Ahem! Ahem! (Pebble coughing.) I caught cold some several million years ago and I haven't got over it yet. That's why I'm a granite pebble instead of a slate pebble, or a sandstone pebble, or anything common. It's a part of the story of the fairyland of change, this cold of mine. Ahem! Would you mind getting me a lump of sugar? I don't want it for my cold--it never does that any good--but because a lump of sugar goes so well with this part of my story. You notice the sugar lump is made up of little crystals, little building blocks just as I am, just as all granites are. And the crystals in the sugar and in the stone were made in the same way--by first heating and then cooling the material out of which they are made. [Illustration: THE CRYSTAL FAIRIES IN THE SUGAR-BOWL] When the earth's surface first cooled, the melted rock is supposed to have changed to granite. Melted rock, under the same conditions, does that to-day. So, for a while, granite must have been all the kind of rock there was. There was as yet no sandstone, no shells or bones to make limestone, no pebbles to help make conglomerate or "pudding stone," no ground-up rock and soil to make slate. The rocks of the earth have been made over so many times that it is not probable that any of the granites now "living" (so to speak) are the same rocks that were made when the earth first cooled, but you can see that we have a right to say what I was careful to say when I introduced myself to you in the first chapter, that we belong to one of the _very oldest families_--we Granites. Ahem! There is a variety of rock--a crystallized rock--with bands all through it, called gneiss (say "nice"). Gneiss is made from all kinds of rock including, of course, conglomerate; that is to say "pudding stone"[16] warmed over. [Footnote 16: "Pudding stone" is a rock with pebbles all through it, like the plums in a Christmas pudding. Its book name is "conglomerate."] "And what they did not eat that night, the queen next morning fried!" DOWN IN THE GREAT MELTING-POT But how is old rock warmed over and made into new? You might easily guess that as the heart of the earth is melted rock the rock layers lying next to it would be melted, too, and so started on their way to becoming crystallized rock. Crystallization in rock takes place from the surface down, in the same way that maple syrup turns to sugar, as it does if allowed to stand undisturbed. So, as the central mass of rock is cooling from above toward the centre, we may suppose granite is still being formed away down there, miles under our feet. But there are other ways in which rocks make their own heat--rocks far above this central molten heart of the world. One of these ways might remind you of how the mother hen gets her chickens to come out of the eggs, for rocks hatch out new rocks by sitting on one another! [Illustration: THREE CHAPTERS IN THE STORY OF MARBLE