Flint mines are within the western part of the iron age hillfort and also outside the fort on the southern side of the hill Over 100 shafts are visible as depressions measuring up to 6 metres in diameter and 3 metres deep. Excavated shafts were up to 12 metres deep. 6 seams worked, radiocarbon dated to 2750BC
ref. "Prehistoric Flint Mines" (Shire Archaeology) by Robin Holgate (1991)
Detailed account of the site here - http://www.sussexarch.org.uk/saaf/cissbury.html />