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Late Holocene (late + holocene)
Terms modified by Late Holocene Selected AbstractsPalaeoeskimo site burial by solifluction: Periglacial geoarchaeology of the tayara site (KbFk-7), Qikirtaq Island, Nunavik (Canada)GEOARCHAEOLOGY: AN INTERNATIONAL JOURNAL, Issue 2 2008Dominique Todisco The geoarchaeological study of the Palaeoeskimo Tayara site on Qikirtaq Island (Nunavik) has led to a better understanding of archaeological site formation in the arctic periglacial environment. The surrounding geomorphology (extra-site) is characterized by fine-grained, low plastic and leached postglacial glaciomarine sediments that have been reworked by sheet-like solifluction. This process buried the northern part of the Tayara site with mean annual rates between 1.68 and 2.86 cm/yr over approximately 350 years (1330,980 yr B.P.). The physicochemical and mineralogical properties of the frost-susceptible glaciomarine sediments may explain their susceptibility to solifluction. This process was probably enhanced by longer thawing periods or warmer/moister summer months that induced active layer thickening or rapid soil thawing. The dates we obtained in the downstream valley show that solifluction occurred during short warm periods in the Late Holocene between ca. 1500 and 1000 yr B.P., after 1000 yr B.P. (or after 500 yr B.P.) and recently (90,60 yr B.P.). Our data provide insights on the site factors and climate factors that govern site burial by solifluction. Solifluction promoted the preservation of the three superposed archaeological levels in the Tayara site; however, the waterlogging of the site related to solifluction also likely caused the subsequent abandonment of the site by the Palaeoeskimo people. © 2008 Wiley Periodicals, Inc. [source] Preliminary soil micromorphology studies of landscape and occupation history at Tabon Cave, Palawan, PhilippinesGEOARCHAEOLOGY: AN INTERNATIONAL JOURNAL, Issue 7 2007Helen Lewis Preliminary soil micromorphology study of cultural sediments at Tabon Cave, Philippines, supports interpretations of sporadic occupation in the Paleolithic. The presence in some deposits of authigenic minerals potentially related to altered cultural materials, such as ash, needs further investigation. Later in the sequence there is a marked change in local depositional processes, with the onset of significant quartz sand deposition in layers dating from the Middle to Late Holocene. This could relate to beach development in the area. Future sedimentological study and dating would confirm this interpretation, which suggests that in appropriate settings, stratified cave sediments could be useful for the study of regional sea level rise. © 2007 Wiley Periodicals, Inc. [source] Stratigraphic and geochronological context of human habitation along the Galana River, KenyaGEOARCHAEOLOGY: AN INTERNATIONAL JOURNAL, Issue 7 2007David K. Wright Geoarchaeological investigations along the Galana River, eastern Kenya, document a pattern of channel aggradation and then degradation from the Middle to Late Holocene. Archaeological occupations at six sites in fluvial terraces along a ,100 km stretch of the Galana River in Tsavo East National Park correspond with fluvial aggradation beginning ca. 6000 years ago. Artifact analyses indicate that the inhabitants of these sites utilized ceramics and stone tools similar to Pastoral Neolithic traditions detected at other penecontemporaneous archaeological sites in East Africa and possessed domesticated cattle from ca. 3700 years ago. The site occupations that occur during this period have dense artifact concentrations of predominantly locally procured items. The Galana River incised after ca. 900 years ago and there is a noticeable paucity of archaeological material, reflecting more peripatetic lifestyles. This shift in settlement pattern may reflect a decrease in reliance on riverine food sources during the Late Holocene, with diminished riparian environments associated with channel incision. © 2007 Wiley Periodicals, Inc. [source] A Reassessment of the holocene stratigraphy of the Wadi Hasa Terrace and Hasa formation, JordanGEOARCHAEOLOGY: AN INTERNATIONAL JOURNAL, Issue 6 2007Joseph Schuldenrein Vita-Finzi's 1960s model for Mediterranean terrace evolution was once the basis for regional valley histories across much of the Levant. A revisit to the Hasa terrace, formerly considered Early to Middle Holocene in age, resulted in a revised chronostratigraphy. Sedimentological and geochemical analyses bolstered by radiocarbon dating indicate that valley floor construction began shortly after the end of the Middle Holocene, at least 2000 years later than initially proposed. An updated model for floodplain evolution proposes three discrete phases of accretion and alluvial plain formation. A weak cambic soil overprints the alluvium and suggests slightly moister climates than at present for much of the Late Holocene. This model is in accord with settlement data. Intensified uplands agropastoralism accelerated the erosion of slope soils that were recycled and deposited as alluvium across the valley floor. The valley floor sequences of the Hasa are analogous to alluvial chronologies for neighboring wadis of the eastern Jordan Rift and can be tied to key Middle and Late Holocene geomorphic events in the Dead Sea and the southwestern Levant. The data strongly indicate that alluvial fill histories after 1800 cal B.C. were anthropogenically driven, whereas Middle Holocene landscape changes were climatically and structurally triggered. © 2007 Wiley Periodicals, Inc. [source] Comparison of sedimentation and occupation histories inside and outside rock shelters, Keep-River region, northwestern AustraliaGEOARCHAEOLOGY: AN INTERNATIONAL JOURNAL, Issue 1 2006I.A.K. Ward This paper compares archaeological evidence of Aboriginal