Showing papers by "Geological Survey of Denmark and Greenland published in 2005"

Quality assurance in model based water management - review of existing practice and outline of new approaches

Abstract: Quality assurance (QA) is defined as protocols and guidelines to support the proper application of models. In the water management context we classify QA guidelines according to how much focus is put on the dialogue between the modeller and the water manager as: (Type 1) Internal technical guidelines developed and used internally by the modeller's organisation; (Type 2) Public technical guidelines developed in a public consensus building process; and (Type 3) Public interactive guidelines developed as public guidelines to promote and regulate the interaction between the modeller and the water manager throughout the modelling process. State-of-the-art QA practices vary considerably between different modelling domains and countries. It is suggested that these differences can be explained by the scientific maturity of the underlying discipline and differences in modelling markets in terms of volume of jobs outsourced and level of competition. The structure and key aspects of new generic guidelines and a set of electronically based supporting tools that are under development within the HarmoniQuA project are presented. Model credibility can be enhanced by a proper modeller-manager dialogue, rigorous validation tests against independent data, uncertainty assessments, and peer reviews of a model at various stages throughout its development.

Regional spread and stand-scale establishment of fagus sylvatica and picea abies in scandinavia

Abstract: Palaeoecological studies are yielding fresh insights into slow forest ecosystem processes that are rarely observed using standard ecological methods, yet have major impacts on ecosystem function. Regional pollen data describe the broad features of the regional spread of trees but yield few insights into the processes of stand invasion and the facilitating role of disturbance. Pollen and charcoal data from small forest hollows are used to complement regional data in the study of the spread of Picea abies and Fagus sylvatica into southern Scandinavia during the last 4000 years. P. abies spread as a migrating front and preferentially invaded successional Betula stands, which had become particularly widespread in the region during the last 1000 years as a result of human activity. The spread of P. abies also closely tracked the changing area of suitable regional climate. The spread of F. sylvatica was more directly linked to anthropogenic activities and disturbance by fire prior to stand establishment. F. sylvatica preferentially invaded rich deciduous stand types that had declined in abundance during the last 2000 years. A recent range reduction of F. sylvatica can also be ascribed to human activity. The stand-scale palaeoecological data show how site conditions and disturbance are more important rate-limiting factors for F. sylvatica than for P. abies and help explain why F. sylvatica spread shows a patchy dynamic rather than the smoother migrating front of P. abies.

Leaching of glyphosate and amino-methylphosphonic acid from Danish agricultural field sites.

Abstract: Pesticide leaching is an important process with respect to contamination risk to the aquatic environment. The risk of leaching was thus evaluated for glyphosate (N-phosphonomethyl-glycine) and its degradation product AMPA (amino-methylphosphonic acid) under field conditions at one sandy and two loamy sites. Over a 2-yr period, tile-drainage water, ground water, and soil water were sampled and analyzed for pesticides. At a sandy site, the strong soil sorption capacity and lack of macropores seemed to prevent leaching of both glyphosate and AMPA. At one loamy site, which received low precipitation with little intensity, the residence time within the root zone seemed sufficient to prevent leaching of glyphosate, probably due to degradation and sorption. Minor leaching of AMPA was observed at this site, although the concentration was generally low, being on the order of 0.05 microg L(-1) or less. At another loamy site, however, glyphosate and AMPA leached from the root zone into the tile drains (1 m below ground surface [BGS]) in average concentrations exceeding 0.1 microg L(-1), which is the EU threshold value for drinking water. The leaching of glyphosate was mainly governed by pronounced macropore flow occurring within the first months after application. AMPA was frequently detected more than 1.5 yr after application, thus indicating a minor release and limited degradation capacity within the soil. Leaching has so far been confined to the depth of the tile drains, and the pesticides have rarely been detected in monitoring screens located at lower depths. This study suggests that as both glyphosate and AMPA can leach through structured soils, they thereby pose a potential risk to the aquatic environment.

