abstract quaternary glacial stratigraphy and relative sea level changes reveal at least four expansions of the kara sea ice sheet over the severnaya zemlya archipelago at 79 n in the russian arctic as indicated from tills interbedded with marine sediments exposed in stratigraphic superposition and from raised beach sequences that occur at altitudes up to 140 m a s l chronologic control is provided by ams 14c electron spin resonance green stimulated luminescence and aspartic acid geochronology major glaciations followed by deglaciation and marine inundation occurred during mis 10 9 mis 8 7 mis 6 5e and mis 5d 3 the mis 6 5e event associated with the high marine limit implies ice sheet thickness of 2000 m only 200 km from the deep arctic ocean consistent with published evidence of ice grounding at 1000 m water depth in the central arctic ocean till fabrics and glacial tectonics record repeated expansions of local ice caps exclusively suggesting wet based ice cap advance followed by cold based regional ice sheet expansion local ice caps over highland sites along the perimeter of the shallow kara sea including the byrranga mountains appear to have repeatedly fostered initiation of a large kara sea ice sheet with exception of the last glacial maximum mis 2 when kara sea ice did not impact severnaya zemlya and barely graced northernmost taymyr peninsula

fossil packrat middens and the tandem accelerator mass spectrometer analyses of well preserved plant remains from ancient packrat neotoma middens have yielded much information on the history of vegetation fauna and climate from the more arid portions of north america over the past 40 000 years1 2 in most of the modern deserts woodland or forest communities were present during the last glacial age the wisconsin radiocarbon dating of packrat midden assemblages from a single cave or from several nearby sites in a homogeneous local area can yield a detailed local vegetation chronology for many thousands of years from within 30 50 m on the rocky slopes in front of the dry rock shelters3 4 the development of radiocarbon dating using the tandem accelerator mass spectrometer tams allows direct dating of very small samples here we present 20 examples of tams radiocarbon dates on packrat midden materials to illustrate their usefulness in testing anomalous mixtures of species in ice age communities understanding the details of plant migrations and refining wisconsin and holocene time boundaries based on range changes of important plant species table 1 fig 1

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

an index of interannual precipitation variability in the core of the north american monsoon region abstract seasonal precipitation anomalies associated with the continental north american monsoon system are characterized using a land based dataset derived from in situ observations across the southwestern united states and northwestern mexico coherent regions of interannual continental precipitation variability are derived from principal component analysis after defining separate early and late summer monsoon seasons the gravest mode of late season interannual variability captures precipitation anomalies in the core of the continental monsoon domain a simple spatial average is developed as an index of this core variability the seasonal separation allows examination of persistence of precipitation anomalies as an indicator of practical late season predictability possible influences of large scale oceanic interannual fluctuations enso and pacific decadal oscillation pdo on core index precipitation anomalies are also considered the core precipitation index exhibits considerably more early to

the taphonomy of mammoth localities in southeastern wisconsin usa abstract four southeastern wisconsin mammoth localities located within a glacial landscape had well preserved remains found in inter morainal depressions filled with lacustrine clays covered with peat numerous radiocarbon ages dated the mammoths to the late pleistocene the taphonomic analysis focused on determining the agency or agencies involved in site formation and the agency or agencies involved in modification to the bones statistical approaches to bone orientation data underscored that water transport was not a factor in the formation of the bone beds nor was water movement a disturbance factor the bone modification profile of the overall assemblage was dominated by chemical weathering followed by other chemical and microbiological processes root etching was the most common biological modification and the most frequent modifications are involved with the microenvironments of the surface to burial substrate potentially cultural modification accounted for only a small portion of the cortical damage to the bones this general profile indicated an assemblage far more influenced by the immediate environment than by passing animals or people

