The desert

by John C. Van Dyke

Footnotes

[4] Colorado is said to be the Spanish translation of the Piman name buqui aquimuti, according to the late Dr. Elliot Coues; but the Spanish word was so obviously used to denote the red color of the stream, that any translation from the Indian would seem superfluous.

CHAPTER V
LIGHT, AIR, AND COLOR

Popular ideas of the desert.

These deserts, cut through from north to south by a silent river and from east to west by two noisy railways, seem remarkable for only a few commonplace things, according to the consensus of public opinion. All that one hears or reads about them is that they are very hot, that the sunlight is very glaring, and that there is a sand-storm, a thirst, and death waiting for every traveller who ventures over the first divide.

Sunlight on desert.

Glare and heat.

There is truth enough, to be sure, in the heat and glare part of it, and an exceptional truth in the other part of it. It is intensely hot on the desert at times, but the sun is not responsible for it precisely in the manner alleged. The heat that one feels is not direct sunlight so much as radiation from the receptive sands; and the glare is due not to preternatural brightness in the sunbeam, but to there being no reliefs for the eye in shadows, in dark colors, in heavy foliage. The vegetation of the desert is so slight that practically the whole surface of the sand acts as a reflector; and it is this, rather than the sun’s intensity, that causes the great body of light. The white roads in Southern France, for the surface they cover, are more glaring than any desert sands; and the sunlight upon snow in Minnesota or New England is more dazzling. In certain spots where there are salt or soda beds the combination of heat and light is bewildering enough for anyone; but such places are rare. White is something seldom seen on desert lands, and black is an unknown quantity in my observations. Even lava, which is popularly supposed to be as black as coal, has a reddish hue about it. Everything has some color—even the air. Indeed, we shall not comprehend the desert light without a momentary study of this desert air.

Pure sunlight.

Atmospheric envelope.

The circumambient medium which we call the atmosphere is to the earth only as so much ground-glass globe to a lamp—something that breaks, checks, and diffuses the light. We have never known, never shall know, direct sunlight—that is, sunlight in its purity undisturbed by atmospheric conditions. It is a blue shaft falling perfectly straight, not a diffused white or yellow light; and probably the life of the earth would not endure for an hour if submitted to its unchecked intensity. The white or yellow light, known to us as sunlight, is produced by the ground-glass globe of air, and it follows readily enough that its intensity is absolutely dependent upon the density of the atmosphere—the thickness of the globe. The cause for the thickening of the aërial envelope lies in the particles of dust, soot, smoke, salt, and vapor which are found floating in larger or smaller proportions in all atmospheres.

Vapor particles.

Clear air.

In rainy countries like England and Holland the vapor particles alone are sufficiently numerous to cause at times great obscurity of light, as in the case of fog; and the air is only comparatively clear even when the skies are all blue. The light is almost always whitish, and the horizons often milky white. The air is thick, for you cannot see a mountain fifteen miles away in any sharpness of detail. There is a mistiness about the rock masses and a vagueness about the outline. An opera-glass does not help your vision. The obscurity is not in the eyes but in the atmospheric veil through which you are striving to see. On the contrary, in the high plateau country of Wyoming, where the quantities of dust and vapor in the air are comparatively small, the distances that one can see are enormous. A mountain seventy miles away often appears sharp-cut against the sky, and at sunset the lights and shadows upon its sides look only ten miles distant.

Dust particles.

Hazes.

But desert air is not quite like the plateau air of Wyoming, though one can see through it for many leagues. It is not thickened by moisture particles, for its humidity is almost nothing; but the dust particles, carried upward by radiation and the winds, answer a similar purpose. They parry the sunshaft, break and color the light, increase the density of the envelope. Dust is always present in the desert air in some degree, and when it is at its maximum with the heat and winds of July, we see the air as a blue, yellow, or pink haze. This haze is not seen so well at noonday as at evening when the sun’s rays are streaming through canyons, or at dawn when it lies in the mountain shadows and reflects the blue sky. Nor does it muffle or obscure so much as the moisture-laden mists of Holland, but it thickens the air perceptibly and decreases in measure the intensity of the light.

Seeing the desert air.

Sea breezes on desert.

Yet despite the fact that desert air is dust-laden and must be thickened somewhat, there is something almost inexplicable about it. It seems so thin, so rarefied; and it is so scentless—I had almost said breathless—that it is like no air at all. You breathe it without feeling it, you look through it without being conscious of its presence. Yet here comes in the contradiction. Desert air is very easily recognized by the eyes alone. The traveller in California when he wakes in the morning and glances out of the car-window at the air in the mountain canyons, knows instantly on which side of the Tehachepi Range the train is moving. He knows he is crossing the Mojave. The lilac-blue veiling that hangs about those mountains is as recognizable as the sea air of the Massachusetts shore. And, strange enough, the sea breezes that blow across the deserts all down the Pacific coast have no appreciable effect upon this air. The peninsula of Lower California is practically surrounded by water, but through its entire length and down the shores of Sonora to Mazatlan, there is nothing but that clear, dry air.

Colored air.

Different hues.

I use the word “clear” because one can see so far through this atmosphere, and yet it is not clear or we should not see it so plainly. There is the contradiction again. Is it perhaps the coloring of it that makes it so apparent? Probably. Even the clearest atmosphere has some coloring about it. Usually it is an indefinable blue. Air-blue means the most delicate of all colors—something not of surface depth but of transparency, builded up by superimposed strata of air many miles perhaps in thickness. This air-blue is seen at its best in the gorges of the Alps, and in the mountain distances of Scotland; but it is not so apparent on the desert. The coloring of the atmosphere on the Colorado and the Mojave is oftener pink, yellow, lilac, rose-color, sometimes fire-red. And to understand that we must take up the ground-glass globe again.

Producing color.

Refracted rays.

