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Geomorphic Features Associated with Erosion
Published in Ramesh P. Singh, Darius Bartlett, Natural Hazards, 2018
Niki Evelpidou, Isidoros Kampolis, Anna Karkani
Striations on the transferred rocks are generated by their friction against the glacial valley walls during their transportation by the glacier. Glacial striations are also apparent on the valley walls. The rugged and hard relief of the valley ground is rendered smooth, with striations parallel to the glacier movement.
Investigation of landslides
Published in E. N. Bromhead, The Stability of Slopes, 1992
Slip surfaces in clay soils may be found by locating the striated, or fluted, and polished surface (Figures 3.1 and 3.2) on which movement has taken place. The directions of the individual striations show the sense of movement on the slip surface, information which can sometimes be supplemented by noting the displacement of geological features such as marker beds. Roots can sometimes grow along slip surfaces, but may be dragged into a dog-leg shape by movement or they may be severed. Fresh slip surfaces in clay soils are almost invariably ‘polished’ or shiny. This is partly as a result of the alignment of platey clay mineral particles in the direction of shear, so that the slip surface is formed from the flat faces of myriads of clay particles, but is mainly a porewater phenomenon.
Drumlins in the Nordenskiöldbreen forefield, Svalbard
Published in GFF, 2018
Lis Allaart, Nina Friis, Ólafur Ingólfsson, Lena Håkansson, Riko Noormets, Wesley R. Farnsworth, Jordan Mertes, Anders Schomacker
Units of poorly sorted sands and gravels – unit 2 at site 1 and unit 1 at site 3 – are also interpreted to be glaciofluvial sediments. The poor sorting, the occurrence of lenses of planar cross-bedded sand and gravel with minor beds of sorted sand and silt suggest that the unit may be an ice-proximal glaciofluvial deposit (Miall 1977; Krüger & Kjær 1999). The interfingering of the different facies is explained by the braided river depositional environment. Similar facies associations have been found in Late Pleistocene drumlins in north-west Ireland (Dardis & Hanvey 1994). The random orientation of striations, the small-scale deformation of the fine material and the increased amounts of broken clasts indicate small-scale glaciotectonism, and that the sediments have been overridden by a glacier (Cheel & Rust 1986). The unit pre-dates the LIA advance of Nordenskiöldbreen. The origin is interpreted to be a proglacial outwash plain connected to a previous ice-margin east of the site. Additionally, the stratigraphic position of the unit at site 1 indicates a younger relative age than the glaciofluvial sediments described from sections 1 and 2.