sedimentary characteristics and origin of the late pleistocene ice complex on north east siberian arctic coastal lowlands and islands a review abstract the origin of late pleistocene ice rich fine grained permafrost sequences ice complex deposits in arctic and subarctic siberia has been in dispute for a long time corresponding permafrost sequences are frequently exposed along seacoasts and river banks in yedoma hills which are considered to be erosional remnants of late pleistocene accumulation plains detailed cryolithological sedimentological geochronological and stratigraphical results from 14 study sites along the laptev and east siberian seacoasts were summarized for the first time in order to compare and correlate the local datasets on a large regional scale the sediments of the ice complex are characterized by poorly sorted silt to fine sand buried cryosols toc contents of 1 2 4 8 wt and very high ground ice content 40 60 wt absolute a second large constituent of the ice complex are large syngenetic ice wedges resulting in a total ice content of the ice complex of up to 80 vol ice complex deposits were mostly formed during the middle weichselian interstadial and or during the late weichselian stadial periods a conceptual model of nival lithogenesis of ice complex deposits was developed that integrates various other formation hypotheses a combination of various local and regional paleogeographical geological and paleoclimate conditions controlled the formation of ice complex sequences during the late pleistocene in northern east siberia they are chronologically and stratigraphically but not genetically equivalent to eurasian and alaskan loess deposits

effect of vegetation on an ice age climate model simulation a growing number of studies suggest that vegetation changes can significantly influence regional climate variations herein we utilize a climate model genesis with a land surface vegetation package to evaluate the potential role of the very large vegetation changes that occurred during the last glacial maximum lgm in particular we focus on the potential response to a significant reduction in the area of tropical rainforest simulations employed a global vegetation reconstruction for the lgm and climate long range investigation mapping and prediction climap sea surface temperature sst estimates results indicate that expansion of dryland vegetation causes a 15 30 additional lgm cooling for australia 0 4 c and africa 0 9 c respectively turnover from conifer to tundra also causes cooling of 2 4 c or more in western europe and siberia however for the largest rainforest area amazon basin inclusion of realistic vegetation increased modeled temperatures 2 4 c and decreased precipitation by 10 35 these latter results are similar to those obtained with sensitivity experiments of the effects of future amazon deforestation initial assessment of the potential effect of decreased stomatal resistance due to lower ice age co2 levels indicates little significant response to this effect comparison of model predicted low elevation lgm temperature changes with estimates from proxy data indicate that inclusion of realistic vegetation estimates for the lgm results in slightly more than 50 agreement between models and data for low elevation sites in low mid latitudes data at variance with model predictions would appear to be explainable by considering additional changes in vegetation ice age dust or a 1 2 c cooling below climap values this conclusion is at variance with a 3 4 c tropical cooling suggested by some studies for explaining estimated land temperature changes during the lgm in some western european sites model temperatures are colder than proxy data by 2 8 c this model data discrepancy may be explained by less sea ice in the subpolar north atlantic than stipulated by climap a conclusion consistent with new marine data from that region

tropical climates at the last glacial maximum a new synthesis of terrestrial palaeoclimate data i vegetation lake levels and geochemistry palaeodata in synthesis form are needed as benchmarks for the palaeoclimate modelling intercomparison project pmip advances since the last synthesis of terrestrial palaeodata from the last glacial maximum lgm call for a new evaluation especially of data from the tropics here pollen plant macrofossil lake level noble gas from groundwater and delta 18 o from speleothems data are compiled for 18 2 ka c 14 32 degrees n 33 degrees s the reliability of the data was evaluated using explicit criteria and some types of data were re analysed using consistent methods in order to derive a set of mutually consistent palaeoclimate estimates of mean temperature of the coldest month mtco mean annual temperature mat plant available moisture pam and runoff p e cold month temperature mat anomalies from plant data range from 1 to 2 k near sea level in indonesia and the s pacific through 6 to 8 k at many high elevation sites to 8 to 15k in s china and the se usa mat anomalies from groundwater or speleothems seem more uniform 4 to 6 k but the data are as yet sparse a clear divergence between mat and cold month estimates from the same region is seen only in the se usa where cold air advection is expected to have enhanced cooling in winter regression of all cold month anomalies against site elevation yielded an estimated average cooling of 2 5 to 3 k at modern sea level increasing to approximate to 6 k by 3000m how ever neotropical sites showed larger than the average sea level cooling 5 to 6 k and a non significant elevation effect whereas w and s pacific sites showed much less sea level cooling 1 k and a stronger elevation effect these findings support the inference that tropical sea surface temperatures ssts were lower than the climap estimates but they limit the plausible average tropical sea surface cooling and they support the existence of climap like geographic patterns in sst anomalies trends of pam and lake levels indicate wet lgm conditions in the w usa and at the highest elevations with generally dry conditions elsewhere these results suggest a colder than present ocean surface producing a weaker hydrological cycle more arid continents and arguably steeper than present terrestrial lapse rates such linkages are supported by recent observations on freezing level height and tropical ssts moreover simulations of greenhouse and lgm climates point to several possible feedback processes by which low level temperature anomalies might be amplified aloft

sedimentary features influencing the occurrence and spatial variability of seismites late messinian gargano promontory southern italy abstract seventeen layers characterized by soft sediment deformation structures ssds were identified within the calcari di fiumicello an upper messinian miocene stratigraphic unit 30 m thick cropping out in the northern sector of the gargano promontory apulia southern italy facies analysis was performed on the whole outcrop and detailed sedimentological investigations were carried out on the deformed beds in order to interpret the deformation mechanism the driving mechanism and the possible trigger agent deformed layers occur in some thin bedded ooidal limestones skeletal calcarenite as well as in some pebble size conglomerate alternated with marls deposited in a protected embayment or barrier island lagoon system possibly characterized by high salinity and tidal influx ssds can be classified as load and slump slide structures the continuous exposures allow us to follow a single deformed layer along tens of meters hence several types of lateral variations were observed that can be summarised as follows 1 ssds disappear within a few meters with a decreasing pattern of their deformation or in an abrupt way 2 deformed layers laterally change in thickness and morphology and 3 a single deformed bed can laterally correspond to two deformed beds most of the soft sediment deformation features were identified as liquefaction and or fluidization features related to seismic shocks seismites seismites are often used as an indicator of seismic events especially along small outcrops trench excavation and core analysis this study highlights the value of the sedimentological analysis for paleoseismic investigations with the aim of improving criteria for identifying seismites in the sedimentary record and their suitability as marker of seismic events

