However, the perceptible decline in our larder, and the uncertainty of the time to be occupied in further explorations, forbid more than these two days' stay at the falls and cañon. The sun this morning shone brightly, and its rays were reflected upon the sides of the dismal cañon—so dark, and gray, and still—enlivening and brightening it. To-day has been warm, and nature this morning seemed determined that our last look should be the brightest, for the beauties of the entire landscape invited us to make a longer stay, and we lingered till the last moment, that the final impression might not be lost.
Pursuing our journey, at two miles above the falls we crossed a small stream which we named "Alum" creek, as it is strongly impregnated with alum.
Six miles above the upper fall we entered upon a region remarkable for the number and variety of its hot springs and craters. The principal spring, and the one that first meets the eye as you approach from the north, is a hot sulphur spring, of oval shape, the water of which is constantly boiling and is thrown up to the height of from three to seven feet. Its two diameters are about twelve feet and twenty feet, and it has an indented border of seemingly pure sulphur, about two feet wide and extending down into the spring or cauldron to the edge of the water, which at the time of our visit, if it had been at rest, would have been fifteen or eighteen inches below the rim of the spring. This spring is situated at the base of a low mountain, and the gentle slope below and around the spring for the distance of two hundred or three hundred feet is covered to the depth of from three to ten inches with the sulphurous deposit from the overflow of the spring. The moistened bed of a dried-up rivulet, leading from the edge of the spring down inside through this deposit, showed us that the spring had but recently been overflowing. Farther along the base of this mountain is a sulphurous cavern about twenty feet deep, and seven or eight feet in diameter at its mouth, out of which the steam is thrown in jets with a sound resembling the puffing of a steam-boat when laboring over a sand-bar, and with as much uniformity and intonation as if emitted by a high-pressure engine. From hundreds of fissures in the adjoining mountain from base to summit, issue hot sulphur vapors, the apertures through which they escape being encased in thick incrustations of sulphur, which in many instances is perfectly pure. There are nearby a number of small sulphur springs, not especially remarkable in appearance.
About one hundred yards from these springs is a large hot spring of irregular shape, but averaging forty feet long by twenty-five wide, the water of which is of a dark muddy color. Still farther on are twenty or thirty springs of boiling mud of different degrees of consistency and color, and of sizes varying from two to eight feet in diameter, and of depths below the surface varying from three to eight feet. The mud in these springs is in most cases a little thinner than mortar prepared for plastering, and, as it is thrown up from one to two feet, I can liken its appearance to nothing so much as Indian meal hasty pudding when the process of boiling is nearly completed, except that the puffing, bloated bubbles are greatly magnified, being from a few inches to two feet in diameter. In some of the springs the mud is of dark brown color, in others nearly pink, and in one it was almost yellow. Springs four or five feet in diameter and not over six feet apart, have no connection one with another either above or beneath the surface, the mud in them being of different colors. In some instances there is a difference of three feet in the height to which the mud in adjoining springs attains. There may be in some instances two or more springs which receive their supply of mud and their underground pressure from the same general source, but these instances are rare, nor can we determine positively that such is the case. This mud having been worked over and over for many years is as soft as the finest pigments.
All of these springs are embraced within a circle the radius of which is from a thousand to twelve hundred feet, and the whole of this surface seems to be a smothered crater covered over with an incrustation of sufficient strength and thickness to bear usually a very heavy weight, but which in several instances yielded and even broke through under the weight of our horses as we rode over it. We quickly dismounted, and as we were making some examinations, the crust broke through several times in some thin places through which vapor was issuing. Under the whole of this incrustation the hottest fires seem to be raging, and the heat issuing from the vents or from the crevices caused from the breaking in of the surface is too intense to be borne by the gloved hand for an instant. Surrounding the natural vents are deposits of pure sulphur, portions of which in many instances we broke off, and after allowing them to cool, brought them away with us. On the top of the mountain overlooking the large sulphur spring is a small living crater about six inches in diameter, out of which issue hot vapor and smoke. On the slope adjoining the mud spring is another crater of irregular shape, but embracing about one hundred square inches, out of which issues hot vapor, the rocks adjoining changing color under the intense heat with every breath blown upon them.
The tramp of our horses' feet as we rode over the incrustation at the base of the mountain returned a hollow sound; yet while some of our party were not disposed to venture upon it with their horses, still I think with care in selecting a route there is very little danger in riding over it.
On the mountain, large quantities of sulphur formed by the condensation of the vapor issuing from the crevices, now closed, but once in activity in the incrusted covering, have been deposited, and we collected many specimens of pure and crystallized sulphur. Thousands of pounds of pure and nearly pure sulphur are now lying on the top and sides of the mountain, all of which can be easily gathered with the aid of a spade to detach it from the mountain side incrustations to which it adheres in the process of condensation. We gave to this mountain the name "Crater hill."
Five miles further on we camped near the "Mud geyser." Our course to-day has been for the greater part over a level valley, which was plainly visible from the top of Mount Washburn. The water of the river at this point is strongly impregnated with the mineral bases of the springs surrounding our camp, and that empty into the river above it.