Abstract: In this paper we use a simulation approach to explore the effect of variation in taxon parameters and landscape patterning on relevant source area of pollen. We use the Prentice-Sugita model, assume constant atmospheric conditions and basin morphology, and take a reductionist approach to explore the behaviour of pollen dispersal and deposition in a simple landscape scenario. Individual factors within the scenario (pollen fall speed, relative pollen productivity, size of basic unit in the landscape mosaic, patch size, rarity of individual taxa and overall number of taxa present in the landscape) are varied while all other parameters are kept constant, thus permitting exploration of the role of different components of the system. These simulations suggest that, for basins of given size under fixed atmospheric conditions, the relevant source area of pollen is primarily an expression of the patterning of the different vegetation elements within the landscape. This has important implications for the interpretation of palaeoecological records and reconstruction of past environments. Reconstruction, especially quantitative reconstruction, requires some estimate of past relevant source area of pollen. If, as our results suggest, vegetation patterning is an important determinant of this, then it must also be taken into account when attempting to reconstruct past vegetation communities.

Abstract: Peatlands provide a widespread terrestrial archive of Holocene environmental change. The taphon omy of peat is relatively simple, the range of evidence and proxies is wide, and dating methods have become more accurate and precise, such that the potential temporal resolution of records is high. Although long estab lished, the use of peatlands as archives of Holocene change has undergone phases of decline and resurgence. Here, the variable exploitation of the peat archive is explored, and recent developments in peatland science as applied to Holocene records are reviewed with reference to the collection of papers in this Special Issue of The Holocene, which are arranged in four key themes: (1) records of Holocene climatic change; (2) peatland dynamics; (3) carbon accumulation; and (4) implications for conservation and management. The changing acceptance of peatlands as archives of Holocene climatic change is attributed to developments in understanding of the peatland system and geographical differences in the history of Holocene research. Recent developments in biological and geochemical proxies combined with improvements in chronological techniques have resulted in renewed interest in peatland palaeoclimate records. Peatlands are an important global carbon pool and it is clear that climate has influenced the efficiency of long-term carbon sequestration by these systems. Climate has also had an impact on the biodiversity and condition of peatlands, which creates problems in discerning cause and effect in sites affected by human activities, and in targeting remedial management. It is concluded that particular strengths of the archive are the current diversity of peat-based palaeoenvironmental research and the potential for multiproxy analyses to be applied to a range of research issues. Mire-based investigations can complement research in other realms, and are deserving of greater attention from researchers of other archives.

Abstract: An actively growing stalagmite collected from a cave located in the hills of the Western Ghats in the Uttar Kannada District of Karnataka, India, has been studied for stable isotope ratios of oxygen and carbon, width of growth layers and grey-level changes. Distinct carbonate layers, alternate coarse and compact, are seen in cross-section. Each couplet of compact and coarse layer is found to represent a single year. A total of 331 such couplets has been counted, indicating that the stalagmite started growing in AD 1666 and continued until it was sampled. Stable isotope ratios of oxygen (I´18O) and carbon (I´13C) show variations ranging from -13.6 to -7.9° and from -2.7 to 1.6°, respectively. We have reconstructed past rainfall changes of the cave site using the 'amount effect' in I´18O of rain. Speleothem I´18O and instrumental rainfall data from the associated climate subdivision show a significant correlation (r = -0.62, decadal average). Several sharp spikes of enrichment and depletion in 18O are indicative of the past deficiency and excess in rainfall. Most of the severe drought years recorded independently by meteorological observations are found registered in the stalagmite layers. During the 331-year-period, rainfall was highest at AD 1666 and lowest around AD 1900. The stalagmite-generated past rainfall record can serve as a reasonable proxy for testing monsoon models.