the principal mode of interannual variability of the north american monsoon system nonseasonal behavior of the north american monsoon system nams during the summer months june september is investigated based on monthly mean satellite data and the national centers for environmental prediction national center for atmospheric research reanalyses for the period 1979 97 the leading principal component of the monthly mean precipitation over the domain 58 358n 808 1258w is used as a reference time series the associated variations in fields other than the rainfall are identified based on linear regression analysis the reference time series is highly correlated with summer rainfall averaged over this broadly defined nams domain and is therefore referred to as the spatially integrated precipitation index ipi it is also correlated with hurricane activity over the tropical and subtropical northeast pacific in its positive polarity the ipi is characterized by an intensification and northward expansion of the itcz toward the mexican coast with enhanced rainfall throughout mexico but particularly in the south and in a relative sense in the semiarid northwest it has a well defined sea level pressure and surface wind signature with negative sea level pressure anomalies to the northwest of the region of enhanced rainfall and westerly wind anomalies converging into the region from the west along 108 208n these features extend upward to the 500 hpa level and are overlaid by weak anomalies of opposing sign in the upper troposphere there are indications of an associated deep barotropic planetarywave signature over the united states but the geopotential anomalies are only weakly correlated with the ipi the ipi is only weakly correlated with summer rainfall over the southwestern united states with enso and with sst anomalies within the nams domain

in the footsteps of pliny tracing the sources of garamantian carnelian from fazzan south west libya abstract references in the ancient sources indicate that the libyan desert was a source of carbunculi semi precious red stones and gemstones variously interpreted as ruby garnet and spinel amongst others while gemstones are not attested in the geological strata of fazzan south west libya a range of silica based stones including chert chalcedony agate and carnelian are known to originate in this area linked to an early civilisation known as the garamantes it has been long proposed that the geochemical signature and the variations in the relative proportions of quartz moganite phases can be used to distinguish between groups of stones of different origin the proposed methodology was tested on a number of archaeological samples from the garamantian sites of jarma ancient garama and saniat jibril in fazzan fragments of chert carnelian and amazonite found at the two sites have been identified as raw materials associated with beadmaking trace elemental data obtained by la icp ms were combined with mineralogical data obtained by x ray powder diffraction and raman spectroscopy on the same samples and a group of reference samples the dataset has been compared with the available literature and data from other localities around the world to this purpose a preliminary database of silica based materials was established for provenance work based on the scarce data available in the literature the importation of these stones from eastern localities such as india may be ruled out the measured data on archaeological samples and debitage allow us to define a reliable reference group of parameters for materials from fazzan which are likely to be derived from a unique geological source the methodology should be extended and compared with cherts and carnelians from a range of mediterranean and sub saharan sites this characterisation work is a tool of high potential utility for a new investigation of ancient contact and trade across the trans saharan zone

modulation of eastern north pacific hurricanes by the madden julian oscillation abstract hurricane and tropical storm statistics verify the modulation of eastern pacific tropical systems by the madden julian oscillation mjo as hypothesized by maloney and hartmann over twice as many named tropical systems hurricanes and tropical storms accompany equatorial 850 mb westerly anomalies than accompany equatorial easterly anomalies and the systems that do exist are stronger hurricanes are over four times more numerous during westerly phases of the mjo than during easterly phases the current study constructs a composite life cycle of the mjo during may november 1979 95 using an index based on the 850 mb equatorial zonal wind equatorial kelvin waves propagating eastward from convective regions of the western pacific ocean alter dynamical conditions over the eastern pacific ocean westerly easterly equatorial 850 mb wind anomalies are accompanied by enhanced suppressed convection over the eastern pacific hurricane region convection locally amplifies the wind anomalies over the ea

astronomical forcing of contrasting rainfall changes in tropical south america between 12 400 and 8800 cal yr b p abstract today precipitation over tropical south america is largely controlled by the seasonal movements of the inter tropical convergence zone itcz during the summer the itcz is shifted southward due to the warming of the continent paleoclimate data from southeastern amazonia and the central andes indicate that these two areas evolved similarly during the last 30 000 yr however between 12 400 and 8800 cal yr b p eastern amazonia received substantial moisture whereas the bolivian altiplano was arid this suggests that the itcz during summer was then farther north than it is today

