About the building stone of the Pskov lands in the Middle Ages

The authors studied the lithological and facies features of Upper Devonian carbonate rocks developed in the vicinity of the cities Pskov and Izborsk and compiled a list of criteria that allow macroscopic diagnostics of limestone differences in the objects of historical and cultural heritage of Pskov and Pskov lands. The nature of the building material used in the objects of defense architecture of the medieval period of the region is analyzed. The analysis has demonstrated the interrelation of the features of the geological structure and building materials of fortifications of the Pskov lands. The lack of stone building materials partly determined the construction of exclusively wooden and earthen-wooden fortresses in the south of the region (the area of development of carbonate, terrigenous-carbonate and terrigenous rocks of the Middle and Upper Frasnian, overlain by a thick layer of the Pleistocene sediments). The construction of the northern fortresses (Izborsk and Pskov), located in the area of the development of carbonate rocks of the Lower Frasnian, exposed in the banks of the lower reaches of the Velikaya River and its tributaries, was in stone. The accelerated construction time of the Pskov fortress and the development of rocks of the same stratigraphic level in the immediate vicinity of ancient Pskov led to a lack of criteria for choosing the stone material used. The Gdov fortress was the first and only defense of Pskov’s lands from the north, which was due to the emergency construction of the Gdov fortress in stone, although the geological situation in Gdov (the area of development of terrigenous rocks of Eifelian and Givetian, in most of the territory overlain by the Quaternary deposits) also did not favor the widespread development of stone building materials. The nature of the boulder material found in the surviving fragment of the Gdov fortress wall suggests that terrigenouse material from moraine deposits was actively used for construction.

Main Devonian Field, Upper Devonian, Lower Frasnian, building stone, facing stone, fortresses of medieval Pskov