inscription
PORTAIL D'INFORMATION GÉOGRAPHIQUE

Résultats de la recherche (133 résultats)

Affinez votre recherche

Par Collection Par Auteur Par Date Par Sujet Par Titre
  • Tephra in 31 piston cores from the western Gulf of Mexico and 7 piston cores from the equatorial Pacific were analyzed by electron microprobe.
  • Bilan thermique ; Brouillard ; Centre-périphérie ; Centre-ville ; Climat local ; Climat urbain ; Climatologie ; Géographie physique ; Helsinki ; Nice ; Paris ; Pluie ; Pollution ; Précipitation ; Radiation ; Radiation solaire ; Saint-Nazaire
  • Cet article présente trois problèmes posés par la climatologie urbaine: augmentation des précipitations dans les villes, modification des rapports énergétiques entre la ville et sa périphérie, urbanisation et pollution.
  • The presence of the Brunhes-Matuyama magnetic reversal in deep-sea core sediments makes possible an alternative to the usual K/Ar radioisotope method of dating the reversal as found in rocks. The alternative method uses correlations of Northern
  • Hemisphere summer insolation with oxygen-isotope ratios from tropical cores. The latitude-dependent insolation variations are calculated from planetary mechanics and thus provide a highly accurate astronomical time scale. The insolation variations strongly
  • influence glacial-ice volume fluctuations that dominate the oxygenisotope ratio changes recorded in core sediments. The summer half-year insolation variations are identified with corresponding isotope-ratio changes in cores from the present through glacial
  • isotope-ratio minima in the two cores (relative to ages based on uniform overall deposition) to match the ages of low-eccentricity insolation minima. The age shifts reflect residual nonuniformities of deposition. The validity of this matching procedure
  • Sequence of sediments at Locality 1 in Zhoukoudian and correlation with loess stratigraphy in northern China and with the chronology of deep-sea cores
  • -L4) in China and with deep-sea-core oxygen-isotope stages 16-6. The 14th layer upward (730,000-230,000 yr B.P.) represents at least four glacial cycles.
  • High resolution isotope study of the latest deglaciation based on Bermuda Rise cores
  • A stable isotope and C investigation of carbonates from three late Quaternary cores with high rates of sedimentation from the northeastern Bermuda Rise has produced the highest resolution record of the glacial maximum to Holocene stable isotope
  • A Younger Dryas ash bed in western Norway, and its possible correlations with tephra in cores from the Norwegian Sea and the North Atlantic
  • having a bimodal basaltic and rhyolitic composition. The geochemistry of the glass shards suggests an Icelandic source. By means of stratigraphic position and geochemistry, the ash is correlated with ash zones found in cores from the continental shelf
  • Comparisons of sedimentation rates obtained by Pb and pollen analyses of 1-m cores collected throughout the Potomac Estuary show good agreement in the majority of cores that can be analyzed by both methods. Most of the discrepancy between
  • the methods can be explained by the analytical precision of the Pb method and by the exactness with which time horizons can be identified and dated for the pollen method. X-radiographs of the cores and the distinctness of the pollen horizons preclude
  • Five widespread tephra layers are found in late Quaternary sediments (0130,000yr B.P.) of the Eastern Mediterranean Sea. These layers have been correlated among abyssal cores and to their respective terrestrial sources by electron-probe
  • microanalysis of glass and pumice shards. Major element variations are sufficient to discriminate unambiguously between the five major layers. Oxygen isotope stratigraphy in one of the cores studied was used to data four of the five layers. Two of the widespread
  • layers are derived from explosive eruptions of the Santorini volcanic complex: the Minoan Ash (3370yr B.P.) and the Acrotiri Ignimbrite (18,000yr B.P.). An additional layer, found in one core only, is most likely correlated to the Middle Pumice Series
  • LATE PLEISTOCENE PALEOCLIMATOLOGY: PLANKTONIC FORAMINIFERAL ANALYSES OF SEDIMENT CORES FROM THE CENTRAL NORTH ATLANTIC
  • Chemical composition of ice containing tephra layers in the Byrd Station ice core, Antarctica
  • Rates of sediment accumulation in pollen cores from small lakes and mires of eastern North America
  • In this paper, the stable isotopic stratigraphies of two size fractions (>38 and
  • Revised magnetostratigraphies confirm low sedimentation rates in Artic Ocean Cores
  • Past Antarctic Peninsula climate (1850-1980) deduced from an ice core isotope record
  • Geomorphology of metamorphic core complex mountains in Arizona and S. E. California
  • Magnetic, palynological and radiocarbon correlation and dating comparisons in long cores from a northern irish lake
  • Carbonate content and faunal composition of two gravity cores from the coastal Arabian sea provide evidence of a major environmental change in surface ocean waters about 13,000 yr B.P. Radiocarbon dating indicates that deposition rates ranged from
  • 1.8 to 9.8 cm/10 yr, with a major change in rate occurring in one core at about 7500 yr B.P.
  • Palaeo-climatic studies on ice cores in Climatic variations and variability: facts and theories.
  • Postglacial paleogeography in the Tokoro and Sarobetsu lowlarids, Hokkaido, is discussed based on facies and fossil analyses of undisturbed boring cores.
  • Analytical study by X Ray diffrection and Scanning Microscope of highly weathered prehistoric flints. Thanks to ressembling of debitage products, differently weathered though they are coming from the same core, it is proved that a part of the silica