O.G.S. Crawford, founder of ANTIQUITY, flew in the 1920s over an English landscape where the grooves and lines cut into unploughed downlands showed the courses of roads and tracks since earliest times. Similar patterns of crop- and soil-marks in the rain-fed agricultural zone of the Middle East, when studied in the same spirit, also reveal the local and the long-distance routes of a proven great age.
Expansion and intensification of archaeological surveys during recent years has opened up the entire landscape for investigation. To complement the myopic focus upon settlement sites, techniques of off-site archaeology have started to unveil traces of past land-use systems, water supply, communications, quarrying and other landscape features. Such studies are not new, for they were pioneered, as field archaeology, earlier this century especially when aerial archaeology was developing as a key archaeological tool (Beazeley 1919; Crawford 1923; 1953). Today, air photographs and satellite images are even more valuable, partly because techniques of off-site archaeology and survey supply more detailed ground data to act as control for remote sensing studies. Features once interpreted by assumption or on rather flimsy evidence can now be examined critically.
The features here entitled 'linear hollows' are particularly evident over thousands of sq. km of the dry farming zone of the Jazira of northern Syria and Iraq. In a classic paper Van Liere & Lauffray (1954) described, mapped and interpreted these features as ancient routes hollowed out of the landscape by the sustained passage of humans and animals (similar observations in Crawford 1953: 8; Buringh 1960: 212-13; Oates 1968: plate 1a; Oates & Oates 1990: plate 66). Related features in the British countryside, sometimes found along existing roads, have long been called 'sunken lanes' or 'hollow ways' (Taylor 1979; Hindle 1982: 11). Other studies have indicated a relationship between similar hollow way routes and prehistoric funerary monuments in the Netherlands (Jager 1985), and an impressive complex of linear concave roads, dating to 900-1150 AD, has been recorded around Chaco Canyon, New Mexico (Obernauf 1980; Powers 1984: 52-3; Gabriel 1991; Warburton & Graves 1992: 57).
As roads, the Jazira features are fundamental to the ancient geography of this region which can then be divided into settlement sites (tells and other sites); systems of intensive land-use and manuring (represented by some off-site artefact scatters: Wilkinson 1989); and communications (the linear hollows). This paper describes linear hollows, suggests mechanisms of formation and discusses alternative interpretations that have been proposed. Specifically, it has recently been suggested that such features in the Jazira may have been canals, or at least conduits for channelling run-off to fields to enhance soil moisture in this marginal environment (McClellan n.d.). As will be shown below, such a conclusion is unwarranted, given the relationship of the features to topography as well as the absence of cut channels, upcast or clean-out silts.
The Jazira and the selected case studies
The undulating plateau of the Jazira, developed on Tertiary sedimentary formations, generally fluctuates between 300 and 450 m above sea level, except where broken by upstanding anticlinal hill masses such as the Jebels Abd al-Aziz and Simjar (FIGURE 1). The name Jazira (Arabic: island) derives from its position between the Tigris and Euphrates rivers. Today its landscape is a highly degraded steppe (Bottema 1989). The northern part receives sufficient rainfall for crops of cereals and legumes in most years; where rainfall is less than about 250 mm per annum, crops fail too frequently to be economic. The zone of potential dry-farming has fluctuated with social, political and environmental conditions. When political control was weak during the late Ottoman period, the limit of cultivation was in the moister northern steppe; during the 20th century, with more political control and investment, settlement and cultivation spread to an extreme southern limit close to the 200-mm isohyet (FIGURE 1) where farming is very risky (Lewis 1955). …