71 
seam has already, where the above sections are taken, become 
unworkable, and it is here that the belt of unproved ground, 
which has been already mentioned, is entered upon. 
It remains only to add, that, when a productive district 
is again reached, the place occupied on the south by the 
Silkstone coal is taken by the Blocking bed, a seam ranging 
from 1 foot 6 inches to 2 feet in thickness * 
The Barnsley coal has now to be described. Its marked 
distinguishing character is the occurrence in it of a band of 
^'hard" or -''steam" coal. This lies in the middle of the 
seam, the upper and lower portions being of the so-called 
bituminous " character. In the neighbourhood of Sheffield 
this coal ranges from 4 feet to 4 feet 6 inches in thickness ; 
going north it thickens, till at Rotherham it reaches 7 or 8 
feet, xlbout Barnsley it is at its best, ranging from 9 feet to 
10 feet, and sometimes even exceeding the latter figure. At 
Darton, near the station of that name, on the Lancashire and 
Yorkshire Railway, the coal is still of good quality, but a 
dirt parting, which first makes its appearance some way 
^outh of Barnsley, has somewhat increased in thickness. A 
little further on, as Haigh Station is approached, the coal 
has fallen off very considerably, and stiU further to the 
north, at Crigglestone, it has split up into so many small 
seams by dirt partings as to be utterly worthless ; and, 
further north, the writer has found it by personal explorings 
to be still further deteriorated. Then, as in the case of the 
Silkstone seam, comes a belt of unexplored ground ; and, 
after passing this, we find the coal, which occupies the same 
place as the Barnsley bed, putting on one form towards the 
north-east, and another towards the north-west. In the first 
* There is some difi'erence of opiniou about the identity of the Silkstone 
and Blocking coals. The reasons for thinking them equivalents will be given 
at length in the memoir of the Geological Survey on the Yorkshire Coal- 
field. 
