Stratigraphic and environmental implications of a large ice‐wedge cast at Tjæreborg, Denmark

• Published in: Permafrost and Periglacial Processes
• Main Author: Else Kolstrup
• Format: Article in Journal/Newspaper
• Language: unknown
• Subjects: permafrost
• Online Access: https://doi.org/10.1002/ppp.479

Exceptionally large ice‐wedge casts and composite‐wedge casts occur together with involutions (cryoturbations) in a gravel pit near Tjæreborg, western Jutland. The filling reveals distinctly different, vertically‐orientated sedimentary units, suggesting discrete events. Variations in wedge structure and infill between the different exposures suggest differences with alternating pools and drier conditions over the former wedges. In an attempt to date and correlate crack development a perusal of local glacial history is given and optically‐stimulated‐luminescence (OSL) dates are presented. A review of Saalian and early Weichselian wedge casts and deep involutions in other areas in northwest Europe is provided for correlation. It is suggested that the cracking in Tjæreborg took place during the Saale or/and early Weichselian. The existence of such old wedges shows that the present land surface has probably existed since the Saalian, leaving the ground available for cracking and infilling during succeeding periods of permafrost. Copyright © 2004 John Wiley & Sons, Ltd.