Holocene deposits from Neptune's Cave, Nordland, Norway: Environmental interpretation and relation to the deglacial and emergence history of the Velfjord–Tosenfjord area

Neptune's Cave in the Velfjord–Tosenfjord area of Nordland, Norway is described, together with its various organic deposits. Samples of attached barnacles, loose marine molluscs, animal bones and organic sediments were dated, with radiocarbon ages of 9840 ± 90 and 9570 ± 80 yr BP being derived for the barnacles and molluscs, based on the superseded but locally used marine reservoir age of 440 years. A growth temperature of c . 7.5 °C in undiluted seawater is deduced from the δ¹³C and δ¹⁸O values of both types of marine shell, which is consistent with their early Holocene age. From the dates, and an assessment of local Holocene uplift and Weichselian deglaciation, a scenario is constructed that could explain the situation and condition of the various deposits. The analysis uses assumed local isobases and sea-level curve to give results: that are consistent with previous data, that equate the demise of the barnacles to the collapse of a tidewater glacier in Tosenfjord, and that constrain the minimum extent of local Holocene uplift. An elk fell into the cave in the mid-Holocene at 5100 ± 70 yr BP, after which a much later single 'bog-burst' event at 1780 ± 70 yr BP could explain the transport of the various loose deposits further into the cave.     

Lateglacial and Holocene terrestrial and marine proxies reflecting climate changes in the Malangen fjord area, Norway, northeast North Atlantic

A high-resolution Younger Dryas–late Holocene record of climate and environment from the Malangen fjord has been established on the basis of two marine sediment cores. Five pollen-spore assemblage zones have been defined covering the period c . 11 500 cal. yr BP (10 200 ¹⁴C yr BP) to c . 1600 cal. yr BP (1600 ¹⁴C yr BP) with a hiatus of c . 2000 cal. years between c . 10 200 and 8100 cal. yr BP (9000 and 7300 ¹⁴C yr BP). The Holocene vegetation development from pioneer vegetation to forest development, identified in the marine pollen record, correlates well with pollen records from terrestrial sections of northern Norway. The marine pollen record was also correlated directly with marine proxy records of the bottom water temperature investigated in the same sediment cores. Correlation between the marine and terrestrial proxies suggests that changes in the influx of warm Atlantic Water to the fjord led to an instant change in the vegetation of the surrounding land area. The results thus support a strong link between marine and atmospheric mean climatic states in the North Atlantic region throughout the Holocene.     

Extinction chronology and palaeobiology of the cave bear (Ursus spelaeus)

The cave bear ( Ursus spelaeus ) was one of several spectacular megafaunal species that became extinct in northern Eurasia during the late Quaternary. Vast numbers of their remains have been recovered from many cave sites, almost certainly representing animals that died during winter hibernation. On the evidence of skull anatomy and low δ¹⁵N values of bone collagen, cave bears appear to have been predominantly vegetarian. The diet probably included substantial high quality herbaceous vegetation. In order to address the reasons for the extinction of the cave bear, we have constructed a chronology using only radiocarbon dates produced directly on cave bear material. The date list is largely drawn from the literature, and as far as possible the dates have been audited (screened) for reliability. We also present new dates from our own research, including results from the Urals. U. spelaeus probably disappeared from the Alps and adjacent areas – currently the only region for which there is fairly good evidence – c . 24 000 radiocarbon years BP ( c . 27 800 cal. yr BP), approximately coincident with the start of Greenland Stadial 3 ( c . 27 500 cal. yr BP). Climatic cooling and inferred decreased vegetational productivity were probably responsible for its disappearance from this region. We are investigating the possibility that cave bear survived significantly later elsewhere, for example in southern or eastern Europe.     

Chronology and organic chemistry of the Black Creek Swamp Megafauna site (Late Pleistocene), Kangaroo Island, Australia

