These units first appear on the 1987 OS and probably represent the reclamation of the Nunnery Colliery site. Nunnery Colliery was active from 1868 to 1953. SMR record 00248 nearby records possible postmedieval bell pits in this area before obliteration by later slag heaps. This area was considered to be just outside the park boundary by Scurfield (1986).