STRANGE ADVENTURES IN NATURE'S WONDERLANDS

THE ADVENTURES
OF A GRAIN OF DUST

BY
HALLAM HAWKSWORTH

AUTHOR OF "THE STRANGE ADVENTURES OF A PEBBLE"

CHARLES SCRIBNER'S SONS
NEW YORK CHICAGO BOSTON

Copyright, 1922, by
CHARLES SCRIBNER'S SONS

Printed in the United States of America
C

JUST A WORD

I don't want you to think that I'm boasting, but I do believe I'm one of the greatest travellers that ever was; and if anybody, living or dead, has ever gone through with more than I have I'd like to hear about it.

Not that I've personally been in all the places or taken part in all the things I tell in this book—I don't mean to say that—but I do ask you to remember how long it is possible for a grain of dust to last, and how many other far-travelled and much-adventured dust grains it must meet and mix with in the course of its life.

The heart of the most enduring grains of dust is a little particle of sand, the very hardest part of the original rock fragment out of which it was made. That's what makes even the finest mud seem gritty when it dries on your feet. And the longer these sand grains last the harder they get, as you may say; for it is the hardest part that remains, of course, as the grain wears down. Moreover, the smaller it gets the less it wears. If it happens to be spending its time on the seashore, for example, the very same kind of waves that buffet it about so, waves that, farther down the beach hurl huge blocks of stone against the cliffs and crack them to pieces, not only do not wear away the sand grains, to speak of, but actually save them from wear. The water between the grains protects them; like little cushions. And the sand in the finer dust grains carried by the wind is protected by the material that gathers on its surface.

Why, if a pebble of the size of a hickory-nut may be ages and ages old—almost in the very form in which you see it,[1] think what the age of this long-enduring part of a grain of dust must be.

Then remember what the ever-changing material on the surface of these immortal grains is made of; the dust particles of plants and animals, of buried Cæsars and still older ancients, such as those early settlers of Chapter II.

Finally, if what we call flesh and blood can think and talk, why not a grain of dust? In fact, what is flesh and blood but dust come back to life? Says the poet—and the poets know:

"The very dust that blows along the street
Once whispered to its love that life is sweet."

You see it's as likely a thing as could happen—this whole story.

The Grain of Dust.
(Per H. H.)

CONTENTS

THE ILLUSTRATIONS

The author wishes to make special acknowledgment to the following publishers for their courtesy in supplying illustrations:

The Macmillan Company for the pictures from Tarr and Martin's "College Physiography" on page [239]; Darwin's "Formation of Vegetable Mould" on page [77].

D. Appleton and Company for the pictures from Gilbert and Brigham's "Introduction to Physical Geography" on page [94]; "Picturesque America" on page [243].

J. B. Lippincott Company for the pictures from Beard's "American Boy's Book of Bugs, Butterflies, and Beetles" on page [229]; McCook's "Natural History of the Agricultural Ant of Texas" on pages [206] and [213].

McClure's Magazine for the pictures on pages [149] and [157].

Scientific American Publishing Company for the picture from "Scientific American Boy at School" on page [227].

Harper and Brothers for the pictures from McCook's "Nature's Craftsmen" on pages [98], [105], [109], [207], and [208].

Strand Magazine for the pictures on pages [165], [182], and [204].

Charles Scribner's Sons for the pictures from Yard's "Top of the Continent" on page [5]; "Country Life Reader" on pages [9], [64], [85], [114], [186], and [241]; Osborn's "Men of the Old Stone Age" on page [33]. Hornaday's "American Natural History" on pages [116], [117], [119], [123], [130], [144], and [225]; Seton's "Life Histories of Northern Animals" on pages [123], [129], [147], and [151].

Henry Holt and Company for the pictures from Beebe's "The Bird, Its Form and Function" on page [167]; Salisbury's "Physiography" on pages [55], [71], and [167].

Carnegie Institution of Washington for the pictures on pages [8] and [69].

University of Nebraska for the picture on page [37].

Columbia University Press for the picture from Wheeler's "Ants and Their Structure" on page [95].

Houghton Mifflin Company for the pictures from Sharp's "Year Out of Doors" on page [11]; "Riverside Natural History" on page [117]; Mill's "In the Beaver World" on pages [152] and [153].

Ginn and Company for the pictures from Breasted's "Ancient Times" on page [67]; "Agriculture for Beginners" on page [47]; Bergen's "Foundation of Botany" on pages [49], [190], and [197]; Bergen's "Elements of Botany" on pages [193] and [195]; Beal's "Seed Dispersal" on page [51].

U. S. Geological Survey for the pictures on pages [21], [22], [23], [30], [31], and [59].

New York Zoological Society for the pictures on pages [145], [159], and [216].

School Arts Magazine for the picture on page [221].

U. S. Department of Agriculture for the pictures on pages [125] and [189].

American Museum of Natural History for the pictures on pages [20], [24], [26], [139], and [162].

Cassell and Company for the pictures from "Popular History of Animals" on pages [118], [177], [179], and [217]; "Popular Science" on page [242].

Hutchinson for the pictures from "Marvels of the Universe" on pages [92], [101], [103], [141], [169], and [173]; "Marvels of Insect Life" on page [211].

The Dunham Company for the picture on page [45].

International Harvester Company for the picture on page [199].

Northern Pacific Railway for the pictures on pages [235] and [237].

It will be understood, as stated in the preface, that, like "The Strange Adventures of a Pebble," this is an autobiography. In other words, it is the grain of dust itself that tells the story of the life of the soil of which it is a part.

THE ADVENTURES
OF A GRAIN OF DUST

CHAPTER I

(JANUARY)

In truth you'll find it hard to say
How it could ever have been young
It looks so old and grey.

—Wordsworth.

THE LITTLE OLD MAN OF THE ROCK

Some say it was Leif Ericson, some say it was Columbus, but I say it was The Little Old Man of the Rock.

And I go further. I say he not only discovered America but Europe, Asia, and Africa, and the islands of the sea. I'll tell you why.

[I. How Little Mr. Lichen Discovered the World]

As everybody knows, we must all eat to live, and how could either Columbus or anybody else—except Mr. Lichen—have done much discovering in a world where there was nothing to eat? When the continents first rose out of the sea[2] there wasn't anything to eat but rock. Rock, to be sure, makes very good eating if you have the stomach for it, as Mr. Lichen has. It contains sulphur, phosphorus, silica, potash, soda, iron, and other things that plants are fond of, but ordinary plants can't get these things out of the rock—let alone human beings and other animals; and that's why Mr. Lichen had the first seat at the table and always does.

On bare granite boulders in the fields, on the rocky ruins at the foot of mountains, and even on the mountain tops themselves, on projecting rocks far above the snow line, you find the lichens. On rock of every kind they settle down and get to work. They never complain of the climate—hot or cold, moist or dry. When the land goes dry they simply knock off, and then when a little moisture is to be had they're busy again. A little goes a long way with members of the family who live in regions where water is scarce. Indeed, most of them get along with hardly any moisture at all. The very hardiest of them are so small that a whole colony looks like a mere stain upon the rock.

