I think we may be very glad that we did not live in that age. Who could have played in a wood filled with such fearful creatures? Who would have wished to go out in a row boat, or for a little sail, when the sea was full of monsters, like sea-serpents, and all the rivers swarmed with huge reptiles? Little beasts like rats and kangaroos began to run in the woods, but there were no shy rabbits, no squirrels with full, waving tails and bright black eyes. What would woods be worth to ramble in, if not a bird flew, sang, or pecked upon a tree? We can fancy that far down in the heart of the earth the fabulous creatures, the gnomes, were busy. The Danes and the Germans have tales of queer little men, called gnomes, which live and work underground, and have charge of all the metals and jewels in the earth. The gnomes wear little pointed caps, and shoes with pointed toes. If in this far-off age we had been gnomes, we should have seen in the earth beautiful crystals forming. Diamonds, rubies, emeralds, all the precious gems and all the choice, fine stones, such as carnelian and agate, are very hard and of close grain and can take a brilliant polish, but as they lie in the earth they may look dull and pale, and be covered with a crust or case of common stone or clay. Cutting and grinding bring out their clear light and beauty. If we had been gnomes, wandering through the interior of the earth, we should have wondered who and what the coming creature could be, for whom was stored up things so rich and rare and useful. For whom were the vast beds of iron, coal, salt, tin, veins of precious metals and gems, rivers of oil, storehouses of gas? And some day, as we worked with tiny pick and crowbar, we might hear coming to meet us the pick and spade of earth’s new master--man! But that would be long, long after the Mesozoic, or Middle age of world-building had passed away. As the ages followed each other, there would constantly be new treasures hidden for the gnomes to guard. As one layer after another was buried by new material, in the buried layers were left the bones, teeth, footprints, and remains of the reptiles, insects, birds, and land animals of the passing age. Every new earth-bed was a vast graveyard. The last age of the middle building-time was called the Cretaceous, or Chalk age, because during it such vast quantities of chalk were built into rocks. All the English coast along the Channel is lined with chalk cliffs. The chalk is soft and white and easily worked. When, in England, we went down on the sand beach, and wanted something to play with, we would take a lump of the chalk cliff and whittle out balls with our knives. When we were done playing we left the balls for the sea to carry off; it was so easy to cut more. I often saw stables, cow stalls, wagon sheds, cut out of the chalk to save the farmer the trouble of building sheds of wood. The chalk cliff made fine, dry, clean houses for the animals.