occupation inside rock shelters and outside in adjacent sand sheets, focusing on two locations in the Keep-River region, northwestern Australia. Luminescence and radiocarbon dating reveal that occupation sequences inside rock shelters are generally younger ( < 10,000 yr B.P.) than outside ( < 18,000 yr B.P.). Differences in occupation chronology and artifact assemblages inside and outside rock shelters result from depositional and postdepositional processes and shifts in site function. An increase in regional sedimentation rate from 10 cm/ka , 1 in the Pleistocene to 20 cm/ka , 1 in the Holocene may account for late buildup of sediments within rock shelters, increased artifact accumulation, and reduced postdepositional disturbance in some settings. More intense use of rock shelters in the Late Holocene is indicated from a change in hunting technology and greater production of rock art. The results indicate that some cultural interpretations might be flawed unless archaeological evidence from rock-shelter and open-site excavations is integrated. © 2006 Wiley Periodicals, Inc. [source] A case of multiple metastasis in Late Holocene hunter-gatherers from the Argentine Pampean regionINTERNATIONAL JOURNAL OF OSTEOARCHAEOLOGY, Issue 5 2008L. H. Luna Abstract Chenque I site is a prehistoric cemetery located in Lihué Calel National Park (La Pampa province) in the Western Pampean region of Argentina. Hunter-gatherer societies made use of this site during the Final Late Holocene for at least 700 years (1030,370,BP). Currently 41 burial structures have been excavated, and more than 150 individuals have been recovered. There is great variability in mortuary patterns at the site (simple, multiple, primary, secondary burials, and also a variant not previously observed in the region). The life-ways of this population have been investigated through the evaluation of several biological and cultural factors. Several pathological conditions have also been identified in this cemetery. Burial no. 12 contains a skeleton of an adult male that shows multiple pathological lesions, compatible with a neoplastic disease. These lesions have been analysed using several methodological strategies: macroscopic, radiological and microscopic. This is the first time that this kind of disease has been identified from a prehistoric burial in Argentina. In this paper the location and characteristics of the lesions are evaluated, and the different neoplastic diseases that could have produced them are discussed. Since the people buried in this cemetery belonged to highly mobile societies, a key issue is to infer the consequences that this disease would have had on the dynamics of the group in which this person lived, because of the gradual deterioration of his health and physical strength. Copyright © 2007 John Wiley & Sons, Ltd. [source] Diagnostic osteology and analysis of the Mid- to Late Holocene dynamics of shags and cormorants in Tierra del FuegoINTERNATIONAL JOURNAL OF OSTEOARCHAEOLOGY, Issue 2 2007D. Causey Abstract We present here illustrated characteristics and anatomical descriptions of features that can be used to discriminate between four common skeletal elements (i.e. humerus, coracoid, femur, tarsometatarsus) of the five species of shags and cormorants known to occur in southern South America. We also present a detailed study of their distribution and abundance from about 6000 years before present to historical times as revealed by identification of faunal material excavated earlier and by re-analysis of material published previously. Our results present a high-resolution examination of the avian resource base used by early human hunters, and provide a foundation for future studies on the palaeoavifauna of Tierra del Fuego during the Mid- to Late Holocene. On the broadest scales, species diversity of the Phalacrocoracidae is qualitatively stable over space and time, a pattern that is also reflected in the larger marine bird community. On a finer scale, however, our results indicate that the abundance and distribution of cormorants and shags in Mid- and Late Holocene zooarchaeological deposits varied in a complex manner through time. These patterns do not appear to be related to proximity effects of hunters to colonies, but to other factors possibly associated with environmental change. Copyright © 2006 John Wiley & Sons, Ltd. [source] Spatial patterns and evolutionary processes in southern South America: A study of dental morphometric variationAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 1 2010Valeria Bernal Abstract The purpose of this article is to examine the patterns of evolutionary relationships between human populations from the later Late Holocene (1,500,100 years BP) of southern South America on the basis of dental morphometric data. We tested the hypotheses that the variation observed in this region would be explained by the existence of populations with different phylogenetic origin or differential action of gene flow and genetic drift. In this study, we analyzed permanent teeth from 17 samples of male and female adult individuals from throughout southern South America. We measured mesiodistal and buccolingual diameters at the base of the crown, along the cement,enamel junction. The results of multiple regression analysis and a mantel correlogram indicate the existence of spatial structure in dental shape variation, as the D2 Mahalanobis distance between samples increases with increasing geographical distance between them. In addition, the correlation test results show a trend toward reduction of the internal variation of samples with increasing latitude. The detected pattern of dental variation agrees with the one expected as an outcome of founder serial effects related to an expansion of range during the initial occupation of southern South America. Am J Phys Anthropol, 2010. © 