While lichens are generally gray—they seem to have been born old, these queer little men of the rock—you can find some that are black, others bright yellow or cream-colored. Others are pure white or of various rusty and leaden shades. Some are of the color of little mice. To make out any shapes in these tiny forms, you must look very close; and if you have a hand lens you will be surprised to find that this fairy-land of the lichens isn't so drab as it seems to the naked eye. For there are flower gardens—the tiny spore cups. Some of them are vivid crimson and, standing out on a background of pure white, they're very lovely. Some of the science people believe the colors attract the minute insects that the lens shows wandering around in these fairy flower gardens. But just what the insects can be there for nobody knows, since the lichens are scattered, not by insects, but by the wind.

As a rule lichens grow only in open, exposed places, although some are like the violets—they enjoy the shade. Some varieties grow on trees, some on the ground, others on the bleached bones of animals in fields and wastes and on the bones of whales cast up by the sea.

Of course the whole country was awfully wild when the continents first came out of the sea, but that just suited Mr. Lichen, for there is one thing he can't stand, and that is city life, with its smoke and bad air.

"Why, one can't get one's breath!" he says.

WHY THE LICHENS DISLIKE CITY LIFE

So, while you will not meet Mr. Lichen in cities—at least, until after the people are all gone; that is to say, on ruins of cities of the past—you will find him beautifying the ancient walls of abbeys, old seats of learning like Oxford, and the tombstones of the cities of the dead.

Mr. Lichen always travels light. On the surface of the lichens are what seem to be little grains of dust, and these serve the purpose of seeds. A puff of wind will carry away thousands of them, and so start new colonies in lands remote.

You see, the fact that he requires so little baggage must have been a great advantage to Mr. Lichen in those early days, when he had to discover not only America but all the rest of the world map, spread out so wide and far. You can just imagine how the grains of lichen dust, the seed of the race, must have gone whirling across the world with the winds.

But if a breath of wind would carry them away so easily, how could they stay on a rock, these tiny lichen travellers? Especially as they have no roots? They have curious rootlike fibres which absorb food by dissolving the rock, and this dissolved rock, hardening, holds them on. The fibres of lichens that grow on granite actually sink into it by dissolving the mica and forcing their way between the other kinds of particles in the rock that they can't eat. Thus they help break it up.

As we all know, little people are great eaters in proportion to their size, but it is said the lichens are the heartiest eaters in the world. They eat more mineral matter than any other plant, and all plants are eaters of minerals.

Yet, you'd wonder what they do with the food they eat—most of them grow so slowly. A student of lichens watched one of them on the tiled roof of his house in France—one of the kind of lichens that look like plates of gold—and in forty years he couldn't see that it had grown a single bit, although he measured it carefully.

HOW MR. LICHEN EATS UP STONES

But how could such feeble creatures, as they seem to be, ever eat anything so hard as rock? Well, they couldn't if it wasn't for one thing—they understand chemistry. At least they carry with them, or know how to make, an acid, and it's this acid which enables them to dissolve the rock so that they can absorb it. The acid is in their fibres—what answer for roots. And the dissolved rock not only gives them their daily bread, but, as I said a moment ago, holds them on. This use of acid is their way of eating; chewing their food very fine, and mixing it with saliva, as all of us young people are taught to do.

The first and smallest of the lichen family spread and decay into a thin film of soil. This decay makes more acid, just as decaying leaves do to-day—they learned it, no doubt, from the lichens—and this acid of decay also eats into the rock and makes more soil. (You see nature, from the start, has been helping those that help themselves, just as the old proverb has it.) Then, after the first tiny lichens—mere grains of dust that have just begun to feel the stir of life—come somewhat larger lichens which can only live where there is a little soil to begin with. These in turn die, which means a still deeper layer of soil, still more acid of decay, and so on up to larger lichens and later more ambitious plants. Then, on the soil made by these successive generations of lichens, higher types of plants—plants with true roots—get a foothold.

Besides making soil themselves, the lichens help accumulate soil by holding grains of rock broken up by their fibres and loosened by the action of the heat and cold of day and night and change of season. These little grains become entangled in the larger lichens and are kept, many of them, from being washed away by the heavy rains. So held, they are in time crumbled into soil by the action of the acids and by mixture with the products of plant decay. To this day, go where you will, over the whole face of the earth, and you'll find the lichens there ahead of you, dressed in their sober suits, some gray as ashes, others brown, but some are as yellow as gold; for even these old people like a little color once in a while. As travellers they beat all.

"Their geographical range is more extended than that of any other class of plants."

That's how the learned lichenologists put it. For these lichens, these humble little brothers of our dust, that many of us never looked at twice on the stones of the field, or the gray stumps and dead limbs in the wood, are so interesting when you've really met them—been properly introduced—that a whole science has grown up around them called "lichenology." And exciting! You ought to hear the hot discussions that lichenologists get into. You read, for instance, that such and such a theory "was received with a storm of opposition" (as most new theories are, by the way, particularly if they are sound).

But the tumults and the strifes of science, of politics, or of wars don't disturb little old Mr. Lichen himself. There on his rock he'll sit, overlooking the scenery and watching life and the seasons come and go for 100, 200, 500 years, and more. For while they grow so slowly the lichens make up for it by living to an extreme age.

THE LICHENS AND THE ROMAN EMPIRE

Why, do you know that during the lifetime of certain lichens that are still hale and hearty, not only a long line of Cæsars might rise, flourish, die, and, with their clay, stop holes to keep the wind away, as Mr. Shakespere put it, but the vast Roman Empire could and did come into being, move across the stage with its banners and trumpets and glittering pomp and go back to the dust again.

Some lichens, growing on the highest mountain ranges of the world, are known to be more than 2,000 years old!

THE SEQUOIAS; THE SUNLIGHT AND THE SHADE

Wonderful sunlight effect, isn't it? We are here in Sequoia National Park and those big trees are sequoias, members of the pine-tree family.

[II. The March of the Trees]

Of course I don't mean to say it takes any 2,000 years for the average lichen to die and turn to dust. These long-lived lichens are the Methuselahs of their race. Most kinds die much younger, as time goes among the lichens, and in a comparatively few years, a century say, after their first settlement on the rock, the lichens have become soil. All this time the heating of the rock by day and the cooling off at night, the work of frost and the gases of the rain and the air[3] have also helped to make more soil and by and by there is enough for lichens of a larger growth; and mosses begin to get a foothold. These, in turn, die and, in decaying, make acids, as did the little lichens before them, and this acid joins hands with all the other forces to work up the rock into soil. Presently there is enough soil to let certain adventurers of the Weed family drop in. The picking is very thin, to be sure, but some of these Weed people have learned to put up with almost anything. Don't suppose, however, that all weeds are alike in this respect. Oh, dear, no! They come into new plant communities just as the trees do, not haphazard, but according to a certain more or less settled order. Some of them, the adventurer type, will, it is true, settle down and seem contented enough on land so poor that to quote the witty Lady Townshend "you will only find here and there a single blade of grass and two rabbits fighting for that"; while other weeds will have nothing to do with soil that, in their opinion, is not good enough for people of their family connections.

