The Pollen Sequence of Les Échets (France): A New Element for the Chronology of the Upper Pleistocene

Les Échets mire (near Lyon, France) is one of the very few European sites showing an almost continuous record from the glaciation that preceded the Eemian up to now. The pollen diagram can easily be correlated with those from Grande Pile (Vosges). On the basis of a comparison between the two sequences, the age of three clearly temperate post-Eemian episodes (Saint-Germain Ia, Ic and Il at Grande Pile) is discussed. The authors correlate these episodes with the Early Würm Interstadials of Amersfoort, Brorup and Odderade described in Northern Europe and accept the chronology of Grande Pile that dates Saint-Germain I and Saint-Germain Il between ca 115 000 and 70 000 BP, thus making them equivalents of deep sea isotopic stages 5c and 5a. This leads to refute the 14C chronology admitted up to now that places the Early Würm between 75 000 and 55 000 BP. Considering the predominant temperate episodes during this period, the authors propose to use the term "Pre-Würm" instead of "Early Würm". During the Middle Würm, three not well-marked interstadials can be recognized. No interstadial is found during the late Pleni-Würm.Le marais des Échets (près de Lyon, France) constitue l'un des rares sites européens qui présente un remplissage à peu près continu depuis la glaciation qui a précédé l'Éémien jusqu'à nos jours. Le diagramme pollinique peut aisément être mis en corrélation avec ceux de La Grande Pile (Vosges). À partir de comparaisons entre ces deux séquences, la position chronostratigraphique des trois épisodes très nettement tempérés post-éémiens (Saint-Germain la, Ic et II à La Grande Pile) est discutée. Les auteurs mettent en corrélation ces épisodes avec les interstades du Würm ancien, Amersfoort, Brorup et Odderade, décrits en Europe du Nord et acceptent la chronologie de La Grande Pile qui situe Saint-Germain I et II entre environ 115 000 et 70 000 BP et qui en font les équivalents des étages isotopiques océaniques 5c et 5a. Ceci implique que la chronologie 14C admise jusqu'ici et plaçant le Würm ancien entre environ 75 000 et 55 000 BP est totalement erronée. Compte tenu de la prépondérance des épisodes tempérés durant cette période, les auteurs proposent le remplacement de la dénomination "Würm ancien" par celle de "Pré-Würm ". Durant le Würm moyen, trois interstades de faible amplitude ont été reconnus aux Échets, alors qu'aucune variation climatique positive n'est décelable durant le Pléni-Würm final.Das Moor von Les Échets (in der Nàhe von Lyon, Frankreich) ist eines der wenigen europàischen Gelànde, das ein fast kontinuierliches Zeugnis ablegt von der dem Eemian vorausgehenden Eiszeit bis heute. Das Pollendiagramm kann sehr leicht mit denen von Grande Pile (Vogesen) in Zusammenhang gebracht werden. Ausgehend von dem Vergleich zwischen diesen zwei Sequenzen wird das Alter von drei auf das Eemian folgenden und eindeutig gemàpigten Stadien diskutiert (Saint-Germain la, Ic und Il in Grande Pile). Die Autoren setzen dièse Episoden in Beziehung zu den Interstadialen von Amersfoort, Brerup und Odderade, die in Nord Europa beschrieben werden und akzeptieren die Chronologie von Grande Pile, die Saint-Germain I und Saint-Germain II zwischen etwa 115 000 und 70 000 v.u.Z. datiert, und sie so zu Àquivalenten der iso-topischen Tiefsee-Stadien 5c und 5a macht. Das fùhrt zu einer Ablehnung der 14C Chronologie, die bisher galt, und das frühe Würm zwischen 75 000 und 55 000 v.u.Z. ansetzte. Unter Beachtung der dominierenden gemàssigten Episoden wàhrend dieser Zeit schlagen die Autoren vor, den Terminus "Prâ-Würm" an Stelle von "Frùhes Würm" zu benutzen. Wàhrend des Mittel-Würms kônnen drei nicht gut voneinander abgegrenzte Interstadiaie erkannt werden. Während des spàteren Pleni-Würms kann kein Interstadial festgestellt werden

An oxygen isotope record of lacustrine opal from a European Maar indicates climatic stability during the Last Interglacial

