310 



2. By Gravitational Deformations: — 



(a) Subaquatic Gliding-deformations (Hahn, 



1912; Grabau, 1913). 

 (h) Edgewise Conglomerates (Hahn, 1912). 



3. By Ice Movements: — 



Glacial Breccias, etc. 

 II. ExoGENETic (Internal Deformation subsequent to Con- 

 solidation). 



1. By Chemical Change: — 



Enterolitbic Structures by hydration, dehydra- 

 tion, substitution, etc. (Hahn, 1912; 

 Grabau, 1913). 



2. By Dynamic and Tectonic Movements: — 



(a) Autoclastic (Smythe, 1891). 



(h) Friction Conglomerates (Van Hise, 1893). 



(c) Crush Breccias and Conglomerates (Lamp- 



lugh, 1895). 



(d) Intraformational Conglomerates (Walcott, 



1896). 



(e) Dynamic Breccias (Van Hise, 1896). 



(f) Pseudo-conglomerates (Van Hise, 1896). 



(g) Thrust-conglomerates (Gardiner and Rey- 



nolds, 1897). 

 (h) Fault and Vein Breccias. 



South Australian Examples. 



Crush zones, conglomerates, and breccias of different 

 types occur at various horizons in South Australia, Some 

 of these are evidently dynamic in their origin, while others 

 can, with considerable probability, be referred respectively 

 either to chemical changes that have transpired within a rock 

 mass subsequently to its induration, or to a process of 

 desiccation and displacement that occurred contemporaneously 

 with its deposition. In some cases the causes of such internal 

 deformations are obscure. 



As in other parts of the world, the beds in which the 

 deformations have taken place are mostly limestones, which, 

 in some cases, are somewhat thinly laminated and others are 

 massive. Limestones are particularly liable to chemical 

 interchanges, both with respect to molecular structure and 

 chemical substitutions. Many of the Cambrian limestones 

 of South Australia have been greatly altered by the 

 interpenetration of silica, either in the form of a diffused 

 silica-skeleton, or as layers of chert that are often closely 

 interlaminated with thin layers of limestone; also by the 