intraseasonal variability associated with wet monsoons in southeast arizona the intraseasonal evolution of the north american monsoon in southeast arizona during the 1980 93 period is investigated using a neural network based nonlinear classification technique known as the self organizing map som the goal of the som algorithm is to discover meaningful low dimensional structures hidden in the high dimensional observations various daily lagged atmospheric fields 850 hpa meridional winds 700 hpa specific humidity 500 hpa geopotential heights and 850 500 hpa thickness for the summer season june july august september of the 1980 93 period are used in the nonlinear classification of monsoon modes special emphasis is given to the wettest monsoon modes the neural network classification successfully captures the multidimensional interaction of the atmospheric variables during the monsoon evolution and shows monsoon bursts and breaks in a given year spectral analysis of daily summer rainfall in the study area reveals a significant peak in the 12 18 day band a secondary and significant peak is also found near 40 days thus monsoon bursts and breaks seem to be modulated by low frequency variability the som nonlinear classification shows that the mature phase of the monsoon is associated with two distinct intraseasonal 10 days wet monsoon modes the signature of the wettest monsoon mode is a zonal three cell anomalous midtropospheric height pattern over the north pacific north american sector suggesting a largescale dynamical mechanism possibly linked to sea surface temperature sst anomalies in the north pacific this zonal mode which is most frequent in july and august is characterized by an enhanced and northeastwarddisplaced monsoon ridge large amounts of midtropospheric moisture over the study area and an out of phase relationship between precipitation in the southwest united states and precipitation in the great plains the zonal mode has been recognized in longer datasets and it is the most typical mode that characterizes the mature phase of the monsoon in the southwest united states in contrast the second wettest intraseasonal monsoon mode does not show a monsoon ridge but a meridional three cell anomalous midtropospheric height pattern along the west coast of north america weak height anomalies over the rest of north america and large amounts of moisture over the study area importantly this meridional mode which is most frequent in august and september does not show out of phase links to great plains precipitation the meridional wet mode also shows an anomalous low level cyclonic circulation off the west coast of central south mexico suggesting that convective activity off the southern mexican coast possibly associated with the intertropical convergence zone may cross over the isthmus of tehuantepec toward the gulf of mexico and the southern united states this would explain the weak link between precipitation in the southwest and precipitation in the great plains during august and september of the 1980 93 period at more regional scales the zonal wet mode is also characterized by a latitudinal gradient of sst anomalies between baja california and southern mexico and reversed low level flow over the gulf of california looking at extreme wet monsoons outside of the study period e g 1955 1959 1999 it is shown that the positive sst anomaly pattern along the pacific coast of baja california which characterized wet events during 1980 93 can be completely reversed during other extreme wet events these contrasting results suggest that interaction between local and remote forcing mechanisms over the study area are complex during extreme events and needs further investigation

early human remains from bano nuevo 1 cave central patagonian andes chile abstract the notable sparseness of human skeletal remains is a characteristic trait of early american prehistory and therefore this aspect of the archaeological record is seldom considered in its discussion in this context the finding of remains from five individuals dated to the 9th millenium bp on the re excavations at bano nuevo cave andean central patagonia chile is particularly interesting they may not appear excessively old but several radiocarbon dates two of them done through ams directly on the bone of one of the individuals place them among the very few well dated early human skeletons throughout the americas the small sample size militates against any interpretation of biological affiliation to say nothing of population movements and we can only affirm that these people belonged to a generalized mongoloid stock different from historically known patagonian populations after a brief presentation of the skeletal evidence and the bone dating methods we evaluate the relevance of this context with respect to the sparse osteological record of humans in the americas on the pleistocene holocene transition

magnitude estimation using the first three seconds p wave amplitude in earthquake early warning 1 pd is the peak amplitude of displacement in the first three seconds after the arrival of the p wave we investigated the attenuation of pd with the hypocentral distance r in southern california as a function of magnitude m and obtained the following relationship log pd 3 463 0 729 m 1 374 log r 0 305 given an earthquake location determined by the p wave arrival times at stations close to the epicenter this relationship can be used to define a so called pd magnitude of earthquakes our result shows that for earthquakes in southern california the pd magnitudes agree with the catalog magnitudes with a standard deviation of 0 18 for events less than magnitude 6 5 therefore pd is a robust measurement for estimating the magnitudes of earthquakes and has practical application in earthquake early warning systems citation wu y m and l zhao 2006 magnitude estimation using the first three seconds p wave amplitude in earthquake early warning geophys res lett 33 l16312 doi 10 1029 2006gl026871

