holocene sea level change and the emergence of neolithic seafaring in the fuzhou basin fujian china abstract neolithic seafaring across the taiwan strait began approximately 5000 years ago and involved open sea voyages over distances of at least 130 km rapid sea level rise preceded the emergence of open sea voyaging but the possible role of environmental change as a stimulus for the development of seafaring is poorly understood we investigate this problem by presenting a record of holocene sea level change and coastal transformation based on sediment cores obtained from the fuzhou basin on the coast of fujian china the cores are located in direct proximity to archaeological sites of the tanshishan neolithic culture 5000 4300 cal bp which is significant for its similarity to the earliest neolithic cultures of taiwan multiple lines of evidence record the early holocene inundation of the fuzhou basin around 9000 cal bp the mid holocene sea level highstand and the final holocene marine transgression this final transition is precisely documented with ams dates showing the change occurred close to 1900 cal bp our paleogeographic reconstruction shows that a large estuary filled the fuzhou basin during the mid holocene tanshishan and zhuangbianshan two of the major fuzhou basin neolithic sites are located today on hills nearly 80 km from the modern coastline however when the sites were settled around 5500 5000 cal bp the marine transgression had transformed these hills into islands in the upper estuary we suggest that the neolithic era estuary setting together with the lack of land suitable for rice paddy agriculture inhibited intensive food production but favored a maritime orientation and the development of seafaring

ocean atmosphere forcing of centennial hydroclimate variability in the pacific northwest reconstructing centennial timescale hydroclimate variability during the late holocene is critically important for understanding large scale patterns of drought and their relationship with climate dynamics we present sediment oxygen isotope records spanning the last two millennia from 10 lakes as well as climate model simulations indicating that the little ice age was dry relative to the medieval climate anomaly in much of the pacific northwest of north america this pattern is consistent with observed associations between the el nino southern oscillation enso the northern annular mode and drought as well as with proxy based reconstructions of pacific and atlantic ocean atmosphere variations over the past 1000 years the large amplitude of centennial variability indicated by the lake data suggests that regional hydroclimate is characterized by longer term shifts in enso like dynamics and that an improved understanding of the centennial timescale relationship between external forcing and drought is necessary for projecting future hydroclimatic conditions in western north america

lateglacial and holocene hydroclimate inferred from a groundwater flow through lake northern rocky mountains usa climate driven variations in lake groundwater exchange are recorded by sediments in groundwater dominated lakes a groundwater flow through lake in west central montana usa registers latest pleis

worldwide initiation of holocene marine deltas by deceleration of sea level rise radiocarbon dated deltaic sequences of holocene age from different parts of the world began to accumulate within a restricted time range from about 8500 to 6500 years ago evaluation of major delta processes indicates that deceleration in sea level rise was the key factor in holocene delta formation within many deltas there is as much as a 2000 year age range between basal deposits in seaward and landward cores this age difference records the progressive landward migration of near mean sea level depositional environments during the lower to mid holocene establishment of a chronostratigraphic framework for holocene delta development provides a fundamental global baseline for distinguishing sea level change from vertical land motion by tectonism and isostasy and for evaluating rates of future marine incursion into low lying deltas

taihu lake lower yangtze drainage basin evolution sedimentation rate and the sea level abstract the present study focuses on two holocene sediment boreholes in taihu lake sunk to examine the lake sediment including sedimentary texture and structure microfossils magnetic susceptibility and radiocarbon dated holocene stratigraphy results demonstrate that the early taihu lake area consisted primarily of west taihu lake depression and a low floodplain in the east taihu lake area no hydraulic connection existed between the two sectors during the early holocene when sea level stood at lower level core sediments microfossil and magnetic evidence records that west taihu lake began to be inundated by brackish water prior to 6000 years ago while east taihu lake still remained a freshwater setting after 6000 b p a further rise in freshwater table in response to sea level fluctuation progressively drowned the entire lake coalescing the two parts after 4600 3500 b p our coring revealed that the lacustrine sediment began to form in west taihu lake as early as 11 000 years ago while it happened much later only after 5700 b p to form in east taihu lake high sedimentation rates 0 42 0 35 mm year in lacustrine deposits of west taihu lake occurred between 11 000 and 5000 b p in contrast the high sedimentation rates 1 54 mm year in east taihu lake occurred only within a very short time period from 6500 to 5500 b p since then sedimentation rates have decelerated to a very low value

morphodynamic characteristics of the dextral diversion of the yangtze river mouth china tidal and the coriolis force controls this paper examines the morphological development of the yangtze river mouth which has been diverting southeasterly dextrally according to historical 150 years chart based digital evolution model and on site measured tidal flow data we reveal a significantly narrowing of the northern river mouth branch from formerly 30 km wide to presently 10 km wide due to rapid siltation net siltation there however decreases gradually which largely contrasts with the fact that the siltation has shifted to the southern river mouth area as shown by many newly emerged estuarine islands sandy shoals and bifurcated branches our data have further demonstrated that the ebb flow that dominates in the study area changes its direction gradually from east to southeast from the inner to outer river mouth area and its duration is much longer than the flood flow in the inner river mouth area but nearly equal at the river mouth area accordingly the sediment transport pathway has been diverted from east to southeast we examine whether the coriolis force could explain the dextral diversion of the ebb flow and the altered morphodynamical processes although too weak to strengthen the tidal flows the coriolis force can drag the ebb flow southeasterly and so influence sediment transport paths at the estuarine scale the coriolis force is limited in the inner river mouth but substantial at and in the outer river mouth area when gradually free of estuarine topographic constraints the coriolis force causes an offset in propagation of in out flow directions at the river mouth area to form a slack water setting prone to estuarine siltation using the present approach also enables explanation of the morphological development of the holocene yangtze delta coast that extends to the southeast copyright 2010 john wiley sons ltd

sedimentary facies of the tide dominated paleo changjiang yangtze estuary during the last transgression abstract a large estuary was formed by marine inundation of the paleo changjiang yangtze incised valley during the transgression after the last glacial maximum this paper presents the sedimentary facies and architecture of the estuary fill based on the analysis of three sediment cores cm97 js98 and hq98 obtained from the present changjiang delta plain estuary fill deposits showing an upward fining succession were grouped into five depositional facies tidal river distributary channel muddy intertidal to subtidal flats transgressive lag and estuary front based on sedimentary textures lithology and physical sedimentary structures sand mud couplets are common in these deposits indicating that tides played a significant role in producing these sedimentary structures and that the estuary type was tide dominated some of the successive sand mud couplets probably recorded neap spring cycles as well as semidiurnal tidal cycles the nature of the estuary was very different from other representative tide dominated estuaries in sediment facies its distribution and sediment source for estuarine fill unlike the other estuaries that receive sediments mainly from the sea the paleo changjiang estuarine fill deposits were supplied largely from the river this difference would also have a great influence on the sedimentological and morphological component in the estuary the sediment distribution of the estuary showed fining seaward and estuary mouth sand bodies fed by marine source sand were absent the architecture model of tide dominated estuaries should be divided into two types by the degree of fluvial sediment supply the paleo changjiang estuary shows a good example for an estuary of large rivers