how a wet tropical rainforest copes with repeated volcanic destruction the holocene period for the province of west new britain papua new guinea is characterised by periodic catastrophic volcanism the region is mantled in dense wet tropical rainforest and has been occupied by people since the pleistocene analyses of peat from two nearby sites within a lowland rainforest environment provide us with a macro level landscape account of the periodic destruction and recovery of the coastal forests during seven periods of volcanic activity in the latter part 2900 yr ago to present of the holocene radiocarbon dating shows the very close correlation of the peat and tephra layers at both sites yet the pollen analysis reveals different vegetation communities these initial results allow us to begin identifying the processes of recovery and to recognise different ecological pressures placed on vegetation at these neighbouring sites evidence of hydrological changes are observed beginning with a marine incursion recorded at garu site 3 1360 14 c yr b p the distinct differences in the vegetation re establishment and community regeneration rates suggest the greater level of disturbance at garu site 1 could be related to the depth of the ashfall although the proximity of a known human settlement may also be a contributing factor of note palynologically we found that the fern spore flora is particularly rich and believe it will be useful for ecological interpretation d 2005 university of washington all rights reserved

a late quaternary record of environmental change and human impact from new caledonia a late quaternary vegetation record is presented from a lowland site on the leeward southwest coast of new caledonia plum swamp is a backswamp on the plum river at around 10 m a s l just within the ultramafic terrain that dominates the southern third of new caledonia pollen analysis charcoal analysis radiocarbon dating and stratigraphic analysis are employed to reconstruct the vegetation and sedimentary history of the valley the vegetation record commences at around 20 000 yr bp and shows that from this time up until the late holocene the valley was forested the greater representation of taxa more prevalent at higher altitudes during the late glacial suggests a response to cooling and an enrichment of the lowland forest with more montane elements the late glacial transition between 14 000 and 9000 yr bp is a period of instability within the valley when vegetation is disturbed by fire forest recovers after this and there is increasing stability until the arrival of people in the late holocene at around 3000 yr bp the initial colonisers of new caledonia had a profound effect upon the vegetation of the valley converting the lowland forest to a stunted and species poor maquis on the ultramafic sediments and melaleuca woodland on the non ultramafic substrates however sedimentary processes are relatively unchanged during this time dramatic geomorphic change does occur in the catchment though during the latter part of the 20th century as a consequence of mining q 2001 elsevier science b v all rights reserved

palaeoenvironmental developments in the lake tondano area n sulawesi indonesia since 33 000 yr b p abstract geo morpho logical sedimentological and ecological developments in the lake tondano area since 33 000 yr b p and limnological changes in the moderately sized lake situated at 680 m asl in the northern part of sulawesi indonesia are discussed first the environmental setting of the lake is presented study of the regional distribution of lacustrine sediments and a detailed analysis of their sedimentary facies texture organic matter content suggest major changes in size and depth of the lake and in past sedimentation insight into the long term development of the lake sedimentation processes is highly relevant for sustainable use of the present lake analysis of diatom assemblages provides further detail of the changing aquatic settings of the lake lake levels rise quickly around 33 000 and 12 000 yr b p fall dramatically between 30 000 and 13 000 yr b p and are lowered gradually since approximately 6000 yr b p following early holocene high lake levels drainage of the lake is affected by both volcanic depositional events and regional climatic events palynological analysis is indicative of local palaeoecological settings in the lake area and regional climatic change a distinct late pleistocene phase with lower precipitation and lowered mean temperatures is inferred furthermore progressive deforestation of the tondano uplands is evident as well as diffuse anthropogenic volcanic vegetation disturbance from the early mid holocene onwards information from sedimentary facies diatom assemblages and local palaeoecology pollen are integrated to reconstruct palaeoenvironmental settings and processes in the lake area this record of environmental change as well as the pollen based record of regional vegetation and climate change corroborates other palaeoenvironmental data derived from the few terrestrial sites in the region the data attribute a greater magnitude of temperature and precipitation change in the region than is commonly deduced in studies based on marine faunal and sedimentary records the lake tondano sedimentary record is highly suitable for further analysis aimed at determining the exact timing and amplitudes of environmental change in the se asian equatorial region

a comparison of late quaternary forest changes in new caledonia and northeastern australia a pollen record from lake xere wapo southeast new caledonia is the longest continuous terrestrial record to be recovered from the tropical southwest pacific and reveals a series of millennial scale changes in vegetation over the last 130 000 yr a comparison of the lake xere wapo record with the key northeast australian record of lynch s crater reveals regional patterns of change from 120 000 to 50 000 yr ago the vegetation around lake xere wapo alternated between rainforest and maquis with fire an important disturbance factor in the last 50 000 yr fire is almost absent from the record and the vegetation assumes a character unprecedented in the preceding 100 000 yr dominated by dacrydium and podocarpus pollen the most compelling aspect of the comparison with lynch s crater is that the much discussed araucaria decline at around 45 000 yr ago in northern queensland is matched by a similar decline in the lake xere wapo record d 2005 university of washington all rights reserved

geological and geomorphological evolution of a sedimentary periglacial landscape in northeast siberia during the late quaternary a wide variety of environmental records is necessary for analysing and understanding the complex late quaternary dynamics of permafrost dominated arctic landscapes a ne siberian periglacial key region was studied in detail using sediment records remote sensing data and terrain modelling all incorporated in a geographical information system gis the study area consists of the bykovsky peninsula and the adjacent khorogor valley in the kharaulakh ridge situated a few kilometres southeast of the lena delta in this study a comprehensive cryolithological database containing information from 176 sites was compiled the information from these sites is based on the review of previously published borehole data outcrop profiles surface samples and our own field data these archives cover depositional records of three periods from pliocene to early pleistocene the late pleistocene and the holocene the main sediment sequences on the bykovsky peninsula consist of up to 50 m thick ice rich permafrost deposits ice complex that were accumulated during the late pleistocene they were formed as a result of nival processes around extensive snowfields in the kharaulakh ridge slope processes in these mountains such as in the khorogor valley and alluvial proluvial sedimentation in a flat accumulation plain dominated by polygonal tundra in the mountain foreland bykovsky peninsula during the early to middle holocene warming a general landscape transformation occurred from an extensive late pleistocene accumulation plain to a strongly thermokarst dominated relief dissected by numerous depressions thermokarst subsidence had an enormous influence on the periglacial hydrological patterns the sediment deposition and on the composition and distribution of habitats climate deterioration lake drainage and talik refreezing occurred during the middle to late holocene the investigated region was reached by the post glacial sea level rise during the middle holocene triggering thermo abrasion of ice rich coasts and the marine inundation of thermokarst depressions

