258 
ASHLEY : NOTES OX ADWALTON AND HALIFAX COAL. 
The Hard Coal extends from the neighbourhood of Shipley 
right along the western edge of the coalfield through Halifax, 
Huddersfield, Penistone, and, although not shown on the map 
(Plate XL VII.), the seam is known to exist right to the southern 
extremity of the coalfield near iS"ottingham. 
Thickness of the Seam. On the plan (Plate XL VII.), the 
points where the bed has been proved are shown, the thickness 
of the seam beins: Sfiven. It has onlv been worked at and near 
its outcrop on account of the increasing depth to the east, the 
measures dipping in that direction. 
Starting at a point about six miles north of Sheffield, the 
seam is found 2 feet 3 inches thick. Going north, it varies in 
thickness a few inches only, until New Mills is reached, where 
it is found only 1 foot 6 inches thick. It, however, soon thickens 
out at Huddersfield, averaging about 2 feet 3 inches, this thick- 
ness being maintained until Queensbury, on the north side of 
Halifax, is reached. 
It thins out somewhat to the north and is found in outlying 
patches brought in by faults, as at Baildon and Rawdon. 
North of Leeds it is found only a few inches thick. 
Underlying Strata. The floor underlying this seam is, except 
in the neighbourhood of Queensbury, a hard ganister, consisting 
almost entirely of silica. 
Underneath this ganister a bed of fireclay is generally found, 
in some places worked extensively. North of Queensbury, how- 
ever, the fireclay is found immediately under the coal. 
Overlying Strata. The roof is a shale full of Aviculopecten 
papyraceus, Goniatites, and other marine fossils. Plate XLVIIf. is 
a section of the coal along its outcrop, which runs approximately 
north and south, and is drawn on the same scale as that of the 
cannel coal (Plate XLVL). 
C03JPARIS0X OF THE TWO SEAMS. 
Upon comparing the two seams, it will be noticed the thick- 
ness of the Halifax Hard Coal as compared to the cannel coal 
is extremely uniform. The length of the section of the Hard 