Geological development of the Northeast Greenland Shelf

Abstract: Seismic data from the East Greenland shelf show that the northern part of the shelf, north of 75°N, can be subdivided into five, roughly northeast-trending, major tectonic elements. From west to east they are: the Koldewey Platform, the Danmarkshavn Basin, the Danmarkshavn Ridge, the Thetis Basin and the Marginal High. A sixth tectonic element, the Shannon High, has been defined in the southern part of this area. The offshore areas between 72°30′N and 75°N are dominated by Tertiary plateau basalts, which obscure the acoustic signals from the deeper sedimentary succession. Seismic data from the area north of 75°N indicate the presence of a fairly complete succession of ? Devonian to Neogene age, exceeding the recorded interval (8 sec TWT – 13 km) in thickness in the deeper parts of the Danmarkshavn Basin. The succession has been subdivided into 15 seismic mega-sequences. In absence of well control, they have been dated by comparison to the onshore successions of East Greenland and eastern North Greenland, and the offshore successions in the southern Barents Sea and on the mid-Norwegian shelf. The Upper Palaeozoic succession is broadly similar to that of the southern Barents Sea, i.e. marine-dominated, with thick Upper Carboniferous–Lower Permian halite deposits in the northern Danmarkshavn Basin. The Mesozoic succession seems to show greater similarities to the onshore basins of East Greenland: rifting started during the mid-Jurassic and peaked near the Jurassic–Cretaceous boundary. The post-volcanic succession reflects deposition on a passive margin subjected to temporary uplift during the early Miocene and the latest Miocene to earliest Pliocene.

Estimating relevant source area of pollen for small Danish lakes around AD 1800

Abstract: The aims of this study were to obtain estimates of the relevant source area of pollen (RSAP) that can be used to interpret fossil pollen diagrams from medium sized lakes, and to elucidate factors affecting RSAP for such lakes. A data set of sediment pollen assemblages dating from AD 1800 from 25 Danish lakes (3-27 ha) and land cover around the same lakes from historical maps was used. The plant abundance data were distance weighted using a species-specific model of pollen dispersal/deposition and other distance weighting functions (1, Ild and lId2). Extended R-value models were applied to evaluate the relationship between pollen and plant abundance and to estimate RSAP. The choice of distance weighting function influenced the RSAP estimates. When using the species-specific model, wind speed and species-specific properties of pollen dispersal had little effect on the RSAP estimates, which were approximately 1700 m in radius, when all lakes were analysed together. When the pollen types were classified into ...

PAH degradation capacity of soil microbial communities--does it depend on PAH exposure?

Abstract: Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous pollutants of the environment. But is their microbial degradation equally wide in distribution? We estimated the PAH degradation capacity of 13 soils ranging from pristine locations (total PAHs ≈ 0.1 mg kg−1) to heavily polluted industrial sites (total PAHs ≈ 400 mg kg−1). The size of the pyrene- and phenanthrene-degrading bacterial populations was determined by most probable number (MPN) enumeration. Densities of phenanthrene degraders reflected previous PAH exposure, whereas pyrene degraders were detected only in the most polluted soils. The potentials for phenanthrene and pyrene degradation were measured as the mineralization of 14C-labeled spikes. The time to 10% mineralization of added 14C phenanthrene and 14C pyrene was inversely correlated with the PAH content of the soils. Substantial 14C phenanthrene mineralization in all soils tested, including seven unpolluted soils, demonstrated that phenanthrene is not a suitable model compound for predicting PAH degradation in soils. 14C pyrene was mineralized by all Danish soil samples tested, regardless of whether they were from contaminated sites or not, suggesting that in industrialized areas the background level of pyrene is sufficient to maintain pyrene degradation traits in the gene pool of soil microorganisms. In contrast, two pristine forest soils from northern Norway and Ghana mineralized little 14C pyrene within the 140-day test period. Mineralization of phenanthrene and pyrene by all Danish soils suggests that soil microbial communities of inhabited areas possess a sufficiently high PAH degradation capacity to question the value of bioaugmentation with specific PAH degraders for bioremediation.

Neogene evolution of the Atlantic continental margin of NW Europe (Lofoten Islands to SW Ireland): anything but passive