EARLY SETTLERS IN THE DESERT

Besides earning their own living under hard conditions, these sturdy pioneers of the desert are preparing the way for plants of a higher kind, as the next two pictures will tell you.

It has long been known that the character of soil may be told, to a considerable degree, by the kind of weeds that grow on it. An old English writer pointed this out in his quaint way some 200 years ago:

"Ground which, though it bear not any extraordinary abundance of grass yet will load itself with strong and lusty weeds, as Hemlocks, Docks, Nettles and such like, is undoubtedly a most rich and fruitful ground for any grain whatsoever."

But, he goes on to say:

"When you see the ground covered with Heath, Broom, Bracken, Gorse and such like, they be most apparent signs of infinite great barrenness. And, of these infertile places, you shall understand, that it is the clay ground which for the most part brings forth the Moss, the Broom, the Gorse and such like."

Wherever soil is coarse and bouldery the weeds also are of a sturdy breed. In his long, delightful days among the mountains Muir[4] tells us what a brave show the thistles made in this new world of soil; how royal they looked in their purple bloom, standing up head and shoulders above the other plants, like Saul among the people.

WHAT THE DESERT PIONEERS DO FOR FUTURE GENERATIONS

Only the sturdiest kinds of shrubs and weeds, such as you see in the desert, can earn their keep in sandy soil, always thirsty, like that on the right. But the desert vegetation, dying and decaying—it is then called "humus"—not only knits the soil together but absorbs moisture and ammonia from the air and so helps grow good crops.

HOW PLANT PEOPLE PAY THEIR TAXES

In all these plant republics each citizen must pay something into the common treasury for its board and keep. This fund not only meets "national expenses" during the lifetime of the ones who pay these taxes, but it helps prepare the land for the great citizens of the future—the trees. In another hundred years—making two hundred in all, after the arrival of the very first lichens—low shrubs and bushes often find spots in these new communities where the soil is thick enough for their needs.

It is very curious how members of the plant world, growing side by side, seek their food at different depths, and send out their roots accordingly. It reminds one of the rigid class distinctions below stairs in a nobleman's household where the chef has his meals in his own private apartment, the kitchen maids in their quarters, the chauffeurs, footman, under butler, and pantry boys in the servants' hall.

THE LEADERS OF THE GRAND MARCH

But most striking, it has always seemed to me, is the settled order in which trees march into the land. Why shouldn't the oaks come before the maples? Or the maples before the beeches? Or the beeches before the pines? Why is it that, with the exception of a straggler here and there, the first trees to climb the stony mountainsides are the pines? Then close behind come such trees as the poplars, and along the streams below, the willows. Still farther down the valley are the beeches; farther still the maples, and last of all the oaks.

So it is they advance in a certain regular way, each in its own place in the ranks. At first it seems as strange as the coming of Birnam wood to Dunsinane that gave poor Macbeth such a turn that time. But, after all, the explanation is quite simple and no doubt you have guessed it already.

The reason such trees as the pines, poplars, and willows come first is that the seeds are so light they are easily carried by the winds and so reach new soil ahead of other trees with winged seeds like the beeches and the maples; for, although these seeds also travel on the wind, they are much larger than the winged seeds of the pine and they travel much more slowly and for shorter distances.

Moreover, at the end of their first journey, having once fallen to the ground, they are apt to stay. Then there is no further advance, so far as these particular seeds are concerned, until trees have sprung from them and they, in turn, bear seeds. In the case of very light seeds, like those of the pines, the wind not only carries them far beyond the comparatively slow and heavy march of the beech and the maple, but if they fall on rock with little or no soil the next wind picks them up and carries them farther, so that they may strike some other spot where there is soil and perhaps a little network of grass and weeds to secure them until they can take root and so hold their own. It is not only a great advantage to the pine seeds to be so small, so far as getting ahead of other trees is concerned, but it is an advantage in another way. Because they are so small they require comparatively little soil to start with, are more easily covered up, and so they soon begin to sprout. The very winds that carry them up among the mountain rocks are quite likely to cover them with enough dust to start on, and I myself have helped raise many a giant of the mountain forests in this way. It is really wonderful how little soil a pine-tree can get along with; if, say, its fortunes are cast on some mass of mountain rock. Somehow it manages to get a living among the cracks and at the same time to hold its own in the bitter struggle with the winds.

"The pine trees," says Muir, "march up the sun-warmed moraines in long hopeful files, taking the ground and establishing themselves as soon as it is ready for them."

From the painting by Rousseau in the Metropolitan Museum of Art.

THE EDGE OF THE WOODS

Last of all come tramping along the sturdy old oaks.

Last of all come tramping along the sturdy old oaks and the nut-bearing trees. Their seeds are so heavy they get little help from the winds, and then only in the most violent storms. They must advance very slowly indeed, with occasional help from absent-minded squirrels who carry away and bury nuts and acorns and then forget where they put them.

HOW SQUIRRELS HELP OAKS TO MARCH

Sometimes they bury acorns and forget just where. When frightened they often drop them and run away.

ROUGH CITIZENS AMONG THE PIONEERS

The beginnings of a forest are stunted because the soil is thin. Moreover, the company in which the trees find themselves is very miscellaneous, like the population of all pioneer communities—weeds, grasses, briers, shrubs. High up on a mountainside you can find all these types of vegetation. Pines growing clear to the snow line; farther down the mountain, in crannies, sumach and elder bushes with field daisies and goldenrod scattered among them; while on the barren rocks are the lichens and the mosses.

Not only do the citizens of the plant world follow a certain fixed order in coming into new regions, but also in giving place to one another. All plants of a higher order can live only on the remains of those of a lower, and it is most interesting to note the process by which each lower form comes, does its work, passes on, and is replaced by a superior type. The shrubs, which can only grow after the weeds and grasses have made enough soil for them, at length shade out these smaller pioneers. Haven't you often noticed, when picnicing in deep woods, that the grasses and flowers are to be found only in the sunny spaces, where there are no trees?

But these thickets themselves, after a while, disappear, and pines take their places. I am speaking now of the growth of forests, where the soil-making has so far advanced that forests are possible. The thickets, with their good soil and the shade which keeps it damp, are just the places for the pine seeds brought in by the wind to get a foothold and sprout up. When they grow into big trees they gather with their high branches so much of the sunshine for themselves that little of it gets through to the shrubs below, so these shrubs disappear, surviving only in the sunny open spaces or along the borders of the wood.

