Building stones used in early mediaeval edifices of Krakow and geology of the area

The early mediaeval period witnessed a considerable breakdown in masonry techniques and in architecture in the Polish territory: the application of stone and developing of skills of shaping rocks into regular cuboid stone bricks. Only local stones quarried within a distance of ca. 15 km from Krakow were used in early mediaeval edifices in the city. They were: two varieties of limestones (Upper Jurassic) and three varieties of sandstones of the Carpathian flysch (Cretaceous to Palaeogene). Sedimentary environments (facies) and post-sedimentary processes determined compactness, block divisibility and workability of stones, which, further on, determined their application. Thin bedded sandstone and platy limestone yielded easily workable and relatively small (few to a dozen of centimetres in length) and quite regular bricks used in the earliest buildings. Rocky limestone was a source of irregularly shaped clumps used initially as a filler of walls erected in the opus emplectum technique. Later, it was used also for cutting larger (few tens of centimetres), more regular blocks. Bedded limestone was a good material for obtaining larger (a dozen or two dozens of centimetres) regular bricks used widely throughout the whole early mediaeval period. Blocks (2 or more metres in length) of soft dimension Carpathian sandstone were used for shaping and carving large elements: tombstones, columns, volutes, epitaphs, etc. Techniques of quarrying and stone working developed considerable with time. Initially, slope scree and stone from demolished older ramparts were used. Later, quarries reached deeper beds which yielded larger bricks and blocks. Stone sources "migrated" with time too. The earliest places of excavation were located within the city, e.g. on the Wawel, Skałka and Krzemionki hills. When those deposits were exhausted, mining moved to more distant spots.