Journal ArticleDOI
Composite‐wedge pseudomorphs in Flanders, Belgium
Gunther Ghysels,Irenée Heyse +1 more
Reads0
Chats0
TLDR
In this article, large-scale polygonal crop marks underlain by sand-filled wedge structures cover extensive surfaces on the West Flanders plateau (Flanders, Belgium) and are interpreted as composite-wedge pseudomorphs, formed by thermal contraction cracking in a permafrost environment.Abstract:
Large-scale polygonal crop marks underlain by sand-filled wedge structures cover extensive surfaces on the West Flanders plateau (Flanders, Belgium). Wedge structures (∼1.0 m wide, up to ≥1.6 m deep) observed at several sites are interpreted as composite-wedge pseudomorphs, formed by thermal contraction cracking in a permafrost environment. The composite infilling points to former relatively dry conditions on the plateaus. Superimposed wedge structures may indicate discrete growth stages. The structures probably formed during the Pleniglacial (comprising Marine Isotope Stages 2–4), although an older age is not excluded. The widespread occurrence of composite-wedge pseudomorphs on the plateaus conflicts with the literature suggesting that ice-wedge pseudomorphs are dominant in Flanders. As a consequence, palaeoenvironmental reconstructions may have been biased towards environmental conditions suitable for ice-wedge formation. Ice wedges probably formed mainly in depressions, whereas composite wedges may have been common on the plateaus. Copyright © 2006 John Wiley & Sons, Ltd.read more
Citations
More filters
Journal ArticleDOI
Antarctic dry valleys: Microclimate zonation, variable geomorphic processes, and implications for assessing climate change on Mars
David R. Marchant,James W. Head +1 more
TL;DR: The Antarctic Dry Valleys (ADV) is a hyper-arid, cold-polar desert region as mentioned in this paper, which contains a suite of landforms at macro-, meso-, and microscales that closely resemble those occurring on the martian surface.
Journal ArticleDOI
Thermal contraction crack polygons on Mars: Classification, distribution, and climate implications from HiRISE observations
TL;DR: In this paper, the authors show that thermal contraction cracking of an ice-rich mantling unit is consistent with sediment wedge thermal contraction crack polygons forming in ice-cemented sediment at the Phoenix landing site.
Journal ArticleDOI
Thermal contraction crack polygons on Mars: A synthesis from HiRISE, Phoenix, and terrestrial analog studies
TL;DR: In this article, thermal contraction crack polygons are used to detect the presence of ground ice, ranging in ice content from weakly cemented soils to debris-covered massive ice, and their internal textural characteristics can be used to distinguish surfaces modified by the seasonal presence of a wet active layer or dry active layer, and delimit subsurface ice conditions.
Journal ArticleDOI
Water tracks and permafrost in Taylor Valley, Antarctica: Extensive and shallow groundwater connectivity in a cold desert ecosystem
TL;DR: Water tracks are zones of high soil moisture that route water downslope over the ice table in polar environments as discussed by the authors, and they represent a new geological pathway that distributes water, energy, and nutrients in Antarctic Dry Valley, cold desert, soil ecosystems, providing hydrological and geochemical connectivity at the hillslope scale.
Journal ArticleDOI
Distribution and chronology of Pleistocene permafrost features in France: Database and first results
Pascal Bertran,Eric Andrieux,Pierre Antoine,Sylvie Coutard,Laurent Deschodt,Philippe Gardère,Marion Hernandez,Claude Legentil,Arnaud Lenoble,Morgane Liard,Norbert Mercier,Olivier Moine,Luca Sitzia,Brigitte Van Vliet-Lanoë +13 more
TL;DR: The first OSL ages obtained from the aeolian infill of wedge structures indicate that at least two phases of thermal contraction cracking occurred in southwestern France between ∼25 and 36'ka.
References
More filters
Journal ArticleDOI
A New Roundness Scale for Sedimentary Particles
TL;DR: A new roundness scale is proposed defined by six roundness classes, defined by two sets of clay models prepared to characterize each roundness class and photographed to determine the roundness of a particle by comparison.
Book
The Periglacial Environment
TL;DR: In this paper, the authors present an overview of the periglacial domain and discuss the effects of permafrost on the global climate and its evolution. But they do not consider the effects on the local environment.
Journal ArticleDOI
Measurement and geological significance of shape and roundness of sedimentary particles
TL;DR: In this article, the shape and roundness of sedimentary particles are determined from the long, intermediate, and short diameters of the particles, and their roundness is measured by a rapid visual method.
Journal ArticleDOI
The Periglacial Environment
J. A. Steers,Hugh M. French +1 more
TL;DR: In this article, the authors present an overview of the periglacial domain and discuss the effects of permafrost on the global climate and its evolution. But they do not consider the effects on the local environment.
Book
The Periglaciation of Great Britain
TL;DR: The periglaciation of up-land Britain was studied in this article, where the authors showed that the periglacial mass-wasting and slope evolution in lowland Britain can be traced to fluvial and aeolian processes.