t6 THE YORKSHIRE COALFIELD 
Geologically, the Yorkshire coalfield is related to that 
of Lancashire. But Yorkshire coal has its own well- 
defined characteristics, though these vary to such a degree 
that the general field, divided into West and South York- 
shire, has some fifty different seams. The former has 
thirty-one distinct seams of coal, with about one-third of 
the total output, having Wakefield as the trade centre; the 
latter has nineteen seams, with two-thirds of the output, 
which is mostly centred for market purposes round Barnsley. 
The principal seams now being worked are the following : 
West Yorkshire. South Yorkshire. 
Woodmoor. Shafton. 
Warren House. Barnsley Bed. 
Haigh Moor. Swallow Wood. 
Flockton. Parkgate. 
Middleton Main or Silkstone. Thorncliffe. 
Beeston. Silkstone. 
Stanley Main. Lidgett. 
These seams include every variety of house, gas, steam, 
coking and manufacturing coal. All seams, however, have 
their local variations, so that the virtues of one seam may 
disappear in one district and reappear in another. Thus, 
the Swallow Wood coal of South Yorkshire is only workable 
in the neighbourhood of Rotherham, and is there a good 
steam coal. Going north it merges into the Haigh Moor 
seam, where it appears as a high-class house and gas coal. 
Broadly speaking, the distinctive features of West York- 
shire fields are house and manufacturing coal, and of South 
Yorkshire, steam, house and gas coal. In West Yorkshire 
the depth of present workings is generally less over the 
whole area than in South Yorkshire. The dip of the 
strata declines strongly towards the east. The most 
important among the deeper workings of the Barnsley bed 
seam run from 800 to 840 yards down, a depth which is 
about the limit of convenient working. Borings made 
some six miles east of any existing workings have, however, 
proved the seam to be of good quality at a depth of 1,016