In 1589, Robert Bowes of Barnes, former ambassador to Scotland and John Smith, a merchant from King's Lynn leased land on the south bank of the Wear and built ten iron salt pans. This piece of land between Sunderland and Bishopwearmouth being known as the Panns to this today (as in Panns Bank, Pann Lane). The coal for this venture was brought downriver from various sources, one of which being Offerton, where a pit was sunk for this purpose. Low ranking coal was used to fire the salt pans, and the higher grade coal was exported alongside the salt. In Offerton Dene there are large open spaces punctuated by large mounds, some of which appear to be recent deposits. It seems that there is some depth of sediment built up over the floor of the dene. Two large areas of refuse are shown on the first edition Ordnance Survey which may have been backfilled into the dene. The dene is shown in Thomas McCree Scott's 1918 painting Offerton Dene, near Sunderland (9.5" x 13.5" watercolour), this artwork is currently in private ownership. Visible in the dene are tooling marks on the exposed bedrock and worked masonry. The first edition Ordnance Survey map shows the path of the stream which enters the dene. This stream does not simply flow downhill from its origin at a well spring behind Offerton village but follows field boundaries in straight lines and has possibly been diverted for agricultural purposes and possibly hushing (mining by artificial erosion). The stream is now culverted and can be seen entering the top of the dene from a pipe, the base of the dene is waterlogged near this pipe but the ground level has risen to deny it any egress and the final reach of the stream which connected the end of the dene to the nearby river has vanished. Offerton is known for historic stone quarries, some of which are marked as 'old' on the first edition Ordnance Survey maps. The nearest of these is HER 3066 (NZ 3446 5601). This site may have been quarried since at some point before, during or after the sixteenth century. This would not preclude it being the site of the coal mine. The site in question's sheer size and riverside location would suggest that it is the obvious site for the sixteenth century pit.