Rediscovering the first cities
An AHRC-funded project has been using satellite imagery to trace the evolution of the world’s first cities.
It sounds like the ingredients of a Hollywood blockbuster: Central Intelligence Agency (CIA) satellite images declassified by presidential order; spy satellites firing film canisters to earth; journeys of discovery through the cradle of civilisation.
This, in fact, is The Fragile Crescent, an AHRC-funded archaeological investigation into the rise and fall of early settlements in Upper Mesopotamia and the northern Levant, based at Durham University. Bringing together technology old and new with decades of fieldwork, the project has resulted in a treasure trove of information, with far-reaching implications for our understanding of cities and urbanism past, present and future.
In its simplest level, the project involved re-analysing existing archaeological surveys in the light of data gleaned from satellite imagery. This is a twist on usual practice. “Normally, you’d look at the satellite images and then go into the field to do an archaeological survey. That isn’t possible here due to the current conflict,” explains Professor Tony Wilkinson, a principal investigator on the project.
Most of the surveys used are the result of a combined fifty years of fieldwork in the region by Professor Wilkinson and co-principal investigator Professor Graham Philip. “Tony carried out extensive surveys in parts of Northern Iraq, north-eastern Syria and south-eastern Turkey through the 1980s and 1990s,” says Professor Philip. “We took his ground data, my data from Western Syria, and information from several other reliable published surveys, and we worked through it all, checking everything against the satellite imagery. We’d been doing the same thing in parallel for many years; now, thanks to the project, we combined our efforts.”
The satellite data came from the Corona programme, run by the CIA from the late 1950s to early 1970s. This comprised a series of reconnaissance satellites orbiting the earth to carry out surveillance of strategic areas.
“The images were shot onto film by moving cameras mounted on the satellites and fired out in steel canisters with parachutes; real Dr Strangelove stuff!” says Professor Philip. These canisters were recovered by low-flying planes, and the negatives were developed and printed. US military interpreters viewed the resulting strips of film on stereoscopes; by the time then-US President Bill Clinton signed an Executive Order to declassify the Corona images in the mid-1990s, advances in technology made the process of analysis much easier. The Fragile Crescent researchers were able to examine the satellite data on computers with the help of high-resolution scanners and image processing software.
What’s particularly notable about these images is their high resolution, allowing archaeologists to see key details in the landscape as little as two metres across in size. “You can practically pick out every cairn and field boundary wall,” reveals Professor Philip. “The archaeological sites also stand out from background soils because they’re a slightly different shade of grey on the images, so you can pick up concentrations of ancient settlement debris.”
The Corona imagery allowed the project to operate on a vast scale, essentially filling in gaps between sites already discovered through fieldwork.
“Most field surveys look at areas of a few square kilometres, at most several tens of square kilometres,” explains Dr Dan Lawrence, a former PhD student on the project. “We were looking at an area that’s roughly the size of the British Isles. Instead of looking at one city, we could look at twenty.” What’s more, Dr Lawrence says, this kind of data has increasing importance due to the conflict in the region: “There’s a whole generation of researchers who have come on the scene since the Syria conflict began who’ve can’t travel there now and may not be able to for a long time, but they can still engage with the area through the satellite imagery. Of course, it’s a huge advantage when analysing the images if you’ve been there and know what it should look like on the ground. But at least younger scholars can still be involved even though they can’t do the fieldwork at the moment.”
Once the data was collated, the team were able to start their analysis: modelling populations, and comparing settlement sizes across different regions and landscape types. “Some of our findings have changed our whole conception of the area,” says Professor Wilkinson. “For example, we have a completely different understanding of the pathways to urbanism in the third and fourth millennia. What we can see now is that third millennium cities show what we call ‘pulsating urbanism’ – they’re there for a few hundred years then disappear again, unlike in the fourth millennium, which was about cities growing slowly. We also learnt more about sustainability: the smaller sites tended to exist for thousands of years, whereas the big ones were often flashes in the pan. We didn’t expect this.”
The findings have implications for contemporary urbanisation. “People call Syria and Iraq the ‘cradle of civilisation’ for a reason: you get the first cities on the planet there; this is where it all starts,” says Dr Lawrence. “The next step of the project is relating the processes we’ve uncovered to factors like climate change and city size and resilience, which are relevant to modern cities and how we think about the sustainability of city growth in the present day.” What’s more, the data has benefited other academic areas. “A fantastic amount of work has been done on textiles in the last ten years, but it was never put together with the landscape evidence,” explains Professor Wilkinson. “We’ve linked these two bodies of research, finding that it was the sheep-grazing and woollen textile industry that fuelled the growth of settlements in dry soil of the steppe.”
There’s also the hope that this ground-breaking research will contribute to the preservation of archaeological sites and monuments in the region, potentially through the creation of a comprehensive sites and monuments record for post-conflict Syria, that is being developed in collaboration with French colleagues and UNESCO. After all, the landscape has changed almost beyond recognition since Professor Wilkinson began his work there in 1972. “When I envisaged the Fragile Crescent project, it was a play on words with a number of elements: fragile climatically and environmentally but fragile also because of the human processes that are destroying it, both in conflict and in peacetime.”
Banner image credit: Detail of Corona image of the Homs basalts in western Syria. Corona Mission: USGS gratefully acknowledged; image from the Homs Project, courtesy of Graham Philip).