530 KIRK BRYAN 



springs are found in many arid countries in places where water 

 emerges under pressure. Good examples occur in the Tularosa 

 Basin in New Mexico/ 



Pool springs have large, deep orifices filled with clear water. 

 The pool is surrounded and partly covered with a shelf of fine earth 

 supported by a network of vegetable fibers. The shelf is formed, 

 like mounds, by the growth of vegetation and the filling of the 

 ensuing tangle with wind-blown sand and dust. The two types 

 occur in adjacent springs of the Fish Springs region, Utah, as 

 described by Meinzer.^ (See also p. 535 and Fig. 3.) 



Many springs deposit around their mouths mineral matter that 

 is carried in solution by the water. Calcium carbonate and silica 

 are the most common minerals of spring deposits. Mounds, plat- 

 forms, and ridges of considerable size are thus formed. 



Mud volcanoes — low conical mounds having a crater at the 

 top through which the water rises — are built up when water 

 containing clay or fine sand rises to the surface under pressure. As 

 the water spreads out of the vent it loses velocity and therefore 

 deposits the matter it had carried in suspension. Such deposits 

 are made by the temporary springs formed along fissures in uncon- 

 solidated rocks during earthquakes.^ The emission of volcanic 

 steam and gas through beds of tuff produces the same topographic 

 form. "Salses,'.' "air volcanoes," and "macculutos" are names 

 applied to such springs in different parts of the world. In many of 

 these springs the gases appear to be due to chemical changes in the 

 earth, rather than to volcanism.'' 



SPRING WATER 



The waters which circulate in the ground may be roughly 

 divided into two types: (i) deep-seated waters, and (2) shallow 

 waters. The shallow waters are derived largely from precipitation 



' O. E. Meinzer, "Geology and Water Resources of Tularosa Basin, New Mexico, 

 U.S. Geol. Survey, Water-Supply Paper 343 (1915), p. 52. 



2 O. E. Meinzer, "Ground Water in Juab, Millard, and Iron Counties, Utah, 

 U.S. Geol. Survey, Water-Supply Paper 277 (191 1), pp. 44-45- 



3 C. E. Button, "The Charleston Earthquake of August 31, 1886," U.S. Geol. 

 Survey, Ninth Annual Report (1889), pp. 28-284, Plate XX. 



4 Archibald Geikie, Textbook of Geology (New York, 1902), p. 407. 