It has been said that our atmosphere breaks, checks, and diffuses the falling sunlight like the globe of a lamp. It does something more. It acts as a prism and breaks the beam of sunlight into the colors of the spectrum. Some of these colors it deals with more harshly than others because of their shortness and their weakness. The blue rays, for instance, are the greatest in number; but they are the shortest in length, the weakest in travelling power of any of them. Because of their weakness, and because of their affinity (as regards size) with the small dust particles of the higher air region, great quantities of these rays are caught, refracted, and practically held in check in the upper strata of the atmosphere. We see them massed together overhead and call them the “blue sky.” After many millions of these blue rays have been eliminated from the sunlight the remaining rays come down to earth as a white or yellow or at times reddish light, dependent upon the density of the lower atmosphere.

Cold colors, how produced.

Warm colors.

Now it seems that an atmosphere laden with moisture particles obstructs the passage earthward of the blue rays, less perhaps than an atmosphere laden with dust. In consequence, when they are thus allowed to come down into the lower atmosphere in company with the other rays, their vast number serves to dominate the others, and to produce a cool tone of color over all. So it is that in moist countries like Scotland you will find the sky cold-blue and the air tinged gray, pale-blue, or at twilight in the mountain valleys, a chilly purple. A dust-laden atmosphere seems to act just the reverse of this. It obstructs all the rays in proportion to its density, but it stops the blue rays first, holds them in the upper air, while the stronger rays of red and yellow are only checked in the lower and thicker air-strata near the earth. The result of this is to produce a warm tone of color over all. So it is that in dry countries like Spain and Morocco or on the deserts of Africa and America, you will find the sky rose-hued or yellow, and the air lilac, pink, red, or yellow.

Sky colors.

I mean now that the air itself is colored. Of course countless quantities of light-beams and dispersed rays break through the aërial envelope and reach the earth, else we should not see color in the trees or grasses or flowers about us; but I am not now speaking of the color of objects on the earth, but of the color of the air. A thing too intangible for color you think? But what of the sky overhead? It is only tinted atmosphere. And what of the bright-hued horizon skies at sunrise and sunset, the rosy-yellow skies of Indian summer! They are only tinted atmospheres again. Banked up in great masses, and seen at long distances, the air-color becomes palpably apparent. Why then should it not be present in shorter distances, in mountain canyons, across mesas and lomas, and over the stretches of the desert plains?

Color produced by dust.

Effect of heat.

The truth is all air is colored, and that of the desert is deeper dyed and warmer hued than any other for the reasons just given. It takes on many tints at different times, dependent upon the thickening of the envelope by heat and dust-diffusing winds. I do not know if it is possible for fine dust to radiate with heat alone; but certain it is that, without the aid of the wind, there is more dust in the air on hot days than at any other time. When the thermometer rises above 100° F., the atmosphere is heavy with it, and the lower strata are dancing and trembling with phantoms of the mirage at every point of the compass. It would seem as though the rising heat took up with it countless small dust-particles and that these were responsible for the rosy or golden quality of the air-coloring.

Effect of winds.

Sand-storms.

There is a more positive tinting of the air produced sometimes by high winds. The lighter particles of sand are always being drifted here and there through the aërial regions, and even on still days the whirlwinds are eddying and circling, lifting long columns of dust skyward and then allowing the dust to settle back to earth through the atmosphere. The stronger the wind, and the more of dust and sand, the brighter the coloring. The climax is reached in the dramatic sand-storm—a veritable sand-fog which often turns half the heavens into a luminous red, and makes the sun look like a round ball of fire.

Reflections upon sky.

Blue, yellow, and pink hazes.

The dust-particle in itself is sufficient to account for the warmth of coloring in the desert air—sufficient in itself to produce the pink, yellow, and lilac hazes. And yet I am tempted to suggest some other causes. It is not easy to prove that a reflection may be thrown upward upon the air by the yellow face of the desert beneath it—a reflection similar to that produced by a fire upon a night sky—yet I believe there is something of the desert’s air-coloring derived from that source. Nor is it easy to prove that a reflection is cast by blue, pink, and yellow skies, upon the lower air-strata, yet certain effects shown in the mirage (the water illusion, for instance, which seems only the reflection of the sky from heated air) seem to suggest it. And if we put together other casual observations they will make argument toward the same goal. For instance, the common blue haze that we may see any day in the mountains, is always deepest in the early morning when the blue sky over it is deepest. At noon when the sky turns gray-blue the haze turns gray-blue also. The yellow haze of the desert is seen at its best when there is a yellow sunset, and the pink haze when there is a red sunset, indicating that at least the sky has some part in coloring by reflection the lower layers of desert air.

The dust-veil.

Summer coloring.

Whatever the cause, there can be no doubt about the effect. The desert air is practically colored air. Several times from high mountains I have seen it lying below me like an enormous tinted cloud or veil. A similar veiling of pink, lilac, or pale yellow is to be seen in the gorges of the Grand Canyon; it stretches across the Providence Mountains at noonday and is to be seen about the peaks and packed in the valleys at sunset; it is dense down in the Coahuila Basin; it is denser from range to range across the hollow of Death Valley; and it tinges the whole face of the Painted Desert in Arizona. In its milder manifestations it is always present, and during the summer months its appearance is often startling. By that I do not mean that one looks through it as through a highly colored glass. The impression should not be gained that this air is so rose-colored or saffron-hued that one has to rub his eyes and wonder if he is awake. The average unobservant traveller looks through it and thinks it not different from any other air. But it is different. In itself, and in its effect upon the landscape, it is perhaps responsible for the greater part of what everyone calls “the wonderful color” of the desert.

Local hues.

Greens of desert plants.

And this not to the obliteration of local hue in sands, rocks, and plants. Quite independent of atmospheres, the porphyry mountains are dull red, the grease wood is dull green, the vast stretches of sand are dull yellow. And these large bodies of local color have their influence in the total sum-up. Slight as is the vegetation upon the desert, it is surprising how it seems to bunch together and count as a color-mass. Almost all the growths are “evergreen.” The shrubs and the trees shed their leaves, to be sure, but they do it so slowly that the new ones are on before the old ones are off. The general appearance is always green, but not a bright hue, except after prolonged rains. Usually it is an olive, bordering upon yellow. One can hardly estimate what a relieving note this thin thatch of color is, or how monotonous the desert might be without it. It is welcome, for it belongs to the scene, and fits in the color-scheme of the landscape as perfectly as the dark-green pines in the mountain scenery of Norway.

Color of sands.

