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PORTAIL D'INFORMATION GÉOGRAPHIQUE

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  • A technique of alluviation rate estimation has been developed as a result of archaelogical and geomorphological studies carried out at archaelogical sites at the middle Oka floodplain dated from Early Neolithic to the Middle Ages. The technique
  • 1981
  • Age subactuel des dernières manifestations éruptives du Mont Dore et du Cézallier
  • 1981
  • Palaeoclimatology before our ice age in Climatic variations and variability: facts and theories.
  • 1981
  • The formation and age of ice in caves
  • 1981
  • Origin, age and movement of pore water in argilleous Quaternary deposits at four sites in southwestern Ontario
  • 1981
  • Obsidian hydration dating of volcanic events had been compared with ages of the same events determined by the C and K-Ar methods at several localities ranging in age from 1200 to over 1million yr. In most cases the agreement is quite good. A number
  • of factors including volcanic glass composition and exposure-temperature history must be known in order to relate hydration thickness to age. The effect of composition can be determined from chemical analysis or the refractive index of the glass. Exposure
  • 1981
  • A linear regression between lens weight and age was found in 24 dormice aged 1.5 to 6.0 months. The estimaded value of the lens weight was given by the following equation Y = 27, 448 X + 70, 801. The upper and lower limits of the confidence
  • intervals were calculated. The age of 41 wild dormice was estimated by the inverse prediction method of Sokal and Rohlf (1969). The estimated age thus established was in agreement with estimates based on other morphological and behavioural criteria
  • 1981
  • The correspondence analysis method has been used to ordinate a sample of 88 wild garden dormice in four age groups. The first three groups include animals which have not yet passed through their first, second and third hibernation periods
  • respectively. The last group corresponds to individuals which have hibernated more than three times. The body weight of the garden dormice, together with the condylobasal lenght and bizygomatic width of their skulls, are good indicators of age.
  • 1981
  • Three radiometric methods have been used to date Quaternary tephra: fission-track (F-T), K-Ar, and radiocarbon (C-14). The fission-track and K-Ar methods provide direct ages for the tephra because they date phenocrysts from the source magma
  • that were deposited by the eruption cloud. Radiocarbon dating provides only indirect ages because the carbon used in this method comes from material, such as pre-existing wood, included in the tephra during deposition or collected from underlying
  • 1981
  • south of Kilifi. Unfortunately, there are few indications for the age of the shore elements levels. However, there are some indications of a rather recent age (below about 3000 years) for the lower levels below c. 10-11 m above Datum.
  • 1981
  • The SW decrease in age of the South American pre-Andean orogenies suggests a revision of the relative positions of South America and West Antarctica within Gondwana.
  • 1981
  • influence the activity rythm and differences between age classes are discussed.
  • 1981
  • The age relationships between Rogen moraine ridges in the Central swedish mountains and subglacially engorged valley side eskers on the mountain slopes are discussed. The movement rates of the downwasting ice remnants within the final ice-divide
  • 1981
  • Solar activity cannot be disregarded as a possible external cause of the Little Ice Age and the 20th century climatic warming. Climatic responses to the 11-and 22-year solar cycles, although relatively weak are in evidence. Further (case-) studies
  • 1981
  • Datation ; Datation radiocarbone ; Europe du Nord ; Glaciaire ; Glaciation ; Géographie physique ; Jotunheimen ; Lichenométrie ; Moraine ; Moraine terminale ; Norvège ; Paléosol ; Petit Age Glaciaire ; Scandinavie ; Tverrbreen ; Variation climatique
  • 1981
  • the last thousand years. Two levels with high concentrations of pumice have been dated by driftwood samples with ages of 5240 70 years and 3110 80 years. Driftwood seems to have floated ashore throughout most of the Holocene. The about 9000 years old
  • 1981
  • are results of the still lasting evolutionary process as to tectonics ans structure which started at the sedimentation in the Permian-Mesozoic age and is characterized by changing activities and intensities. (d'après HL).
  • 1981
  • Age 40Ar/39Ar: 179 7 MA. L'analyse géochimique des basaltes et des intrusions associées fournit des informations sur le manteau lithosphérique subcontinental. L'âge, la répartition et le volume des tholéiites renseignent indirectement sur les
  • 1981
  • blanket an early Holocene landscape. The sediments are of mid-Holocene age and were deposited during the interval 4500B.P. 3800yr B.P., when the southwesterly winds were stronger than they are at present and much of tropical Africa seems to have been
  • 1981
  • 4 000 ans. On décrit les traits caractéristiques de la structure temporelle des extêmes à différents intervalles de la période historique, en particulier à l'époque du petit optimum climatique du Moyen Age (X-XIII ss.). On montre l'utilité d'employer
  • 1981