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Periglacial and permafrost ground models for Great Britain

J. B. Murton and C. K. Ballantyne
Periglacial and permafrost ground models for Great Britain (in Engineering geology and geomorphology of glaciated and periglaciated terrains; engineering group working party report, J. S. Griffiths (editor) and C. J. Martin (editor))
Engineering Geology Special Publication (2017) 28: 501-597


Periglacial environments are characterized by cold-climate non-glacial conditions and ground freezing. The coldest periglacial environments in Pleistocene Britain were underlain by permafrost (ground that remains at or below 0 degrees C for two years or more), while many glaciated areas experienced paraglacial modification as the landscape adjusted to non-glacial conditions. The growth and melt of ground ice, supplemented by temperature-induced ground deformation, leads to periglacial disturbance and drives the periglacial debris system. Ice segregation can fracture porous bedrock and sediment, and produce an ice-rich brecciated layer in the upper metres of permafrost. This layer is vulnerable to melting and thaw consolidation, which can release debris into the active layer and, in undrained conditions, result in elevated porewater pressures and sediment deformation. Thus, an important difference arises between ground that is frost-susceptible, and hence prone to ice segregation, and ground that is not. Mass-movement, fluvial and aeolian processes operating under periglacial conditions have also contributed to reworking sediment under cold-climate conditions and the evolution of periglacial landscapes. A fundamental distinction exists between lowland landscapes, which have evolved under periglacial conditions throughout much of the Quaternary, and upland periglacial landscapes, which have largely evolved over the past c. 19 ka following retreat and downwastage of the last British-Irish Ice Sheet. Periglacial landsystems provide a conceptual framework to interpret the imprint of periglacial processes on the British landscape, and to predict the engineering properties of the ground. Landsystems are distinguished according to topography, relief and the presence or absence of a sediment mantle. Four landsystems characterize both lowland and upland periglacial terrains: plateau landsystems, sediment-mantled hillslope landsystems, rock-slope landsystems, and slope-foot landsystems. Two additional landsystems are also identified in lowland terrains, where thick sequences of periglacial deposits are common: valley landsystems and buried landsystems. Finally, submerged landsystems (which may contain more than one of the above) exist on the continental shelf offshore of Great Britain. Individual landsystems contain a rich variety of periglacial, permafrost and paraglacial landforms, sediments and sedimentary structures. Key periglacial lowland landsystems are summarized using ground models for limestone plateau-clay-vale terrain and caprock-mudstone valley terrain. Upland periglacial landsystems are synthesized through ground models of relict and active periglacial landforms, supplemented by maps of upland periglacial features developed on bedrock of differing lithology.

ISSN: 0267-9914
Serial Title: Engineering Geology Special Publication
Serial Volume: 28
Title: Periglacial and permafrost ground models for Great Britain
Title: Engineering geology and geomorphology of glaciated and periglaciated terrains; engineering group working party report
Author(s): Murton, J. B.Ballantyne, C. K.
Author(s): Griffiths, J. S.editor
Author(s): Martin, C. J.editor
Affiliation: University of Sussex, Department of Geography, Sussex, United Kingdom
Affiliation: University of Plymouth, Plymouth, United Kingdom
Pages: 501-597
Published: 2017
Text Language: English
Publisher: Geological Society of London, London, United Kingdom
ISBN: 9781786203021
References: 432
Accession Number: 2018-073437
Categories: Geomorphology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. geol. sketch maps, 1 table, sect.
N50°00'00" - N59°00'00", W08°00'00" - E01°30'00"
Secondary Affiliation: University of St. Andrews, GBR, United Kingdom
Country of Publication: United Kingdom
Secondary Affiliation: GeoRef, Copyright 2018, American Geosciences Institute. Reference includes data from The Geological Society, London, London, United Kingdom
Update Code: 2018
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