Fancy that those rocks are what they once were, a coral-reef close to the surface of a shallow sea.
Fancy that there is no gorge of the Avon, no wide Severn sea--for those were eaten out by water ages and ages afterwards.

But picture to yourself the coral sea reaching away to the north, to the foot of the Welsh mountains; and then fancy yourself, if you will, in a canoe, paddling up through the coral-reefs, north and still north, up the valley down which the Severn now flows, up through what is now Worcestershire, then up through Staffordshire, then through Derbyshire, into Yorkshire, and so on through Durham and Northumberland, till your find yourself stopped by the Ettrick hills in Scotland; while all to the westward of you, where is now the greater part of England, was open sea.

You may say, if you know anything of the geography of England, "Impossible! That would be to paddle over the tops of high mountains; over the top of the Peak in Derbyshire, over the top of High Craven and Whernside and Pen-y- gent and Cross Fell, and to paddle too over the Cheviot Hills, which part England and Scotland." I know it, my child, I know it.

But so it was once on a time.

The high limestone mountains which part Lancashire and Yorkshire--the very chine and backbone of England--were once coral-reefs at the bottom of the sea.