se a ▁c aves ). ▁Therefore , ▁the ▁distribution ▁of ▁lim estone , ▁mar ble ▁( met am orph osed ▁lim estone ) ▁and ▁vol cano es ▁defines ▁the ▁location ▁of ▁c aves ▁in ▁in land ▁New ▁Zealand . ▁The ▁main ▁regions ▁of ▁kar st ▁top ography ▁are ▁the ▁Wait omo ▁District ▁and ▁Tak aka ▁Hill ▁in ▁the ▁Tas man ▁district . ▁Other ▁notable ▁locations ▁are ▁on ▁the ▁West ▁Coast ▁( P un aka iki ), ▁the ▁Haw kes ▁Bay ▁and ▁F i ord land . ▁ ▁L ava ▁c aves ▁( lava ▁tub es ) ▁usually ▁form ▁in ▁p ā ho e ho e ▁la va ▁flows , ▁which ▁are ▁less ▁vis cus ▁and ▁typical ▁formed ▁from ▁bas alt . ▁When ▁an ▁er u ption ▁occurs ▁the ▁outer ▁layer ▁of ▁the ▁la va ▁flow ▁hard ens , ▁while ▁the ▁interior ▁remain ▁liquid . ▁The ▁liquid ▁la va ▁flows ▁out ▁as ▁it ▁is ▁ins ulated ▁by ▁the ▁hard ened ▁cr ust ▁above . ▁These ▁c aves ▁are ▁found ▁where ▁there ▁are ▁relatively ▁recent ▁bas alt ic ▁vol cano es ▁in ▁New ▁Zealand , ▁such ▁as ▁the ▁A uck land ▁Vol can ic ▁Field ▁particularly ▁on ▁Rang it oto , ▁Mount ▁E den ▁and ▁Mat uk ut ur uru . ▁ ▁The ▁distribution ▁of ▁sea ▁c aves ▁is ▁more ▁sp or adic , ▁with ▁their ▁location ▁and ▁orientation ▁being ▁controlled ▁by ▁weak ness ▁in ▁the ▁underlying ▁rock . ▁As ▁cave ▁systems ▁take ▁many ▁thousands ▁of ▁years ▁to ▁develop ▁they ▁can ▁now ▁be ▁isolated ▁from