inscription
PORTAIL D'INFORMATION GÉOGRAPHIQUE

Résultats de la recherche (126 résultats)

Affinez votre recherche

Par Collection Par Auteur Par Date Par Sujet Par Titre Par ville ? Par pays ? Par continent ?
  • Dust emission from wet and dry playas in the Mojave Desert, USA
  • California ; Domaine aride ; Désert ; Eau du sol ; Eolien ; Erosion éolienne ; Etats-Unis ; Evaporite ; Playa ; Poussière ; Sédimentologie
  • Aeolian features ; Arid area ; California ; Desert ; Dust ; Evaporite ; Playa ; Sedimentology ; Soil water ; United States of America ; Wind erosion
  • The aim of this paper is to show that different processes control fundamentally different amounts and compositions of dust emitted from 2 distinct types of playa : the wet and dry playas. Surface sediments at 3 wet playas (Lake playas) are dynamic
  • and at times are vulnerable to wind erosion and dust emission. Surface sediments at dry playas, on the other hand, are typically stable and hard and thus generally do not emit large amounts of dust when undisturbed by human activities. The emphasis
  • of this report is on the hydrologic and sedimentologic interactions that may sustain dust production from wet playas.
  • The role of playas in pedogenic gypsum crust formation in the central Namib Desert : a theoretical model
  • Aérosol ; Domaine aride ; Déflation éolienne ; Désert ; Encroûtement ; Gypse ; Namibie ; Playa ; Pédogenèse ; Sebkha
  • Aeolian deflation ; Aerosol ; Arid area ; Desert ; Duricrust ; Gypsum ; Namibia ; Pedogenesis ; Playa ; Sebkha
  • The formation of Namibia's extensive pedogenic gypsum crusts is interpreted in a new light. It is suggested that gypsum primarily precipates at isolated points of evaporitic concentration, such as inland playas, and that deflation of evaporitic-rich
  • gypsum dust from these playas contributes to the formation of pedogenic gypsum duricrusts on the coastal gravel plains of the Namib Desert surrounding these playas. This study establishes the nature, extent and distribution of playas in the Central Namib
  • Desert and provides evidence for playa gypsum deflation and gravel plain deposition.
  • Playas and lunettes on the Southern High Plains: morphometric and spatial relationships
  • Croûte calcaire ; Dépression fermée ; Eau souterraine ; Eolien ; Etats-Unis ; Granulométrie ; Géomorphogenèse ; Géomorphométrie ; Hydrologie ; Lunette ; New Mexico ; Paléo-environnement ; Playa ; Quaternaire ; Statistique ; Texas ; Topographie
  • This paper provides a statistical description of the playas and assesses the relationships, if any, between playa variables and the occurrence of lunettes. Data were collected from a subset of 40 topographic maps, digitized on a GIS, and analyzed
  • using a nonparametric statistical procedure. The data support the hypothesis of playa development by erosion rather than by dissolution and subsidence. Lunettes form from deflation of calcareous playa fill which is more common in larger playas.
  • Salt ramps: wind-induced depositional features on Tunisian playas
  • Semicircular and crescent-shaped accumulations of salt crystals developed on salt crusts were measured on three Tunisian playas in September 1990. These features have been termed salt ramps. Their morphology and chemistry suggest
  • that they are formed in the late stages of shallow ephemeral lake dessication in playa basins. They appear to be short-lived features and their degradation is related to the flooding of playas with less saline water, and possibly rainfall and deflation.
  • Giant cracks and their formation on Willcox Playa in Sulphur Springs Valley, Arizona
  • Arizona ; Bilan hydrologique ; Domaine aride ; Eau souterraine ; Etats-Unis ; Fissure ; Géomorphologie ; Playa
  • Les fissures géantes sur les playas sont souvent attribuées à un profond déssèchement des sédiments faisant suite à une baisse du niveau de l'eau souterraine. Les fissures géantes de la playa Willcox ont un schéma orthogonal et proviennent de
  • Water induced sliding of rocks on playas Alkali Flat in big Smoky Valley, Nevada
  • Ecoulement ; Eolien ; Etats-Unis ; Géographie physique ; Géomorphodynamique ; Hydrodynamique ; Micromorphologie ; Nevada ; Playa ; Processus d'érosion
  • Field evidence, climatological data, and calculations based on physics prove that tracks on the Alkali Flat, caused by sliding stones (playa scrapers), result from subaquatic or at least inaquatic sliding. Driving force usually is the hydraulic
  • and helps to revise the common view of wind as the geomorphic agent on playa surfaces.
