scholarly journals Vegetation variability in Greece during the last interglacial

2000 ◽  
Vol 79 (2-3) ◽  
pp. 355-367 ◽  
Author(s):  
P.C. Tzedakis
Keyword(s):  
Late Glacial ◽  
Climatic Conditions ◽  
Last Interglacial ◽  
Regional Variability ◽  
Vegetation Development ◽  
Mixed Forests ◽  
Common Features ◽  
Central Greece ◽  
Environmental Setting ◽  
Short Episode

AbstractThe extent of regional variability in vegetation development in mainland Greece during the last interglacial is considered. Three pollen sequences – Ioannina (northwest Greece),Tenaghi Philippon (northeast Greece) and Kopais (central Greece) – all located in different environmental settings, extend into the last interglacial. Examination of the vegetation histories of the three sites during the last interglacial reveals the influence of local climatic conditions with closed mixed forests in the northwest, becoming progressively more open and less diverse farther to the east and south. All three sequences contain a number of similar trends, however, in the expansion of certain taxa. In addition, they also show the presence of a two-step late glacial interval, a short episode of forest reduction in the second part of the interglacial and a final small expansion of tree populations at the very end of the interglacial. Comparison with other European records shows a number of common features, but also suggests differences consistent with the particular environmental setting of the Greek sites.

Late-glacial and Post-glacial history of the Chalk escarpment near Brook, Kent

1964 ◽  
Vol 248 (745) ◽  
pp. 135-204 ◽  
Keyword(s):  
Bronze Age ◽  
Iron Age ◽  
Late Glacial ◽  
Climatic Conditions ◽  
Valley Floor ◽  
Glacial Period ◽  
Late Neolithic ◽  
Local Conditions ◽  
Arable Farming ◽  
History Of

This paper describes the morphology of a small piece of the Chalk escarpment near Brook in east Kent, and reconstructs its history since the end of the Last Glaciation. The escarpment contains a number of steep-sided valleys, or coombes, with which are associated deposits of chalk debris, filling their bottoms and extending as fans over the Gault Clay plain beyond. Here the fans overlie radiocarbon-dated marsh deposits of zone II (10 000 to 8800 B.C.) of the Late-glacial Period. The debris fans were formed and the coombes were cut very largely during the succeeding zone III (8800 to 8300 B.C.). The fans are the products of frost-shattering, probably transported by a combination of niveo-fluvial action and the release of spring waters; intercalated seams of loess also occur. The molluscs and plants preserved in the Late-glacial deposits give a fairly detailed picture of local conditions. The later history of one of the coombes, the Devil’s Kneadingtrough, is reconstructed. The springs have effected virtually no erosion and have probably always emerged more or less in their present position. In the floor of the coombe the periglacial chalk rubbles of zone III are covered by Postglacial deposits, mainly hillwashes. They are oxidized and yield no pollen, but contain rich faunas of land Mollusca, which are presented in the form of histograms revealing changing local ecological and climatic conditions. During most of the Post-glacial Period, from the end of zone III until about the beginning of zone VIII, very little accumulation took place on the coombe floor. But below the springs there are marsh deposits which span much of this interval. They yield faunas of considerable zoogeographical interest. The approximate beginning of zone VII a (Atlantic Period) is reflected by a calcareous tufa, which overlies a weathering horizon, and represents an increase in spring flow. Two clearance phases are deduced from the molluscan record. The first may have taken place at least as early as the Beaker Period (Late Neolithic/earliest Bronze Age); the second is probably of Iron Age ‘A’ date. In Iron Age times the subsoil was mobilized and a phase of rapid hillwashing began. As a result the valley floor became buried by humic chalk muds. The prime cause of this process was probably the beginning of intensive arable farming on the slopes above the coombe; a possible subsidiary factor may have been the Sub-Atlantic worsening of climate. The muds yield pottery ranging in date from Iron Age ‘Kentish first A’ ( ca . 500 to ca . 300 B.C.) to Romano-British ware of the first or second centuries A.D. Evidence is put forward for a possible climatic oscillation from dry to wet taking place at about the time of Christ. In the later stages of cultivation, possibly in the Roman Era, the valley floor was ploughed and given its present-day form.

