Skład mineralny osadów calca i gruntów poziomów użytkowych Rynku Głównego w Krakowie jako odzwierciedlenie jego zmian funkcjonalnych

MINERAL COMPOSITION OF BEDROCK DEPOSITS AND UTILITY LEVELS IN MAIN MARKET SQUARE IN KRAKÓW AS A REFLECTION OF THE FUNCTIONAL TRANSFORMATIONS OF THE PLAZA The study presents selected profi les of the layers of the ground as well as the bedrock deposits underneath these layers, unearthed below the surface of Main Market Square (Rynek Główny) in Kraków. The survey concentrated on the presence of the mineral phases of anthropogenic origin, which were used as a basis to determine the types of activity that could have contributed to their formation and to establish how the material had been transferred to the ground. Special attention was devoted to the utility levels, such as cobbled surfaces and narrow baulk-like passages (miedzuch), or dirt floors, whose composition refl ects the character and purpose of given area. The survey was based on three profi les of bedrock deposits available through bores in diff erent sections of the underground vaults in the Square. Th e distribution of the boreholes was connected with the establishment of piezometers necessary for wide-ranging tests of the quality of subterranean waters in the old part of Kraków. The deposits bored to the maximum depth of approximately 6 metres [19 ft] below the thill of the fills, represented by sands and gravels, are the remains of oxbow lakes. The occurrence of material of diff erent origins points to the formation of deposits within the areas aff ected by the Vistula River itself as well as its upland tributaries. The average granular composition of samples is similar for all the boreholes; the sand fraction prevails (88 to 90 per cent), and substantial density of the material is observed. The thickness and the granular composition of the deposits evidences that the penetration of solutions from the upper layers can be difficult and probably takes place within the roof of the bedrock. The mineralogical formations deposited in the bedrock were tested on the basis of the samples from archaeological layers of the unaltered soil profile B2 in the northern annex. Apart from information about the distribution of anthropogenic phases among the historical layers and fills, the results of the planimetric tests revealed that the most suitable fraction for analyzing mineral components and micro-artefacts is the granular fraction with grain size between 0.5 and 1 mm [0.02 to 0.04 in]. One of the observations made during the analysis was the penetration of solutions through the archaeological layers and washing out iron and manganese from these layers to the bedrock deposited below the anthropogenic layers in the area of the Square. The determination of the composition of the layers evidences intensive transformation of the functions of the analyzed sites. The interdisciplinary study shall continue, as the most reliable defi nition of the genesis of the archaeological layers can only be arrived at as a result of a parallel interpretation of the research, most suitably carried out on an ongoing basis.