284 University of Calif orma Publications in Geology [Vol. 13 



Also: 



In conclusion it is believed that water in quantities sufficient to supply an 

 ascending circulation can only exceptionally attain a depth of 10,000 feet and 

 that, except in regions of great dynamic movements, the active circulation is con- 

 fined to the uppermost few thousand feet. More commonly the depth of active 

 circulation is measured by the level of surface discharge and the water below 

 that level is practically stagnant; the lower limit of the body of stagnant water 

 then forms an irregular surface descending to greater depths along the fractures 

 and rising higher in the intervening blocks of solid ground. 



Iii regard to the magmatic origin of mineral bearing waters Lind- 

 gren says in a later chapter : 13 



The water existed in the solution constituting an igneous magma. Crystalliza- 

 tion of the magma or its irruption into higher levels of the earth 's crust liberated 

 the water as one of the most volatile constituents, thus permittinig its ascent to 

 cooler regions. Such water may be called magmatic or juvenile. 



Then : 



Volcanic phenomena are almost always accompanied by the emissions of large 

 quantities of steam and other volatile substances, and geologists generally have 

 agreed that part of this water is a contribution to the atmosphere and hydro- 

 sphere from the magmas Regarding plutonic rocks the direct evidence 



is lacking but indirect testimony is supplied by the inclusions of aqueous solutions 

 found in granular rocks and by the presence of minerals like mica and amphibole 



which contain the hydroxy 1 molecule The best general evidence of the 



existence of juvenile waters is furnished, not by observation of the present springs, 

 but by the study of old intrusive regions. Here the granites merge into pegmatite 

 dikes, the latter change into pegmatite quartz, and this into veins carrying quartz 

 and metallic ores, such as cassiterite and wolframite. Here we have evidence 

 difficult to controvert that dikes consolidated from magmas gradually turn into 

 deposits the structure and minerals of which testify to purely aqueous deposition; 

 this admitted, it is difficult to see what would prevent such waters from reaching 

 the surface in the form of mineral springs. . . . The constant admixture with 

 vadose waters forms another difficulty, but accounts well for the many derivatives 

 of varying characteristics which accompany every spring of deep-seated origin. 

 . . . . Much more work must be done before we shall be able to establish the 

 magmatic origin of any given spring. 



J. F. Kemp 14 in general agreement with Lindgren, argues that at 

 varying depths below 10,000 feet the friction resistance offered to the 

 flow of ground water in fissures must seriously limit its mobility and 

 the quantity which can descend or flow laterally ; while at higher levels 

 the significant circulation of descending waters, in so far as they move 

 in notable volume, must be confined chiefly to fissures. On the basis 

 of experiments performed by himself he points out that the volume 



« Chap. VI, p. 87. 



i± The problem of the metalliferous veins, Econ. Geol., vol. 1, no. 3, p. 225, 

 Dec. -Jan., 1906. 