Abstract: A regional stratigraphic framework for the Neogene succession along and across the NW European margin is presented, based on a regional seismic and sample database. The stratigraphy provides constraints on the timing and nature of the mid- to late Cenozoic differential tectonic movements that have drivenmajor changes in sediment supply, oceanographic circulation and climate (culminating in continental glaciation). The overall context for Neogene deposition on the margin was established in the mid-Cenozoic, when rapid, km-scale differential subsidence (sagging) created the present-day deep-water basins. The Neogene is subdivided into lower (Miocene–lower Pliocene) and upper (lower Pliocene–Holocene) intervals. The lower Neogene contains evidence of early to mid-Miocene compressive tectonism, including inversion anticlines and multiple unconformities that record uplift and erosion of basin margins, as well as changes in deep-water currents. These movements culminated in a major expansion of contourite drifts in the mid-Miocene, argued to reflect enhanced deep-water exchange across the Wyville-Thomson Ridge Complex, via the Faroe Conduit. The distribution and amplitude of the intra-Miocene movements are consistent with deformation and basin margin flexure in response to enhanced intra-plate compressive stresses during a local plate reorganization (transfer of the Jan Mayen Ridge from Greenland to Europe). The upper Neogene records a seaward tilting (

Separation of Palaeogene and Neogene uplift on Nuussuaq, West Greenland

Abstract: The geological record exposed on Nuussuaq, central West Greenland, shows that uplift in the Palaeocene, probably caused by impact of the Iceland plume head, was followed by kilometre-scale subsidence. Analysis of apatite fission-track and vitrinite-reflectance data from borehole samples down to 3 km depth reveals that the samples cooled from maximum palaeotemperatures between 40 and 30 Ma followed by two further cooling episodes beginning in the intervals 11–10 and 7–2 Ma. When the first cooling episode began, the samples from the neighbouring Gro-3 and Gane-1 boreholes were buried 1500–2000 m deeper than at the present day, and the palaeogeothermal gradient was 40–48 °C km −1 . It is not clear whether this cooling involved exhumation or if it was due solely to reduction in heat flow and a drop in surface temperature. The two later episodes definitely involved exhumation because by then the palaeogeothermal gradient had declined to a value close to the assumed present value of 30 °C km −1 , which agrees with estimates from offshore wells. The most recent cooling episode corresponds to the incision of the present-day relief ( c . 1100 m) below the summits around the two boreholes. We conclude that the present-day high mountains of West Greenland were not uplifted during the Palaeogene, but are erosional remnants of a landmass uplifted during the Neogene.

Mid-to late-Holocene land-use change and lake development at Dallund S0, Denmark: synthesis of multiproxy data, linking land and lake

Abstract: Multiproxy palaeoecological data for lake Dallund S0, Denmark, were synthesized to explore the link between changes in the terrestrial environment (from pollen, and sediment physical properties) with those in the aquatic environment (from diatom, macrofossil, zooplankton and Pediastrum data) since the introduction of agriculture c 6000 years ago The lake was relatively insensitive to catchment disturbance during the Neolithic (3870-1700 BC) and Early Bronze Age (1700-1000 BC) periods but was dramatically impacted by environmental changes associated with a major deforestation phase at the transition from the Late Bronze Age (1000-500 BC) to the Pre-Roman Iron Age (500 BC-AD 0) A major eutrophication of the lake took place as a result of a changing agricultural system and also the retting of flax and hemp during the Mediaeval period (AD 1050-1536) Analyses of the data sets representing the terrestrial and aquatic environments demonstrate that human activities over thousands of years have not only impact

Elucidating the Key Member of a Linuron-Mineralizing Bacterial Community by PCR and Reverse Transcription-PCR Denaturing Gradient Gel Electrophoresis 16S rRNA Gene Fingerprinting and Cultivation

Abstract: The phenylurea herbicide linuron [N-(3,4-dichlorophenyl)-N′-methoxy-N′-methylurea] is used worldwide in the conventional production of corn, cereals, vegetables, and fruit. The rates of dissipation in agricultural soils determined by laboratory and field experiments are highly variable, with values ranging from days to several years (2, 8, 9, 11, 16, 23). Linuron is frequently detected in surface and ground waters near or below areas with intensive use, and in one extreme case, linuron was detected in a drinking-water well in concentrations up to 2,800 μg liter−1 (2). Unfortunately, linuron and some of its metabolites are suspected of being endocrine disruptors (12) and of having toxic effects on various aquatic and soil organisms (2, 22), which has stimulated research aimed at studying linuron-mineralizing microorganisms from agricultural soils. Mixed bacterial cultures able to mineralize linuron have been derived from extensively treated British and Belgian agricultural soils (4, 7, 15). Similar enrichments based on related phenylurea herbicides (1, 3, 6, 19) suggest that this group can serve as carbon and nitrogen sources for bacterial metabolism in agricultural soils. Several attempts to cultivate phenylurea-metabolizing soil bacteria from degradative enrichment cultures, however, were unsuccessful (e.g., studies described in references 7, 15, and 18), and the active bacteria seem reluctant to grow on agar media. Recently, however, the first linuron-mineralizing bacterium, Variovorax sp. strain WDL1 (4), was isolated from previously treated Belgian agricultural soil. Strain WDL1 appeared to be an ineffective linuron degrader in pure culture and dependent on four other consortium members (4). The phenomenon of synergistic bacterial interactions has also been described for the herbicide isoproturon (19, 20). An extensively linuron-treated Danish agricultural field harboring a potential for rapid linuron mineralization was located among three investigated fields. The objective of this study was to obtain linuron-mineralizing enrichment cultures and pinpoint degradative microorganisms by molecular and cultivation-based techniques.