Abstract: An event stratigraphy of dune stability/instability phases has been reconstructed, using 22 radiocarbon and 13 luminescence dates, for six dunefields along the north coast of Northern Ireland. There is no evidence for dune development prior to ċ. 7000 cal. years BP, during the early-Holocene rapid rise in RSL, and only limited evidence for sand accumulation in association with the RSL maximum. Dunefield dates correspond to either the subsequent regressive phase or, later, the gradual transgressive phase of RSL history in the mid-and late Holocene. At these times accommodation space for dune development and sediment supply were maximized. Episodes of climatic deterioration, particularly at 3100–2400 cal. years BP and 650–50 cal. years BP (the‘Little Ice Age’) were marked by widespread dune instability. A similar coincidence in timing has been recorded for dune systems elsewhere in northwestern Europe and is generally attributed to an increased frequency of storms and storm surges associated with the climat...

Abstract: During the Lateglacial and early Holocene, abrupt, millennial-scale climatic variations are recorded in a wide range of high-resolution proxy records from marine and terrestrial archives in NW Europe. Our review of the evidence for these rapid climate events do not show an apparent link to possible forcing factors such as long-term, orbitally induced variations in solar radiation, short-term variations in solar activity as inferred from 14 C, atmospheric carbon dioxide concentration, or volcanic sulphate as recorded in the GISP2 ice-core record. There is, however, a remarkable degree of similarity with the number, duration and timing of episodes of increased e ux of fresh water to the north Atlantic and Arctic Oceans from the Laurentide ice sheet and from the Baltic ice lake in SW Sweden. These freshwater outburst events occurred when continental runoff from the Laurentide ice sheet was rerouted from the Mississippi River to the Hudson River, St Lawrence River, Hudson Strait and along the Mackenzie River to the Atlantic and Arctic Oceans, and when the Baltic ice lake in SW Sweden drained to Skagerrak. Periods of increased freshwater e ow to the North Atlantic and Arctic Oceans may thus provide a mechanism to explain the abrupt and signie cant Lateglacial and early- Holocene climate events in NW Europe. The idea that freshwater outbursts might drive abrupt climate events is not new, but previous work may have underestimated the extent of support from proxy data and overestimated the ine uence of the Laurentide ice sheet.

Abstract: Closely spaced sequences of accelerator mass spectrometer (AMS) 14 C dates of peat deposits display century-scale wiggles which can be e tted to the radiocarbon calibration curve. By wiggle-matching such sequences, high-precision calendar age chronologiescan be generated which show that changes in mire surface wetness during the Bronze Age/Iron Age transition (c. 850 cal. bc) and the 'Little Ice Age' (Wolf, Sporer, Maunder and Dalton Minima) occurred during periods of suddenly increasing atmospheric concentration of 14 C. Replicate evidence from peat-based proxy climate indicators in northwest Europe suggest these changes in climate may have been driven by temporary declines of solar activity. Carbon-accumulation rates of two raised peat bogs in the UK and Denmark record low values during the 'Little Ice Age' which ree ects reduced primary productivity of the peat-forming vegetation during these periods of climatic deterioration.

Abstract: Measurements of the two water stable isotopes (dD and d18O) along EPICA (European Project for Ice Coring in Antarctica) Dome C ice core are combined with simple isotopic modelling (distillation models) to reconstruct the variability of both the site temperature (East Antarctica) and the moisture source temperature (nowadays probably the subantarctic Indian Ocean). We discuss the difference between the reconstructed site and source temperature pro” les with respect to the initial isotopic data. We show that (i) the early-Holocene optimum appears” rst in Antarctica and 800 years later in the Southern Ocean, and (ii) during the last 5000 years, the site and source temperatures co-vary at the centennial timescale. An 833-year periodicity is observed only on deuterium and site temperature and therefore probably of local origin.

Abstract: Techniques for estimating tidal elevation and con” nement (proxy for salinity) using modern benthic foraminiferal census data from New Zealand harbours and lower-salinity estuaries are described and assessed for their utility for reconstructing the depositional settings of late-Holocene sequences. We describe a simple modern analogue technique for estimating tidal or subtidal elevation of Holocene fossil faunas, utilizing the modern data set most applicable to the Holocene setting (sheltered tidal harbours and inlets, or lower-salinity estuaries). Canonical correspondence analysis was used to extract a synthetic con” nement gradient from for aminiferal census data in transects down” ve New Zealand estuaries. This gradient was used to develop a New Zealand Con” nement Index that can be computed for New Zealand modern and Holocene estuarine and harbour samples based on their foraminiferal composition. The value of the method for estimating Holocene elevational and con” nement (palaeosalinity) histories was ...