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

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

maintenance of summer monsoon circulations a planetary scale perspective abstract the monsoon circulation which is generally considered to be driven by the landmass ocean thermal contrast like a gigantic land sea breeze circulation exhibits a phase reversal in its vertical structure a monsoon high aloft over a continental thermal low is juxtaposed with a midoceanic trough underlaid by an oceanic anticyclone this classic monsoon circulation model is well matched by the monsoon circulation depicted with the observational data prior to the first global atmospheric research program garp global experiment fgge however synthesizing findings of the global circulation portrayed with the post fgge data it was found that some basic features of major monsoon circulations in asia north america south america and australia differ from those of the classic monsoon circulation model therefore a revision of the classic monsoon theory is suggested with four different wave regimes selected to fit the horizontal dimensions of these monsoon circulations basic features common to

holocene age of the yuha burial direct radiocarbon determinations by accelerator mass spectrometry the view that human populations may not have arrived in the western hemisphere before about 12 000 radiocarbon yr bp1 2 has been challenged by claims of much greater antiquity for a small number of archaeological sites and human skeleton samples one such site is the homo sapiens sapiens cairn burial excavated in 1971 from the yuha desert imperial county california3 5 radiocarbon analysis of caliche coating one of the bones of the skeleton yielded a radiocarbon age of 21 500 1 000 yr bp4 while radiocarbon and uranium series analyses of caliche coating a cairn boulder yielded ages of 22 125 400 and 19 000 3 000 yr bp respectively5 the late pleistocene age assignment to the yuha burial has been challenged by comparing the cultural context of the burial with other cairn burials in the same region6 on the basis of the site s geomorphological context and from radiocarbon analyses of soil caliches 7 8 in rebuttal arguments in defence of the original age assignment have been presented9 10 as well as an amino acid racemization analysis on the yuha skeleton indicating an age of 23 600 2 600 yr bp11 the tandem accelerator mass spectrometer at the university of arizona has now been used to measure the ratio of 14c 13c in several organic and inorganic fractions of post cranial bone from the yuha h sapiens sapiens skeleton isotope ratios from six chemical fractions all yielded radiocarbon ages for the skeleton of less than 4 000 yr bp these results indicate that the yuha skeleton is of holocene age in agreement with the cultural context of the burial and in disagreement with the previously assigned pleistocene age of 19 000 23 000 yr

post clovis survival of american mastodon in the southern great lakes region of north america abstract the end of the pleistocene in north america was marked by a wave of extinctions of large mammals with the last known appearances of many species falling between ca 11 000 10 000 14c yr bp temporally this period overlaps with the clovis paleoindian cultural complex 11 190 10 530 14c yr bp and with sudden climatic changes that define the beginning of the younger dryas chronozone ca 11 000 10 000 14c yr bp both of which have been considered as potential proximal causes of this extinction event radiocarbon dating of enamel and filtered bone collagen from an extinct american mastodon mammut americanum from northern indiana usa by accelerator mass spectrometer yielded direct dates of 10 055 40 14c yr bp and 10 032 40 14c yr bp indicating that the animal survived beyond the clovis time period and into the late younger dryas although the late survival of this species in mid continental north america does not remove either humans or climatic change as contributing causes for the late pleistocene extinctions neither clovis hunters nor the climatic perturbations initiating the younger dryas chronozone were immediately responsible for driving mastodons to extinction