Ultrasonic velocities of North Sea chalk samples: influence of porosity, fluid content and texture

Abstract: We have studied 56 unfractured chalk samples of the Upper Cretaceous Tor Formation of the Dan, South Arne and Gorm Fields, Danish North Sea. The samples have porosities of between 14% and 45% and calcite content of over 95%. The ultrasonic compressional- and shear-wave velocities (VP and VS) for dry and water-saturated samples were measured at up to 75 bar confining hydrostatic pressure corresponding to effective stress in the reservoir. The porosity is the main control of the ultrasonic velocities and therefore of the elastic moduli. The elastic moduli are slightly higher for samples from the South Arne Field than from the Dan Field for identical porosities. This difference may be due to textural differences between the chalk at the two locations because we observe that large grains (i.e. filled microfossils and fossil fragments) that occur more frequently in samples from the Dan Field have a porosity-reducing effect and that samples rich in large grains have a relatively low porosity for a given P-wave modulus. The clay content in the samples is low and is mainly represented by either kaolinite or smectite; samples with smectite have a lower P-wave modulus than samples with kaolinite at equal porosity. We find that ultrasonic VP and VS of dry chalk samples can be satisfactorily estimated with Gassmann's relationships from data for water-saturated samples. A pronounced difference between the VP/VS ratios for dry and water-saturated chalk samples indicates promising results for seismic amplitude-versus-offset analyses.

Mid- to late-Holocene land-use change and lake development at Dallund Sø, Denmark: trends in lake primary production as reflected by algal and macrophyte remains

Abstract: Diatom, macrofossil, pollen, Pediastrum and biogenic silica analyses were carried out on an 11-m sediment sequence from the Danish lake Dallund So, demonstrating major changes in the aquatic ecosystem over the last 7000 years. A diatom-phosphorus calibration model was applied to the fossil diatom record to reconstruct in-lake total phosphorus (TP) concentrations over this period. Prior to the introduction of agriculture to the region, c. 6000 years ago, the lake was relatively deep and had low diatom-inferred TP concentrations (c. 20 υg TP/L), with limited macrophyte growth. Moderate nutrient enrichment of the lake was inferred during the Bronze Age (1700-500 Bc) and Iron Age (500 BC-AD 1050) periods and evidence for water-level lowering was observed. Marked eutrophication of the lake (reconstructed TP levels consistently > 100 υg/L) was associated with major changes in agriculture during the Mediaeval period (AD 1050-1536) and continued to the present day. These data document the long-term anthropogenic ...

Structural analysis of the rubjerg Knude Glaciotectonic Complex, Vendsyssel, northern Denmark