The timing of the extinction of the Australian Megafauna and whether it was simultaneous and widespread has been a much researched topic in Quaternary geoscience. The Black Creek Swamp Megafauna site on Kangaroo Island was thought to be a refugium for Megafauna; however, recent and multidiscipline age determinations have established that the fossils are considerably older than the well-quoted extinction age of 45 kyr. Further radiocarbon age determinations, δ¹³C isotope analysis and ¹³C-NMR spectroscopy of the fossil containing organic matter demonstrates that it is highly soluble and accumulated as recently as 31–18 cal. kyr BP. These radiocarbon ages are much younger than the 100–50 kyr age bracket ascertained for the fossil material itself, implying separate episodes of death, deposition and burial. The soluble nature of the organic matter and increasing radiocarbon ages with depth suggests lateral accumulation, probably transported by subsurface waters from elevated areas proximal to the low-lying swamp. Such depositional conditions and ¹⁴C age range implies that the site may have experienced an unusually wet Last Glacial Maximum, due maybe to its proximity to the continental shelf and thus to maritime conditions. C3 vegetation dominates the Black Creek Swamp and its organic matter (δ¹³C; −30‰ and −23‰); however, variations in δ¹³C may indicate climatic shifts. ¹³C-enrichment and an abundance of salt-tolerant gastropods within the site's final phase of sediment accumulation (<6 cal. kyr BP) suggest that conditions during this most recent period were not as wet as those of the Last Glacial Maximum.     

The Fossvogur marine sediments in SW Iceland - confined to the Allerød/Younger Dryas transition by AMS 14 C dating

An exhaustive ¹⁴C dating programme of molluscs from the Fossvogur sediments in Reykjavik. Iceland is presented. For the first time all the fossiliferous units of the sediments are dated. The results confirm earlier conclusions of a widespread occurrence of marine sediments of Allerød age in Reykjavik. The set of dates from the Fossvogur sediments shows a narrow ¹⁴C age distribution (standard deviation of ±235 years) of molluscs from all localities and from successive marine units in vertical sections. The weighted mean conventional ¹⁴C age is 11,400 BP. Assuming a reservoir effect of 400 years. this corresponds to a reservoir-corrected age of I1,000 BP. i.e. the Allerød- Younger Dryas transition for the sampled units, These new ¹⁴C dates from Fossvogur confirm the need for a revision of the Upper Pleistocene chronology of the Reykjavik region. They also have a bearing on the Late Weichselian record of glacier readvances and sea-level changes in the area. The dates suggest that the marine units in Fossvogur accumulated within a restricted time-span of a few hundred years. The sediments in Fossvogur are of volcaniclastic origin and are extremely lithified, indicating local geothermal activity soon after their deposition. This may explain anomalously high D/L amino acid ratios measured in molluscs from the Fossvogur sediments. δ¹³C and δ¹⁸O results suggest that temperatures may have ranged up to 60°C.     

A distinct δ13C decline in organic lake sediments at the Pleistocene-Holocene transition in southern Sweden

Values of δ¹³C obtained from conventional bulk sediment radiocarbon dates encompassing the Pleistocene Holocene boundary have been compiled and plotted against ¹⁴C age. In all. 286 lake sediment dates from southern Sweden in the range 8.000 to 13.000 BP have been evaluated. A significant decrease in δ¹³C values, initiated shortly before 10.000 RP and amounting to 5%, is distinguished. This change is accompanied by increased limnic productivity. decreased erosive input and increased organic carbon content of the sediments. A probable explanation for the δ¹³C decline in organic material is decreased importance of dissolution of silicates at the transition to the Holocene. During the Late Weichselian. extensive weathering of exposed minerogenic material with subsequent input of bicarbonate to the lake water may have caused a relative enrichment of ¹³C in dissolved inorganic carbon. Furthermore, the early Holocene increase in terrestrial vegetation cover probably led to an increased supply of ¹³C depleted carbon dioxide to the lake water by root respiration. Altered limnic vegetation, presumably towards increased production of phytoplankton. could also have contributed to the observed decreasing δ¹³C trend. The importance of these processes compared to other possible influencing factors. mainly endogenic carbonate production and changes in the global carbon cycle. is discussed.     

Dating of the near-surface layer of a peatland in northwestern Ontario, Canada

The near-surface layer of the dominant microhabitat types on a peatland in the Rainy River area, northwestern Ontario, Canada was dated using a number of previously published methods. No single method was found to be appropriate in all microhabitat types, and discrepancies of up to 15 yr over a time-scale of 80 yr were encountered. The results suggested that the post-depositional mobility of ²¹⁰Pb, and possibly its atmospheric supply, are affected by microhabitat type. ²¹⁰Pb dates consistently underestimated independently derived dates in the uppermost sections of the cores. Ages derived by measuring the length of annual increments on moss stems were in general agreement with the ²¹⁰Pb dates, but were subject to bias where the moss remains were poorly preserved. ¹⁴C analyses on material from the base to the near-surface horizon confirmed the modern (post-AD 1950) origin suggested by the ²¹⁰Pb and moss increment dates. Increased ash content at the base of the near-surface layer was correlated with the dustbowl of the 1930s, but assignment of dates to other stratigraphic markers (charcoal, Ambrosia pollen, and Larix needles) was less certain. The ash peak (55 yr before AD 1990) was used as datum for relative dating methods based on assumptions of a constant rate of peat accumulation (constant bulk density method) and constant rate of pollen accumulation (pollen density method). The constant bulk density method provided quick, inexpensive estimates of maximum age, but could not be extrapolated beyond datum, nor applied to cores showing marked stratigraphic changes. The pollen density method was a valuable but time-consuming alternative for dating peatland depressions, which lack annual moss increments and are subject to ²¹⁰Pb leaching.     

