THE PERIGLACIAL ZONE IN EUROPE DURING OXYGEN ISOTOPE STAGE 3 - COMPARISON OF CLIMATE MODEL RESULTS AND THE DISTRIBUTION OF PERIGLACIAL FEATURES

Ice wedge casts and periglacial involutions occur abundantly in deposits of Oxygen Isotope Stage 3 age in Europe north of approximately 50^o North latitude. Ice wedge casts are evidence of the existence of continuous permafrost. However, climate model results from the "Stage 3 project" are in conflict with the distribution of the periglacial features.

Based on conventional interpretation of paleotemperatures from ice wedge casts, the climate model results show mismatches up to 11^o C for the mean annual air temperature and up to 15^o C for the winter temperature. This mismatch is considerably reduced when locally favourable conditions and the time scale of ice wedge development are taken into account.Most likely the Stage 3 ice wedges represent very short (decadal) periods of intense cold.

It is difficult to discern the influence of climatic oscillations on the extension of Stage 3 permafrost zone. Thermokarst phenomena suggest widespread permafrost degradation during the Hengelo Interstadial. If episodical shifts of the permafrost zone did occur during Stage 3, this should have had consequences for drainage basin slope stability and fluvial processes. Fluvial data indeed indicate a widespread increase in fluvial sedimentation rate after establishment of permafrost conditions.