But now notice what happens to the pines. When the trees become larger, the young pines that spring up beneath their shade can't get enough sunshine, so, as the big trees grow old and die, there are fewer and fewer young pines to take their places. Now comes the turn of the spruces. For spruces require more and better soil than the pines and they don't mind a reasonable amount of shade. So, as the woods grow thicker and shadier, the pines gradually disappear and the spruces take their places.

At first, in the reign of the spruces, some of the old residents begin to come back. A spruce forest, not being so dense in the beginning as a pine forest, lets in a good deal of sunlight, and you'll find scattered through its aisles and byways gentians, bluebells, daisies, goldenrod.

In course of time, however, the leaves and branches of the spruces become so thick that hardly a sunbeam can get through and you have a forest where noontime looks like twilight; a forest of deep shade and silence with its thick carpet of brown needles, and where all the shrubs and grasses and flowers have disappeared, except in the open spaces. It was in such a forest and in one of these sunny glades, no doubt, that the knight the little girl tells of in Tennyson:

"... while he past the dim lit woods
Himself beheld three spirits mad with joy
Come dashing down on a tall wayside flower
That shook beneath them as the thistle shakes
When three gray linnets wrangle for the seed."

[HOW NATURE RESTORES ABANDONED FARMS]

So it is that new lands pass from barren rock to forest, and deep rich soil, and so it is that worn-out soils, the result of reckless farming are finally restored. Hardly any soil is too poor for some kind of a weed. These weeds springing up, die and make soil that better kinds of weeds can use. Later come a few woody plants. In the course of fifteen or twenty years the soil is deep enough to support trees; and in fifty years there is a young forest. At the end of a century fine timber can be cut, the land cleared, and the old place may be as good as new.

But it's a long time to wait! It's a much better plan to take care of the land in the first place.

HIDE AND SEEK IN THE LIBRARY

One of the strangest things about Mr. Lichen, as you will see by looking up the subject in any botany or encyclopædia, is that he is really two people—two different plants that have grown into partnership; and that one of the partners supplies water for the firm while the other furnishes the food.

The part of "him" that supplies the food is green, or blue-green, and that is why it is able to do this. This idea that Mr. Lichen is really two people was one of those that was "received with a storm of opposition," but certain lichenologists actually took two different kinds of plants, put them together and made a lichen themselves, as you will see when you look the matter up.

As to just who among these two kinds of plants shall go into partnership—that usually depends on chance and the winds; although in the case of some lichens, the parents determine upon these partnerships, just as they often do in human relations.

If you want to continue this interesting study and become Learned Lichenologists, you will be interested to know that there are a lot of things to be learned, including not only no end of delightful names, such as Endocarpon, Collema, Pertusaria, not to speak of Xanthoria parietina, and loads of others, but there are still things unknown that you may be able some day to find out. For instance, while they know that the two kinds of vegetation that together make a lichen, feed and water each other, it's not known exactly how they do it; although the "Britannica" article has a picture showing the two partners in the very act of going into partnership. The article in the "Americana" shows some striking forms of lichens, and how nature from these very dawnings of life begins to dream of beauty. You will be surprised at the forms shown in the "Americana," they are either so graceful, symmetrical, or picturesque. One of them looks like a very elaborate helmet decoration, or plume of a knight.

This article also tells what an incredible number of species of lichens there are—enough to make quite a good-sized town, if they were all real people.

It also tells why the orange and yellow lichens take to the shady side of the rock; and something about how the lichens get those remarkable decorations and sculpturings, and what the weather has to do with it.

There you will also get a probable explanation of the fact that the manna which the Israelites found on the ground in the morning appeared so suddenly.

In the article in the "International" you will find another picture of how the two partners—the fungus and the alga—make the lichen, and you will learn that Mr. Lichen's name, like Mr. Lichen himself, is centuries old; being the very name given him by the Greeks, and afterward by the Romans.

In the "Country Life Reader" there is an article on the soil that has a very close relationship to the subject of the lichens and their work. It tells, among other things, about the value of humus—decayed leaves, grass, etc.—to the soil. It was the lichens, you know, who started the humus-making business.

The article in the reader on "Planting Time," by L. H. Bailey, expresses the wonder we must all feel when we stop to think about it, at the magic work of the soil in changing a little speck of a seed into a plant.

CHAPTER II

(FEBRUARY)

Behold a strange monster our wonder engages!
If dolphin or lizard your wit may defy.
Some thirty feet long, on the shore of Lyme-Regis
With a saw for a jaw and a big staring eye.
A fish or a lizard? An Ichthyosaurus,
With a big goggle-eye and a very small brain,
And paddles like mill-wheels in chattering chorus
Smiting tremendous the dread-sounding main.

—Professor Blackie.

SOME EARLY SETTLERS AND THEIR BONES

But a farm where nothing but plants grow isn't much of a farm. Every good farmer knows that nowadays, and so he stocks his place with horses and cows and chickens and things. Mother Nature understood this principle from the beginning, and the plants and animals on her farm have always got on well together.

For one thing the plant and the animal each help the other to get its breath. That is to say, plants, when they take in the air, keep most of the carbon there is in it and give back most of the oxygen, which is just what the animal world wants; while the animals, when they breathe, keep most of the oxygen and give back most of the carbon—just the thing that plants grow on.

But the service of the animals to the plants is very important after they have stopped breathing altogether; since their flesh and bones, like the dead bodies of the plants, go back to enrich their common dust. The bones and bodies and shells of members of the animal kingdom, however, are far richer food for soils than is dead vegetation. The shell creatures of the sea to which we owe our wonderfully fertile limestone soils are—many of them—so small that you can only make them out with a microscope; while certain other contributors to our food-supply were so big that one of them, walking down a country road, would almost fill the road from fence to fence.

I. Mr. Dinosaur and His Neighbors

A STRANGE FACE IN THE MEADOW

Now let's take a look at some of these big fellows. How would you like to have such a creature as the one at the right of this page come ambling up to meet you at the meadow gate of an evening when you went to milk the cows? Yet more than likely either this gentle animal, or some of his kin, browsed over the very field where now the cattle pasture, for he, too, was a grass-eater, and with an appetite most hearty. If you kept him in a barn his stall would have to be eighty feet long, and it would be necessary to fill his rack with a ton of fodder every third day. But, assuming there was a market for him in the shape of steaks and roasts, you would be well repaid; for, in prime condition, he weighed twenty tons.

IN THE LAND OF HIS FATHERS

These monsters who ate grass, and other monsters who ate them, and still other monsters who lived in the sea, appeared comparatively late in the life of the world.

NO WONDER HE NEVER WORRIED!

Quite aside from the fact that he had so little brain to worry with, it seems highly improbable that the Stegosaurus ever felt any apprehension about attacks from the rear, in the frequent military operations which distinguished the times in which he lived. In addition to the horny plates down his back he had those horny spines which were swung by a tail some ten feet long.

