You have often heard those islands in Kenmare Bay talked of, and how some whom you know go to fish round them by night for turbot and conger; and when you hear them spoken of again, you must recollect that they are the last fragments of a great fringing coral-reef, which will in a few thousand years follow the fate of the rest, and be eaten up by the waves, while the mountains of hard rock stand round them still unchanged.
Now look at England, and there you will see patches at least of a great coral-reef which was forming at the same time as that Irish one, and on which perhaps some of your schoolfellows have often stood. You have heard of St. Vincent's Rocks at Bristol, and the marble cliffs, 250 feet in height, covered in part with rich wood and rare flowers, and the Avon running through the narrow gorge, and the stately ships sailing far below your feet from Bristol to the Severn sea. And you may see, for here they are, corals from St. Vincent's Rocks, cut and polished, showing too that they also, like the Dudley limestone, are made up of corals and of coral-mud.
Now, whenever you see St. Vincent's Rocks, as I suspect you very soon will, recollect where you are, and use your fancy, to paint for yourself a picture as strange as it is true. 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. They are all made up of the carboniferous limestone, so called, as your little knowledge of Latin ought to tell you, because it carries the coal; because the coalfields usually lie upon it. It may be impossible in your eyes: but remember always that nothing is impossible with God.
But you said that the coal was made from plants and trees, and did plants and trees grow on this coral-reef?
That I cannot say. Trees may have grown on the dry parts of the reef, as cocoa-nuts grow now in the Pacific. But the coal was not laid down upon it till long afterwards, when it had gone through many and strange changes. For all through the chine of England, and in a part of Ireland too, there lies upon the top of the limestone a hard gritty rock, in some places three thousand feet thick, which is commonly called "the mill-stone grit." And above that again the coal begins. Now to make that 3000 feet of hard rock, what must have happened? The sea-bottom must have sunk, slowly no doubt, carrying the coral-reefs down with it, 3000 feet at least. And meanwhile sand and mud, made from the wearing away of the old lands in the North must have settled down upon it. I say from the North--for there are no fossils, as far as I know, or sign of life, in these rocks of mill-stone grit; and therefore it is reasonable to suppose that they were brought from a cold current at the Pole, too cold to allow sea-beasts to live,--quite cold enough, certainly, to kill coral insects, who could only thrive in warm water coming from the South.
Then, to go on with my story, upon the top of these mill-stone grits came sand and mud, and peat, and trees, and plants, washed out to sea, as far as we can guess, from the mouths of vast rivers flowing from the West, rivers as vast as the Amazon, the Mississippi, or the Orinoco are now; and so in long ages, upon the top of the limestone and upon the top of the mill-stone grit, were laid down those beds of coal which you see burnt now in every fire.