7,000-year-old seawall, built to block rising sea levels, found off Haifa coast
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ArchaeologyPredates other ancient breakwalls by 3,000 years

7,000-year-old seawall, built to block rising sea levels, found off Haifa coast

With discovery of world’s oldest known breakwater, archaeological record shows how Neolithic villages tried – sometimes in vain – to protect their homes from melting glaciers

Amanda Borschel-Dan is The Times of Israel's Jewish World and Archaeology editor.

Photographs of finds from the Tel Hreiz settlement. (a-b) exposure of stone-built features in shallow water. (c) wooden posts dug into the seabed. (d) bifacial flint adze. (e) in situ stone bowl made of sandstone. (f) in situ basalt grounding stone (scale = 20cm); (g) burial 1. (h) suspected stone built cist grave - view from the east (scale = 20cm). (i) in situ antler of Mesopotamian fallow deer, Dama dama mesopotamica. (All photographs by E. Galili with the exception of Fig 3G by V. Eshed)
Photographs of finds from the Tel Hreiz settlement. (a-b) exposure of stone-built features in shallow water. (c) wooden posts dug into the seabed. (d) bifacial flint adze. (e) in situ stone bowl made of sandstone. (f) in situ basalt grounding stone (scale = 20cm); (g) burial 1. (h) suspected stone built cist grave - view from the east (scale = 20cm). (i) in situ antler of Mesopotamian fallow deer, Dama dama mesopotamica. (All photographs by E. Galili with the exception of Fig 3G by V. Eshed)

An international team of underwater archaeologists has uncovered the oldest known manmade seawall off the coast of Haifa, according to an article published in the Public Library of Science’s scientific journal PLOS ONE.

The ancient seawall is located at the underwater archaeological site of Tel Hreiz, a Neolithic settlement that thrived near today’s Haifa from circa 7500-7000 years ago. According to the article’s authors, the wall was constructed to stave off ever-rising sea water from melting glaciers. It predates other ancient breakwalls by 3,000 years.

“The seawall is unique for the period and is the oldest known coastal defense worldwide,” write the group of researchers from University of Haifa, Flinders University in Australia, the Israel Antiquities Authority and The Hebrew University.

The wall was first discovered in 2012. After years of study, the researchers concluded that the residents constructed the over 100-meter-long seawall from boulders of up to 1 meter in size that were taken from riverbeds some 1-2 kilometers from their village. The large boulders were from limestone or kurkar stone and weigh between 200-1000 kilograms each.

The zigzagging seawall was intentionally planned and constructed with several different building styles to keep out the rising water, write the authors. “Notably, for its entire length, it is free-standing… the wall is not attached to any domestic structure in the village,” they write.

Location maps: (a) Eastern Mediterranean and the Israeli coast; (b) submerged Neolithic settlements off the Carmel coast (drawing J. McCarthy after Galili et al. 2019, modified after Natural Earth https://www.naturalearthdata.com in the public domain)

Unfortunately, said Dr. Ehud Galili from the University of Haifa’s Zinman Institute of Archaeology, the extreme measure to protect the village did not pay off and the residents had to eventually abandon their homes.

In a press release, Galili explained that during the Neolithic era, people living along the Mediterranean would have experienced a sea-level rise of approximately 12-21 centimeters during a lifetime, which works out to be around 70cm in a 100 years. Ancient Tel Hreiz itself was built at “a safe elevation” of three meters above sea level — which would not have felt safe for long.

But it is not only the encroaching water that would have caused havoc on the villagers and their homes. “This rate of sea-level rise means the frequency of destructive storms damaging the village would have risen significantly,” said Galili in the press release.

“The environmental changes would have been noticeable to people, during the lifetime of a settlement across several centuries,” said Galili. “Eventually the accumulating yearly sea level necessitated a human response involving the construction of a coastal protection wall similar to what we’re seeing around the world now.”

In situ antler of Mesopotamian fallow deer, Dama dama mesopotamica. (E. Galili)

According to the researchers, with current estimates predicting that today’s sea level is rising from 1.7 to 3mm per year, modern man can learn from the similar, but more extreme challenges presented to the Neolithic village.

“Modern sea-level rise has already caused lowland coastal erosion around the world. Given the size of coastal populations and settlements, the magnitude of predicted future population displacement differs considerably to the impacts on people during the Neolithic period,” said co-author Dr. Jonathan Benjamin from Flinders University in Australia in a press release.

Storms, hurricanes, tsunamis, oh my!

While seaside property was, and still is, much in demand, life on the coast is often afflicted with “seasonal changes and unexpected, sometimes catastrophic events, including storms, hurricanes, tsunamis, as well as sea-level rise,” write the authors.

(a) isometric modeling of the Tel Hreiz seawall based on an aerial photograph of the site and its hinterland (b) schematic cross section of the site today, and (c) during the Pottery Neolithic period (J. McCarthy, E. Galili, and J. Benjamin)

While most consider tsunamis a natural disaster that largely hits the far east, research looking into the destruction of the famed Caesarea Port found that the booming Roman city and its fabled port were likely fatally damaged in a 115 CE tsunami that was triggered by an earthquake that destroyed Antioch. According to the researchers, this was not the first tsunami on Israel’s shores, nor the last.

With impending doom in mind, the authors look to the past to see how ancient man dealt with its existential existence. “Many of the fundamental human questions and the decision-making relating to human resilience, coastal defense, technological innovation and decisions to ultimately abandon long-standing settlements remain relevant,” said Galili in the press release.

Prior to the abandonment of Tel Hreiz, it appeared to be a thriving village. Since early surveys in the 1960s, underwater archaeologists have discovered paving stones, hearths, potsherds, animal bones from eight species that were presumably used for food (including pig and dog), a variety of flint tools (but no arrowheads), and basalt tools, including a mortar. The site has never been systematically excavated, but a 1997 article discusses what appears to be booming olive oil production at Tel Hreiz, as well as other similar submerged sites off the Carmel Coast.

Later excavations found stone structures such as this seawall in 2012, and upright wooden poles which archaeologists believe served as foundational support for wooden huts. In 2015, a storm removed more debris from the wall and also revealed remains of two 18-20 year old female skeletons buried in clay.

(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).

“Tel Hreiz appears to represent just one of a series of small, sedentary villages that were located along the Mediterranean littoral of northern Israel, and whose inhabitants were engaged in agriculture, pastoralism, hunting as well as fishing,” write the authors.

The artifacts were covered for millennia by a protective layer of sand of a depth of approximately 1-2 meters. They were only recently exposed, by man — through building, and excavation — as well as storms. Because the sea level rose steadily, there was no occupation at the village after it was abandoned and thus the dating of the artifacts is relatively secure.

“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,” said Flinder’s University’s Benjamin.

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