THE BAHAMA ISLANDS 171 



GRAVIMETRIC ANALYSIS OF WATER-SOLUBLE SALTS IN BRACKISH SWAMP OR 



SALINA. 

 Constituents. Per cent. 



Calcium sulphate (CaSO 4 ) 15 



Magnesium sulphate (MgSO 4 ) .07 



Magnesium chloride (MgCl 2 ) .15 



Potassium chloride (KC1) 19 



Sodium bicarbonate (NaHCO 3 ) 49 



Sodium chloride (NaCl) 39 



Total per cent of soluble salts 1.44 



The total amount of salts is seen to be so large that the cultivation of 

 any ordinary crop on this type would be impracticable. There is sufficient 

 sodium chloride present to prevent the growth of all ordinary vegetation. 



BAHAMA WHITE MARL. 



The Bahama White Marl did not occur on any of the islands mapped, 

 but was seen in a reconnoissance of Andros, of which it covers the western 

 half. It is reported also to be present upon a number of the islands, and to 

 occupy large areas. 



It is low-lying and swampy, and is often covered partially or wholly by 

 salt or brackish waters, and the only vegetation is that which is more or less 

 resistant to salt in the soil. The lower lying portions are covered with a 

 sparse growth of mangrove, while the higher portions, where there is soiife 

 drainage, support a few scrubby pines and palmettos, with a few other bushes 

 and sedges. 



The formation is a white coral material or coral ooze, so finely com- 

 minuted that it is almost an impalpable powder, and is very much like 

 chalk. Upon drying, this material contracts into blocks. The material has a 

 depth of from 1 to 3 feet, and is underlain by the same material solidified. 



At present it has no agricultural value whatever, and is in fact noted for 

 its unproductiveness. 



The analysis of a typical sample of the marl gave the following results : 



CHEMICAL ANALYSIS OP BAHAMA WHITE MARL. 



By acid digestion (HC1 sp. gr. 1.115). 

 Constituent. Per cent. 



Potash (K 2 0) 0.306 



Soda (Na 2 0) 2.12 



Lime (CaO) 47.50 



Magnesia (MgO) 2.85 



Iron and Alumnia (Fe & Al) trace. 



Nitrogen (N) 0.054 



Phosphorus pentoxide (P 2 O 5 ) 0.123 



Sulphur trioxide (SO 3 ) 0.37 



Chlorine (Cl) 2.97 



Silica (SiO 2 ) 3.22 



Carbon dioxide (CO 2 ) 40.48 



99.993 

 Oxygen equivalent of Cl .67 



99.323 



