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This paper illustrates a detailed geomorphological map (scale 1:50,000) of the marine and transitional terraces (glacio-lacustrine to marine) and raised shorelines linked to Holocene glacio-eustasy and neo-tectonics in the northern area of the Brunswick Penìnsula (Chilean region of the Strait of Magellan). The mapped area is located in Tierra del Fuego between the Segunda Angostura and Seno Otway. This map is the result of geomorphological field survey data integrated with the interpretation of aerial photographs and remote sensing imagery. The survey has allowed the mapping of a sequence of terraces and raised shorelines to be completed. The sequence mainly consists of four orders of marine and glacio-lacustrine terraced deposits, with elevations ranging from 25 to 1 m above mean sea level. The map also presents other landforms and deposits, with their formation linked to littoral, fluvial, glacial and aeolian processes. [ABSTRACT FROM AUTHOR]

Mapping the spread of Austronesian languages and its associated Neolithic culture forms the backbone of the orthodox model of the Island Southeast Asian Neolithic. The linguistic thrust of the narratives has tended to reduce the importance and independence of the archaeological record. In this paper we investigate how archaeological evidence has been used to support linguistic interpretations. Our own fieldwork and analysis suggest that reliance on the Austronesian linguistic 'tree' and the associated monolithic cultural categories may mask considerable complexity and diversity in the archaeological record. [ABSTRACT FROM AUTHOR]

The geomorphology of a coastal landscape may reveal an indication of past shoreline configurations. The spatial arrangement of the preserved morphologies may further contain indications on the importance of the different key parameters influencing shoreline evolution over millennial timescales, such as palaeo sea-level position, longshore currents, energy gradients, and sediment supply. This paper presents the results and observations of a surveying and mapping study conducted for the island of Samsø at a scale of 1:75,000. The objective of the work is to support the interpretation of core sample data and to extract information on the factors determining the morpho-sedimentary development of moraine-embedded coastal lagoon systems during the Holocene. The map is based on an airborne LiDAR-derived high-resolution digital terrain model that is combined with spatial information on bathymetry, surface geology and other features from archived geodata and maps. [ABSTRACT FROM PUBLISHER]

This paper presents data on and discusses the degree of postglacial stability of the northern Canadian tree limit. Holocene climatic changes have been both directional and synchronous for this region, though deteriorations/ameliorations either (1) lagged from west to east, (2) were buffered by local geographic factors, or (3) were not registered in the fossil record owing to the inherent persistence of the vegetation at some sites. The present northern tree limit in eastern Canada is in equilibrium with the prevailing climate, with the tree populations successfully regenerating both sexually and vegetatively. These tree stands are still occupying their maximum Hypsithermal positions. In contrast, the tree limit, tree line, and intervening forest-tundra ecotone in central and western Canada are out of equilibrium with today's climate. These populations are not sexually regenerative and apparently became established during warmer climates where the tree line was north of its present position. As such, they are susceptible to destruction by further climatic deterioration or anthropogenic disruption. [ABSTRACT FROM AUTHOR]

We present a geomorphological map of the southwestern coast of Sardinia encompassing inland and offshore areas of the S’Omu e S’Orku Mesolithic site. The submerged area was documented by high-resolution multibeam bathymetry combined with Side-Scan Sonar data. The emerged coastal area was surveyed using Uncrewed Aerial Vehicle Remote Sensing and field surveys. The inland landforms were shaped by coastal, fluvial, and gravity-induced processes. Most of the submerged landforms appear be modeled in subaerial conditions during sea-level lowstands, and then sealed by the rising sea level. The coastal evolution has been characterized by the rapid cliff retreat facilitated intense linear erosion of watercourses, by debris flows, rockfalls and toppling. Geomorphological evidences of cliff retreat due to landslide was supported by a simplified analytic hydraulic model of the wavecliff interaction. These processes and the sea level rise canceled any possible Mesolithic settlement along the coast. The survival of the S’Omu e S’Orku site is only due to a protected morphological position and to the distance from the Early Holocene coastline. The dearth of coastal Early Holocene prehistoric sites is likely the outcome of the presented coastal dynamics. [ABSTRACT FROM AUTHOR]