pollen and non pollen palynomorph analyses of upper holocene sediments from dianshan yangtze coastal lowlands china hydrology vegetation history and human activity abstract the coastal deltaic plain of the yangtze river between taihu lake tai and shanghai in eastern china has been the scene of human settlement and agriculture since the early neolithic becoming increasingly intensive in the upper holocene when delta accretion and the establishment of a stable hydrological regime of freshwater lakes and wetlands allowed the development of extensive agriculture and complex society in late prehistoric and dynastic times during this period the area was significantly affected by changes in sea level climate and vegetation resulting in a dynamic and complex environmental history however little research has concentrated on environmental change and human impacts during the last few millennia this study focuses on this late period presenting the results of integrated sedimentary microfossil and radiocarbon analyses from a core near the eastern margin of lake dianshan to the east of taihu after the withdrawal of intertidal conditions and the conversion to freshwater lake at the core site about 2600 cal yr bp pollen and algal spore data show that increased sedimentation gradually reduced freshwater depth until a surface peat formed ca 1500 cal yr bp this also dates the start of a switch in woodlands from sub tropical and warm temperate trees to a mainly cool temperate and coniferous tree flora under climatic cooling and human impact after this time water depths at the site increased greatly partly due to climate change and flooding but also because of the establishment of deepwater paddy agriculture microcharcoal and pollen data show that a major episode of human impact using fire with deforestation and rice cultivation occurred between ca 1500 and 1200 cal yr bp these dates suggest it is one of the latest examples of flooded field paddy cultivation before more intensive agricultural techniques were adopted in the area after ca 800 cal yr bp

polyphase reactivation history of the towaliga fault central georgia implications regarding the amalgamation and breakup of pangea abstractthe towaliga fault southern appalachians contains fault rocks that formed under various p t conditions revealing a complex reactivation history it trends 070 along the northwest flank of the pine mountain window changes to 035 at the northeast end of the window and continues northeastward into the inner piedmont isolated kilometer scale rhomboidal pods of silicified cataclasite along the towaliga fault likely represent ancient dilational step overs which acted as conduits for hydrothermal fluid flow during faulting and consequently are sites of concentrated mineralization towaliga fault garnet grade mylonite formed during large displacement alleghanian 295 ma dextral strike slip while geometric and kinematic evidence suggests dilational step overs formed in a small displacement sinistral strike slip system mutually overprinting crosscutting relationships with mesozoic diabase dikes confirm cataclasis occurred 200 ma silicified dilational step overs are present along both fault o

yangtze delta eastern china 2 late quaternary subsidence and deformation abstract late quaternary deposits examined on high resolution seismic profiles provide evidence of recent subsidence of the outer yangtze delta in the east china sea deformed late pleistocene strata and mud diapirs tilted bedding and gas deformed structures in holocene sequences record remobilization of underconsolidated sediment within and adjacent to the yangtze depocenter deformation types and their specific position relative to the depocenter record displacement of sediment as a result of quaternary overburden and probable compaction and deep seated tectonic motion the configuration of depositional sequences demonstrates that subsidence in the outer yangtze delta has continued from the late pleistocene to the present

stratigraphy and paleoenvironmental changes in the yangtze delta during the late quaternary the yangtze delta area may be subdivided into paleo valley and paleointerfluves of the last glaciation the postglacial transgressive sedimentary cycle ptsc on the front zones of the paleointerfluves is composed of marsh nearshore and barrier lagoon shallow marine and nearshore tidal flat units with a basement in stiff clay the ptsc in back zones of the paleointerfluves consists of lacustrine marsh deposits the ptsc in the incised valley contains river channel floodplain estuary estuarine shallow marine and deltaic units with an erosional surface at its bottom the stiff clay and the erosional surface constitute the ptsc lower boundary the stiff clay consisting of a paleosol experienced deposition alternating with pedogenesis during the falling of sea level during 18o stage 3 ongoing pedogenesis in the sea level lowstand of 18o stage 2 and early diagenesis after paleointerfluve inundation by the sea level rise of 18o stage 1 the climate during the paleosol formation was temperate with more than 500 mm a 1 rainfall and frequently fluctuating groundwater the yangtze river incised its course during falling sea level of stage 3 and a huge incised valley was formed during the sea level lowstand stage 2 the filling of the incised valley took place during the postglacial sea level rise and delta formation occurred at a late stage of ptsc development

cheniers in china an overview abstract in various regions along the east and southeast coast of china and on the outer shelf of the east china sea series of cheniers have been found and studied their geomorphological and sedimentological features have been described and the main conditions for their formation established the development of cheniers in china can be divided into three periods 24 000 15 000 yrs b p 7000 5000 yrs b p and 5000 yrs b p onwards these periods have been based on 14c datings of 80 shell samples the chenier groups of the three periods are distributed throughout various geomorphological locations using the geomorphological locations of the cheniers in combination with their age of formation the palaeopositions of the chinese coastline in the various periods since 24 000 yrs b p are described the history of the position of the east coast of china including the features attesting to sealevel changes during this era is briefly discussed

mid to late holocene geomorphological and hydrological changes in the south taihu area of the yangtze delta plain china abstract the taihu plain of the lower yangtze valley china was a centre of rice agriculture during the neolithic period reasons for the rapid development of rice cultivation during this period however have not been fully understood for this coastal lowland which is highly sensitive to sea level change to improve understanding of the geomorphological and hydrological context for evolution of prehistoric rice agriculture two sediment cores dtx4 and dtx10 in the east tiaoxi river plain south taihu plain were collected and analysed for radiocarbon dating diatoms organic carbon and nitrogen stable isotopes 13c and 15n grain size and lithology these multiproxy analyses revealed that prior to ca 7500 cal yr bp the east tiaoxi river plain was a rapidly aggrading high salinity estuary the palaeo taihu estuary after ca 7500 cal yr bp low salinity conditions prevailed as a result of strong yangtze freshwater discharge subsequently seawater penetration occurred and saltmarsh developed between ca 7000 and 6500 cal yr bp due to accelerated relative sea level rise this transgression event influenced a large area of the taihu plain during the holocene as shown by multiple sediment records from previous studies persistent freshwater marsh or subaerial land formed due to dramatic shrinkage closure of the palaeo taihu estuary after ca 5600 cal yr bp when sea level was relatively stable we speculate that geomorphological and hydrological changes of the east tiaoxi river plain played an important role in agricultural development across the taihu plain during the neolithic period the closure of the palaeo taihu estuary and the formation of stable freshwater marsh or subaerial land after ca 5600 cal yr bp were critical preconditions encouraging the rapid rise of rice productivity in the liangzhu period 5500 4500 cal yr bp this development changed the landscape and river systems and thus provided adequate freshwater supply to the taihu plain

sediment dispersal along northern israel coast during the early holocene geological and archaeological evidence abstract combined geological and archaeological study of finds at atlit yam a pre pottery neolithic settlement submerged off the carmel coast of northern israel provides new information on sediment provenance and dispersal in the southern levant clay mineral analyses of mud rich samples collected in a water well ca 8100 7550 yrs b p at this site are useful for determining the early holocene circulation pattern along this margin analyses record the predominance of fluvial sediment from proximal carmel highland sources to the east as indicated by illite and of marine sediment from the north and northeast as indicated by kaolinite this north to south coastal transport is in marked contrast to the present south to north dispersal pattern where smectite rich nile material is derived from distal sources and carried hundreds of kilometers to the carmel margin the interpreted coastal circulation pattern indicates that although the modern nile delta major source of sediment in the eastern mediterranean had begun to form about 8000 7500 yrs ago it had not yet begun to supply substantial amounts of sediment to as far north as the carmel coast by the time the water well was abandoned the atlit yam site serves as a unique geochronologic gauge valuable for interpreting climatic oceanographic and sedimentologic conditions in the se mediterranean which as recently as 7500 yrs ago were markedly different than those prevailing at present

persistent positive north atlantic oscillation mode dominated the medieval climate anomaly the medieval climate anomaly mca was the most recent pre industrial era warm interval of european climate yet its driving mechanisms remain uncertain we present here a 947 year long multidecadal north atlantic oscillation nao reconstruction and find a persistent positive nao during the mca supplementary reconstructions based on climate model results and proxy data indicate a clear shift to weaker nao conditions into the little ice age lia globally distributed proxy data suggest that this nao shift is one aspect of a global mca lia climate transition that probably was coupled to prevailing la nina like conditions amplified by an intensified atlantic meridional overturning circulation during the mca

