inscription
Portail d'information géographique

Résultats de la recherche (2887 résultats)

Affinez votre recherche

Par Collection Par Auteur Par Date Par Sujet Par Titre
  • Addition of aeolian dusts to soils in southeastern Australia : red silty clay trapped in dunes bordering Murrumbidgee River in the Wagga Wagga region
  • Aeolian dust ; Aeolian features ; Australia ; Clay mineral ; Climatic variation ; Dating ; Dune ; Grain size distribution ; New South Wales ; Palaeoclimate ; Quaternary ; Soil ; Soil properties
  • In southeastern Australia, aeolian dust deposits are very common and have a significant influence on soil properties and soil landscapes. However, the characteristics of the pure dust materials and the rates of dust-fall in the past are unclear
  • because of the low overall rate of dust deposition and mixing with locally derived sediments. In the Wagga Wagga region, some dunes have functioned as dust traps, and so provide an opportunity for characterising relatively pure dust deposits and evaluating
  • past dust deposition rates. Results and discussion.
  • Changing conditions of aeolian sand deposition during the last deglaciation period
  • Late Vistulian (= Weichselian) and Holocene aeolian phenomena in central and northern Europe
  • After the maximum of the last glaciation three main periods of aeolian activity may be distinguished : at the end of the Late Pleniglacial, in the middle of the Late Glacial (Older Dryas) and at the very end of the Late Glacial (latest part
  • Sand transport and deposition within arrays of non-erodible cylindrical elements
  • Aeolian features ; Aeolian transport ; Experimentation ; Grain size distribution ; Roughness ; Sedimentology ; Wind
  • This study concerns sand deposition within a regular array of vertical cylinders placed in the path of a sand-laden wind. 12 wind tunnel experiments using 3 preselected shear velocities, with associated rates of sand feed, and 4 roughness element
  • concentrations were carried out to evaluate the factors that affect sand deposition and sand flux in the presence of immobile rough elements. The sand deposition and sand flux along an array consisting of regularly distributed, non erodible elements were shown
  • Using quartz grain size and shape analysis to distinguish between aeolian and fluvial deposits in the Dallol Bosso of Niger (West Africa)
  • reworked by wind. Aeolian deposits were well sorted whereas fluvial deposits were poorly sorted in both size and shape. Although gross-shape characteristics (lower harmonics of Fourier series expansion) indicated a common source rock for all sands
  • Factor analysis of grain-size distributions gave four sand end-members that can be related to fluvial transport dynamics operating when the sediments were initially deposited. The medium to fine (and more angular shaped) sand fractions are being
  • , the aeolian sands were well rounded whereas the fluvial sands tended to be more angular (upper harmonics of Fourier series).
  • Coarse cliff-top aeolian sedimentation in Northern Gaspésie, Québec (Canada)
  • rockwall that forms the mountain's northwest side. The main results concern the local distribution and grain-size characteristics of the cliff-top aeolian deposits associated with this high magnitude event. Stratigraphic data and available radiocarbon dates
  • This paper describes the geomorphological consequences of a strong blizzard that occurred on 5 and 6 January, 1988. During this event, the summit of Mount Saint-Pierre (424 m) received a large amount of aeolian sediments originating from the shale
  • provide information concerning aeolian sedimentation rates for the last thousand years.
  • Human impact and intensity of aeolian processes in the Silesian-Cracow Upland (Southern Poland)
  • Late Vistulian (= Weichselian) and Holocene aeolian phenomena in central and northern Europe
  • and supremely intensifies possibility of forming aeolian deposits which are sometimes very disadvantageous from the sanitary point of view. It has also been stated that the degree of anthropogenic transformation of dunes does not change substantially.
  • It was found, that an early date human interference had caused local aeolian processes in the regions of substrates susceptible to deflation; however, contemporary human impact produces a great number of new sources of material deflation
  • Lithofacies variation and chronostratigraphy of Late Vistulian and Holocene aeolian phenomena in northwestern Poland
  • Late Vistulian (= Weichselian) and Holocene aeolian phenomena in central and northern Europe
  • , cover sands, and inland dunes and drift sands. TL and radiocarbon dating, pollen analysis and archaeological finds allowed to produce a chronostratigraphy of aeolian deposits and ovents in the study area.
  • In northwestern Poland within limits of the Poznań phase and Pomeranian phase of the last glaciation a considerable lithofacies variation of aeolian phenomena is to be observed. They are represented by ventifacts and sand-wedge fillings, loess
  • Aeolian blowout dynamics in subarctic Lapland based on decadal levelling investigations
  • Aeolian deflation ; Aeolian features ; Cold area ; Dune ; Finland ; Lapland ; Subarctic zone ; Vegetation ; Wind erosion
  • This work examines present-day blowout evolution processes by monitoring the erosion and deposition rates within selected deflation basins. The aim is to better understand the relationship between the present-day rates of aeolian activity
  • Environments of aeolian deposition in south-central Nebraska during the Last Glacial Maximum
  • Aeolian features ; Glacial features ; Loess ; Magnetic susceptibility ; Nebraska ; Permafrost ; Quaternary ; Stratigraphy ; United States of America
  • The Peoria Loess of south-central Nebraska, deposited approximately during the Last Glacial Maximum, can be subdivided into three zones: an upper laminated loess and a lower massive loess, separated by a dark gley zone in which bison bones
  • Aeolian dust transport and deposition by foehn winds in an alpine environment, Lake Tekapo, New Zealand
