The shallow coal workings dataset is derived from the Authority's records of underground coal mine workings. This dataset consists of all those underground coal workings with a recorded or interpolated depth from surface of 30m or less, with the exception of thicker seams where a depth of 50m will be applied. Underground workings do not readily constitute a threat to surface stability due to the ability of the overlying strata to dissipate any movement from within the workings before they reach the surface. However, shallow workings do not have sufficient overlying strata therefore any movement has the potential to reach the surface and cause damage.