Sands in mirage.

The sands, again, form vast fields of local color, and, indeed, the beds of sand and gravel, the dunes, the ridges, and the mesas, make up the most widespread local hue on the desert. The sands are not “golden,” except under peculiar circumstances, such as when they are whirled high in the air by the winds, and then struck broadside by the sunlight. Lying quietly upon the earth they are usually a dull yellow. In the morning light they are often gray, at noon frequently a bleached yellow, and at sunset occasionally pink or saffron-hued. Wavering heat and mirage give them temporary coloring at times that is beautifully unreal. They then appear to undulate slightly like the smooth surface of a summer sea at sunset; and the colors shift and travel with the undulations. The appearance is not common; perfect calm, a flat plain, and intense heat being apparently the conditions necessary to its existence.

Color of mountain walls.

Weather staining.

The rocks of the upper peaks and those that make the upright walls of mountains, though small in body of color, are perhaps more varied in hue than either the sands or the vegetation, and that, too, without primary notes as in the Grand Canyon of the Yellowstone. The reds are always salmon-colored, terra-cotta, or Indian red; the greens are olive-hued, plum-colored, sage-green; the yellows are as pallid as the leaves of yellow roses. Fresh breaks in the wall of rock may show brighter colors that have not yet been weather-worn, or they may reveal the oxidation of various minerals. Often long strata and beds, and even whole mountain tops show blue and green with copper, or orange with iron, or purple with slates, or white with quartz. But the tones soon become subdued. A mountain wall may be dark red within, but it is weather-stained and lichen-covered without; long-reaching shafts of granite that loom upward from a peak may be yellow at heart but they are silver-gray on the surface. The colors have undergone years of “toning down” until they blend and run together like the faded tints of an Eastern rug.

Influence of the air.

Peak of Baboquivari.

But granted the quantity and the quality of local colors in the desert, and the fact still remains that the air is the medium that influences if it does not radically change them all. The local hue of a sierra may be gray, dark red, iron-hued, or lead-colored; but at a distance, seen through dust-laden air, it may appear topaz-yellow, sapphire-blue, bright lilac, rose-red—yes, fire-red. During the heated months of summer such colors are not exceptional. They appear almost every evening. I have seen at sunset, looking north from Sonora some twenty miles, the whole tower-like shaft of Baboquivari change from blue to topaz and from topaz to glowing red in the course of half an hour. I do not mean edgings or rims or spots of these colors upon the peak, but the whole upper half of the mountain completely changed by them. The red color gave the peak the appearance of hot iron, and when it finally died out the dark dull hue that came after was like that of a clouded garnet.

Buttes and spires.

Sun-shafts through canyons.

The high ranges along the western side of Arizona, and the buttes and tall spires in the Upper Basin region, all show these warm fire-colors under heat and sunset light, and often in the full of noon. The colored air in conjunction with light is always responsible for the hues. Even when you are close up to the mountains you can see the effect of the air in small ways. There are edgings of bright color to the hill-ridges and the peaks; and in the canyons, where perhaps a sunshaft streams across the shadow, you can see the gold or fire-color of the air most distinctly. Very beautiful are these golden sun-shafts shot through the canyons. And the red shafts are often startling. It would seem as though the canyons were packed thick with yellow or red haze. And so in reality they are.

Complementary hues in shadow.

There is one marked departure from the uniform warm colors of the desert that should be mentioned just here. It is the clear blue seen in the shadows of western-lying mountains at sunset. This colored shadow shows only when there is a yellow or orange hued sunset, and it is produced by the yellow of the sky casting its complementary hue (blue) in the shadow. At sea a ship crossing a yellow sunset will show a marvellous blue in her sails just as she crosses the line of the sun, and the desert mountains repeat the same complementary color with equal facility and greater variety. It is not of long duration. It changes as the sky changes, but maintains always the complementary hue.

Colored shadows.

Blue shadows upon salt-beds.

The presence of the complementary color in the shadow is exceptional, however. The shadows cast by such objects as the sahuaro and the palo verde are apparently quite colorless; and so, too, are the shadows of passing clouds. The colored shadow is produced by reflection from the sky, mixed with something of local color in the background, and also complementary color. It is usually blue or lilac-blue, on snow for example, when there is a blue sky overhead; and lilac when shown upon sand or a blue stone road. Perhaps it does not appear often on the Mojave-Colorado because the surfaces are too rough and broken with coarse gravel to make good reflectors of the sky. The fault is not in the light or in the sky, for upon the fine sands of the dunes, and upon beds of fine gypsum and salt, you can see your own shadow colored an absolute indigo; and often upon bowlders of white quartz the shadows of cholla and grease wood are cast in almost cobalt hues.

How light makes color.

Desert sunsets.

All color—local, reflected, translucent, complementary—is, of course, made possible by light and has no existence apart from it. Through the long desert day the sunbeams are weaving skeins of color across the sands, along the sides of the canyons, and about the tops of the mountains. They stain the ledges of copper with turquoise, they burn the buttes to a terra-cotta red, they paint the sands with rose and violet, and they key the air to the hue of the opal. The reek of color that splashes the western sky at sunset is but the climax of the sun’s endeavor. If there are clouds stretched across the west the ending is usually one of exceptional brilliancy. The reds are all scarlet, the yellows are like burnished brass, the oranges like shining gold.

But the sky and clouds of the desert are of such unique splendor that they call for a chapter of their own.

CHAPTER VI
DESERT SKY AND CLOUDS

Commonplace things of nature.

The blue sky.

How silently, even swiftly, the days glide by out in the desert, in the waste, in the wilderness! How “the morning and the evening make up the day” and the purple shadow slips in between with a midnight all stars! And how day by day the interest grows in the long overlooked commonplace things of nature! In a few weeks we are studying bushes, bowlders, stones, sand-drifts—things we never thought of looking at in any other country. And after a time we begin to make mental notes on the changes of light, air, clouds, and blue sky. At first we are perhaps bothered about the intensity of the sky, for we have always heard of the “deep blue” that overhangs the desert; and we expect to see it at any and all times. But we discover that it shows itself in its greatest depth only in the morning before sunrise. Then it is a dark blue, bordering upon purple; and for some time after the sun comes up it holds a deep blue tinge. At noon it has passed through a whole gamut of tones and is pale blue, yellowish, lilac-toned, or rosy; in the late afternoon it has changed again to pink or gold or orange; and after twilight and under the moon, warm purples stretch across the whole reach of the firmament from horizon to horizon.

