Archaeological fieldwork techniques in Stone Age sites : some case studies - de la Torre, Ignacio (University College London. Institute of Archaeology) ; Arroyo, Adrián (University College London. Institute of Archaeology) ; Proffitt, Tomos (University College London. Institute of Archaeology) ; Martín Ramos, Carmen (University College London. Institute of Archaeology) ; Theodoropoulou, Angeliki (University College London. Institute of Archaeology)