▁an ▁u pr ight ▁position ▁could ▁be ▁maintained . ▁ ▁History ▁ ▁Pl iny ▁the ▁E lder ▁wrote ▁about ▁British ▁ch alk ▁extra ction ▁in ▁A . D . ▁ 7 0 ▁and ▁arch ae ological ▁evidence ▁shows ▁that ▁at ▁least ▁some ▁of ▁the ▁den e hol es ▁were ▁being ▁explo ited ▁during ▁pre history . ▁Cast s ▁taken ▁of ▁some ▁of ▁the ▁pick - hol es ▁near ▁the ▁roof ▁show ▁that , ▁in ▁all ▁probability , ▁they ▁were ▁made ▁by ▁b one ▁or ▁horn ▁pick s . ▁N umer ous ▁b one ▁pick s ▁have ▁been ▁discovered ▁in ▁Es sex ▁and ▁Kent . ▁These ▁pick - hol es ▁are ▁amongst ▁the ▁most ▁valuable ▁data ▁for ▁the ▁study ▁of ▁den e hol es , ▁and ▁have ▁assist ed ▁in ▁fixing ▁the ▁date ▁of ▁their ▁formation ▁to ▁pre - R oman ▁times . ▁However , ▁very ▁few ▁artifact s ▁which ▁would ▁provide ▁d ating ▁evidence ▁or ▁assist ed ▁in ▁determ ining ▁the ▁uses ▁of ▁these ▁pre histor ic ▁exc av ations ▁have ▁been ▁discovered ▁in ▁any ▁of ▁the ▁known ▁den e hol es . ▁Chr ét ien ▁de ▁Tro yes ▁has ▁a ▁passage ▁on ▁c aves ▁in ▁Britain ▁which ▁may ▁have ▁reference ▁to ▁den e hol es , ▁and ▁tradition ▁of ▁the ▁ 1 4 th ▁century ▁treated ▁the ▁den e hol es ▁of ▁Gray s ▁as ▁the ▁f abled ▁gold ▁mines ▁of ▁C un ob eline ▁( or ▁C ym b eline ) ▁of ▁the ▁ 1 st ▁century . ▁ ▁In ▁