Stable isotope record of sediment cores from the North Atlantic

Abrupt and short climate changes, such as the Younger Dryas, punctuated the last glacial-to-interglacial transition (Ruddiman and McIntyre, 1981 doi:10.1016/0031-0182(81)90097-3; Duplessy et al., 1981 doi:10.1016/0031-0182(81)90096-1; Oeschger et al. 1984; Broecker et al., 1985 doi:10.1038/315021a0). Broecker et al. (1988 doi:10.1029/PA003i001p00001) proposed that these may have been caused by an interruption of thermohaline circulation as inputs of glacial meltwater freshened the surface waters of the North Atlantic. The finding (Fairbanks, 1989 doi:10.1038/342637a0) that meltwater discharge was minimal during the Younger Dryas, however, led to the suggestion that the surface-water salinity drop might have been caused instead by changes in the freshwater budget (the difference between precipitation and evaporation), accompanied by a reduction in poleward advection of saline subtropical water. Here we use micropalaeontological and stable-isotope records from foraminifera in two cores from the North Atlantic to generate two continuous, high-resolution records of sea surface temperature and salinity changes over the past 18,000 years. Despite the injection of glacial meltwater during warm episodes, we find that sea surface salinity and temperature remain positively correlated during deglaciation. Cold, low-salinity events occurred during the early stages of deglaciation (14,500-13,000 years ago) and the Younger Dryas, but the minor injections of meltwater at high latitudes during these events are insufficient to account for the observed salinity changes. We conclude that an additional feedback from changes in the hydrological cycle and in advection was necessary to trigger changes in thermohaline circulation and thus in climate. This feedback did not act when the meltwater injection occurred at low latitude.

Seawater Cd reconstruction for the western subtropical South Atlantic

Benthic foraminiferal Cd/Ca from an intermediate depth, western South Atlantic core documents the history of southward penetration of North Atlantic Intermediate Water (NAIW). Cd seawater estimates (CdW) for the last glacial are consistent with the production of NAIW and its export into the South Atlantic. At ~14.5 ka concurrently with the onset of the Bølling-Allerød to Younger Dryas cooling, the NAIW contribution to the South Atlantic began to decrease, marking the transition from a glacial circulation pattern to a Younger Dryas circulation. High CdW in both the deep North Atlantic and the intermediate South Atlantic imply reduced export of deep and intermediate water during the Younger Dryas and a significant decrease in northward oceanic heat transport. A modern circulation was achieved at ~9 ka, concurrently with the establishment of Holocene warmth in the North Atlantic region, further supporting a close linkage between deepwater variability and North Atlantic climate.

Heavy and light minerals in turbidites from DSDP Hole 19-183, the Aleutian abyssal plain

The Aleutian abyssal plain is a fossil abyssal plain of Paleogene age in the western Gulf of Alaska. The plain is a large, southward-thinning turbidite apron now cut off from sediment sources by the Aleutian Trench. Turbidite sedimentation ceased about 30 m.y. ago, and the apron is now buried under a thick blanket of pelagic deposits. Turbidites of the plain were recovered at site 183 of the Deep Sea Drilling Project on the northern edge of the apron. The heavy-mineral fraction of sand-sized samples is mostly amphibole and epidote with minor pyroxene, garnet, and sphene. The light-mineral fraction is mostly quartzose debris and feldspars. Subordinate lithic fragments consist of roughly equal amounts of metamorphic, plutonic, sedimentary, and volcanic grains. The sand compositions are arkoses in many sandstone classifications, although if fine silt is included with clay as matrix, the sand deposits are feldspathic or lithofeldspathic graywacke. The sands are apparently first-cycle products of deep dissection into a plutonic terrane, and they contrast sharply with arc-derived volcanic sandstones of similar age common on the adjacent North American continental margin. The turbidite sands are stratigraphically remarkably constant in composition, which indicates derivation from virtually the same terrane through a time span approaching 20 m.y. Comparison of Aleutian plain data with the compositions of coeval sedimentary rocks from the northeast Pacific margin shows that the Kodiak shelf area includes possible proximal equivalents of the more distal turbidites. Derivation from the volcaniclastic Mesozoic flysch of the Shumagin-Kodiak shelf is unlikely; more probably the sediments were derived from primary plutonic sources. The turbidites also resemble deposits in the Chugach Mountains and the younger turbidites of the Alaskan abyssal plain and could conceivably have been derived from the coast ranges of southeastern Alaska or western British Columbia. The Aleutian plain sediment most likely was not derived from as far south as the Oregon-Washington continental margin, where coeval sedimentary deposits are dominantly volcaniclastic.

