208 
ECONOMIC GEOLOGY 
retains the potassium, magnesium chloride, and bromine. 
The ratio of magnesium to sodium is raised from 1 to 4 in 
the Jordan to 8 to 5 in the Dead Sea. The rate of this change 
can be inferred from the amount and composition of the 
Jordan water, and the age of the Dead Sea has been thereby 
~alculated as 50,000 years. 
Tue GerMAN Sart FIELDS—Some deposits of salt and 
B 
D 
ere 
Fig. 54.—GerMaN Savt FieLps. 
Diagrammatic section across the German salt fields, showing the general 
sequence and relations of the deposits. (Simplified from a section by 
Everding.) 
A = Werra type. B = Hanover type, 
C = 8S. Harz type, D = Stassfurt type. 
A. 
ii 
= 
ne 
Ex 
x 
Pre-Carboniferous and culm. 
Upper Carboniferous Rothliegende, lower Permian. 
Older primary rock-salt, 
Secondary rock-salt. : 
Younger primary rock-salt, 
Potash salts with their cover of clay. 
Main bed of anhydrite, 
Upper Zechstein, upper Permian, 
Bunter sandstones, lower Trias. 
gypsum have been formed by the simple evaporation of 
sea-water which has been cut off in lagoons; such are the 
layers of gypsum found on coral islands, and the lenticular 
patches of salt in the Permian red rocks of Kansas and the 
salt beds of Cheshire. The most important salt field is that 
of Central Germany, and its story, as illustrated by Fig. 54 
may be summarized as follows. An ancient land, composed of