TONS AND TONS OF ANCIENT BONES

It is only about 15,000,000 years ago, for example, that the biggest of them all, the Dinosaurs, lived, while the earth itself is now supposed to be some 100,000,000 years old. Their numbers were enormous, and it is probable there is not an acre of ground from the Atlantic to the Pacific, and from Alaska to the tip end of South America that has not been fertilized by their bones. In fact, of certain species I have found the bones scattered all the way from Oregon to Patagonia; so this must have been their pasture.

They were not only all over the land, but in the lakes and in the great sea that once extended right through North America from the Gulf of Mexico to the Arctic Ocean. And they were along the shores of the sea and in the swamps. The bones of the ancestors of the whale were found in such quantities in some of the Southern States that they were used to build fences until it was found they were much more valuable to enrich the fields themselves.

THE HEAD OF HESPERORNIS

"Then there was a great toothed, diving creature with wings. They've named him the Hesperornis, which means 'western bird,' because the fossils of the best-known species were found in the chalk-beds of Kansas."

In the great American inland sea of those days swam one kind of fierce fish-lizard that took such big bites he had to have a hinge in his jaw. Because of this hinge he could open his mouth wider without putting anything out of place, don't you see? He was called the Mesosaur. But he never bit the Archelon, who was in his crowd, because he couldn't. The Archelon was the king of turtles, and, like all the turtle family, wore heavy armor. He was over twelve feet long. And sharks—no end of them! A shark at his best is bad enough, but the sharks of those days were almost too terrible to think about. Such jaws! And teeth like railroad spikes! Then there was a great toothed diving creature with wings. They've named him the "Hesperornis," which means "western bird." He was given the name because the fossils of the best-known species were found in the chalk-beds of Kansas.

GREATEST OF ANCIENT FLYING MACHINES

Mr. Pterodactyl, on his way to dinner, looked like this. He was the largest of all flying-machines before the days of the Wright brothers. He would have measured—if there had been anybody to measure him—twenty feet across the wings! Like the Hesperornis, he always dined on fish.

Over the waters flew another bird-like, fish-like, bat-like thing called the Pterodactyl. Look at his picture and you will see how he got his nickname. It means "finger-toe." He was the largest of all flying-machines until the days of the Wright brothers. It was over twenty feet across his wings, from tip to tip; and, like the Hesperornis, he always had fish for dinner.

A BIG "LITTLE FINGER" AND WHAT IT WAS FOR

Mr. Pterodactyl means "finger toe." What is our little finger was the longest of his five digits. It helped support and operate that big bat-like wing extending from his arms to his toes.

THE EARLIEST RULERS OF THE SEA

The first monsters, like the first of almost everything else, including the land itself, were in the sea.[5] For a time giant fish, armor-plated like a man-of-war, and with awful appetites, just about ran everything. Then came the reign of the sharks. Some of them had jaws that opened to the height of a door—six feet or over. Next in succession, as rulers of the sea, were the fish-lizards, of whom that hinge-jawed Mesosaur was one. Of another of these fish-lizards a famous teacher of Edinburgh University, Professor Blackie, wrote that funny verse at the head of this chapter. The bones of this particular specimen were found sticking out of a cliff at Lyme-Regis, a popular watering-place in the English Channel, by a pretty English girl who was strolling along the beach.

A FAMILY PARTY

The imagination of the artist enables us to picture this family party—Mrs. Ichthyosaurus and her children out for a stroll in prehistoric waters.

The Ichthyosaurus, as Professor Blackie says in his verse, was some thirty feet long, with a comparatively large head—like an alligator's—set close to his body. Another fish-lizard, well and unfavorably known by his neighbors of the sea, was the Plesiosaurus. Instead of fins he had big paddles resembling those of the seal. He was a kind of side-wheeler, like the Mississippi River steamboats, and he could go like everything! His neck was long and he darted after the smaller creatures he lived on.

[REIGN OF THE LIZARD FAMILY]

But these queer fish seem to have just been getting ready to land; for, by being lizards, they after a while managed it. A lizard, you know, belongs to the reptile family, and out of these sea reptiles there grew, in course of time, reptiles which lived, not in the sea but in the swamps along the sea. These reptiles were the Dinosaurs, and they are related to the Minosaurs and the Ichthyosaurus, and the rest of the Saurs, as you can see by the family name; for "saur" means lizard. Dinosaur means "terrible lizard." Don't you think he looks it?

Although some of these Dinosaurs were no larger than chickens, others were by far the largest creatures that ever were, on sea or land. Many of the biggest lived on grass, just like an old cow, while the flesh-eating Dinosaurs lived on them. Some of these Dinosaurs went on all fours, while others ran about on their hind legs, and when they stood still, propped themselves up on their big, thick tails as do kangaroos. The Camptosaurus, one of whose favorite resorts was the land that is now Wyoming, was thirty feet long. Another called the Brontosaurus, was sixty feet long. The Atlantosaurus, one of the pioneers of Colorado, measured eighty feet from the end of his nose to the end of his tail, and all of them were built in proportion. The Stegosaurus, also an early settler in Wyoming, had huge bony plates, like ploughshares, sticking out all along his back from the nape of his neck to the end of his tail. He seems to have gone about looking quite ugly and humpbacked, as our old cat does when she has words with the dog.

After the swamps dried up and the lizards could no longer make a living, came the reign of the mammals; including the Mastodons and the Mammoths, marching in countless herds, trumpeting through the forests.

HOW SOME MONSTERS PLOUGHED THE FIELD

But besides what they did in the way of fertilizing the land with their flesh and bones some of the mammals did a good deal of ploughing. Among these early ploughmen were the Mastodons and the Mammoths, and another elephant-like creature with two tusks, that he wore, not after the fashion among elephants to-day, but curving down from his chin, somewhat like Uncle Sam's goatee. He used these tusks, it is supposed, not only for self-defense, but for grubbing up roots which he ate. If so, they must have been about as good ploughs as those crooked sticks that were used by the early farmers among men, and that are still in use among primitive peoples.

[THE ELEPHANT FAMILY AS PLOUGHMEN]

What makes it more likely that the creature with the down-curving tusks stirred the soil with them is that his cousins, the elephants of to-day, are themselves great ploughmen. Elephants feed, not only on grass and the tender shoots of trees, but on bulbs buried in the soil, which they hunt out by their fine sense of smell. In digging these bulbs they turn up whole acres of ground. Elephants also do a great deal of ploughing by uprooting trees so as to make it more convenient to get at their tender tops. Sir Samuel Baker, the explorer, says the work done by a herd of elephants in a mimosa forest in this way is very great and that trees over four feet in circumference are uprooted. In the case of the biggest trees several elephants work together, some pulling the tree with their trunks, while others dig under the roots with their tusks. To be sure, the mimosa-trees have no tap roots, but tearing them out of the ground is no small job, nevertheless. It takes strength and it takes engineering.

