W. H. Weed. Formation of Travertine and Siliceous Sinter by the Vegetation of Hot Springs, 9th Ann. Rept. U. S. Geol. Surv., 1889, pp. 613-676, pls. 78-87.
M. Neumayr. Erdgeschichte, vol. 1, pp. 500-510.
Arnold Hague. Soaping Geysers, Trans. Am. Inst. Min. Eng., vol. 17, 1889, pp. 546-553.
John Tyndall. Heat as a Mode of Motion, New York, 1873, pp. 115-121 (artificial geyser).
CHAPTER XV
SUN AND WIND IN THE LANDS OF INFREQUENT RAINS
The law of the desert.—It is well to keep ever in mind that there is no universal law which dominates Nature’s processes in all the sections of her realm. Those changes which, because often observed, are most familiar, may not be of general application, for the reason that the areas habitually occupied by highly civilized races together comprise but a small portion of the earth’s surface. In the dank tropical jungle, upon the vast arid sand plains, and in the cold white spaces near the poles, Nature has instituted peculiar and widely different processes.
The fundamental condition of the desert is aridity, and this necessitates an exclusion from it of all save the exceptional rain cloud. Thus deserts are walled in by mountain ranges which serve as barriers to intercept the moisture-bringing clouds. They are in consequence saucer-shaped depressions, often with short mountain ranges rising out of the bottoms, and such rain as falls within the inclosure is largely upon the borders. Of this rainfall none flows out from the desert, for the water is largely returned to the atmosphere through evaporation.