Abstract: A tongue of very coarse rockslide debris that extends 1.25km downvalley below Beinn Alligin in NW Scotland has been variously interpreted as a glacier-cored rock glacier, landslide debris redistributed by glacier ice or an excess-runout landslide. Exposure dating with cosmogenic 10Be demonstrates that the the debris mass was emplaced at 3950±320 yr BP, and therefore was not associated with glacier ice. Calculations based on frictional considerations imply that the feature is an excess-runout rock avalanche (sturzstrom) deposit. The morphological characteristics of the deposit appear consistent with movement by grainflow or fragmental flow. Failure is inferred to reflect time-dependent paraglacial stress release and consequent propagation of an internal joint network, but may have been triggered by seismic activity. The late-Holocene age of failure implies persistence of the eŒects of paraglacial stress release over a time-scale of several millennia.

Abstract: A suite of analyses was performed on sediments accumulated duringthe last 10 700 years in Lake Spaime, a small, hydrologically open water body in the modern alpine tundra zone of the Scandes Moun- tains, west-central Sweden. The study aimed to evaluate (1) the nature of climate changes that forced the late-Holocene loweringof altitudinal tree limit in the region, the timingof which is known from prior stu- dies based on radiocarbon dating of subfossil wood, and (2) the impact of these vegetational changes on an aquatic ecosystem. Arboreal pollen and plant macrofossil data confirm the persistence of trees in the lake catchment at least from c. 9700 cal. BP until c. 3700 cal. BP. Although growing-season temperature is com- monly believed to be the dominant factor drivingboreal forest tree-limit variations in the reg ion, a chir- onomid-based reconstruction of mean July air temperature suggests that local deforestation during the late Holocene was not accompanied by a significant cooling. The tree-limit retreat was more likely caused by increasing effective moisture and declining length of the growing season. The ecohydrological response of Lake Spaime to this combination of climate and vegetational changes included a decline in primary pro- ductivity, as indicated by an abrupt decrease in sediment organic matter content, while associated increases in organic d 13 C, d 15 N and C=N point to diminished fluxes and altered balance of catchment- derived nutrients followingdeforestation. The decline in aquatic productivity is also marked by a distinct change in the mineral magnetic properties, from a high magnetic concentration assemblage dominated by fine-grained magnetite of biogenic origin to one dominated by background levels of coarse-grained detrital magnetite.

Abstract: The plant macrofossil records from three raised bogs from western and central Ireland and from Cumbria were compared to investigate variations in the character and timing of the fen-bog transition (FBT). Two modes of raised or ombrotrophic peat formation were recognized. In the first mode the transition develops through a sedge-fen stage directly to raised-bog lawn, maintaining a near surface water table throughout the FBT (Abbeyknockmoy Bog). The second mode is characterized by a switch from fen or reedswamp to a dry Eriophorum-dominated mire type, suggestive of low or unstable water tables (Mongan Bog and Bolton Fell Moss). Comparisons with the Holocene effective precipitation record suggest that the type of transition and its timing may be affected by the prevailing climate regime. All that is required for ombrotrophy is a separation of the growing peat surface from the influence of ground and surface waters. This separation may be achieved by rapid peat accumulation in a moist climate, the accumulation of decay-resistant Eriophorum vaginatum hummocks or by a lowering of the water table, leading to a 'perched peat bed'. In the latter two cases, a 'pseudo-raised bog' community often persists, laying down highly humified peat, until increased oceanicity enables Sphagnum to dominate.

Abstract: Anthropogenic induced soil erosion has occurred in the Mediterranean during historic and pre historic times, but precise timeframes for periods of past soil erosion are largely missing due to the lack of datable material and suitable dating methods. In this study, optical dating of colluvial sediments from the Phlious Basin, NE Peloponnese, Greece, was applied. The results show that soil erosion derived colluvium formed under a Mediterranean type climate can be successfully dated by optical stimulated luminescence (OSL), and a high-resolution chronology of Holocene soil erosion could be established. Colluvial formation occurred in the early Holocene, but increased distinctly in the seventh millennium, parallel with the onset of the Neolithic (the start of farming activities). Other periods of strong colluviation are the Middle and Late Bronze Age (second millennium), the Roman period (first century to sixth century) and the period since the sixteenth century. Rates of reduced colluviation occurred during ...

