LESSON IV.

THE REIGN OF THE PINES AND THE REPTILES.

“A monster then, a dream,A discord. Dragons of the prime,That tear each other in their slime,Were mellow music, matched with him.”—

“A monster then, a dream,

A discord. Dragons of the prime,

That tear each other in their slime,

Were mellow music, matched with him.”—

—Tennyson,In Memoriam.

GNOMES IN A CAVE AT WORK.

We have now reached the middle period of the earth-building story. We have thus far seen how from a great globe of burning gas, our earth shrank, cooled, hardened, became wrapped in waters, uplifted continents and islands,and through successive periods became filled with plants and animals of sea and land. The period at which we have now arrived was the age of wonderful monsters, of pines, and of palms. For the first time also the earth was splendid with flowers. The seas grew constantly cooler, and the earth crust as constantly thickened. As the seas cooled less vapor rose into the air, the atmosphere cleared, and a bright sunshine poured over the continents.

The continents of this middle period of world-building were some of them larger than now. Probably North America stretched over much nearer to Europe; England was not an island, but was joined to the mainland of Europe, and extended far south and west in what is now the sea. The mountains were very high, so high that it has been supposed that they had snow-covered tops, and glaciers formed in their gorges, and icebergs, breaking from the glaciers, sailed off to distant seas.

At this time the earth was green with ferns and grasses and dark with forests. Among the most noble of the trees were the cycads. They were partly like pines, and partly like palms. Beside the cycads grew great pines, and probably pines were the distinguishing trees of this cycle. The vegetation was more like the present vegetation of the tropics than like that of northern climates, because the earth was warmer then than now.

In our last lesson we spoke of the red sandstone as a very rapid deposit of sand by water. When the deposit is slow, the red color is washed out of the sand by the action of air and water. This red of the red sandstone is due to iron-rust,which stains the sand as it does iron or steel. When the deposit of these stained sands is rapid, in thick beds, the color does not have time to bleach out. There are two vast layers of this red sandstone, the old and the new. The new is largely present in the beds of the middle period of world-building, and sometimes gives the first age its name—the age of the New Red Sandstone. The northern shore of Scotland is banded by the old red sandstone, as if held in a sandstone frame.

Another rock of this time is called conglomerate, or mixed stone. Some call it “pudding-stone,” and say it looks like a pudding full of plums and lumps of suet. Such stone is very common, various kinds of pebbles and rocks being held together as if they had been baked or boiled into one mass. Near the conglomerate we sometimes find limestone full of tiny broken shells, and also beds of marl. Marl is a rich greenish earth, which crumbles easily and is valued for enriching cultivated lands.[13]All these varieties of rock are interesting when we study them, and can read the stories they tell of long-gone ages, of fire, volcanoes, earthquakes, floods, storms,—where strange animals and plants lived and died.

Do we ever stop to think what a treasure-house of wonders and of choice and beautiful things the earth is? There are sands filled with grains of pure gold, and rocks where gold glows in grains and veins and nuggets. I have seen lumps of silver-bearing rock which look as if in some age of heat the pure silver had melted, boiled, and bubbled until now it lies in the stone in curious shapes, like balls, and stars,and chains, and moss, and tiny trees,—all fantastic and pretty forms. There are mines where diamonds, and rubies, and garnets, and sapphires lie hid as if the gnomes, or fabled earth-spirits, had stored them away. What crystals shine among the rocks, and red bands of carnelian glow, and purple amethysts and vivid carbuncles blaze! Kings have rooms full of such treasures kept for show; but the silent earth hides in her bosom many more and far richer jewels.

Come here, and let me show you just one marvel made in the earth in some of these long building periods, when heat was working wonders. Since you have been handling all these minerals and curiosities your hands are dirty. Take this towel and wipe them. Look at the towel. What do you see?

“Just a coarse cotton towel,” you say; “nothing fine about that.”

