The workings of an extensive opencast mine are visible on air photos. Extraction was underway by 1947 and continued for several decades, though not all areas were open at once and exhausted pits were reinstated. The maximum visible extent of these workings have been recorded from the air photos. However it is possible that some areas were mined and then reinstated in the gaps between photographic surveys and these may not have been identified on the subsequent imagery. In so far as these are known, these workings impacted an area of more than 300 hectares. A line of at least 4 small pits between NZ24700 80810 and NZ24820 81330 that are visible on some of the pre-opencast photos are more likely to be test pits or boreholes in preparation of this activity that the remains of post medieval coal pits, these have not been mapped.