Archaeologists from Historic England spent the day digging test trenches to try and establish the width and depth of the original and subsequent cuttings. We imagined hitting solid chalk within a few inches but this was not the case. The results were not as clear as hoped but seemed to show that the original cut was wide (over a metre) but relatively shallow. A subsequent cut at a later stage was much narrower (less than half the original width) but much deeper. Archive photo’s support this theory…
The Map of Australia 