FROM THE LOWER CARBONIFEROUS OF NORTH WALES. 
rise to a porous sandy mass when 
the lime is removed by weather- 
ing. We have been unable to de- 
tect any organic remains in it, 
even with the aid of the micro- 
scope. In all these respects it 
contrasts with the Carboniferous 
Limestone proper, which is free 
from grit, and is almost entirely 
made up of fragments of Corals, 
Encrinites, and Foraminifera. 
This brecciated limestone is lo- 
cally known as the Bastard Lime- 
stone. 
The unconformable position of 
the Bastard Limestone on the 
Wenlock shale is shown in a quarry 
on the west side of the dingle, 
and in a pit 150 yards further to 
the west. The shale dips to the 
north at from 6° to 7°. Its bedding 
planes are cut off towards the north 
by the Bastard Limestone, which 
dips to the N.N.E. at from 26° 
to 27°. A little local breccia, con- — 
sisting of small fragments of Wen- 
lock shale in a red clay or brown 
earth, about from 8 to 12 inches 
thick, separates the limestone from 
the surface of the Wenlock shale. 
The limestone is also exposed 
south-east of Twynan-uchaf and 
near Tyn-y-Pistyll, and has been 
proved in hematite trials near 
Orsedd, and in the slope of the 
hill below Cefn-uchaf and Cefn- 
y-Castell. It is represented at 
the Pile House, near Colwyn, by a 
porous sandy bed, slightly calca- 
reous, but in a much weathered 
condition. The Bastard Limestone 
occupies a position at the base of 
the beds about to be described 
over a considerable area. 
A great thickness of shales, 
sandstones, and conglomerates 
overlies the limestone. The fol- 
lowing details of the lower por- 
tion of these beds were obtained 
in Ffernant Dingle, in ascending 
order:— 
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