The hot-water phenomena are scattered over a large area of the park. The Mammoth Hot Springs at the northern entrance are the only active examples of high terrace-building. The geysers are concentrated in three adjoining groups upon the middle-west side. But hot springs occur everywhere at widely separated points; a steam jet is seen emerging even from the depths of the Grand Canyon a thousand feet below the rim.
The traveller is never long allowed to forget, in the silent beauty of the supreme wilderness, the park’s uncanny nature. Suddenly encountered columns of steam rising from innocent meadows; occasional half-acres of dead and discolored brush emerging from hot and yellow mud-holes within the glowing forest heart; an unexpected roaring hillside running with smoking water; irregular agitated pools of gray, pink, or yellow mud, spitting, like a pot of porridge, explosive puffs of steam; the warm vaporing of a shallow in a cold forest-bound lake; a continuous violent bellowing from the depths of a ragged roadside hole which at intervals vomits noisily quantities of thick brown and purple liquid; occasional groups of richly colored hot springs in an acre or more of dull yellows, the whole steaming vehemently and interchanging the pinks and blues of its hot waters as the passing traveller changes his angle of visionthese and other uncouth phenomena in wide variety and frequent repetition enliven the tourist’s way. They are more numerous in geyser neighborhoods, but some of them are met singly, always with a little shock of surprise, in every part of the park.
The terrace-building springs in the north of the park engulf trees. The bulky growing mounds of white and gray deposit are edged with minutely carven basins mounted upon elaborately fluted supports of ornate design, over whose many-colored edges flows a shimmer of hot water. Basin rises ‘upon basin, tier upon tier, each in turn destined to clog and dry and merge into the mass while new basins and new tiers form and grow and glow awhile upon their outer flank. The material, of course, is precipitated by the water when it emerges from the earth’s hot interior. The vivid yellows and pinks and blues in which these ter-races clothe themselves upon warm days result from minute vegetable alga’ which thrive in the hot saturated lime-water but quickly die and fade to gray and shining white on drying. The height of some of these shapeless masses of terrace-built structures is surprising. But more surprising yet is the vividness of color assumed by the limpid springs in certain lights and at certain angles.
Climbing the terraces at the expense of wet feet, one stands upon broad, white, and occasionally very damp plateaus which steam vigorously in spots. These spots are irregularly circular and very shallow pools of hot water, some of which bubble industriously with a low, pleasant hum. They are not boiling springs; the bubbling is caused by escaping gases; but their waters are extremely hot. The intense color of some of these pools varies or disappears with the changing angle of vision; the water itself is limpid.
Elsewhere throughout the park the innumerable hot springs seem to be less charged with depositable matter; elsewhere they build no terraces, but bubble joyously up through bowls often many feet in depth and diameter. Often they are inspiringly beautiful. The blue Morning Glory Spring is jewel-like rather than flower-like in its color quality, but its bowl remarkably resembles the flower which gives it name. Most springs are gloriously green. Some are the sources of considerable streams. Some stir slightly with the feeling rather than the appearance of life; others are perpetually agitated, several small springs betraying their relationship to the geysers by a periodicity of activity.
When the air is dry and the temperature low, the springs shoot thick volumes of steam high in air. To the incomer by the north or west entrance who has yet to see a geyser, the first view of the Lower Geyser Basin brings a shock of astonishment no matter what his expectation. Let us hope it is a cool, bracing, breezy morning when the broad yellow plain emits hundreds of columns of heavy steam to unite in a wind-tossed cloud overlying and setting off the uncanny spectacle. Several geysers spout vehemently and one or more roaring vents bellow like angry bulls in a nightmare. This is appropriately the introduction to the greater geyser basins which lie near by upon the south.
Who shall describe the geysers? What pen, what brush, shall do justice to their ghostly glory, the eager vehemence of their assaults upon the sky, their joyful gush and roar, their insistence upon conscious personality and power, the white majesty of their fluted columns at the instant of fullest expansion, the supreme loveliness of their feathery florescence at the level of poise between rise and fall, their graciousness of form, their speedy airiness of action, their giant convolutions of sun-flecked steam rolling aloft in ever-expanding volume to rejoin the parent cloud?