survey of 2011 tohoku earthquake tsunami inundation and run up 1 at 14 46 local time on march 11 2011 a magnitude 9 0 earthquake occurred off the coast of northeast japan this earthquake generated a tsunami that struck japan as well as various locations around the pacific ocean with the participation of researchers from throughout japan joint research groups conducted a tsunami survey along a 2000 km stretch of the japanese coast more than 5300 locations have been surveyed to date generating the largest tsunami survey dataset in the world on the sendai plain the maximum inundation height was 19 5 m and the tsunami bore propagated more than 5 km inland along the ria coast from about 50 to 200 km north of sendai the narrow bays focused the tsunami waves generating the largest inundation heights and run ups the survey data clearly show a regional dependence of tsunami characteristics

high precision ams 14c chronology for gatecliff shelter nevada abstract gatecliff shelter provides a deeply stratified record of human environment interaction in the desert west spanning most of the middle and late holocene the well preserved 10 m deep deposits serve as an important reference sequence for technological and subsistence change in the great basin archaeological work started at gatecliff in 1970 and a geochronological framework was established based on 47 uncalibrated radiocarbon 14 c dates obtained from several conventional radiometric laboratories between 1972 and 1982 these radiocarbon dates are not well accommodated within a bayesian chronological model for these important deposits due to multiple temporal reversals and large analytical errors this model was discarded in favor of one based on a combination of high precision ams 14 c dates of short lived carbonized plant remains supplemented with existing 14 c dates culled from the original set using a bayesian chronological model summed probabilities of the modeled posterior distributions of these 14 c dates n 24 show episodic use of the shelter as a logistic hunting camp between 6050 and 3315 cal bp a significant hiatus in occupation between 3315 and 2145 cal bp and more persistent use by family bands after this time in the future this high precision chronology will provide the foundation for reinterpreting broader patterns of technological and subsistence change in the intermountain west and evaluating these changes relative to high resolution climate records

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

man and megafauna in tasmania closing the gap abstract recent discussion on the late pleistocene extinction of the australian megafauna has revolved around interpretation of several key fossil sites in tasmania it has been suggested that humans did not arrive in tasmania until after the megafauna became extinct or did not hunt now extinct megafauna and therefore that humans cannot be implicated in the extinctions radiocarbon results from these sites indicate that the youngest extinct megafauna are close to charcoal ages from the oldest archaeological deposits although difficulties have arisen in establishing chronologies because most relevant sites have ages near the limit for radiocarbon analysis we report a series of new radiocarbon ages 13 c 15 n and c n ratios on collagen and dentine fractions from skeletal remains in the mount cripps karst area and the mowbray swamp both in northwestern tasmania and discuss the reliability of ages from these and other sites we also report the discovery of an articulated simosthenurus occidentalis skeleton at mt cripps that represents only the second directly dated extinct megafaunal taxon with a reliable age our results suggest that c n ratios measured on collagen or dentine are not an infallible guide to radiocarbon age reliability we confirm previous reports of a temporal overlap between the megafaunal and archaeological records in tasmania but the presence of archaeological evidence and megafauna with the same age at the same site has not yet been demonstrated at least two megafaunal taxa the now extinct protemnodon anak and a giant pleistocene form of the extant macropus giganteus were still present in tasmania after 43 ka when human crossing of the bassian landbridge from mainland australia first became sustainable

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

accelerator dating of a mixed assemblage of late pleistocene insect fossils from the lamb spring site colorado abstract fossil insects from the late glacial deposits at the lamb spring archaeological site near denver colorado are relatively abundant and diverse providing considerable paleoecological data for the site the late pleistocene insect fauna from the site comprises 72 identified taxa principally beetles however the fauna presented an interpretive problem because it contained a mixture of prairie and alpine tundra species this was initially considered to be the result of a mixing of faunal elements during the climatic transition of late glacial times a no modern analog fauna accelerator dating of insect fossil specimens from the two ecological groups helped resolve the paleoecological problem fossil specimens of the prairie associated species were dated at 17 850 550 yr b p while specimens of the tundra associated species yielded an age of 14 500 500 yr b p these dates reveal that what appeared to be an ecological mixing was probably a taphonomic problem wherein full glacial age fossils were probably reworked into latest wisconsin sediments while both faunal assemblages reflect climatic conditions substantially colder than present initial results suggest that the full glacial fauna represents a cold dry grassland or steppe environment while the younger fauna suggests moister and more tundra like conditions