Changes in the blue.

Dawns on the desert.

But the changes in the blue during the day have no constancy to a change. There is no fixed purpose about them. The caprices of light, heat, and dust control the appearances. Sometimes the sky at dawn is as pallid as a snow-drop with pearly grays just emerging from the blue; and again it may be flushed with saffron, rose, and pink. When there are clouds and great heat the effect is often very brilliant. The colors are intense in chrome-yellows, golds, carmines, magentas, malachite-greens—a body of gorgeous hues upheld by enormous side wings of paler tints that encircle the horizon to the north and south, and send waves of color far up the sky to the cool zenith. Such dawns are seldom seen in moist countries, nor are they usual on the desert, except during the hot summer months.

Blue as a color.

The prevailing note of the sky, the one oftenest seen, is, of course, blue—a color we may not perhaps linger over because it is so common. And yet how seldom it is appreciated! Our attention is called to it in art—in a hawthorn jar as large as a sugar-bowl, made in a certain period, in a certain Oriental school. The æsthetic world is perhaps set agog by this ceramic blue. But what are its depth and purity compared to the ethereal blue! Yet the color is beautiful in the jar and infinitely more beautiful in the sky—that is beautiful in itself and merely as color. It is not necessary that it should mean anything. Line and tint do not always require significance to be beautiful. There is no tale or text or testimony to be tortured out of the blue sky. It is a splendid body of color; no more.

Sky from mountain heights.

The night sky.

You cannot always see the wonderful quality of this sky-blue from the desert valley, because it is disturbed by reflections, by sand-storms, by lower air strata. The report it makes of itself when you begin to gain altitude on a mountain’s side is quite different. At four thousand feet the blue is certainly more positive, more intense, than at sea-level; at six thousand feet it begins to darken and deepen, and it seems to fit in the saddles and notches of the mountains like a block of lapis lazuli; at eight thousand feet it has darkened still more and has a violet hue about it. The night sky at this altitude is almost weird in its purples. A deep violet fits up close to the rim of the moon, and the orb itself looks like a silver wafer pasted upon the sky.

Blackness of space.

The darkening of the sky continues as the height increases. If one could rise to, say, fifty thousand feet, he would probably see the sun only as a shining point of light, and the firmament merely as a blue-black background. The diffusion of light must decrease with the growing thinness of the atmospheric envelope. At what point it would cease and the sky become perfectly black would be difficult to say, but certainly the limit would be reached when our atmosphere practically ceased to exist. Space from necessity must be black except where the straight beams of light stream from the sun and the stars.

Bright sky-colors.

Horizon skies.

The bright sky-colors, the spectacular effects, are not to be found high up in the blue of the dome. The air in the zenith is too thin, too free from dust, to take deep colorings of red and orange. Those colors belong near the earth, along the horizons where the aërial envelope is dense. The lower strata of atmosphere are in fact responsible for the gorgeous sunsets, the tinted hazes, the Indian-summer skies, the hot September glows. These all appear in their splendor when the sun is near the horizon-line and its beams are falling through the many miles of hot, dust-laden air that lie along the surface of the earth. The air at sunset after a day of intense heat-radiation is usually so thick that only the long and strong waves of color can pass through it. The blues are almost lost, the neutral tints are missing, the greens are seen but faintly. The waves of red and yellow are the only ones that travel through the thick air with force. And these are the colors that tell us the story of the desert sunset.

Spectrum colors.

Bands of yellow.

The orange sky.

Ordinarily the sky at evening over the desert, when seen without clouds, shows the colors of the spectrum beginning with red at the bottom and running through the yellows, greens, and blues up to the purple of the zenith. In cool weather, however, this spectrum arrangement seems swept out of existence by a broad band of yellow-green that stretches half way around the circle. It is a pale yellow fading into a pale green, which in turn melts into a pale blue. In hot weather this pallor is changed to something much richer and deeper. A band of orange takes its place. It is a flame-colored orange, and its hue is felt in reflection upon valley, plain, and mountain peak. This indeed is the orange light that converts the air in the mountain canyons into golden mist, and is measurably responsible for the yellow sun-shafts that, streaming through the pinnacles of the western mountains, reach far across the upper sky in ever-widening bands. This great orange belt is lacking in that variety and vividness of coloring that comes with clouds, but it is not wanting in a splendor of its own. It is the broadest, the simplest, and in many respects the sublimest sunset imaginable—a golden dream with the sky enthroned in glory and the earth at its feet reflecting its lustre.

Desert clouds.

Rainfall.

But the more brilliant sunsets are only seen when there are broken translucent clouds in the west. There are cloudy days even on the desert. After many nights of heat, long skeins of white stratus will gather along the horizons, and out of them will slowly be woven forms of the cumulus and the nimbus. And it will rain in short squalls of great violence on the lomas, mesas, and bordering mountains. But usually the cloud that drenches a mountain top eight thousand feet up will pass over an intervening valley, pouring down the same flood of rain, and yet not a drop of it reaching the ground. The air is always dry and the rain-drop that has to fall through eight thousand feet of it before reaching the earth, never gets there. It is evaporated and carried up to its parent cloud again. During the so-called “rainy season” you may frequently see clouds all about the horizon and overhead that are “raining”—letting down long tails and sheets of rain that are plainly visible; but they never touch the earth. The sheet lightens, breaks, and dissipates two thousand feet up. It rains, true enough, but there is no water, just as there are desert rivers, but they have no visible stream. That is the desert of it both above and below.

Effect of the nimbus.

With the rain come trooping almost all the cloud-forms known to the sky. And the thick ones like the nimbus carry with them a chilling, deadening effect. The rolls and sheets of rain-clouds that cover the heavens at times rob the desert of light, air, and color at one fell swoop. Its beauty vanishes as by magic. Instead of colored haze there is gray gloom settling along the hills and about the mesas. The sands lose their lustre and become dull and formless, the vegetation darkens to a dead gray, and the mountains turn slate-colored, mouldy, unwholesome looking. A mantle of drab envelops the scene, and the glory of the desert has departed.

