The Woogill Coal, near the base of the Red Scar Grit, was worked extensively in Colsterdale. The seam at Brown Beck, which dips gently eastwards, has also been worked on Braithwaite Moor and at Sowden Beck, both in East Witton township. The coal was 10 inches (0.25m) thick near Brown Beck Low Shaft, but increased to 18 inches (0.45m) near the High Shaft. The output of this mine was principally lime coal.
In the High Gill workings, at Thorney Grain in Colsterdale, the seam varied between 16 and 20 inches (0.4 and 0.5m) in thickness, but sometimes it was nearer 12 inches (0.3m). The quality of the coal was also higher and the pits produced more fire coal than lime coal.
The seam was also tried at Arnagill, six kilometres south-east of the High Gill, but it was soon given up as uneconomic.
Gill, M.C. “Great Dales Coalfield, Eastern Areas” British Mining No.86 (2008), pp.68-108
Tyson L.O. Mashamshire Collieries, British Mining No.82, 2007