spatiotemporal variability of the precipitation dipole transition zone in the western united states 1 el nino southern oscillation related hydroclimatic variability in the western united states is characterized by a north south dipole pattern of precipitation anomalies with opposing signs here i use a high resolution dataset to analyze spatiotemporal patterns in the transition zone between the centers of opposite association results indicate that the transition zone is spatially limited west of the continental divide consisting of a narrow zone within the 40 42 n latitude band and portions of eastern washington eastern oregon and western colorado the transition zone was narrower when the southern oscillation index and the pacific decadal oscillation pdo were in a constructive phase and during the negative atlantic multidecadal oscillation phase although the transition zone has remained remarkably stationary across the great basin shifts likely pdo related have occurred over time in the west coast states implications for water resource planning in river basins underlying the transition zone vary by region

neolithic settlement distributions as a function of sea level controlled topography in the yangtze delta china combined geological and archaeological data sets indicate that sea level controlled topography best explains the timing of neolithic settlement onto the southern yangtze delta plain almost 1500 yr later than inland china information on settlement patterns of the three major neolithic cultures ma jia bang song ze liang zhu dated from ca 5500 to 2200 b c is provided by petrologic study of habitat bases of sites and of sediment cores recovered near the sites in the early holocene rising sea level induced decreased relief and an aggrading silt mantle on the low lying delta surface changes of sea level and climate from early to mid holocene initiated a fertile delta plain at ca 6000 5500 b c and settlement and cultivation including rice began within only 500 yr of delta formation rate of sea level rise decelerated by mid holocene time resulting in rising ground water level and poor drainage and a reduced delta plain area suitable for human occupation and agriculture as a consequence neolithic settlements shifted progressively eastward toward higher more restricted areas of the yangtze delta chenier plain

migration of neolithic settlements in the dongting lake area of the middle yangtze river basin china lake level and monsoon climate responses the vast dongting lake in the middle yangtze river basin china was occupied by chinese neolithic settlements starting 10 000 years ago and rice cultivation there is probably the earliest in the world the numerous neolithic settlements identified by previous archaeological surveys represent the five major neolithic cultural stages i e the pengtoushan 9000 7900 cal yr bp zaoshixiaceng 7900 6800 cal yr bp daxi 6800 5500 cal yr bp qujialing 5500 5000 cal yr bp and shijiahe 5000 4000 cal yr bp using sedimentological and geoarchaeological approaches this paper analyses the drivers of basin scale settlement relocation in relation to lake level fluctuations and monsoon climate variations in the holocene the relocation of neolithic sites around the lake shoreline and on the adjacent floodplain together with radiocarbon dated stratigraphy clearly indicates that the shape of the lake basin was an incised and elongated valley occupied by a lake in the early holocene which became a broad

climate change and human occupations in the lake daihai basin north central china over the last 4500 years a geo archeological perspective abstract high resolution climate variations since the last 4500 years in the monsoonal arid transition zone of north central china were revealed through the integration of proxies from sediment cores in the lake daihai basin human occupations in the lake basin deduced from archeological findings and historical literatures were then incorporated into the climate sequence to demonstrate the patterns of human responses to the climate changes and the recent anthropogenic effects it indicated that 1 climate dominated human environment adaptations prevailed prior to 2700 cal yr bp an amicable climate setting before 4100 cal yr bp would facilitate the growth of the laohushan culture lc in the lake basin while a pronounced deterioration of water thermal condition after that had led to human exodus and the collapse of the lc the reduced human activity in the lake basin indicated at 3800 3500 cal yr bp and a subsequent cultural blank at 3500 2700 cal yr bp were both in response to the climate and lake level fluctuations during 3800 2800 cal yr bp 2 transition to a positive human adaptation was seen at 2700 1100 cal yr bp represented by the exploitation of arable land for cultivation and animal husbandry as the lake contracted 3 an increasing human presence that affected environmental processes became more severe over the last 1100 cal yr bp this was basically due to the ongoing lake shore reclamation for cropping and more recently heavy metals emissions from fossil fuel combustion and local industries

development of interlaced mylonites cataclasites and breccias example from the towaliga fault south central appalachians abstract a variety of cataclastic rocks from crush breccias to cataclasites and silicified breccias are associated with retrograde mylonites along the towaliga fault zone of south central appalachians in georgia a zone of alternating breccias and quartz ultra mylonites bordered by quartz mylonites that are roughly laminated with mm scale mica rich bands of cataclasites occur subparallel to the mylonitic foliation elsewhere along the fault zone evidence for plastically deformed microfractures is found in discussing the mechanical evolution of these rocks two possibilities are considered a the cataclasis is an overprint representing deformation in an entirely brittle regime and b cataclasis and mylonitization occurred at t 300 c in a predominantly plastic regime within the framework of the latter model it is suggested that the cataclasite bands are either due to the relaxation of dilational stresses following downward propagation of seismic ruptures or represent strain induced seismic instabilities during plastic shearing

early mid holocene sea level change and coastal environmental response on the southern yangtze delta plain china implications for the rise of neolithic culture abstract we used a series of holocene sediment cores with ams 14c dated basal saltmarsh peat and supratidal sediment to reconstruct early mid holocene sea level change on the southern yangtze delta plain we also synthesized results for ca 150 late quaternary cores as well as archeological data to reveal the unique interplay between coastal evolution and neolithic cultural response relative sea level was ca 16 5 to 14 5 m from 8600 to 8500 cal bp and ca 6 to 4 m from 7400 to 7200 cal bp reflecting the rate of eustatic sea level rise but being ca 10 m higher possibly because of the effect of hydro istostasy three late pleistocene interfluve terraces t3 to t1 were revealed at burial depths of

structural evolution of a major appalachian salient recess junction consequences of oblique collisional convergence across a continental margin transform fault most orogenic belts exhibit broadly arcuate regional map view trends of structural patterns commonly the inflection between opposing curves recesses and salients is a transverse zone marking a linear array of along strike contrasts in regional structure and stratigraphy analysis of such transverse zones can provide insight into the processes affecting orogenic curvature curvature is especially distinctive along the west flank of the appalachians where the tightest salient recess juncture is a thinned skinned transverse zone in georgia separating the alabama recess and tennessee salient and extending entirely across the width of deformed laurentian cover rocks this zone s most notable feature is a large oblique hanging wall ramp within the frontal metamorphic allochthon formed during alleghanian collisional events the basal decollement steps several kilometers stratigraphically upward across this ramp from proterozoic basement and its overlying late proterozoic rift sequence tennessee salient southwestward into basal cambrian and younger rocks alabama recess this ramp resulted from oblique sinistral displacement of the allochthon against an earlier east facing dextral continental margin transform fault that initially separated adjacent rifted margins of opposite polarity differences in the distribution thickness and facies of units indicate that important variations in basin geometry existed across the curvature inflection before paleozoic deformation suggesting that the orogenic curvature in part results from an inherited basin architecture translation of the allochthon over the ramp caused deflection of the tectonic transport trajectory major cross folding and rotation of earlier structures associated out of plane deformation propagated outward across the foreland producing the array of thinned skinned transverse structures aligned into the transverse zone

