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Windpolished boulders as indicators of a late Weichselian wind regime in Denmark in relation to neighbouring areas
Author(s) -
Christiansen Hanne Hvidtfeldt,
Svensson Harald
Publication year - 1998
Publication title -
permafrost and periglacial processes
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.867
H-Index - 76
eISSN - 1099-1530
pISSN - 1045-6740
DOI - 10.1002/(sici)1099-1530(199801/03)9:1<1::aid-ppp271>3.0.co;2-x
Subject(s) - geology , katabatic wind , prevailing winds , period (music) , physical geography , holocene , climatology , geomorphology , paleontology , oceanography , geography , physics , acoustics
Fossil windpolished stones and boulders in in situ position have been found in various parts of Denmark. Typical wind abrasion microforms and mesoforms, such as facets and flutes, and the overall distribution of windpolished surfaces, have been studied on 31 in situ boulders at 20 locations in Denmark. Based on these investigations it is concluded that the direction of the former abrading winds was mainly from the ESE, from the sector 105°±20°. The ESE winds dominated during the deglaciation period, most probably in the period from 22 to 17 ka BP , when first katabatic and later zonal winds from the shrinking Weichselian Ice Sheet abraded surfaces of boulders in the periglacial environment outside the ice margin. During the subsequent Holocene period westerly winds dominated in a temperate climate, as is the case today. Best preserved windpolish is primarily found on boulders in boulder concentrations, whereas on the large erratic boulders the windpolish is often almost totally removed, owing to the many visitors climbing the boulders as well as weathering. Even on boulders transgressed by the sea for some time, windpolish has proved able to survive in low‐energy littoral environments. This yields opportunities for reconstructing palaeo‐wind directions in areas that are or have earlier been transgressed by the sea. Comparing the presented Danish palaeo‐wind evidence with neighbouring parts of north‐west Europe shows a regional variation in the wind regime, controlled by the extension of the Weichselian Ice Sheet. Dominating easterly palaeo‐winds prevailed as katabatic and/or zonal winds in a narrow zone in front of the wind‐controlling ice sheet during its maximum extension, and in some areas further to the east during the subsequent deglaciation. © 1998 John Wiley & Sons, Ltd.