The details in the following section are derived from  records containing shaft sections at Pleasley and other pits compiled by Mr G. A. Longden, one of the early managers, and from a book containing a copy of Mr Longden’s records annotated with the results of a re-survey conducted in 1946/47. They are complemented by information obtained from mine water drainage plans and from underground survey measurements shown on the abandonment plans held by the Coal Authority central records office at Berry Hill in Mansfield.

Mr Longdens records are believed to have been prepared for a paper presented to the Midlands Institute of Mining Engineer in the 1920s. They contain a few minor miscalculations which have been corrected at some point, possibly as part of the 46/47 re-survey. The values shown for the North shaft are in close agreement with the drainage and abandonment plans but those for the South pit show a marked inconsistency throughout the section, with a difference of 32 - 34 ft. between Mr Longdens values and the actual values.

This would seem to arise because the section records for the South shaft commence at the Top Hard seam level and, unfortunately, the reference level used was that of the Top Hard level in the North shaft. 

Although we do not have the South shaft section from the surface down to this point, it is possible to make an estimate of the correct depth for the Top Hard in this shaft.   Whilst at the surface, the South pit-top is at a lower elevation than the North one, this is not the case underground.  In a paper describing the electric haulage systems installed at Pleasley in the 1890s, the dip of the Top Hard main roadways in the seam near the shafts is given as 1 in 12 towards the North shaft.   The two shafts are approximately 285 ft. apart, hence the difference in depth due to the inclination of the strata will be about 24 ft.

It is not clear whether the measurements given by Mr. Longden refer to the original ground surface at the time of sinking, or to the subsequent decking levels of the pit top itself - although later measurements will most likely refer to the decking level. Both North and South pit-tops have been reconstructed at various times and their elevations have changed as a result.  For instance, when the new headstock was installed at the North pit in 1901, a new pit-top level had to be constructed above the 15 inch high bedframe of the new headstock, thus raising the decking level by maybe 18 inches or more.  At the South pit, it is not clear what change in level, if any, occurred when the pit-top was reconstructed in 1900. There is now, however, a difference in elevation between the N and S pit tops of 6 ft. but even after this is taken into consideration, it still does not entirely explain the difference.

Account needs to be taken of the relative depths of the Top Hard  underground running on levels, with both shaft-side roadways at abandonment shown as being 16 ft high but it is not clear at the moment whether the residual difference lies in this quarter.