This paper presents a simple analytical model for estimating rock glacier age by coupling the ratio of frontal advance to total rock glacier length and the ratio of debris volume in the rock glacier to present debris flux in the talus cone–rock glacier transition zone. The model was applied to two rock glaciers at Prins Karls Forland, Svalbard. By assuming volumetric debris contents in the deforming layer of the rock glacier of between 0.3 and 0.4, we obtained age estimates for the rock glaciers of between 12 ka and 24 ka. The corresponding average rockwall retreat rates are between 0.30 and 0.62 mm a-1. Considering the limitations of the model, we suggest a minimum age of 13 ka for the initiation of rock glacier development. Using this age, rockwall retreat rates for the seven rock glaciers investigated at Prins Karls Forland are between 0.13 and 0.64 m ka-1 (assuming the volumetric debris content for the whole rock glacier/talus cone is 0.35). The model requires further testing on other datasets, better field estimates of the debris content and depth of the deforming layer, and could also benefit from the inclusion of an unsteady debris supply function in order to refine age estimates. [ABSTRACT FROM AUTHOR]

In the southwest Yukon, valley walls mantled by talus and glacial deposits have been modified by a variety of catastrophic processes. Avalanches, landslides, mudflows, and retrogressive slope failures have been triggered by a variety of internal and external causes. These flow mechanisms produce a range of landforms in the paraglacial environment that dominate the landscape, particularly in the higher mountain zones. Models of rock glacier formation resulting from retrogressive slope failures, high hydrostatic pressures, and avalanche activity are proposed. [ABSTRACT FROM AUTHOR]

Tafí valley is an elongated tectonic basin of about 450 km2 located in NW Argentina in a mountainous frame of metamorphic and granitic Precambrian-Paleozoic rocks belonging to Sierras Pampeanas. This study presents the first detailed geomorphological map of the area. The most representative landforms date to the Lateglacial-Holocene, with four differentiating aggradative units separated by incision phases. Among these phases, it is possible to identify the units H1 (Lateglacial-Early and Middle Holocene) and H2 (Upper Holocene until ca. 600 cal BP). These units are composed of slopes, fluvial terraces, and alluvial fans, forming a coupled system. In some areas, this system is complemented with fluvioglacial and glacial landforms. More recent units (H3 and H4), together with active processes, contribute to the great variety of morphologies represented in the area. [ABSTRACT FROM AUTHOR]

We detail variations in the weight percent (wt%) of quartz, a proxy for drift ice, in fifteen marine sediment cores from the northwest, west, and southwest Iceland shelf throughout the past 10 cal ka BP. We present the first map of iceberg distributions in Iceland waters between 1983 and 2011 and a new compilation of sea-ice records in the century from 850 to 1950 CE. The wt% of quartz, determined by quantitative X-ray diffraction (qXRD) analysis, is used to evaluate changes in the importation of drift ice. Small wt% of quartz were added to milled basalt (0% quartz), and to a mixture of non-clay and clay minerals; the qXRD method replicated 0 percent quartz, while measured 1–3 percent quartz always resulted in a "presence" estimate. The outer sites in the northwest sector lie close to the average position of the sea-ice margin between 1870 and 1920 CE; the southwest shelf sites lie south of this limit. Transects of cores along the Húnaflói and Djúpáll troughs indicate that the traces of drift ice decrease rapidly landward from the outer sites. The cores from the west/southwest of Iceland have limited amounts of quartz, generally possibly limited incursions of drift ice. [ABSTRACT FROM AUTHOR]

A geomorphological cartography of the Cafayate depression (NW Argentina) at a scale of 1:20,000 is presented. The Main Map was made with satellite images from 2009 to 2016 and aerial photographs from various dates. The area was classified into three categories of geomorphological dynamics according the type of fluvio-aeolian interaction. Anastomosing channels and crevasse splays are dominant in the southern section of the Santa María River, while meandering channels develop in the northern section. Extensive dune fields interacting with fluvial deposits have developed in the central sector of the depression. The Main Map also reflects the main human features and can be used as a tool for preparing hazard maps. [ABSTRACT FROM AUTHOR]

The European Pollen Database (EPD) is a community effort to archive and make available pollen sequences from across the European continent. Pollen sequences provide records that may be used to infer past vegetation and vegetation change. We present here maps based on 828 sites from the EPD giving an overview of changes in postglacial pollen assemblages in Europe over the past 15,000 years. The maps show the distribution and abundance of 54 different pollen taxa at 500 year intervals, supported by new age-depth models and associated chronological uncertainty analysis. Results show the individualistic patterns of spread of different pollen taxa, and provide a standardized dataset for further analysis, defining a spatial context for the study of past plant and vegetation changes and other aspects of environmental history in Europe. [ABSTRACT FROM PUBLISHER]