New stratigraphic markers in the late Pleistocene Palouse loess: novel fossil gastropods, absolute age constraints and non-aeolian facies

Four stratigraphic sections in the southern part of the Columbia Basin preserve a sequence of aeolian and non-aeolian sediments ranging in age from 9·43 to >47·0 ¹⁴C ka based on accelerator mass spectrometry radiocarbon dating of fossil molluscs, geochemistry of Cascade Mountain-sourced tephra and association with formally recognized pedostratigraphic units (the Washtucna and Old Maid Coulee soils). Study sections are interpreted as representing concurrent deposition of loess and distal Missoula Flood rhythmites in valleys tributary to main drainages backflooded during the Missoula Floods, and formation of carbonate and iron-rich soils. Sediments belong to the formally recognized L-1 and L-2 loess units established for the Palouse loess, which were deposited in the Columbia Basin subsequent to events of glacial outburst flooding. Sediments associated with the Mount Saint Helens set S and set C tephras in the study sections preserve a fauna of five species of gastropod mollusc which have not been reported previously from sediments of late Pleistocene age in the Palouse region. The fossils comprise two distinct faunules stratigraphically separated by the Mount Saint Helens So tephra. Accelerator mass spectrometry radiocarbon dating of the fossils collected above the tephra in two of the sections yielded ages of 12·48 ± 0·06 and 9·43 ± 0·05 ¹⁴C kyr. These ages suggest that independent determinations of the 13·35 ¹⁴C kyr age of the So tephra in other areas where Missoula Flood sediments are preserved are probably accurate, and help to refine the age of the latest events in the most recent sequence of catastrophic glacial outburst flooding.     

AMS 14C measurements and macrofossil analyses of a varved sequence near Pudozh, eastern Karelia, NW Russia

The laminated sediments at Pudozh in eastern Karelia are generally assumed to have been deposited between 13 000 and 16 000 ¹⁴C yr BP and have been used to date the recession of the active ice margin. However, 17 AMS ¹⁴C measurements performed on terrestrial plant macrofossils contained in these sediments show that deposition began during the late Allerφd, when the ice margin had already receded to the northern part of Lake Onega. Based on an age model, we assume that the 1933-year-long varved sequence covers the time period between c. 12 900 and 11 000 calendar years BP. During this period, which comprises the later part of the Late Weichselian and the early Holocene, the local vegetation consisted of open, tree-less dwarf shrub heaths. Increased soil erosion may have occurred before 12 550 calendar years BP.     

Deglaciation history of the southwestern Fennoscandian Ice Sheet between 15 and 13 14C ka BP

Analysis of 2D and 3D seismic records from the continental shelf off western Norway, in combination with chronological constraints from ¹⁴C dates, has led to a model for the glacial development in these shelf areas between c. 15 and 13 ¹⁴C ka BP. On the shallow Måløy Plateau adjacent to the Norwegian Channel, iceberg scours are preserved below a prominent moraine ridge, which by correlation to the Norwegian Channel indicate ice retreat at c. 15 ¹⁴C ka BP. Subsequently, the ice advanced across the scoured surface and deposited a till sheet before stabilizing to deposit a prominent moraine, termed the Bremanger Moraine. Based on location on the shelf, seismic stratigraphy, morphology and C dates the Bremanger Moraine is correlated with a significant moraine on the continental shelf off Trøndelag. We suggest that these features are products of a regional glacial event, the Bremanger Event, dated to <15–13.3 ¹⁴C ka BP. The Bremanger Event is probably a result of the deteriorating climatic conditions in the NE Atlantic during Heinrich event 1.     