holocene and latest pleistocene activity on the mesquite lake fault near twentynine palms eastern california shear zone implications for fault interaction paleoseismic data from the mesquite lake fault reveal evidence for up to four prehistoric earthquakes since the latest pleistocene with three large surface rupturing events in about the past 10 2 ka three events were recorded in trenches excavated for this investigation on mesquite lake playa a buried fault scarp brack eted by accelerator mass spectrometer radiocarbon ages of detrital charcoal indicate that a mid to late holocene event occurred between about 2 7 and 7 4 ka most likely between about 3 9 and 4 6 ka an early holocene rupture defined by a subtle buried scarp and upward terminating fissures is bracketed between about 7 7 and 10 2 ka evidence for an inferred late pleistocene event prior to about 10 2 ka includes a subtle scarp upward termination of faults folding and in filled craters and fissures a previous paleoseismic investigation just south 2 km of the playa identified at least one event in the past 1 3 ka although this event was not identified in this study at the playa site apparent vertical offsets of about 1 0 m and 1 2 m for the last two events at the playa site suggest a sequence of similar serial ruptures these separa tions are comparable to the height of surficial scarps just south of the playa because the vertical separations produced by each event are similar the mesquite lake fault at least locally experiences similar slip per event since the initiation of holocene playa development just over 10 2 ka ago we estimate a horizontal slip rate of 0 7 0 9 mm yr 1 that is consistent with slip rates for other faults in the eastern california shear zone despite large uncertainties event stratigraphy at the playa site shows that periods of quiescence up to thousands of years separated large ruptures similar to other faults in the eastern california shear zone comparison of paleoseismic studies in the eastern california shear zone suggest that the mesquite lake and possibly the bullion and lavic lake faults in the eastern part of the shear zone may have failed during periods of seismic quiescence in the western part of the zone at about 1 5 ka this suggests that seismic strain release may vary spatially across the shear zone and that temporal clusters of earthquakes are not necessarily spatially limited to specific regions

paleoenvironmental and paleoclimatic records from permafrost deposits in the arctic region of northern siberia ice complexes extremely ice rich permafrost deposits with large ice wedges are widely distributed in the arctic region of northeast siberia they present excellent archives for the reconstruction of late quaternary paleoenvironmental conditions in nonglaciated areas in 1998 1999 and 2000 russian and german scientists worked together on the bykovsky peninsula southeast of the lena delta in order to investigate the ice complex and its associated sediments intensive cryolithological and sedimentological studies radiocarbon age determinations paleobotanical studies micropaleontological investigations studies of mammal and insect fossils and stable isotope analyses of ground ice were performed radiocarbon data have been obtained from the entire exposed sequence coveringapproximately the last 60 000 years the results indicate that compared with modern time the investig ated ice complex sequence was formed duringtwo cooler and more arid stages of the late pleistocene with relatively uniform environmental conditions separated by a stage with environmental variations and more intensive soil formation caused by climate amelioration the late pleistocene environmental changes were not as strong as those occurring during the pleistocene holocene transition where a sharp break is evident r 2002 elsevier science ltd and inqua all rights reserved

climate variability over the last 35 000 years recorded in marine and terrestrial archives in the australian region an oz intimate compilation abstract the australian region spans some 60 of latitude and 50 of longitude and displays considerable regional climate variability both today and during the late quaternary a synthesis of marine and terrestrial climate records combining findings from the southern ocean temperate tropical and arid zones identifies a complex response of climate proxies to a background of changing boundary conditions over the last 35 000 years climate drivers include the seasonal timing of insolation greenhouse gas content of the atmosphere sea level rise and ocean and atmospheric circulation changes our compilation finds few climatic events that could be used to construct a climate event stratigraphy for the entire region limiting the usefulness of this approach instead we have taken a spatial approach looking to discern the patterns of change across the continent the data identify the clearest and most synchronous climatic response at the time of the last glacial maximum lgm 21 3 ka with unambiguous cooling recorded in the ocean and evidence of glaciation in the highlands of tropical new guinea southeast australia and tasmania many terrestrial records suggest drier conditions but with the timing of inferred snowmelt and changes to the rainfall runoff relationships driving higher river discharge at the lgm in contrast the deglaciation is a time of considerable south east to north west variation across the region warming was underway in all regions by 17 ka post glacial sea level rise and its associated regional impacts have played an important role in determining the magnitude and timing of climate response in the north west of the continent in contrast to the southern latitudes no evidence for cooling during the younger dryas chronozone is evident in the region but the antarctic cold reversal clearly occurs south of australia the holocene period is a time of considerable climate variability associated with an intense monsoon in the tropics early in the holocene giving way to a weakened monsoon and an increasingly el nino dominated enso to the present the influence of enso is evident throughout the southeast of australia but not the southwest this climate history provides a template from which to assess the regionality of climate events across australia and make comparisons beyond our region

a late pleistocene and holocene pollen and charcoal record from peat swamp forest lake sentarum wildlife reserve west kalimantan indonesia abstract a preliminary palynological record is presented from a peat swamp forest in the upper kapuas river basin in west kalimantan although the record is discontinuous it provides a picture of changing vegetation riverine and swamp environments and climate through parts of at least the last 30 000 years during the late pleistocene the composition of both riverine and swamp forests was different to that of the holocene temperatures were cooler especially during the last glacial maximum as indicated by the presence of components of submontane and montane vegetation the presence of charcoal demonstrates that the tropical lowland forests experienced fire through the whole of the recorded period however charcoal values generally rise through the period suggesting increased human impact through time highest burning levels and forest indicators of disturbance indicate most intensive human impact within the last 1400 years

sand boils without earthquakes sedimentary deformation caused by liquefaction has become a popular means for inferring prehistoric strong earthquakes in this report we describe a new mechanism for generating such features in the absence of earthquakes sand boils and a 180 m long sand dike formed in fremont valley california when sediment laden surface runoff was intercepted along the upslope part of a 500 m long preexisting ground crack flowed subhorizonally in the crack and then flowed upward in the downslope part of the crack where it discharged as sand boils on the land surface if the sand boils and their feeder dike were stratigraphically preserved they could be misinterpreted as evidence for earthquake induced liquefaction

