Yoav Avni

Archaeological investigations and OSL dating of terraces at Ramat Rahel, Israel

Abstract Dating terraces, the most prominent feature of the agricultural landscape in many parts of the world, is a problem for archaeologists. This study presents an interdisciplinary approach that combines archaeological survey and excavations with direct sediment dating of terrace fill using Optically Stimulated Luminescence (OSL). The study focuses on Ramat Rahel, a multi-period site located in the southern outskirts of modern Jerusalem, Israel, where, on a defined terraced slope chosen for a small-scale landscape archaeology project, three main phases of terrace construction and use were identified. The earliest phase dates to the Late Byzantine/Early Islamic period, the second to medieval times, and the last to the Ottoman period. The results enable a comprehensive reconstruction of the changing local landscape through time and demonstrate the validity of OSL, when combined with archaeological investigations, as a reliable method for terrace dating.

Byzantine–Early Islamic agricultural systems in the Negev Highlands: Stages of development as interpreted through OSL dating

Abstract An extensive survey followed by OSL (optically stimulated luminescence) dating of loess accumulation in agricultural terraces at six Byzantine and Early Islamic sites in the Negev Highlands revealed clear stratigraphic and chronological sequences. Traditionally dated to the 1st–7th centuries a.d., results from the present study demonstrate that the construction and use of largescale agricultural systems took place in the 4th–11th centuries a.d. This new chronology provides the framework for a more precise interpretation of the circumstances of construction and demise of largescale agriculture in the Negev Highlands. The agricultural fields were exploited continuously, yet ancient farmers had to confront the environmental hazards of occasional intensive floods, successive years of drought, and a constant process of loess accumulation and erosion. The constant maintenance and repair of fields necessitated an investment of labor. However, it seems that the expansion of ancient agriculture was part of the natural growth and development of Byzantine settlements in the Negev, and not the outcome of planned government enterprise. The agricultural systems were abandoned in the course of the 11th century a.d. and sporadically reused by pastoral nomads.

Use of airborne laser scanning to characterise land degradation processes – the Dead Sea as a case study

Abstract Evaluation of surface processes requires efficient means to quantify their effect. Despite the span and three-dimensionality of these processes, they are usually monitored using land surveying or naive 2D image interpretation. Therefore, the results are partial in terms of coverage and detail, and are mostly qualitative. We study in this paper the application of high resolution airborne laser scanning data for detection and characterisation of geomorphic processes. The Dead Sea region, where lake level drop of >1 m/year has led to dramatic change in the surrounding geomorphic system, and is endangering the natural environment and infrastructure, is used here as our case study. We propose a feature extraction methodology which responds to the measurement noise and surface texture and show how laser data are optimal for detecting such phenomena, accurately characterising them and providing quantitative data, which are all necessary to understand their development.

Late Quaternary deposition and erosion processes along the margins of the Yamin Plain, northeast Negev, Israel

Dody, A., Nahlieli, A., Avni, Y., Cohen, H., Weiner, D., and Porat, N. 2008. Late Quaternary deposition and erosion processes along the margins of the Yamin Plain, northeast Negev, Israel. Isr. J. Earth Sci. 57: 199–211. This study presents rates of accumulation and transport of sands as well as rates of incision along the margins of the Yamin Plain, northeastern Negev, and evaluates the stability of the present landscape. Geomorphological mapping, OSL and 14C dating, and sedimentological analyses suggest that rates of erosion range between ~45 mm/year in the eastern side of the study area and 0.05 mm/y on the western side. The calculated erosion rates show that, until recently, geomorphic processes in the eastern part of the plain were dominated by accumulation of sands derived from the Hazeva Group. However, accelerated erosion is observed near the contact between the sand units and the carbonate bedrock of the Judea Group. It appears that the area west of the plain has been stable during the last glacial (circa 73–18 ka). We suggest that the exclusion of domestic grazing from the Yamin Plain in the 1950s changed the balance between erosion and sedimentation and caused accelerated erosion mainly in the eastern part of the Yamin Plain by decreasing infiltration and increasing runoff.