And the wind is a good friend to the good farmer, but no friend to the poor one; for it carries away dust all nicely ground from the fields of the farmer who doesn't protect his soil and carries it to farmers who have wood lots and good pastures and winter wheat, and leaves it there; for woods and pastures and sown fields hold the soil they have, as well as the fresh, new soil the winds bring to them.
Most of the fine prairie soils in our Western States owe not a little of their richness to wind-borne dust. In western Missouri, southwestern Iowa, and southeastern Nebraska are deep deposits of yellowish-brown soil, the gift of the winds. And, my, what apples it raises! It is in this soil that many of the best apple orchards of these States are located. And now, of course, the apple-growers see to it that this soil stays at home.
But there's another kind of dust that deserves special mention, and that's the kind of dust that comes from volcanoes. Volcanoes make a very valuable kind of soil material, often called "volcanic ash." It isn't ashes, really. It's the very fine dust made by the explosion of the steam in the rocks thrown out by the volcano. The pores of the rocks, deep-buried in the earth, are filled with water, and when these rocks get into a volcanic explosion, this water turns to steam, and the steam not only blows out through the crater of the volcano, but the rocks themselves are blown to dust. This dust the winds catch and distribute far and wide. Sometimes the dust of a volcanic explosion is carried around the world. In the eruption of Krakatoa, in 1883, its dust was carried around the earth, not once but many times. The progress of this dust was recorded by the brilliant sunsets it caused. It is probable that every place on the earth has dust brought by the wind from every other place. So you see if you happen to be a grain of dust yourself, and keep your eyes and ears open, you can learn a lot, as I did, just from the other little dust people you meet.
THE WINDS AND VOLCANOES
But that isn't all of this business—this partnership—between the volcanoes and the winds. Did anybody ever tell you how the volcanoes help the winds to help the plants to get their breath? It's curious. And more than that, it's so important—this part of the work—that if it weren't carried on in just the way it is, we'd all of us—all the living world, plants and animals—soon mingle our dust with that of the early settlers we read about in the last chapter. In other words, all the plant world would die for lack of fresh air and all the animal world would die for lack of fresh vegetables. So they say!
According to that fine system—the breath exchange between the people of the plant and animal kingdoms—the plants breathe in the carbon gas that the animals breathe out; you remember about that. But the amount of carbon gas in the air is never very large, and if there were no other supply to draw on except the breath of animals and the release of this same gas when the plants themselves decay, we'd very soon run out.
Now this needed additional supply comes from the volcanoes. Every time a volcano goes off—and they're always going off somewhere along the world's great firing-line—it throws out great quantities of this gas, and this also the winds distribute widely and mix through the atmosphere.
And another thing: This carbon in the air helps crumble up the rocks already made, and it enters into the manufacture of the limestone in the rock mills of the sea. This limestone will make just as rich soil for the farmers of the future as the limestones of other ages have made for the famous Blue-Grass region of Kentucky, for example.
All of which only goes to show how first unpleasant impressions about people and things are often wrong. A "dusty March day," you see, isn't just a dusty March day. It's quite an affair!