quaternary glaciations in the verkhoyansk mountains northeast siberia geomorphological mapping revealed five terminal moraines in the central verkhoyansk mountains the youngest terminal moraine i was formed at least 50 ka ago according to new irsl infrared optically stimulated luminescence dates older terminal moraines in the western foreland of the mountains are much more extensive in size although the smallest of these older moraines moraine ii has not been dated moraine iii is 80 to 90 ka moraine iv is 100 to 120 ka and the outermost moraine v was deposited around 135 ka this glaciation history is comparable to that of the barents and kara ice sheet and partly to that of the polar ural mountains regarding the timing of the glaciations however no glaciation occurred during the global last glacial maximum mis 2 based on cirque orientation and different glacier extent on the eastern and western flanks of the verkhoyansk mountains local glaciations are mainly controlled by moisture transport from the west across the eurasian continent thus glaciations in the verkhoyansk mountains not only express local climate changes but also are strongly influenced by the extent of the eurasian ice sheets

the rain forest in java through the quaternary and its relationships with humans adaptation exploitation and impact on the forest abstract relations between humans and the rain forest in java island began during the lower pleistocene but clear evidence for anthropic impact and clearance of the forest does not occur until late in the holocene after the rise of the ancient kingdoms on java at the end of 1st millennium a d the history of landscape change in java over the last 2 5 million years appears highly complex and linked to the repetitive expansion and fragmentation of the rain forest over this time these processes are now much better understood thanks to the range of palaeoenvironmental studies undertaken at various altitudes and in locations that show the dynamics of rain forest in response to variations in climatic and regional environmental change the extent of rain forest throughout the holocene appears to have been quite sensitive to small perturbations making it somewhat difficult to discriminate especially for relatively ancient holocene forest recessions between a climatic cause and one of anthropic origin clear evidence of intensive human impact on rain forest is observed late c 1500 years ago a pattern that is repeated in other parts of island southeast asia this paper will focus on the history of the landscape changes in java during the quaternary with special reference to the dynamics of rain forest structure and composition largely drawn from available pollen analyses subsequently the paleoenvironmental palaeoanthropological and archaeological records are considered to investigate the adaptive relationships between human groups and the forest through time

compound specific carbon isotope records of vegetation and hydrologic change in central sulawesi indonesia since 53 000 yr bp lake matano 2 29 1 s 121 20 e in central sulawesi the deepest and one of the largest lakes in indonesia provides an excellent opportunity to reconstruct long term hydrological and vegetation changes at the heart of the maritime continent within the tropical western pacific warm pool we measured the carbon isotopic composition of terrestrial leaf waxes 13cwax in new sediment cores from lake matano to understand regional variations in vegetation and their interactions with local and high latitude climate forcings during the past 53 kyr variations in 13cwax record the expansion and contraction of c3 versus c4 vegetation as well as changes in plants carbon and water use efficiency and by inference regional hydroclimate during marine isotope stages 1 and 3 more negative 13cwax values indicate that closed canopy c3 rainforests predominated in sulawesi reflecting a wetter less seasonal climate in contrast more positive 13cwax values record a terrestrial ecosystem with more abundant open canopy vegetation and possible expansion of c4 grasses between 29 and 14 ka bp indicating that during marine isotope stage 2 including the last glacial maximum the climate was more arid likely with increased precipitation seasonality in central sulawesi comparison of our record with other paleovegetation and paleohydrological records from sulawesi and nearby islands suggests coherent long term hydrological changes in central indonesia that appear to be sensitive to high latitude climate across glacial interglacial boundaries however variations in the amplitude of the response of vegetation to these glacial interglacial forcings highlight the importance of regional topographic control on climate and vegetation and suggest an important role for higher elevations in maintaining rainforest refugia during regionally arid time intervals when c4 savannas and grasslands expanded at lower elevations

tropical vegetational change in the late pleistocene of new caledonia the south eastern plateau of new caledonia 22 s preserves remnants of a deep regolith of ultramafic soils which is extensively gullied or eroded to form large alluvial fans dated sediments from four closed basins on the plaine des lacs ca 220 m altitude show that organic muds were accumulating prior to 30 000 yr b p over the next 5000 14 000 years limonitic clays infilled two basins as a result of slope instability in their catchment resistant laterite and bog iron surfaces became exposed during the period 30 000 15 000 yr b p by erosional events that seem to have been of greater magnitude than any in the earlier pleistocene two sites lake emeric and lake suprin were chosen for pollen analysis during the phases of organic deposition of these lakes nothofagus forests collapsed several times and were replaced by gymnostoma maquis apparently as a result of fires these pleistocene fires were associated with some inorganic deposition presumably due to the substantial loss of primary forest cover regeneration of forest usually followed after an estimated gap of several centuries thus fire was able to cause forest retreats of the same order of magnitude as that caused by massive fires today the low nutritional status of the soils or lateritic crusts means that as now forest had difficulty reclaiming sites human activity is unknown prior to 3000 years ago so the major erosion is presumed to have had natural causes thus many of the wide ranging changes are the result of natural instability in the sub tropics and some may be much older than hitherto thought climate change towards periods of dry fire prone conditions may have been an underlying cause in the holocene some climatic factor possibly cyclonic storms seems to prevent organic sedimentation switching from cyclone free to cyclone prone at the end of the pleistocene may reflect temperature change in sea surfaces in the region

liquefaction features interpreted as seismites in the pleistocene fluvio lacustrine deposits of the neuquen basin northern patagonia abstract superbly exposed soft sediment deformation structures in pleistocene fluvio lacustrine deposits along the southern border of the depression area called bajo de anelo departamento de anelo neuquen basin have been analysed in the study area five stratigraphic sections were measured in detail facies distributions and stacking patterns show that these sediments result from the interaction between fluvial and lacustrine systems represented by cross bedded and rippled strata and varved deposits the lateral extent of the deformation is some hundred metres and the deformed bed involves the lower mid part of the 30 metre thick succession deformation affects about 1 5 m of coarse grained sand fine grained sand and rare gravel alternations the base and top of the deformed layer are defined by planar surfaces undeformed beds of similar thickness lithology and facies to the deformed layer occur above and below deformation is represented by a complex vertical succession of disturbed layers each layer shows a general load structure morphology it can be described as a multilayered unstable density gradient system in each bed a partial gravitational re adjustment occurred after liquefaction unequal loading related to lateral variation of both bed thickness and grain packing and porosity is a probable additional driving force that can be described in the undeformed beds trigger mechanism recognition for the observed liquefaction features can be based on the study of the geometry of deformed beds and on facies analysis results two key factors drive our interpretation 1 the occurrence of undeformed beds below and above the deformed bed 2 deformed and undeformed beds showing the same sedimentological features these field data allow us to exclude the action of internal erosive and or sedimentary processes such as overloading wave action etc as possible trigger agents for liquefaction since deformation is totally absent in beds with similar sedimentary features furthermore each internal erosive and or sedimentary process can be discussed and easily excluded by analysing its specific signature in the geological record having excluded every possible internal trigger autokinetic processes the observed liquefaction effects can reasonably be interpreted as seismically induced allokinetic trigger from this point of view this deformed bed is an important record of seismic activity in this sector of the neuquen basin during the pleistocene