The Julian Alps (in the southeastern European Alps, Italy and Slovenia) represent an important case study area for the study of small and very small maritime glaciers. High mean annual precipitation results in great snow accumulation during the winter, permitting the presence of ice bodies with the lowest Equilibrium Line Altitudes in the Alps. During the Little Ice Age (LIA) 19 small glaciers (<1 km2) existed, covering a total area of 2.4 km2. By 2012, the glacierized area had shrunk by 84% and only isolated glacierets and ice patches survived, each having a total area less than 0.5 km2. We present here a geomorphological and palaeoglaciological map of 8 sections of the Julian Alps related to the late Holocene distribution of glaciers, at a scale of 1:6000. Glacier topography during the LIA maximum was reconstructed on the basis of well-expressed geomorphological features together with historical archive data. The present-day distribution of ice bodies was inferred from orthophotos and 1 m resolution digital terrain models derived from airborne laser scanning. The past and present areal extent and surface morphology of glaciers permits calculation of volume loss since the LIA, which is estimated at 96%. [ABSTRACT FROM AUTHOR]

Three new species: Opalia (Pliciscala) flemingi (late Nukumaruan-early Castlecliffian, OIS 71-29?, Wanganui); Kuroshioturris putere (Opoitian-Waipipian, Westland and Hawke's Bay), Antimelatoma waimea (Kapitean-Opoitian, Westland); two new genera: Cryptofusus (Turbinellidae) for New Zealand species formerly referred to Pleia Finlay (Australian); Onoketoma (Conidae, Raphitominae) for 'Insolentia' solitaria King, bathyal Nukumaruan, Palliser Bay. Xymene (sensu stricto; separated again from Axymene, Xymenella and Zeatrophon) is useful biostratigraphically in near-shore facies: X. drewi (Hutton) (based on Marwick's lectotype), Mangapanian-late Nukumaruan; X. expansus (Hutton), late Nukumaruan-early Castlecliffian (to OIS 19); X. plebeius (Hutton), OIS 17-Recent. New fossil records from Pleistocene (OIS 7) deposits at Hokianga Harbour, Northland: Agnewia tritoniformis (Blainville), Hydatina physis (Linne), Philine tepikia Rudman. Other biostratigraphically useful species: Zeatrophon bonneti (Cossmann) (Nukumaruan-OIS 9; 7?); Aeneator delicatulus Powell, Buccinulum caudatum Powell (both OIS 25-19, 17?). New synonymy: Otahua Marwick, 1948 = Bedeva Iredale, 1936; Cominella (Eucominia) marlboroughensis Powell = C. elegantula (Finlay), Nukumaruan-Recent; Antiguraleus Powell, 1942=Propebela Iredale, 1918; Antiguraleus depressipirus (Beu) = Propebela ula (Watson); Oenopota Morch, 1853 is possibly an earlier name for Liracraea Odhner, 1924, but Liracraea is retained; Antimelatoma ahiparana and A. otagoensis of Powell = A. buchanani (Hutton); Tritonoturris Dall, 1924=Asperdaphne Hedley, 1922; most Australasian 'Asperdaphne' species are assigned to Pleurotomella Verrill. Taxonomy revised: Cirsotrema zelebori (Dunker); Opalia (Nodiscala) nympha (Hutton) (Mangapanian-Nukumaruan); Acirsa cookiana (Dell, 1956) (OIS 23-Recent); Cominella (Eucominia) incisa (Hutton), Nukumaruan, Hawke's Bay; Euthria pangoides (Beu), Waipipian; Iredalula striata (Hutton), Kapitean(?)-Castlecliffian (-OIS 11) distinguished from I. alticincta (Murdoch & Suter), Nukumaruan-Recent; Ponderia zealandica (Hutton) (OIS 13-Recent); Amalda (Baryspira) olsoni Beu, Nukumaruan; Kuroshioturris angustata (Powell), Mangapanian-Recent; Austrotoma aguayoi (Carcelles) (Recent, SW Atlantic); Struthiolariopsis ferrieri (Philippi), Cretaceous, Quiriquina, Chile (Conoidea); Mitrellatoma angustata (Hutton), Nukumaruan; Gymnobela gypsata (Watson), Recent, E New Zealand, removed from Paracomitas; Paracomitas protransenna (Marshall & Murdoch) (Nukumaruan), P. gemmea (Murdoch) (Castlecliffian) and P. augusta (Murdoch & Suter) (=P. augusta powelli Dell; Recent); Aoteadrillia wanganuiensis (Hutton) (=chordata Suter and many other synonyms; Nukumaruan-Recent), A. finlayi (Powell) and A. apicarinata (Marshall & Murdoch) (Nukumaruan); Bulla quoyii Gray (OIS 7-Recent); Bulla australis Ferussac, Atlantic,=B. mabillei Locard; Philippia lutea (Lamarck), Nukumaruan-Recent. [ABSTRACT FROM AUTHOR]

