105 results
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102. Weichselian before 15,000 years B.P. in the Nordic countries: a symposium
- Author
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Jan Mangerud
- Subjects
Archeology ,Series (stratigraphy) ,Paleontology ,geography ,geography.geographical_feature_category ,law ,Geology ,Radiocarbon dating ,Ice sheet ,Ecology, Evolution, Behavior and Systematics ,law.invention - Abstract
The symposium, arranged in 1980 in Bergen, was the last in a series of three symposia on Weichselian events in the Scandinavian realm. Papers from the two earlier symposia were published in Boreas 8:2 (1979) and 9:4 (1980). Recent research has proved the history of the Scandinavian Ice Sheet to be more complicated than formerly thought. One problem relating to this research is dating beyond the limit of the radiocarbon method
- Published
- 2008
103. Interstadial and last interglacial deposits covered by till in Scotland: a reply
- Author
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J. Brian Sissons
- Subjects
Archeology ,law ,Interpretation (philosophy) ,Interglacial ,Geology ,Stadial ,Radiocarbon dating ,Archaeology ,Ecology, Evolution, Behavior and Systematics ,law.invention - Abstract
Caseldine & Edwards (Boreas, Vol. 11, pp. 119–122) have misrepresented assessments of published evidence in the paper by Sissons 1981 (Boreas, Vol. 10, No. 1). They have not used radiocarbon dates objectively and argue illogically. A different interpretation for the Teindland site is suggested.
- Published
- 2008
104. Late Pleistocene to Holocene vegetation and climate changes in northwestern Chukotka (Far East Russia) deduced from lakes Ilirney and Rauchuagytgyn pollen records
- Author
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Kathleen R. Stoof-Leichsenring, Boris K. Biskaborn, Andrei Andreev, Thomas Böhmer, Stefan Kruse, Ulrike Herzschuh, Stuart Andrew Vyse, Elena Raschke, Lyudmila Pestryakova, Jeremy Courtin, Andreev, Andrei A., 1Alfred Wegener InstituteHelmholtz Centre for Polar and Marine Research, Telegrafenberg A43 Potsdam 14473 Germany, Raschke, Elena, Biskaborn, Boris K., Vyse, Stuart A., Courtin, Jeremy, Böhmer, Thomas, Stoof‐Leichsenring, Kathleen, Kruse, Stefan, Pestryakova, Lyudmila A., 2Department of Geography and Biology North‐Eastern Federal University Belinsky St. 58 Yakutsk 677000 Russia, and Herzschuh, Ulrike
- Subjects
010506 paleontology ,Archeology ,010504 meteorology & atmospheric sciences ,Pleistocene ,Climate change ,medicine.disease_cause ,01 natural sciences ,Late Pleistocene ,Pollen ,medicine ,Ecology, Evolution, Behavior and Systematics ,Holocene ,0105 earth and related environmental sciences ,pollen stratigraphy ,arctic Chukotka ,Geology ,15. Life on land ,lacustrine sediments ,climate change ,13. Climate action ,Physical geography ,medicine.symptom ,Vegetation (pathology) ,Far East - Abstract
This paper presents two new pollen records and quantitative climate reconstructions from northern Chukotka documenting environmental changes over the last 27.9 ka. Open tundra‐ and steppe‐like habitats dominated between 27.9 and 18.7 cal. ka BP. Betula and Alnus shrubs might have grown in sheltered microhabitats but disappeared after 18.7 cal. ka BP. Although the climate was rather harsh, local herb‐dominated communities supported herbivores as is evident by the presence of coprophilous spores in the sediments. The increase in Salix and Cyperaceae ~16.1 cal. ka BP suggests climate amelioration. Shrub Betula appeared ~15.9 cal. ka BP, and became dominant after ~15.52 cal. ka BP, whilst typical steppe communities drastically reduced. Very high presence of Botryococcus in the Lateglacial sediments reflects widespread shallow habitats, probably due to lake level increase. Shrub Alnus became common after ~13 cal. ka BP reflecting further climate amelioration. Simultaneously, herb communities gradually decreased in the vegetation reaching a minimum ~11.8 cal. ka BP. A gradual decrease of algae remains suggests a reduction of shallow‐water habitats. Shrubby and graminoid tundra was dominant ~11.8–11.1 cal. ka BP, later Salix stands significantly decreased. The forest‐tundra ecotone established in the Early Holocene, shortly after 11.1 cal. ka BP. Low contents of green algae in the Early Holocene sediments likely reflect deeper aquatic conditions. The most favourable climate conditions were between ~10.6 and 7 cal. ka BP. Vegetation became similar to the modern after ~7 cal. ka BP but Pinus pumila came to the Ilirney area at about 1.2 cal. ka BP. It is important to emphasize that the study area provided refugia for Betula and Alnus during MIS 2. It is also notable that our records do not reflect evidence of Younger Dryas cooling, which is inconsistent with some regional environmental records but in good accordance with some others., European Research Council
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105. [Untitled]
- Subjects
010506 paleontology ,Archeology ,geography ,geography.geographical_feature_category ,010504 meteorology & atmospheric sciences ,Glacial landform ,Bedrock ,Drumlin ,Geology ,01 natural sciences ,Moraine ,Glacial period ,Ice sheet ,Meltwater ,Scale (map) ,Cartography ,Ecology, Evolution, Behavior and Systematics ,0105 earth and related environmental sciences - Abstract
During the last glaciation, most of the British Isles and the surrounding continental shelf were covered by the British–Irish Ice Sheet (BIIS). An earlier compilation from the existing literature (BRITICE version 1) assembled the relevant glacial geomorphological evidence into a freely available GIS geodatabase and map (Clark et al. 2004: Boreas 33, 359). New high-resolution digital elevation models, of the land and seabed, have become available casting the glacial landform record of the British Isles in a new light and highlighting the shortcomings of the V.1 BRITICE compilation. Here we present a wholesale revision of the evidence, onshore and offshore, to produce BRITICE version 2, which now also includes Ireland. All published geomorphological evidence pertinent to the behaviour of the ice sheet is included, up to the census date of December 2015. The revised GIS database contains over 170 000 geospatially referenced and attributed elements – an eightfold increase in information from the previous version. The compiled data include: drumlins, ribbed moraine, crag-and-tails, mega-scale glacial lineations, glacially streamlined bedrock (grooves, roches moutonnees, whalebacks), glacial erratics, eskers, meltwater channels (subglacial, lateral, proglacial and tunnel valleys), moraines, trimlines, cirques, trough-mouth fans and evidence defining ice-dammed lakes. The increased volume of features necessitates different map/database products with varying levels of data generalization, namely: (i) an unfiltered GIS database containing all mapping; (ii) a filtered GIS database, resolving data conflicts and with edits to improve geo-locational accuracy (available as GIS data and PDF maps); and (iii) a cartographically generalized map to provide an overview of the distribution and types of features at the ice-sheet scale that can be printed at A0 paper size at a 1:1 250 000 scale. All GIS data, the maps (as PDFs) and a bibliography of all published sources are available for download from: https://www.sheffield.ac.uk/geography/staff/clark_chris/britice.
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