a biomass burning record from the west equatorial pacific over the last 360 ky methodological climatic and anthropic implications abstract to reconstruct past fire activity in the west pacific east asian region we investigate a 360 ky pelagic sedimentary record from the caroline basin in the western pacific warm pool wpwp core md97 2140 2547 m water depth in the lack of standard protocol and terminology for the determination of combustion derived products in sedimentary archives three proxies were compared with other paleoceanographic proxies oxidation resistant elemental carbon orec black carbon bc and microcharcoal the mineral caco3 and organic carbon corg records of core md97 2140 generally covary with the oxygen isotope record suggesting that glacial interglacial changes in ice volume and sea level control the preservation of caco3 and terrigeneous inputs of corg in the deep sea sediments of the caroline basin the changes in orec are primarily connected to the changes in corg record in contrast the bc and charcoal records which better reflect the input of biomass burning products are tightly connected with changes in the precession band 23 ky likely through low latitude atmospheric circulation patterns a peculiar control by the competing influence of the long term el nino southern oscillation enso like forcing and the glacial interglacial cycle on the east asian summer monsoon 30 19 11 and 6 ky periods is suggested in addition large increases in bc and charcoal are observed between ca 53 43 and 12 10 ky bp these events strikingly correspond to the main late pleistocene and early holocene periods of human colonization in the region likely suggesting an additional anthropic impact on the fire activity

a late quaternary pollen record from ka au crater o ahu hawai i abstract a pollen record from ka au crater o ahu hawai i contains evidence for changes in vegetation and climate since about 28 000 14c yr b p zone 1 ca 28 100 ca 22 800 14c yr b p has pollen of dry to mesic forest species including pipturus type dodonaea viscosa acacia koa chenopodium oahuense claoxylon sandwicense myrsine and metrosideros type in zone 2 ca 22 800 ca 16 200 14c yr b p myrsine and coprosma increase with herbs fern allies and grammitidaceae suggesting open canopies zone 3 ca 16 200 ca 9700 14c yr b p has pollen of wet forest species including freycinetia arborea abundant pritchardia and metrosideros type zone 4 ca 9700 ca 7000 14c yr b p is similar with less pritchardia and more metrosideros type climate reconstruction was based on modern climatic ranges of flowering plants and an index derived from abundance of pollen in surface samples both methods agree on a qualitative reconstruction although the ages are poorly constrained 28 000 25 000 14c yr b p cool and dry 25 000 23 000 14c yr b p dry and warmer 23 000 20 000 14c yr b p moderately dry with declining temperature 20 000 16 000 14c yr b p moderately dry and cool 16 000 9000 14c yr b p warm and wet 9000 7000 14c yr b p warm and possibly drier lower precipitation at ka au crater during the late glacial period and last glacial maximum is consistent with the interpretation that the north pacific subtropical anticyclone was south of its present position the pollen derived temperature index yields an estimate of 3 5 c temperature depression during the last glacial maximum

a 135 000 year record of vegetational and climatic change from the bandung area west java indonesia sedimentological and palynological analyses of sediment cores from the intramontane bandung basin west java indonesia provide a first palaeoclimatic record for the indonesian region covering continuously the last 135 000 years our data on palaeosol development indicate anomalously dry conditions for the final part of the penultimate glacial period around 135 000 yr b p and very warm and humid interglacial conditions from 126 000 to 81 000 yr b p during the transition to the last glacial period around 81 000 yr b p freshwater swamp forest of the bandung plain was replaced by an open swamp vegetation dominated by grasses and sedges indicating a change to considerably drier conditions possibly related to reduced moisture uptake by the nw monsoon as a consequence of lower sea levels at the onset of glacial conditions a strong reduction in asplenium ferns from 81 000 to 74 000 yr b p suggests that drier conditions may also have occurred in the mountains of the bandung area while increased numbers indicate that from 74 000 to 47 000 yr b p it was slightly wetter again inferred depression of montane vegetation zones and reduced fern percentages suggests distinctly cooler and possibly drier climatic conditions prevailed in the bandung area from 47 000 to approximately 20 000 yr b p for the last glacial maximum 4 7 c lower temperatures are recorded

late pleistocene and holocene sedimentation organic carbon delivery and paleoclimatic inferences on the continental slope of the northern pandora trough gulf of papua 1 we investigated sediment and organic carbon accumulation rates in two jumbo piston cores mv 54 mv 51 retrieved from the midslope of the northeastern pandora trough in the gulf of papua papua new guinea our data provide a first assessment of mass fluxes over the past 33 000 14c years b p and variations in organic carbon sources core sediments were analyzed using a suite of physical properties organic geochemistry and micropaleontological measurements mv 54 and mv 51 show two periods of rapid sediment accumulation the first interval is from 15 000 to 20 400 cal years b p mv 51 1 09 m ka 1 and 81 2 g cm 2 ka 1 and the second occurs at 32 000 14c years b p 2 70 m ka 1 and 244 g cm 2 ka 1 extremely high accumulation rates 3 96 m ka 1 428 g cm 2 ka 1 characterize 15 800 17 700 cal years b p in mv 54 and likely correspond to early transgression when rivers delivered sediments much closer to the shelf edge a benthic foraminiferal assemblage in mv 51 from 18 400 to 20 400 cal years b p indicates a seasonally variable flux of organic carbon possibly resulting from enhanced contrast between monsoon seasons the oldest sediments 32 000 14c years b p contain toc fluxes 200 g cm2 ka 1 with 50 of it derived from c3 vascular plant matter magnetic susceptibility values are 2 to 3 times higher and benthic foraminiferal accumulation rates are 6 times higher during this interval than at any younger time indicating a greater influence of detrital minerals and labile organic carbon the ms data suggest more direct dispersal pathways from central and eastern png rivers to the core site