Three new species: Grandicrepidula hemispherica (Nukumaruan, S Hawke's Bay), Pelicaria granttaylori (Mangapanian-early Nukumaruan, Wanganui - Hawke's bay), Pelicaria arahura (Waipipian-early Mangapanian, Westland and Hawke's Bay). Drawings of marine species in Smith's (1874) three plates of New Zealand molluscan types are republished. Further Australian molluscs in Wanganui Basin: Sabia australis (Lamarck), Clanculus plebejus (Philippi), both early Nukumaruan. Further northern New Zealand mollusc in Wanganui Basin: Stephopoma roseum (Quoy & Gaimard), OIS 13, 9. Distinctive gastropods extinct at end Nukumaruan: Struthiolaria frazeri (Hutton), Taxonia suteri (Marwick). Taniella planisuturalis (Marwick) (Opoitian-Nukumaruan, southern NZ) and Trivia (Ellatrivia) zealandica (Kirk) (Nukumaruan, Hawke's Bay-Wanganui; Castlecliffian, North Canterbury) occur in Castlecliffian (OIS 15?) rocks at Whakatane. Cantharidella tessellata (A. Adams) and Risellopsis varia (Hutton), formerly Haweran, are recorded from Nukumaruan and Castlecliffian rocks, respectively. New fossil late Nukumaruan-early Castlecliffian records listed from Mikonui-1 offshore well, Westland, include Malluvium calcareum (Suter) and 10 other species. Other biostratigraphically useful gastropods: Calliostoma (Maurea) nukumaruense (Laws) (Mangapanian-OIS 17); Argobuccinum pustulosum (Lightfoot), Semicassis labiata (Perry) (both earliest in OIS 7). New synonymy: Zeacumantus perplexus (Marshall & Murdoch) = Z. lutulentus (Kiener); Pelicaria vermis (Martyn) = all named Nukumaruan-Recent forms (other than P. rugosa (Marwick) and P. granttaylori n. sp.); Trivia flora Marwick = T. zealandica Kirk. Taxonomy revised: Zelippistes benhami (Suter) (OIS 13 & 9 at Wanganui), distinguished from Lippistes and Separatista; Stiracolpus species, informally; Maoricrypta profunda (Hutton), Waipipian-early Castlecliffian (- OIS 19); M. radiata (Hutton) (= incurva Zittel, = hochetteriana Woods, = wilckensi Finlay), (Middle Miocene?) Tongaporutuan-Opoitian; Eunaticina cincta (Hutton), holotype illustrated. [ABSTRACT FROM AUTHOR]

Composition of pre-settlement vegetation communities in the semi-arid Central Otago lowlands has been one of New Zealand's longstanding ecological puzzles. Uncertainty is due largely to a paucity of fossil data. Here, we provide new evidence for pre-settlement vegetation in the region based on analyses of plant macrofossils from 15 late Pleistocene and Holocene lowland sites. The assemblages represent two habitat types: wooded or partially wooded intermontane basin-floor wetlands, and low forest and/or shrubland habitats in the Kawarau and Clutha River gorges. In both habitat types, plant communities appear to have been predominantly woody, with significant components of herbaceous dicotyledons but few grasses. Both habitats seem to have undergone major post-settlement vegetation transformation. Several presently common taxa were rare or absent before human settlement, but others (including threatened spring annuals), now rare or extinct in the region, were formerly more common. [ABSTRACT FROM AUTHOR]

Crawford Lake, Ontario, Canada (43°28.1' N, 79°56.9' W, 278 masl) has varved and AMS dated sediments containing fossil pollen that record native Iroquoian farming ca. AD 1268 to 1520. From before AD 1000 to 1268, bioturbating organisms caused poor varve preservation but since then, well-preserved varves and dung pellets reflect anoxic bottom water due to meromixis. The onset of varve preservation coincides with the occurrences of pollen grains of Zea (maize), Helianthus (sunflower), Phaseolus (bean), Cucurbita (squash) and Portulaca (purslane), and spores of Ustilago cf. maydis (maize smut). These pollen grains and spores are more abundant in pellets between varve laminae than in the surrounding sediment matrix. Analyses of DNA from five pellets demonstrate that they are dung from wild Canada geese (Branta canadensis). In the autumn, as geese foraged in Iroquoian fields, they inadvertently ingested pollen and spores before flying to the lake. There they roosted and cast the pollen-rich dung pellets, which became part of the sediment. This study demonstrates that birds, wild geese and perhaps ducks, can be important vectors of pollen to lake sediments located near agricultural settlements. [ABSTRACT FROM AUTHOR]

