An entrance to extensive jet workings opened beside the footpath during forestry work in 2002 and was subsequently explored by the Moldywarps Speleo Group and Scarborough Cave Club. Nearly 1000m of passages were discovered, their investigation and mapping being covered in much details in Cleveland Industrial Archeology No. 30.
The entrance is now gated and locked, although looking down into an adjacent small collapse gives a good idea of the narrow and fragile passages through the shale.
In fields to the south west, three parallel collapses are visible and a large shale tip still scars the hillside. These show up particularly well if you click the “Show On Map” link at the top of this post.