updating martin s global extinction model australia has been cited as a weak link in anthropogenic models of megafauna extinction but recent work suggests instead that the evidence for rapid extinction shortly after human arrival is robust the global model is revisited based on the contention that late pleistocene megafauna extinctions took place rapidly on islands and some islands such as australia and the americas are much larger than others modern dating methods are increasingly able to refine chronologies and careful scrutiny suggests that hundreds of dates should be deleted from archives an updated summary of results from new zealand north america and australia is presented with a brief discussion on why temperate refugia offering protection from climate change ultimately did not work strongly supporting the global extinction hypothesis pioneered by paul martin

the quartzite problem revisited abstract a review of past terminology and previous petrological studies suggests that quartzite should be classified descriptively as both a sedimentary and a metamorphic rock quartzite is identified in the field as a quartz rich rock exclusive of chert and vein quartz that is exceptionally hard and when broken by a rock hammer fractures irregularly through both grains and cement where present to form an irregular or conchoidal fracture surface quartzite is differentiated from quartzose sandstone arenite which is softer and fractures around individual grains and from chert and vein quartz by a bright vitreous luster quartzite is classified further on the basis of microscopic features into orthoquartzite and metaquartzite by the presence of clastic and metamorphic microtextures respectively low grade medium grade and high grade subtypes of metaquartzite are differentiated by mortar foam and porphyroblastic microtextures respectively composition is not used as a criterion for classifica

a geoarchaeological evaluation of a reported late pleistocene human burial from brazoria county texas the skeleton of a human adult female was excavated from alluvial sediments along the gulf coastal plain of texas she was buried face down in an extended position with her hands crossed beneath the waist initial radiocarbon ages indicated that this skeleton dated to the late pleistocene geoarchaeological and archaeological excavations at the site coupled with new radiocarbon ages amino acid compositional data and an analysis of the previously reported radiocarbon ages obtained from the skeleton instead suggest a middle holocene age for this burial

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

a window into the complexity of the dynamic rupture of the 2011 mw 9 tohoku oki earthquake the 2011 mw 9 tohoku oki earthquake recorded by over 1000 near field stations and multiple large aperture arrays is by far the best recorded earthquake in the history of seismology and provides unique opportunities to address fundamental issues in earthquake source dynamics here we conduct a high resolution array analysis based on recordings from the usarray and the european network the mutually consistent results from both arrays reveal rupture complexity with unprecedented resolution involving phases of diverse rupture speed and intermittent high frequency bursts within slow speed phases which suggests spatially heterogeneous material properties the earthquake initially propagates down dip with a slow initiation phase followed by sustained propagation at speeds of 3 km s the rupture then slows down to 1 5 km s for 60 seconds a rich sequence of bursts is generated along the down dip rim of this slow and roughly circular rupture front before the end of the slow phase an extremely fast rupture front detaches at about 5 km s towards the north finally a rupture front propagates towards the south running at about 2 5 km s for over 100 km key features of the rupture process are confirmed by the strong motion data recorded by k net and kik net the energetic high frequency radiation episodes within a slow rupture phase suggests a patchy image of the brittle ductile transition zone composed of discrete brittle asperities within a ductile matrix the high frequency is generated mainly at the down dip edge of the principal slip regions constrained by geodesy suggesting a variation along dip of the mechanical properties of the mega thrust fault or their spatial heterogeneity that affects rise time