Another early ploughman was a bird, the Moa. The Moa had no wings, but his muscular legs were simply enormous, and so were his feet. New Zealand seems to have been the headquarters of the Moas. There used to be loads of them as shown by the huge deposits of their bones. They are supposed to have been killed in countless numbers during the Ice Ages in the Southern Hemisphere; for there were Ice Ages in the Southern as well as the Northern Hemisphere. In one great morass in New Zealand abounding in warm springs, bones of the Moas were found in such countless numbers, layer upon layer, that it is thought the big birds gathered at these springs to keep warm during those great freezes.

THE MILLSTONES OF THE MOAS

Besides the work they did with feet and bills you may imagine how much nice fresh stone the Moas must have ground up in their crops during the millions of years they existed. It was a regular mill—the gizzard of a Moa—full of pebbles as big as hickory nuts. Scattered about the springs where their bones are found are little heaps of these pebbles, each the contents of a gizzard. Like miniature tumuli, they mark the spots where the bodies of the Moas returned to dust.

Perhaps some of those flesh-eating Dinosaurs did a little ploughing once in a while, too; for one theory is that those ridiculous little arms were used for scratching out a nest for the eggs, just as the crocodiles and the alligators and the turtles dig nests for their eggs to-day. For all these animals, as did the Dinosaurs, belong to the reptile family, and show the family trait of digging out nests for their eggs.

A PUZZLE PAGE FROM THE GREAT STONE BOOK

Talk about your cut-out puzzles! Here is a specimen of the kind of puzzle Nature and the course of things in the darkest ages of world history have cut out for the paleontologists. It is a find of ancient bones in the asphalt deposits near Los Angeles.

Although the Dinosaurs roamed the swamps and lowlands of all the ancient world, their favorite resort was the territory now occupied by our Western States—judging from the quantities of bones they left—while that old Mediterranean Sea of ours was full of their kin, the sea-lizards. Professor Marsh, of Yale, who was among the first explorers of the graves of these monarchs of the past, says that one day, while riding through a valley in the Rocky Mountains, he saw the bones of no less than seven sea-lizards staring at him from the cliffs. Yet, only here and there by the wearing through of the rocks by flowing streams has nature opened up these vast mausoleums, the mountains and the cliffs. What enormous quantities of bones, then, must still be buried there, what tons and tons must have given their lime and phosphate to the soil. So you see this story of old bones, even from a farming standpoint, is no light matter.

HOW THE WISE MEN ANSWER THE PUZZLES

By their marvellous skill and their knowledge of the mechanics of monster anatomy the paleontologists fit one bone fragment to another, supply the missing parts in artificial material, and behold! the monsters take their places in the long procession of the ages. There has been nothing equal to it since the vision of the prophet in the Valley of Dry Bones. (Ezekiel 37:1-10.)

II. How the Monsters Died and Returned to Dust

"But you said these monsters lived in the sea and in swamps. Then how, in the name of common sense, did their bones get up into the mountains?"

WHEN THE INLAND SEA WENT DRY

Well, it's like this: As I said a while back, in the days of the monster fish and the monster lizards, there was a great sea reaching clear from the Gulf of Mexico to the Arctic Ocean, and with swamps along the borders extending far into lands that afterward became the Rocky Mountains. When the land began to rise, due to the shrinking of the earth—a thing that has been going on ever since the earth was born—the sea and the swamps went dry, and far to the west the land wrinkled up into the Rocky Mountains. In these layers of rock that made the mountains were the bones of the monsters that had died when the rocks were still mud, in the swamps and along the borders of the inland sea.

Not only did the land under the western portion of the sea slowly rise until the waters were completely closed in on the west, and the sea thus made that much narrower, but the rise of the land on the south cut off connection with the great salt ocean which surrounds the continents to-day. So the salt-water fish, for lack of salt water, died, and with them the monsters like the Ichthyosaurus that lived on the salt-water fish that lived in this salt sea.

But it wasn't alone that the seas grew narrower and more shallow because of the elevation of the lands. The mountains rising in the west, cut off the rain-laden winds which blew from the Pacific in those days just as they do now. Thus the seas dried up so much the faster. But first, before the sea went entirely dry, its place was taken by the lakes and swamps into which it shrivelled up. Low, swampy land is just what reptiles like, so this was their Golden Age, just as the previous time of the wide, deep sea was the Golden Age of the big fish and the fish-lizards.

Then, as the land still rose and the climate grew dryer, the reptiles passed away, and in came the mammal family, to which the cows and the horses and the cats and the kittens, and all the rest of us, belong.

THE TIGER WITH THE SABRE TEETH

Tigers like this lived ages ago in both the Old World and the New. They had canine teeth, curved like a sabre, in the upper jaw.)

TOO MUCH BRAWN, TOO LITTLE BRAIN

Of course, even where they didn't die with their boots on, so to speak, as so many of them did in those lawless days, there came a time for each monster, in the order of nature, when he drew his last breath. But what seems so strange is that all these monsters—the biggest and strongest of them—entirely disappeared and left no descendants![6] The whole of the mystery has not been unravelled yet, even by the wise men of science, but still they have learned a good deal. For one thing, they know that most of the reptiles and the fish-lizards disappeared because so much of the land where they lived went dry. They had to get a new boarding-place, and there wasn't any to get! Another thing was that these big fellows, although they were so big, and got along finely while everything was just so, had so little brain they couldn't change their habits to meet new conditions, as our closer and cleverer cousins, the mammals, did. Why, do you know that one of these monsters, who was twenty-five feet long if he was an inch, and twelve feet high, had a brain no bigger than a man's fist? All the monsters of those days were like that—tons of bone and muscle, but a very small supply of brains.

So when things went against them, they just had to give up, and, like a queer dream, they faded away. But their history makes one of the most interesting chapters in the whole wonderful story of the dust.

Of all the live stock that have fed on the great world-farm and helped enrich it with their bones, these animals were surely the strangest that ever were seen!

[HIDE AND SEEK IN THE LIBRARY]

"But since these monsters passed away many millions of years ago, and all that is usually found is a piece of them here and there, how do the men of science know so much about them—how they looked, and how they ate, and how they treated one another?"

That's a good question. It does seem strange. Why, to hear them talk, you'd suppose these men, learned in ancient bones, had actually met the monsters! And, speaking of meeting them, I must tell you a little story. It's a good story and it will answer your question.

Baron Cuvier, one of the most famous of the paleontologists, awoke from a deep sleep to see standing by his bed a strange, hairy creature with horns and hoofs. And it said:

"Cuvier! Cuvier! I have come to eat you!" But the baron, taking in the form of the monster at a glance, only laughed.

"Horns and hoofs? You can't. You're a grain-eater!"

