Burnt Debris (IMAGE) University of the Basque Country Caption Pile of burnt debris of the Chalcolithic period unearthed at San Cristobal (Alava, Basque Country, Spain). Credit UPV/EHU Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.