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

la icp ms analysis of quartzite from the upper gunnison basin colorado we report the results of la icp ms analysis of 402 quartzite samples representing 48 collection loci in the upper gunnison basin ugb colorado and determine the extent to which the sources can be geochemically discriminated from one another using this non destructive technique the ability to differentiate among the sources would open the door to provenance studies of the quartzite chipped stone tools and debitage that constitute 95 or more of most of the 3000 plus prehistoric site assemblages documented in the ugb our samples represent prehistorically quarried and non quarried quartzite sources including outcrop primary and gravel secondary deposits the results reveal spatial and chronological trends in quartzite elemental composition that can be exploited for provenance determinations of quartzite artifacts from ugb sites albeit using an assemblage based sourcing strategy that differs from the familiar approach of matching obsidian artifacts to their statistically likeliest geological source we offer a preliminary version of a sourcing protocol for ugb quartzite

patterns of diagenesis in bone ii effects of acetic acid treatment and the removal of diagenetic co32 abstract archaeological bones of varying preservation have been treated with 0 1 m acetic acid in order to investigate the effect on structural and chemical alterations caused by diagenesis acetic acid is commonly used as a cleaning agent for removing diagenetic carbonate from bone and enamel in an attempt to recover original biogenic signals for use in dietary and14c dating studies diagenetic parameters were measured before and after treatment on a range of archaeological bones with good and bad preservation histological preservation defined the behaviour of the correlating parameters where correlation coefficients between carbonate content and crystallinity microporosity and macroporosity increased significantly after treatment for histologically well preserved material acetic acid is effective at returning carbonate content to around that of modern bone where bone is extensively damaged by micro organisms loose diagenetic material can be removed but a fraction largely composed of hypermineralized bioapatite remains which we believe cannot be reliably used to obtain accurate biological signals

the effects of dental wear on impairing mammoth taxonomy a reappraisal of the newton mammoth bradford county northeastern pennsylvania a mammoth skeleton found at the newton site a kettle lake 15 km southeast of towanda pennsylvania has been referred to mammuthus columbi on the basis of its high narrow skull however the specimen s thin enamel 1 3 1 8 mm and moderately high lamellar frequency 8 8 75 lophs dm resemble some specimens of mammuthus primigenius prehistoric range maps show that a columbian mammoth inhabiting the towanda area would be a significant outlier from this species range however its location would align well with the range of m primigenius to better ascertain the newton mammoth s identification we examine herein the effects of dental wear on the morphology of mammoth molars as mammoth molars wear the enamel lophs become more broadly spaced and the enamel ridges thicken towards the base of the crown thus an older m primigenius with extensively worn molars might display thicker enamel and a lower lamellar frequency and might therefore appear to be a columbian mammoth on the basis of dental morphology alone our results show that the molars of the newton mammoth are well worn and are characterized by an enamel thickness and lamellar frequency that aligns better with m primigenius than with m columbi we conclude that one must take into account the effects of dental wear when classifying mammoth species using solely molars

magnitude estimation for the 2011 tohoku oki earthquake based on ground motion prediction equations this study investigates whether real time strong ground motion data from seismic stations could have been used to provide an accurate estimate of the magnitude of the 2011 tohoku oki earthquake in japan ultimately such an estimate could be used as input data for a tsunami forecast and would lead to more robust earthquake and tsunami early warning we collected the strong motion accelerograms recorded by borehole and free field surface kiban kyoshin network stations that registered this mega thrust earthquake in order to perform an off line test to estimate the magnitude based on ground motion prediction equations gmpes gmpes for peak ground acceleration and peak ground velocity pgv from a previous study by eshaghi et al in the bulletin of the seismological society of america 103 2013 derived using events with moment magnitude m 5 0 1998 2010 were used to estimate the magnitude of this event we developed new gmpes using a more complete database 1998 2011 which added only 1 year but approximately twice as much data to the initial catalog including important large events to improve the determination of attenuation parameters and magnitude scaling these new gmpes were used to estimate the magnitude of the tohoku oki event the estimates obtained were compared with real time magnitude estimates provided by the existing earthquake early warning system in japan unlike the current operational magnitude estimation methods our method did not saturate and can provide robust estimates of moment magnitude within 100 s after earthquake onset for both catalogs it was found that correcting for average shear wave velocity in the uppermost 30 m v text s 30 improved the accuracy of magnitude estimates from surface recordings particularly for magnitude estimates of pgv mpgv the new gmpes also were used to estimate the magnitude of all earthquakes in the new catalog with at least 20 records results show that the magnitude estimate from pgv values using borehole recordings had the smallest standard deviation among the estimated magnitudes and produced more stable and robust magnitude estimates this suggests that incorporating borehole strong ground motion records immediately available after the occurrence of large earthquakes can provide robust and accurate magnitude estimation

