ORIGIN AND DEVELOPMENT OF THE NA TUROLDU CAVE SYSTEM

The Late Jurassic to Early Cretaceous Ernstbrunn limestones of the Pavlov Highlands are markedly affected by karstification and weathering processes which took place in several time periods. It is supposed that they began to weather already more than 100 million years ago in the Early Cretaceous period, when they turned into dry land due to sedimentation of clement layers of the Late Cretaceous and before the following marine transgression. At that time they were a part of the mountain belt that stretched from Austria to Northern Moravia. It was then that the first karst cavities were formed in limestones and simultaneously their dolomitization occurred. The following development of the karst phenomena continued only after incorporation of fragments of Mesozoic massifs into the Ždánice Unit and formation of the nappe structure during the main phases of the Alpine-Carpathian folding. The integrated underground cave system developed most probably 15 million years ago and later, after the Miocene phase of the Badenian. At that time the Badenian sea dereliction started the continuous continental development of the whole klippe, which is still going on to the present time. During the Tertiary period, however, limestones and the cave systems that formed with them were repeatedly disrupted by younger cross faults, the last echoes of the Alpine-Carpathian folding. Among the surface karst phenomena in the Turold quarry, there are remarkable smaller tower-like formations in the top section of the quarry and lapies developed on a small area east of the top. Before exhaustion of the quarry there was even a karst canyon and smaller karst ravines and gorges. The underground karst phenomena are traceable in two karts levels. The upper one is at the altitude of 365 m and there are caves such as Pod Vrcholem (Under the Top) and cavities in the northern quarry wall. The Na Turoldu Cave and the Liščí díra Cave with the vertical range of 295–250 m a.s.l. belong to the lower level. In the past there was even another cave between the two systems, namely the cave at the level of 330–320 m a.s.l. All the caves in the Turold quarry today just representfragments of the contiguous dewatering system that begins with the ponor cave Pod vrcholem. The major part of the system was, however, gradually destroyed during limestone quarrying.