The penultimate temperate period, 127–110 ka before present (BP), bracketed by abrupt shifts of the global climate system initiating and terminating it, is considered as an analogue of the Holocene because of a similar low global ice‐volume. Ice core records as well as continental and marine records exhibit conflicting evidence concerning the climate variability within this period, the Last Interglacial. We present, for the first time, a high‐resolution record of oxygen isotopes in diatom opal of the Last Interglacial obtained from the Ribains Maar in France (44°50′09″N 3°49′16″E). Our results indicate that the Last Interglacial in southwestern Europe was generally a period of climatic stability. The record shows that the temperate period was initiated by an abrupt warm event followed midway by a minor climatic transition to a colder climate. An abrupt isotopic depletion that occurs simultaneously with abrupt changes in pollen and diatom assemblages marks the end of the temperate period, and is correlative with the Melisey I stadial. Variations in the isotopic composition of lake‐water related to the isotopic composition of precipitation and evaporation dominate the biogenic opal oxygen isotope record

Développer le pouvoir d’apprendre : pour une critique de la transmission en éducation et en formation

Researchers of the TAO Research Programs and the Centre de Recherche sur le Travail et le Développement (Research Center on Work and Development) at the Conservatoire National des Arts et Métiers, Paris, illustrate critical reflections on education and training. These collected papers, stemming from different disciplinary frameworks and approaches, share the theoretical work and the epistemological orientation. With particular reference to the teachings of Weber, Vygotskij and Bakhtin, they focus on learning, conceived as social action, on the development of learning activity, and on the development of thought in professional dialogues. Along this line, the idea according to which education and training realize the “transmission” of knowledge, capacity, competence, values, practices, gestures, etc., is questioned and discussed

Modern pollen rain–vegetation relationships along a forest–steppe transect in the Golestan National Park, NE Iran

Pollen rain-vegetation relationships were studied over a forest-steppe transect in Golestan National Park, NE Iran. The surface pollen percentages were compared to the vegetation composition of the respective vegetation types in 18 sampling points using both descriptive and numerical approaches. Hyrcanian lowland forests are characterized by pollen assemblages dominated by Quercus, Carpinus betulus and low frequencies of Zelkova carpinifolia. Both Parrotia persica and Zelkova carpinifolia show a very low pollen representation in modern surface samples, an under-representation that should be taken into account in the interpretation of past vegetation records. Transitional communities between the forest and steppe including Acer monspessulanum subsp. turcomanicum, Crataegus and Paliurus scrubs, Juniperus excelsa woodlands and shrub-steppe patches are more difficult to distinguish in pollen assemblages, however, they are characterized by higher values of the dominant shrub species. The transitional vegetation communities at the immediate vicinity of the forest show also a substantial amount of grass pollen. Many insect-pollinated taxa are strongly under-represented in the pollen rain including most of the rosaceous trees and shrubs, Rhamnus, Paliurus, Acer and Berberis. Artemisia steppes are characterized by very high values of Artemisia pollen and the near absence of tree pollen

Beauvoir for the Masses: Exploring Applications of Her Philosophy in French Social Revolutions of the 1960’s

My project examines the feminism and existentialism of Simone de Beauvoir as they intersect with the ideas of the French social movements of the1960’s, using the movement of May \u2768 as a primary example. Beauvoir\u27s ideas were politically in tune with the leftist philosophy of the students and workers who organized widespread demonstrations throughout the spring of 1968 and brought the French economy to a standstill in May of that year. But I argue that her existentialist philosophy, foregrounding the necessity of each individual to create a self and to reject accepted social paradigms, reflects the demands made by the students who wished to re-make the university and society. And, importantly, her conception of feminism – which grew from her existentialist ideas – explores the way in which the struggles of a singular person can represent those of an entire group, thus mirroring arguments of the Mouvement du 22 mars, with their emblematic phrase expressing their sense of oppression, Nous sommes tous des juifs allemands ( We are all German Jews. ). The importance of the May \u2768 movement and its intersection with Beauvoir\u27s ideas relative to feminism and philosophy point toward a greater understanding of the complexity of French identity

Sensibilité de la sédimentation organique aux variations climatiques du Tardi-Wuerm et de l'Holocène; le lac du Bouchet (Haute-Loire, France)

Deux carottes de sédiments superficiels (2 à 3 m) prélevées dans le lac du Bouchet (Haute Loire, France) ont été étudiées du point de vue de leur composition minérale et organique. Les corrélations établies à partir des données concernant lamatière organique ainsi que celles de la palynologie, ont permis de replacer les deux premiers mètres de la série sédimentaire dans la logique climato-stratigraphique du passage Tardi-Würm-Holocène. Nous montrons ici que des variations climatiques de faible amplitude comme celles de l'Holocène, engendrent des changements importants dans la nature, la quantité et le mode de préservation des constituants organiques sédimentés

Using palynology to re-assess the Dead Sea laminated sediments – indeed varves?

