This millstone grit is a new and a very remarkable element in our
strange story. From Derby to Northumberland it forms vast and lofty
moors, capping, as at Whernside and Penygent, the highest limestone
hills with its hard, rough, barren, and unfossiliferous strata.
Wherever it is found, it lies on the top of the "mountain," or
carboniferous limestone. Almost everywhere, where coal is found in
England, it lies on the millstone grit. I speak roughly, for fear of
confusing my readers with details. The three deposits pass more or
less, in many places, into each other: but always in the order of
mountain limestone below, millstone grit on it, and coal on that
again.
Now what does its presence prove? What but this? That after the
great coral reefs which spread over Somersetshire and South Wales,
around the present estuary of the Severn,--and those, once perhaps
joined to them, which spread from Derby to Berwick, with a western
branch through North-east Wales,--were laid down--after all this, I
say, some change took place in the sea-bottom, and brought down on
the reefs of coral sheets of sand, which killed the corals and buried
them in grit. Does any reader wish for proof of this? Let him
examine the "cherty," or flinty, beds which so often appear where the
bottom of the millstone grit is passing into the top of the mountain
limestone--the beds, to give an instance, which are now quarried on
the top of the Halkin Mountain in Flintshire, for chert, which is
sent to Staffordshire to be ground down for the manufacture of china.
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