With the help of Google Earth, researchers examining the deserts of Saudi Arabia have found around 400 unreported stone structures in the Arabian Desert, likely built by nomadic tribes thousands of years ago.
As Owen Jarus at Live Science reports, the structures are called “gates” since, from an aerial view at least, they share a likeness with field gates. Most of them were found in clusters in Harrat Khaybar, a region in west-central Saudia Arabia known for its now-extinct volcanic domes. The researchers aren’t sure exactly how old the structures are or what their purpose may have been. The research appears in the November issue of Arabian Archaeology and Epigraphy.
“We tend to think of Saudi Arabia as desert, but in practice there’s a huge archaeological treasure trove out there and it needs to be identified and mapped,” David Kennedy, an archaeologist at the University of Western Australia, tells Nicholas St. Fleur at The New York Times. “You can’t see them very well from the ground level, but once you get up a few hundred feet, or with a satellite even higher, they stand out beautifully.”
The structures were first observed in person back in 2004 by neurologist Abdullah Al-Saeed, who leads a group of amateur archaeologists in Saudi Arabia. At that time, he and his colleagues found three-foot-high stone walls among Harrat Khaybar’s lava domes, but it wasn’t until 2008, when Al-Saeed looked at the area with Google Earth that he realized the extent of the stone structures, St. Fleur reports. Once again, he and his colleagues made the trek to the remote place. This time, they sent their photos to professional archaeologists like Kennedy for some insight.
Kennedy was intrigued by the pictures. According to a press release, he has spent almost 40 years working on archaeology in the Arabian Peninsula. In 1997, he began aerial surveys of lava fields in Jordan, documenting stone structures including kites, which were a type of animal trap, funeral monuments and wheels of an unknown purpose.
Kennedy signed on to help, and over the course of a decade, the archaeologist began searching for and documenting the gates including one that is 1,600 feet long, using Google Earth.
“We would have loved to fly across into Saudi Arabia to take images. But you never get the permission,” Kennedy tells St. Fleur. Instead, he relied on the search engine's satellite program. He's found many structures since, but the gates, he says, are unique. “They don't look like structures where people would have lived nor do they look like animal traps or for disposing of dead bodies,” he says. “It’s a mystery as to what their purpose would have been.”
Jarus reports that the gates appear to be the oldest stone structures on the landscape, and may date as far back as 7,000 years. Some of the area’s lava flows also cover some of the gates, meaning the structures are older than some of the lava domes in the area.
It’s possible that in the past the area wasn’t quite as inhospitable as it is today. In fact, in recent years researchers have found evidence for “Green Arabia” a theory that the area has swung between wet and dry periods for over a million years. “The lava fields are often rich in archaeological remains, implying a moister past and more abundant vegetation, and recent fieldwork identifying larger settlement sites supports this notion,” Kennedy writes in the paper. “As in the much better explored lava field of Jordan there are many thousands of stone-built structures which are collectively known to Bedouin as the ‘works of the old men’.”
To learn more about the gate structures, archaeologists will need to travel to the area to survey the walls and try to date the lava flows and look for any artifacts associated with them. This find, along with 2,000 tombs found by Kennedy in 2011, is shedding new light on human habitation in the Arabian deserts. “There are many other features that have only recently been understood as forming classes of prehistoric ‘geoglyphs’ that were widespread in an area thought to be very barren and devoid of human impact,” Stephan Kempe, a retired professor of physical geology at Technische Universität Darmstadt, tells St. Fleur.
And there’s more to be found. Kennedy invites armchair adventurers to help identify more objects by scouring the area on Google Earth for themselves.