Abstract: The ideas behind peatland restoration and the utility of testate amoebae in informing such schemes are brie‘ y reviewed and discussed in the context of two lowland raised-mire sites in northwest En...

Abstract: Twelve definable cryptotephra layers younger than c. 8600cal. BP are reported from lacustrine core material taken from An Loch Mor, Inis Oirr, Aran Islands, western Ireland. The geochemistry of these shard layers, which represent more Holocene tephras than previously geochemically characterized from any European site outside the proximal volcanic influence of Italy or Iceland, is presented. Of these tephras, four may correlate with known Iceland-derived tephra horizons (Vo 1477, HI, Lairg A and H5); one appears to have two possible named correlatives (Hoy;‘Lairg B’ at Sluggan Bog, N Ireland); another has a plausible correlative (AD 860A); but two others represent Icelandic tephras apparently not previously reported on Iceland itself, including a tephra that has geochemistry very similar to Hl (AD 1104) but which dates to c. cal. AD 840. Four tephras that date from the period c. AD 40-1400 have a distinct geochemical signature that relates to Jan Mayen, 750km to the northeast of Iceland and some 1800km distant from An Loch Mor. The results contribute substantially to the chronology of the sediments from An Loch Mor and, at the international level, to the tephrostratigraphy of the northeast Atlantic region. The well-attested Icelandic H4 tephra (from a Hekla eruption of c. 4260cal. BP) was not recorded; it is suggested that An Loch Mor lies south of its recordable distribution in this part of the northeast Atlantic region. Taken together with work at other sites, the findings point to a wealth of potential tephra isochrons in Holocene deposits of the northeast Atlantic seaboard. It is clear also that calcareous lake sediments can be as fruitful a source of tephras as peats. Potential problems relating to dating and geochemical fingerprinting of tephra layers in individual sites are highlighted with reference to the Lairg tephras as recorded in Scotland and Northern Ireland, and to the Hoy tephra that has been described from Orkney.

Abstract: To investigate postglacial environmental changes in both the coastal and interior wet belts of British Columbia, fossil midges were analysed from two subalpine lakes, one adjacent to the lower Fraser canyon (Frozen Lake), and the other in Mount Revelstoke National Park (Eagle Lake). The midge stratigraphy for Frozen Lake revealed an abundance of rheophilous chironomid taxa and Simuliidae larvae, refecting the presence of an inflowing stream. An abundance of Chaoborus mandibles and Microtendipes during the early Holocene (c. 10100–7700 14C years BP, c. 11500–8500 cal. years BP) suggests warmer temperatures. A subsequent decline in the warm indicators and relative increases in cold stenotherms (Heterotrissocladius and Diamesa) indicate cooling until present day. This climate reconstruction is consistent with other quantitative and qualitative evidence for past climatic change in southern British Columbia. At Eagle Lake the warm indicators, Dicrotendipes and Polypedilum, are seen in the early Holocene (c. 85...

Abstract: The results are presented of a detailed plant macrofossil analysis of a C-14 dated Holocene organic sequence from a sub-Antarctic island, South Georgia. In the peat infilling of a rock basin 31 bryophyte species and many of the principal species of the present-day angiosperm flora, associated with bog communities, have been identified. The zonation of the bryophytes and the seeds and fruits shows a striking correspondence with the sediment stratigraphy, and indicates five ecological phases. The first four reflect a succession from a minerotrophic shallow pool to an ombrotrophic Warnstorfia-Polytrichum bog. After the deposition of a greyish-brown layer, c. 2200 C-14 years BP, a wet Deschampsia-Warnstofia-Sanionia-Rostkovia bog came into existence, which is still present today. The ecological phases are radiocarbon dated. They can be interpreted in terms of climate development during the Holocene. Climate ameliorated rapidly at about 10 000 C-14 years BP followed by a drier period. Around 7000 C-14 years BP the climate became wetter and the following c. 2500 years probably represent the climatic optimum. Between 4500 and 2600 C-14 years BP, drier conditions prevailed at the study site. The most striking change occurred at 2600 C-14 years BP when a marked change in vegetation and ecology indicates much wetter conditions. (Less)

