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faulted against the Lower Bunter Sandstone. The mineral barium 
has been found in this delf. 
The Cefn-y-Fedw Sandstone to the north of Flintshire, at 
Holywell, Gronant, and Talacre, is supposed to represent the 
Millstone Grit series in that district. 
Although the Coal-measures do not embrace an extensive area 
in the radius, they are certainly of the greatest commercial value 
and importance. The strata of this formation are divided into 
Upper, Middle, and Lower. The Lower Coal-measures at Billinge 
are, according to Professor Hull, F.R.S., about 1800 feet in thick- 
ness. At the Bispham Hall Colliery, near the highest part of 
Billinge Hill, which is 593 feet above sea-level, the thickness of 
the coal-seams varies from 1 foot 8 inches to 2 ft 6 inches, the depth 
of the shaft is only 60 yards, and the coal-seams are worked in what 
are known as the ‘‘Mountain Mines.” In the strata of these Lower 
Coal-measures, as a rule, thin coal-seams only are found, which are 
therefore not regarded as of special importance to the miner. The 
Middle, or Productive Coal-measures, are developed about St. 
Helens and Prescot, and are justly regarded as valuable, and of 
vital importance to the trade and commerce of the district. 
These Coal-measures consist of alternations of sandstones, 
shales, and coal-seams. At Doulton’s Delf, St. Helens, an 
excellent section in the lower strata of the Middle Coal-measures 
can be seen. This section is over 100 feet in thickness, and consists 
of shales, sandstones, pottery clay, and thin seams of coal. The 
delf is rich in characteristic fossil plants consisting of Catamites , 
Sigillaria , Stigmaria, Lepidodendron , Lepidostrobus, Halonia, Cordaites, 
Sphenophyllum, and ferns. Casts of the trunks of trees such as 
Sigillaria and Catamites can be seen standing erect, as if in the 
position in which they grew. 
Out-crops of coal seams occur in the district around St. Helens, 
and the town is built upon the strata of the Middle Coal-measures. 
Fish remains occur in these rocks, and the characteristic shells 
Anthracosia robusta and Anthracosia acuta are found. The latter is in 
abundance at Doulton’s Delf. 
Coal has been mined at various places near Neston, in the 
peninsula of Wirral, for nearly 150 years. This inlier, or patch 
of Middle Coal-measures, which is probably the eastern limit of the 
North Wales Coalfield, is small in extent, and has been preserved 
by being faulted against the Lower Bunter Sandstone. 
The colliery at Neston, the shaft of which is 450 feet deep, 