2009 Wiley-Liss, Inc. [source] Holocene Floral and Faunal Remains Revealed Concealed Neotectonic Disturbance (Saria Tal, Kumaun Himalaya, India)ACTA GEOLOGICA SINICA (ENGLISH EDITION), Issue 1 2010Asha GUPTA Abstract: Palynological and paleontological investigations supported by the radiocarbon dates of the lacustrine sediments of two profiles from the temperate lake Saria Tal, in Nairn Tal District, Kumaun Himalaya, have revealed the presence of a concealed fold at the region. The profile from bore cores represents the upper part of the Late Holocene and the profile from exposed sections from the Middle Holocene to the over middle part of the Late Holocene. The data generated from different investigations have uniformly indicated that the former profile represents normal superposition, while the latter represents the reverse order. The contemporary pollen as well as moüuscan zones of both profiles are situated at different elevations but consist of similar bioremains , indicating continuation of the same strata in two profiles. The presence of reverse order of superposition, continuation of the same strata in two profiles at different elevations, and the orientation of biozones, have indicated that the revealed folding is of syncline type. The present study has also given an idea about the origin of this lake. [source] Late Quaternary development of the southern sector of the Greenland Ice Sheet, with particular reference to the Qassimiut lobeBOREAS, Issue 4 2004ANKER WEIDICK The evolution of the southern Greenland Ice Sheet is interpreted from a synthesis of geological data and palaeoclimatic information provided by the ice-sheet cores. At the Last Glacial Maximum the ice margin would have been at the shelf break and the ice sheet was fringed by shelf ice. Virtually all of the present ice-free land was glaciated. The initial ice retreat was controlled by eustatic sea level rise and was mainly by calving. When temperatures increased, melt ablation led to further ice-margin retreat and areas at the outer coast and mountain tops were deglaciated. Retreat was interrupted by a readvance during the Neria stade that may correlate with the Younger Dryas cooling. The abrupt temperature rise at the Younger Dryas,Holocene transition led to a fast retreat of the ice margin, and after ,9 ka BP the ice sheet was smaller than at present. Expansion of the ice cover began in the Late Holocene, with a maximum generally during the Little Ice Age. The greatest changes in ice cover occurred in lowland areas, i.e. in the region of the Qassimiut lobe. The date of the historical maximum advance shows considerable spatial variability and varies between AD 1600 and the present. Local anomalous readvances are seen at possibly 7,8 ka and at c. 2 ka BP. A marked relative sea level rise is seen in the Late Holocene; this is believed to reflect a direct glacio-isostatic response to increasing ice load. [source] The role of Late Holocene climate variability in the expansion of yellow birch in the western Great Lakes regionDIVERSITY AND DISTRIBUTIONS, Issue 5 2002Stephen T. Jackson Abstract. Pollen records from the western Great Lakes region of North America show substantial increases in birch pollen percentages during the late Holocene. The vegetational and population dynamics underlying the birch increase have received little attention, in part because of the inability to discriminate among species of birch based on pollen morphology. We used analyses of pollen and plant macrofossils from four lakes in the Upper Peninsula of Michigan to document that the birch pollen increase represents a regional expansion of yellow birch (Betula alleghaniensis) populations, which was initiated c. 4500 years ago. Whether yellow birch invaded the region at this time or simply expanded from small, previously established populations is not clear, although it probably did not grow near our study sites before the expansion. The initial expansion occurred during an independently documented period of high moisture and high water levels in Lake Michigan. A subsequent expansion in yellow birch abundance and distribution occurred c. 3000 years ago, coinciding with a second period of increased moisture and high lake-levels. The yellow birch expansion may have been modulated by millennial-scale climate variability, with most rapid expansion occurring during relatively wet periods. [source] Sediment transmission and storage: the implications for reconstructing landform developmentEARTH SURFACE PROCESSES AND LANDFORMS, Issue 1 2010R. C. Chiverrell Abstract The late Holocene (last 3000 years) development of the lower Ribble valley (northwest England) displays evidence for a complex response to a sediment recharge event forced by land-use change induced increases in erosion and sediment delivery. The deposition of fluvial sediments during the late Holocene was restricted to a series of reaches or depocenters separated by zones with no sediment accumulation constrained by older glacial and fluvial terrain. Apparent reach-wide correlations of fluvial terraces break down under the scrutiny applied by comprehensive and extensive radiocarbon control. Bayesian testing of relative order models show that large-scale geomorphological changes, e.g. the progression from one terrace level to another, were time transgressive between different depocenters. The different histories of sediment delivery and storage are probably a function of local- and process-scale variations in these depocenters, and reflect (dis)connectivity relationships within a reach in propagating a basin-scale change (superslug) in the sediment regime. Disconnectivity in the depositional regime through a fluvial reach limits what we can reconstruct in terms of sediment budgets, but radiocarbon dating of multiple palaeochannels offers considerable potential for landform-based