Stable isotope record of planktonic foraminifera from the Sulu Sea

A high-resolution, accelerator mass spectroscopy 14C dated sediment record from the Sulu Sea clearly indicates that the Younger Dryas event affected the western equatorial Pacific. Planktonic foraminiferal delta18O and abundance data both record significant changes during Younger Dryas time. In particular, a 0.4 per mil increase in the delta18O value of Globigerinoides ruber and the reappearance of the cool water planktonic foraminifera, Neogloboquadrina pachyderma, occur during the Younger Dryas at this location. These isotopic and faunal changes are a response to either surface water temperature or salinity changes, or some combination of the two. Changes in surface salinities could have been accomplished through either local or global processes. Intensification of the monsoon climate system and increased precipitation at approximately 11 ka is one mechanism that may have resulted in local changes in salinity. A meltwater pulse derived from the Tibetan Plateau is another mechanism which may have caused local changes in salinity. The presence of the Younger Dryas in the tropical western Pacific clearly indicates that this climatic event is not restricted to the North Atlantic or high latitudes, but rather is global in extent.

Relative abundances of foraminifera and radiocarbon ages of selected cores obtained from the Nordic and Barents Sea

Ocean circulation changes along the continental shelf of the Nordic and Barents Seas have been investigated in order to reconstruct regional changes in the inflow of Atlantic Water (AW) through the last 16,000 calibrated (cal) years (yr) B.P. We have selected five time-slices representing the late glacial (16,000-15,000 cal yr B.P.), the Bølling-Allerød warm interstadials (14,500-13,500 cal yr B.P.), the Younger Dryas cold stadial (12,500-11,500 cal yr B.P.), the early Holocene (9500-7500 cal yr B.P.) and the late Holocene (4000-2000 cal yr B.P.). Twelve previously published records of the distribution of benthic foraminifera faunas and ice-rafted debris have been compiled. The earliest sign of Atlantic Water inflow was recorded at the northern Iceland shelf at 16,000-15,000 cal yr B.P. The inflow of warm AW to the Nordic Seas shelf has been persistent since, but with variable strength and geographic pattern. An apparent zonal seesaw pattern in the strength of the Norwegian Atlantic Current (NwAC) and the Irminger Current (IC) during the late glacial, Bølling-Allerød and Younger Dryas periods was found. During the Holocene, no zonal differences in the inflows of NwAC and IC were found. A strong meridional gradient with warmer conditions at lower latitudes and relatively cold conditions at high northern latitudes existed.

Pollen profiles from three former lakes in the Lake Garda area

1. Late glacial and postglacial sediments from three former lakes in the Lake Garda area (Southern Alps) were investigated. 2. The pollen diagram from Bondone (1550 m) shows an older phase rich in NAP. A younger one corresponds with the Younger Dryas time according to two radiocarbon determinations. In the Preboreal no climatic deterioration could be found. 3. At first plants, which are nowadays typical for snow-ground, pioneer and dwarf shrub associations, immigrated into the surroundings of Bondone. In Alleröd times larch and pine appeared as the first trees. At the beginning of the Preboreal dense forest existed in that region. During the Alleröd timber line was at about 1500 m. 4. In the pollen diagrams from Saltarino (194 m) and Fiavè (654 m) an oldest period rich in NAP is followed by two stadial and two interstadial phases. Tree birches and larches immigrated during the oldest interstadial phase. 5. In the case of Saltarino and Fiavè only a preliminary dating could be made. A correlation seems to be possible with diagrams published by Zoller as well as with the diagram of Bondone. Discrepances in dating, which arise then, are discussed. According to the two possibilities of dating the youngest stadial is synchronous either with the so-called Piottino stadial or the Younger Dryas time. Consequently the oldest interstadial phase of Saltarino corresponds either with the Bölling or with a pre-Bölling interstadial. The last possibility seems to be more probable. 6. In the southern part of the Lake Garda area reforestation was preceded by a long shrub phase mainly with Juniperus. At about 650 m there was a period with Pinus mugo and only with a small amount of Juniperus before reforestation. A phase with Betula nana well known from areas north of the Alps could nowhere be found. 7. In the area under study larch appeared as the first tree. Lateron it has been the most important constituent of the forests near timber line. Birch, which plays an important role as a pioneer tree in Denmark - for instance at the transition of the pollen zones III/IV - as well as in Southern Germany during Bölling time, was of less importance at the southern border of the Alps. In that area the spreading of Pinus occurred very early causing dense forests. 8. During the last stadial phase (probably Younger Dryas time) dense forests with Pinus and Larix existed at 650 m. In the lower part of the Lake Garda area, however, both thermophilous trees as Quercus and herbs frequently occurred. This leads to the conclusion that during this time tree growth was limited by dryness in lower altitudes of the border of the Southern Alps. Pinus and Juniperus, however, do not show higher values in this period, a fact which cannot yet be explained. 9. A list of plants, which were found in the sediments, is compiled. Helodium lanatum, Dictamnus albus, Mercurialis cf. ovata, Buxus, Cerinthe cf. minor, Onosma, Anthericum and Asphodelus albus are findings, which are of special interest for the history of the flora of that region.

