This post is a presentation of information on the very interesting discovery of a, 7,000 years old, submerged sea-wall at Tel Hreiz, Israel.
About 7000 years ago, seas were rising all over the world. Ice age glaciers were melting, and the ocean crept up shorelines and toward people’s homes on every inhabited continent. Now, archaeologists have discovered the earliest known defense against those rising seas: a 7000-year-old sea wall built to protect a farming village from worsening storm surges and encroaching saltwater from the Mediterranean Sea. Ultimately, however, the wall failed. It now lies drowned off the coast of Israel, along with the rest of the village it was meant to protect.
“All the different kinds of responses we see toward sea level rise 7000, 8000, 9000 years ago—we’re still seeing all those same responses today,” says Amy Gusick, an archaeologist at the Natural History Museum in Los Angles, California, who studies this period around California’s Channel Islands. They, too, are stopgaps, she notes. “It’s a lesson for us.”
Many drowned ancient villages lie off the northern coast of Israel, which was dotted with farming settlements at the time, says Ehud Galili, an archaeologist at the University of Haifa in Israel. Often they are blanketed by about 1 meter of sand, which helps preserve the ruins but also hides them, until a storm briefly sweeps them clean. “If you are in the right place at the right time, you can see the exposed features,” which look like dark patches in the water, Galili says.
He and his team first discovered the sea wall in 2012, in a submerged settlement called Tel Hreiz that extends as far as 90 meters offshore in up to 4 meters of water.
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.
And now let’s look at some selected parts of the relative publication:
Introduction Coastal environments and their natural resources have attracted human settlement worldwide from as early as ca. 160 ka. Settlement in such environments brings benefits, including access to diverse, temporally and spatially predictable marine and terrestrial resources, but also hazards since these zones are subject to seasonal changes and unexpected, sometimes catastrophic events, including storms, hurricanes, tsunamis, as well as sea-level rise. Settlements immediately adjacent to the sea are most vulnerable and may require rapid as well as sustained human response, such as modification of the natural environment or settlement abandonment. Indeed, past global fluctuations in mean sea level (MSL) are attested by discoveries of submerged ancient settlements worldwide.
Sea levels have changed markedly along the Carmel coast (northern Israel), but the progressive marine transgression and shoreline retreat since 9000 BP is particularly well documented. Between 9000 and 7000 BP, MSL rose ca. 8m (from -16 to -8m), at a mean annual rate of ca. 4mm/year. From 7000 to 4000 BP, MSL rose an additional 8m (from -8m to the present level), at a mean annual rate of ca. 2.6mm/year. From ca. 4000 BP onwards, MSL was relatively stable, with minor changes of less than the local tidal range (±0.30m). Neolithic settlements that were inundated by post-glacial sea-level rise have been discovered along a 20km stretch off the Carmel coast of northern Israel. Before inundation, the sites were rapidly covered by a layer of sand which contributed to their preservation.
The earliest recorded submerged site, Atlit-Yam, is located 200–400m offshore, at a depth of -8 to -12m, and represents a permanent, late Pre-Pottery Neolithic C (PPNC) village dated to 9120 to 8500 BP. Fifteen other inundated settlements date to the more recent late 8th millennium BP and are associated with the late Pottery Neolithic (PN) Wadi Rabah culture, while another site dates to the slightly earlier PN Lodian culture. All PN sites are located 1–200m offshore at depths of 0–5m below MSL.
The submerged Tel Hreiz settlement (34˚56’55″ E, 32˚44’45″ N) was first recognised as an archaeological site in the 1960s, though it has never been systematically excavated. However, since 2012 large sections of this PN (Wadi Rabah cultural phase) settlement were exposed by natural processes, revealing archaeological material extending from the current coastline to a depth of 4m below MSL.
In 2012 and 2015, following winter storms, a long, linear boulder-built feature situated at a depth of 3m on the seaward (western) side of the inundated Tel Hreiz settlement was partially exposed.
The now submerged village was directly associated with this feature, the remains of which we interpret as a seawall. It was deliberately built by the Neolithic villagers and was intended to protect the settlement from waves and marine erosion following post-glacial sea-level rise. The seawall may have worked for a period, however, ultimately it proved futile and the village was eventually abandoned. The Tel Hreiz seawall represents the earliest example of a coastal defence of this type known to date.
(a) Eastern Mediterranean and the Israeli coast; (b) submerged Neolithic settlements off the Carmel coast
Conclusion The Tel Hreiz boulder wall remnant is unique in terms of its location, size, raw material and construction method and does not fit the proportions or form of any other built structure known to date from contemporaneous terrestrial or other submerged Neolithic sites in the region. It does not appear to represent part of a domestic structure, a terrace wall, part of a dam, corral or an edifice associated with freshwater management. Neither is it a settlement or territorial marker.
The numerous unique features relating to the construction of the Tel Hreiz seawall, plus its orientation, size, shape and seaward location relative to the settlement and adjacent to the paleoshoreline, demonstrate that it was unlikely to have been built for another purpose. Moreover, the similarity of finds and evidence of activities inside the settlement as well as adjacent to, and associated with the wall, coupled with the consistency of radiocarbon determinations, all attest to the contemporaneity and association of the wall with the settlement. Finally, the Tel Hreiz seawall closely resembles a later example from the same region, signifying continuity in the practice of building protecting seawalls in coastal settlements of the region over the millennia.
(Source: “A submerged 7000-year-old village and seawall demonstrate earliest known coastal defence against sea-level rise”, by Ehud Galili et al., 2019)
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