The Geysers are boiling springs, situated seventy-two miles north-east of Reykjavik, on a gritty slope, at the foot of a trap-hill three hundred feet high; and on the upper border of a green-marshy plain, sloping down towards a small river which runs meandering through it in a southern direction. They are about a hundred in number, and all located in an area of about a quarter of a mile. Three of them are erupting—the Great Geyser, Strokr, and the Little Geyser. These, with Blesi, the most beautiful of the non-erupting springs, and situated a little way above the great Geyser, are the principal attractions to a traveller; although all the others, with everything pertaining to such phenomena, are intensely interesting.
Geyser means gusher or rager; Strokr is derived from the verb to agitate, and signifies a churn. Instead of an abstract summary, I shall endeavour as far as possible to give a detailed account of what we saw, and in the order of its occurrence. This will enable the reader, as it were, to accompany us, and gather the distinctive and varied features of this marvellous scene from the same points of view.
We stand at the side of the great Geyser, on the upper or north-west corner of a slope; a low trap-hill above us, the green valley of Haukadal below, and columns, jets, and clouds of white steam rising, curling and waving from the numerous springs on this upper arid slope on which we stand. The surface immediately around us—flinty and paved in thin scaly layers—is of a gritty reddish irony colour, with streamlets of hot steaming water trickling along from the overflow of the Geysers, on their way to join the river below. A long continuous strip of verdant turf runs up into this slaggy region, between the great Geyser and Strokr; and elsewhere various little round green islet-patches about a foot in diameter occur in it; blooming like oases, and covered with parnassia, sea-pink, wild-thyme and butter-cups, all thriving and seeming to enjoy the thermal heat. Here we found many bits of stick, turf, moss, and flowers, incrusted over with the silicious deposit of the water and converted into beautiful petrifactions.
The great Geyser basin is situated on the top of a cone shaped mound, which, on account of the uneven nature of the surrounding ground, seems, from every different point of view, to vary in height. As we approached, it appeared seven feet; moving downwards from the plain, it seemed more than twice as high; while, from the bottom of a deep gully running immediately behind and separating it in one direction from the hill, it seemed to attain an elevation of thirty feet.
The basin—perfectly smooth, of a whitish colour, saucer-shaped, slightly oval instead of round, seventy-two feet at its greatest breadth, seventy feet mean diameter, and about four feet deep—is full of water to the brim. In the bottom or centre of this gigantic saucer, through the clear hot fluid, is seen a round hole ten feet in diameter. This is the top of a stony funnel or pipe which goes down perpendicularly to a depth of eighty-three feet.
The Geyser-water,[[9]] like many hot springs in India and other parts of the world, holds in solution a large proportion of silica or flint. It is well known that this substance, when fused with potash or soda, under certain circumstances readily dissolves in boiling water; and, under various other conditions, it diffuses itself throughout the arcana of nature; finding its way to varnish the stalk of corn in our fields, or the bamboo in Indian jungles, both preserving them from damp and adding strength to their extreme lightness. Fused masses of silica have at times been found among the ashes of a haycock which has been accidentally burned; and the same substance, arrested and deposited in crystalline lumps, is at times met with, though rarely, in joints of cane, and when so found is by the natives called Tabasheer.
This flint-depositing property, resident in the water, has enabled the Geyser to raise its own pipe, basin and mound. The original basin or orifice, when the spring began, must have been at the bottom of the tube; the overflow, spreading, would then continue to go on and form thin laminated cakes of silicious deposit around it; eruptions would keep the hole open and smooth at the edge, ever adding layer to layer till it became a tube.
Thus through the lapse of time—probably about a thousand years—tube, basin and cone have, without doubt, been built up to their present elevation; and will continue to rise till the weight of the super-encumbent column of water becomes so great as to exceed the eruptive forces, or these latter from any other cause cease to operate, when the Geyser will probably remain tranquil for a time, and then slowly continue to deposit flint on the surface edges, till at length they meet and finally altogether seal up the cone.
This supposition is not altogether hypothetical, but is deduced from our having observed, both here and elsewhere, mounds, plainly of Geyserine formation, thus covered over, extinct and silent; little rocky elevations left like warts on the surface of the ground; and even the tracks or dry-beds of the meandering rivulets, which once carried away their overflow, still left, distinctly traceable, down the sintery slope.
Strokr is situated about four-hundred feet south from the great Geyser. It has not a regularly formed basin like the other, but is surrounded to a considerable distance by a slight elevation, of light flinty grit and laminae, with sundry depressions in it; all being deposited after the manner already described. In the centre, through brown coloured sinter, is a deep hole, like a well, six feet in diameter at the surface, contracting as it descends and attaining a depth of nearly fifty feet. On looking down, the water is seen, ten or twelve feet from the surface—boiling hard, plop-plopping, roaring, choking, and rumbling continually; in fact, as its name indicates, agitated and seething like a churn. The edge, however, must be approached with great caution, as eruptions occur without any warning; when jets of boiling water shoot up to the height of sixty feet, or, when choked with turf to provoke an eruption, to the height of 150 feet.