Earliest known coastal seawall uncovered at Neolithic settlement Tel Hreiz

11-Dec-2019 3:15 PM EST


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Newswise — Possibly one of the first attempts to protect against sea-level rise in a human settlement is described in a study published December 18, 2019 in the open-access journal PLOS ONE by Ehud Galili from the University of Haifa, Israel, and colleagues.

At least sixteen submerged Neolithic settlements from 9000-6500 years ago have been discovered along the Mediterranean Sea coastline in what is now northern Israel. In this study, Galili et al. investigate the Tel Hreiz settlement (7500-7000 BP), specifically the linear boulder feature exposed after winter storms in 2012 and 2015. Following the feature’s identification in 2012, Galili et al. measured, photographed, and documented its location before the sea and weather re-covered the site with sand. In 2015, another storm partially-uncovered the structure, allowing the authors a second opportunity to investigate the site. 

The boulder feature stretches over 100m along the western, seaward side of Tel Hriez, three meters below sea level and 90m offshore in what would have been the “swash zone” (alternately covered and exposed by incoming waves) during occupation. Most of the structure is composed of large, rounded boulders of aeolianite and limestone, neither of which occur naturally near the site, deliberately placed in a line to form a wall.  

The wall’s location and structure indicate that it was a seawall, separating and protecting the main part of the settlement from the open sea and coastline. A Late Bronze Age seawall (3100-3500 BP) three kilometers south of Tel Hreiz shares similar limestone boulder construction and shape, bolstering this conclusion. The effort required to transport the seawall’s boulders to Tel Hriez likely required planning, coordination, and hard work—the nearest sources of boulders this material and size are the Oren and Galim Rivers (3.8km south and 1.6km north, respectively).

The authors note that during the post-glacial sea rise of the Neolithic, the Mediterranean coast experienced sea level rises of 12-21cm approximately every 30 years, meaning that the frequency of destructive storms increased noticeably over the centuries of occupation at Tel Hreiz. Despite the work put into this seawall, in the end it proved unable to hold back the advance of the Mediterranean Sea, and Tel Hreiz was abandoned to the water. 

The authors add: “There are no known or similar built structures at any of the other submerged villages in the region, making the Tel Hreiz site a unique example of this visible evidence for human response to sea-level rise in the Neolithic.”



Press-only preview: https://plos.io/2PDRK8y

Image Captions: (a) a scale plan of the Tel Hreiz site showing location of site finds and the boulder-built seawall: (1) rectangular structure (possible dwelling). (2) two parallel wall fragments. (3) curved structure. (4-5) round structures. (6-7) concentrations of wooden posts (no. 6 was 14C dated). (8) burial 1 (14C dated). (8) burial 2. (10) stone-built cist grave. (11) boulder-built sea wall. (12) hearth with wooden bowl (14C dated). (13) domestic cattle mandible (14C dated). Fig 2: (b) photograph of the ‘dogleg’ in the Tel Hreiz boulder-built wall looking south-east. Fig 2: (c) detail of the ‘dogleg’ (E. Galili and J. McCarthy).


Image Credits: Galili et al, 2019.


In your coverage please use this URL to provide access to the freely available article in PLOS ONE http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0222560


Citation: Galili E, Benjamin J, Eshed V, Rosen B, McCarthy J, Kolska Horwitz L (2019) A submerged 7000-year-old village and seawall demonstrate earliest known coastal defence against sea-level rise. PLoS ONE 14(12): e0222560https://doi.org/10.1371/journal.pone.0222560


Funding: E.G and J.B recieved a grant from the Honor Frost Foundation 2017: Sea level rise and human response in the Neolithic: evidence for coastal defence.


Competing Interests: The authors have declared that no competing interests exist.