Sedimentology and Cd/Ca ratios of benthic foraminifera from ODP Site 172-1060 in the western Nort Atlantic

The Western Boundary Undercurrent (WBUC), off eastern America, is an important component of the Atlantic Meridional Overturning circulation and is the principal route for southward transport of North Atlantic waters and southward return of Southern Source Water (SSW). Here a direct flow speed proxy (mean grain size of the sortable silt) is used to infer the vigour of flow of the palaeo-WBUC at Blake Outer Ridge, (ODP Site 1060, depth 3481 m) during Marine Isotope Stage (MIS) 3. The overall shape of the flow speed proxy record shows a complex pattern of variability, with generally more vigorous flow and larger-scale flow variations between 35 and 60 ka than in the younger part of MIS 3 and MIS 2 (b35 ka). Six events of reduced bottom flow vigour (Slow Events, SEs) occur. These appear uncorrelated with Heinrich events, but are instead synchronous with the warming phases of Antarctic Warm Events A-1 to A-4 (with one new one, A-1a and one poorly defined, 'A-0'). This indicates that Antarctic climate exerts a stronger control on deep flow vigour in the North Atlantic during MIS 3 than Northern Hemisphere climate. The correspondence of SEs with Antarctic warming suggests a weaker WBUC flow due to reduced volume flux at SSW source or reduced SSW density. Because the variability of the lower limb of the WBUC was not connected to sharp North Atlantic changes in temperature, it is unlikely that the Dansgaard/Oeschger cycles were associated with a mode of MOC variation involving wholeocean overturn, but more likely with perturbations of only the shallow Glacial Gulf Stream-Glacial Northern Source Intermediate Water cell. Nutrient proxies (benthic carbon isotopes and Cd/Ca of Uvigerina peregrina) at this site show similar trends to the GRIP delta18O record. This correlation has previously been attributed mainly to hydrographic and flow changes but is here shown to be better explained by variations in surface ocean productivity and subsequent decomposition of 12C rich organic material on the sea floor.

Concentration of the rare-earth elements in metalliferous sediments from DSDP Leg 92 holes

DSDP Leg 92 drilled at four sites along an east-west transect at 19°S on the western flank of the East Pacific Rise (EPR), in an area where sediments are essentially a mixture of hydrothermal and biogenic components, with only a minimal contribution of clastic material. Rare-earth element (REE) data on the metalliferous (non-carbonate) fraction of samples ranging in age from ~2 to ~27 Ma indicate the existence of two distinct groups of patterns corresponding to two broad age groups, one <=8 Ma, the other >=10 Ma. Within each group, REE patterns have characteristics which are near-uniform, despite large variations in total REE abundances. Sediments of the younger group are enriched in light REE (LREE) relative to deep bottom waters influenced by the hydrothermal plume extending west from the EPR at 19°S. Sediments of the older groups show further relative LREE enrichment and/or heavy REE (HREE) depletion. Surficial sediments deposited beneath the lysocline have high Sum REE concentrations resulting from slow accumulation rates, and patterns resembling older sediments due to early diagenetic effects. A correlation between the mass accumulation rates (MAR) of Sum REE and Fe + Mn suggests that ferromanganese particulate matter supplied by the hydrothermal plume scavenges REE; during this process the LREE are preferentially removed from plume seawater. The MAR of Fe + Mn shows a general decrease with age above basement, whereas Sum REE concentrations in the metalliferous component increase with age above basement. This supports the Ruhlin and Owen model wherein limited scavenging of REE, due to rapid burial of sediment near the palaeo-axis, leads to low concentrations (but high MAR-values) for the REE. Following deposition and burial of the hydrothermal component, further relative flattening of the REE pattern takes place, probably the result of diagenetic reactions over several million years. Phase partitioning data indicate that the proportion of REE residing in more poorly crystalline phases tends to increase with age (from ~45% to 90% of Sum REE). This suggests that as initial ferromanganese precipitates undergo diagenetic recrystallization, REE are transferred to the poorly crystalline phases, and/or are scavenged from pore waters by these phases. Because of the various modifications to REE patterns apparently produced both in the water column and post-depositional settings, the REE patterns of metalliferous sediments will not reflect fine-scale REE variations in associated oceanic water masses.

