Archaeology from Above

The remnants of ancient cultures are often hidden by more than dirt. What isn’t eventually reclaimed by forests and jungles can be hidden by urban development. Technologies originally developed for other purposes, however, are being harnessed to survey large parts of the planet for science, and their effect on archaeology has been particularly dramatic. . .

Egypt may top most archaeological A-lists but Sarah Parcak, of the University of Arkansas, has shown that there’s still a lot left to excavate. She used satellite imagery to locate 17 new pyramids, 1000 tombs, and 3,100 ancient settlements without setting foot in Egypt’s sands.

Afghanistan isn’t a healthy place for hiking, especially for Westerners, so David Thomas, of La Trobe University in Melbourne, Australia used Google Earth to locate over 670 new archaeological sites in Afghanistan’s Registan Desert without leaving his lab.

The rich archaeological heritage of Peru is coming under threat from expanding population. Science teams are therefore trying to locate and document the country’s ancient sites quickly, before development covers them forever. Their technology of choice? Portable drones.

Today, archaeology is as much digital as digging. Indiana Jones will always have a shovel, but in the twenty-first century he (or she) will also have a laptop, serious computer skills, and “eyes in the sky.”

MTI satellite (NASA)

MTI satellite (NASA)

Sensing from space
Satellites can image most of the earth’s surface from orbit, but their biggest value to science is their sensors. High resolution cameras, for example, can identify objects as small as two feet (0.6 m) in diameter – fine enough to find for the smallest human structures. Infrared sensors use heat differences between materials to detect patterns, such as ancient croplands, invisible to the human eye. And ground penetrating radars detect differences in material densities to find bricks, walls, and roads.

Sophisticated sensing, however, demands sophisticated interpretation. Dr. Parcak, for example, has made satellite archaeology her specialty and has put in the countless hours of study necessary to make this tool effective. That training has paid off with a wealth of new site discoveries. Other scientists have taken an alternate route – Google Earth.

It didn’t take long for archaeologists, such as Dr. Thomas, to realize the potential of Google Earth images for streamlining much of their work. A desktop software tool is all that’s required to quickly and economically access a massive volume of photographic data. Large repositories of Google Earth images make possible both efficient discovery and effective site protection. Dated images provide a baseline for the condition of a site so that any later changes can reveal unambiguous evidence of looting.

The wide availability of Google Earth is even bringing archaeology to “citizen science.” Amateurs can now study images and make discoveries of their own.

Closer to the ground
Unmanned aerial vehicles (UAVs), or drones, are a more recent addition to the archaeology toolbox. The drones used for science are a far cry from the military vehicles reported in the news. Companies that make them are finding a healthy business in marketing smaller systems, and their falling prices put them in reach of even modest academic budgets. Many are compact enough to carry into remote places to cover limited areas quickly. For many needs, they offer more flexibility than satellites or Google Earth.

Where survey time deadlines are tight, as they are in Peru, the flexibility of drones is essential. These machines are used to inform government and science policy in the context of builders, miners, and squatters.

Practical impact
Satellites, drones, and aircraft are more than tools for archaeology; they’re at the core of how the science gets done. These technologies are

  • Effective. Sensors detect hints of human activity that would likely be missed from the ground. Such surveys can also identify the full extent of some sites(such as Angkor) that might otherwise go undiscovered
  • Economical. It’s costly and time-consuming to find potential excavation sites from the ground. Use of these  technologies can yield enormous savings that can make follow-up digging possible
  • Fast. Surveys that used to take months or years can now be completed in days or weeks, smoothing the often-contentious relationships between science, government, and development interests
  • Safe. Unfortunately, many of the most interesting archaeological sites today are in dangerous places

An additional advantage shared by all of these imaging technologies is that they’re nondestructive; archaeologists don’t have to dig into the earth to make major new discoveries, which changes what is achievable when areas are inaccessible or hostile. Physical incursion, however, is different from social incursion; at the very least, scientists are still looking at things without permission and some people have an issue with this, as the folks at Google Earth found out. The ethical standards of the archaeology profession, however, are adapting to address such issues, acknowledging that these capabilities are here to stay.

Space borne and airborne sensing require new skill sets for their effective use. Software programming, imagery analysis, and database processing are now integral to studying the past, which means that archaeologists must either possess these skills or collaborate with others who do. Collaboration, of course, only expands the range of perspectives that can contribute to a problem, enabling more complete, nuanced interpretations of archaeological data. Archaeology is a more productive science because of these technologies. And there’s plenty left out there to find.

 

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