Age determination of runoff terrace systems in Petra, Jordan, using rock surface luminescence dating

An understanding of the early development of surface water control systems in Petra, Jordan, has thus far eluded investigators. While the Nabateans certainly used these extensively, it is not clear if they were the first to do so. In some areas in the headwaters of Petra in the Sharah Mountains, megalithic structures have been reported, with some investigators suggesting that they date back to the Iron Age. In this study, we investigate this issue using of quartz luminescence-depth profiles to date rock surfaces collected from a gabion (megalithic stepped terrace wall) at the site of Heash, Petra. Profiles from 5 cores from two rock samples show that quartz OSL signals were apparently fully bleached to a depth of 2 mm into the surface of the rocks used in construction of the terrace walls. Two other cores from the same rocks give an older age (3.3 ± 0.3 ka ago), compared to the other five (1.7 ± 0.2 ka ago). This indicates that structures at the site were initially constructed during the Iron Age, and experienced further development during the Late Roman/Byzantine period at ~ 300 CE, indicating the vitality and importance of the area. These dates are consistent with the pottery found at the site.