CORONA Satellite Photography and Ancient Road Networks: A Northern Mesopotamian Case Study. (Method)
Ur, Jason, Antiquity
Landscape archaeology has emphasised the role of the entire landscape in ancient life, rather than putting an exclusive focus on those loci of intensive behaviour we call "sites." The broader area of interest requires a corresponding reduction in intensity, the difference between digging a 100 [m.sup.2] trench and surveying a 200 [km.sup.2] region. In order to study entire regions efficiently, landscape archaeologists have normally turned to remote sensing data sources. In the Middle East, aerial photographs have been difficult to obtain, so these sources have generally been limited to low resolution SPOT and LANDSAT imagery, which are sufficient for geomorphological studies but too coarse to detect most archaeological landscape features. Archaeologists working in the Middle East are now beginning to take advantage of a newly available resource, the declassified CORONA satellite program, which combines the large coverage of the modern low resolution satellites with the high resolution of aerial photography. In this case study, I have used CORONA photographs to identify and map ancient road systems in north-eastern Syria (Figure 1).
[FIGURE 1 OMITTED]
Hollow ways, also called linear hollows or sunken lanes, are broad and shallow linear depressions in the landscape, thought to be formed by the continuous passage of human and animal traffic (Taylor 1979, Tsoar & Yekutieli 1993, Wilkinson 1993). They occur on the dry farming plains of northern Mesopotamia and elsewhere in the Middle East, and are generally 60-120 m wide and 0.50-1.5 m deep. In spite of their size, these hollow ways can be difficult to detect on the ground (Figure 2). The largest ones may be visible under certain light conditions and oblique angles, and in the dry season, a slightly thicker scatter of weeds may, mark the position of the trough. From the air, however, hollow ways are immediately visible. In northern Mesopotamia, their visibility can be explained differently in different seasons. In the summer and autumn they are detectable as soil marks because their troughs retain moisture and promote weed growth. In the spring, these moisture-retaining properties encourage denser growth of grass crops, producing distinctive crop marks.
[FIGURE 2 OMITTED]
Hollow ways in northern Mesopotamia were initially studied by Van Liere and Lauffray in the Upper Khabur basin (Van Liere and Lauffray 1954-55, Van Liere 1963). Using low level aerial photographs, they mapped out a basin-wide pattern of small radial systems around Bronze Age tell sites and a second narrower group associated with Byzantine sites. They concluded from these small non-integrated systems that the Bronze Age landscape consisted of systems of economically independent agricultural towns and their satellite-settlements (Van Liere and Lauffray 1954-55: 146).
More recently, T.J. Wilkinson has mapped hollow ways in Syria, south-eastern Turkey, and northern Iraq, based on aerial photography and topographic maps (Wilkinson 1993, Wilkinson and Tucker 1995). Similar radial systems were found, but the tendency for many hollow ways to terminate without connecting with another site led Wilkinson to conclude that these roads also were used for movement to and from fields and pasture, and that animal traffic was also involved in their formation. Furthermore, a small group of interregional hollow ways suggested that these radial systems were more integrated than Van Liere and Lauffray supposed. Finally, the modern site collection methodology applied demonstrated the strong association of these features with sites of the 3rd Millennium BC, although their sporadic use in other periods could not be excluded.
An alternative interpretation has seen hollow ways not as roads but as deliberately excavated channels in order to "harvest" runoff rainfall from the immediate hinterland of 3rd Millennium sites into depressed areas near sites (McClellan and Porter 1995, McClellan et al. …