Over the last couple of days we have finally removed the remains of the seating bank deposits to amphitheatre 1A, and have now exposed the pre-Roman ground surface over nearly the entire excavation trench. This has allowed us to see what sort of evidence has survived on the site from the period immediately before the Romans began to build the first amphitheatre at Chester. The find of the footprints in the south-western corner of the excavation has already been mentioned, and very close to these were a line of timber post-settings which might indicate a fence line associated with a stock enclosure.
However, at the northern end of the trench we have now uncovered a series of narrow, parallel ridges that clearly pre-date the outer wall of the first amphitheatre. This type of earthwork is known as ‘cord rigg’ and has been identified on upland areas like the Cheviots of Northumberland and on excavations beneath Roman forts on Hadrian’s Wall. It usually comprises a series of narrow ridges less than a metre apart, formed as the result of cultivation and it is generally considered to date to the late pre-Roman Iron Age. So we are getting an emerging picture of a pre-Roman arable agricultural regime with an associated field system that has hitherto been very elusive in the Chester area.
An article by Tim Gates in British Archaeology issue no. 49, for November 1999 offered the following observations on the dating of cord rigg:
Patches of ‘cord rigg’ have been identified at more than 70 different locations within the survey territory around Hadrian's Wall, and the size of separate plots can be anything from that of a small allotment to something larger than a football pitch. Its date has been suggested by a number of instances where late Iron Age or Roman period contexts have been established by excavation or field survey. For example, narrow-ridged soil surfaces have been found beneath the Hadrianic levels of several forts along the Wall. At Denton, west of Newcastle, a field of cord rigg was found to have been under cultivation right up to the point where the land was appropriated by the Roman army in order to build the Vallum in about AD130.
Since this form of cultivation seems to have required nothing very sophisticated in the way of tools, it would be no surprise if it proved to have a long prehistoric ancestry. Certainly, a strong case exists for its widespread use by native farmers in the later Iron Age and Roman periods not only in Northumberland but also in parts of southern Scotland. The evidence derives largely from air photographs which record many instances of cord rigg close to stone-built settlements similar to the ones described above.