Ancient trash mounds unravel urban collapse a century before the end of Byzantine hegemony in the southern Levant

Abstract

The historic event of the Late Antique Little Ice Age (LALIA) was recently identified in dozens of natural and geological climate proxies of the northern hemisphere. Although this climatic downturn was proposed as a major cause for pandemic and extensive societal upheavals in the sixth-seventh centuries CE, archaeological evidence for the magnitude of societal response to this event is sparse. This study uses ancient trash mounds as a type of proxy for identifying societal crisis in the urban domain, and employs multidisciplinary investigations to establish the terminal date of organized trash collection and high-level municipal functioning on a city-wide scale. Survey, excavation, sediment analysis, and geographic information system assessment of mound volume were conducted on a series of mounds surrounding the Byzantine urban settlement of Elusa in the Negev Desert. These reveal the massive collection and dumping of domestic and construction waste over time on the city edges. Carbon dating of charred seeds and charcoal fragments combined with ceramic analysis establish the end date of orchestrated trash removal near the mid-sixth century, coinciding closely with the beginning of the LALIA event and outbreak of the Justinian Plague in the year 541. This evidence for societal decline during the sixth century ties with other arguments for urban dysfunction across the Byzantine Levant at this time. We demonstrate the utility of trash mounds as sensitive proxies of social response and unravel the time-space dynamics of urban collapse, suggesting diminished resilience to rapid climate change in the frontier Negev region of the empire.

Keywords: Byzantine period; Late Antique Little Ice Age; ancient urban trash mounds; societal collapse; southern Levant.

Fig. 1.

(Left) Map of the Byzantine Empire at the beginning of the reign of Justinian in the year 527 CE (area in red), shortly before the territorial gains following from the Justinianic wars in Asia, Africa, and Europe. Black arrows represent the devastating territorial contraction of the Byzantine Empire in the wake of the Sasanian Wars and early Islamic conquests of the seventh century. (Right) Location map of the city of Elusa and Byzantine period village network of the Negev. Base map generated from intellectual property of Esri and its licensors and are used under license. Copyright © 2009–2019 Esri and its licensors. All rights reserved.

Fig. 2.

Survey, probing and excavation locations in Mounds M1 to M4 shown on an aerial photo of Elusa: circles 1–22, survey quadrants; triangles, dating probes; squares A–D, excavation trenches. Mound polygons in red identified from our DEM and the reconstructed outline of the ancient settlement taken from Saidel and Christopherson (23) (Fig. 5).

Fig. 3.

(Left) View of trash mound M1 of Elusa (Photo by G.B.-O.); (Center) 1.3-m-deep east section in Trench A, mound M1, with its sequence of alternating layers of dark and light color sediment (HA1–HA14) (Photo by R.S.-G.). Macroscopic signs of slight erosion were observed in the field in HA12 (red-dotted line: fine bedding of water-laid deposits) and in HA8 and HA2 (yellow-dotted line: possible wind-deflation of fine sediment particles leading to high abundance of macro charcoal pieces). (Right) Infrared spectra of the mineralogy of dark- and light-colored sediment layers. The darker-colored sediment of HA11 contained clay heated to temperatures between 500 and 600 °C, shown by the absence of clay hydroxyl groups in the 3,600-cm⁻¹ region [A: clay hydroxyl groups (OH) 3,697, 3,620 cm⁻¹], a leftward shift in the main clay peak from 1,035 to 1,045 cm⁻¹ [B: clay (Si-O-Si) 1,035–1,045 cm⁻¹], and the loss of the valley separating the clay peaks at 519 and 462 cm⁻¹ [C: clay (Si-O-Al) 519 cm⁻¹; clay (Si-O) 462 cm⁻¹]. The presence of ash in this sediment was evidenced by the characteristics of the calcite peaks [D: calcite (C-O) 875, 713 cm⁻¹], and the accompanying hydroxylapatite [E: hydroxylapatite (P-O) 605, 565 cm⁻¹]. Light-colored sediment from HA10 showed no signs of heated clay or ash, and the characteristics of its calcite peaks indicated that the mineral is of geogeninc origin. HA10 also contained mud fragments likely derived from mud mortar.

Fig. 4.

Distribution of period-sensitive ceramics from survey data (22 quadrants: 5 × 5 m) in the Elusa trash mounds, indicated by yellow polygons (identified in our DEM), surrounding the reconstructed outline of the ancient settlement [adapted from Saidel and Christopherson (23)] (Fig. 5). In each period map, filled rectangles represent the presence of diagnostic ceramics attributed to that temporal phase (notice orientation of northing arrow). (Lower Right) The P values of period to period differences of sherd occurrence from logistic regression analysis, showing a clear and significant peak in the early–middle Byzantine followed by a decline into the late Byzantine and continuing into the early Islamic period (*Hellenistic).

Fig. 5.

OxCal (54) plot of calibrated AMS carbon 14 dates from Trench A in mound M1 (five dates in stratigraphic succession) and in three 1 × 1-m excavation probes; charcoal, red dates (catalog numbers with asterisks); seeds, green dates (Materials and Methods and Fig. 2; wiggle-matching curve of the carbon 14 dates in SI Appendix, Fig. S4). See also ref. .