a long vegetation history from lowland irian jaya indonesia abstract this paper reports the pollen analysis of a 10 m core from a mire at 780 m altitude and 2 s latitude on ultrabasic soils on a northern coastal range of new guinea the area is almost undisturbed by humans and the record is believed to cover about 60 000 yr b p the results show that montane forest grew around the site continously through the late pleistocene with a distinct increases in higher altitude taxa from 25 000 to 10 500 yr b p the time of glacial maxima elsewhere the invasion of the site by lower altitude forest which commenced at 10 500 yr b p was reversed after a few hundred years and was not finally completed until about 7000 yr b p the results show that vegetation in the region has been sensitive to climatic change the pleistocene ecology being consistent with a temperature change of about 3 4 c times of change agree with other tropical areas even though the site climate was probably affected by changing sea levels however the tropical forest demonstrates overall long term stability in which changes in dominance may reflect minor shifts in disturbance and tree longevity a distinctive record of fine charcoal occurs after 10 900 yr b p but not at any level prior to that time this shows that the forest was continously fire free for a very long time the charcoal is probably an indication of anthropogenic disturbance which may correlate with the spread of agricultural innovation in lowland new guinea an increase in secondary species after 7000 yr b p may be a result of minor anthropogenic activity or the result of warmer conditions and shorter tree life in the lower altitude forests

vegetation on the sunda shelf south china sea during the last glacial maximum pollen and phytoliths from sediment cores 5018300 18302 and 18323 on the continental shelf of the southern south china sea are analyzed with special attention to reconstructing vegetation and climate changes on the sunda shelf during the last glacial maximum lgm the lgm pollen assemblages are characterized by high percentages of pollen from the lowland rain forests and lower montane rainforests suggesting that the exposed shelf was covered with humid vegetation a marshy vegetation with plants of sedges reeds bamboo etc developed in the valley along the north sunda river and around the marshes were distributed palms and a variety of ferns including tree ferns cyathea the climate during the lgm inferred from the vegetation was cooler than that at the present day but no significant decrease in humidity was recorded at least the change was not sufficient to prevent the growth of rainforest finally the observed fluctuations in percentage of mangrove pollen are considered as a sensitive indicator of coastline migrations on the sunda shelf c 2009 elsevier b v all rights reserved

glacial and deglacial climatic patterns in australia and surrounding regions from 35 000 to 10 000 years ago reconstructed from terrestrial and near shore proxy data abstract this study forms part of a wider investigation of late quaternary environments in the southern hemisphere we here review the terrestrial and near shore proxy data from australia indonesia papua new guinea png new zealand and surrounding oceans during 35 10 ka an interval spanning the lead up to the last glacial maximum lgm the lgm proper 21 2 ka and the ensuing deglaciation sites selected for detailed discussion have a continuous or near continuous sedimentary record for this time interval a stratigraphically consistent chronology and one or more sources of proxy climatic data tropical australia indonesia and png had lgm mean annual temperatures 3 7 c below present values and summer precipitation reduced by at least 30 consistent with a weaker summer monsoon and a northward displacement of the intertropical convergence zone the summer monsoon was re established in northwest australia by 14 ka precipitation in northeast australia was reduced to less than 50 of present values until warmer and wetter conditions resumed at 17 16 ka followed by a second warmer wetter phase at 15 14 ka lgm temperatures were up to 8 c lower than today in mainland southeast australia and up to 4 c cooler in tasmania winter rainfall was much reduced throughout much of southern australia although periodic extreme flood events are evident in the fluvial record glacial advances in southeast australia are dated to 32 2 5 19 1 1 6 and 16 8 1 4 ka with periglacial activity concentrated towards 23 16 ka deglaciation was rapid in the snowy mountains which were ice free by 15 8 ka minimum effective precipitation in southern australia was from 14 to 12 ka in new zealand the glacial advances date to 28 21 5 and 19 ka with the onset of major cooling at 28 ka or well before the lgm there is no convincing evidence for a younger dryas cooling event in or around new zealand but there are signs of the antarctic cold reversal in and around new zealand and off southern australia there remain unresolved discrepancies between the climates inferred from pollen and those inferred from the beetle and chironomid fauna at a number of new zealand sites one explanation may be that pollen provides a generalised regional climatic signal in contrast to the finer local resolution offered by beetles and chironomids sea surface temperatures ssts were up to 5 c cooler during the lgm with rapid warming after 20 ka to attain present values by 15 ka the increase in summer monsoonal precipitation at or before 15 ka reflects higher insolation warmer ssts and steeper thermal gradients between land and sea the postglacial increase in winter rainfall in southern australia is probably related to the southward displacement of the westerlies as ssts around antarctica became warmer and the winter pack ice and antarctic convergence zone retreated to the south

palaeoenvironmental change in tropical australasia over the last 30 000 years a synthesis by the oz intimate group the tropics are the major source of heat and moisture for the australasian region determining the tropics response over time to changes in climate forcing mechanisms such as summer insolation and the effects of relative sea level on exposed continental shelves during the last glacial period is an ongoing process of re evaluation we present a synthesis of climate proxy data from tropical australasia spanning the last 30 000 years that incorporates deep sea core coral speleothem pollen charcoal and terrestrial sedimentary records today seasonal variability is governed largely by the annual migration of the inter tropical convergence zone itcz influencing this region most strongly during the austral summer however the position of the itcz has varied through time towards the end of marine isotope stage mis 3 conditions were far wetter throughout the region becoming drier first in the south universally cooler land and sea surface temperature sst were characteristic of the last glacial maximum with drier conditions than previously although episodic wet periods are noted in the fluvial records of northern australia the deglacial period saw warming first in the coral sea and then the indonesian seas with a pause in this trend around the time of the antarctic cold reversal c 14 5 ka coincident with the flooding of the sunda shelf wetter conditions occurred first in indonesia around 17 ka and northern australia after 14 ka the early holocene saw a peak in marine sst to the northwest and northeast of australia modern vegetation was first established on indonesia then progressively south and eastward to ne australia flores and the atherton tablelands show a dry period around 11 6 ka steadily becoming wetter through the early holocene the mid late holocene was punctuated by millennial scale variability associated with the el nino southern oscillation this is evident in the marine coral speleothem and pollen records of the region

