Malacofauna of Holocene calcareous sediments of the Cracow Upland

Abstract

The calcareous tufas and travertines of the Cracow Upland were formed in the Boreal, Atlantic and Sub-Boreal periods of the Holocene. The contained rich malacofauna testifies the variation and evolution of habitats in response to changing climatic conditions and the human activities. At the initial stage of calacrous deposition, the assemblages were not very distinctive. During the climatic optimum the content of forest snails increased markedly, then gradually decreased, and there appeared abundant species pointing to the progressing deforestation of the Upland. In the investigated profiles two types of facies sequences are distinguished, characterized by mollusc assemblages of different composition. One shows the predominance of species preferring moist, meadow and poorly wooded environments, the other contains the species inhabiting a variety of environments, including snails thriving in shaded habitats. Tufas and travertines were deposited on flat valley floors, in the midst of moist and watery meadows, brushwood and forests, as well as in water basins. In the Sub-Atlantic period erosional processes intensified, due to which the deposition of calcareous sediments was completed, and valley floors dissected and deepened to the present-day level.