Cumuli.

Heap clouds at sunset.

All the other cloud-forms, being more or less transparent, seem to aid rather than to obscure the splendor of the sky. The most common clouds of all are the cumuli. In hot summer afternoons they gather and heap up in huge masses with turrets and domes of light that reach at times forty thousand feet above the earth. At sunset they begin to show color before any of the other clouds. If seen against the sun their edges at first gleam silver-white and then change to gold; if along the horizon to the north or south, or lying back in the eastern sky, they show dazzling white like a snowy Alp. As the sun disappears below the line they begin to warm in color, turning yellow, pink, and rose. Finally they darken into lilac and purple, then sink and disappear entirely. The smaller forms of cumulus that appear in the west at evening are always splashes of sunset color, sometimes being shot through with yellow or scarlet. They ultimately appear floating against the night sky as spots of purple and gray.

Strati.

Above the cumuli and often flung across them like bands of gauze, are the strati—clouds of the middle air region. This veil or sheet-cloud might be called a twilight cloud, giving out as it does its greatest splendor after the sun has disappeared below the verge. It then takes all colors and with singular vividness. At times it will overspread the whole west as a sheet of brilliant magenta, but more frequently it blares with scarlet, carmine, crimson, flushing up and then fading out, shifting from one color to another; and finally dying out in a beautiful ashes of roses. When these clouds and all their variations have faded into lilac and deep purples, there are still bright spots of color in the upper sky where the cirri are receiving the last rays of the sun.

Cirri.

Ice-clouds.

The cirrus with its many feathery and fleecy forms is the thinnest, the highest, and the most brilliant in light of all the clouds. Perhaps its brilliancy is due to its being an ice-cloud. It seems odd that here in the desert with so much heat rising and tempering the upper air there should be clouds of ice but a few miles above it. The cirrus and also the higher forms of the cumulo-stratus are masses of hoar-frost, spicules of ice floating in the air, instead of tiny globules of vapor.

Clouds of fire.

The celestial tapestry.

There is nothing remarkable about the desert clouds—that is nothing very different from the clouds of other countries—except in light, color, and background. They appear incomparably more brilliant and fiery here than elsewhere on the globe. The colors, like everything else on the desert, are intense in their power, fierce in their glare. They vibrate, they scintillate, they penetrate and tinge everything with their hue. And then, as though heaping splendor upon splendor, what a wonderful background they are woven upon! Great bands of orange, green, and blue that all the melted and fused gems in the world could not match for translucent beauty. Taken as a whole, as a celestial tapestry, as a curtain of flame drawn between night and day, and what land or sky can rival it!

The desert moon.

Rings and rainbows.

After the clouds have all shifted into purples and the western sky has sunk into night, then up from the east the moon—the misshapen orange-hued desert moon. How large it looks! And how it warms the sky, and silvers the edges of the mountain peaks, and spreads its wide light across the sands! Up, up it rises, losing something of its orange and gaining something in symmetry. In a few hours it is high in the heavens and has a great aureole of color about it. Look at the ring for a moment and you will see all the spectrum colors arranged in order. Pale hues they are but they are all there. Rainbows by day and rainbows by night! Radiant circles of colored light—not one but many. Arches above arches—not two or three but five solar bows in the sky at one time! What strange tales come out of the wilderness! But how much stranger, how much more weird and extraordinary the things that actually happen in this desert land.

Moonlight.

Stars.

High in the zenith rides the desert moon. What a flood of light comes from it! What pale, phosphorescent light! Under it miles and miles of cactus and grease wood are half revealed, half hidden; and far away against the dark mountains the dunes of the desert shine white as snow-clad hills in December. The stars are forth, the constellations in their places, the planets large and luminous, yet none of them has much color or sparkle. The moon dims them somewhat, but even without the moon they have not the twinkle of the stars in higher, colder latitudes. The desert air seems to veil their lustre somewhat, and yet as points of light set in that purple dome of sky how beautiful they are!

The midnight sky.

Alone in the desert.

Lying down there in the sands of the desert, alone and at night, with a saddle for your pillow, and your eyes staring upward at the stars, how incomprehensible it all seems! The immensity and the mystery are appalling; and yet how these very features attract the thought and draw the curiosity of man. In the presence of the unattainable and the insurmountable we keep sending a hope, a doubt, a query, up through the realms of air to Saturn’s throne. What key have we wherewith to unlock that door? We cannot comprehend a tiny flame of our own invention called electricity, yet we grope at the meaning of the blazing splendor of Arcturus. Around us stretches the great sand-wrapped desert whose mystery no man knows, and not even the Sphinx could reveal; yet beyond it, above it, upward still upward, we seek the mysteries of Orion and the Pleiades.

The mysteries.

Space and immensity.

What is it that draws us to the boundless and the fathomless? Why should the lovely things of earth—the grasses, the trees, the lakes, the little hills—appear trivial and insignificant when we come face to face with the sea or the desert or the vastness of the midnight sky? Is it that the one is the tale of things known and the other merely a hint, a suggestion of the unknown? Or have immensity, space, magnitude a peculiar beauty of their own? Is it not true that bulk and breadth are primary and essential qualities of the sublime in landscape? And is it not the sublime that we feel in immensity and mystery? If so, perhaps we have a partial explanation of our love for sky and sea and desert waste. They are the great elements. We do not see, we hardly know if their boundaries are limited; we only feel their immensity, their mystery, and their beauty.

The silences.

And quite as impressive as the mysteries are the silences. Was there ever such a stillness as that which rests upon the desert at night! Was there ever such a hush as that which steals from star to star across the firmament! You perhaps think to break the spell by raising your voice in a cry; but you will not do so again. The sound goes but a little way and then seems to come back to your ear with a suggestion of insanity about it.

The cry of the human.

