engleski

Possible cryogenic origin of some kamenitzas

Origin of kamenitzas is usually attributed to leaching of limestone by aggressive meteoric water, sometimes under pedogenic cover. However, this rather simple process does not explain their position on tops of boulders and on flanks of rillen-karren where meteoric water could not accumulate. Some kamenitzas on southern Velebit Mt. and northern Adriatic islands occur on top of boulders which have not been buried under vegetated soil, a prerequisite for formation of initial depression which could continue to grow by biochemical corrosion to achieve their characteristic overhang rim. These kamenitzas have formed on bare boulder tops where there was no primary accumulation of water, on the rock surfaces exposed to strong winds on sun-exposed rock faces which facilitate efficient evaporation. So, how were these karst forms created? Some kamenitzas are also formed on steep rock faces which are sculptured by sharp rillen-karren, and are apparently younger in origin, since the contact between the two is sharp and their stratigraphic relationship is very clear. How were these kamenitzas formed, when all rainwater rapidly drains down the rock face? The described kamenitzas must have been formed by other processes than those described in literature [1]. We herein propose an alternative explanation which involves accumulation of snow, and cryogenic destruction of the host rock by freezing water. This process is essentially mechanical, and may form initial depressions in any position on the host rock, and will eventually form overhang rims by repeated freezing and thawing of frozen water surface, as described in the poster.

karstification, grikes, geomorphology, palaeoclimate

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