late quaternary climate history of the horton plains central sri lanka abstract a 6 m long core was retrieved from a mire at ca 2200 m a s l in the horton plains national park central sri lanka the material collected consists of a mixture of organic matter and clastic particles which have been subject to bio litho and chronostratigraphic analyses the pollen spectra suggest semi arid conditions and a relatively species poor plant community from 24 000 until 18 500 cal yr bp associated with a weaker south west monsoon swm during the late pleistocene the climate was fluctuating between relatively dry and humid conditions as the result of changes in the monsoonal regime the onset of the moonson caused a semi humid climate resulting in an expansion of the upper montane rain forest umrf the strengthening of the swm was interrupted by two relatively dry climatic events each lasting ca 2000 years the early holocene was characterised by a per humid event followed by a hyper humid event both influenced by a further strengthening of the swm due to the orbitally induced maximum increment of summer insolation the middle holocene was marked by a trend towards semi arid climatic conditions during the late holocene the swm rains strengthened again

relationship of environmental changes in central sri lanka to possible prehistoric land use and climate changes abstract a radiocarbon dated pollen analysed peat sequence from the horton plains 2000 m a s l in central sri lanka together with physical and chemical parameters organic carbon mineral magnetics carbon isotopes and phytoliths indicates major environmental changes during the last 24 000 years the results suggest that a mobile life form i e a hunter forage culture predominated in an open landscape associated with xerophytic vegetation e g chenopodium spp at 17 5 ka bp incipient management of cereal plants and slash and burn techniques seem to have prevailed between 17 5 and 13 ka bp which was indigenous and associated with grazing evidence of systematic cereal cultivation in the form of oat and barley pollen grains is found from the late pleistocene 13 ka bp this is the earliest evidence of farming activities noted in sri lanka as well as in south asia after 13 ka bp cereal cultivation was associated with an increase in humidity with a later abrupt increase in aridity agricultural land use decreased from 8 to 3 6 ka bp when the area appears to have been almost deserted after a severe middle holocene arid phase i e 5 4 3 6 ka bp the agricultural activity with a limited extension was again initiated by 2 9 ka bp during the next 900 years cultivation ceased allowing the upper montane rain forest to dominate between 0 2 and 0 15 ka bp new phases of agricultural activities were undertaken and potato cultivation took place lately between 1950 and 1969 ad

amazon diversity in light of the paleoecological record abstract disjunct distributions of amazonian species have been explained previously by a refugial theory which postulates that amazonian rain forest was preserved in large highland regions throughout the pleistocene no direct radiocarbon dated evidence exists for the last glacial maximum with which to test this theory the only radiocarbon dates of pleistocene age from the amazon basin are of fossiliferous deposits in the proposed napo refugium of the west where both pollen assemblages and wood samples indicate that forest with cool andean elements existed there at two intervals in the last cycle of northern hemisphere glaciation implying a temperature depression of at least 4 c in the amazon lowlands under modern climatic conditions lateral erosion by river meander together with surface erosion serves as a rejuvenating mechanism for the rain forests of peru and ecuador the instability of late holocene amazonian climates is demonstrated by documenting a precipitation event in the eastern andean cordillera that caused widespread flooding of western amazonian forests 800 1300 bp late holocene pollen histories from widely dispersed parts of central amazonia distinguish between vegetation histories in the drainage of northern south western and western watersheds but all show histories of fluctuating intensities of dry seasons radiocarbon dating of charcoal layers in soils of venezuelan amazonia demonstrates the apparently random incidence of wild fires at wide intervals over at least the last 6 ka the high species richness of amazonia is a result of numerous opportunities for vicariance because of a very large total area wide variety of habitats and intermediate levels of disturbance particularly by hydrological processes that has varied on timescales from years to millennia amazonian disjunct distributions probably reflect regional environmental discontinuities in both interglacial and glacial times

late quaternary vegetation and climate change in the amazon basin based on a 50 000 year pollen record from the amazon fan odp site 932 hemipelagic sediments from the amazon deep sea fan odp site 932 5 12 7 n 47 1 8 w and continental shelf provide a 50 000 yr long pollen record of amazon basin vegetation the age model for hole 932a is constrained by eight magnetic remanence intensity features one paleomagnetic excursion and three ams14c dates alchornea melastomataceae myrtaceae and moraceae urticaceae are dominant taxa in the pollen record between 40 200 and 19 800 cal yr b p andean taxa such aspodocarpusandhedyosmum increase in abundance between 19 800 and 11 000 cal yr b p and prior to 40 200 cal yr b p the holocene pollen assemblage derived from amazon river and continental shelf sediments is dominated by secondary growth taxa such ascecropia climatic factors influencing the development of glacial and interglacial tropical vegetation are considered by comparing marine with terrestrial records of vegetation change this comparison shows that the amazon basin forests were not extensively replaced by savanna vegetation during the glacial period contradicting the refugia hypothesis

pereletki and the initiation of glaciation in siberia abstract modern glaciers present in northern siberia adjacent to the arctic ocean littoral develop through the gradual accumulation of windblown snow and firn in river valleys and other depressions such snow glaciers pereletki are largely ephemeral in nature and produce landscapes dominated by nivation hollows and other snow related landforms deposits associated with pereletki include nival nival solifluctionary and fluvio nival units the modern pereletki are considered to represent an initial form of glaciation and their development can be regarded as an analogue for the formation of nival deposits commonly attributed to a more extensive sartanian glacial event late quaternary glacial events in siberia involved both alpine and piedmont glaciation and widespread development of pereletki in lowland areas distinguishing between features and sediments produced by glacial ice and those attributable to ephemeral pereletki is necessary for accurate assessment of late quaternary glaciation in siberia

late quaternary sedimentation history of the lena delta abstract core and outcrop analysis from lena mouth deposits have been used to reconstruct the late quaternary sedimentation history of the lena delta sediment properties heavy mineral composition grain size characteristics organic carbon content and age determinations 14c ams and ir osl are applied to discriminate the main sedimentary units of the three major geomorphic terraces which form the delta the development of the terraces is controlled by complex interactions among the following four factors 1 channel migration according to the distribution of 14c and ir osl age determinations of lena mouth sediments the major river runoff direction shifted from the west during marine isotope stages 5 3 third terrace deposits towards the northwest during marine isotope stage 2 and transition to stage 1 second terrace to the northeast and east during the holocene first terrace deposits 2 eustasy sea level rise from last glacial lowstand to the modern sea level position reached at 6 5 ka bp resulted in back filling and flooding of the palaeovalleys 3 neotectonics the extension of the arctic mid ocean ridge into the laptev sea shelf acted as a halfgraben showing dilatation movements with different subsidence rates from the continent side differential neotectonics with uplift and transpression in the siberian coast ridges are active both likely have influenced river behavior by providing sites for preservation with uplift in particular allowing accumulation of deposits in the second terrace in the western sector the actual delta setting comprises only the eastern sector of the lena delta 4 peat formation polygenetic formation of ice rich peaty sand ice complex was most extensive 7 11 m in thickness in the southern part of the delta area between 43 and 14 ka bp third terrace deposits in recent times alluvial peat 5 6 m in thickness is accumulated on top of the deltaic sequences in the eastern sector first terrace

