Armchair archaeology

tauringhuang.

Sep 4th 2008
From The Economist print edition

Computing: Archaeologists are using free satellite imagery from Google Earth to make discoveries, develop theories and plan expeditions

Google EarthINDIANA JONES, it is fair to say, would not approve. A small band of archaeologists are using Google Earth to make discoveries without getting their hands dirty. Although archaeologists have used satellite imagery for decades, the technique remained out of reach of most researchers because of the prohibitive costs and specialist skills needed to rectify distortions in raw satellite images caused by the angle of capture. But Google Earth, a free program that can be downloaded from the internet giant’s website, makes high-quality satellite images of much of the world’s surface available to anyone with a broadband connection. Archaeologists are now embracing the technology.

David Thomas, a graduate student at La Trobe University in Melbourne, Australia, belongs to a team that launched a project called Archaeological Sites of Afghanistan in Google Earth (ASAGE) last year after plans for a survey near the Minaret of Jam had to be abandoned because of the continuing conflict in the region. He and his colleagues decided that making discoveries using computer mice, rather than shovels and trowels, would have to do instead.

“Realistically it is not possible for a Western field archaeologist to work in that area, and I can’t imagine it will be for the next 20 years,” says Mr Thomas. But, he says, studying images from Google Earth (pictured) “has the potential to enrich significantly our knowledge of Afghanistan’s archaeological remains, particularly in areas that are too large, dangerous or remote to survey from the ground.”

One aspect of the ASAGE project involved the use of high-resolution satellite images to catalogue the details of 463 previously unknown sites in the Registan desert, including mounds known as tepes (the remains of ancient settlements), hand-dug water channels and abandoned dams and reservoirs.

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Little is known about the ancient history of the region, but nearby river valleys have been occupied for centuries, if not millennia. The Ghaznavids, who ruled over a large central Asian empire between the late 10th and 12th centuries, built intricate irrigation systems and established palaces, mosques and walled gardens at their winter capital of Bust and the surrounding settlements of Lashkari Bazar, on the east bank of the Helmand river.

Mr Thomas’s team, who displayed their results at the World Archaeological Congress in Dublin in July, produced plans of sites such as the medieval Islamic fort of Qal’a-i Hauz, believed to be a winter dwelling used by the Ghaznavid elite. The satellite images show evidence of structures that may have been hides used to hunt gazelle, and raised features that were probably used to manage water supplies. Basic plans of Bust were produced by French archaeologists in the 1970s, but the ASAGE researchers have compiled a more detailed plan showing the positions of residences, canals and walled gardens. They hope that providing details of their findings to Afghan archaeologists will enable them to protect some of the sites.

Although Google Earth can help make discoveries remotely in this way, other archaeologists are using it in the planning stages of their work, to identify places that warrant further investigation on the ground. Nico Tripcevich of the University of California, Berkeley, used the software to help with his research into the quarrying and trade of obsidian, a kind of volcanic rock used by pre-Hispanic peoples to make tools, weapons and decorative objects as early as 10,000 years ago. He used Google Earth to find tracks used to carry the rock, probably in llama caravans, away from a quarry site at Colca Canyon, at an altitude of 4,600 metres, in southern Peru. Linear features, such as Inca walls and roads, are easy to spot because they cut across natural features.

Mapping these routes has helped archaeologists reconstruct production and trade patterns, and hence economic, social and political relations in the region in the thousands of years before Europeans arrived. “Working at high altitude is exhausting, and you want to have a good idea of where you’re going to go before you set out,” says Dr Tripcevich. “Google Earth helps you make a short list of places to investigate.”

Jason Ur, an anthropologist at Harvard University, is using the software as part of his investigation of Tell Brak, a site in north-east Syria. It was one of the largest urban sites in northern Mesopotamia and is believed to have been settled as early as 6,000 BC. Dr Ur is using Google Earth to identify tracks and other linear features running away from Tell Brak, as part of his research into the mechanism of Mesopotamian city-formation.

“Google Earth gives you free access to imagery that would otherwise cost a fortune, and require specialist training to make use of,” says Dr Ur. And being able to pan and zoom the satellite images quickly makes it much easier to spot archaeological features and relate them to each other. “If you were to press your nose against an Impressionist painting, you would see colour and maybe elements of form, but it’s not until you pull back that these would turn into a bridge or water lilies,” he says.

But Dr Ur and others are aware that there could also be a dark side to Google Earth’s archaeological potential: looters could also use the software to find promising targets. “We cannot assume that all users who seek out archaeological sites are doing so out of a positive interest in antiquity,” says Dr Ur. So archaeologists should be careful about giving out precise co-ordinates, he says. “In the cases of unexcavated sites, the archaeologist’s mission might be to give the public a general idea of the extent of ancient settlement, without handing out a road-map that could be abused by looters.”