(MARCH)
... the busy winds
That kept no intervals of rest.
--_Wordsworth._
Except wind stands as never it stood
'Tis an ill wind turns none to good.
--_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.
[Illustration: 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.
[Illustration: _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.
[Illustration: 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.
[7] Muir: "Mountains of California."
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."
[Illustration: THREE KINDS OF SEED THAT THE WIND SHAKES FREE
Here are three kinds of seed adapted for dispersal by the shaking action
of the wind.]
Though comparatively young, these trees--the one Mr. Muir climbed into
and its neighbors--were about 100 feet high, and "their lithe, brushy
tops were rocking and swirling in wild ecstasy." In its greatest sweeps
the top of Muir's tree described an arc of from twenty to thirty
degrees, but he felt sure it wouldn't break, and so he proceeded to take
in the great storm show.
"Now my eye roved over the piny hills and dales as over fields of
waving grain, and felt the light running in ripples across the
valleys from ridge to ridge, as the shining foliage was stirred by
the waves of air. Oftentimes these waves of reflected light would
break up suddenly into a kind of beaten foam and finally disappear
on some hillside, like sea waves on a shelving shore."
This was his impression of the forest as a whole, a dark green sea of
tossing waves. But if we study trees as long and lovingly as Muir did,
we can pick out the different members of the family a mile away--even
several miles away--by their gestures, their style of grave and graceful
dancing in the wind.
[Illustration: TYPES OF FLYING MACHINE
Here is the type of flying machine that carries men. On the opposite
page is the kind that carries the dandelion seeds.]
[Illustration: THE DANDELION-SEED FLYING MACHINE
The dandelion on the left shows how the seeds are kept in the "hangar"
at night and on rainy days, shut up tight to prevent them from getting
wet with rain or dew and so made unfit for flying.]
Muir especially mentions the sugar-pines as interpreting that storm to
him. They seemed to be roused by the wildest bursts of the wind music to
a "passionate exhilaration," as if saying "_Oh_, what a glorious day
this is!"
This was the picture part of it--the glorious moving-picture show. Now
listen to some of the music:
"The sounds of the storm corresponded gloriously with the wild
exuberance of light and motion. The profound bass of the naked
branches and boles booming like waterfalls, the quick, tense
vibrations of the pine-needles, now rising to a shrill, whistling
hiss, now falling to a silky murmur. The rustling of laurel groves
in the dells, and the keen metallic click of leaf on leaf--all this
was heard in easy analysis when the attention was calmly bent.
"Even when the grand anthem had swelled to its highest pitch I
could distinctly hear the varying tones of individual
trees--spruce, fir, pine, and oak--and even the infinitely gentle
rustle of the withered grasses at my feet."
When the winds began to fall and the sky to clear, Muir climbed down and
made his way back home.
"The storm tones died away, and turning toward the east I beheld
the countless hosts of the forests hushed and tranquil, towering
above one another on the slopes of the hills like a devout
audience. The setting sun filled them with amber light, and seemed
to say while they listened:
"'My peace I give unto you.'"
HIDE AND SEEK IN THE LIBRARY
Did you know that the ash and maple seeds actually have screw
propellers, like a ship, so that they can ride on the wind?
Pettigrew's great work, "Design in Nature," makes this very plain,
both in word and picture.
In what way does the wind help to _produce_ the seed of grasses as
well as carry and plant them? (Any encyclopaedia or botany will tell
you how plants are fertilized.)
How could a tempest that blew down a tree help its seeds to get a
start? Wallace, in his "World of Life," says that on a full-grown
oak or beech there may be 100,000 seeds that are thus given a
better chance of life.
Speaking of "wind ploughs," what is the object of ploughing anyway?
The article on preparing the seed bed in "The Country Life Reader"
tells about what ploughing means to the soil and also:
Why good soil takes up more room than poor.
Why it is a good thing to plough deep, but a bad thing, if you
don't do it just right.
And farther on there is a most inspiring poem about the history of
the plough from the days of early Egypt to the present. It begins
like this:
"From Egypt behind my oxen,
With their stately step and slow,
Northward and east and west I went,
To the desert and the snow;
Down through the centuries, one by one,
Turning the clod to the shower,
Till there's never a land beneath the sun
But has blossomed behind my power."
The deserts have helped to make western China fertile. How did they
do it? (Look at your geography map and remember that the prevailing
winds of the world are westerly.)
You'll find many interesting things about the winds and the soil in
Keffer's "Nature Studies on the Farm" and Shaler's "Outlines of
Earth's History." Shaler's "Man and the Earth" says a single gale
may blow away more soil from an unprotected field than could be
made in a geological age, and an hour's rain may carry off more
than would pass away in a thousand years if the land were in its
natural state. He also tells what to do to prevent the best part of
ploughed fields from being carried off by the wind.
Have you any idea how far seed may be carried by a hurricane?
Wallace, in his "Darwinism" deals with this question, and it's very
important in the story of the earth. Beal's admirably written and
illustrated little book on "Seed Dispersal" tells a world of
interesting things about the wind as a sower. For instance:
How pigweed seeds are built so that wind can help them toboggan on
snow or float on water;
How wind and water work together in the distribution of seeds;
About seeds that ride in an ice-boat;
About the monoplane of the basswood;
About the "flail" of the buttonwood, and how the wind helps it to
whip out the seeds; and how the seeds then open their parachutes.
Dandelions go through quite a remarkable process in preparing for
flight. I wonder if you have ever noticed it. Before the seeds get
ripe Mother Dandelion blankets them at night and puts a rain-cloak
on them on rainy days, and just won't let them get out, as shown on
page 51. And do you know how she opens the flowers for the bees on
sunshiny days?
There is no island, no matter how remote, that isn't supplied with
insects. How do you suppose they get there? You may be sure the
wind has something to do with it or I wouldn't mention the subject
at the end of this chapter. (Wallace: "Darwinism.")
[Illustration: THE WEST WINDS AND THE RAINS
On the western slopes of this mountain the trees, with the help of the
winds and the rain, climb to the very summit, while the other side of
the mountain remains only a barren rock. The moisture-laden winds from
the west glide up the slope, the air expands as it rises, the expansion
cools it and down comes the rain! But the eastern slope gets little or
none of it.]