ON THE ROLE OF KARSTIFIED REGIONS FOR UNDERSTANDING HOLOCENE CLIMATIC CHANGE IN INTERIOR CENTRAL EUROPE

The actual state of knowledge on Holocene climatic change in interior Central Europe is mainly based on investigations in humid regions providing a lot of lakes and mires. Deposits as peat and lacustrine sediments have enabled excellent conditions for applying well-tried methods of examination as e.g. pollen analysis. In contrast to these regions karstified ones are in want of such deposits and methodical possibilities. However, karstified regions offer other evidences of Holocene climatic change.

Mainly they are based on two groups of sedimentary sequences consisting of limestone detritus on the one hand an of freshwater lime deposits on the other one. A common feature of both these types of sequences is the lime content providing the preservation of calcareous fossils as bones and molluse shells. Therefore, in the Holocene sequences of karstified regions the methodical approach by means of pollen analysis may be replaced by palaeomalacology. Especially this methodical access has been qualified mainly by Czech scientists during the last century. The succession of mollusc assemblages reflects the change of palaeoecological conditions as well as pollen analysis in other regions, deposits, and sequences.

Frequently the evidence of fresh-water lime deposits includes and exceeds the indications of palaeomalacology, especially in discontinuous sequences. Fresh-water lime deposits comprise mainly calcareous tufa and marl. Discontinuous sequences are caused by the occurrence of buried humus horizons alternating with sedimentary layers in the stratigraphy. Frequently they appear in the exposures, and frequently their synchroneity can be proved by archaeological observations. Archaeological discoveries from the buried soils testify traces of ancient human settlement on previous subaeric surfaces intercalating the sedimentary sequences of subaquatic calcareous deposits.

Synchronuous datings prove that distinct time slices during the Holocene have favoured the drying of flat beaches and bottoms surrounding lakes and rivers in different karstified regios of Central Europe, alternating with others favouring a higher water level everywhere. This means that the alternation of calcareous sedimentary layers with buriel soils in the stratigraphy of fresh-water lime exposures reflects changing climatic conditions of regional validity.