10Be chronology of the last deglaciation of County Donegal, northwestern Ireland

A well-preserved moraine on the northern coast of County Donegal, Ireland, has played a critical role in our understanding of the glacial history of this sector of the Irish Ice Sheet (IIS). Because of a lack of numerical dating of the moraine, however, previous interpretations of its age and significance to the glacial history of this region have varied widely. Here we report eight in situ cosmogenic ¹⁰Be ages on boulders sampled from the moraine. Two of these ages are outliers, with the remaining six ranging from 18.8±1.0 ¹⁰Be kyr to 20.9±1.3 ¹⁰Be kyr, with an uncertainty-weighted mean age of 19.4±0.3 ¹⁰Be kyr (19.4±1.2 kyr accounting for production rate uncertainty). Our results confirm one previous ¹⁰Be age obtained from the moraine, with the combined data ( n =7) constraining the age of initial deglaciation of the IIS from its LGM position on the continental shelf to be 19.3±0.3 ¹⁰Be kyr (19.3±1.2 kyr accounting for production rate uncertainty). These ages are in excellent agreement with calibrated ¹⁴C ages that constrain retreat of the IIS margin from the continental shelf elsewhere in northwestern and western Ireland and the Irish Sea Basin associated with the start of the Cooley Point Interstadial (≥20–≤18.2 cal. kyr BP), suggesting widespread deglaciation of the IIS ∼19.5–20 kyr ago.     

Storegga tsunami sand in peat below the Tapes beach ridge at Harøy, western Norway, and its possible relation to an early Stone Age settlement

One of the early problems with the Storegga tsunami deposit was how to distinguish it from deposits of the midHolocene (Tapes) transgression. An excavation on Harøy, an island on the outermost western coast of Norway, shows a distinct, clean sand bed embedded in peat and clearly separated from the overlying Tapes beach deposits. This sand bed continues in the peat landwards of the beach ridge for at least 60 m. Radiocarbon dates of the peat show that the sand was deposited some time between 6900 and 7700 yr BP. The sedimentary structures of the bed, the ¹⁴C dates, and the fact that this is the only sand bed in the peat, suggest that the sand bed was deposited by a short-lived event, the Storegga tsunami. On the neighbouring island, Fjørtoft, a Stone Age settlement, dated to 7500 yr BP, was discovered in the early 1970s. The settlement was found underneath a sand bed that later had been covered by the Tapes beach ridge deposits. When discovered, the sand covering the settlement was inferred as eolian sand. However, this investigation shows that the Storegga tsunami deposited a widespread sand bed on the land surface around this time with a similar grain size distribution to eolian sand. It is therefore suggested that the sand bed covering this settlement was deposited from the Storegga tsunami. Both the stratigraphy and ¹⁴C dates demonstrate that the Tapes transgression maximum was reached well after the Storegga tsunami on Harøy, between 6500 and 6100 yr BP.     

Late-Glacial radiocarbon- and palynostratigraphy on the Swiss Plateau

A detailed late-glacial radiocarbon stratigraphy for the Swiss Plateau has been established on the basis of over 90 accelerator ¹⁴C dates on terrestrial plant macrofossils. Two plateaux of constant.,¹⁴C age were observed, occurring at 12,700 B.P. and at 10,000 B.P. The consequences of these plateaux for palaeo-ecological investigations are threefold: (1) a more refined ¹⁴C dating within the plateaux is not possible, (2) in teleconnections between different sites (if based on ¹⁴C dating and concerning the periods around 12,700 B.P. and 10,000 B.P.) events are considered synchronous which are only synchronous within a plateau of constant age, and (3) exact time-depth relationship and therefore influx calculations are made impossible during these plateau periods. A comparison of the radiocarbon ages derived from terrestrial, telmatic and limnic material at different sites on the Swiss Plateau yields a proposal for modifying the zonation system of Welten for the Late-Glacial. By retaining the limits of chronozones (at 13, 12, 11 and 10ka B.P.) and by refining the palynostratigraphic criteria for the limits of biozones, a separation between chrono- and biozonation at the beginning of the Belling and at the beginning of the Younger Dryas becomes obvious.     

Thermoluminescence dating of Dimlington Stadial deposits in eastern England

The loess component of a solifluction deposit of the Dimlington Stadial exposed at the inland site of Eppleworth in eastern England gave a thermoluminescence date of 17.5 ± 1.6 × 10³ years. The solifluction deposit is overlain by a slightly weathered till correlated with the Skipsea Till of coastal exposures. which lies between organic horizons with radiocarbon dates of 18,500–18,240 B.P. and 13,045 B.P. Although the till must have been deposited during the Dimlington Stadial (after 18,240 B.P. at Dimlington and after 17,500 B.P. at Epplcworth), it gave apparent TL dates of 42.1 ± 3.6 × 10³ years at Eppleworth and 102 ± 9 × 10³ years at Dimlington, indicating that the components of the till were not exposed to light immediately before deposition.     