Abstract: A high-resolution record of late-Holocene subsurface water-mass characteristics in outer Igaliku Fjord, South Greenland, is presented based on benthic foraminifera faunas from core PO 243–451 collected from a water depth of 304 m. Strati” cation with Atlantic water masses present in the lower part of the water-column is suggested to have prevailed during the last 3200 cal. years, except for a period referred to as the‘Mediaeval Warm Period’ (MWP). During the MWP (c. ad 885–1235) the outer part of Igaliku Fjord experienced enhanced vertical mixing and a high hydrodynamic energy level which we ascribe to increasing wind stress through this period, corresponding to the period of the Norse settlement. The transition from the MWP to the‘Little Ice Age’ (LIA) shows a two-step pattern with a short climatic amelioration around AD 1520 before maximum cooling occurred. The intensified wind stress and the overall environmental change are suggested to have contributed to the loss of the Norse settlement in Greenland. Periods with strong stratification and marked in uence of Atlantic subsurface water masses around 2.6, 1.3 ka BP and during the LIA are correlated to North Atlantic Holocene ice-rafting events reported by Bond et al. (1997).

Abstract: The uppermost limits of past treelines in the Alps are established using soil type and soil charcoal mass. In all the studied sites, a sharp decrease of soil charcoal mass is correlated with the upper altitudinal limit of podzols. On the basis of this evidence, the uppermost tree limit reached 2500 +/- 100 m a.s.l. in the Valaisan Alps during the Holocene, i.e., it was 250 +/- 100 in higher than today's potential treeline. Consequently, the timberline would have reached 2400 +/- 100 m a.s.l.. From the strong decline of charcoals concentration in soils above 2500m a.s.l., we infer that conifer species were rare or very rare above this altitude during the Holocene. Joint interpretation of charcoal, pollen, soil and macrofossil data suggest that alpine meadows with at most scattered conifers were present throughout the Holocene in the today's middle and upper alpine belt.

Abstract: The result of long-term environmental and human interaction is a variety of potential human responses to major natural crises: population aggregation or dispersal, changes in economic strategies an...

Abstract: The stable isotope records of four stalagmites dated by 19 TIMS uranium series ages are combined to produce master chronologies for delta(18)O and delta(13)C The delta(18)O records display good overall coherence, but considerable variation in detail. Variability in the delta(13)C records is greater, but general trends can still be discerned. This implies that too fine an interpretation of the structure of individual isotopic records can be unreliable. Speleothem delta(18)O values are demonstrated to show a positive relationship with temperature by comparing trends with other proxy records, but also to respond negatively to rainfall amount. Speleothem delta(13)C is considered to be most influenced by rainfall. The postglacial thermal optimum occur-red around 10.8 ka BP, which is similar in timing to Antarctica but up to 2000 years earlier than most Northern Hemisphere sites. Increasingly negative delta(18)O values after 7.5 ka BP indicate that temperatures declined to a late mid-Holocene minimum centred around 3 ka BP, but more positive values followed to mark a warm peak about 750 years ago which coincided with the 'Mediaeval Warm Period' of Europe. Low 5110 values at 325 years BP suggest cooling coincident with the 'Little Ice Age'. A marked feature of the delta(13)C record is an asymmetric periodicity averaging c. 2250 years and amplitude of c. 1.9parts per thousand. It is concluded that this is mainly driven by waterbalance variations with negative swings representing particularly wet intervals. The 5110 record shows a higher-frequency cyclicity with a period of c. 500 years and an amplitude of c. 0.25 parts per thousand. This is most likely to be temperature-driven, but some swings may have been amplified by precipitation.

