▁a ▁narrow ▁sh aft , ▁the ▁min ers ▁used ▁up ▁as ▁little ▁ ▁of ▁the ▁product ive ▁agricult ural ▁land ▁as ▁possible . ▁He ▁suggested ▁various ▁other ▁practical ▁issues ▁which ▁supported ▁his ▁ideas ▁including ▁that ▁open ▁cast ▁ch alk ▁extra ction ▁would ▁require ▁moving ▁the ▁material ▁further ▁than ▁necessary ▁and ▁that ▁shall ower ▁ch alk ▁depos its ▁have ▁much ▁of ▁their ▁minor ▁min eral ▁content ▁le ached ▁out ▁by ▁ground water . ▁ ▁Another ▁theory ▁that ▁has ▁been ▁advanced ▁is ▁that ▁the ▁exc av ations ▁were ▁made ▁in ▁order ▁to ▁get ▁fl ints ▁for ▁implements . ▁ ▁Further ▁reading ▁ ▁F . C . J . ▁Sp ur rell ' s ▁paper ▁" D ene hol es ▁and ▁Art ific ial ▁C aves ▁with ▁Vert ical ▁En tr ances ", ▁published ▁in ▁the ▁Arch ae ological ▁Journal ▁for ▁ 1 8 8 1 ▁and ▁ 1 8 8 2 . ▁" D ene hol es " ▁Harry ▁Pear man ▁( 1 9 6 6 ) ▁Ch else a ▁Sp ela e ological ▁Society ▁Records ▁Vol . ▁ 4 ▁ 7 2 pp ▁ ▁Dor othy ▁L . ▁Say ers , ▁The ▁N ine ▁T ail ors , ▁ 1 9 3 4 . ▁ ▁( Body ▁found ▁in ▁a ▁den e hole .) ▁ ▁External ▁links ▁ ▁Kent ▁Under ground ▁Research ▁Group ▁page ▁on ▁den e hol es ▁ ▁Rain ham ▁Kent ▁D ene ▁H ole ▁Ph otos ▁from ▁ 1 9 8 0 s ▁ ▁Col lapse ▁of ▁D ene hole ▁in