It is now well established that Precolumbian farmers of Mexico and Central America were responsible for widespread environmental degradation before the arrival of Europeans. Relatively little is known, however, of the chronology, severity, and exact geographic distribution of these anthropogenic landscape impacts. This article addresses questions of Holocene land use and anthropogenic environmental change in the upper Rio Paz Valley, El Salvador, before and after the arrival of the Spanish in the sixteenth century. A lacustrine sediment sequence from Chalchuapa records the impacts of prehistoric agriculturalists on a mid-elevation tropical watershed during the past 3700 years. The 9.72 m sediment core from Laguna Cuzcachapa contains unequivocal evidence for human manipulation of the landscape: high levels of maize and agricultural weed pollen, charcoal, magnetic susceptibility, and sediment flux. The abundance of maize pollen (>6 percent) even in the basal sediments of the core indicates that an intensive system of maize cultivation was well established in Chalchuapa by 3700 cal yr BP. Proxy indicators of human disturbance continue to exhibit high values from 3700 cal yr BP to the present, interrupted only by two hiatuses: one centered on the ca. AD 430 Tierra Blanca Joven eruption of the Ilopango volcano, and another during a period of population decimation following the arrival of Europeans in the early sixteenth century AD. The periods of greatest anthropogenic disturbance include ca. 3700–1600 cal yr BP (Preclassic/“Protoclassic”) and ca. 1350–1000 cal yr BP (Late Classic and Early Postclassic Periods). [ABSTRACT FROM AUTHOR]

New Zealand Plio-Pleistocene bivalves revised: Limopsis, oysters, Pecten, Mactra (Maorimactra), Oxyperas, Lutraria, Austrovenus, Barnea, Myadora. Recent Indo-West Pacific Lutraria species are reviewed; the Red Sea-East African species L. (Lutraria) turneri Jousseaume resembles L. grandis (Hutton) (adopted in place of the junior homonym L. solida Hutton). Six new species proposed: Saccella maxwelli (Nukumaruan-Recent; known previously as S. bellula (A. Adams)); Limopsis turnbulli (Castlecliffian, OIS 15-20, SW Fiordland); Mactra (Maorimactra) marwicki (late Nukumaruan); M. (Maorimactra) carteri (early Castlecliffian, OIS 45?-19); Paphies delta (early Castlecliffian, OIS 31?-17); Myadora fortecosta (Kapitean-Opoitian). Further Indo-West Pacific warm-water migrants to New Zealand: Chama ruderalis Lamarck (Kapitean-Nukumaruan; = C. huttoni Hector, = C. pittensis Marwick); Lutraria (Psammophila) vellai (Beu) (late Nukumaruan); probably the two New Zealand late Neogene Ctenoides species. Further temperate migrant from the Atlantic: Lutraria (Lutraria) grandis. New synonymy: Xenostrobus Wilson = Limnoperna Rochebrune; Pecten novaezelandiae (Reeve) = all other New Zealand Pecten names; Serratina eugonia (Suter) = S. charlottae (E. A. Smith); Oxyperas komakoensis (Carter) = O. elongata (Quoy & Gaimard); Austrovenus stutchburyi (Wood) varies clinally over New Zealand, = A. aucklandica Powell, = A. crassitesta Finlay; Dosinia (Austrodosinia) horrida Marwick = D. anus (Philippi) (Nukumaruan-Recent); Panopea wanganuica Powell = P. smithae Powell (Nukumaruan-Recent); Myadora stephaniae Carter = M. waitotarana Powell (Waipipian-Nukumaruan). Distinctive bivalves extinct at the end of Nukumaruan time: Glycymeris shrimptoni Marwick, Patro undatus (Hutton), Lutraria (Lutraria) grandis, L. (Psammophila) vellai, Paphies crassiformis (Marshall & Murdoch), Eumarcia plana Marwick, Dosinia (Raina) nukumaruensis Marwick, Myadora waitotarana. Ennucula Iredale is used for Cenozoic and Recent Nuculominae; the application of Leionucula Quenstedt is unclear. Saccostrea glomerata (Gould) is used in place of S. circumsuta (Gould). Protothaca crassicosta (Deshayes) (formerly Haweran-Recent) is recorded from Opoitian rocks. Pecten novaezelandiae appeared below Potaka Tephra (1.0 Ma) during OIS 29 or earlier in eastern New Zealand, but just above the Brunhes-Matuyama transition (0.78 Ma, early OIS 19) in Wanganui Basin. Oxyperas elongata and Barnea similis (Gray) changed anagenetically through late Miocene-Pleistocene time; earlier forms are conspecific with Recent ones. Tawera Marwick is restored as a genus. Purpurocardia Maxwell is compared with Glans Megerle von Muhlfeld and Glyptoactis Stewart, and all are retained. Limnoperna huttoni (Suter) became extinct during OIS 13, Barytellina crassidens Marwick during OIS 9 or younger. Pholadidea tridens (Gray) (OIS 23 & 5a) and Ostreola virescens (Angas, 1868) are recorded fossil. [ABSTRACT FROM AUTHOR]