a 2200 yr record of hydrologic variability from foy lake montana usa inferred from diatom and geochemical data abstract a 2200 yr long high resolution 5 yr record of drought variability in northwest montana is inferred from diatoms and 18o values of bio induced carbonate preserved in a varved lacustrine core from foy lake a previously developed model of the diatom response to lake level fluctuations is used to constrain estimates of paleolake levels derived from the diatom data high frequency decadal fluctuations in the de trended 18o record mirror variations in wet dry cycles inferred from banff tree rings demonstrating the sensitivity of the oxygen isotope values to changes in regional moisture balance low frequency multi centennial isotopic changes may be associated with shifts in the seasonal distribution of precipitation from 200 b c to a d 800 both diatom and isotope records indicate that climate was dry and lake level low with poor diatom preservation and high organic carbon nitrogen ratios subsequently lake level rose slightly although the climate was drier and more stable than modern conditions at a d 1200 lake level increased to approximately 6 m below present elevation after which the lake fluctuated between this elevation and full stage with particularly cool and or wetter conditions after 1700 the hydrologic balance of the lake shifted abruptly at 1894 because of the establishment of a lumber mill at the lake s outlet spectral analysis of the 18o data indicates that severe droughts occurred with multi decadal 50 to 70 yr frequency

holocene regression and the tidal radial sand ridge system formation in the jiangsu coastal zone east china abstract a radial tidal sand ridge system rtsrs spans more than 20 000 km 2 in the southwest yellow sea is fan shaped and stretches from qianggang toward the sea the marine rtsrs is located in a convergent divergent tidal current field cdtcf numerous drilling holes reveal an area of 3000 km 2 containing tidal sand strata in the jiangsu coastal plain on land adjacent to the marine rtsrs which stretches eastward from chengdong and is also a fan shaped with a central angle of 130 the tidal sand unit lies on a transgressive coastal barrier lagoon unit with an erosional surface between them and the latter unit is in turn lying on late pleistocene stiff mud the tidal sand unit is overlain by the littoral tidal flat unit and together they constitute the holocene regressive succession paleo current study reveals that a paleo current pattern similar to the modern marine cdtcf was present in the holocene sub aerial tidal sand strata therefore the sub aerial tidal sand bodies are deduced to be an ancient rtsrs that was formed during the holocene regression and gradually exposed and changed into land as the changjiang and huanghe deltas prograded both sub aerial and marine rtsrs should be formed in the same tidal depositional environment but in different development stages thus the radial tidal sand ridges in southwestern yellow sea should have formed not during the holocene transgression as most previous studies have inferred but in the process of holocene regression mineralogical analyses demonstrate that the sediment source of the sub aerial rtsrs initially came from the changjiang and later predominantly from the huanghe sea floor erosion by tidal currents may also provide sandy material to form the rtsrs drilling cores and ground penetrating profiles show that the paleo valleys in the study area are much smaller than the present distributaries of the changjiang river thus the presumption of direct sand supply by a large river to form the rtsrs through its apical area is cannot be supported after the sea level reached the present high stand the jiangsu coastline has been prograding seaward as the changjiang delta expanded and this progradation was accelerated when the huanghe debouched in the study area the nearshore part of rtsrs has been gradually changing into land while the entire rtsrs extends seawards in the process of the development the rtsrs apex changed from chengdong to qianggang at present the coastline is still moving seaward while the outer part of the rtsrs suffers from some erosion owing to reduction of sediment supply from both the changjiang delta and the abandoned huanghe delta

constraints from deep crustal structure on long term landform development of the british isles and eastern united states abstract it is assumed that some major landforms not easily explained by surface geology could be controlled by deep crustal properties the concept was first applied in the british isles and then to the u s atlantic provinces both regions were affected by similar orogenies in late precambrian paleozoic times and presently belong to the passive margins of the north atlantic ocean in both areas the pattern of rifting was greatly influenced by preexisting tectonic fabric of the continental crust in the british isles pre mesozoic structures are cut obliquely by the atlantic margin while in the u s border the present margin is nearly parallel to the paleozoic sutures the british isles were affected by differential block tectonics during the tertiary examples are given of regional scale landforms linked with crustal hinges recent data confirm the great heterogeneity of the crust beneath the british isles each crustal unit has its own isostatic response according to the state of stress and its own dynamic equilibrium between rock resistance erosion processes and uplift rate in the atlantic provinces of the united states the regional physiographic framework is simpler but allochthonous terranes thrust westward over the grenville basement and shelf sediments have buried some major discontinuities in the deep crust reverse faults associated with the nw se compressional stressfield are numerous but cannot explain regional scale landforms like the blue ridge escarpment above the piedmont rock control is not the direct cause of the escarpment the blue ridge from reaches its highest relief where discontinuities in the deep crust interfere with surficial geological features ocean to continent creep processes are suggested to explain the sustained uplift of the appalachian highlands and the relatively stable position of the mountainous front since middle mesozoic times

early holocene coastal settlements and palaeoenvironment on the shore of the baltic sea at parnu southwestern estonia abstract studies were conducted on 16 sections of buried organic matter pre ancylus lake and pre litorina sea and associated stone age cultural layers in the parnu area southwestern estonia buried organic beds are each part of a sedimentary sequence which is repeated forming two overlying sets of an orderly succession of five layers the organic sedimentation of the lower set set 1 occurred about 10 800 10 200 years bp and that of the upper set set 2 about 9450 7800 years bp associated with set 1 is the early mesolithic settlement of pulli and with set 2 are the stone age cultural layers at sindi lodja the early and middle mesolithic sites in estonia are concentrated on shores of rivers and lakes to utilise of a variability of resources the hunters and fishermen followed the ancient parnu river downstream to the receding shoreline of the yoldia sea after about 10 700 years bp they were forced to retreat inland in front of the transgressive ancylus lake shore which first inundated the paikuse area about 10 400 years bp and pulli and higher sites about 10 200 years bp the total amplitude of the transgression preceded 11 m and reached up to 14 m a s l in the area the litorina sea transgression reached 7 m a s l after 8000 7800 years bp the mesolithic neolithic and modern sites on top of each other in the parnu area may suggest that although years apart they were inhabited by the same group of people who stayed in the area and moved back and forth together with the shifting shoreline of the baltic sea

initiation of the changjiang yangtze delta and its response to the mid holocene sea level change abstract the changjiang yangtze delta in eastern china is one of the largest tide dominated deltas in the world to obtain a more detailed information on its initiation we drilled three sediment cores pk01 hg01 and xj03 from the uppermost region of the delta plain on the basis of sedimentary facies and ams 14c dating we identified three depositional systems 1 a fluvial system 2 an estuarine system and 3 a deltaic system including an initial delta estuary delta transition and a typical delta the maximum flooding surface separates the estuarine and deltaic systems and occurred at ca 8 0 cal kyr bp when brackish water intruded landward and reached the nanjing area the changjiang delta was initiated at the area between nanjing and yizheng when the sea level rise decelerated after the rapid rise in sea level during 9 0 8 2 cal kyr bp the subsequent evolution of the changjiang delta has been shown as a seaward development model of river mouth bars with shoreline migration the oldest river mouth bar called hongqiao sand body which is located most landward was dated at 6 0 5 5 cal kyr bp in this study nearly one thousand years younger than the previous estimates a tide dominated funnel shaped estuary was formed at 8 0 cal kyr bp and lasted until the hongqiao sand bar became exposed this stage is regarded as an aggradation dominated initial stage of the changjiang delta followed by a progradation dominated stage that is characterized by the formation of a series of seaward migrating river mouth bars a relative sea level highstand in the mid holocene may be associated with glacio hydro isostatic tilting

