[Proc. Rot. Soc. Victoria, 27 (N.S)., Part II., 1914]. 



Art. XIX.— 0?i the Occurrence of Igneous Pehhles in a Con- 

 glomerate of Upper Silurian Age from near Walhalla. 



By NORMAN K. JUNNER, B.Sc. 



(With Plate II.) 

 [Read 12th Novemlier, 1914]. 



Introduction. 



During a short visit made to Walhalla in June, 1913, with the 

 primary purpose of studying the relations between the auriferous 

 quartz reefs and the intrusive rocks there, my attention was 

 drawn, through the medium of a description in Mr. Herman's 

 report on the Walhalla Gold-field, i to an interesting conglomerate, 

 containing pebbles of igneous rocks, which was interbedded with 

 limestones, shales and grits of Yeringian age. It was at onc^ 

 evident, from a cursory examination of the conglomerate, that 

 Mr. V. R. Stirling's idea^, of an immense fault and associated 

 fault breccia was untenable; and further that the igneous pebbles 

 had no genetic connection with the so-called diorite dykes which 

 are so characteristic a feature at Walhalla. 



Many of the pebbles showed very little in hand specimens, and 

 it was only after sectioning them that their interesting nature 

 was revealed. Unfortunately, the time at my disposal was rather 

 limited, and my examination of the conglomerate and collection 

 of pebbles were not as detailed and thorough as they might have 

 been . 



Previous Literature. 



In 1878, Mr. R. A. V. Murray^ noted the presence of grits 

 associated with the limestone near the Thomson river, but did 

 not mention the occurrence of igneous detritus in the grits. 



In 1899 Mr. V. R. Stirling* described a belt of bieccia occur- 

 ring near the Thomson river copper mine. According to him 



1 " Report on the Walhalla Gold-Field." Spec. Rept. Dept. Mines, Vict., 1901. 



'i "Notes on alleged Copper Occurrences at Cooper's Creek." Monthly Pro(f. Rep. Vict. Geol. 

 Siuv., No. 2, 1899. 



;i I'log. Rep. Vict. Geol. Surv., No. .1, p. 4". 



4 "Notes on alleged Copper Occurrences at (.'oopei's Creek." Moiithly I'luy Kep. \ict. Surv. 

 No. 2, 1899. 