“Very well. Have you wiped your hands? Here, let me throw the towel into the fire.” You stare at that.

“Do you always burn your towels?” you ask.

“I never burn them up. I just wash them in fire. Look sharp!” You look. The fire curls into and over and about the towel, and it becomes red hot, yet does not fall into ashes. Watch me. I take the tongs and pick my towel from the fire. As it is, red hot, I dip it into a pail of water. Now it is cool, pray take it and examine it. It is clean and whole as if new! That towel is made of rock! It is called asbestos. It is a very hard rock, and lies in layers of fine, silky fibres. You can pull these fibres or threads off, and apart, like flax; they can be spun and woven. Plenty of it is foundin Canada. See, it looks like common cotton cloth. Found in thin sheets it is called “mountain-leather,” in thick sheets it is named “mountain-cork.” But it is all asbestos—a rock fibre. And what do they do with it? They mix fire-proof paints with it; make boiler felting; firemen’s cloaks; gloves for fire-workers. Long ago the ancients wrapped dead bodies in it, so that their ashes might not be lost when they were burned upon the funeral pyre. Wonderful stuff, is it not? But the brown still earth is full of such wonders.

Let us return to look at the products of the middle period of earth-building, and see how the world grows more and more fit to be the home of the coming man. We find now palm, fig, oak, tulip, walnut, and sweet-gum trees. As all these trees produce fruits, seeds, or nuts suitable for food for animals, we should look for animals to feed upon them.

We find the fossil bones of some of the dwellers in these woods; the rocks also retain their footprints. The great creatures, marching over the soft earth and mud, made deep tracks, and these remained like casts or moulds as the soil hardened; then sand and other sediment were deposited over them, and so the footprints were encased. The deposit, hardened into rock, has preserved the footprints for thousands of years. Strange that a thing so fleeting as a footprint on sand should remain to tell a story for ages!

But what of the creatures that made these footprints? These were huge, two-legged animals with three-toed feet, stalking through the woods, and calmly browsing on the tree-tops! Science reconstructs some of these creatures, and finds that they had small heads, long necks, huge tails, andthick legs. These were mild but hideous creatures, and munched nuts and fruits. They may have glistened in the colors of the rainbow for all we can tell, but even color could not make beautiful a creature with a giraffe’s neck, an elephant’s legs, a crocodile’s tail, and a kangaroo’s head.

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 wehad 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.

Stuck all through this chalk, like plums in a cake, arehard flints or pebbles, and these can be cut and polished into very pretty jewelry.

The Chalk age was one of great and violent changes. Once more the continents began to sink. The earth-crust could not uphold the mighty weight of deposit upon it. The shrinking and cooling core caused the settling of vast stretches of land, and the continents were depressed lower than they had been since the time of the first continent. Down, down went the land, and over it the waters flowed, and where hills and forests had been, creatures of the deepest depths of ocean played. Europe probably settled lower than America.

Once more the globe was like a vast ocean, above which rose what had been high ranges of mountains, now forming long islands or reefs. Of these surrounding ridges might have been noted the hills of Great Britain, the Scandinavian Mountains, and the Ural range. In the Western hemisphere the hills of the St. Lawrence and the Appalachian Mountains rose over the water, and here and there a peak of the Rockies or the Andes.

Why did the little hills of Britain rise up when the great Alps and the Himalayas were not to be seen? Britain itself did not sink so low at that time, and the Alps and the Himalayas were not yet born. They rose at a later day. The seas ebbed and flowed and deposited their chalk sediment over a drowned globe for a very long time. Then once more the earth crumpled, and amid earthquakes and volcanoes the Chalk age perished, the Rocky Mountains, Alps, and Himalayas were crowded and tilted up to be the great mountain-ranges of the world, and the last building-time of the earth had come.

FOOTNOTES:[13]Marl is also used with sand in making Portland cement.

[13]Marl is also used with sand in making Portland cement.

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