Abstract: Laguna Mar Chiquita, a highly variable closed saline lake located in the Pampean plains of cetral Argentina, is presently the largest saline lake in South America ("-6000km2) The availability of hitorical, instrumental lake-level and salinity data for the past 100 years allows for the calibration of the isotopic archive recorded in the lake sediments Prolonged intervals with either negative or positive hydrlogical balances have severely modified lakewater levels, salinity and primary productivity, and have also controlled the isotopic composition of both the authigenic carbonate (&8Ooarb and f133Ccarb) and sedimetary organic matter (6"C0,,) Extensive evaporation during lowstand stages results in an enrichment of 180 and 13C in the lake waters, and is recorded in the sediments as the most positive &8O8arb and 613C carb compositions (00%o and-19Yoo, respectively) Conversely, more negative 6f'8Ocarb and 813Ccarb values (-18%o and-38Yoo, respectively) are the result of increasing freshwater input into

Abstract: Shores of eastern Hokkaido rose by perhaps I m a few centuries ago. The uplifted area extended at least 50km along the southern Kuril Trench. It included the estuaries Akkeshi-ko and Hichirippu, on...

Abstract: Colorimetric measurements of alkaline extracts from two Swiss peat cores have provided a complete 14500-year-long record of peat humification, a proxy of effective precipitation. Peat from the cold Younger Dryas (11050–9550 cal. bc) was well preserved despite low levels of precipitation. A particularly dry period, peaking at c. 7100 cal. bc, is indicated by well-decomposed peat. Peat from c. 6750–4250 cal. bc shows a low degree of decomposition, indicating a wet bog surface despite relatively warm temperatures and therefore indicating high levels of precipitation. A sharp transition to higher levels of decomposition c. 4450–3750 cal. bc indicates a major transition to a drier bog surface. Subsequently, peat humification generally decreases towards the end of the deeper profile (c. cal. ad 1050), indicating a gradual return to wetter conditions. This gradual decrease is punctuated by periods of particularly low humification which appear to be due to shifts to higher levels of effective precipitation from c. 2500 to 1350 cal. bc, c. 1050 to 550 cal. bc, centered around 150 cal. bc, and from c. cal. ad 550 onwards. Anthropogenic influences appear to have affected peat humification at the site at least since the Middle Ages. This study indicates that humification in colder regions/time periods could be more affected by temperature than precipitation and vice versa.

Abstract: Inland dunefields found in Breckland, East Anglia, UK, have previously been correlated with the widespread late-Devensian coversands of the region and a seventeenth-century 'sandflood' which is known to have inundated the village of Santon Downham. A programme of optically stimulated luminescence and radiocarbon dating undertaken on the dunes at Wangford Warren and Santon Downham reveals that episodic aeolian activity has taken place during the last 7000 years. Five sand depositional phases on Breckland dunes are identified: c.6500, c.1600 1100, c.500, c.400 335 and c.200 30 years before present. Between c.2120 and 1840 years ago and within the period 1100 300 years ago quiescent periods allowed the development of fen peat and soils. Local controlling factors on aeolian activity in Breckland appear to be related to anthropogenic activities and livestock (sheep and rabbits) reducing vegetation cover, and decreased precipitation and sea levels which led to lowering of water tables. Breckland aeolian activity, when compared to the national and subcontinental Holocene aeolian activity record, shows a high level of concordance. The underlying forcing factor for late-Holocene dune activity in the UK and elsewhere in Europe appears to be climatic instability in the North Atlantic, associated with both the 'Little Ice Age' and previous similar events which led to increased storminess, climatic variability and lower temperatures.

Abstract: Hunt, C. Elrishi, H. Gilbertson, D. Grattan, J. McLaren, S. Pyatt, B. Rushworth, G. Barker, G. Early-Holocene environments in the Wadi Faynan, Jordan. The Holocene. 2004. 14,6 pp 921-930

Abstract: Wiley to be a winner. While this is a useful addition to the environmental literature, it will have limited appeal for undergraduate courses such as geography or environmental science, especially as an isolated text. Readers of The Holocene may find this book interesting, although not momentous, and certainly not vital, because there is an absence of environmental history on scales greater than about 50 years.

