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of the Silkstone seam, with beds obtained in collieries to the 
north of our imaginary line of separation. 
Whether these authorities may all agree amongst them- 
selves, and ultimately prove to be correct, is more than I can 
venture to assert. I am free to admit that it is possible. 
But the evidence requires much care in its adequate collection 
and examination before it is fully accepted. I know my 
friend. Professor Green, has lent the importance of his high 
authority to the Blocking Bed," a seam locally known in 
the district of Dewsbury and Flockton, as the true representa- 
tive of the Silkstone, and his forthcoming Memoir, will doubt- 
less convey such reasons as will claim our deepest respect. 
Mr. Thorp's diagram may also be referred to, as confirming 
this identity. 
I will, however, anticipate the pleasure with which I am 
sure Professor Green's work will be hailed, by suggesting a 
line of investigation, which it is just probable he may not 
have pursued. I will now refer to that analogy, which may 
or may not be traced, between the lower members of the West 
Riding section, by pursuing them upwards from the great 
Millstone Grit base, which is well defined along the western 
and northern boundaries of our entire Coal-field, and extend- 
ing from Sheffield in the south, by Huddersfield, Halifax, and 
Denholme, in the west, to Kirkstall, Horsforth, and Thorner, 
in the north. 
It is not a little remarkable, that along this extended line 
of country, the two Halifax beds (the Hard Bed and the Soft 
Bed Coals) are to be traced in consistent relation to the out- 
cropping Grit- stone, which lies in varying thicknesses of 15 
to 25 or 30 yards, below the Soft or lower bed. The Halifax 
beds are overlaid by a series of alternating shales and 
bind, interspersed with a few very thin, but distinctive 
" bands " of coal, and generally, acquiring an aggregate 
thickness of 150 to 200 yards. The section then receives, in 