research to uncover rates of change within individual depocenters. Copyright © 2009 John Wiley & Sons, Ltd. [source] Stratigraphic investigations at Los Buchillones, a coastal Taino site in north-central CubaGEOARCHAEOLOGY: AN INTERNATIONAL JOURNAL, Issue 5 2006Matthew C. Peros The authors present stratigraphic data from Los Buchillones, a now submerged Taino village on the north coast of central Cuba that was occupied from some time prior to A.D. 1220 until 1640 or later. Los Buchillones is one of the best-preserved sites in the Caribbean, with material culture remains that include palm thatch and wooden structural elements from some of the more than 40 collapsed structures. The purpose of this study was to investigate the environment and site-formation processes of the Taino settlement. Sediment cores were sampled from the site and its vicinity to permit integration of the geological and archaeological stratigraphies. The cores were analyzed for color, texture, mollusk content, elemental geochemistry, and mineralogy. The results of the stratigraphic work are consistent with regional sealevel data that shows relative sea level has risen gradually during the late Holocene, but has remained relatively stable since the time the Taino first occupied Los Buchillones. Of the two structures partially cleared, at least one appears to have been built over the water, supported on pilings. Site selection is likely to have resulted from a consideration of environmental factors, such as access to marine, terrestrial, and lagoonal resources, and proximity to freshwater springs. © 2006 Wiley Periodicals, Inc. [source] Coastal paleogeography and human land use at Tecolote Canyon, southern California, U.S.A.GEOARCHAEOLOGY: AN INTERNATIONAL JOURNAL, Issue 2 2004René L. Vellanoweth A buried archaeological site at Tecolote Canyon provides an ideal case study for relating past human land use patterns to changes in coastal paleogeography. Postglacial sea level transgression, erosion, and other marine and fluvial processes form the context for examining two deeply buried archaeological components excavated at CA-SBA-72. Archaeological shellfish assemblages provide proxy data for evaluating the evolution of local marine environments. Pismo clams dominate shellfish assemblages dated to 5800 cal yr B.P., suggesting the presence of a broad and sandy, high-energy beach environment. At 5500 cal yr B.P., the almost exclusive use of California mussels by humans signals the development of rocky intertidal habitats. During the late Holocene, estuarine species dominate the marine mollusk assemblages at CA-SBA-72, reflecting the development of local estuarine conditions or trade with nearby Goleta Slough villages. The buried components at Tecolote Canyon appear to have served as temporary camps for shellfish harvesting and processing. While general changes in coastal paleogeography and human subsistence have been reconstructed for the Santa Barbara Coast, high resolution ecological data from Tecolote Canyon suggest that Native peoples also adapted to localized and shorter-term shifts in intertidal habitats, changes not evident in most larger or more disturbed surface sites in the region. Linking these changes with shifts in human land use patterns highlights the interaction between humans and a dynamic coastal system. These data demonstrate the importance of small, buried sites in understanding the full spectrum of human subsistence and settlement choices and local environmental change. © 2004 Wiley Periodicals, Inc. [source] Geoarchaeological insights gained from surficial geologic mapping, middle Moche Valley, PeruGEOARCHAEOLOGY: AN INTERNATIONAL JOURNAL, Issue 5 2003Gary Huckleberry We present the results of detailed surficial geologic mapping for a 10 km2 area of alluvial (quebrada) deposits located in the middle Moche Valley of Peru, where archaeological features and deposits provide cross-cutting relationships and numerical age control for late Holocene erosion and deposition associated with El Niño. Despite surfaces containing clasts that are heavily pitted and cracked due to salt weathering, archaeological and 14C dates indicate that most quebrada landforms in the study area are late Holocene in age and may reflect enhanced alluviation associated with increased El Niño activity beginning ca. 6000 cal yr B.P. Our study provides criteria for correlative dating of other Holocene landforms in the Moche Valley area but urges caution in long-distance (>100 km) correlation because of geographic variability in surface weathering. Surficial geologic mapping aided by archaeological age control allows improved understanding of the rates of landscape change important to the development of complex irrigation-based societies in the Peruvian Desert. © 2003 Wiley Periodicals, Inc. [source] The hidden record: Late Holocene landscapes and settlement archaeology in the Lower Ohio River ValleyGEOARCHAEOLOGY: AN INTERNATIONAL JOURNAL, Issue 2 2002C. Russell Stafford From extensive backhoe trenching and coring in the Great Miami,Ohio River confluence region, in conjunction with a large suite of radiocarbon ages, we have identified large tracts of late Holocene alluvium. Thick blankets of Historic alluvium (post-settlement) may also cover levees of the Ohio River. In conjunction with other studies in the Outer Bluegrass Region of the lower Ohio River valley, it is possible to document an association between floodplain Mollisols, Inceptisols, and Entisols and late Holocene-aged landforms. Levees appear to have stabilized between 1000 and 2000 yr B.P. Although buried soils are rare, archaeological materials were ubiquitous in late Holocene Landform Sediment Assemblages. Because a substantial volume of valley fill is late Holocene in age, Woodland sites of all types are frequently buried, and Fort Ancient sites may be buried by