Direct dating of a major rockfall at the Ba'ja Neolithic site (Jordan) using rock surface luminescence

Abstract

In this study, we use luminescence rock surface dating to provide burial ages for buried surfaces of a large boulder now positioned on top of the ruins of the Neolithic Ba'ja village in Southern Jordan. Luminescence depth profiles for quartz optically stimulated luminescence (OSL), and feldspar infrared stimulated luminescence (IR50) signals indicate that the boulder experienced a complex transport history of at least two exposure and two burial events before final emplacement. By comparing the fading-corrected feldspar IR luminescence burial ages derived from these rock surfaces with quartz OSL ages derived from sediment infill from the archaeological structures underneath the boulder, it is concluded that there was a rockfall event around 7–8 ka ago, possibly as the result of an earthquake. Whatever the nature of this event, it resulted in the first recorded movement of the boulder, when the rock was presumably dislodged on the hill slope but did not travel all the way to the settlement at the foot of the slope. About 3–4 ka ago, after the village had been abandoned and the rooms filled with rubble, further movement occurred, possibly initiated by an earthquake. This final transport event moved the boulder further downslope, embedding it in the cultural layers of the derelict settlement on top of the partially collapsed settlement walls.