Patterns of faunal extinction and paleoclimatic change from mid-Holocene mammoth and polar bear remains, Pribilof Islands, Alaska

Qagnaxˆ Cave, a lava tube cave on St. Paul Island in the Pribilofs, has recently produced a mid-Holocene vertebrate faunal assemblage including woolly mammoth, polar bear, caribou, and Arctic fox. Several dates on the mammoth remains converge on 5700 ¹⁴C yr BP. These dates, ~ 2300 yr younger than mammoth dates previously published from the Pribilof Islands, make these the youngest remains of proboscideans, and of non-extinct Quaternary megafauna, recovered from North America. Persistence of mammoths on the Pribilofs is most parsimoniously explained by the isolation of the Pribilofs and the lack of human presence in pre-Russian contact times, but an additional factor may have been the local existence of high-quality forage in the form of grasses enriched by nutrients derived from local Holocene tephras. This interpretation is reinforced by stable carbon and nitrogen isotope values obtained from the mammoth remains. The endpoint of mammoth survival in the Pribilofs is unknown, but maybe coterminous with the arrival of polar bears whose remains in the cave date to the Neoglacial cold period of ~ 4500 to 3500 ¹⁴C yr BP. The polar bear record corroborates a widespread cooling of the Bering Sea region at that time.     

The Holocene vegetation history of the Arfon Platform, North Wales, UK

Detailed pollen, charcoal and loss on ignition profiles were analysed from Llyn Cororion, North Wales, UK. The chronology was based on 11 radiocarbon dates. This site is particularly important for this region because its high-resolution record improves the spatial and temporal resolution of records of Holocene vegetation change in an area characterized by a highly variable environment. An early Holocene phase of Juniperus-Betula scrub was succeeded by Betula-Corylus woodland. Quercus and Ulmus were established by c. 8600 ¹⁴C yr BP, with Pinus dominating at c. 8430 ¹⁴C yr BP. Local disturbance then allowed the spread of Alnus; Tilia was a common component of the forest by 5650 ¹⁴C yr BP. Charcoal and pollen records suggest that by c. 2600 ¹⁴C yr BP there was progressive deforestation, increased use of fire and spread of grassland; the first cereal grain was recorded at c. 2900 ¹⁴C yr BP. Compared with data from upland Snowdonia, the results show that within a topographically diverse region there were significant local variations in forest composition. These variations developed as a response to interactions between many environmental parameters and were further complicated by the influence of human activity. In an area such as North Wales it is therefore unlikely that one site can be representative of regional Holocene vegetational development. The site is additionally important because it contributes to the data available for meta-analyses of environmental change in the North Atlantic region, particularly as detailed pollen diagrams from coastal lake sites around western Europe are rare.     

Chronology and paleoenvironments during the late Weichselian deglaciation of the southwest Iceland shelf

Foraminifera, sedimentology, and tephra geochemistry in core 93030-006 LCF from the southwestern Iceland shelf were used to reconstruct paleoenvironments between 12.7 and 9.4 ¹⁴C ka BP. Seismic-reflection profiles place the core in glacial-marine and marine sediments within one meter of the underlying glacial till. Foraminifers in the earliest glacial-marine sediments provide a record of ice-distal conditions and immigration of slope species onto the shelf in association with warm Atlantic water. Meltwater increased during the Allerød under a weakened Atlantic water influence. Arctic conditions began by 11.14 ₁₄C ka BP with an abrupt increase in meltwater and near exclusion of boreal fauna from the shelf. Meltwater diminished in the early Younger Dryas, coinciding with sea-surface cooling between 11.14 and 10.5 ¹⁴C ka BP. A slight warming recorded in the uppermost glacial-marine sediments was interrupted by an inferred jökulhlaup event emanating from glacier ice on the Western Volcanic Zone. Retreat of the ice margin from the sea sometime between c. 10.3 and 9.94 ¹⁴C ka BP coincided with this event. The onset of postglacial marine sedimentation occurred along with increasing evidence of Atlantic water c. 9.94 ¹⁴C ka BP and was interrupted by a short-lived Pre-boreal cooling of the Irminger Current c. 9.91 ¹⁴C ka BP. Conditions similar to those today were established by 9.7 ¹⁴C ka BP.     