Late-Glacial Cooling in Amazonia Inferred from Pollen at Lagoa do Caçó, Northern Brazil

2001 ◽  
Vol 55 (1) ◽  
pp. 47-56 ◽  
Author(s):  
Marie-Pierre Ledru ◽  
Renato Campello Cordeiro ◽  
José Maria Landim Dominguez ◽  
Louis Martin ◽  
Philippe Mourguiart ◽  
...  
Keyword(s):  
Amazon Basin ◽  
Ice Core ◽  
Late Glacial ◽  
Climatic Conditions ◽  
Convective Precipitation ◽  
Pollen Data ◽  
Moisture Source ◽  
Northern Latitudes ◽  
Low Latitudes ◽  
Northern Brazil

AbstractNew pollen data from a core at Lagoa do Caçó, Maranhão state, Brazil (2°58′S 43°25′W; 120 m elevation), show higher frequencies of Podocarpus at the end of the Pleistocene than today. The increase in Podocarpus, which follows the successive increase of various pioneer species such as Didymopanax, Melastomataceae/Combretaceae, and Cecropia, implies a progressive late-glacial increase of moist and cool climatic conditions. A comparable increase in Podocarpus is found in other lowland records in Amazonia. A review of published pollen data from Amazonia suggests that the moisture source was from the southeast. By contrast, present-day moisture comes from the tropical Atlantic and from the Amazon basin, with its convective precipitation. The likely cause for the southeastern moisture source between ca. 15,000 and 14,500 cal yr B.P. was enhanced polar (Antarctic) advection that reached low latitudes and maintained year-round the meteorological equator in its austral-winter position at northern latitudes or reduced drastically its southward summer displacement. This hypothesis is consistent with marine and ice core records.

scholarly journals Ocean carbon inventory under warmer climate conditions – the case of the Last Interglacial

2018 ◽  
Vol 14 (12) ◽  
pp. 1961-1976 ◽  
Author(s):  
Augustin Kessler ◽  
Eirik Vinje Galaasen ◽  
Ulysses Silas Ninnemann ◽  
Jerry Tjiputra
Keyword(s):  
Dissolved Inorganic Carbon ◽  
Carbon Sources ◽  
Climatic Conditions ◽  
Interglacial Period ◽  
Quasi Equilibrium ◽  
Biological Pump ◽  
Last Interglacial ◽  
Climate Conditions ◽  
Ocean Carbon ◽  
Carbon Inventory

Abstract. During the Last Interglacial period (LIG), the transition from 125 to 115 ka provides a case study for assessing the response of the carbon system to different levels of high-latitude warmth. Elucidating the mechanisms responsible for interglacial changes in the ocean carbon inventory provides constraints on natural carbon sources and sinks and their climate sensitivity, which are essential for assessing potential future changes. However, the mechanisms leading to modifications of the ocean's carbon budget during this period remain poorly documented and not well understood. Using a state-of-the-art Earth system model, we analyze the changes in oceanic carbon dynamics by comparing two quasi-equilibrium states: the early, warm Eemian (125 ka) versus the cooler, late Eemian (115 ka). We find considerably reduced ocean dissolved inorganic carbon (DIC; −314.1 PgC) storage in the warm climate state at 125 ka as compared to 115 ka, mainly attributed to changes in the biological pump and ocean DIC disequilibrium components. The biological pump is mainly driven by changes in interior ocean ventilation timescales, but the processes controlling the changes in ocean DIC disequilibrium remain difficult to assess and seem more regionally affected. While the Atlantic bottom-water disequilibrium is affected by the organization of sea-ice-induced southern-sourced water (SSW) and northern-sourced water (NSW), the upper-layer changes remain unexplained. Due to its large size, the Pacific accounts for the largest DIC loss, approximately 57 % of the global decrease. This is largely associated with better ventilation of the interior Pacific water mass. However, the largest simulated DIC differences per unit volume are found in the SSWs of the Atlantic. Our study shows that the deep-water geometry and ventilation in the South Atlantic are altered between the two climate states where warmer climatic conditions cause SSWs to retreat southward and NSWs to extent further south. This process is mainly responsible for the simulated DIC reduction by restricting the extent of DIC-rich SSW, thereby reducing the storage of biological remineralized carbon at depth.