Historic alluvium. Therefore, if Woodland or later settlement studies in this region are based on surface evidence alone, they are likely to be biased. © 2002 John Wiley & Sons, Inc. [source] The effects of temporal and spatial patterns of Holocene erosion and alluviation on the archaeological record of the Central and Eastern Great Plains, U.S.A.GEOARCHAEOLOGY: AN INTERNATIONAL JOURNAL, Issue 2 2002E. Arthur Bettis III Patterns of erosion and deposition act as a filter that strongly influences the disposition of the archaeological record of the Central and Eastern Plains of the North American Midcontinent. Detailed studies of alluvial valley stratigraphy in four drainage basins in the region reveal temporal and spatial patterns of fluvial system behavior that control the preservation and visibility of past human activity. These basins are located on a 600-km-long longitudinal gradient extending from semiarid southwestern Kansas to moist-subhumid central Iowa. Despite significant environmental variability along this transect, basin-wide patterns of Holocene erosion and deposition are similar across the study area. From ca. 11,000 to 8000 yr B.P., aggradation, punctuated by slow alluviation and/or stability around 10,000 yr B.P., was the dominant process in large and some small valleys. The early and middle Holocene (ca. 8000,5000 yr B.P.) was a period of net erosion and sediment movement in small valleys, sediment storage in large valleys, and episodic aggradation on alluvial fans. During the late Holocene (post-5000 yr B.P.), alluvial fans stabilized, small valleys became zones of net sediment storage, and aggradation slowed in large valleys. Basin-wide aggradation followed by entrenchment and channel migration characterizes fluvial activity during the Historic period. Consideration of the effects of these temporal and spatial patterns of Holocene erosion and alluviation on the archaeological record is crucial for developing efficient cultural resource sampling strategies and for accurately interpreting the archaeological record. © 2002 John Wiley & Sons, Inc. [source] A study of Holocene floodplain particle size characteristics with special reference to palaeochannel infills from the upper Severn basin, Wales, UKGEOLOGICAL JOURNAL, Issue 2 2001Mark Patrick Taylor Abstract Multiple sedimentary units from floodplain reaches at Welshpool on the upper River Severn and at the confluence of the Afon Tanat and Afon Vyrnwy (mid-Wales, UK) were examined to ascertain if they have distinctive particle size characteristics. Changes in particle size characteristics and their possible relationship to known human and climatic impacts are also discussed. Ellipse plots of particle size characteristics from the River Severn floodplain at Welshpool show that coarse-grained outwash deposits can be clearly discriminated from channel margin or palaeochannel sediments. In contrast, at the Afon Tanat,Vyrnwy study reach, this discrimination is not seen so clearly. The relationships between age and particle size characteristics from the most sampled sedimentary environment, palaeochannel infills, were also examined. The data from the River Severn floodplain at Welshpool show that palaeochannel sediments reveal a gradual but clear increase in particle size from the mid- to late Holocene towards the present day. Sediments deposited in the period 90,160 years BP are markedly coarser. It is suggested that these changes may be related to the combined effect of land-use changes, metal mining impacts and changes in flood frequency and magnitude that occurred at this time within the upper Severn basin. In contrast, the particle size characteristics of post Late Devensian/Early Holocene units from Tanat,Vyrnwy palaeochannels were random with no discernible age,size patterns. It is suggested that the non-systematic grain size distribution may be due to the steeper valley gradients of the Tanat,Vyrnwy system (and by inference higher stream powers) and its relatively narrow valley form enabling more effective coupling between coarser outwash deposits found on and at the edges of hillslopes and the valley floor. Although the two study reaches have undergone comparable environmental change during the Holocene and lie in the piedmont zone of their catchments, palaeochannel units of the same age possess distinctly different characteristics. Intrinsic reach-scale geomorphic factors would appear to preclude the uniform application of particle size characteristics to determine alluvial response to environmental change. Consequently, care needs to be applied to the use of such data for environmental discrimination because the phenomenon of equifinality means that a specific set of sediment characteristics is not necessarily exclusive to specific fluvial environments in either space or time. Copyright © 2001 John Wiley & Sons, Ltd. [source] The millennial dynamics of a boreal forest stand from buried treesJOURNAL OF ECOLOGY, Issue 3 2004DOMINIQUE ARSENEAULT Summary 1We reconstructed the dynamics of a black spruce (Picea mariana) and jack pine (Pinus banksiana) forest stand in northern Québec using a continuous, 5200-year-long sequence of stem remains buried in adjacent peatland. Simulations of recruitment of such remains provided guidelines for inferring past ecosystem structure and composition at the stand scale. 2Compared with the late Holocene (4650,0 cal. year BP (CYBP)), the mid Holocene (5200,4650 CYBP) period was characterized by faster tree growth, larger stems and higher stem density, indicating higher forest productivity in association with a milder climate. 3The presence of stem remains of both species from 17 out of 20 contiguous 250-year time intervals suggests that the spruce-pine stand exhibited high compositional stability, with both species regenerating after fire from canopy-stored seed banks. 