Abstract: Pedersen, S.A.S. 2005: Structural analysis of the Rubjerg Knude Glaciotectonic Complex, Vendsyssel, northern Denmark. Geological Survey of Denmark and Greenland Bulletin 8, 192 pp. The Rubjerg Knude Glaciotectonic Complex is a thin-skinned thrust-fault complex that was formed during the advance of the Scandinavian Ice Sheet (30 000 – 26 000 B.P.); it is well exposed in a 6 km long coastal profile bordering the North Sea in northern Denmark. The glaciotectonic thrust-fault deformation revealed by this cliff section has been subjected to detailed structural analysis based on photogrammetric measurement and construction of a balanced cross-section. Thirteen sections are differentiated, characterising the distal to proximal structural development of the complex. The deformation affected three stratigraphic units: the Middle Weichselian arctic marine Stortorn Formation, the mainly glaciolacustrine Lonstrup Klint Formation and the dominantly fluvial Rubjerg Knude Formation; these three formations are formally defined herein, together with the Skaerumhede Group which includes the Stortorn and Lonstrup Klint Formations. The Rubjerg Knude Formation was deposited on a regional unconformity that caps the Lonstrup Klint Formation and separates pre-tectonic deposits below from syntectonic deposits above. In the distal part of the complex, the thrust-fault architecture is characterised by thin flatlying thrust sheets displaced over the footwall flat of the foreland for a distance of more than 500 m. Towards the proximal part of the complex, the dip of the thrust faults increases, and over long stretches they are over-steepened to an upright position. The lowest decollement zone is about 40 m below sea level in the proximal part of the system, and shows a systematic step-wise change to higher levels in a distal (southwards) direction. The structural elements are ramps and flats related to hanging-wall and footwall positions. Above upper ramp-hinges, hanging-wall anticlines developed; footwall synclines are typically related to growth-fault sedimentation in syntectonic piggyback basins, represented by the Rubjerg Knude Formation. Blocks and slump-sheets constituting parts of the Lonstrup Klint Formation were derived from the tips of up-thrusted thrust sheets and slumped into the basins. Mud diapirs are a prominent element in the thrust-fault complex, resulting from mud mobilisation mainly at hanging-wall flats and ramps. Shortening during thrust-fault deformation has been calculated as 50%. Only about 11% of the initial stratigraphic units subjected to thrust faulting has been lost due to erosion. The thrust-fault deformation was caused by gravity spreading of an advancing ice sheet. Overpressured mud-fluid played an important role in stress transmission. The average velocity of thrust-fault displacement is estimated at 2 m per year, which led to compression of a 12 km stretch of flat-lying sediments, c. 40 m in thickness, into a thrust-fault complex 6 km in length. The thrust-fault complex is truncated by a glaciotectonic unconformity, formed when the advancing ice sheet finally overrode the complex. When this ice sheet melted away, a hilland- hole pair was formed, and meltwater deposits derived from a new ice-advance (NE-Ice) filled the depression. The NE-Ice overran the complex during its advance to the main stationary line situated in the North Sea. When this ice in turn melted away (c. 19 000 – 15 000 B.P.), the glacial landscape was draped by arctic marine deposits of the Vendsyssel Formation (new formation defined herein).

Natural and anthropogenic forcing of aquatic macrophyte development in a shallow Danish lake during the last 7000 years

Abstract: Aim To investigate the long-term changes in aquatic vegetation in a lowland, shallow lake, and to assess the relationship between aquatic vegetation and natural and anthropogenic catchment changes. Location Gundsomagle So, Zealand, Denmark: a shallow (mean depth 1.2 m), hypereutrophic lake (mean annual total phosphorus (TP) c. 700 μg TP L−1) located in a predominantly agricultural catchment (88% cultivated land). The lake is presently devoid of macrophytes. Methods One hundred and forty-seven contiguous samples from a sediment core (taken in 2000) were analysed for macrofossil remains together with loss-on-ignition and dry weight. From an earlier sediment core (taken in 1992), 67 samples were analysed for pollen and the two cores were correlated using the ignition residue profiles. Core chronology was determined by 210Pb and 137Cs dating of the recent lake sediments, while older sediments were dated by pollen-stratigraphical correlation, as 14C dating proved problematical. Aquatic macrofossil abundance was used to reconstruct past changes in the lake's plant community and water-level. The contemporary catchment land-use change was inferred from sedimentary pollen data, and soil erosion to the lake was deduced from the minerogenic content of the lake sediments. Results The macrofossil record covers the last 7000 years, but aquatic plant remains were scarce prior to c. 1300 bc. After this date the abundance of submerged and emergent macrophyte remains increased dramatically, paralleled by an increase in sediment minerogenic matter and non-arboreal pollen (NAP). Aquatic plant remains were abundant for more than 3000 years until the mid 1900s. Macrofossils of Linum usitatissimum (L.) (flax) and high pollen percentages of ‘Cannabis type’ (hemp) were recorded in periods between c. 1150 bc and 1800 ad. Main conclusions Our study suggests that, between c. 5000 bc and 1300 bc, the submerged plant community was confined to the littoral zone. From 1300 bc onwards, the submerged macrophyte vegetation expanded rapidly across the lake bed, presumably as a response to lake shallowing caused by a combination of climatic-induced water-level lowering and enhanced erosional infilling of the lake basin due to intensified anthropogenic activities in the catchment. The lake was meso-eutrophic and had an extensive and diverse aquatic flora for more than 3000 years, until the middle of the twentieth century. In periods between c. 1150 bc and 1800 ad, the lake experienced direct anthropogenic impact from retting of fibre plants (Linum and Cannabis). Over the last 200 years, erosional infilling of the lake basin increased drastically, probably as a result of agricultural intensification. In the twentieth century, the lake was strongly affected by nutrient enrichment from both point sources (sewage from built-up areas) and diffuse agricultural run-off which led to hypertrophic conditions and the collapse of the submerged vegetation c. 1950–60. The concept of ‘naturalness’ and the implications for lake conservation are discussed.

