Section 32: quarrying rights to be bounded by vertical planes.

(1) All leases and licences shall be bounded by vertical planes from the surface boundary lines, drawn downwards to the lowest level to which a quarry may extend.
(2) The reference in subsection (1) of this section to the lowest level to which a quarry may extend is a reference to such depth as the Chief Inspector may from time to time define, in writing, as the lowest level to which a quarry may extend.