Black chert and radiolarite: knappable lithic raw materials in the prehistory of the Cantabrian Mountains (North Spain)

The Cantabrian Zone (N of Spain) is characterized by an occurrence of Palaeozoic age materials, mainly belonging to the Devonian and Carboniferous. Among the different lithologies, certain facies contain black chert and radiolarite in a total of 13 geological formations. Textural (de visu, stereomicroscope and thin sections), mineralogical (X-ray diffraction) and geochemical (X-ray fluorescence and inductively coupled plasma optical emission spectrometry) analyses have been carried out to describe the silicifications. All these data have made it possible to differentiate several varieties of chert and radiolarite that crop out in the Cantabrian Zone. Chert and radiolarite are raw materials that were used by the prehistoric groups that occupied this territory for thousands of years. The data obtained in this study will allow us to define the chert and radiolarite that appear in the archaeological sites in the Cantabrian region. Furthermore, some of these varieties appear in very restricted geographical areas, and therefore, these can be used as territorial mobility markers. With all this information, a precise definition of mobility patterns of prehistoric groups (Palaeolithic, Mesolithic and recent prehistory even to protohistoric times) in the Cantabrian region is achievable.