But look again, and you will see that along the west coast of Ireland, except in a very few places, like Galway Bay, the blue limestone does not come down to the sea; the shore is coloured purple and brown, and those colours mark the ancient rocks and high mountains of Mayo and Galway and Kerry, which stand as barriers to keep the raging surf of the Atlantic from bursting inland and beating away, as it surely would in course of time, the low flat limestone plain of the middle of Ireland.  But the same coral-reefs once stretched out far to the westward into the Atlantic Ocean; and you may see the proof upon that map.  For in the western bays, in Clew Bay with its hundred islands, and Galway Bay with its Isles of Arran, and beautiful Kenmare, and beautiful Bantry, you see little blue spots, which are low limestone islands, standing in the sea, overhung by mountains far aloft.  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,