Radiocarbon ages and stable isotope measurements on sediment cores of the subarctic Pacific and its marginal seas

Under modern conditions only North Pacific Intermediate Water is formed in the northwest Pacific Ocean. This situation might have changed in the past. Recent studies with general circulation models indicate a switch to deep-water formation in the northwest Pacific during Heinrich Stadial 1 (17.5-15.0 ka) of the last glacial termination. Reconstructions of past ventilation changes based on paleoceanographic proxy records are still insufficient to test whether a deglacial mode of deep-water formation in the North Pacific Ocean existed. Here we present deglacial ventilation records based on radiocarbon-derived ventilation ages in combination with epibenthic stable carbon isotopes from the northwest Pacific including the Okhotsk Sea and Bering Sea, the two potential source regions for past North Pacific ventilation changes. Evidence for most rigorous ventilation of the intermediate-depth North Pacific occurred during Heinrich Stadial 1 and the Younger Dryas, simultaneous to significant reductions in Atlantic Meridional Overturning Circulation. Concurrent changes in d13C and ventilation ages point to the Okhotsk Sea as driver of millennial-scale changes in North Pacific Intermediate Water ventilation during the last deglaciation. Our records additionally indicate that changes in the d13C intermediate-water (700-1750 m water depth) signature and radiocarbon-derived ventilation ages are in antiphase to those of the deep North Pacific Ocean (>2100 m water depth) during the last glacial termination. Thus, intermediate- and deep-water masses of the northwest Pacific have a differing ventilation history during the last deglaciation.

Palaeolake Rehwiese, NE-Germany, Younger Dryas varved data set RW09

The first 1400-year floating varve chronology for north-eastern Germany covering the late Allerød to the early Holocene has been established by microscopic varve counts from the Rehwiese palaeolake sediment record. The Laacher See Tephra (LST), at the base of the studied interval, forms the tephrochronological anchor point. The fine laminations were examined using a combination of micro-facies and ?-XRF analyses and are typical of calcite varves, which in this case provide mainly a warm season signal. Two varve types with different sub-layer structures have been distinguished: (I) complex varves consisting of up to four seasonal sub-layers formed during the Allerød and early Holocene periods, and, (II) simple two sub-layer type varves only occurring during the Younger Dryas. The precision of the chronology has been improved by varve-to-varve comparison of two independently analyzed sediment profiles based on well-defined micro-marker layers. This has enabled both (1) the precise location of single missing varves in one of the sediment profiles, and, (2) the verification of varve interpolation in disturbed varve intervals in the parallel core. Inter-annual and decadal-scale variability in sediment deposition processes were traced by multi-proxy data series including seasonal layer thickness, high-resolution element scans and total organic and inorganic carbon data at a five-varve resolution. These data support the idea of a two-phase Younger Dryas, with the first interval (12,675 - 12,275 varve years BP) characterised by a still significant but gradually decreasing warm-season calcite precipitation and a second phase (12,275 - 11,640 varve years BP) with only weak calcite precipitation. Detailed correlation of these two phases with the Meerfelder Maar record based on the LST isochrone and independent varve counts provides clues about regional differences and seasonal aspects of YD climate change along a transect from a location proximal to the North Atlantic in the west to a more continental site in the east.