A cry in the night! Overhead the planets in their courses make no sound, the earth is still, the very animals are mute. Why then the cry of the human? How it jars the harmonies! How it breaks in discord upon the unities of earth and air and sky! Century after century that cry has gone up, mobbing high heaven; and always insanity in the cry, insanity in the crier. What folly to protest where none shall hear! There is no appeal from the law of nature. It was made for beast and bird and creeping thing. Will the human never learn that in the eye of the law he is not different from the things that creep?

CHAPTER VII
ILLUSIONS

Reality and appearance.

In our studies of landscape we are very frequently made the victims of either illusion or delusion. The eye or the mind deceives us, and sometimes the two may join forces to our complete confusion. We are not willing to admit different reports of an appearance. The Anglo-Saxon in us insists that there can be only one truth, and everything else must be error. It is known, for instance, that Castle Dome, which looks down on the Colorado River from Western Arizona, is a turret of granite—gray, red, brown, rock-colored, whatever color you please. With that antecedent knowledge in mind how difficult it is for us to believe the report of our eyes which says that at sunset the dome is amethystine, golden, crimson, or perhaps lively purple. The reality is one thing, the appearance quite another thing; but why are not both of them truthful?

Preconceived impressions.

And how very shy people are about accepting a pink air, a blue shadow, or a field of yellow grass—sunlit lemon-yellow grass! They have been brought up from youth to believe that air is colorless, that shadows are brown or gray or sooty black, and that grass is green—bottle-green. The preconceived impression of the mind refuses to make room for the actual impression of the eyes, and in consequence we are misled and deluded.

Deception by sunlight.

But do the eyes themselves always report the truth? Yes; the truth of appearances, but as regards the reality they may deceive you quite as completely as the mind deceives you about the apparent. And for the deception of the eyes there is no wizard’s cell or magician’s cabinet so admirably fitted for jugglery as this bare desert under sunlight. Its combination of light and air seem like reflecting mirrors that forever throw the misshapen image in unexpected places, in unexpected lights and colors.

Distorted forms and colors.

Changed appearance of mountains.

What, for instance, could be more perplexing than the odd distortions in the forms and colors of the desert mountains! A range of these mountains may often look abnormally grand, even majestic in the early morning as they stand against the eastern sky. The outlines of the ridges and peaks may be clear cut, the light and shade of the canyons and barrancas well marked, the cool morning colors of the face-walls and foot-hills distinctly placed and holding their proper value in the scene. But by noon the whole range has apparently lost its lines and shrunken in size. Under the beating rays of the sun and surrounded by wavering heated atmosphere its shadow masses have been grayed down, neutralized, perhaps totally obliterated; and the long mountain surface appears as flat as a garden wall, as smooth as a row of sand-dunes. There is no indication of barranca or canyon. The air has a blue-steel glow that muffles light and completely wrecks color. Seen through it the escarpments show only dull blue and gray. All the reds, yellows, and pinks of the rocks are gone; the surfaces wear a burnt-out aspect as though fire had eaten into them and left behind only a comb of volcanic ash.

Changes in line, light, and color.

At evening, however, the range seems to return to its majesty and magnitude. The peaks reach up, the bases broaden, the walls break into gashes, the ridges harden into profiles. The sun is westering, and the light falling more obliquely seems to bring out the shadows in the canyons and barrancas. Last of all the colors come slowly back to their normal condition, as the flush of life to one recovering from a trance. One by one they begin to glow on chasm, wall, and needled summit. The air, too, changes from steel-blue to yellow, from yellow to pink, from pink to lilac, until at last with the sun on the rim of the earth, the mountains, the air, the clouds, and the sky are all glowing with the tints of ruby, topaz, rose-diamond—hues of splendor, of grandeur, of glory.

Suppose, if you please, a similar range of mountains thirty miles away on the desert. Even at long distance it shows an imposing bulk against the sky, and you think if you were close to it, wall and peak would loom colossal. How surprised you are then as you ride toward it, hour after hour, to find that it does not seem to grow in size. When you reach the foot-hills the high mountains seem little larger than when seen at a distance. You are further surprised that what appeared like a flat-faced range with its bases touching an imaginary curb-stone for miles, is in reality a group-range with retiring mountains on either side that lead off on acute angles. The group is round, and has as much breadth as length. And still greater is your surprise when you discover that the green top of the gray-based mountain, which has been puzzling you for so many hours, does not belong to the gray base at all. It is a pine-clad top resting upon another and more massive base far back in the group. It is the highest and most central peak of the range.

False perspective.

Abnormal foreshortening.

Contradictions and denials.

Such illusions are common, easily explained; and yet, after all, not so easily understood. They are caused by false perspective, which in turn is caused by light and air. On the desert, perspective is always erratic. Bodies fail to detach themselves one from another, foreshortening is abnormal, the planes of landscape are flattened out of shape or telescoped, objects are huddled together or superimposed one upon another. The disturbance in aërial perspective is just as bad. Colors, lights, and shadows fall into contradictions and denials, they shirk and bear false witness, and confuse the judgment of the most experienced.

Deceptive distances.

No wonder amid this distortion of the natural, this wreck of perspective, that distance is such a proverbially unknown quantity. It is the one thing the desert dweller speaks about with caution. It may be thirty or fifty miles to that picacho—he is afraid to hazard a guess. If you should go up to the top of your mountain range and look at the valley beyond it, the distance across might seem very slight. You can easily see to where another mountain range begins and trails away into the distance. Perhaps you fancy a few hours’ ride will take you over that valley-plain to where the distant foot-hills are lying soft and warm at the bases of the mountains. You may be right and then again you may be wrong. You may spend two days getting to those foot-hills.

Dangers of the desert.

Immensity of valley-plains.

This deception of distance is not infrequently accompanied by fatal consequences. The inexperienced traveller thinks the distance short, he can easily get over the ground in a few hours. But how the long leagues drag out, spin out, reach out! The day is gone and he is not there, the slight supply of water is gone and he is not there, his horse is gone and he himself is going, but he is not there. The story and its ending are familiar to those who live near the desert, for every year some mining or exploring party is lost. If there are any survivors they usually make the one report: “The distance seemed so short.” But there are no short distances on the desert. Every valley-plain is an immense wilderness of space.

Shadow illusions.

Color-patches on mountains.

