253 
MOTES ON THE OCCURRENCE OF THE ADWALTON STONE COAL 
AND THE HALIFAX HARD COAL. 
BY THEODORE ASHLEY. 
{Read November 8th, 1900.) 
At the meetintr of the British Association at Bradford in 
September, 1900, a discussion was held with regard to the con- 
ditions under which coal was formed. It was suggested to the 
writer by Mr. Percy F. Kendall, F.G.S., that it would be useful 
to put on record all the facts which could be ascertained with 
reference to some definite seam or seams. In accordance with 
this suggestion the following details have been compiled, partly 
from information collected by the writer and partly from the 
records published by the Geological Survey. 
The seams of which a description is given are those known as 
(1) The Ad Walton Stone or Cannel Coal. 
(2) The Halifax Hard Bed Coal. 
These two seams were chosen as being the most different from each 
other in character of any in the north of the Yorkshire Coal Field, 
and at the same time as being thoroughly representative of their 
respective types. It is not proposed to deal in any wa}' with 
their chemical composition or their commercial value, but simply 
to give such facts regarding their occurrence as bear on the 
conditions of their formation. 
(1) The Adwalton Stone or Cannel Coal is found, as its 
name suggests, at the village of Adwalton, which lies about 
miles to the south-west of Leeds. It is not, however, here 
that it attains its greatest thickness. It occurs in the Middle 
Coal Measures lying about 130 yards above the Blocking or 
Silkstone seam, which is recognised as the dividing line between 
the Lower and Middle Coal Measures, and underlies an area 
bounded on the north by the village of Middleton, situated 
about a couple of miles to the south of Leeds, on the south by 