late quaternary evolution of the sub aqueous yangtze delta china sedimentation stratigraphy palynology and deformation abstract four sediment belts a d of the yangtze sub aqueous delta are defined from the sea bottom sediment distribution belt a delta front fine sand and silt with trough cross stratification belt b prodelta silty clay and clayey silt with abundant burrowing and rich in organic matter belt c prodelta to continental shelf sand silt clay with thin layers of sand and clay interbedded and belt d late pleistocene relict sands medium to fine grained mixed with shell fragments the late quaternary stratigraphy of the delta consists from bottom upward of late pleistocene terrigenous fluvial and lacustrine sand and mud holocene transgressive silt prodelta clay and delta front fine sand and silt in addition four pollen spore zones a d derived from these sediment sequences reveal a general trend of climate warming from early to late holocene the zone c distributed primarily within the prodelta muds provides evidence for a temperature maximum starting at ca 7000 years b p atlantic period this indicates that the delta initiation was essentially coeval with the climate optimum in early holocene sub bottom seismic surveys reveal three i iii acoustic facies facies i and ii are characterized by seaward remobilization of water saturated holocene prodelta muds facies iii is composed of highly contorted late pleistocene strata and mud diapirs that erupted from deep seated late pleistocene sediments in front of the estuarine depocenter gravity subsidence due to holocene sediment loading within the depocenter is the major factor in causing the deformation of underlying unconsolidated strata furthermore the sub aqueous yangtze delta proper is now obviously diverting to southeast owing to the long term tectonically induced southward shift of the river mouth and to the marine currents associated with the coriolis effect we thus predict that the large chongming island in river mouth area will have been coalesced with the northern yangtze coast in the recent future

lithological and palynological evidence of late quaternary depositional environments in the subaqueous yangtze delta china abstract ams 14c ages of post glacial core sediments from the subaqueous yangtze delta along with sedimentary structures and distributions of grain size pollen spores and dinoflagellate cysts show an estuarine depositional system from 13 to 8 4 cal ka bp and a deltaic system from 5 9 cal ka bp to the present the estuarine system consists of intertidal to subtidal flat estuarine and estuarine front facies characterized by sand mud couplets and a high sedimentation rate the deltaic system includes nearshore shelf and prodelta mud featured by lower sedimentation rate markedly fewer coastal wetland herbaceous pollens and more dinoflagellate cysts we explain the extremely high sedimentation rate during 9 2 8 4 cal ka bp at the study site as a result of rapid sea level rise high sediment load due to the unstable monsoonal climate and subaqueous decrease of elevation from inner to outer estuary a depositional hiatus occurred during 8 2 5 9 cal ka bp the transition from estuarine to deltaic system caused possibly by a shortage of sediment supply resulting from delta initiation in paleo incised yangtze valley and strong tidal or storm related reworking in offshore areas the subsequent development of deltaic system at the study site indicates accelerated progradation of yangtze delta post 5 9 cal ka bp

migration patterns of neolithic settlements on the abandoned yellow and yangtze river deltas of china archaeological records of the neolithic settlements on the eastern china coast between 35 n and 30 n an area covering the abandoned yellow river and the yangtze river delta plains reveal that neolithic people moved from the yellow river basin onto the northern coast for fishing hunting and dry land agriculture 7000 yr ago marine transgression interrupted their activities on the low lying 2 5 m in elevation coastal wetlands between 6000 and 5000 yr ago after which they reclaimed their land near the river mouths their migration routes on the southern yangtze delta plain indicate another scenario early neolithic communities moved onto the plain for wet rice cultivation despite relative sea level rise from 7000 to 4000 yr ago a large number of settlements were established on the lowlands between the eastern chenier ridges and the western taihu lake depression the chenier ridges with 1 0 m higher topography than the adjacent coastal area played a role in sheltering the neolithic people subsequently settlements waned considerably possibly due to further marine inundation combined with cold climate the present study shows that migration patterns of the neolithic settlements are closely associated with a gradually rising sea level between 7000 and 4000 yr ago

holocene environmental change and its impacts on human settlement in the shanghai area east china abstract archaeological excavations and environmental archaeological studies over many years in the shanghai area have provided a wealth of information for holocene environmental changes growth and decline of human settlements and man land interaction distribution of archaeological sites between 7000 and 3000 cal yr bp indicates a regression process and a southward advance of the coastline in the study area temporal and spatial analyses of 14 c dates for archaeological sites shell ridges buried trees and peat suggest that holocene environmental changes may well have been a major cause of the rise and fall of human settlements and their civilization a relative sea level curve of the shanghai area was derived from dated shell ridges and peat and correlates well with the reconstructed sea level curves of the yangtze delta and east china the development of human settlements was interrupted at least four times in the shanghai area matching four periods of high sea level peat accumulation and increase in shell ridges after which neolithic communities moved onto the plain and reclaimed their lowlands for rice cultivation the chenier ridges played an important role in sheltering the neolithic settlers the collapse of liangzhu culture about 4000 cal yr bp was followed by the less developed maqiao culture these studies suggest that extreme environmental and hydrological conditions such as terrestrial inundation caused by sea level rise and heavy rainfall contributed to the cessation of paddy exploitation and to the social stress that led to the liangzhu culture demise

asynchronous holocene optimum of the east asian monsoon abstract the spatial and temporal distribution of summer monsoon precipitation or effective moisture during the holocene has been reconstructed on the basis of geological data including lake levels pollen profiles and loess paleosol records in addition the summer july precipitation increment effective precipitation and monsoon strength index have been obtained from numerical modeling experiments both geological data and numerical modeling indicate that the holocene optimum as defined by peak east asian summer monsoon precipitation was asynchronous in central and eastern china reaching a maximum at different times in different regions e g ca 10 000 8000 yr ago in northeastern china 10 000 7000 yr ago in north central and northern east central china ca 7000 5000 yr ago in the middle and lower reaches of the yangtze river and ca 3000 yr ago in southern china in southwestern china the maximum appeared ca 11 000 yr ago but probably was related to the maximum landward extension of the indian summer monsoon the regional shift in the maximum precipitation belt from northwest to southeast over the past 10 000 yr is interpreted as a response to changing seasonality related to orbital forcing of the climate the southeastward shift of the east asian summer monsoon maximum is consistent with the progressive weakening of the summer monsoon as the summer solar radiation anomaly decreased progressively through the holocene and the east asian monsoon index declined while the early maximum in southwestern china matches the maximum of the indian monsoon index

hydrological changes facilitated early rice farming in the lower yangtze river valley in china a molecular isotope analysis the prosperity of neolithic rice agriculture along the yangtze river valley china under the humid east asian monsoon has been well documented however the way in which major hydrological changes influenced the expansion of rice farming remains elusive mainly because detailed climate records associated with critical periods of the development of early rice farming are still lacking here we present high resolution n alkane carbon 13 c and hydrogen d isotope data sampled every 5 cm from a 360 cm sedimentary sequence spanning an 5 k y period at the tianluoshan archaeological site in china s eastern coastal region combined with micropaleontological records our dual isotope data reveal a detailed climate change profile between 7 0 and 4 6 ka showing major hydrological changes that coincided with the early development of rice farming in the lower yangtze region two major evapotranspiration events indicated by synchronized positive 13 c and d shifts of as much as 5 13 c and 60 d are evident ca 7 0 ka and 6 4 ka and coincided with regional sea level changes our new isotope data suggest that these short drought climate conditions superimposed upon local sea level regressions opened suitable new habitats for expanding rice agriculture in the lower yangtze delta when subsequent humid climate regimes returned

