Hidden beneath mounds of Earth, in the fertile crescent of the Middle East, lie overlooked networks of small settlements that date back millennia. Archaeologists are now probing these mounds to find out more about early human settlements.
Satellite photos were combined with modern multi-spectral images and digital maps of the Earth’s surface to create a new method to map large-scale patterns of human settlement. 14,000 settlements were mapped, spanning eight millennia, in 23,000 square kilometers of northeastern Syria. The researchers published their findings in the journal Proceedings of the National Academy of Sciences.
Traditionally, archeology targets the biggest features, like palaces or cities, but tends to ignore smaller settlements. It’s hoped that such a comprehensive map will uncover long-term trends in urban activity.
The new method relies on the fact that all human activity leaves a distinctive signature on the soil. This is called anthrosols, and it’s formed form organic waste and decayed mud-brick architecture. Anthrosols with higher levels of organic matter leave a finer texture behind on undisturbed soil, which results in a reflective property that can be detected by satellites.
Software was developed to automate the process, the larger the mounds of earth, the longer the older the settlement.
The method has already renewed speculation about the importance of water to the development of cities. The study has found that a number of sites are larger than expected given the fact that they aren’t located near rivers or in areas of high precipitation. The Tell Brak settlement is an example of such a site. Archeologists believe that irrigation might be an after-effect of urbanization.
Reference: “Mapping patterns of long-term settlement in Northern Mesopotamia at a large scale” by Bjoern H. Menze and Jason A. Ur, 19 March 2012, Proceedings of the National Academy of Sciences.