scholarly journals How dry was the Younger Dryas? Evidence from a coupled <i>δ</i><sup>2</sup>H–<i>δ</i><sup>18</sup>O biomarker paleohygrometer applied to the Gemündener Maar sediments, Western Eifel, Germany

2019 ◽  
Vol 15 (2) ◽  
pp. 713-733 ◽  
Author(s):  
Johannes Hepp ◽  
Lorenz Wüthrich ◽  
Tobias Bromm ◽  
Marcel Bliedtner ◽  
Imke Kathrin Schäfer ◽  
...  
Keyword(s):  
Isotope Composition ◽  
Younger Dryas ◽  
Late Glacial ◽  
Climatic Conditions ◽  
Leaf Water ◽  
Early Holocene ◽  
Unexpected Finding ◽  
Temperature Dependent ◽  
The Past ◽  
Natural Climate

Abstract. Causes of the Late Glacial to Early Holocene transition phase and particularly the Younger Dryas period, i.e. the major last cold spell in central Europe during the Late Glacial, are considered to be keys for understanding rapid natural climate change in the past. The sediments from maar lakes in the Eifel, Germany, have turned out to be valuable archives for recording such paleoenvironmental changes. For this study, we investigated a Late Glacial to Early Holocene sediment core that was retrieved from the Gemündener Maar in the Western Eifel, Germany. We analysed the hydrogen (δ2H) and oxygen (δ18O) stable isotope composition of leaf-wax-derived lipid biomarkers (n-alkanes C27 and C29) and a hemicellulose-derived sugar biomarker (arabinose), respectively. Both δ2Hn-alkane and δ18Osugar are suggested to reflect mainly leaf water of vegetation growing in the catchment of the Gemündener Maar. Leaf water reflects δ2H and δ18O of precipitation (primarily temperature-dependent) modified by evapotranspirative enrichment of leaf water due to transpiration. Based on the notion that the evapotranspirative enrichment depends primarily on relative humidity (RH), we apply a previously introduced “coupled δ2Hn-alkane–δ18Osugar paleohygrometer approach” to reconstruct the deuterium excess of leaf water and in turn Late Glacial–Early Holocene RH changes from our Gemündener Maar record. Our results do not provide evidence for overall markedly dry climatic conditions having prevailed during the Younger Dryas. Rather, a two-phasing of the Younger Dryas is supported, with moderate wet conditions at the Allerød level during the first half and drier conditions during the second half of the Younger Dryas. Moreover, our results suggest that the amplitude of RH changes during the Early Holocene was more pronounced than during the Younger Dryas. This included the occurrence of a “Preboreal Humid Phase”. One possible explanation for this unexpected finding could be that solar activity is a hitherto underestimated driver of central European RH changes in the past.

scholarly journals The Recent Nature of the Siberian Pole of Cold

1961 ◽  
Vol 3 (30) ◽  
pp. 1089-1096
Author(s):  
I. P. Gerasimov
Keyword(s):  
Late Glacial ◽  
Climatic Conditions ◽  
Point Of View ◽  
Natural Conditions ◽  
Dominant Type ◽  
North East ◽  
Natural Landscapes ◽  
Mountain System ◽  
Soil Temperatures ◽  
Extreme North

Abstract The Siberian pole of cold is situated in the extreme north-east of Eurasia (in the region of the Cherskiy mountain system, in the upper parts of the basins of the Yana, Indigirka and Kolyma Rivers). Particularly low air and soil temperatures have been observed in the intermontane areas. Among these localities is the famous Oymyakon, where the lowest minimum temperature in the Northern Hemisphere has been recorded. In the climate of this area extreme aridity, connected with the intracontinental position of the territory, is combined with intense cold. In the two highest massifs (Ulakhan-Chistay and Suntar-Khayata) small centres of recent glacierization (chiefly kars) are developed; there are also distinct traces of a more extensive older mountain glaciation. In the intermontane areas and on the principal level of the dissected hilly peneplain positive indications of a former glaciation are absent. However, the recent cryogenic phenomena represented by fossil ice, permafrost, taryns, as well as thermokarstic, solifluction and congelation features, are very abundant and diverse. The widespread development of all these features gives this territory a periglacial aspect, and also provides the possibility of using the study of many recent phenomena for palaeogeographical purposes. From this point of view, the processes leading to the formation of loess deposits (cryogenic facies) and the formation of structural and thixotropic soils arc of particular interest. The recent natural landscapes in this region are represented by a dominant type of larch tundra–forest associated with comparatively typical taiga bog formations in the depressions and xero-cryophile meadow–steppe landscapes on the steeper and warmer southern slopes. Such a unique landscape combination connected with the specific climatic conditions of this region provide a basis for interpreting the recent natural conditions of the Siberian pole of cold as a survival of the “late glacial.” At present these natural conditions are being intensively developed economically.