4Relative species abundance closely followed the duration of past fire intervals deduced from the number of tree rings in buried conifers. Time periods of long (4650,3950, 3400,1850 and 250,0 CYBP) and short fire intervals (4950,4650, 3950,3400 and 1850,250 CYBP) were associated, respectively, with decreasing and increasing pine abundance, probably reflecting faster juvenile growth, lower shade tolerance, earlier sexual maturity and shorter longevity in jack pine compared with black spruce. 5We conclude that both climate change and climate-induced fire disturbance have been driving long-term ecosystem dynamics. Our field evidence supports the idea that interactions between disturbances and the life-history traits of species modulate the impact of climate change at the scale of forest stands. At the same time, disturbances may result in long-term stability of disturbance-adapted ecosystems. [source] Hunter-gatherer response to late Holocene climatic variability in northern and central AustraliaJOURNAL OF QUATERNARY SCIENCE, Issue 6 2010Alan N. Williams Abstract Sum probability analysis of 1275 radiometric ages from 608 archaeological sites across northern and central Australia demonstrates a changing archaeological signature that can be closely correlated with climate variability over the last 2 ka. Results reveal a marked increase in archaeological records across northern and central Australia over the last 2 ka, with notable declines in western and northern Australia between ca. AD 700 and 1000 and post-AD 1500 , two periods broadly coeval with the Medieval Climatic Anomaly and the Little Ice Age as they have been documented in the Asia,Pacific region. Latitudinal and longitudinal analysis of the dataset suggests the increase in archaeological footprint was continent wide, while the declines were greatest from 9 to 20° S, 110 to 135° E and 143 to 150° E. The change in the archaeological data suggests that, combined with an increase in population over the late Holocene, a disruption or reorganisation of pre-European resource systems occurred across Australia between ca. AD 700 and 1000 and post-AD 1500. These archaeological responses can be broadly correlated with transitions of the El Niño,Southern Oscillation (ENSO) mean state on a multi-decadal to centennial timescale. The latter involve a shift towards the La Niña-like mean state with wetter conditions in the Australian region between AD 700 and 1150. A transition period in ENSO mean state occurred across Australia during AD 1150,1300, with persistent El Niño-like and drier conditions to ca. AD 1500, and increasing ENSO variability post-AD 1500 to the present. Copyright © 2010 John Wiley & Sons, Ltd. [source] Fire and vegetation history on Santa Rosa Island, Channel Islands, and long-term environmental change in southern California,JOURNAL OF QUATERNARY SCIENCE, Issue 5 2010R. Scott Anderson Abstract The long-term history of vegetation and fire was investigated at two locations , Soledad Pond (275,m; from ca. 12 000,cal. a BP) and Abalone Rocks Marsh (0,m; from ca. 7000,cal. a BP) , on Santa Rosa Island, situated off the coast of southern California. A coastal conifer forest covered highlands of Santa Rosa during the last glacial, but by ca. 11 800,cal. a BP Pinus stands, coastal sage scrub and grassland replaced the forest as the climate warmed. The early Holocene became increasingly drier, particularly after ca. 9150,cal. a BP, as the pond dried frequently, and coastal sage scrub covered the nearby hillslopes. By ca. 6900,cal. a BP grasslands recovered at both sites. Pollen of wetland plants became prominent at Soledad Pond after ca. 4500,cal. a BP, and at Abalone Rocks Marsh after ca. 3465,cal. a BP. Diatoms suggest freshening of the Abalone Rocks Marsh somewhat later, probably by additional runoff from the highlands. Introduction of non-native species by ranchers occurred subsequent to AD 1850. Charcoal influx is high early in the record, but declines during the early Holocene when minimal biomass suggests extended drought. A general increase occurs after ca. 7000,cal. a BP, and especially after ca. 4500,cal. a BP. The Holocene pattern closely resembles population levels constructed from the archaeological record, and suggests a potential influence by humans on the fire regime of the islands, particularly during the late Holocene. Copyright © 2009 John Wiley & Sons, Ltd. [source] Late Pleistocene and Holocene glaciation of the Fish Lake valley, northeastern Alaska Range, Alaska,JOURNAL OF QUATERNARY SCIENCE, Issue 7 2009Nicolás E. Young Abstract We reconstructed a chronology of glaciation spanning from the Late Pleistocene through the late Holocene for Fish Lake valley in the north-eastern Alaska Range using 10Be surface exposure dating and lichenometry. After it attained its maximum late Wisconsin extent, the Fish Lake valley glacier began to retreat ca. 16.5,ka, and then experienced a readvance or standstill at 11.6,±,0.3,ka. Evidence of the earliest Holocene glacial activity in the valley is a moraine immediately in front of Little Ice Age (LIA) moraines and is dated to 3.3,3.0,ka. A subsequent advance culminated at ca. AD 610,900 and several LIA moraine crests date to AD 1290, 1640, 1860 and 1910. Our results indicate that 10Be dating from high-elevation sites can be used to help constrain late Holocene glacial histories in Alaska, even when other dating techniques are unavailable. Close agreement between 10Be and lichenometric ages reveal that 10Be ages on late Holocene moraines may be as accurate as other dating methods. Copyright © 2009 John Wiley & Sons, Ltd. [source] Late Devensian and Holocene relative sea-level changes on the Isle of Skye, Scotland, UK,JOURNAL OF QUATERNARY SCIENCE, Issue 2 2007Katherine A. Selby Abstract Detailed litho- and biostratigraphical analyses from three coastal sites in contrasting coastal