4i8 



EDWARD STEIDTMANN 



The average calcium to magnesium ratio of these streams is 

 between 2 . 5 and three. The ratio of calcium to magnesium of a 

 normal dolomite is 1.61; that of an average shale 1.47 (Clarke). 

 The calcium to magnesium ratio of the streams is probably higher 

 than that of the terranes through which they flow. 



An average of five water analyses on phyllite reported by 

 Hanamann shows a ratio of calcium to magnesium equal to 2.37. 



The stream waters from limestone areas show a high calcium 

 ratio. See Table XXII. 



TABLE XXII 

 Table Showing the Calcium Magnesium Ratio in Streams Flowing over 



Limestone 



The following table of averages suggests the influence of the 

 terrane on the run-off. 



TABLE XXIII 



The influence of climate on the calcium magnesium ratio of 

 streams. — Clarke 1 has pointed out that the streams of humid, 

 more or less forest-covered portions of North America are normally 

 carbonate waters in which calcium is the principal base, while 

 rivers in arid climates tend to be high in sulphates and chlorides 

 in which calcium may or may not be the principal base. The 



1 F. W. Clarke, Bull. 330, U.S.G.S., 72. 