There is another illusion—a harmless one—that has not to do with perspective but with shadow and local color. The appearance is that of shadows cast down along the mountain’s side by the ridges or hogbacks. Any little patch of shadow is welcome on the desert, particularly upon the mountains which are always so strongly flooded with light. But this is only a counterfeit presentment. The ridges have no vegetation upon them to hold in place the soil and rocks and these are continually breaking away into land-slips. The slips or slides expose to view streaks of local color such as may be seen in veins of iron and copper, in beds of lignite or layers of slate. It is these streaks and patches of dark color that have broken away and slipped down the mountain side under the ridges that give the appearance of shadows. They have the true value in light, and are fair to look upon even though they are deception. The weather-beaten rocks of a talus under a peak may create a similar illusion, but the shadow effect loses a velvety quality which it has when seen under the ridges.

Illusion of lava-beds.

Appearance of cloud-shadow.

The illusion of a cloud-shadow resting upon the foot-hills or in the valley, is frequently produced by the local color of lava-beds. Lava may be of almost any color, but when seen close to view it is usually a reddish-black. At a distance, however, and as a mass, its beds have the exact value of a cloud-shadow. Any eye would be deceived by it. The great inundations of lava that have overrun the plains and oozed down the foot-hills and around the lomas (particularly on the Mojave) look the shadow to the very life. The beds are usually hedged about on all sides by banks of fine sand that seem to stand for sunlight surrounding the shadow, and thus the deception is materially augmented. Many times I have looked up at the sky to be sure there was no cloud there, so palpable is this lava shadow-illusion.

Mirage.

Definition.

But perhaps the most beautiful deception known to the desert is the one oftenest seen—mirage. Everyone is more or less familiar with it, for it appears in some form wherever the air is heated, thickened, or has strata of different densities. It shows on the water, on the grass plains, over ploughed fields or gravel roads, on roadbeds of railways; but the bare desert with its strong heat-radiation is primarily its home. The cause of its appearance—or at least one of its appearances—is familiar knowledge, but it may be well to state it in dictionary terms: “An optical illusion due to excessive bending of light-rays in traversing adjacent layers of air of widely different densities, whereby distorted, displaced, or inverted images are produced.”[5]

Need of explanation.

This is no doubt the true explanation of that form of mirage in which people on Sahara see caravans in the sky trailing along, upside down, like flies upon the ceiling; or on the ocean see ships hanging in the air, masts and sails downward. But the explanation is very general and is itself in some need of explanation. Perhaps then I may be pardoned for trying to illustrate the theory of mirage in my own way.

Refraction of light-rays.

Dense air-strata.

The rays of light that come from the sun to the earth appear to travel in a straight line, but they never do. As soon as they meet with and pass into the atmospheric envelope they are bent or deflected from their original direction and reach the earth by obtuse angles or in long descending curves like a spent rifle ball. This bending of the rays is called refraction, which must not be confounded with reflection—a something quite different. Now refraction is, of course, the greatest where the atmosphere is the densest. The thicker the air the more acute the bending of the light-ray. Hence the thick layers of air lying along or a few feet above the surface of the earth on a hot day are peculiarly well-fitted to distort the light-ray, and consequently well-fitted to produce the effect of mirage. These layers of air are of varying densities. Some are thicker than others; and in this respect the atmosphere bears a resemblance to an ordinary photographic or telescopic lens. Let us use the lens illustration for a moment and perhaps it will aid comprehension of the subject.

Illustration of camera lens.

You know that the lens, like the air, is of varying thicknesses or densities, and you know that in the ordinary camera the rays of light, passing through the upper part of the lens, are refracted or bent toward the perpendicular so that they reach the ground-glass “finder” at the bottom; and that the rays passing through the lower part of the lens go to the top of the “finder” The result is that you have on the “finder” or the negative something reversed—things upside down. That, so far as the reversed image goes, is precisely the case in mirage. The air-layers act as a lens and bend the light-rays so that when seen in our “finder”—the eye—the bottom of a tree, for example, goes to the top and the top goes to the bottom.

The bent light-ray.

But there is something more to mirage than this reversed image. The eyes do not see things “in their place,” but see them hanging in the air as in the case of ships and caravans. To explain this, in the absence of a diagram, we shall have to take up another illustration. Suppose a light-ray so violently bent by the heat lying above a sidewalk that it should come to us around a street corner, and thereby we should see a man coming up a side street that lies at right angles to us. He would appear to our eyes to be coming up, not the side street, but the street we are standing in. The man, to all appearances, would not be “in his place.” We should see him where he is not.

Ships at sea.

Ships upside down.

Now suppose again instead of the light-rays bending to right or left (as in the street-corner illustration), we consider them as bending skyward or earthward. Suppose yourself at sea and that you are looking up into the sky above the horizon. You see there a ship “out of its place,” hanging in the air in an impossible manner—something which is equivalent, or at least analogous, to looking down the street and seeing the image of the man around the corner. You are looking straight into the sky, yet seeing a ship below the verge. The light-rays coming from the ship on the water describe an obtuse angle or curve in reaching the eye. The rays from the bottom of the ship, lying in a dense part of the air-lens, are more acutely bent than those from the masts, and hence they go to the top of the photographic plate or your field of vision, whereas the rays from the ship’s masts, being in a thinner atmosphere, are less violently bent, and thus go to the bottom of your field of vision. The result is the ship high in air above the horizon-line and upside down.

Wherein the illusion.

“Looming” of vessels, islands, and cities.

The illusion or deception consists in this: We usually see things in flat trajectory, so to speak. Light comes to us in comparatively straight rays. The mind, therefore, has formulated a law that we see only by straight rays. In the case of mirage the light comes to us on curved, bent, or angular rays. The eyes recognize this, but the mind refuses to believe it and hence is deceived. We think we see the ship in the air by the straight ray, but in reality we see the ship on the water by the bent ray. It is thus that ships are often seen when far below the horizon-line, and that islands in the sea below the ocean’s rim, and so far away as a hundred miles, are seen looming in the air. “Looming” is the word that describes the excessive apparent elevation of the object in the sky and is more striking on sea than land. Captains of vessels often tell strange tales of how high in the air, ships and towns and coasts are seen. The report has even come back from Alaska of a city seen in the sky that is supposed to be the city of Bristol. In tropical countries and over warm ocean-currents there are often very acute bendings of the light-rays. Why may it not be so in colder lands with colder currents?