The Mesoproterozoic Zig-Zag Dal basalts and associated intrusions of eastern North Greenland: mantle plume–lithosphere interaction

Abstract: The lavas of the Zig-Zag Dal Formation of eastern North Greenland constitute a Mesoproterozoic tholeiitic flood basalt succession up to 1,350 m thick, extending >10,000 km2, and underlain by a sill complex. U–Pb dating on baddeleyite from one of the sills thought to be contemporaneous with the lava extrusion, gives an age of 1,382±2 Ma. The lavas, subdivided from oldest to youngest into Basal, Aphyric and Porphyritic units, are dominantly basaltic (>6 wt.% MgO), with more evolved lavas occurring within the Aphyric unit. The most magnesian lavas occur in the Basal unit and the basaltic lavas exhibit a generalised upward decrease in Mg number (MgO/(MgO + Fe2O 3 T )) through the succession. All of the lavas are regarded as products of variable degrees of olivine, augite and plagioclase fractionation and to be residual after generation of cumulates in the deep crust. The basaltic lavas display an up-section fall in the ratio of light to heavy rare-earth elements (LREE/HREE) but an up-section rise in Zr/Nb, Sc, Y and HREE. The older lavas (Basal and Aphyric units) are characterised by low ɛNd and ɛHf in contrast to higher values in the younger (Porphyritic unit) lavas. The Porphyritic Unit basalts are characterised by a notable enrichment in Fe and Ti. The Zig-Zag Dal succession is inferred to reflect an increase in melt fraction in the sub-lithospheric mantle, with melting commencing in garnet–lherzolite facies peridotites and subsequently involving spinel-facies mantle at increasingly shallow depths. Melting is deduced to have occurred beneath an attenuating continental lithosphere in conjunction with ascent of a mantle plume. Lithospheric contamination of primitive melts is inferred to have diminished with time with the Porphyritic unit basalts being products of essentially uncontaminated plume-source magmas. The high iron signature may reflect a relatively iron-rich plume source.

Vegetation history in western Uganda during the last 1200 years: a sedimentbased reconstruction from two crater lakes:

Abstract: Pollen, plant macrofossil and charcoal records from two neighbouring crater lakes (Lake Wandakara and Lake Kasenda) in lower montane (altitude-1200m) western Uganda (0.5DN, 30) reveal major changes...

Mid-to late-Holocene land-use change and lake development at Dallund S0, Denmark: vegetation and land-use history inferred from pollen data:

Abstract: Pollen and plant macrofossil analysis of an 11-m sediment core from Dallund So, a lake situated in the plains of north Funen, Denmark, provide a record of the last 7000 years of vegetation history in response to changing land-use practices. Around 3900 BC, a distinct Ulmus decline is registered. The first agricultural activity is evidenced c. 400 years after the elm decline by the occurrence of cereal pollen (AvenalTriticum-type). Shortly after this, the Neolithic ‘landnam’ sensu Iversen was detected. Around the transition Late Bronze Age/Pre-Roman Iron Age (500 BC), extensive forest clearances followed by a major expansion of grazing areas, cultivated fields and meadows was inferred. The immigration time of Fagus is hard to identify but a threshold percentage > 2 was reached c. 700 BC, suggesting a local presence of Fagus woodland by then. In the Late Iron Age (AD 400-AD 1050), rising abundances of cereal and Cannabis-type pollen indicate increased arable farming. A contemporary Fagus/Quercus woodland ex...