  • Aeolian features ; Aeolian transport ; Dust storm ; Erodibility ; Foehn ; Lacustrine basin ; Mountain ; New Zealand ; South Island ; Topography ; Wind erosion ; Wind speed
  • Observation from an automatic weather station and anemograph network are used in conjunction with recorded dust deposition rates to identify principle sources of wind blown dust within an alpine lake basin. Meteorological observations made
  • throughout the study indicate that foehn windstorms provide ideal conditions for the initiation of aeolian processes, including dust storm genesis. Potential dust roses were determined for 2 sites within the lake basin.
  • Danish Weichselian and Holocene aeolian deposits and their environment : a preliminary account
  • Late Vistulian (= Weichselian) and Holocene aeolian phenomena in central and northern Europe
  • developed in climatically and geomorphologically unstable environments, whereas drift sand may have developed following human activity. It is tentatively concluded that deposition of aeolian sediments took place periodically during the Pleniglacial and Late
  • Shorts accounts of Danish cover sand types, loess and drift sand are given. From palynological and geomorphological data it is attempted to establish a general outline of the environments during deposition. Cover sand and loess seem to have
  • The late Holocene coastal dunefield at Vejers, Denmark: characteristics, sand budget and depositional dynamics
  • Special Issue. Response of aeolian processes to global change
  • Aeolian features ; Coastal environment ; Denmark ; Dune ; Earth surface processes ; Holocene ; Jylland ; Model ; Sand ; Sedimentary structure ; Stratigraphy
  • The main purpose of this project is to map the large-scale 3D structure (sedimentary architecture) of the aeolian deposits and to develop an aeolian event stratigraphy for the late Holocene deposits. The second purpose is to calculate the sand
  • Sandy aeolian deposits and environments and their relation to climate during the Last Glacial Maximum and Lateglacial in northwest and central Europe
  • Aeolian features ; Bibliography ; Climate reconstruction ; Climatic variation ; Dune ; Europe ; Lateglacial ; Palaeo-environment ; Periglacial features ; Quaternary ; Sedimentology ; Stratigraphy ; Vegetation
  • This paper will concentrate on recent results and perspectives mostly related to relict Pleistocene aeolian deposits from the last glacial to interglacial transition in northwest and central Europe. It does not aim to give a full review
  • of the suject, but it highlights recent developments and new concepts and it gives possible directions for future research. Loess deposits and related environments are outside the scope of this paper.
  • Thermoluminescence dates and palaeoenvironmental information of the late Quaternary sand deposits, Tierra de Pinares, Central Spain
  • Aeolian features ; Arid area ; Castilla-León ; Dating ; Palaeo-environment ; Quaternary ; Sand ; Spain ; Thermoluminescence ; Wind
  • and palaeowind direction of the aeolian phases of sand deposition.
  • The focus of this paper, is a widely distributed sand which covers most of the Tierra de Pinares, north of Segovia. The AA. report the results of an investigation into the extensive sand deposits around Burgomillodo. They interpret the timing
  • Bias in grain size distribution of deposited atmospheric dust due to the collection of particles in sediment catchers
  • Aeolian dust ; Aeolian features ; Experimentation ; Grain size distribution ; Instrumentation ; Sedimentology ; Statistical bias ; Wind speed
  • This study investigates how dust deposition samplers affect the grain size characteristics of the sediment they catch. Some particle fractions are collected more efficiency than others, resulting in a modification of the original grain size
  • distribution of the sediment. This paper presents wind tunnel results for 5 dust deposition samplers and 5 wind velocities. The catcher's effect on the grain size was apparent in all experiences.
  • Dust deposition near an eroding source field
  • Aeolian dust ; Aeolian features ; Arid area ; Impact ; Model ; Quantitative analysis ; Texas ; United States of America ; Vegetation ; Water quality ; Wind erosion
  • This study was undertaken to quantify dust deposition within 200 m of a source field during wind erosion events. Erosion was measured with BSNE samplers on a small field of Amarillo fine sandy loam at field at Big Spring, TX. The line source model
  • seems useful in estimating both the pattern and quantity of deposition.
  • , and the mineralogical and geochemical characteristics of the deposited dust. Sediment supply to the lake source deposits involves fluvio-lacustrine transport of clays, with fluvial transport and salt weathering of silts and aeolian transport of sands. Subsequent aeolian
  • Harmettan dust deposition rates measured at Kano northern Nigeria during 1976-1979 range from 137 to 181 t/km/y. The characteristics and geomorphic history of the Chad Basin source deposits are inferred from the broad particle-size range
  • Simulated aeolian abrasion of pannonian sands and its implications for the origins of Hungarian loess
  • Eolian erosion ; Experimentation ; Grain size distribution;Granulometry ; Hungary ; Loess ; Microstructure ; Quaternary ; Surface deposits
  • This short study aims to examine experimentally the possibility that Pannonian sands can be reduced during aeolian transport to silt-sized material which resembles that found in loess and loess-like deposits. Results demonstrate the feasibility
  • Mineralogy of dust deposited during the Harmattan season in Ghana
  • Aeolian dust ; Aeolian features ; Aeolian transport ; Africa ; Clay mineral ; Geochemistry ; Ghana ; Mineralogy ; Sahara ; West Africa ; Wind
  • Nature and source of aeolian deposits near the summit of Ben Arkle, northwest Scotland
  • An extensive blanket of white sandy silt consists of recent windtransported material derived from frost-weathered quartzite regolith. Much of the weathered debris may have formed during the last Glacial period. Current aeolian reworking