118 E. F. PITTMAN. 



account of the presence of alkaline carbonates in the water, 

 and it cannot be admitted for one moment that the presence 

 of those substances is any proof of plntonic origin. In the 

 first place there is nothing unusual in artesian water con- 

 taining alkaline carbonates. Thus, some of the artesian 

 well waters of Iowa contain these salts. 1 The artesian 

 waters of Texas contain much alkaline carbonates ; the 

 average solid contents of these waters from six localities, 

 from Port Worth southwards, are given as follow: — 2 



Chlorides (chiefly Na) 12,707 grains per gallon 

 Carbonates ,, 20,750 ,, ,, 



Sulphates ,, 21,464 ,, ,, 



51,921 

 These water-bearing beds, the "Trinity Sands," are at 

 the base of the Lower Cretaceous system. The artesian 

 waters ol' the Cretaceous basin of Alabama also contain 

 considerable quantities of alkaline carbonates. -1 



But in any rase it is unnecessary to go to any plutonic 

 depths to discover the source of the alkaline carbonates 

 in the Australian basin, for it will be revealed by a slight 

 examination of the porous beds where they outcrop at the 

 surface. The Triassic sandstones have all the appearance 

 of having been derived from the disintegration of granites. 

 They consist of grains of quartz with a very felspathic 

 looking cementing material. It is a fair assumption that 

 the granites contained soda- and potash-felspars, the decom- 

 position of which would yield just such a clay, aud, as a 

 matter of fact, analyses recently made in the Geological 

 Survey laboratory of two samples of the porous sandstone 



1 Iowa Geological Survey, Vol. vi., 1897. 



2 Twenty-first Ann. Rept. U. S. Geol. Sur. Part vn., 1899-1900, p. 448. 



3 The Underground Water Resources of Alabama, E. A. Smith, Geol. 

 Sur. of Alabama, 1907, pp. 361-362. 