Sedimentary and Paleoclimatic Controls on Caddisfly (Insecta: Trichoptera) Assemblages during the Last Interglacial-to-Glacial Transition in Southern Ontario

1995 ◽  
Vol 43 (1) ◽  
pp. 90-105 ◽  
Author(s):  
Nancy E. Williams ◽  
Nicholas Eyles
Keyword(s):  
Species Richness ◽  
Sedimentary Facies ◽  
Weather Conditions ◽  
Climatic Conditions ◽  
Last Interglacial ◽  
Fair Weather ◽  
Southern Ontario ◽  
Valley Site ◽  
Climatic Cooling ◽  
Temperate River

AbstractSouthern Ontario, Canada, has late Pleistocene deposits that contain evidence for climatic cooling during the last interglacial/glacial transition and much of the succeeding Wisconsin glaciation. Fossils of lacustrine and riverine caddisflies (Insecta: Trichoptera) are abundant and well-preserved in these deposits. We examined 26 samples from the interglacial section exposed in the Don Valley Brickyard and compared their caddisfly assemblages with those recovered from the overlying early Wisconsin Scarborough Formation deposits at nearby Scarborough Bluffs. Fifty-one caddisfly taxa in 16 families were recovered from the Don Valley site. Fossil abundance and species richness appear related to the storm or fair-weather conditions inferred from the sedimentary facies. Caddisfly fossils were most abundant and species richness highest in fair-weather, peaty, rippled sands. Highest proportions of river species as opposed to lake species were recovered from sands (storm and fair-weather). Assemblages from both sites indicate the presence of a large and productive river flowing into ancestral Lake Ontario. However, the river assemblage appeared to be far more sensitive to environmental change than the relatively stable assemblage representing the thermally buffered lake. Warm temperate river species such as Hydropsyche bidens, Hydropsyche mississippiensis, Macrostemum carolina, and Potamyia flava are present in the lower Don samples but absent from the Scarborough Bluffs deposits, while indicators of cooler than present climatic conditions such as Arctopsyche Indogensis and Hagenella canadensis are present in the Scarborough Bluffs sediments but absent from the lower Don samples. For the interval from about 80,000 to 55,000 yr B.P., we infer a climatic cooling from temperature about 2°C warmer than present to about 3°C cooler than present.

scholarly journals A new high-resolution pollen sequence at Lake Van, Turkey: insights into penultimate interglacial–glacial climate change on vegetation history

2017 ◽  
Vol 13 (6) ◽  
pp. 689-710 ◽  
Author(s):  
Nadine Pickarski ◽  
Thomas Litt
Keyword(s):  
High Resolution ◽  
Climate Variability ◽  
Eastern Mediterranean Region ◽  
Climatic Conditions ◽  
Semiarid Region ◽  
The Black Sea ◽  
Pollen Record ◽  
Lake Van ◽  
Last Interglacial ◽  
Pollen Records

