iqo THE POPULAR SCIENCE MONTHLY 



strength of the grown crystal. Therefore we are sure growing crystals 

 of salt can lift a column of Gulf coast deposits at least 3,500 feet thick. 

 If brine is supplied to a salt mass from below, crystallization will take 

 place mainly on the bottom of the mass. Therefore the mass will grow 

 from bottom up. The top will be thrust through the superincumbent 

 beds, bending and tilting them up at high angles. Some growth would 

 doubtless take place on the sides of the mass till it attained consider- 

 able dimensions; afterwards it would be confined to the base, for the 

 column of rock salt would be a better conductor of heat than the sur- 

 rounding clays and sands, hence the marked change of heat, hence the 

 salt deposition would take place at the base of the salt column. The 

 mass would therefore be of comparatively small diameter, though its 

 depth might be great. 



We see from the above considerations how salt masses might be 

 formed and how they would by receiving their growth increments from 

 the bottom seem, to move upwards and pierce the superficial layers of the 

 earth's crust and there be truncated by atmospheric agencies if they 

 actually reached the surface, or how they might produce great weales on 

 the surface in case they did not quite pierce through. Now we wish to 

 give a few facts indicating that the process outlined above is truly that 

 by which these salt masses were formed and pushed up. Eeferring 

 again to Gulf-coast structural features, noting the location of all the 

 salt masses known to date, we have little difficulty in satisfying our- 

 selves that such masses are located in a rectilinear manner, row after 

 row as we approach the Gulf border. These lines are parallel in a gen- 

 eral way to fault lines farther up country in Arkansas and Texas. A 

 movement along a fault line, similar to these, most readers will re- 

 member caused considerable trouble in the region of San Francisco 

 but a few years ago. Where such lines cross (for in Louisiana there 

 are two sets) points of weakness occur permitting the upflow of artesian 

 waters. In several of the " mounds " these waters are saline and 

 " hot." 



Finally the source of the salt itself has been a subject of much spec- 

 ulation. However, it is a matter of no serious concern for us here. We 

 know that artesian conditions occur in the general region we are dis- 

 cussing, we know that there are breaks or fault lines and points of 

 weakness through which artesian flows may take place, we know that 

 deep artesian waters are always regarded as " hot." We know 

 that cooling saturated solutions of salt in water must be continu- 

 ally giving up salt; and as this crystallizes it forces aside and up- 

 wards superficial rock strata even to depths of several thousand feet. 

 Not only do we know it has strength to do this, but, best of all, there 

 in the Gulf region are the salt masses and there are the bent-up and 

 folded-back rocks. Still we may be permitted perhaps to speculate re- 



