Page:The American Cyclopædia (1879) Volume VII.djvu/801

 GEYSERS 785 level. It is described by Von Hochstetter as a crater-like excavation, with steep reddish sides, 30 to 40 ft. high, which are open toward the lake only. The basin of the spring is about 80 ft. long and 60 wide, and is filled to the brim with clear transparent water, which against the white incrusted sides appears of a beauti- ful blue color. Immense clouds of steam con- tinually rise from it, obstructing the view of the surface, and the noise of boiling is always audible. At the margin the temperature is 183 F., but in the centre, where the water is continually in a state of ebullition to the height of several feet, it probably reaches the boiling point. The deposit, like that of the Iceland springs, is silicious, and the incrustations made by the overflow have formed on the slope a system of terraces, from 2 to 6 ft. in height, as white and almost as regular as if cut from marble, on each of which are circular basins, resplendent with blue water. These terraces, which cover an area of about three acres, have the appearance of a cataract plunging over natural shelves, which as it falls is suddenly turned into stone. Each stage has a small raised margin, from which slender stalactites hang down on the next below. At ordinary times but very little water ripples' over these terraces, and only the principal discharge on the side forms a hot steaming fall ; but some- times, say the natives, the whole body of water is thrown up in an enormous column, empty- ing the pool. On the highest stage is an ex- tensive platform, with a number of basins, from 5 to 6 ft. deep, the water showing a temper- ature of from 90 to 110 F. In the middle of this platform rises, close to the brink of the .main basin, a rock island, about 12 ft. high, covered with mosses and ferns. From it a full view may be had of the interior of the boil- ing caldron, without danger. The rocks from which these springs derive their silica are rhyolites and rhyolithic tufas, which contain over 70 per cent, of it. An analysis of the so- lidified incrustation of the Tetarata, made by Mayer, gave the following result : silica, 84'78 ; water and organic substances, 12*86 ; sesqui- oxide of iron and alumina, 1'27; lime, mag- nesia, and alkalies, 1-09; total, 100. In the United States, volcanic boiling springs exist in numerous localities west of the Rocky moun- tains. In the Colorado desert, between lat. 33 and 34, and Ion. 115 and 116, are re- markable mud volcanoes and boiling springs. The desert at this point is below the level of the sea. The springs cover a space not more than a quarter of a mile square. This area is covered with soft mud, through which water and steam are constantly escaping, with a noise audible at a distance of ten miles. In some places the vapor rises steadily, with a sharp hissing sound; in others it bursts forth with a loud explosion, throwing water and mud to the height of 100 ft. Some of the boiling springs throw up a column of water 20 or 30 ft. ; some have cones formed around them, and some have basins 100 ft. in diameter, in which the blue paste-like mud is ever bubbling and hissing. Many are incrusted with carbonate of lime, others with deposits of sulphur. The steam which rises from them is strongly im- pregnated with sulphur. Similar springs exist in New Mexico and in some of the other terri- tories. The so-called geysers of California are in Sonoma county, in a lateral gorge of the valley of Napa, called the "Devil's Canon," near the Pluton river. The narrow ravine, which is always filled with vapor, is shut in by steep hills, the sides of which, marked with evidences of volcanic action, are smoking with heat and bare of vegetation. A multitude of springs gush out at the base of the rocks. Hot and cold springs, boiling springs, and quiet springs lie within a few feet of each other. They differ also in color, smell, and taste. Some are clear and transparent, others white, yellow, or red with ochre, and still others are of an inky blackness. Some are sulphurous and fetid in odor, and some are charged with alum and salt. The " Steampipe " is an orifice in the hill- side, about 8 in. in diameter, from which a volume of steam rises with a continuous roar to a height varying from 50 to 200 ft. In a cavity called the "Witches' Caldron" amass of black fetid mud is ever bubbling with heat, the vapor from it depositing black flowers of sulphur on the rocks around. The surface of the ground about the springs, which is too hot to walk upon with thin shoes, is covered with the mine- rals deposited by the waters, among which are sulphur, sulphate of magnesia, sulphate of aluminum, and various salts of iron. These springs, none of which are properly geysers, are about 1,700 ft. above the sea. The geysers at the head waters of the Yellowstone and Mis- souri rivers are probably the most wonderful on the globe, even those in Iceland and New Zea- land sinking into insignificance when compared with them. The country lying between lat. 43 and 47 N., and Ion. 110 and 114 W., compri- sing portions of the territories of Idaho, Wyo- ming, and Montana, is dotted with groups of hot springs, the remains of most remarkable vol- canic manifestations, which began probably in the tertiary period. Earthquake shocks are still common throughout this region, and at some seasons of the year are very severe. The most of these springs are not geysers, but simply boil- ing mineral springs and mud volcanoes. The geysers proper are in the N. W. corner of Wyo- ming territory, on the Fire-Hole river, the mid- dle fork of the Madison, which is one of the three principal sources of the Missouri. The basin in which they are situated was visited first by a party under Cook and Folsom in 1869. In 1870 Gen. Washburne, surveyor general of Montana, explored it with a party, among whom were Lieut. G. 0. Doane and N. P. Langford; and in 1871 it was surveyed by Dr. F. V. Hay- den, United States geologist, and by Col. J. W. Barlow and Capt. D. P. Heap, of the United States engineer corps. Dr. R. W. Raymond,