See the point? The baron argued that because the monster had horns and hoofs he must be a grain-eater; for all creatures with both horns and hoofs are grain-eaters. This particular creature, to be sure, was an eater of both meat and grain—being one of Cuvier's students who was trying to play a trick on him. But the principle holds good. The scientists, knowing one thing, infer another. Because animals with both horns and hoofs eat no meat Cuvier knew his visitor couldn't eat him, even if he'd been real and not just made up.

For another instance, take our queer old friend that Professor Blackie wrote the funny rhyme about—the Ichthyosaurus "with a saw for a jaw and a big staring eye." The scientists figure, just from looking into the hollow socket where the eye used to be, that he could see at night like a cat—and right through muddy water, too; that he spent most of his time in shallows near the shore; that it didn't make any difference to him whether a fish was near or far, provided it wasn't too far, of course, for he could see it and catch it, just the same. They also said—these learned men, after peering into the dark hollow where that remarkable eye used to be—that Mr. Ichthyosaurus spent a great deal of time diving and a great deal of time with his homely face just above the surface of the water.

Why they could reason all this from a hollow eye socket and some bony, flexible plates around the outer edge of it, you will see by referring to such books as "Animals of the Past," by F. A. Lucas, director of the American Museum of Natural History; "Creatures of Other Days" and "Extinct Monsters," by Hutchinson; "Extinct Animals," by Lankester; "Mighty Animals," by Mix; the chapter "When the World was Young," in Lang's "Red Book of Animal Stories," and "Restoring Prehistoric Monsters" in "Uncle Sam, Wonder Worker," by Du Puy.

Here are some more conclusions they draw from certain facts. See how near you can come to reasoning them out for yourself before looking them up in the books that tell.

Why it is supposed the Dinosaurs swam like Crocodiles. (Look at the picture of Mr. I., and pay particular attention to his tail.)

Why it is they say that the sea-lizards with long necks must have had small heads.

Why it is argued that because the Mesosaurus had a hinge in his jaw he must have had a big, loose, baggy throat.

"Keeping Up the Soil," in "The Country Life Reader," deals with the subject of the use of fertilizers on the farm—how easy it is to waste them, how easy it is to save them, and how important it is that they should be saved; while the article on "Acid Soils" tells how the lime in the bones of the monsters has helped keep the soil from getting "sour stomach," and also how they unlocked the potash and phosphorus in the soil so that the plants could get at them.

FERTILE FIELDS THAT RODE ON THE WIND

The winds that now help grow the corn and wheat on these broad fields by carrying the pollen from one plant to another, also brought the soil on which they grew. These are the loess plains of Nebraska. There are 42,000 acres of them.

CHAPTER III

(MARCH)

... the busy winds
That kept no intervals of rest.

—Wordsworth.

—Tusser.

THE WINDS AND THE WORLD'S WORK

That saying "idle as the winds" must have started in the days when they didn't know; for if ever there was a busy people, it's the Winds.

Not only do they help plant the trees of the forest, sow the fields with grass and flowers, and water them with rain, but they make and carry soil all over the world. And, like everything else in Nature, they have a sense of beauty and the picturesque. Rock, for example, weathered away into dust by the help of the winds, as it is, takes on all sorts of picturesque shapes. And, of course, the winds love music; everybody knows that. Before we get through with this chapter we're going to end a happy day outdoors with a grand musical festival in the forest, with light refreshments—spice-laden winds from the sea. There'll be nobody there but the trees and the winds and John Muir and us; all nice people.

I. Such Clouds of Dust!

March leads the procession of the dusty months because the warming up of the land, as the sun advances from the south, brings the colder and heavier winds down from the north. These winds seem to have a wrestling match with the southern winds and with each other, and among them they kick up a tremendous dust, because there's so much of it lying around loose; for the snows have gone, and the rainy season hasn't begun, and the fields are bare.

ABOUT THE DUST WE GET IN OUR EYES

Most people think these March winds a great nuisance because some of us dust grains are apt to get into their eyes; but dust in the eye is only the right thing in the wrong place. Just think of the amount of dust going about in March that doesn't get into your eye; and how nice and fine it is, and how mixed with all the magic stuff of different kinds of soil, thus brought together from everywhere.

An English writer on farming says he thinks the fact that English farms have done their work so well for so many centuries is due, in no small degree, to the March winds that have brought us world-travelled dust grains from other parts of the globe.

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!

II. The Dust Mills of the Wind

But wind is not alone a carrier for other dust-makers; it has dust mills of its own. The greatest of these mills are away off among the mountains and in desert lands, but after making it in these distant factories the winds carry much of this fresh new soil material to lands of orchard and pasture and growing grain.

Not long ago two of the professors at the University of Wisconsin found a good illustration of what an immense amount of soil is distributed in this way, and what long distances it travels. Among the weather freaks of a March day was a fall of colored snow that, it was found, covered an area of 100,000 square miles, probably more. The color on the snow was made by dust blown clear from the dry plains of the Southwestern States, a thousand miles away. The whole of this dust amounted to at least a million tons; and may even have amounted to hundreds of millions of tons, so the professors think.

TYPES OF NATURE'S SCREW PROPELLERS

You can see for yourself (from the picture on the left) that long before man ever thought of driving his ships through the water with screw propellers or pulling his flying machines through the air by the whirligigs on the end of their noses, some flying seeds, such as those of the ash here, had screw propellers of their own. And do you know that Nature also employs the propeller principle, not only in the operation of the wings of birds but in the wing feathers themselves? The two pictures on the right show the action of the wing and the wing feathers when a bird is in flight.

LITTLE MILLSTONES IN BIG BUSINESS

For grinding rocks to get out ore, or for making cement in cement mills, men use big machines, somewhat on the style of a coffee-mill. These machines are called "crushers." The winds, in their enormous business of soil-grinding, however, stick to the idea you see so much in Nature, that of using little things to do big tasks; as in digging canyons and river beds, and spreading out vast alluvial plains by using raindrops made up into rivers; in working the wonders of the Ice Ages with snowflakes; and building the bones and bodies of those big early settlers, and of all animal life, and the giant trees of the forest out of little cells. For, what do you suppose the winds take for millstones in grinding down the mountains into dust? Little grains of sand!

And with the help of the sun and Jack Frost it makes these fairy millstones for itself. The outside of a big rock grows bigger under the warm sun, in the daytime, and then when the sun goes down and the rock cools off it shrinks, and this spreading and shrinking movement keeps cracking up and chipping off pieces of rock of various sizes. Up on the mountain tops, among the peaks, the change of temperature between night and day is very great, and even in midsummer you can always hear a rattling of stones at sunrise. The heat of the rising sun warms and expands the rock, and so loosens the pieces that Jack Frost has pried off with his ice wedges during the night.

