TRANSACTIONS OF SECTION C, 66^ 



blende, though the appearance of the rock is not strilciuo'ly porphyritic, and the 

 general structure is very similar to that of the less basic syenite-porphyries of the 

 Charnwood district in Leicestershire. It points, in fact, to a hyp-abyssal as 

 opposed to a plutonic origin for the rock, which might therefore be classed as a 

 diorite-porphyry or hornblende-porphyrite. 



8. A^ote on some AntJiropods fro^n the Upper Sihirian, 

 By Malcolm Laurie. 



9. The Cop)per-bearing Rocks of South Australia. By F. P Mennell. 



The copper ores of Yorke's Peninsula in South Australia were the first 

 metallic minerals worked on the Australian continent. They occur in rocks of 

 Arcbtean ago, which at Moonta and Wallaroo have been subjected to crushing 

 and shearing to such an extent that they present few traces of their original 

 structures, except in the case of a diorite at "Wallaroo, which is of a typically 

 plutonic character. Most of the rocks are mylonites, and in some instances have 

 been reduced to a compact flinty type, in which none of the minerals can be 

 recognised with certainty. Where the original constituents have survived they 

 are of a fragmentary character ; oligoclase seems to have best resisted the crushing, 

 and orthoclase occasionally remains inlenticles ; but the brittle quartz has invari- 

 ably been reduced to powder. The economic aspect of the examination is of 

 considerable importance, for the mines have several times been shut down when 

 the ore has thinned out owing to doubts as to its permanence. From the 

 character of the rocks it is, howeA"er, obvious that they occur in a true ' fissure 

 lode,' and no doubts need be felt as to the continuance of the ore to the limit of 

 workable depths. 



10, Report on the Excavation of the Ossiferous Caves at Uphill, near 

 Weston-sup)er-Mare. — See Reports, p. 352, 



