Na Pomezí Caves - Natural conditions
GEOLOGICAL DEVELOPMENT OF THE AREA
The complicated geological structure of the Králický Sněžník Mountains, the Hrubý Jeseník Mountains, the Rychlebské Mountains, the Hanušovická Highlands and the Zlatohorská Highlands is the result of long-term and complex development over the course of more than one billion years. During this period, most of the local rocks were intensely metamorphosed, i.e. converted into so-called crystallized rocks – crystalline complex.
To the west of the system of deep faults, with the so-called Ramzová Thrust crossing the Hrubý Jeseník Mountains in the NE – SW direction, lie rocks of the geological area of the Lužické Mountains, which are probably of Proterozoic origin. In an easterly direction from these faults there are rocks of the Moravian-Silesian Region probably formed in the Proterozoic to Early Paleozoic. Primarily marine sediments of rather mixed composition with interbeds of volcanites were intensely folded, broken and repeatedly metamorphosed, mostly as a result of the so-called Variscan (Hercynian) folding at the end of the Early Paleozoic. Part of the process included deep magmatism with results such as the Žulová massif composed of granitoids. Predominantly sedimentary rocks were converted to gneisses, mica schists, phyllites, graphitic shales, quartzites and erlans. Limestones and dolomites recrystallized under high pressures and temperatures to crystallized limestones – marbles. During that process the originally contiguous limestone formations were broken to smaller objects in which karst phenomena were formed by water during the following long-term processes.
Other outstanding changes and today's coarse appearance were imprinted in this area by the Alpine folding in the Tertiary. It restored movements on older faults, brought about the emergence of geological blocks and prepared conditions for the formation of today's mountain relief. Old karst phenomena in principle were destroyed and their new current appearance began to be formed.
Thicker layers of limestones with karst phenomena and caves emerged particularly in variegated formations of the so-called the Stroňská group in the Králický Sněžník massif and, to an even greater extent, in the so-called Branná area, forming an almost contiguous band from Olšany in the south up to the village of Lipová – lázně in the north (the Na Pomezí Caves are situated near the village). Here limestone islets of the metamorphosed mantle of rocks of the Žulová massif, such as Supíkovice marbles with the Na Špičáku Cave, are connected to them.