Deglaciation and palaeoclimate of the Andfjord-Vågsfjord area, North Norway

This paper reviews the deglaciation history and palaeoclimate from 22 to 9.5 ¹⁴Cka BP in the Andfjord-Vagsfjord area. Eight main glacial events are recorded: The Egga-I (>22 ¹⁴Cka BP), the Bjerka, the Egga-II (>14.6 ¹⁴Cka BP), the Flesen (14.5 ¹⁴Cka BP), the D (13.8–13.2 ¹⁴Cka BP), the Skarpnes (12.2 ¹⁴Cka BP), the Tromsø–Lyngen (10.7–10.3 ¹⁴C ka BP) and the Stordal (10.0–9.5 ¹⁴Cka BP). Onset of the final deglaciation occurred about 14.6 ¹⁴Cka BP. Most of the western part of the Fennoscandian and Barents Sea Ice Sheets receded from the outer continental shelf 15–14 ¹⁴Cka BP. The delivery and melting of icebergs at this time to the Norwegian-Greenland Sea resulted in a low oxygen isotope event recorded in a number of cores in the region. Atlantic water intruded the area 13.2 ¹⁴Cka BP, and an atmospheric warming commenced 12.9/12.8 ¹⁴Cka BP. A marked glacial recession occurred before the Skarpnes event. During Allerød time, the glaciers retreated to the fjord heads or even farther inland. The Fennoscandian outlet glaciers readvanced (locally more than 40 km), reached their Younger Dryas outer limit after 10.7 ¹⁴Cka BP and retreated from this position before about 10.3 ¹⁴Cka BP.     

Lake Boksehandsken's earliest postglacial sediments and their palaeoenvironmental implications, Jameson Land, East Greenland

Lake Boksehandsken, the largest lake on Jameson Land, central East Greenland, is situated 54 m a.s.l. and holds a long (6.3 m) and complex stratigraphy. It was analysed with respect to lithology, carbon content, ¹⁴C, micro- and macrofossils. The diamict material in the bottom is overlain by a fining-upwards sequence, possibly deposited close to a receding ice margin in a glaciomarine environment. These deposits are interpreted to have been formed at the time of the marine limit ( c . 70 m) in the area. In spite of a large series of ¹⁴C datings, very few of the obtained dates were considered reliable. This is because the sediments contain coal fragments and old redeposited plant remains. Based on a set of arguments and correlations to the surrounding glacial stratigraphy it is implied that the marine limit and deglaciation cannot be much older than 10,000 BP. The lithology of the lake sediments, in combination with occurrence of marine macrofossils. shows that deglaciation was succeeded by a (glacio)marine depositional environment. The lake was isolated from the sea at c . 9000 BP. followed by a short transgression and a final isolation at c . 8400 BP. This sequence of events is demonstrated by both litho-and biostratigraphy and possible causes are discussed. A later oscillation some time between 8000 and 7500 BP. evidenced by litho-, carbon-, pollen- and Pecliastrum stratigraphy, is interpreted as a regional climatic cooling possibly correlatable to a distinct δ¹⁸O minima in the Greenland ice cores.     

Associated terrestrial and marine fossils in the late-glacial Presumpscot Formation, southern Maine, USA, and the marine reservoir effect on radiocarbon ages

Excavations in the late-glacial Presumpscot Formation at Portland, Maine, uncovered tree remains and other terrestrial organics associated with marine invertebrate shells in a landslide deposit. Buds of Populus balsamifera (balsam poplar) occurred with twigs of Picea glauca (white spruce) in the Presumpscot clay. Tree rings in Picea logs indicate that the trees all died during winter dormancy in the same year. Ring widths show patterns of variation indicating responses to environmental changes. Fossil mosses and insects represent a variety of species and wet to dry microsites. The late-glacial environment at the site was similar to that of today's Maine coast. Radiocarbon ages of 14 tree samples are 11,907 ± 31 to 11,650 ± 50 ¹⁴C yr BP. Wiggle matching of dated tree-ring segments to radiocarbon calibration data sets dates the landslide occurrence at ca. 13,520 + 95/−20 cal yr BP. Ages of shells juxtaposed with the logs are 12,850 ± 65 ¹⁴C yr BP (Mytilus edulis) and 12,800 ± 55 ¹⁴C yr BP (Balanus sp.), indicating a marine reservoir age of about 1000 yr. Using this value to correct previously published radiocarbon ages reduces the discrepancy between the Maine deglaciation chronology and the varve-based chronology elsewhere in New England.