Lacustrine laminated sediments are often varves representing annual rhythmic deposition. The Dead Sea high-stand laminated sections consist of mm-scale alternating detrital and authigenic aragonite laminae. Previous studies assumed these laminae were varves deposited seasonally. However, this assumption has never been robustly validated. Here we report an examination of the seasonal deposition of detrital-aragonite couplets from two well-known Late Holocene laminated sections at the Ze’elim fan-delta using palynology and grain-size distribution analyses. These analyses are complemented by the study of contemporary flash-flood samples and multivariate statistical analysis. Because transport affects the pollen preservation state, well–preserved (mostly) air-borne transported pollen was analysed separately from badly-preserved pollen and fungal spores, which are more indicative of water transport and reworking from soils. Our results indicate that (i) both detrital and aragonite laminae were deposited during the rainy season; (ii) aragonite laminae have significantly lower reworked and fungal spore concentrations than detrital and flash-flood samples; and (iii) detrital laminae are composed of recycling of local and distal sources, with coarser particles that were initially deposited in the Dead Sea watershed and later transported via run-off to the lake. This is in line with previous carbon balance studies that showed that aragonite precipitation occurs after the massive input of TCO2 associated with run-off episodes. Consequently, at least for the Holocene Ze’elim Formation, laminated sediments cannot be considered as varves. Older Quaternary laminated sequences should be re-evaluated

A 12.5-kyr history of vegetation dynamics and mire development with evidence of Younger Dryas larch presence in the Verkhoyansk Mountains, East Siberia, Russia

A 415 cm thick permafrost peat section from the Verkhoyansk Mountains was radiocarbon-dated and studied using palaeobotanical and sedimentological approaches. Accumulation of organic-rich sediment commenced in a former oxbow lake, detached from a Dyanushka River meander during the Younger Dryas stadial, at ∼12.5 kyr BP. Pollen data indicate that larch trees, shrub alder and dwarf birch were abundant in the vegetation at that time. Local presence of larch during the Younger Dryas is documented by well-preserved and radiocarbon-dated needles and cones. The early Holocene pollen assemblages reveal high percentages of Artemisia pollen, suggesting the presence of steppe-like communities around the site, possibly in response to a relatively warm and dry climate ∼11.4–11.2 kyr BP. Both pollen and plant macrofossil data demonstrate that larch woods were common in the river valley. Remains of charcoal and pollen of Epilobium indicate fire events and mark a hiatus ∼11.0–8.7 kyr BP. Changes in peat properties, C31/C27 alkane ratios and radiocarbon dates suggest that two other hiatuses occurred ∼8.2–6.9 and ∼6.7–0.6 kyr BP. Prior to 0.6 kyr BP, a major fire destroyed the mire surface. The upper 60 cm of the studied section is composed of aeolian sands modified in the uppermost part by the modern soil formation. For the first time, local growth of larch during the Younger Dryas has been verified in the western foreland of the Verkhoyansk Mountains (∼170 km south of the Arctic Circle), thus increasing our understanding of the quick reforestation of northern Eurasia by the early Holocene

Post-disturbance vegetation dynamics during the Late Pleistocene and the Holocene: An example from NW Iberia

This is the post-print version of the final paper published in Global and Planetary Change. The published article is available from the link below. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. Copyright @ 2012 Elsevier B.V.There is a wealth of studies dealing with the reconstruction of past environmental changes and their effects on vegetation composition in NW Iberia, but none of them have focused specifically on the post-disturbance dynamics (i.e. the type of response) of the vegetation at different space and time scales. To fill this gap, we analysed the record of pollen and non-pollen palynomorphs (NPP) of a 235-cm thick colluvial sequence spanning the last ~ 13,900 years. The aims were to detect the changes in vegetation, identify the responsible drivers and determine the type of responses to disturbance. To extract this information we applied multivariate statistical techniques (constrained cluster analysis and principal components analysis on transposed matrices, PCAtr) to the local (hydro-hygrophytes and NPP) and regional (land pollen) datasets separately. In both cases the cluster analysis resulted in eight local and regional assemblage zones, while five (local types) and four (regional types) principal components were obtained by PCAtr to explain 94.1% and 96.6% of the total variance, respectively. The main drivers identified were climate change, grazing pressure, fire events and cultivation. The vegetation showed gradual, threshold and elastic responses to these drivers, at different space (local vs. regional) and time scales, revealing a complex ecological history. Regional responses to perturbations were sometimes delayed with respect to the local response. The results also showed an ecosystem resilience, such as the persistence of open Betula-dominated vegetation community for ~ 1700 years after the onset of the Holocene, and elastic responses, such as the oak woodland to the 8200 cal yr BP dry/cold event. Our results support the notion that palaeoecological research is a valuable tool to investigate ecosystem history, their responses to perturbations and their ability to buffer them. This knowledge is critical for modelling the impact of future environmental change and to help to manage the landscape more sustainably.The Spanish Governmen