321 



section, might be referred to that type of intraformational 

 brecciation which Grabau has called ''subaquatic gliding- 

 deformation"; while the recemented angular fragments, that 

 form the top layer, agree equally well with Hyde's ''desiccation 

 breccias." 



The observations at Beltana were made in 1901, when 

 little was known of contemporaneous brecciation, or otherwise 

 I should have made a more careful examination of the 

 neighbourhood for further clues, and, unfortunately, I have 

 had no further opportunity of visiting the locality. 



Plate XX. has been introduced to illustrate how^ a 

 desiccation breccia might originate. 



DESCRIPTION OF PLATES. 



Plate XVI. 

 Hand specimen of brecciated and nodular chert. Upper 

 Torrens-Limestone. Lower Cambrian. Natural size. 



Plate XVII. 



Fig. 1. Vertical polished section of laminated and brecciated 

 limestone. Government ballast quarry, Burra. Lower Cajnbrian. 

 Natural size. 



Fig. 2. Polished face in diagonal direction to lamination 

 and at right angles to the face shown in jig. 1. 



Plate XVIII. 

 Fig. 1. Polished face taken parallel to lamination, in same 

 specimen illustrated on plate xvii., showing fiat faces of brecci- 

 ation. Natural size. 



Fig. 2. Another polished example from the Burra, showing 

 wavy and concentric structure. 



Plate XIX. 

 Example of pseudo-oolitic and brecciated limestone, Depot 

 Creek. Lower Cambrian. Natural size. 



Plate XX. 

 Sun-cracks in dried mud — the first stage in the construction 

 of a desiccation breccia. Mud flat at outlet of smaU creek, near 

 high- water mark, on Sellick Hill beach. 



Plate XXI. 

 Surface of impure limestone showing broken fragments of 

 calcareous sediments that have been recemented into the matrix, 

 probably a desiccation breccia. Beltana. Upper Cambrian. 

 Natural size. 

 k2 