Abstract. A new detailed pollen and oxygen isotope record of the penultimate interglacial–glacial cycle, corresponding to the marine isotope stage (MIS) 7–6, has been generated from the Ahlat Ridge (AR) sediment core at Lake Van, Turkey. The presented Lake Van pollen record (ca. 250.2–128.8 ka) displays the highest temporal resolution in this region with a mean sampling interval of  ∼  540 years.The integration of all available proxies shows three temperate intervals of high effective soil moisture availability. This is evidenced by the predominance of steppe-forested landscapes (oak steppe-forest) similar to the present interglacial vegetation in this sensitive semiarid region between the Black Sea, the Caspian Sea, and the Mediterranean Sea.The wettest and warmest stage, as indicated by highest temperate tree percentages, can be broadly correlated with MIS 7c, while the amplitude of the tree population maximum during the oldest penultimate interglacial (MIS 7e) appears to be reduced due to warm but drier climatic conditions. The detailed comparison of the penultimate interglacial complex (MIS 7) to the last interglacial (Eemian, MIS 5e) and the current interglacial (Holocene, MIS 1) provides a vivid illustration of possible differences in the successive climatic cycles. Intervening periods of treeless vegetation can be correlated with MIS 7d and 7a, in which open landscapes favor local erosion and detrital sedimentation. The predominance of steppe elements (e.g., Artemisia, Chenopodiaceae) during MIS 7d indicates very dry and cold climatic conditions. In contrast, the occurrence of higher temperate tree percentages (mainly deciduous Quercus) throughout MIS 7b points to relatively humid and mild conditions, which is in agreement with other pollen sequences in southern Europe.Despite the general dominance of dry and cold desert-steppe vegetation during the penultimate glacial (broadly equivalent to MIS 6), this period can be divided into two parts: an early stage (ca. 193–157 ka) with higher oscillations in tree percentages and a later stage (ca. 157–131 ka) with lower tree percentages and subdued oscillations. This subdivision of the penultimate glacial is also seen in other pollen records from southern Europe (e.g., MD01-2444 and I-284; Margari et al., 2010; Roucoux et al., 2011). The occurring vegetation pattern is analogous to the division of MIS 3 and MIS 2 during the last glacial in the same sediment sequence. Furthermore, we are able to identify the MIS 6e event (ca. 179–159 ka) as described in marine pollen records, which reveals clear climate variability due to rapid alternation in the vegetation cover.In comparison with long European pollen archives, speleothem isotope records from the Near East, and global climate parameters (e.g., insolation, atmospheric CO2 content), the new high-resolution Lake Van record presents an improved insight into regional vegetation dynamics and climate variability in the eastern Mediterranean region.

scholarly journals The Recent Nature of the Siberian Pole of Cold

1961 ◽  
Vol 3 (30) ◽  
pp. 1089-1096
Author(s):  
I. P. Gerasimov
Keyword(s):  
Late Glacial ◽  
Climatic Conditions ◽  
Point Of View ◽  
Natural Conditions ◽  
Dominant Type ◽  
North East ◽  
Natural Landscapes ◽  
Mountain System ◽  
Soil Temperatures ◽  
Extreme North

AbstractThe Siberian pole of cold is situated in the extreme north-east of Eurasia (in the region of the Cherskiy mountain system, in the upper parts of the basins of the Yana, Indigirka and Kolyma Rivers). Particularly low air and soil temperatures have been observed in the intermontane areas. Among these localities is the famous Oymyakon, where the lowest minimum temperature in the Northern Hemisphere has been recorded. In the climate of this area extreme aridity, connected with the intracontinental position of the territory, is combined with intense cold.In the two highest massifs (Ulakhan-Chistay and Suntar-Khayata) small centres of recent glacierization (chiefly kars) are developed; there are also distinct traces of a more extensive older mountain glaciation. In the intermontane areas and on the principal level of the dissected hilly peneplain positive indications of a former glaciation are absent. However, the recent cryogenic phenomena represented by fossil ice, permafrost, taryns, as well as thermokarstic, solifluction and congelation features, are very abundant and diverse.The widespread development of all these features gives this territory a periglacial aspect, and also provides the possibility of using the study of many recent phenomena for palaeogeographical purposes. From this point of view, the processes leading to the formation of loess deposits (cryogenic facies) and the formation of structural and thixotropic soils arc of particular interest.The recent natural landscapes in this region are represented by a dominant type of larch tundra–forest associated with comparatively typical taiga bog formations in the depressions and xero-cryophile meadow–steppe landscapes on the steeper and warmer southern slopes. Such a unique landscape combination connected with the specific climatic conditions of this region provide a basis for interpreting the recent natural conditions of the Siberian pole of cold as a survival of the “late glacial.” At present these natural conditions are being intensively developed economically.

