Table 1.1.

Summary log of the borehole that encountered the interpreted glaciotectonic raft

Depth below seabed (m)FormationGeotechnical description
32–39Swarte Bank FormationHard grey sandy gravelly CLAY. Gravel is fine to medium, mainly of chalk
39–46ChalkVery weak to weak low-density white CHALK (CIRIA* Grade B2) (interpreted as raft of chalk)
46–55Swarte Bank FormationVery stiff grey slightly silty CLAY
55–73 (end of borehole)ChalkVery weak low-density white to light-grey CHALK (CIRIA Grade Dm) (interpreted as in situ chalk)
  • Note that the strata above the Swarte Bank Formation have not been detailed for brevity (Lord et al. 2002).