late quaternary vegetation change in the tari basin papua new guinea the changes in late quaternary vegetation at two sites in the tari basin central highlands of new guinea are presented haeapugua basin 1650 m altitude and tugupugua basin 2300 m altitude lie within the lower montane forest belt where the climate is characterised by high relative humidity and low seasonality pollen analysis mineral magnetics carbonised particle analysis and dating by radiocarbon and thermoluminescence techniques are employed to reconstruct the vegetation and sediment history the sequences include fragmentary interglacial interstadial records from before 50 000 yr b p and a continuous record from at least 28 000 yr b p to the present the study shows that prior to 21 000 yr b p vegetation in the basin was dominated by fluctuating proportions of tree taxa indicative of a forested environment the montane forest taxon nothofagus is important throughout the record although other tree taxa including castanopsis myrtaceae dacrydium and pandanus attain dominance at different times under the influence of a range of environmental factors the creation of an open environment around 21 000 yr b p is considered to be a consequence of the arrival of humans in the region the late glacial transition between 14 500 and 8500 yr b p is a period of climatic instability with landscape and vegetation adjustments proceeding at different rates across the highlands vegetational adjustments match modern ranges by about 8500 yr b p when swamp forest developed across the sites at the lower altitude site there are indications of anthropogenic forest disturbance associated with swamp forest clearance commencing around 1700 yr b p and intensifying through to the present forest clearance is recorded only after 700 yr b p at the higher site where agriculture was probably only sustainable after the introduction of sweet potato ipomoea batatas

the response of geomorphic systems to climatic and hydrological change during the late glacial and early holocene in the humid and sub humid tropics

late pleistocene and holocene development of the interior peat accumulating basin of tropical tasek bera peninsular malaysia the stratigraphy of holocene peat deposits from an interior lowland basin of tropical peninsular malaysia provides insight into the hydrological ecological and climatic controls on tropical peatland development interpretations about vegetation and climate dynamics including storm intensity over the past 5000 years are integrated with regional and global climatic and eustatic changes to serve as a proxy for past ecology and climate tasek bera basin tbb is a lowland dendritic basin in tropical peninsular malaysia accumulation of organic matter occurred in local lakes during the last glacial maximum lgm but widespread peat deposition did not start until 5300 bp when climatic changes led to the evolution of a wetland system peat accumulation progressively expanded with terrestrialisation of channels and subbasins to paludification of the riparian part of the lowland forest zone lithofacies can be distinguished despite the highly diverse peat and organic rich sediment composition as a result of the climatic and hydrologic changes over the past 5300 years peat accumulation rates ranging from 0 7 to 2 5 mm year are highest in pandanaceae environments and lowest in high ash swamp forests and environments dominated by cyperaceae transects of peat cores across the mire system show the stratigraphic complexities of the peat is the result of hydrological variations and thus plant successional changes ash yield shows that periods of high mineral matter input into the drainage system occurred since the mid holocene indicating rapid and cyclic changes in frequency and magnitude of runoff events and by inference storms stratigraphic analysis of peat and ash yield are tools that provide a proxy for development of holocene hydrologic events in topogenous peat deposits

enigmatic origin of ferruginous coprolites evidence from the miocene wilkes formation southwestern washington excrement shaped masses of siderite and limonite have been reported from clay rich sedimentary rocks that range in age from late permian to holocene these objects have been widely accepted as being coprolites but the ferruginous composition absence of internal inclusions and scarcity of associated vertebrate remains suggest that they may instead be pseudofossils created by mechanical deformation of plastic sediment possible abiotic mechanisms include coseismic liquefaction intrusion of sediment into hollow logs or expulsion of sediment in response to gravity alternatively carbon stable isotope ratios indicate that sediment extrusion may have been related to emission of biogenic methane during early stages of diagenesis

quantitative estimates of full glacial temperatures in equatorial africa from palynological data this paper presents a new reconstruction of the mean annual temperature obtained from a high altitude pollen sequence in equatorial africa 3 28 s 29 34 e 2240 m it has been achieved with an extended modern african reference data set by adding spectra from 228 new sites and using another selection for pollen taxa the purpose of this paper is to test how the obtained temperature value depends upon the availability of modern analogues the results are in good agreement with those previously published reinforcing the validity of the method the mean standard error is reduced by 0 3 c the mean temperature for the holocene appears 1 4 c warmer than the present and the last glacial maximum 25 18 kyrs bp cooling is better specified at 3 1 9 c a conservative value more consistent with reconstructed sea surface temperature in the equatorial ocean

biomass burning in indonesia and papua new guinea natural and human induced fire events in the fossil record abstract microscopic charcoal preserved in sediments from ten wetlands in the indonesian and papua new guinea region provide a proxy record of regional fire events during the last 20 000 years two periods of high regional charcoal frequency are encountered during the last glacial transition 17 000 9000 years b p and the middle to late holocene 5000 years b p to the present despite the presence of humans in the region throughout the last 20 000 years there is no suggestion that on a regional spatial scale fire frequencies were solely related to changing subsistence patterns of the human population pollen data from these same sites suggest that during times of high charcoal the rate at which vegetation changes represented by the fossil pollen spectra also increases high climate variability may promote a greater community turnover rate and in turn a more fire susceptible forest community rapid climate change and high variability during the last glacial transition and intensification of el nino related climate variability during the middle to late holocene may have been important mechanisms for promoting fire in rainforest environments and maintaining diversity of tropical rain forests

the vegetation and climate at the last glaciation on the emerged continental shelf of the south china sea studies on the dispersal mechanism and source areas of pollen from hemipelagic sediments recovered from the continental slopes of the south china sea scs reveal that vegetation existed on the exposed shelves at the last glacial maximum lgm and the latter part of the marine isotope stage 3 at the low sea level stand artemisiadominated grassland covered the northern continental shelf and tropical lowland rainforest and mangroves grew on the southern shelf sunda land consequently the climate in the northern scs must have been much colder and drier during the last glacial period compared to the present sunda land experienced only a marginally lower temperature but was not drier than today the enhanced contrast between the northern and southern parts of the scs in vegetation and climate during the lgm may be ascribed at least partly to the strengthening of winter monsoon during the last glacial period 2000 elsevier science b v all rights reserved