Quartz use in the absence of flint: Middle and Upper Palaeolithic raw material economy in the Côa Valley (North-eastern Portugal)

Differing from most of European Upper Palaeolithic record, the Côa Valley lithic assemblages reveal an intensive use of a large variety of quartz and quartzite available locally. New surveys of the lower Côa Valley quartz veins were carried out in order to establish potential areas of raw material exploitation by hunter-gatherers through the identification of the raw material sources present in the archaeological record. Upper Palaeolithic lithic assemblages are produced on local quartz varieties, regional fine-grained quartz veins and flint and silcrete from long distance sources. The proportion of raw material and their choice for different tool types reveal some variation through the Upper Palaeolithic sequence, but present the same diversity and large geographical range of supply. Middle Palaeolithic assemblages from the same region are essentially based on local lithic material, showing a more restricted exploitation area and revealing different technology and procurement strategies, possibly evidence of changes in mobility and social networks.