The first stages of erosion by ice sheets: Evidence from central Europe

Hall, Adrian M.; Migoń, Piotr

doi:10.1016/j.geomorph.2010.08.008

Cited by 27 publications

(21 citation statements)

References 55 publications

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“…11E). A study in the Sudetes region (central Europe), only covered once by glaciation, gives an idea of such 'first glaciation' erosion in a granite-dominated terrain (Hall and Migoń, 2010 (Clark and Pollard, 1998;Roy et al, 2004a, b).…”

Section: Variability Of Glacial Modificationmentioning

confidence: 99%

Quaternary evolution of glaciated gneiss terrains: pre-glacial weathering vs. glacial erosion

Krabbendam

Bradwell

2014

Quaternary Science Reviews

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Vast areas previously covered by Pleistocene ice sheets consist of rugged bedrock-dominated terrain of innumerable knolls and lake-filled rock basins -the 'cnoc-and-lochan' landscape or 'landscape of areal scour'. These landscapes typically form on gneissose or granitic lithologies and are interpreted (1) either to be the result of strong and widespread glacial erosion over numerous glacial cycles; or (2) formed by stripping of a saprolitic weathering mantle from an older, deeply weathered landscape.We analyse bedrock structure, erosional landforms and weathering remnants and within the 'cnoc-andlochan' gneiss terrain of a rough peneplain in NW Scotland and compare this with a geomorphologically similar gneiss terrain in a non-glacial, arid setting (Namaqualand, South Africa). We find that the topography of the gneiss landscapes in NW Scotland and Namaqualand closely follows the old bedrock-saprolite contact (weathering front). The roughness of the weathering front is caused by deep fracture zones providing a highly irregular surface area for weathering to proceed. The weathering front represents a significant change in bedrock physical properties. Glacial erosion (and aeolian erosion in Namaqualand) is an efficient way of stripping saprolite, but is far less effective in eroding hard, unweathered bedrock. Significant glacial erosion of hard gneiss probably only occurs beneath palaeo-ice streams.We conclude that the rough topography of glaciated 'cnoc-and-lochan' gneiss terrains is formed by a multistage process: 1) Long-term, pre-glacial chemical weathering, forming deep saprolite with an irregular weathering front;2) Stripping of weak saprolite by glacial erosion during the first glaciation(s), resulting in a rough land surface, broadly conforming to the pre-existing weathering front ('etch surface');3) Further modification of exposed hard bedrock by glacial erosion. In most areas, glacial erosion is limited, but can be significant beneath palaeo-ice stream. The roughness of glaciated gneiss terrains is crucial for modelling of the glacial dynamics of present-day ice sheets. This roughness is shown here to depend on the intensity of pre-glacial weathering as well as glacial erosion during successive glaciations.

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Section: Variability Of Glacial Modificationmentioning

confidence: 99%

Quaternary evolution of glaciated gneiss terrains: pre-glacial weathering vs. glacial erosion

Krabbendam

Bradwell

2014

Quaternary Science Reviews

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“…Where remnants of this weathering mantle survive widely, then glacial erosion has been largely confined to removal of saprolith and must also be b20 m deep. Such remnants occur widely and their distribution correlates with other geomorphic indicators of preglacial relief inheritance and the weak development of glacial landforms in bedrock in eastern Canada (Bouchard et al, 1995;Jansson and Lidmar-Bergstrom, 2004), Greenland (Sugden, 1974), northeast Scotland (Hall and Sugden, 1987), southern Sweden , 1999, northern Sweden (Ebert et al, 2015), western Finland (Söderman, 1985), southern Poland (Hall and Migoń, 2010), and northwest Russia (Evzerov et al, 2007). Interpretation of isolated pockets of shallow gruss and saprock found in zones of more advanced glacial erosion, including streamlined and knock and lochan landscapes, is more difficult (Godard, 1989).…”

Section: Implications For Glaciation Of Northern Shieldsmentioning

confidence: 95%

“…These views derive largely from observations that thick kaolins and bauxites of Palaeozoic to Palaeogene age are found today along shield margins. These intensely weathered rocks are, however, confined largely to locations beneath and close to sedimentary and volcanic cover rocks along shield margins (Kaye, 1967;Parham, 1970;Smith, 1987;Lidmar-Bergström, 1995;Mordberg and Nesterova, 1996;Sarapää, 1996;Lidmar-Bergström et al, 1997;Patterson and Boerboom, 1999;Cravero et al, 2010;Hall and Migoń, 2010). Pockets of intense weathering are not widely reported from shield interiors.…”

Section: Comparisons With Other Glaciated Shields and Platformsmentioning

confidence: 99%

Late Cenozoic deep weathering patterns on the Fennoscandian shield in northern Finland: A window on ice sheet bed conditions at the onset of Northern Hemisphere glaciation

2015

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“…In the highest part of the Sudetes conditions were suitable for the development of local glaciation (Engel et al 2010). Marginal parts of the Sudetes were twice reached by the Scandinavian ice sheet, but its erosional and depositional effects are relatively minor (Hall & Migoń 2010). …”

Section: The Areamentioning

confidence: 99%

Rediscovering geoheritage, reinventing geotourism: 200 years of experience from the Sudetes, Central Europe

Migoń

2014

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The Sudetes is a mountain range in Central Europe and an area of remarkable geodiversity. In recent years, the area has been promoted as a geotourist destination and various initiatives aimed at better understanding geoheritage have been implemented. An interest in scenic landscapes is not new however, and dates back to the end of the eighteenth century. Two areas within the Sudetes are cradles of local nature-based tourism. These are the granite massif of the Karkonosze in the west and the sandstone stepped plateau of Broumov Highland and Stołowe Mountains in the central part of the Sudetes. In both, physical access to the key geosites was provided as early as in the nineteenth century, while an interpretation component was added in the early twentieth century. A side-effect of political change following the end of World War II was the neglect and dilapidation of many sites, as well as the disappearance of geoheritage appreciation from the collective social memory. In the last decade many of those early achievements were rediscovered and provided the foundations for contemporary activities. An educational component based on modern science is now included in the features which were discovered as tourist attractions long ago.

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The first stages of erosion by ice sheets: Evidence from central Europe

Cited by 27 publications

References 55 publications

Quaternary evolution of glaciated gneiss terrains: pre-glacial weathering vs. glacial erosion

Quaternary evolution of glaciated gneiss terrains: pre-glacial weathering vs. glacial erosion

Late Cenozoic deep weathering patterns on the Fennoscandian shield in northern Finland: A window on ice sheet bed conditions at the onset of Northern Hemisphere glaciation

Rediscovering geoheritage, reinventing geotourism: 200 years of experience from the Sudetes, Central Europe

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