1 88 THE POPULAR SCIENCE MONTHLY 



these monotonous marshlands are great swells of terra-firma, one hun- 

 dred or more feet in height and a mile or more in diameter. They are 

 seen from a great distance, and strike one at once as being something 

 out of the ordinary, surely formed by no common method of uplift, less 

 yet by circumdenudation. Of these coastal mounds the so-called " Five 

 Islands," lying to the east of Vermilion and Atchafalaya bays are 

 splendid examples. Belle Isle is just to the west of the Atchafalaya 

 Eiver, between Morgan City and the Gulf, Cote Blanche, Grande Cote, 

 Petite Anse and Cote Carline follow to the northwestward in the order 

 named. The first, or Belle Isle, is famous as the fabled residence of 

 Lafitte, the great Gulf pirate, Grande Cote and Petite Anse for their 

 salt mines and Cote Carline for the southern home of Joe Jefferson, the 

 actor. The drill has demonstrated the fact that these rounding hills 

 are the surface indices of salt masses below. Down one, two or three 

 thousand feet drills have penetrated with but little variation of matter 

 and structure, making, as already observed, the salt masses perhaps as 

 deep or deeper (thicker) than they are in horizontal diameter. Just off 

 the mound one may drill two thousand feet and encounter nothing but 

 soft clays and sand of Quaternary or " Recent " age. Below are similar 

 materials belonging to the Miocene Tertiary; there is no salt, some- 

 times not even salt water. Such strangely local salt lumps naturally 

 have troubled the philosophical geologist not a little. Some have said 

 they must have been formed in the crater of some dying volcano, sea- 

 waters having oozed in and evaporating deposited salt for years and 

 years in a streaming caldron. But alas for this explanation, these salt 

 masses are not simply the residue of evaporated sea water, they are 99 

 per cent, chloride of sodium and without the admixture of crater debris. 

 They are pure and solid. Again, though careful magnetic surveys have 

 been made about them, they fail to show any of those erratic local vari- 

 ations sure to occur in volcanic regions. Finally there is proof positive 

 they were never deposited in a hole or depression, but on the contrary 

 have even moved upward bodily through hundreds of feet of surround- 

 ing deposits! This seems at first absolutely impossible and as certainly 

 absurd. Nevertheless, we can demonstrate the point beyond doubt. 

 Note that we have said that certain of these salt lumps occur some dis- 

 tance from the Gulf coast, up country, so to speak, where the terranes 

 are of Tertiary and Cretaceous age and are more or less consolidated. 

 For example, in north central Louisiana salt comes near the surface of 

 the soil in circular areas. Surrounding these areas are rings of highly 

 tilted Cretaceous deposits, still outside are the lower Tertiaries, 1,000 

 or 1,200 feet thick. Clearly then these salt punches, so to speak, have 

 pushed themselves from amongst Cretaceous rocks right through the 

 Lower Tertiaries, bending these strata up on all sides of the mass, to a 

 height of 1,000 or 1,200 feet. The case then seems clear that the salt 



