150 



THE ULTIMATE SOURCE 



supportable in brine of a certain density. In the Madras 

 salt works, it is found that the mollusca, Crustacea, fishes, &c. , 

 which find their way into the salt beds, whether voluntarily, 

 or through the agency of the lift pumps, begin to work 

 their way out expeditiously, by all possible channels, as 

 soon as the brine reaches a density of 5, or 6°, Beaume ; and 

 that at 7, or 8°, Beaume, those left behind, sicken and die, so 

 that at 9° Beaume, not a living animal is left in the briue. 

 At 7° Beaume, the sea water has been reduced, by evaporation, 

 to about one-half its original bulk, gypsum is depositing 

 and continues to deposit for some considerable time, until 

 the brine is reduced to one-quarter of its original bulk ; 

 but common salt has not formed, nor does it form until 

 long after, until but one-tenth of the original brine remains. 

 So that, if we imagine that all possible means of escape were 

 cut off from the inhabitants of our evaporating sea, and all 

 had perished, we should find their remains buried in the soft 

 mud under the gypsum, which would subsequently cover them 

 over with a thick deposit. But, there is reason to suppose that 

 the gradual elevation of salt areas was a protracted work 

 of time, in which opportunities were afforded for the 

 living contents of the rising estuary, or sea, to join the 

 main ocean, before evaporation had made the brine uninha- 

 bitable. We can easily conceive, how, at the first warning 

 of increase of density, every living creature would make for 

 the connecting straits and shallows, and dart into the great 

 ocean ; and how finally, some molluscs and crustaceans, 

 overtaken in their slow flight, would fall, die, and be buried, at 

 the extremity, or confines, of the shrinking sea, far away 

 from its central salt deposit. In point of fact, almost all 

 salt deposits do contain the fossil remains of a few speci- 

 mens of the marine fauna which existed at the date of their 

 formation, and not seldom in the rock salt itself ; from which 

 it may be argued, with a considerable approach to certainty, 



