Search results for "50"

Flore du Jurassique basal de la ville de Mende (Lozère) : synthèse des gisements historiques, nouvelles données sédimentologiques, paléontologiques e…

2019

Resume Au cours du XXe siecle, la majorite des sites a plantes fossiles (Hettangien–Sinemurien) de la ville de Mende ont disparu a cause d’une importante urbanisation ou bien sont tombes dans l’oubli. Cet article presente une synthese des gisements a vegetaux fossiles, depuis leur decouverte au XIXe siecle jusqu’aux campagnes de prospection recentes. De nouvelles donnees lithostratigraphiques et paleobotaniques sont apportees pour deux sites historiques (le Ravin del Pouset et le Petit Seminaire), ainsi que deux localites fossiliferes dernierement decouvertes (route du Causse-d’Auge et route de Gardes). Cette etude revele la diversite des lithofacies contenant les plantes (dolomudstone, mar…

La radiation des échinodermes au Paléozoïque inférieur, l'exemple des blastozoaires.

2009

10 pages; Le sous-phylum Blastozoa est un des groupes d'échinodermes les plus diversifiés (dix classes) au début du Paléozoïque. Après révision critique de leur squelette, leurs morphologies en apparence très variées sont en fait homogènes. Leur diversité montre deux pics (Drumien, Sandbien) liés par un événement de fortes apparitions génériques au Cambrien supérieur-Ordovicien inférieur. Les blastozoaires montrent un fort endémisme au Cambrien et un important provincialisme à l'Ordovicien inférieur et moyen. Ils deviennent cosmopolites à l'Ordovicien supérieur, par plusieurs événements migratoires. Ils sont restreints à la Laurentia et à Baltica au Silurien inférieur.

Rhinocerotid tooth enamel 18O/16O variability between 23 and 12 Ma in southwestern France.

2006

Abstract The relationship between the oxygen isotope ratio of mammal tooth enamel and that of drinking water was used to reconstruct changes in the Miocene oxygen isotope ratio of rainfall (meteoric water δ 18 O MW ). These, in turn, are related to climatic parameters (temperature, precipitation and evaporation rate). δ 18 O values of rhinocerotid teeth from the Aquitaine Basin (southwestern France) suggest a significant climatic change between 17 and 12 Ma, characterized by cooling together with precipitation increase, in agreement with other terrestrial and oceanic records. To cite this article: I. Bentaleb et al., C. R. Geoscience 338 (2006).

The Use of Medicinal Clay from Silesia “Terra sigillata Silesiaca”, Central Europe - A New Chance for Natural Medicine?

2019

Silesia is a region in Central Europe with beneficial conditions for the presence of clay, including those with potential therapeutic efficacies, due to its very diverse and mosaic geological landscape. The first use of clay deposits in medicine in Silesia, “terra sigillata Silesiaca”, has been dated to 1550 AD, and the oldest written information related to this use has been dated to 1586 AD. Medicinal clay is formed by the accumulation of a mixture of minerals such as smectite, bentonite, montmorillonite, kaolinite, illite, and metahaloisite, with impurities of other minerals and fractions, resulting from the chemical weathering of rocks and the sedimentation of detritus. The quantitative …

The Late Ordovician glacial sedimentary system of the North Gondwana platform.

2009

International audience; The Late Ordovician (Hirnantian) glaciation is examined through the North Gondwana record. This domain extended from southern high palaeo-latitudes (southeastern Mauritania, Niger) to northern lower palaeo-latitudes (Morocco, Turkey) and covered a more than 4000 km-wide section perpendicular to ice-flow lines. A major mid-Hirnantian deglaciation event subdividing the Hirnantian glaciation in two first-order cycles is recognised. As best illustrated by the glacial record in western Libya, each cycle comprises 2-3 glacial phases separated by ice-front retreats several hundreds kilometres to the south. From ice-proximal to ice-distal regions, the number of glacial surfa…

Five centuries of Central European temperature extremes reconstructed from tree-ring density and documentary evidence

2010

Future climate change will likely influence the frequency and intensity of weather extremes. As such events are by definition rare, long records are required to understand their characteristics, drivers, and consequences on ecology and society. Herein we provide a unique perspective on regional-scale temperature extremes over the past millennium, using three tree-ring maximum latewood density (MXD) chronologies from higher elevations in the European Alps. We verify the tree-ring-based extremes using documentary evidences from Switzerland, the Czech Republic, and Central Europe that allowed the identification of 44 summer extremes over the 1550-2003 period. These events include cold temperat…

Experimental socioecology: Integrative science for anthropocene landscape dynamics

2016

Abstract The emergence of coupled natural and human landscapes marked a transformative interval in the human past that set our species on the road to the urbanized, industrial world in which we live. This emergence enabled technologies and social institutions responsible for human-natural couplings in domains beyond rural, agricultural settings. The Mediterranean Landscape Dynamics Project (MedLand) is studying the interacting social and biophysical processes associated with these novel socioecological systems and their long-term consequences using a new form of 'experimental socioecology' made possible by recent advances in computation. We briefly describe the MedLand modeling laboratory, …

The ELSA-Flood-Stack: A reconstruction from the laminated sediments of Eifel maar structures during the last 60 000 years

2016

Abstract This study reconstructs the main flood phases in central Europe from event layers in sediment cores from Holocene Eifel maar lakes and Pleistocene dry maar structures. These reconstructions are combined with recent gauge time-series to cover the entire precipitation extremes of the last 60 000 years. In general, Eifel maar sediments are perfectly suited for the preservation of event layers since the deep water in the maar lakes is seasonal anoxic and therefore, bioturbation is low. However, the preservation of annual lamination is only preserved in Holzmaar and Ulmener Maar; the other cores are dated by 14C, magnetostratigraphy, tephra markers and ice core tuning. The cores were dr…

The ELSA - Stacks (Eifel-Laminated-Sediment-Archive): An introduction

2016

Climate indices in historical climate reconstructions: a global state of the art

2021

Narrative evidence contained within historical documents and inscriptions provides an important record of climate variability for periods prior to the onset of systematic meteorological data collection. A common approach used by historical climatologists to convert such qualitative information into continuous quantitative proxy data is through the generation of ordinal-scale climate indices. There is, however, considerable variability in the types of phenomena reconstructed using an index approach and the practice of index development in different parts of the world. This review, written by members of the PAGES (Past Global Changes) CRIAS working group – a collective of climate historians a…