Then also during periods of alternate freezing and thawing in Spring and Fall, the rock is slivered up. These changes in the weather as between one day and another are due to the winds. In January and February, for example, thaws and freezes are common. When the winds blow from the south, the snow melts, water runs into cracks in the rock and fills their pores; then a shift of the winds to the north, a freeze, and the water in the crevices and the pores turns to ice, expands, and breaks off more rock.

And what muscles Jack has! Freezing water exerts a pressure of 138 tons to the square foot; so there's no holding out against him once he gets his ice wedges in a good crack. He sends huge blocks tumbling down the mountainside. The larger blocks, striking against one another, break off smaller fragments. The smallest fragments the wind seizes. Others are washed down by the rains. The largest, carried away by mountain torrents, bump together as they thunder along, and so break off more fragments and grind them so small that the wind can pick them up along the banks when the torrents shrink, or in their beds when these sudden streams go dry.

RUNNING WATER AND THE WINDS

In changing rock into soil, running water and the winds each have an advantage over the other. Water weighs a great deal more than air—over 800 times as much—and so grinds faster with its tools of pebbles and sand. The winds, on the other hand, get over a great deal more territory, and they, like the lichens, understand chemistry. Two of the gases they always carry right with them—carbon dioxide and oxygen—help decay the rocks.

As I said, the winds do most work in dry and desert regions, but when you remember that over a fifth of the globe is just that—dry as a bone most of the time—you see this is a great field. It has been so from the beginning, for it is thought probable that there was always about the same proportion of desert lands. Night and day the winds have been busy through all these ages. Dust is carried up by ascending air currents. Then the same force that keeps the earth in its orbit—gravity—pulls down on a grain of dust. But its fall is checked by the friction of the air. You see there's a lot of mechanics involved in moving a grain of dust; and Nature goes about it as if it were the most serious business in the world; handles every grain as if the future of the universe depended on it. In the case of sand or coarse dust, unless the winds are very strong, gravity soon gets the best of it, and down the dust grain comes to the ground again; then up with another current, then down again—carried far by stiff breezes, only a short distance by puffs—a kind of hop, skip, and jump. But fine dust getting a good lift into the upper currents at the start may stay in the air for weeks.

Courtesy of The Dunham Company.

TO KEEP MOISTURE AND SOIL AT HOME

In the broad fields of the West, where "dry-farming" is practised, they have these huge machines. They are called "Cultipackers." They are cultivators with big, broad-brimmed wheels that pack the surface of the soil after the blades of the cultivator have stirred it. This not only prevents the moisture in the soil from evaporating as fast as it would otherwise do, but keeps the winds from carrying away the soil itself.

In very wild wind-storms it has been figured out that there may be as much as 126,000 tons of dust per cubic mile; several good farms in the air at once, over every square mile of the earth below!

III. The Storm Ploughs of the Wind

TWO KINDS OF WOODEN PLOUGHS

They use wooden ploughs, these winds, just as primitive man did, and as primitive peoples do now; but not quite in the same way, and the ploughing they do is much better. For man's wooden plough is a crooked stick made from the branches of a tree while the winds use the whole tree—roots and all, and both on mountainsides and on level lands the amount of ploughing they do is immense.

Almost all forests are liable to occasional hurricanes which lay the trees over thousands of acres in one immense swath. A large number of these trees, owing to their strong trunks, do not break off but uproot, lifting great sheets of earth. Soon, by the action of its own weight and the elements, this soil falls back. The depth to which this natural ploughing is done depends, of course, on the character of the tree, but as it is the older and larger trees that are most likely to be overturned, since they spread more surface to the wind, the ploughing is much deeper than men do with ordinary ploughs.

The result is that new unused soil is constantly being brought to the surface; and not only this, but air is introduced into the soil far below the point reached by ordinary ploughing. The soil needs air just as we do; for the air hurries the decay of the soil and its preparation for the uses of the plant. The immediate purpose of ploughing is to loosen the soil so that the roots of the plants can get their food and air more easily. It also helps to keep the fields fertile by exposing the lower soil to more rapid decay.

But here's the trouble: While the ordinary plough introduces air into the soil for a few inches from the surface, the subsoil, which is very important to the prosperity of the plant, is practically left out of it, so far as getting needed fresh air is concerned. The long roots of the trees that, among other things opened for it channels to the air, are gone. The burrowing animals that used to loosen up the earth, man has driven away. More than that, the foot of the plough which has to press heavily on the subsoil in order to turn the furrow, smears and compacts the earth into a hard layer, which shuts out the air, and also—to a certain extent—the water from the lower levels.

HOW THE SOIL GETS ITS BREATH

Plants must have air to breathe, both above and below the soil, and the microscope is showing us here how a sandy loam allows the air to reach the roots.

In mountain regions these "storm ploughs," as we may call them, not only help to renew and prepare the soil in the valleys, but are a part of the machinery of delivery of new soil from mountain to valley. When trees on the mountainside are overturned, they not only bring up the soil, which the mountain rains quickly carry to the valleys, but the roots having penetrated—as they always do—into the crevices of the rocks, bring up stones already partly decayed by the acids of the roots. These stones, as the roots die, decay and so release their hold, and also go tumbling down toward the valley.

Consider how much of this storm-ploughing must be done in the forests of the world in a single year, and that this has been going on ever since trees grew big on the face of the earth. In a storm in the woods of California, Muir heard trees falling at the rate of one every two or three minutes. And, as I said, it is precisely the trees that can do the most ploughing—the older and larger trees—that are most apt to go down before the wind. Younger trees will bend while older and stiffer trees hold on to the last. Before a mountain gale, pines, six feet in diameter, will bend like grass. But when the roots, long and strong as they are, can no longer resist the prying of the mighty lever—the trunk with its limbs and branches—swaying in the winds, down go the old giants with crashes that shake the hills. After a violent gale the ground is covered thick with fallen trunks[7] that lie crossed like storm-lodged wheat.

There are two trees, however, Muir says, that are never blown down so long as they continue in good health. These are the juniper and dwarf pine of the summit peaks.

"Their stout, crooked roots grip the storm-beaten ledges like eagle's claws, while their lithe, cord-like branches bend round completely, offering but slight holds for winds, however violent."

AT THE STORM FESTIVAL WITH MR. MUIR

Trees were among Muir's best friends, and he spent a large part of his life chumming with them. What do you think that man did once? He was always doing such things. He climbed a tree in a terrific gale so that he could see right into the heart of the storm and watch everything that was going on. Just hear him tell about it:

"After cautiously casting about I made choice of the tallest of a group of Douglas spruces that were growing close together like a tuft of grass, no one of which seemed likely to fall unless the rest fell with it. Being accustomed to climb trees in making botanical studies, I experienced no difficulty in reaching the top of this one, and never before did I enjoy so noble an exhilaration of motion."

And such odors! These winds had come all the way from the sea, over beds of flowers in the mountain meadows of the Sierras; then across the plains and up the foot-hills and into the piny woods "with all the varied incense gathered by the way."