MOUNDS OF MINERAL DEPOSITS

I have the extremely difficult task of representing emotions by

words--glories of color and form seen by the eye by symbols meant to be

addressed to the ear. Before seeking to describe the diverse colors

made largely by one substance, let us remember that while silica, the

principal part of these water-built mounds, is one of the three parts

of granite, namely, the white crystal quartz, it is also the substance

of the beautifully variegated jasper, the lapis lazuli, the green

malachite, and the opal, with its cloudy milk-whiteness through which

flashes its heart of fire. Silica and alumina combine to make common

clay, but alumina forms itself into the red ruby, the golden-tinted

topaz, the violet oriental amethyst, the red, white, yellow, and violet

sapphire, and the beautiful green emerald. With substances of such

rare capabilities we may expect rich results in color and form.

We turn now to deposits from water of these two substances, especially

the first. About the Old Faithful geyser is a mound about one hundred

and forty-five feet broad at the base, twelve feet high, jeweled over

with pools of beauty of every shape, beaded and fretted with glories of

color never seen before except in the sky. How were they made?

Water is a general solvent. It can take into its substance several

similar bulks of other substances without greatly increasing its own,

some actually diminishing it. Hot alkaline water will dissolve even

silica rock. When water is saturated with sugar, salt, or other

substance, if a little or much water is evaporated some of the

saturating substance must be deposited as a solid. All crystals, as

quartz or diamonds, have been made by deposits from water. Hot water

can hold in solution much more of a solid than cold water. Therefore,

when hot water comes out of the earth and is cooled, some of the

saturating substance must be deposited as a solid. It is done in

various ways, especially two.

Suppose a little pool with perpendicular sides, say twenty feet across.

It leaps and boils two feet high. It deposits nothing till the water

comes to the cooling edge. Then it builds up a wall where it

overflows, and wherever it flows it builds. The result is that you

walk up the gentle slopes of a broad flat cone, and find the little

lakelet in a gorgeous setting, perfectly full at every point of the

circumference. If there is but little overflow, the result may be to

deposit all the matter where it first cools, and make a perpendicular

wall around the cup two or ten feet high. If the overflow is too much

to be cooled at once, the deposit may still be made fifty or one

hundred feet from the point of issue. If the overflow is sufficient,

it may be building up every inch of a vast cone at once, every foot

being wet.

[Illustration: The Punch Bowl, Yellowstone Geysers.]

Many minerals are held in solution and are deposited at various stages

of evaporation. Let us suppose the lake to have the bottom sloping

toward the abysmal center; the different minerals will be assorted as

if with a sieve. At the Sunlight Basin the edge is as flaming red as

one ever sees in the sunlit sky. And every color ever seen in a sunset

flames almost as brilliantly in the varying depths. Suppose a low cone

to be flooded only occasionally, as in the case of the Old Faithful

geyser. The cooled water falling from the upper air builds up, under

the terrible drench of the cataract, walls three or four inches high,

making pools of every conceivable shape, a few inches deep, in which

are the most exquisite and varied colors ever seen by mortal eye. You

walk about on these dividing walls and gaze into the beaded and

impearled pools of a hundred shades of different colors, never equaled

except by that perpetual glory of the sunset.

Consider the case of a pool that does not overflow. Just as lakes that

have no outlet must grow more and more salt till some have become solid

salt beds, so must this pool, tossing its hot waves two or three feet

high, evaporate its water and deposit its solids. Where? First,

against the cooler sides of the rock under the water, tending to reduce

the opening to a mere throat. Second, each wavelet tossed in air is

cooled, and deposits on the edge, solid as quartz, a crust that

overhangs the pool and tends to close it over as with hot ice. It may

build thus a mound fifteen feet high with an open throat in the middle.

Thus the pool has constructed an intermittent geyser. If the water

supply continues, it also destroys itself. The throat closes up by its

own deposits. It is a case of geyseral membranous croup.

I exceedingly longed to try vivisection on a geyser, or at least take

one of half a hundred, drain it off, and make a post-mortem

examination. On my very last day I found opportunity. I found a dead

geyser, though not by any means yet cold. It was still so hot that

people had given it an infernal name. I squeezed myself down through

its hot throat, which seemed a veritable open sepulcher, and found a

cave about twenty-five feet deep, twelve feet wide, and about sixty

feet long. It was elliptical in form, the sides coming together at a

sharp angle at the ends, bottom, and top. The way down to the fiery

heart of the earth had simply grown up by deposits of silex on the

sides and at the bottom. The water had evaporated by the intense heat,

and I was in the hot hollow that had once held an earthquake and

volcano. When I squeezed up to the blessed upper air I was glad there

was no help from below.

I could tell of mounds that grew so fast as to inclose the limbs of a

tree, making the firmest kind of a ladder by which I climbed to the

top; of floods that overflowed acres of forest, leaving every tree

firmly planted in solid rock; of mounds hundreds of feet high, covering

twenty acres with forms of indescribable beauty--but I despair. The

half has not been told. It cannot be. Great and marvelous are all Thy

works, Lord God Almighty! In wisdom hast Thou made them all.

Emerson says: "Whilst common sense looks at things or visible nature as

real and final facts, poetry, or the imagination which dictates it, is

a second sight, looking through these, and using them as types or words

for thoughts which they signify." Using these faculties and not mere

eyesight, one must surely say: "Since this world, in power, fineness,

finish, beauty, and adaptations not only surpasses our accomplishment,

but also is past our finding out to its perfection, it must have been

made by One stronger, finer, and wiser than we are."

Among the Forces · 第 39 / 43 题