phytolith and diatom evidence for rice exploitation and environmental changes during the early mid holocene in the yangtze delta abstract using phytolith analysis from a well dated and high resolution sediment sequence in the apex of northern yangtze delta we investigate environmental changes the rise and decline of rice exploitation and possible impacts of environment on rice exploitation during the early mid holocene the phytolith sequence documents a relatively warm and dry interval during ca 9000 to 8200 cal yr bp followed by climatic amelioration before 7200 cal yr bp phytolith evidence indicates that rice exploitation at the apex of northern yangtze delta began at 8200 cal yr bp flourished by 7700 cal yr bp and ceased after 7400 cal yr bp the first emergence of marine diatom species approximately 7300 cal yr bp likely indicates an accelerated sea level rise the apparent correlation of the initiation of rice exploitation with climatic amelioration during the early mid holocene suggests that climatic changes may have played an important role in facilitating rice exploitation both the ideal climatic conditions and stable sea level enabled flourishing rice exploitation during 8200 to 7400 cal yr bp although the climate remained warm and wet after 7400 cal yr bp local sea level rise possibly led to the termination of earlier rice exploitation at this site of the northern yangtze delta

coastal gia processes revealed by the early to middle holocene sea level history of east china abstract in order to examine relative sea level responses to the postglacial ice volume change and the glacio hydro isostatic adjustments gia this study investigated the inner part of the hangzhou bay east china a tectonically relatively stable far field location and reconstructed the early to middle holocene sea level history this investigation has established the elevational relationship between modern saltmarsh mudflat and tidal levels based on diatom analysis for sea level indicative meaning estimates produced 17 high quality sea level index points and simulated gia processes for the study site these results reveal that the relative sea level rose from 38 3 1 6 m in c 10 000 cal a bp to the present height by c 7000 cal a bp and the average rate of sea level rise decreased gradually from 19 6 2 6 mm a to 2 3 1 5 mm a during the 3000 years this period of sea level history was punctuated by two episodes of accelerated rise around 8200 and 7500 cal a bp the relative sea level rose to 0 8 1 4 m above msl by c 6500 cal a bp followed by a gradual fall back to the present height at 4500 cal a bp implying a different response to the potential additional ice melting between 7000 and 4000 cal a bp a comparison of the sea level histories between the inner and outer hangzhou bay indicates the coastal levering effect due to the marine inundation of the continental shelves a further comparison between sea level data from china and malay peninsula reveals different gia effects between the cathaysia yangtze blocks and the sundaland block

south flank of the yangtze delta past present and future abstract chenier plain and mudflat development in the south flank of the yangtze delta are examined by multi disciplinary methods over different spatiotemporal scales and changing human earth interactions the study site contains a narrow belt of elongated ridge complexes that formed along the sediment deficient open coast from 6500 to 4000 yr bp since then and until the past two decades shoreline progradation has accelerated due to increasing sediment supply fueling rapid deltaic expansion superimposed on this trend are a series of discrete sand dominated ridges deposited during several stormy intervals tidal flat development is regulated by complex estuarine processes short term morphodynamic variations at the site are caused by the alternations of tides and waves while intermediate morphodynamic variations are controlled by the multi decadal shifting of river stem channel and stormy climates the ongoing rapid accretion on the tidal flats is predicted to continue into the near future because the estuarine buffer effect is expected to balance the adverse impacts of decreasing riverine sediment discharge and rising sea level technological developments during the last 2000 years are exemplified by seawall construction against sea flooding marking a transition from passive to active dike construction has been used more frequently and intensively to reclaim land since the 1970s in support of the booming socioeconomic development in the region lessons from complex morphodynamic change and human earth interactions in the southern yangtze delta admonish us to not reclaim coastal wetland by lower flat enclosures constructing new dikes near the low waterline while an optimal alternative would be to implement upper flat enclosures constructing new dikes around the high waterline on the continuously accretionary tidal flats with auxiliary biological restoration engineering to satisfy both socioeconomic development and sustainable wetland conservancy

holocene multidecadal and multicentennial droughts affecting northern california and nevada abstract continuous high resolution 18 o records from cored sediments of pyramid lake nevada indicate that oscillations in the hydrologic balance occurred on average about every 150 years yr during the past 7630 calendar years cal yr the records are not stationary during the past 2740 yr drought durations ranged from 20 to 100 yr and intervals between droughts ranged from 80 to 230 yr comparison of tree ring based reconstructions of climate change for the past 1200 yr from the sierra nevada and the el malpais region of northwest new mexico indicates that severe droughts associated with anasazi withdrawal from chaco canyon at 820 cal yr bp calendar years before present and final abandonment of chaco canyon mesa verde and the kayenta area at 650 cal yr bp may have impacted much of the western united states during the middle holocene informally defined in this paper as extending from 8000 to 3000 cal yr bp magnetic susceptibility values of sediments deposited in pyramid lake s deep basin were much larger than late holocene 3000 0 cal yr bp values indicating the presence of a shallow lake in addition the mean 18 o value of caco 3 precipitated between 6500 and 3430 cal yr bp was 1 6 less than the mean value of caco 3 precipitated after 2740 cal yr bp numerical calculations indicate that the shift in the 18 o baseline probably resulted from a transition to a wetter 30 and cooler 3 5 c climate the existence of a relatively dry and warm middle holocene climate in the truckee river pyramid lake system is generally consistent with archeological sedimentological chemical physical and biological records from various sites within the great basin of the western united states two high resolution holocene climate records are now available from the pyramid and owens lake basins which suggest that the holocene was characterized by five climatic intervals tic and 18 o records from owens lake indicate that the first interval in the early holocene 11 600 10 000 cal yr bp was characterized by a drying trend that was interrupted by a brief 200 yr wet oscillation centered at 10 300 cal yr bp this was followed by a second early holocene interval 10 000 8000 cal yr bp during which relatively wet conditions prevailed during the early part of the middle holocene 8000 6500 cal yr bp high amplitude oscillations in tic in owens lake and 18 o in pyramid lake indicate the presence of shallow lakes in both basins during the latter part of the middle holocene 6500 3800 cal yr bp drought conditions dominated owens lake desiccated and lake tahoe ceased spilling to the truckee river causing pyramid lake to decline at the beginning of the late holocene 3000 cal yr bp lake tahoe rose to its sill level and pyramid lake increased in volume

the alleghanian southern appalachian piedmont a transpressional model alleghanian dextral transpression produced multiple strike slip shear zones forming a contractional mega duplex in the central and southern appalachian piedmont structural upwelling along the zones is identifiable as crustal arching on seismic reflection profiles that roughly corresponds to the piedmont gravity high the structural upwelling coincides both temporally and spatially with areas of peak alleghanian plutonism and metamorphism the compositionally bimodal plutons generally occur in or around the fault zones and are isotopically primitive geobarometry of cognate xenocryst inclusions of coexisting plagioclase and pyroxene from a granitoid indicates 8 11 kbar or 31 to 42 5 km depth to proposed source region this depth roughly corresponds to the pre erosional location of multiple reflections beneath the arches on seismic profiles that are interpreted as the moho the granitoids are proposed to have formed by partial melting of the lowermost crust through heat from mafic intrusions and decompression resulting from crustal arching beneath the strike slip faults the granitoids ascended along the strike slip faults and were emplaced in or near them the crustal arching and melting processes appear to be important mechanisms in the development of strike slip orogens

late holocene moisture balance variability in the southwest yukon territory canada abstract analyses of sediment cores from marcella lake a small hydrologically closed lake in the semi arid southwest yukon provides effective moisture information for the last 4500 years at century scale resolution water chemistry and oxygen isotope analyses from lakes and precipitation in the region indicate that marcella lake is currently enriched in 18 o by summer evaporation past lake water values are inferred from oxygen isotope analyses of sedimentary endogenic carbonate in the form of algal charophyte stem encrustations a record of the 18 o composition of mean annual precipitation at jellybean lake a nearby evaporation insensitive system provides data of simultaneous 18 o variations related to decade to century scale shifts in aleutian low intensity position the difference between the two isotope records represents 18 o enrichment in marcella lake water caused by summer effective moisture conditions results indicate increased effective moisture between 3000 and 1200 cal bp and two marked shifts toward increased aridity at 1200 and between 300 and 200 cal bp these prominent late holocene changes in effective moisture occurred simultaneously with changes in aleutian low circulation patterns over the gulf of alaska indicated by jellybean lake the reconstructed climate patterns are consistent with the topographically controlled climatic heterogeneity observed in the coastal mountains and interior valleys of the region today