Regional Variability in Lithic Miniaturization and the Organization of Technology in Late Glacial Southern Africa (~18-11 kcal BP)

2020 ◽  
Vol 18 (1) ◽  
pp. 38-66 ◽  
Author(s):  
Marika Low ◽  
Justin Pargeter
Keyword(s):  
Southern Africa ◽  
Raw Materials ◽  
Late Glacial ◽  
Regional Variability ◽  
Local Conditions ◽  
Lithic Assemblages ◽  
Lithic Reduction ◽  
Organization Of Technology ◽  
Controlled Fracture ◽  
Technological Study

Abstract Miniaturized stone tools made by controlled fracture are reported from nearly every continent where archaeologists have systematically looked for them. While similarities in technology are acknowledged between regions, few detailed inter-regional comparative studies have been conducted. Our paper addresses this gap, presenting results of a comparative lithic technological study between Klipfonteinrand and Sehonghong – two large rock shelters in southern Africa. Both sites contain Late Glacial (~18-11 kcal BP) lithic assemblages, though they are located in regions with different geologies, climates and environments. Results demonstrate that lithic miniaturization manifests differently in these different regions. Both assemblages provide evidence for small blade production, though key differences exist in terms of the specific technological composition of this evidence, the raw materials selected, the role played by bipolar reduction and the manner in which lithic reduction was organized. Patterned variability of this nature demonstrates that humans deployed miniaturized technologies strategically in relation to local conditions.

scholarly journals The Late Glacial and Holocene development of vegetation in the area of a fossil lake in the Skaliska Basin (north-eastern Poland) inferred from pollen analysis and radiocarbon dating

2013 ◽  
Vol 53 (1) ◽  
pp. 23-52 ◽  
Author(s):  
Piotr Kołaczek ◽  
Mirosława Kupryjanowicz ◽  
Monika Karpińska-Kołaczek ◽  
Marta Szal ◽  
Hanna Winter ◽  
...  
Keyword(s):  
Picea Abies ◽  
Radiocarbon Dating ◽  
Late Phase ◽  
Late Glacial ◽  
Corylus Avellana ◽  
Rapid Expansion ◽  
Vegetation Development ◽  
Modern Times ◽  
North Eastern ◽  
Late Glacial And Holocene

ABSTRACT The development of vegetation in the Skaliska Basin has been reconstructed on the basis of palynological analysis and radiocarbon dating (AMS technique) of 6 sites from the late phase of the Bolling- Allerod interstadial complex to modern times. Although the area covers 90 km2, the mosaic character of habitats led to the development of different patterns of vegetation changes during the Late Glacial and Holocene. Only one site located in the eastern part of the Skaliska Basin reflected the ‘pine phase’ of Allerod, and this is the oldest data on vegetation in the Skaliska Basin. Interesting discrepancies were recorded during the Younger Dryas when patches of shrublands with Juniperus were distinct around some of the sites, while steppe with Artemisia was common in others. The beginning of the Holocene brought an expansion of birch-pine forest, but around 9600 cal. BC a cold oscillation took place which was reflected in an increase in birch in the woodlands in the western and eastern part of the Skaliska Basin. In the Preboreal chronozone elm (Ulmus) also expanded in the area but its appearance was non-synchronous. The vegetation of the Boreal chronozone was similar in the whole area and the most characteristic feature was the rapid expansion of hazel (Corylus avellana) which displaced Betula from the most of its sites. At that time a distinct redeposition of pollen material in the Parchatka river valley was detected which was probably the effect of an increase in fluvial activity of the river (humid oscillation). The following stage of vegetation development was climax woodlands with Tilia cordata, Ulmus, Quercus, Corylus avellana, and Alnus in damp places. At the beginning of the Subboreal chronozone the expansion of Quercus took place, which was subsequently replaced by Picea abies and partly Carpinus betulus. The pattern of Picea abies expansion distinctly presents two maxima which is characteristic of many sites in the north-eastern Poland. The Subatlantic chronozone is represented only by the profile from the Skaliski Forest, where, because of sandy ground, Pinus sylvestris was the dominant element. Human impact was poorly reflected through the rare occurrence of pollen grains of Cerealia type in the pollen profiles spanning the time from the Subboreal chronozone to modern times. In most profiles AMS dating produced age discrepancies, which limited the possibility of establishment of a detailed chronology. However, dates obtained from the material contaminated by mixture of glycerine, thymol and ethyl alcohol, pretreated by alcohol, showed reliable results in most cases.

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