  • Origin and evolution of playas and blowouts in the semiarid zone of Tierra de Pinares (Duero Basin, Spain)
  • Caoudeyre ; Domaine semi-aride ; Duero basin ; Dépression fermée ; Erosion éolienne ; Espagne ; Géomorphologie climatique ; Playa ; Tierra de Pinares
  • Climatic geomorphology ; Closed depression ; Playa ; Semi-arid area ; Spain ; Wind erosion
  • Disposition géologique et géomorphologique : systèmes de terrasses, versants et leur évolution contrôlée par le climat. Accumulation éolienne. Les caoudeyres. Les playas : revue de la littérature, origine et évolution.
  • Der Überflutungsindex : ein Ansatz zur oberflächenhydrologischen Klassifizierung von Playas über das Satellitenbild (Beispiel: Alkali Flat, Nevada)
  • L'indice d'inondation: une approche de la classification hydrologique des playas à l'aide des images satellites (exemple: Alkali Flat, Nevada)
  • Classification ; Etats-Unis ; Hydrologie ; Image satellite ; Indice d'inondation ; Lac ; Nevada ; Playa ; Sédimentation
  • L'indice d'inondation peut être appliqué à la classification hydrologique des surfaces, par exemple pour séparer les playas des lacs ou encore pour différencier les playas entre elles. L'A. propose une tentative de classification des playas
  • Seasonal variations of saltation activity on a High Plains saline playa : Yellow Lake, Texas
  • Domaine aride ; Eolien ; Etats-Unis ; Humidité ; Playa ; Poussière éolienne ; Précipitation ; Texas ; Transport éolien ; Variation saisonnière ; Vent
  • Aeolian dust ; Aeolian features ; Aeolian transport ; Arid area ; Moisture ; Playa ; Precipitation ; Seasonal variation ; Texas ; United States of America ; Wind
  • This report is based upon a 4-yr. investigation of active aeolian processes at Yellow Lake,a saline playa within the Yellow House Basin, northwest of Lubbock, Texas. From December 30, 1998, to january 1, 2003, a fast-response piezoelectric saltation
  • sensor was used to collect a continuous record of aeolian activity at a point on the playa surface. Since saltation activity is often associated with dust emissions, the saltation record also provides information regarding seasonal patterns of dust
  • Facies identification within the playa-lakes of the Monegros desert, Spain, from field and satellite data
  • Aragón ; Domaine aride ; Désert ; Ecosystème aquatique ; Espagne ; Milieu humide ; Playa ; Salinité ; Typologie ; Télédétection
  • Aquatic ecosystem ; Aragón ; Arid area ; Desert ; Humid environment ; Playa ; Remote sensing ; Salinity ; Spain ; Typology
  • Un paléolac du Nord-Ouest mexicain: la Playa San Bartolo in Recherches françaises sur le Quaternaire.
  • Datation ; Géochronologie ; Géographie de l'Amérique ; Lac ; Mexique ; Niveau lacustre ; Paléoclimatologie ; Playa San Bartolo ; Sol salin ; Sonora ; Sédiment lacustre
  • Dans la Playa San Bartolo (Sonora Mexique), dépôts paléolacustres argileux à faciès d'évaporation intense, paléoniveaux avec faune de grands mammifères (Camélidé 7630460BP), présence de Planorbis sp. La datation de ces ossements permettra de savoir
  • si cette Playa à 29N reflète les paléoclimats du SW des USA: hauts niveaux lacustres entre 20000 et 11000BP, puis période aride. (PB).