Reversed image of mountains.

Horses and cattle in mirage.

The form of mirage that gives us the reversed image is seen on the desert as well as on the sea; but not frequently—at least not in my experience. There is an illusion of mountains hanging peak downward from the sky, but one may wander on the deserts for months and never see it. The reality and the phantom both appear in the view—the phantom seeming to draw up and out of the original in a distorted, cloud-like shape. It is almost always misshapen, and as it rises high in air it seems to be detached from the original by currents of air drifted in between. More familiar sights are the appearances of trees, animals, houses, wagons, all hanging in the air in enlarged and elongated shapes and, of course, reversed. I have seen horses hitched to a wagon hanging high up in the air with the legs of the horses twenty feet long and the wagon as large as a cabin. The stilted antelope “forty feet high and upside down” is as seldom seen in the sky as upon the earth; but desert cattle in bunches of half a dozen will sometimes walk about on the aërial ceiling in a very astonishing way.

Illusion of rising buttes.

Yet these, too, are infrequent appearances. Nor is the illusion of buttes rising from the plain in front of you often seen. It happens only when there are buttes at one side or the other, and, I presume, this mirage is caused by the bending of the light-rays to the right or left. It presents certainly a very beautiful effect. The buttes rise up from the ground, first one and then another, until there is a range of them that holds the appearance of reality perhaps for hours, and then gradually fades out like a stereopticon picture—the bases going first and the tops gradually melting into the sky. When seen at sunset against a yellow sky the effect is magnificent. The buttes, even in illusion, take on a wonderful blue hue (the complementary color of yellow), and they seem to drift upon the sky as upon an open sea.

Other causes for mirage.

Water-mirage.

The lake appearance.

How produced.

The bending of the light-rays to either side instead of up or down, as following the perpendicular, may or may not be of frequent occurrence. I do not even know if the butte appearance is to be attributed to that. The opportunity to see it came to me but once, and I had not then the time to observe whether the buttes in the mirage had sides the reverse of the originals. Besides, it is certain that mirage is caused in other ways than by the bending of light-rays. The most common illusion of the desert is the water-mirage and that is caused by reflection, not refraction. Its usual appearance is that of a lake or sea of water with what looks at a distance to be small islands in it. There are those with somewhat more lively imagination than their fellows who can see cows drinking in the water, trees along the margin of the shore (palms usually), and occasionally a farm-house, a ship, or a whale. I have never seen any of these wonderful things, but the water and island part of the illusion is to be seen almost anywhere in the desert basins during hot weather. In the lower portions of the Colorado it sometimes spreads over thousands of acres, and appears not to move for hours at a stretch. At other times the wavering of the heat or the swaying of the air strata, or a change in the density of the air will give the appearance of waves or slight undulations on the water. In either case the illusion is quite perfect. Water lying in such a bed would reflect the exact color of the sky over it; and what the eyes really see in this desert picture is the reflection of the sky not from water but from strata of thick air.

Objects in the water.

This illusion of water is probably seen more perfectly in the great dry lake-beds of the desert where the ground is very flat and there is no vegetation, than elsewhere. In the old Coahuila Valley region of the Colorado the water comes up very close to you and the more you flatten the angle of reflection by flattening yourself upon the ground, the closer the water approaches. The objects in it which people imagine look like familiar things are certainly very near. And these objects—wild-fowl, bushes, tufts of swamp grass, islands, buttes—are frequently bewildering because some of them are right side up and some of them are not. Some are reversed in the air and some are quietly resting upon the ground.

Confused mirage.

The swimming wolf.

It happens at times that the whole picture is confused by the light-rays being both reflected and refracted, and in addition that the rays from certain objects come to us in a direct line. The ducks, reeds, and tufts of grass, for instance, are only clods of dirt or sand-banked bushes which are detached at the bottom by heavy drifts of air. We see their tops right side up by looking through the air-layer or some broken portion of it. But in the same scene there may be trees upside down, and mountains seen in reflection, drawn out to stupendous proportions. In the Salton Basin one hot day in September a startled coyote very obligingly ran through a most brilliant water-mirage lying directly before me. I could only see his head and part of his shoulders, for the rest of him was cut off by the air-layer; but the appearance was that of a wolf swimming rapidly across a lake of water. The illusion of the water was exact enough because it was produced by reflection, but there was no illusion about the upper part of the coyote. The rays of light from his head and shoulders came to me unrefracted and unreflected—came as light usually travels from object to eye.

Colors and shadows in mirage.

But refracted or reflected, every feature of the water-mirage is attractive. And sometimes its kaleidoscopic changes keep the fancy moving at a pretty pace. The appearance and disappearance of the objects and colors in the mirage are often quite wonderful. The reversed mountain peaks, with light and shade and color upon them, wave in and out of the imaginary lake, and are perhaps succeeded by undulations of horizon colors in grays and pinks, by sunset skies and scarlet clouds, or possibly by the white cap of a distant sierra that has been caught in the angle of reflection.

Trembling air.

But with all its natural look one is at loss to understand how it could ever be seriously accepted as a fact, save at the first blush. People dying for water and in delirium run toward it—at least the more than twice-told tales of travellers so report—but I never knew any healthy eye that did not grow suspicious of it after the first glance. It trembles and glows too much and soon reveals itself as something intangible, hardly of earth, little more than a shifting fantasy. You cannot see it clear-cut and well-defined, and the snap-shot of your camera does not catch it at all.

Beauty of mirage.

Yet its illusiveness adds to, rather than detracts from, its beauty. Rose-colored dreams are always delightful; and the mirage is only a dream. It has no more substantial fabric than the golden haze that lies in the canyons at sunset. It is only one of nature’s veilings which she puts on or off capriciously. But again its loveliness is not the less when its uncertain, fleeting character is revealed. It is one of the desert’s most charming features because of its strange light and its softly glowing opaline color. And there we have come back again to that beauty in landscape which lies not in the lines of mountain valley and plain, but in the almost formless masses of color and light.