ABSTRACT
Seismic refraction was used successfully to trace the central feature of the vallum, a substantial ditch parallel with Hadrian’s Wall at Rudchester (Vindobald) (Goulty et al., 1990; Goulty and Hudson, 1994). The ditch was suitably substantial: 8 m (26 ft) wide at the top, with a flat floor 2.5 m (8.2 ft) wide and a depth of 3 m (9.8 ft), cut into sandstones and shales of the Upper Carboniferous Millstone Grit series. The overburden was glacial drift.