the midsummer drought over mexico and central america abstract the annual cycle of precipitation over the southern part of mexico and central america exhibits a bimodal distribution with maxima during june and september october and a relative minimum during july and august known as the midsummer drought msd the msd is not associated with the meridional migration of the intertropical convergence zone itcz and its double crossing over central america but rather with fluctuations in the intensity and location of the eastern pacific itcz during the transition from intense to weak weak to intense convective activity the trade winds over the caribbean strengthen weaken such acceleration in the trade winds is part of the dynamic response of the low level atmosphere to the magnitude of the convective forcing in the itcz the intensification of the trade winds during july and august and the orographic forcing of the mountains over most of central america result in maximum precipitation along the caribbean coast and minimum precipitation along the pacific

carbonate deposition pyramid lake subbasin nevada 2 lake levels and polar jet stream positions reconstructed from radiocarbon ages and elevations of carbonates tufas deposited in the lahontan basin most of the tufas in the pyramid lake subbasin were deposited within the last 35 000 yr including most of the mound tufas that border the existing lake many of the older tufas 21 000 yr b p contained in the mounds were formed in association with ground water discharge the radiocarbon 14c ages of the older tufas represent maximum estimates of the time of their formation lake lahontan experienced large and abrupt rises in level at 22 000 15 000 and 11 000 yr b p and three abrupt recessions in level at 16 000 13 600 and 10 000 yr b p the lake level rises that were initiated at 23 500 and 15 500 yr b p are believed to indicate the passage of the polar jet stream over the lahontan basin during expansion of the laurentide ice sheet the jet stream moved south across the basin and during the contraction of the ice sheet the jet stream moved north across the basin the bulk of the carbonate contained in the mound tufas was deposited during the last major lake cycle 23 500 12 000 yr b p indicating that ground and surface water discharges increased at 23 500 and decreased at 12 000 yr b p a lake level oscillation that occurred between 11 000 and 10 000 yr b p is represented by a 2 cm thick layer of dense laminated tufa that occurs at and below 1180 m in the low elevation tufa mounds and at 1205 m in the winnemucca lake subbasin

severnaya zemlya arctic russia a nucleation area for kara sea ice sheets during the middle to late quaternary quaternary glacial stratigraphy and relative sea level changes reveal at least four expansions of the kara sea ice sheet over the severnaya zemlya archipelago at 79 degrees n in the russian arctic as indicated from tills interbedded with marine sediments exposed in stratigraphic superposition and from raised beach sequences that occur at altitudes up to 140 m a s l chronologic control is provided by ams c 14 electron spin resonance green stimulated luminescence and aspartic acid geochronology major glaciations followed by deglaciation and marine inundation occurred during mis 10 9 mis 8 7 mis 6 5e and mis 5d 3 the mis 6 5e event associated with the high marine limit implies ice sheet thickness of 2000m only 200km from the deep arctic ocean consistent with published evidence of ice grounding at similar to 1000m water depth in the central arctic ocean till fabrics and glacial tectonics record repeated expansions of local ice caps exclusively suggesting wet based ice cap advance followed by cold based regional ice sheet expansion local ice caps over highland sites along the perimeter of the shallow kara sea including the byrranga mountains appear to have repeatedly fostered initiation of a large kara sea ice sheet with exception of the last glacial maximum mis 2 when kara sea ice did not impact severnaya zemlya and barely graced northernmost taymyr peninsula