Sands of Time - Relative and Absolute Luminescence Chronologies of the Early Islamic Plot-and-Berm Agroecosystem, Caesarea dunefield, Israel

In the face of increasing anthropogenic pressures on the Earth's surface, exploring ancient agricultural methods holds promise for innovative approaches, especially in traditionally considered less fertile landscapes like sandy landforms. The earliest documented instances of agricultural utilization on aeolian sand landforms are found in the form of Plot-and-Berm (P&B) agroecosystems along the present-day coastal plain dunefields of Israel.  The close to pristine state of a P&B agroecosystem in the hinterland of ancient Caesarea appears to have exhibited exceptional resilience. Here, following a survey, three excavation seasons (2020-2022) were conducted. The primary objectives of this study are : (1) Defining its spatial extent; (2) Explaining its agrotechnological innovation; (3) Providing a high-resolution, luminescence-based chronological analysis; and (4) Interpreting the motives for its development. Portable Optically Stimulated Luminescence (port-OSL) profiling was applied for chrono-stratigraphic analysis, discrete sample selection for OSL dating and a novel type of spatial analysis to determine development stages of the agroecosystem  

Covering 1.5 km², the Caesarea P&B agroecosystem features a checkerboard-like array of agricultural plots sunken between 3-10 meters high berms. The agroecosystem is neatly situated in the Caesarea dunefield lowlands between the shoreline and base of an aeolianite ridge, stream mouth brackish water in the south, and the ruins of Caesarea in the north. The agroecosystem ingeniously utilized refuse to stabilize loose aeolian sand and harness groundwater. Dark grey anthropogenic sedimentary units were enriched with fine-grained limekiln additives, reducing the infiltration rate of natural sand by filling the pores between sand grains. These morphological and sedimentological modifications sustained innovative annual irrigation methods in a Mediterranean climate.

Primary construction and agricultural activities were dated to the later part of the Early Islamic period, particularly the Fatimid caliphate (late 10th-late 11th centuries). The existence of the entire agroecosystem spanned ~200 years. This immense effort for cultivation indicates that the region flourished as the caliphate center relocated to Cairo. Additionally, this innovative agrotechnology was likely part of the large-scale "Islamic Green Revolution". Intermittent activity was noted during the subsequent early Crusader period (first half of the 12th century). Local evidence of reworking of anthropogenic sediments and aeolian sand deposits dating to Mamluk and Ottoman periods, is interpreted as periods of neglect.

Roman activity at the base of the berms suggested utilization of the dunefield during that era. Interestingly, during the Byzantine period, when Caesarea was at its peak, no activity was found, despite documented Byzantine utilization of sandy landforms in other areas like the Negev. This may suggest that during the Byzantine period, the aeolian system was active.

In summary, our investigation of the P&B agroecosystem at Caesarea reveals a pioneering approach to sustainable agriculture, marked by the ingenious use of refuse and limekiln fine-grain additives for groundwater and rainfall harnessing. Through coupled absolute and relative luminescence analyses, we trace its evolution from Roman times to the peak of the Fatimid caliphate, offering insights into resilient agricultural practices in less-fertile landscapes, pertinent to modern land-use challenges.