212 Proceedings of the Royal Physical Society. 
them, but the Geological Survey describe the shales of 
Conisborough Pottery, Yorkshire, as “Red Beds with ey 
Plants.” 
I believe all these “red shales” are referable to the Upper 
Coal- Measures. 
MippLEe CoAL-MEASURES. 
Typical Area.—The Dudley Coal Field, South Staffordshire. 
The Middle Coal-Measures contain a great wealth of coal, 
and from strata of this age are derived the greater portion of 
the coals at present being raised in England. 
The whole of the coal seams of economic value in the 
South Staffordshire Coal Field are situated in the Middle 
Coal-Measures, which here lie unconformably on Silurian 
rocks. The most remarkable seam in this coal field is the 
“Thick Coal” or “Thirty Feet Seam,’ which, however, in 
the northern part of the coal field splits up into several 
separate seams. The “Thick Coal” is really formed by 
the running together of several beds of coal, varying in 
number from eight to fourteen, which rest either directly 
upon one another or are on ae by thin beds of “ clunch” 
or shale, called “ partings.” 
The “Thick Coal” is now mostly worked out in the neigh- 
bourhood of Dudley, so that the mining prosperity of that 
district now depends more on the other valuable seams, the 
total thickness of which, including the “Thick Coal,” is about 
65 feet.” 
The Thick Coal of South Staffordshire, by Herbert W. Hughes, 
p- 1. Sheffield, 1885. Reprint from the Jour. of the Brit. Soc. of Mining 
Students. 
? It is very generally stated that the Thick Coal is exhausted, and that it 
has been very badly worked. In reference to the first of these ideas, it may 
be said that there is now probably more unworked Thick Coal in South 
Staffordshire than there was considered to be twenty years ago; this being of 
course due to discoveries over the eastern boundary fault, and in the southern 
parts of the coal field. The author also believes that Thick Coal will 
eventually be found over the western boundary fault. H. W. , Hughes, 
ibid., Preface of reprint. 
This paragraph refers to the dices of the ‘‘ Thick Coal’’ at Sandwell 
Park, West Bromwich, and at Hamstead Colliery, Great Barr. 