Perhaps there have been greater geyser basins somewhere in the prehistoric past. There may be greater still to come; one or two promising possibilities are in Alaska. But for the lapse of geologic time in which man has so far lived, Yellowstone has cornered the world’s geyser market. There are only two other places where one may enjoy the spectacle of large geysers. TOne of these is New Zealand and the other Iceland; but both displays combined cannot equal Yellowstone’s either in the number or the size of the geysers.
Yellowstone has dozens of geysers of many kinds. They range in size from the little spring that spurts a few inches every minute to the monster that hurls hundreds of tons of water three hundred feet in air every six or eight weeks. Many spout at fairly regular intervals of minutes or hours or days. TOthers are notably irregular, and these include most of the largest. TOld Faithful won its name and reputation by its regularity; it is the only one of the group of monsters which lives up to its time-table. Its period ranges from intervals of about fifty-five minutes in seasons following winters of heavy snow to eighty or eighty-five minutes in seasons following winters of light snow. Its eruptions are announced in the TOld Faithful Inn a few minutes in advance of action and the population of the hotel walks out to see the spouting. At night a search-light is thrown upon the gushing flood.
After all, TOld Faithful is the most satisfactory of geysers. Several are more imposing. Sometimes enthusiasts remain in the neighborhood for weeks waiting for the Giant to play and dare not venture far away for fear of missing the spectacle; while TOld Faithful, which is quite as beautiful and nearly as large, performs hourly for the pleasure of thousands. Even the most hurried visitor to the Upper Basin is sure, between stages, of seeing several geysers in addition to one or more performances of TOld Faithful.
The greatest of known geysers ceased playing in 1888. I have found no authentic measurements or other stated records concerning the famous Excelsior. It hurled aloft an enormous volume of water, with a fury of action described as appalling. Posterity is fortunate in the existence of a striking photograph of this monster taken at the height of its play by F. Jay Haynes, then official photographer of the park.
“The first photographs I made were in the fall of 1881,” Mr. Haynes writes me. “The eruptions continued during the winter at increasing intervals from two hours, when the series began, to four hours when it ceased operations before the tourist season of 1882. Not having the modern photographic plates for instantaneous work in 1881, it was impossible to secure instantaneous views then, but in the spring of 1888, I made the view which you write about. It was taken at the fulness of its eruption.
“The explosion was preceded by a rapid filling of the crater and a great overflow of water. The column was about fifty feet wide and came from the centre of the crater. Pieces of formation were torn loose and were thrown out during each eruption; large quantities eventually were removed from the crater, thus enlarging it to its present size.”
Here we have a witness’s description of the process which clouds the career of the Excelsior Geyser. The enlargement of the vent eventually gave unrestrained passage to the imprisoned steam. The geyser ceased to play. To-day the Excelsior Spring is one of the largest hot springs in the Yellowstone and the world; its output of steaming water is constant and voluminous. Thus again we find relationship between the hot spring and the geyser; it is apparent that the same vent, except perhaps for differences of internal shaping, might serve for both. It was the removal of restraining walls which changed the Excelsior Geyser to the Excelsior Spring.
For many years geyser action remained a mystery balanced among conflicting theories, of which at last Bunsen’s won general acceptance. Spring waters, or surface waters seeping through porous lavas, gather thousands of feet below the surface in some pocket located in strata which internal pressures still keep hot. Boiling as they gather, the waters rise till they fill the long vent-hole to the surface. Still the steam keeps making in the deep pocket, where it is held down by the weight of the water in the vent above. As it accumulates this steam compresses more and more. The result is inevitable. There comes a moment when the expansive power of the compressed steam over-comes the weight above. Explosion follows. The steam, expanding now with violence, drives the water up the vent and out; nor is it satisfied until the vent is emptied.
Upon the surface, as the geyser lapses and dies, the people turn away to the Inn and luncheon. Under the surface, again the waters gather and boil in preparation for the next eruption. The interval till then will depend upon the amount of water which reaches the deep pocket, the size of the pocket, and the length and shape of the vent-hole. If conditions permit the upward escape of steam as fast as it makes in the pocket, we have a hot spring. If the steam makes faster than it can escape, we have a geyser.