Raw material as fossile directeur? A case study of the use of Stránská skála-type chert.

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.