  • Die geomorphologisch-bodengeographische Deutung der pleistozänen Sedimente und der fossilen Boden an der Playa de Baranan (westl. La Coruna) und bei Cangas de Foz (Nord-Galizien). (The geomorphological-pedological interpretation of the Pleistocene
  • sediments and fossil soils at the Playa de Baranan (W. of La Coruna) and near Cangas de Foz, N. Galicia)
  • Upper Pleistocene sediment-soil profiles were investigated from a rock basement at 3-5 metres u.s.l. and a coastal terrace at 25 metres u.s.l. at two sites in northern Galicia/north-west Spain (Playa de Baranan, west of La Coruna, and Cangas de Foz
  • Fan and playa areas in southern California and adjacent parts of Nevada
  • In bolsons in the desert regions of southern California and adjacent parts of Nevada, the area underlain by alluvial fan gravels and playa sediments is generally ∼ 1-2 times the area being eroded to produce those sediments. In certain larger basins
  • Soil dynamics and plant distribution of a sand dune playa michrochore catena after winter rain in the Wadi Araba (Jordan)
  • In this study, soil conditions and vegetation of different zones of a dune and an adjacent playa is described and correlated with plant density. Especially the water regime during the vegetation period (March until May) is investigated
  • Action éolienne ; Bibliographie ; Cône de déjection ; Domaine aride ; Désert ; Environnement ; Fleuve ; Géomorphologie ; Hydrologie ; Météorisation ; Pente de versant ; Playa ; Poussière ; Sédimentation
  • déjection; les playas des déserts,lacs et sabkhas de playas; les environnements éoliens des déserts : reliefs, processus et sédiments.
  • Application of AVHRR to monitoring a climatically sensitive playa. Case study : Chott el Djerid, Southern Tunisia
  • AVHRR ; Crue ; Domaine aride ; Lac ; Niveau lacustre ; Paléo-environnement ; Playa ; Précipitation ; Tunisie ; Télédétection
  • events and the presence of surface water on the playa, and for a limited sample of large flood events it was found that there were significant relationships between rainfall, evaporation and estimated lake areas. Overall, these data suggest
  • Quaternary environmental change in the western desert of Egypt : evidence from cave speleothems, spring tufas, and playa sediments
  • Climat ; Désert ; Eau ; Eau souterraine ; Egypte ; Holocène ; Oscillation climatique ; Playa ; Quaternaire ; Tuf
  • Climate ; Climate oscillation ; Desert ; Egypt ; Groundwater ; Holocene ; Playa ; Quaternary ; Tufa ; Water
  • Badain Jaran ; Chine ; Dune ; Désert ; Géographie de l'Asie ; Landsat ; Playa ; Radar ; SIR-A ; Télédétection
  • Morphologie des systèmes dunaires observés par Landsat et SIR-A. Les images Landsat montrent deux types dunaires différents| celles de SIR-A indiquent que la playa a été un lac intérieur beaucoup plus important.
  • La playa de Tabernes de Valldigna (Valencia)
  • Wind erosion on the north-eastern Tibetan Plateau : constraints from OSL and U-Th dating of playa salt crust in the Qaidam Basin
  • Bassin sédimentaire ; Chine ; Croûte de sel ; Datation ; Datation isotopique ; Domaine aride ; Eolien ; Erosion éolienne ; Géomorphologie ; Luminescence stimulée optiquement ; Playa ; Tibet ; Transport éolien
  • Aeolian features ; Aeolian transport ; Arid area ; China ; Dating ; Geomorphology ; Isotope dating ; Optically stimulated luminescence ; Playa ; Salt crust ; Sedimentary basin ; Tibet ; Wind erosion
  • Campo árido ; China ; Cuenca sedimentaria ; Datación ; Datación isotópica ; Erosión eólica ; Eólico ; Geomorfología ; Playa ; Tibet ; Transporte eólico
  • The aim of this paper is to constrain the timing of the formation of salt crusts and playas in the Qaidam Basin. Optically stimulated luminescence (OSL) and U-series dating from a pit section and from the top of a deep drill core, together
  • with results from magnetostratigraphy and a climate proxy record correlated to the marine oxygen isotope record, are used here to determine the age of the playa plains and suggest that the salt crusts have an age of c. 0.1 Ma. This young age and the wide
  • distribution of resistant thick salt crusts of the playa plains indicate a much lower degree of wind erosion than previously suggested. The crusts protect the surface from significant surface erosion (including sediment exhumation and unloading) and whilst some