Ancient Saudi ‘lava tubes’ inhabited thousands of years ago uncovered

A major archaeological investigation has, for the first time, excavated a lava tube in Saudi Arabia that was inhabited by humans up to 10,000 years ago.

The site at Umm Jirsan shows evidence of human activity spanning several thousand years from the Neolithic period to the Bronze Age.

Supported by Saudi authorities, it continues decades of research undertaken in the region to piece together the ancient history of human activity in the Middle East.

The excavation confirms the presence of humans within the unique geological formation, effectively created by lava flows that harden on the surface but hollow out to create a long, inhabitable conduit made from hardened rock.

Animal remains, human-made earthenware and rock art are among the evidence of human occupation retrieved.

It’s the first time such a geological formation has been studied in detail by an archaeological team in the region.

“We’d read some reports by the Saudi Geological Survey, about various caves and lava tubes – they had been recording them and mapping them – and based on some of these reports, we thought we’d go check some out,” says Queensland’s Griffith University Dr Mathew Stewart, the lead author of the study and a research fellow at the Australian Research Centre for Human Evolution.

“There are hundreds of 1000s of fossils in these sites, mostly seem to be dating to the Holocene. This is in a landscape where this sort of material doesn’t tend to survive on the surface, the Holocene fossil record in Arabia is very poor,” Stewart says.

“When we were down there we discovered scatters of lithic artifacts, pottery, ostrich eggshell, various structures within the lava tube and the surrounding area, rock art, and because of this, we decided to conduct an excavation as well.”

People excavating a site inside a cave
Excavation at Umm Jirsan. Credit: Green Arabia Project, supplied

A pastoral history of Saudi site

Excavating the site enabled an understanding of the tube’s use. They speculate that it served as a key checkpoint between two oases, where pastoralists would have moved with their livestock, most of which were grazing along such routes. Among animal remains were those of ancient horses, cattle, gazelles, goats and other hooved animals.

In addition, these long routes were likely used for burials. ‘Pendant tombs’ were identified radiating out from the oases, suggesting these routes were important social, economic and cultural “lifeways” for Saudi’s ancient pastoralist societies.

Umm Jirsan itself is located in a volcanic region of Arabia and extends 1.4km in length. Inside the walls of the tube is evidence of rock wall art, mostly consisting of sheep representations, along with ibex, goats and cattle, usually associated with representations of humans herding these animals.

A cave entrance
Entrance to Umm Jirsan Cave. Credit: Green Arabia Project, supplied

“People certainly did occupy these throughout the Neolithic, and at various points,” Stewart tells Cosmos.

“We put forth this hypothesis that this is … perhaps our sort of stopping off point on these pastoral migration routes.

“I think the other significance is that Saudi Arabia is putting a lot of effort and a lot of money into the archaeological research, in particular, of Umm Jirsan, and this has focused on a lot of stone structures and surveys in the landscape.

“Umm Jirsan, lava tubes, caves in general hold huge potential in an arid area, like Arabia, to fill in a lot of these gaps that we have in both the fossil record and the archaeological record.”

The research was published in the journal PLOS One.

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