Any old archaeologist can find ancient cities by looking for evidence of buildings etc, but it takes a next level Indiana Jones to use satellites. A group of archaeologists are doing just that, finding “14,000 settlement sites spanning eight millennia in 23,000 square kilometres of northeastern Syria”.
The satellite-based method relies on the fact that human activity leaves a distinctive signature on the soil, called anthrosols. Formed from organic waste and decayed mud-brick architecture, anthrosols are imbued with higher levels of organic matter and have a finer texture and lighter appearance than undisturbed soil — resulting in reflective properties that can be seen by satellites.
Menze trained software to detect the characteristic wavelengths of known anthrosols in images spanning 50 years of seasonal differences. This automation was key. “You could do this with the naked eye using Google Earth to look for sites, but this method takes the subjectivity out of it by defining spectral characteristics that bounce off of archaeological sites,” says Ur.