Ph.D. thesis

Quaternary karst in the valley of Rusenski Lom River and its tributaries

The aim of this investigation is a description of the young karst forms and establishing their genesis and age in the valley of Rusenski Lom River and its tributaries - Cherni Lom River, Beli Lom River and Malki Lom River (NE Bulgaria). The last stage of karstifikation is determined from Late Romanian Time until our days by study on geological features and surfaces. The past conditions and development of the valley during the last stage of karstification are established by investigating alluvium, loess-paleosol sequence and river terraces. Four units in the river deposits are separated and they are correlated with sediments in the Late Romanian - Young Pleistocene basin. Fourteen river terraces are recorded.The ages of most of them are determinate.
The known 56 caves in the region are described in details and systematized in a new classification on the base of their morphogenetic features. The structural and hydraulic control on forming the caves, their genesis and some regularities of karst are recognized. A new genetic model for Orlova Chuka Cave is propounded. The sediment sequences in five sites in the Orlova Chuka Cave are analyzed and lithofacial types are set off. Paleoclimatic record of one of the sites is studied by comparing some physical parameters - grain size, carbonate content, magnetic susceptibility and organic carbon content. 579 remnants of micromammals and an individual of Ursus cf. deningeri have been found into the sediments from the same site. The remnants of micromammals present minimum 35 species of orders Insectovora, Lagomorpha, Rodentia and Chiroptera. The results of paleoecological analysis of micromammals conform the results of comparing the physical parameters. They manifest alternation of periods of cold and arid, cold and humid, and temperate climate in general cold conditions during depostion.

Last Update: December 17, 2005

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