Early archaeological investigations on the Tibetan Plateau concluded that this harsh, high-elevation environment was successfully colonized around 30,000 years ago. Genetic studies have tended to support this view on the assumption that the uniquely evolved physiological capacities seen among modern Tibetan populations required long-term exposure to high-elevation selective pressures. Archaeological evidence amassed over the last decade suggests, however, that colonization leading to full-time occupation occurred much later. Seasonal foraging forays into high-elevation settings at c . 30 and 15 cal. ka appear to have been limited ‘adaptive radiations’ coincident, respectively, with the appearance of early and late Upper Palaeolithic adaptations in low-elevation source areas around the plateau. More permanent occupation of the plateau probably did not begin before c . 8200 cal. bp and may have been driven by ‘competitive exclusion’ of late Upper Palaeolithic foragers from low-elevation environments by emerging settled agricultural groups. The appearance of specialized epi-Palaeolithic blade and bladelet technologies on the high plateau, after 8200 cal. ka, may indicate ‘directional selection’ impacting on these new full-time residents. An ‘adaptive radiation’ of agriculturalists into the mid-elevations of the plateau, this time leading to year-round occupation, is again seen after 6000 cal. bp. [ABSTRACT FROM AUTHOR]

Aboriginal fishing in south-western Australia was significantly affected by Late Holocene physical and biological changes along this region's 1,600km-long littoral. About 4000 BP sedimentological processes, in part generated by climatic factors, altered coastal configurations and estuarine hydrologies, blocking marine lagoons from the sea and causing partial filling and seasonal barring of estuary floors and entrances. These geomorphological changes affected most of the region's estuaries, and intensified seasonal differences in their salinity levels, which, combined with seasonal barring, restricted movements of school fish populations, thus compelling shifts in fishing strategies. Review of palaeogeographical and palaeontological data and investigation of former tidal weirs, on the shores of now nearly tideless estuaries and relict marine bodies, gives insight into the chronology of fishing and into the ways this key subsistence activity may have been adapted to changes in estuarine and coastal conditions. The Late Holocene may be the period when south-western Aboriginal fishing gained the economic and socio-political importance that it had regionally during the period of European settlement. [ABSTRACT FROM AUTHOR]

During recent decades, lake levels in the Yukon Flats region of interior Alaska have fluctuated dramatically. However, prior to recorded observations, no data are available to indicate if similar or more extreme variations occurred during past centuries and millennia. This study explores the history of Yukon Flats lake origins and lake levels for the past approximately 5,500 years from sediment analyses guided by previous work on permafrost extent, thermokarst, and modern isotope hydrology. Sediments dated by 210Pb and AMS radiocarbon indicate stable chronologies following initial lake initiation. Subsequent lithology is autochthonous, and oxygen isotope ratios of endogenic carbonate reflect lake level change at multiple time scales. Sediment results indicate high lake levels between approximately 4000 and 1850 cal yr BP, which is interpreted to reflect wetter-than-modern conditions. Lower lake levels with short-lived high stands during the past approximately 800 years reflect generally arid conditions with brief wet intervals similar to the region's moisture regime today. The millennial trend is one of increasing aridity and corresponds closely with fire reconstructions and regional paleoclimatic trends. We conclude that high-magnitude lake-level fluctuations and decadal scale trends occurred before the observational period and are persistent hydroclimatic features of the Yukon Flats region. [ABSTRACT FROM AUTHOR]