settings on the Isle of Skye, Scotland, UK, reveal evidence for several changes in relative sea level during the Late Devensian and Holocene. At the start of the record, relative sea level in the area was high at ca. 12,500 14C (ca. 14,800,cal.) yr,BP but then fell, reaching a low point during the Younger Dryas, at ca. 11,000,10,000 14C (ca. 13,000,11,600,cal.) yr,BP, when a rock platform, correlated with the Main Rock Platform, was formed. In the early,middle Holocene, relative sea level was rising by ca. 8000 14C (ca. 8800,cal.) yr,BP and in northeast Skye a lagoonal surface, correlated with the Main Postglacial Shoreline, was formed at ca. 6600 14C (ca. 7500,cal.) yr,BP. By the late Holocene, relative sea level was again falling, but a rise, registered at at least two sites, began probably before ca. 4000 14C (ca. 4500,cal.) yr,BP, and a second lagoonal surface in northeast Skye, correlated with the Blairdrummond Shoreline, was formed, although by ca. 3000 14C (ca. 3200,cal.) yr,BP relative sea level in the area had resumed its downward trend. The pattern of relative sea-level changes disclosed is compared with evidence elsewhere in Scotland. Copyright © 2006 John Wiley & Sons, Ltd. [source] The Upper Pleistocene to Holocene sediments on the Mediterranean island of Lampedusa (Italy)JOURNAL OF QUATERNARY SCIENCE, Issue 6 2004C. Giraudi Abstract The island of Lampedusa lies on the northern edge of the African continental shelf, but during some Quaternary marine lowstands it was joined to the African continent. The study and dating of the aeolian, alluvial, detrital sediments, calcareous crusts and speleothems have established that the climatic,environmental variations recorded on the island can be related chronologically to those known for northern Libya, Tunisia and the Italian peninsula. During the Last Glacial Maximum, phases of Saharan dust accumulation on Lampedusa occurred, and were coeval with dust accumulation in crater lakes and on high mountains in central-southern Italy, and with phases of glacial advance in the Apennines and in the Alps. During the late Holocene, accumulation of Saharan dust on Lampedusa occurred but there was little accumulation of dust on the northern side of the Mediterranean Sea. With the new data from Lampedusa, it is possible to envisage two different scenarios of atmospheric circulation relating to the Last Glacial Maximum and to the late Holocene. During the Last Glacial Maximum, southerly atmospheric circulation brought rainfall to the southern slopes of the Alps and to the Apennines. During the late Holocene, a prevalent westerly atmospheric circulation became established in the northern Mediterranean. Copyright © 2004 John Wiley & Sons, Ltd. [source] Changing marine productivity off northern Chile during the past 19,000 years: a multivariable approachJOURNAL OF QUATERNARY SCIENCE, Issue 4 2004M. Mohtadi Abstract A multivariable approach utilising bulk sediment, planktonic Foraminifera and siliceous phytoplankton has been used to reconstruct rapid variations in palaeoproductivity in the Peru,Chile Current System off northern Chile for the past 19,000,cal.,yr. During the early deglaciation (19,000,16,000,cal.,yr,BP), our data point to strongest upwelling intensity and highest productivity of the past 19,000,cal.,yr. The late deglaciation (16,000,13,000,cal.,yr,BP) is characterised by a major change in the oceanographic setting, warmer water masses and weaker upwelling at the study site. Lowest productivity and weakest upwelling intensity are observed from the early to the middle Holocene (13,000,4000,cal.,yr,BP), and the beginning of the late Holocene (<4000,cal.,yr,BP) is marked by increasing productivity, mainly driven by silicate-producing organisms. Changes in the productivity and upwelling intensity in our record may have resulted from a large-scale compression and/or displacement of the South Pacific subtropical gyre during more productive periods, in line with a northward extension of the Antarctic Circumpolar Current and increased advection of Antarctic water masses with the Peru,Chile Current. The corresponding increase in hemispheric thermal gradient and wind stress induced stronger upwelling. During the periods of lower productivity, this scenario probably reversed. Copyright © 2004 John Wiley & Sons, Ltd. [source] A multiproxy record of Holocene environmental changes in the central Kola Peninsula, northwest RussiaJOURNAL OF QUATERNARY SCIENCE, Issue 4 2002Nadia Solovieva Abstract A sediment core from Chuna Lake (Kola Peninsula, northwest Russia) was studied for pollen, diatoms and sediment chemistry in order to infer post-glacial environmental changes and to investigate responses of the lake ecosystem to these changes. The past pH and dissolved organic carbon (DOC) of the lake were inferred using diatom-based transfer functions. Between 9000 and 4200 cal. yr BP, slow natural acidification and major changes in the diatom flora occurred in Chuna Lake. These correlated with changes in regional pollen, the arrival of trees in the catchment, changes in erosion, sediment organic content and DOC. During the past 4200 yr diatom-based proxies showed no clear response to changes in vegetation and erosion, as autochthonous ecological processes became more important than external climate influences during the late Holocene. The pollen stratigraphy reflects the major climate patterns of the central Kola Peninsula during the Holocene, i.e. a climate optimum between 9000 and 5400/5000 cal. yr BP when climate was warm and dry, and gradual climate cooling and an increase in moisture during the past 5400/5000 yr. This agrees with the occurrence of the north,south humidity gradient in Fennoscandia during the Holocene. Copyright © 2002 John Wiley & Sons, Ltd. [source] Palaeoclimate signals as inferred from stable-isotope composition of ground ice in