758 



PRINCIPLES OF STRATIGRAPHY 



posed by me some time ago, and first used in print by Hahn (i8), 

 is enterolithic structure. 



What is believed by many to represent extreme cases of defor- 

 mation due to endogenetic causes is found in the remarkable salt 

 domes of Louisiana and eastern Texas, and of North Germany, es- 

 pecially in middle and northern Hanover and Brunswick, extending 

 as far as the Elbe. Similar occurrences are reported from Tran- 

 sylvania, on both sides of the Pyrenees, and from southern Algeria 

 (Fig. i6o). 



These "salt domes" are elliptical in section, with folded, often 

 much distorted layers of salt, gypsum, and in some sections potash 

 salts, which rise through the enclosing strata, deforming them, and 

 maintaining a plug-like relation to them. It is true that some writers 



Fig. i6o. Section and ground plan of a salt dome in the Moros Valley, 

 Hungary. (After Lamprecht in Fiirer's Salzbergbau.) 



(Stille, papers cited by Hahn-17) have explained these relation- 

 ships as due to repeated foldings, but the consensus of opinion 

 (Hahn-17) seems to be that, while some folding has imdoubtedly 

 occurred in certain places, the main force was the endogenetic one 

 due to the crystallizing force of the salts and to metasomatic proc- 

 esses. (Arrhenius-4.) 



Enterolithic structure is also a frequent occurrence in fine- 

 grained limestones or dolomites. A remarkably fine example is 

 seen in the basal "hydraulic" limestones of the Lockport series of 

 Siluric age, in a section opened by the canyon of Niagara. The 

 strata are finely shown along the railroad bed on the right bank of 

 the canyon. This structure is equally well developed (Fig. 161) in 

 the Upper Muschelkalk of the Neckar Valley, in Wtirttemberg, Ger- 

 many (Koken-22), and will probably be recognized in other forma^ 

 tions. The essential feature is here, as pointed out by Hahn, that 

 the deformation is in all directions,* not in certain ones, as would 



* The multi- gyro- and a-polar deformations of Lachmann. 



