Satellite images spot early settlements
Telltale signs Archaeologists have used satellite images and a computer program to uncover thousands of ancient human settlements in Syria.
Software developed jointly by Harvard University researcher Professor Jason Ur and Dr Bjoern Menze of the Massachusetts Institute of Technology can identify the remains of homes from the satellite images.
The software examines multiple satellite images, taken over a three-year period, to hone in on discolorations and mounds of soil characteristic of collapsed mud brick houses.
"In the alluvial and largely treeless plains of the northern arc of the Fertile Crescent the primary building material was mud brick," the researchers write.
"As dwellings became dilapidated, their walls were partially dismantled and flattened, and new structures were built atop their remains. The largest mounds still rise to heights of dozens of metres."
The area examined in the project covered about 23,000 square kilometres in what was once known as Northern Mesopotamia. The software identified about 9000 potential archaeological sites, which far exceeds discoveries so far, says Ur.
"I could do this on the ground, but it would probably take me the rest of my life to survey an area this size," says Ur.
The results of the study have been published in the Proceedings of the National Academy of Sciences.
"With these computer science techniques, however, we can immediately come up with an enormous map which is methodologically very interesting, but which also shows the staggering amount of human occupation over the last 7000 or 8000 years," says Ur.
"What's more, anyone who comes back to this area for any future survey would already know where to go," he says.
Dr David Thomas, an archaeologist with La Trobe University in Melbourne, says the research builds on previous work by the late Andrew Sherratt who first purposed the use of satellite imagery to detect ancient settlements.
"It works well on alluvial plains because the tells stand up against the flat surrounding landscape," he says.
Thomas, who has used Google Earth satellite imagery to detect historic sites in war-torn Afghanistan, says satellite imagery is an extremely useful tool for archaeologists.
He says it takes a lot of time and money exploring new sites, so having a guide that shows where to concentrate efforts is of immense benefit.
According to Thomas, the technique can detect tells as low as a few meters. He adds, that previous research also shows it can spot tells that have since been covered by soil.
"The thermal signature of a tell stands out from the surrounding landscape."
According to Thomas, the technique has the potential to detect tells as low as a few meters.
He adds, that this latest work also builds on previous research by Dr Sarah Parcak of the University of Alabama, Birmingham. In 2001, Parcak and colleagues used multispectural and satellite imagery to spot tells in Egypt that had been ploughed out and were no longer visible on the surface to the naked eye.
"Menze and Ur have shown that the combined infrared, chemical, thermal and reflective signatures of even low occupation mounds stand out from the surrounding natural landscape."