the Verkhoyansk foreland, Central YakutiaPERMAFROST AND PERIGLACIAL PROCESSES, Issue 2 2006Steffen Popp Abstract Ice-rich permafrost deposits and their isotopic composition were studied at four sites in the western foreland of the Verkhoyansk Mountains, Central Yakutia. The isotopic composition of ice wedges formed in alluvial and loess-like sediments generally reflects the palaeoclimate of winter conditions. The middle Weichselian Ice Complex developed around 41,ka,14C BP during a period with colder winters than today. Similarly severe conditions are reflected in the late Weichselian Ice Complex from around 20,ka to 13,ka,14C BP. The transition to the Holocene is characterised by increases of 5, and 35, in ,18O and ,D, respectively. This warming is documented in wedge ice, which grew between 8.5 and 4.5,ka BP. Towards the late Holocene and sub-recent times, a climatic deterioration is recorded, reflected by lighter isotopic composition of ice wedges, which developed between 1.2,ka and 0.7,ka,14C BP. Copyright © 2006 John Wiley & Sons, Ltd. [source] Variation and causal factors of craniofacial robusticity in Patagonian hunter-gatherers from the late HoloceneAMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 6 2006Valeria Bernal Fueguian-Patagonian skulls have been characterized as some of the most robust of any modern crania. However, the causal factors of such robusticity remain unsettled. We assess within- and among-sample cranial robusticity of seven samples from continental Patagonia and Tierra del Fuego, using geometric morphometric techniques. In addition, the biomechanical, phylogenetic, and climatic hypotheses proposed to account for robusticity in such samples are discussed. Two Amerindian samples of farmers and two early middle Holocene samples from South America were included. The results show: 1) large variation in craniofacial robusticity among Patagonian samples, with the highest robusticity in samples from south continental Patagonia and Isla Grande of Tierra del Fuego, whereas central and north Patagonian samples display the same degree of robusticity as farmer samples; 2) that early middle Holocene samples display lower levels of robusticity than South Patagonian samples; and 3) strong association between latitude and craniofacial robusticity, with the most robust craniofacial morphologies occurring at the highest latitudes. In consequence, neither masticatory stress nor retention of ancestral features is supported by the morphological evidence analyzed. Hence it is hypothesized that endocrine changes related to cold climate may be a plausible explanation for several craniofacial features found in Fueguian and south continental Patagonian samples, such as their large masticatory component, and pronounced supraorbital ridge and glabellar region. Am. J. Hum. Biol. 18:748,765, 2006. © 2006 Wiley-Liss, Inc. [source] Role of wild plant foods among late Holocene hunter-gatherers from Central and North Patagonia (South America): An approach from dental evidenceAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 4 2007Valeria Bernal Abstract This study evaluates the role of plant foods in the subsistence of hunter-gatherers that inhabited the Central East, Northwest, and Northeast Patagonia (Argentina) during the late Holocene (ca. 3,000,500 years BP). The goal of the present study is to assess the temporal variation of dental caries ratio and wear rate in skeletal samples to ascertain if the biological information supports the dietary shift toward greater consumption of wild plant foods around 1,500 years BP, suggested by other types of evidence. The authors registered caries, antemortem and postmortem tooth loss, and tooth wear from eight samples belonging to hunter-gatherers from Patagonia for which chronological sequences from early late Holocene (ca. 3,000,1,500 years BP) up to final late Holocene (ca. 1,500,500 years BP) are available. The results indicate that caries percentages in Patagonian samples fall within the range established for hunter-gatherers but there are significant geographical differences. In addition, caries ratio does not change significantly through time, so the amount of carbohydrates consumed seems to have remained fairly constant since 3,000 years BP. In contrast, there is a marked temporal trend toward the reduction of wear rates in the three areas, suggesting a faster rate in early late Holocene than in final late Holocene. These results would reflect a change to less hard and/or abrasive diets in the final late Holocene, probably owing to differences in food processing methods employed. Am J Phys Anthropol, 2007. © 2007 Wiley-Liss, Inc. [source] Dynamics of North Patagonian rainforests from fine-resolution pollen, charcoal and tree-ring analysis, Chonos Archipelago, Southern ChileAUSTRAL ECOLOGY, Issue 4 2003JULIAN M. SZEICZ1 Abstract Fine-resolution palaeoecological and dendrochronological methods were used to investigate the impacts of climate change, and natural and anthropogenic disturbances on vegetation in the North Patagonian rainforest of southern Chile at decadal to century timescales during the late Holocene. A lake sediment mud-water interface core was collected from the northern Chonos Archipelago and analysed for pollen and charcoal. Dendrochronological analysis of tree cores collected from stands of Pilgerodendron uviferuni close to the lake site was incorporated into the study. The combined analysis showed that the present mosaic of vegetation types in this region is a function of environmental changes across a range of timescales: millennial climate change, more recent natural and anthropogenic disturbances, and possibly short-term climatic variations. Of particular interest is the spatiotemporal distribution of Pilgerodendron uviferuni dieback/burning in the Chonos Archipelago region. [source] | ||||||||||||||||