Controls of sediment dynamics on the Galician slope reconstructed from three sediment cores (GeoB11035-1, GeoB130206-1, GeoB13071-1)

Controls of sediment dynamics at the Galician continental slope (NW Iberia) during the past 30 ka were reconstructed from three new gravity cores (GeoB11035-1, 130206-1, 13071-1) based on sedimentological (e.g. sortable silt, IRD), micropalaeontological (e.g. coccoliths), geochemical (AMS 14C, XRF) and geophysical (e.g. magnetic susceptibility) diagnostics. The data are consistent with existing regional knowledge that, during marine isotope stages 3-1, variations in detrital input, marine productivity and sea level were the essential drivers of sediment availability on the slope, whereas deep-water current velocities controlled sediment deposition: (1) the period prior to 30 cal ka BP is characterized by minor but systematic variations in various proxies which can be associated with D-O cycles; (2) between 30 and 18 cal ka BP, high detrital input and steady slope-parallel currents led to constant sedimentation; (3) from the LGM until 10 cal ka BP, the shelf-transgressive sea-level rise increased the detrital particle flux; sedimentation was influenced by significantly enhanced deep-water circulation during the Bølling/Allerød, and subsequent slowing during the Younger Dryas; (4) an abrupt and lasting change to hemipelagic sedimentation at ca. 10 cal ka BP was probably due to Holocene warming and decelerated transgression; (5) after 5 cal ka BP, additional input of detrital material to the slope is plausibly linked to the evolution of fine-grained depocentres on the Galician shelf, this being the first report of this close shelf-slope sedimentary linkage off NW Iberia. Furthermore, there is novel evidence of the nowadays strong outer shelf Iberian Poleward Current becoming established at about 15.5 cal ka BP. The data also demonstrate that small-scale morphologic features and local pathways of sediment export from the neighbouring shelf play an important role for sediment distribution on the NW Iberian slope, including a hitherto unknown sediment conduit off the Ría de Arousa. By implication, the impact of local morphology on along- and down-slope sediment dynamics is more complex than commonly considered, and deserves future attention.

Two pollen profiles of the middle Pleistocene at Samerberg/Upper Bavaria, Germany

Previous pollen analytical studies on sediments from the pleistocene lake basin at Samerberg, situated on the northern edge of the Bavarian Alps (47°45' N, 12°12' E, 607 m a.s.l.) had been performed on samples taken from cores and exposures close to the southern shore of the former lake. After geoelectric and refraction-seismic measurements had shown that the lake basin had been much deeper in its northern part, another core was taken where maximum depth could be expected. The corer penetrated three moraines, two of them lying above pollen-bearing sediments, and one below them, and reached the hard rock (Kössener Kalk) at a depth of 93 m. Two forest phases could be identified by pollen analysis. The pollen record begins abruptly in a forest phase at the end of a spruce-dominated period when fir started to spread (DA 1, DA = pollen zone). Following this, Abies (fir) was the main tree species at Samerberg, Picea being second, and deciduous trees were almost non-existent. First box (Buxus) was of major importance in the fir forests (DA 2), but later on beech (Fagus) and wing-nut (Pterocarya) spread (DA 3). Finally this forest gave way to a spruce forest with pine (DA 4). The beginning and the end of this interglacial cycle are not recorded. Its vegetational development is different from the eemian one known from earlier studies at Samerberg. It is characterized by the occurrence of Abies together with Buxus, Pterocarya and Fagus. A similar association of woody species is known only from the Holsteinian age deposits in an area ranging from England to Poland, though at no other place these species were such important constituents of the vegetation as at Samerberg. Therefore zone 1 to 4 are attributed to the Holsteinian interglacial period. The younger forest phase, separated from the interglacial by a stadial with open vegetation (DA 5), seems to be completely represented, though its sediments are disturbed, apparently by sliding which caused repetition of same-age-sediments in the core (DA 7a, b, c) The vegetational development is simple. A juniper phase (DA 6) was followed by reforestation with spruce, accompanied by some fir (DA 7, 9). Finally pine became the dominant species (DA 9). The simple vegetational development of this younger forest phase does not allow a safe correlation with one of the known pre-eemian interstadials, but for stratigraphical reasons it can be related best to the Dömnitz-interglacial, which among others is also known as Wacken- or Holstein-II-interglacial. Possibly another phase of reforestation is indicated at the end of the following stadial (DA 10). But due to an erosional unconformity nothing than the rise of the juniper curve can be stated. It was only after this sequence of forest phases and periods with open vegetation that glaciers reached the Samerberg area again.

