GEOLOGY OF THE PROVINCES OF BARAHONA AND AZUA. 



191 



at that time as 2 feet (61 centimeters) above sea level. Although his esti- 

 mates of altitude were made with a barometer and are therefore only 

 approximately accurate it would seem that there has been very considerable 

 evaporation since his map was prepared. According to Tippenhauer 1 

 the surface of the water was 34 meters below sea level in 1900. 



The water is nearly 50 per cent more saline than sea water. The accom- 

 panying analyses show that its composition is in general similar but that 

 the ratio between calcium and magnesium is reversed. Although Lake 

 Enriquillo was undoubtedly at one time an arm of the sea its water has 

 since then been considerably concentrated by evaporation, which is high in 

 this region, for it has no outlet. The drainage from the surrounding lime- 

 stone mountains has caused an increase in the percentage of calcium. 



Mineral analysis and classification of water from Lake Enriquillo near Barbacoa, Province 



of Barahona. 

 [Sample collected by C. P. Ross, May 29, 1919. Analyst, Addie T. Geiger.] 



Milligrams 

 per liter. 



Calcium (Ca) 1,649 



Magnesium (Mg) 378 



Sodium (Na) 15,973 



Potassium (K) a 503 



Carbonate radicle (C0 3 ) . 



Bicarbonate radicle (HC0 3 ) 512 



Sulphate radicle (S0 4 ) 3 ,833 



Chloride radicle (CI) 25,547 



Foaming constituents (computed) 44,000 



Alkali coefficient (inches) (computed) . 1 



Organic matter 270 



Total dissolved solids at 180° C 48,902 



a Equivalent to 0.0006 per cent potash (K2O) in liquid brine or 1.23 per cent K2O in total solids. 



Comparison of the composition of ocean water with that of Lake Enriquillo. 



[Percentage of dissolved solids.] 



a Analysis made in water resources laboratory of U. S. Geol. Survey. 



b Clarke, F. W., Data of geochemistry: U. S. Geol. Survey Bull. 616, p. 123, 1916. 



'Tippenhauer, L. G., Beitrage zur Geologie Hai'tis, V: Petermann's Mitteilungen, Band 47, VII, p. 

 169, 1901. 