geochemical evidence for hydroclimatic variability over the last 2460 years from crevice lake in yellowstone national park usa abstract a 2460 year long hydroclimatic record for crevice lake yellowstone national park montana was constructed from the 18 o values of endogenic carbonates the 18 o record is compared to the palmer hydrologic drought index phdi and pacific decadal oscillation pdo indices as well as inferred discharge of the yellowstone river during the last century high 18 o values coincide with drought conditions and the warm phase of the pdo index low 18 o values coincide with wet years and a negative pdo index comparison of tree ring inferred discharge of the yellowstone river with the 18 o record over the last 300 years indicates that periods of high discharge i e wet winters with significant snow pack correspond with low 18 o values extrapolating this relationship we infer wet winters and high river discharge for the periods of 1090 1030 970 870 670 620 and 500 430 cal years bp the wet intervals at 670 and 500 cal bp are synchronous with similar events in banff canada and walker lake nevada the wet intervals at 970 and 670 cal bp overlap with wet intervals at walker lake and major drought events identified in the western great basin these results suggest that the northern border of yellowstone national park straddles the boundary between northern rocky mountains and great basin climate regimes

holocene climate fluctuations in the yangtze delta of eastern china and the neolithic response six major pollen spore assemblage zones can be identified showing alternate warm and cool climate fluctuations on a millennial timescale the early holocene optimum at c 8000 7800 radiocarbon year

holocene environmental changes of the songji lagoon south korea and its linkage to sea level and enso changes abstract as an important geomorphologic element of the coastal areas lagoons receive relatively less attention than estuaries and deltas in the nw pacific marginal sea in this study based on proxies of 13c pollen and diatoms from a sediment core we attempt to understand the holocene sedimentary environment of the songji lagoon south korea and the possible mechanism for its response to global or regional sea level and climate changes the sedimentary environment was phased in different periods an estuary an estuarine lagoon an intermediate environment and an intermediate to brackish lagoon in early holocene to 6 7 cal kyr bp 6 7 6 3 cal kyr bp 6 3 4 5 cal kyr bp and 4 5 1 3 cal kyr bp respectively afterward abundant freshwater entered the lagoon from the stream the environmental evolutions were triggered by sea level and climate changes the fluctuation of the sedimentary environment implies that the sea level rose from 4 5 to 2 2 cal kyr bp and declined from 2 2 to 0 8 cal kyr bp the sedimentary environmental change is also probably connected with el nino activity especially in the periods 6 7 6 3 cal kyr bp 4 5 3 6 cal kyr bp and 3 0 2 0 cal kyr bp

mid holocene coastal hydrology and salinity changes in the east taihu area of the lower yangtze wetlands china abstract during the mid holocene the eastern taihu area on china s yangtze delta plain was populated by advanced late neolithic cultures supported by intensive domesticated rice cultivation this agricultural system collapsed around 4200 cal yr bp with severe population decline the end of the liangzhu culture and about half a millennium of very low scale human activity in the area before the re establishment of agricultural production microfossil analyses from six sedimentary sequences supported by ams 14c dating has allowed reconstruction of mid holocene hydrological conditions and salinity changes which would have had a major influence on agricultural viability and cultural history in the coastal wetlands these data allied to existing stratigraphic and sea level records show that chenier ridges that developed after ca 7000 cal yr bp in the east of the area sheltered it from marine inundation and although still connected to the sea through tidal creeks low salinity conditions persisted throughout the neolithic period there is no evidence that marine flooding caused the collapse of liangzhu culture marine influence was stable and evolved slowly social and cultural causes may also have been important but if environmental change triggered the collapse of neolithic agricultural society here other natural forces must be sought to explain this event

depocenter shift and en echelon shoal development in the pre holocene incised valley of the yangtze delta china abstract this study establishes a holocene sedimentation model for the incised valley of the yangtze delta based on key information taken from existing literature and new cores collected for this study distinctive sedimentary processes and mechanisms operating in the incised valley were revealed 1 the significant role of a pre holocene incised valley on which the holocene funnel shaped bay was established in forming the topography of the present river mouth 2 the backstepping migration of the depocenter in association with tidally dominated sandy shoals developed in the early middle holocene followed by fluvially tidally dominated progradation during the mid late holocene 3 the model of depocenter shift characterized by en echelon sandy shoals in the incised valley revealing stepwise migration from transgressive to retrogressive sedimentation in the holocene and 4 the dextral diversion of the river mouth controlled by strong tidal sedimentation in the valley and the coriolis driven tidal sedimentation off the valley throughout the holocene our results further show that the sediment in the holocene valley was characterized by an upward increase in foraminiferal abundance this is a reversal of the usual pattern to the holocene marine transgression indicating a unique depositional setting in the valley presumably due to higher turbidity and poor preservation caused by strong tidal currents

neolithic agriculture freshwater resources and rapid environmental changes on the lower yangtze china analyses of sedimentary evidence in the form of spores pollen freshwater algae dinoflagellate cysts phytoliths and charcoal from ams 14c dated holocene aged sequences provide an excellent opportunity to examine the responses of neolithic agriculturalists in the lower yangtze to changing environments evidence from two sites close to the southern margin of the yangtze delta and separated by what is now hangzhou bay attests the critical importance to early attempts at food production of access to freshwater resources more readily if episodically available freshwater resources during the early to mid holocene on the hangjiahu plain may have encouraged an early reliance on rice based agriculture which in turn facilitated the accumulation of agricultural surpluses and cultural diversification cultural change was relatively attenuated and human population pressures possibly lower on the ningshao plain seemingly because of much more profound environmental impacts of variations in local hydrological conditions and because predominantly saline conditions associated with rising relative sea level hampered the early development of irrigated agriculture the evidence although largely dating to the early and middle parts of the holocene provides a timely warning of the complexity of vulnerability to climate change induced processes of agriculture and indeed human activities more generally on megadeltas in asia

pine mountain terrane a complex window in the georgia and alabama piedmont evidence from the eastern termination the pine mountain terrane is exposed in a complex window within the piedmont of georgia and alabama the eastern end of the terrane is framed by three ductile faults of demonstrably different ages the polydeformed pre thermal peak box ankle fault is truncated to the south by the younger pre thermal peak goat rock fault and to the north by the even younger post thermal peak towaliga fault the three faults framing the eastern termination of the window are clearly neither 1 part of the same detachment nor 2 part of the appalachian detachment

rising waters new geoarchaeological evidence of inundation and early agriculture from former settlement sites on the southern yangtze delta china new pollen phytolith charcoal and diatom data from 14c ams dated sediments from three clusters of former occupation sites on the southern yangtze delta liangzhu majiabang and chuodun reveal

