IMMENSE SALT CONCRETIONS 189 



masses have come from below and have moved upwards. This is as 

 clearly demonstrated as the fact that the battleship Maine was wrecked 

 from a force without "because the plates were bent inwards." Were 

 the Tertiary and Quaternary beds removed from the flanks of these salt 

 masses we should see a cylinder or perhaps more accurately a truncated 

 cone of salt standing upon mid-Cretaceous rocks towering upwards half 

 a mile or perhaps a mile, though the upper end of the cone might not 

 be over |- mile across. Some one will say that is certainly similar to the 

 church-spire spur that was lifted out of the crater of Mt. Pelee after 

 its recent destructive eruption. Others will be reminded of Bogoslof 

 Island in Alaskan waters. But here again, in endeavoring to explain 

 the phenomenon there is no need of invoking vulcanicity. For the past 

 ten years we have had exceptional chances to study all these interesting 

 salt masses and are prepared to confidently affirm that the origin of 

 both salt masses and their movements has nothing to do with volcanic 

 action. 



The true explanation of the origin, growth and movement of these 

 salt masses seems simple when once we have a clear understanding of 

 certain structural features of the lower Mississippi region. Observe on 

 any geological map that Quaternary and older rocks back to the medi- 

 eval or Cretaceous beds all slope Gulf-wards at a much greater angle 

 than the surface of the ground makes with the horizontal. In other 

 words, if water should enter a pervious Cretaceous or older bed in 

 Arkansas and follow the same to the latitude of the Gulf border it 

 would find itself several thousand feet below the Gulf level. Such 

 waters would naturally become very warm as compared with water at 

 or near the surface. They would take soluble substances in solution. 

 If a break or point of weakness occurred in the superincumbent beds 

 such hot waters would ascend after the manner of water in an artesian 

 well. If the waters were saturated with salt at a high temperature they 

 would be obliged to part with some of their saline burden as they ap- 

 proached the upper, cooler strata. The amount of salt held in solution 

 by water at various temperatures, it is true, increases not greatly with 

 increased heat; nevertheless, it is appreciable, and in the end the giving 

 up of salt by lowering temperature would produce notable results. 

 Again, though salt masses might tend to accumulate as just outlined at 

 a certain place in the crust of the earth, would not pressure prevent 

 such a growth, and even if growth takes place what would tend to push 

 the salt up bodily say 1,000 feet or more ? Here again we need none of 

 Vulcan's aid, for we all know that when once crystallization com- 

 mences each little crystal will have its growth in spite of almost any 

 resistance. Witness the growth of ice crystals in our water pipes in 

 zero weather. In other words, the force exerted by growing crystals is 

 known to be at least of the same order of magnitude as the crushing 



