The Stránská skála-type chert is a local Moravian chert of Jurassic age, which is available only within a limited area restricted to the Stránská skála rock outcrop and secondary sources in nearby gravels. As this raw material has been well-studied petrographically, its distribution is easy to trace. Its use and proportions within individual archaeological assemblages in particular vary over time -ranging from the dominant raw material during several chrono-cultural periods to a complete absence of this raw material in other periods. Periods of significant use include the Initial and Early Upper Palaeolithic, Late Neolithic and Early Eneolithic. Less pronounced evidence of distribution is also known from the Late/ Final Eneolithic and from the Early Bronze Age. Periods of no use include the Middle to Late Upper Palaeolithic, Early -Middle Neolithic and Middle Eneolithic. This raw material was mostly used locally with a limited distribution -the maximum extent of its occurrence is a few tens of kilometres from the source outcrop. The Stránská skála-type chert should be accepted as a fossile directeur sensu lato thanks to its easy determination and the isolation of the outcrop in combination with the techno-typological analysis.
INT RODUCTIONStránská skála (Fig. 1) is an isolated raw material (the Stránská skála-type chert) outcrop on the eastern edge of the Brno Basin has been well-studied petrographically (Přichystal 2009;2019), so its distribution is easy to trace (cf. Bartík et al. 2019;. Although there are other occurrences of limestones of Jurassic age with petrographically almost identical cherts (e.g. Bílá hora, Hády, or Švédské šance) and similar cherts appear in gravels in the vicinity of Stránská skála (with characteristic pebble cortex), the prevailing volume of cherts of that type in the Palaeolithic assemblages unequivocally came directly from the Stránská skála outcrop.The Stránská skála-type chert represents a local raw material that was utilized during the entire Stone Age with peaks at the beginning of the Upper Palaeolithic (Přichystal/Svoboda/Škrdla 2003) and during the Late Neolithic -Early Eneolithic periods (Bartík et al. 2019). In contrast, its marginal use was documented during the Late Upper Palaeolithic (Přichystal 2002;Svoboda et al. 2020), Late Eneolithic (Kopacz ed. 2019) and Early Bronze Age (Kopacz/Šebela 2006). This raw material (and the Brno Basin itself) went almost completely unnoticed during the Mid Upper Palaeolithic (Gravettian), Late Upper Palaeolithic, Mesolithic and Early/Middle Neolithic (LBK, STK; Fig. 2).
M AT ER I ALS A N D MET HODSAs mentioned above, the Stránská skála-type chert comprises characteristic features within its texture, including whitish enclosures (fragments of microfossiles), dark sponge spicules, rectangular cavities after dissolved crinoidal segments and banding. Although some of the features mentioned above allow the identification of this material on the macroscopic level, stereomicroscopy using immersion liquid provides an even more precise diagnosi...