shoreline reconstructions for the persian gulf since the last glacial maximum abstract sea level change in the persian gulf since the time of the last maximum glaciation at about 18 000 yr bp is predicted to exhibit considerable spatial variability because of the response of the earth to glacial unloading of the distant ice sheets and to the meltwater loading of the gulf itself and the adjacent ocean models for these glacio hydro isostatic effects have been compared with observations of sea level change and palaeoshoreline reconstructions of the gulf have been made from the peak of the glaciation until about 14 000 yr bp the gulf is free of marine influence out to the edge of the biaban shelf by 14 000 yr bp the strait of hormuz had opened up as a narrow waterway and by about 12 500 years ago the marine incursion into the central basin had started the western basin flooded about 1000 years later momentary stillstands may have occurred during the gulf flooding phase at about 11 300 and 10 500 yr bp the present shorelines was reached shortly before 6000 yr ago and exceeded as relative sea level rose 1 2 m above its present level inundating the low lying areas of lower mesopotamia these reconstructions have implications for models of the evolution of the euphrates tigris karun delta as well as for the movements of people and the timing of the earliest settlements in lower mesopotamia for example the early gulf floor would have provided a natural route for people moving westwards from regions to the east of iran from the late palaeolithic to early neolithic

impacts of human activity on the late holocene development of the subaqueous yangtze delta china as shown by magnetic properties and sediment accumulation rates development of the yangtze delta during the late holocene and its relationship to human activities in the drainage basin was analyzed using data from 16 cores collected from distributaries to the

integrating seismic reflection and geological data and interpretations across an internal basement massif the southern appalachian pine mountain window usa the southern appalachian pine mountain window exposes 1 1 ga grenvillian basement and its metasedimentary paleozoic cover through the allochthonous inner piedmont the issue of whether the crustal block inside the window was either transported above the master appalachian late alleghanian decollement or is an autochthonous block that was overridden by the decollement has been debated for some time new detrital zircon geochronologic data from the cover rocks inside the window suggest this crustal block was derived from gondwana but docked with laurentia before the alleghanian event reprocessed deep seismic reflection data from west central georgia pr and poststack noise reduction amplitude variation analysis and prestack depth migration indicate that a significant band of subhorizontal reflections occurs almost continuously beneath the window collinear with the originally recognized decollement reflections north of the window a marked variation in the decollement image from strong and coherent north of the window to more diffuse directly beneath the window is likely a partial consequence of the different geology between the inner piedmont and the window the more diffuse image beneath the window may also result from imaging problems related to changes in topography and fold of cover i e signal to noise ratio two alternative tectonic models for the pine mountain window can partially account for the observed variation in the decollement reflectivity 1 the pine mountain block could be truncated below by a relatively smooth continuation of the decollement the window would thus expose an allochthonous basement duplex or hors block thrust upward from the south along the late proterozoic rifted continental margin 2 the window represents localized exhumation of autochthonous basement and cover along a zone of distributed intrabasement shearing directly beneath the window either model is viable if only reflector geometry is considered model 1 is favored if both geometry and kinematics of blue ridge piedmont thrust sheet emplacement are incorporated in either model the southern margin of the window merges to the west with the iapetan early alleghanian central piedmont suture which juxtaposes north american affinity piedmont rocks to the north and exotic panafrican rocks of the carolina avalon terrane to the south immediately south of the window this suture dips southward and merges in the lower crust with the late alleghanian suture joining the appalachians with gondwana

impacts of sediment retention by dams on delta shoreline recession evidences from the krishna and godavari deltas india river deltas are the major repositories of terrestrial sediment flux into the world s oceans reduction in riverine inputs into the deltas due to upstream damming might lead to a relative dominance of waves tides and currents that are especially exacerbated by coastal subsidence and sea level rise ultimately affecting the delta environment analysis of multi date satellite imagery and maps covering the krishna and godavari deltas along the east coast of india revealed a net erosion of 76 km2 area along the entire 336 km long twin delta coast during the past 43 years 1965 2008 with a progressively increasing rate from 1 39 km2 yr 1 between 1965 and 1990 to 2 32 km2 yr 1 during 1990 2000 and more or less sustained at 2 25 km2 yr 1 during 2000 2008 at present the krishna has almost become a closed basin with decreased water discharges into the delta from 61 88 km3 during 1951 1959 to 11 82 km3 by 2000 2008 and the suspended sediment loads from 9 million tons during 1966 1969 to as low as 0 4 million tons by 2000 2005 in the case of the godavari delta although the water discharge data do not show any major change there was almost a three fold reduction in its suspended sediment loads from 150 2 million tons during 1970 1979 to 57 2 million tons by 2000 2006 a comparison of data on annual sediment loads recorded along the krishna and godavari rivers showed consistently lower sediment quantities at the locations downstream of dams than at their upstream counterparts reports based on bathymetric surveys revealed considerable reduction in the storage capacities of reservoirs behind such dams apparently sediment retention at the dams is the main reason for the pronounced coastal erosion along the krishna and godavari deltas during the past four decades which is coeval to the hectic dam construction activity in these river basins copyright 2010 john wiley and sons ltd

palynological evidence for early to mid holocene sea level fluctuations over the present day ningshao coastal plain in eastern china abstract sea level fluctuation in a coastal plain setting was crucial for neolithic human occupations of the ningshao coastal plain in eastern china in this study we carry out analyses using detailed palynological records of dinoflagellate cysts dinocysts freshwater algae and foraminiferal organic linings from two sediment cores hmd1501 and hmd1502 at the tianluoshan archaeological site zhejiang province eastern china brief sea level fluctuations and environmental changes on the ningshao coastal plain during the early to mid holocene were recovered by using radiocarbon chronology the results show the tianluoshan site underwent marine transgression processes and experienced warm and humid climatic conditions during the ca 10 708 5850 cal yr bp after that there was a relatively cold and dry climate marine regression processes occurred at the tianluoshan site during the ca 5850 5655 cal yr bp indicated by an abrupt increase in the cold water species of dinoflagellates especially o centrocarpum freshwater algae concentration and the ratio of pollen to dinoflagellates p d with an abrupt decrease appeared in foraminifer linings concentration marine regression processes provided an opportunity for hemudu ancestors to enter the tianluoshan site which helped create a brilliant hemudu tianluoshan culture on the ningshao coastal plain

mid holocene sea level highstand along the southeast coast of china various sea level curves have been proposed for the coast of china in the past two decades these sea level curves indicate a complex history of holocene sea level and so the debate on whether or not a higher mid holocene sea level highstand exists in the coast of china has continued this paper aims to re examine the holocene sea level history for the low latitude part of the china coast between 18 n and 32 n by re assessing all the sea level data available from the east to south coasts and separating them according to geological settings in order to examine the influences of global and local factors the reconstructed sea level histories from different coastal sectors of the china coast reveal a certain degree of variability in the timing and height of mid holocene sea level highstand within large river deltas the mid holocene sea level highstand occurred earlier by almost 1000 years than that from other coastal sites the highstand from large river deltas appears also lower in altitude a few metres below the present day sea level due probably to the local factors of subsidence and sediment consolidation in geologically stable coastal sites the highstand is recorded at the same altitude as the present day sea level a 1 2 m higher highstand is found from sites where tectonic uplift is observed

a unique middle pleistocene beech fagus rich deciduous broad leaved forest in the yangtze delta plain east china its climatic and stratigraphic implication abstract pollen analysis of middle pleistocene sediments from the yangtze delta plain provides a paleoecological reconstruction and has implications for stratigraphic correlation in east china the pollen assemblage is characterized by high values of fagus 16 8 on average which is unusual because fagus is generally present only sporadically in other lowland quaternary pollen records from the region in addition to fagus the assemblage has a rich diversity of broad leaved deciduous trees including quercus ulmus carpinus ostrya juglans betula and liquidambar as well as conifers including pinus picea abies larix and tsuga thus the pollen flora suggests a broad leaved deciduous forest mixed with abundant conifers which developed under cooler and more humid conditions than present the stable pollen sequence throughout the studied section suggests a stable environment beech forests also characterize the middle pleistocene of taiwan and japan and thus may be a stratigraphic indicator of the middle pleistocene in east asia the yangtze delta plain may have been an important refugium for the last survival of fagus in the lowlands