A deep-sea coral record of the North Atlantic

Our record of Younger Dryas intermediate-depth seawater D14C from North Atlantic deep-sea corals supports a link between abrupt climate change and intermediate ocean variability. Our data show that northern source intermediate water (~1700 m) was partially replaced by 14C-depleted southern source water at the onset of the event, consistent with a reduction in the rate of North Atlantic Deep Water formation. This transition requires the existence of large, mobile gradients of D14C in the ocean during the Younger Dryas. The D14C water column profile from Keigwin (2004) provides direct evidence for the presence of one such gradient at the beginning of the Younger Dryas (~12.9 ka), with a 100 per mil offset between shallow (<~2400 m) and deep water. Our early Younger Dryas data are consistent with this profile and also show a D14C inversion, with 35 per mil more enriched water at ~2400 m than at ~1700 m. This feature is probably the result of mixing between relatively well 14C ventilated northern source water and more poorly 14C ventilated southern source intermediate water, which is slightly shallower. Over the rest of the Younger Dryas our intermediate water/deepwater coral D14C data gradually increase, while the atmosphere D14C drops. For a very brief interval at ~12.0 ka and at the end of the Younger Dryas (11.5 ka), intermediate water D14C (~1200 m) approached atmospheric D14C. These enriched D14C results suggest an enhanced initial D14C content of the water and demonstrate the presence of large lateral D14C gradients in the intermediate/deep ocean in addition to the sharp vertical shift at ~2500 m. The transient D14C enrichment at ~12.0 ka occurred in the middle of the Younger Dryas and demonstrates that there is at least one time when the intermediate/deep ocean underwent dramatic change but with much smaller effects in other paleoclimatic records.

Sea surface temperature variations in the western Mediterranean Sea

A high-resolution sea surface temperature (SST) reconstruction of the western Mediterranean was accomplished using two independent, algae-based molecular organic proxies, i.e. the UK'37 index based on long-chain unsaturated ketones and the novel long-chain diol index (LDI) based on the relative abundances of C28 and C30 1,13- and 1,15-diols. Two marine records, from the western and eastern Alboran Sea basin, spanning the last 14 and 20 kyr, respectively, were studied. Results from the surface sediments suggest that the two proxies presently reflect seasons with similar SST, or simply annual mean SST. Both proxy records reveal the transition from the Last Glacial Maximum to the Holocene in the eastern Alboran Sea with an SST increase of ca. 7 °C for UK'37 and 9 °C for LDI. Minimum SSTs (10-12 °C) are reached at the end of the Last Glacial Maximum and during the last Heinrich event with a subsequent rapid SST increase in LDI-SST towards the beginning of the Bölling period (20 °C), while UK'37-SST remains constantly low (~12 °C). The Bölling-Alleröd is characterized by a rapid increase and subsequent decrease in UK'37-SST, while the LDI-SST decrease continuously. Short-term fluctuations in UK'37-SST are probably related to availability of nutrients and seasonal changes. The Younger Dryas is recorded as a short cold interval followed by progressively warmer temperatures. During the Holocene, the general lower UK'37-derived temperature values in the eastern Alboran (by ca. 1.5-2 °C) suggest a southeastward cold water migration by the western Alboran gyre and divergence in the haptophyte blooming season between both basins.

Tab. 1: Radiocarbon ages of the late Pleistocene and early Holocene of Mecklenburg-Vorpommern and surrounding areas

Several geoscientific projects in the last decade led to a marked increase of radiocarbon dates in Mecklenburg-Vorpommern and in neighbouring areas. The studies were mostly focussed on the genesis of the Baltic Basin and the last termination. In this Paper, a regional collection of 271 radiocarbon dates of the late Pleistocene and early Holocene (ca. 50,000-8,000 14C yr BP) is presented. The dates were calibrated, correlate, and assessed with regard to their credibility. The evaluation of the data is focussed on problems of regional palaeogeography. The age of the last Weichselian deglaciation (deglaciation after the Mecklenburg Advance) is assumed to be around 14,000 14C yr BP through radiocarbon dates from the Pomeranian Bay. This data is ca. 1,000 years older compared to former views. On the other hand, the database allows the dating of late Pleistocene basin sequences from the Baltic coast, This indicates three stratigraphic units for basin areas 0-15 m above sea level - glaciolacustrine sedimentation in the late Pleniglacial, lacustrine and telmatic sedimentation as well as soil formation in the early Lateglacial and Alleroed and aeolian sedimentation in the Younger Dryas. The Younger Dryas in the huge Mecklenburg Bay-Darss Basin NE of Rostock is characterised by lacustrine sedimentation ca. 20 m below sea level ("Baltic Ice Lake"), and by aeolian sedimentation above sea level.