Part 4 (2/2)

Shall we not now seek to learn which of the natural resources of our land will never be replaced if we squander them? Let us also learn which may be made good again by Nature, if we are willing to wait long enough, as well as to a.s.sist her in her slow work.

Each year the growing plants take certain substances from the soil. It is necessary for us to put back like substances if we would keep up the fertility of the soil. If we are neglectful of this law, or allow water to wash the soil away until only the bare rocks remain, poverty will be our lot for many years.

Nature will, however, if we give her a chance, renew the soil. The rocks will crumble and, by and by, seeds will sprout and tiny plants obtain a foothold. But it may take a whole lifetime, or hundreds of years, even, for a new and fertile soil to come again.

During the early years of placer mining in California thousands of acres of rich lands in the foothills were destroyed. Only boulders were left.

Now fifty years have pa.s.sed and a new soil is being formed, but it will be a long time yet before it will be as good as it was in the first place.

Upon the Western prairies only grain has been raised for so many years that in many places the soil will scarcely grow a crop worth gathering.

Many farmers have never thought of this, but the wise ones understand that they must frequently add plant food to the soil to replace that taken by crops. They understand also that it is a good thing to change the crops grown upon any particular field from year to year, since different plants take different substances from the soil.

[Ill.u.s.tration: _H. W. Fairbanks_ The miner in his search for gold ruins the beautiful valley, leaving it a ma.s.s of boulders.]

Water goes through a ceaseless round. It rises from the sea and lakes to form the clouds, falls as rain or snow, and then flows back down the slopes to the sea. Although we have learned that we cannot change the quant.i.ty of rain that falls in any place, we can influence the way in which it runs back to the sea. This in turn affects the lives of people.

We can store water in reservoirs, and by building ca.n.a.ls have it to use on the land during the summer. We can also keep it from flowing back to the sea as rapidly as it otherwise would, by leaving uninjured the covering of vegetation which has been spread over the mountain slopes.

The water will run from bare rocks and bare soil much more quickly than it will from soil that is covered with leaf mold and held by plant roots. Do you not see, then, that we have almost as much control over water and its distribution as though we could increase or decrease the rainfall?

What about the forests? If we cut them down, will they ever come back?

All through the eastern part of our country and in the mountains of the West are lands once forested which have been cleared and turned into farms. Many of these farms, when abandoned, have in a few years been covered with a growth of young trees. The scattering trees that had been left in the vicinity of the clearings furnished the seed. The winds and the birds carried the seed to the open fields and so the forests began again.

[Ill.u.s.tration: _H. W. Fairbanks_ But Nature, after a lapse of fifty years, has spread a new carpet of soil over the valley.]

It will be hundreds of years before the trees are as large and valuable as those of the first forest. The ”big trees” of the Sierra Nevada Mountains are found nowhere else in the world, for they are the last of their race. Some of these trees are more than 4000 years old.

They stood here when our forefathers were still savages and lived in trees or caves. Much of the region where these trees are found has now been reserved as a park. If the lumberman had been allowed to get at them, they would have soon been gone forever.

[Ill.u.s.tration: _George J. Young_ Uncle Sam has preserved both forests and water power.]

It is far more difficult to destroy completely most of the species of forest trees than it is to destroy the species of animals and birds. We can cut down the trees and in some cases they will grow again from sprouts. Many will hide away in remote places and furnish seed for new forests.

The animals as well as the plants have had a long history. They have had a harder struggle than the plants, because many of them prey upon one another. We often dig up the skeletons of strange animals unlike any now living. These must have all been killed long ago. Each species or kind of animal now living must have come off victorious in the struggle with its enemies.

Does it not seem a heartless thing for us, who call ourselves civilized, to destroy so completely any species of animal or plant that not one of its kind remains alive? No species which we destroy will ever come back again, and its place will always remain empty. There are a few predatory animals and birds that destroy vast numbers of useful ones. We should keep these in check by every means in our power, but for our thoughtless destruction of the valuable ones the world will always be poorer.

What of the mineral treasures hidden away in the earth? Will these be replaced when once they have all been used up? It took Nature a very long time to make coal out of the vegetation which had gathered in some ancient swamp. It took her fully as long to make the oil and gas from the bodies of the little organisms that once lived in the sea.

The bodies of the little creatures from which oil is made are still gathering upon the bottom of the sea, and there are many swamps where we find vegetation and peat acc.u.mulating. But it is a long story from these substances to oil and coal. I am afraid we should get tired of waiting for Nature to make a new supply.

Gold, silver, copper, and other minerals, so useful to us, are found in very small quant.i.ties scattered throughout most of the solid rocks of the earth. It would be impossible for us to obtain these from rocks, because there is so little in any one place. But Nature has collected a part of them in veins in the rocks. We sink shafts upon these veins and mine the ores. It will be a long time before we shall have mined all there is of these minerals. Because they are so hard to get we are not likely to waste them. But it is quite certain that there is a limit to the supply of mineral treasures, and equally certain that they can be renewed either very, very slowly, or not at all. Shall we cause our remote descendants to suffer for our carelessness?

CHAPTER EIGHT

THE SOIL--THE MOST IMPORTANT GIFT OF NATURE

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