Abstract: Middle-to late-Holocene palaeoclimate change has been reconstructed at high resolution by the analysis of the carbon and oxygen isotopes from a thermal ionization mass spectrometric (TIMS) U/Th dated stalagmite from Xiangshui Cave, near Guilin, Guangxi Province, China. The carbon and oxygen isotopic records from the stalagmite suggest that changes in the Asian monsoon since the middle Holocene (6000 BP) can be divided into two periods: (1) an interval from 6000 to 3800 BP when a strong East Asian summer monsoon gradually weakened and climate was relatively warm and humid; (2) a cool period from 3800 to 373 BP when the East Asian summer monsoon was relatively weak and the winter monsoon was probably relatively strong. This cooler interval was interspersed with a number of short warm periods. A This interpretation is largely based upon the general increase in 6180 values of the stalagmite between 6000 and 3800 BP and shifts in 6180 about a relatively heavy mean value between 3800 and 373 BP. The 6000 to 380...

Abstract: Information on East Antarctic coastal environments during the Holocene is relatively sparse. This is surprising as sedimentary records from the interface between land and sea can provide chronologies of climatic change, isostatic uplift, relative sea level and the colonization of newly formed biomes. Here we examine a sediment core from Pup Lagoon, a coastal lake in the Larsemann Hills, East Antarctica. Sediment stratigraphy, fossil pigments and diatoms were used to infer the sequence of Holocene environmental and climatic change. Results show that between 5800 and 5500 cal. yr BP the marine coast of Prydz Bay was characterized by stratified, open-water conditions during spring and summer and seasonally warm conditions. From 5500 to 2750 cal. yr BP sea-ice duration in Prydz Bay increased with the coast being ice-free for 2-3 months each year, conditions which are similar to the present day. A return to stratified, open-water conditions and a reduction in winter sea-ice extent between 2750 and 2200 cal. yr BP is signalled by enhanced biogenic production and more open-water diatom taxa. This is consistent with evidence for the mid-Holocene Hypsithermal detected in other records in East Antarctica. Isostatic isolation of the Pup Lagoon basin from the sea between 2200 and 2000 cal. yr BP slightly precedes the emergence of lakes with comparable sill heights from the nearby Vestfold Hills. The colonization of Pup Lagoon after its isolation as a freshwater lake was initiated by a siliceous flora dominated by stomatocysts with microbial mat development being prevented by mechanical or physical stress. A brief period of marine incursion following the mid-Holocene Hypsithermal may be related to local events such as iceberg calving or to minor sea-level change. Weighted averaging regression, used to infer salinity in the lacustrine zone, shows that from 1500 cal. yr BP Pup Lagoon is a freshwater lake, where the flora is dominated by stratified cyanobacterial mats, with green algae and diatoms as co-dominants, comparable to modem Pup Lagoon and other lakes in the Larsemann Hills.

Abstract: Lake sediments from Waskey Lake, Ahklun Mountains, southwestern Alaska were studied to decipher the history of upvalley glacier e uctuations during the Holocene. Several indicators of glacier activity were measured including: magnetic susceptibility, organic-matter content, grain-size distribution, bulk-sediment mineralogy and diatom assemblages. Seven radiocarbon ages on macrofossils, along with cross-checks by tephrochronology, provide the chronology of the cores. The results from core WL-1 indicate that glaciers lingered near Waskey Lake until 9100 cal. yr BP, perhaps under conditions of high winter accumulation. Peak organic-matter content occurs at 7400 cal. yr BP, when precipitation might have shifted to summer. The onset of Neoglaciation occurred 3100 cal. yr BP, and glaciers reached their maximum extent ~700 cal. yr BP. This chronology is consistent with the lichenometrically dated moraines from the glacier foree elds. Although the ages are tentative, the youngest and most widespread group of moraines was deposited sometime between 650 and 200 cal. yr BP (during the ' Little Ice Age' ). Since then, glaciers in the Waskey Lake area have shrunk by ~50% and equilibrium-line altitudes (ELA) have risen by 35 6 22 m. This rise in ELA is much less than the 100 to 200 m rise observed elsewhere in Alaska and indicates considerable spatial variability in late- Holocene climatic change.