123 



bility that life existed in the sea in which it was deposited ; 

 hut as lime must have formed a constituent of the waters of 

 the ocean before life was there to utilise it, and knowing the 

 rocks constituting the Adelaide chain and Munno Para to he 

 much older than the Silurians of Yorke's Peninsula, it is quite 

 possible that the material forming the marbles of our ancient 

 fundamental rocks was collected from the early water by 

 direct chemical agency. 



Quartz Reefs. 



Except the vast mass referred to at page 114 (if it be a 

 quartz reef), and one peeping out in a gully excavated 

 in the drift in Section 3036, and nests and strings frequently 

 occurring throughout the clay-slate, no other sign of quartz 

 reefs, in the true sense of the term, occurs throughout the 

 rocks on the western side of the watershed. 



On the South Para River, however, in Sections 3347 and 

 3348, a pure white quartz vein is seen trending in a north and 

 south direction, seemingly in conformity with the dip and 

 strike of the surrounding strata. Also another occurs in like 

 conformity with the general stratification in Section 1033. 

 Near this place in the bed of the river, the old alluvial work- 

 ings are situated, where gold in anything like paying quantities 

 was first discovered in South Australia, in 1850 ; and these 

 attracted the attention of a few until the advent of the gold 

 mania in Sydney and Victoria. Prom what I have been able to 

 gather of the nature and character of the gold found here, I 

 am inclined to think it was not derived from the adjoining 

 quartz reef, but had been transported hither from a distance, 

 probably from some extinct outlier of the gold-bearing Miocene 

 gravels of Barossa. 



Economic Purposes. 



Copper. — Slight indications of this metal have been found 

 staining the nests and strings of quartz distributed throughout 

 the clay slate. However, up to the present time no find has 

 been made of sufficient importance to induce a systematic 

 search. 



Iron. — An ore of this metal is indicated as occurring in 

 interstratification in the cross section. I am. nevertheless, not 

 yet quite convinced whether or not it is correctly so placed. 

 Surface indications, however, in Sections 3267 and 4146, and 

 elsewhere over the same line of strike, have induced me 

 strongly to infer that an interstratification of that mineral 

 occurs in the fundamental system near the place shown in 

 section, pi. vi., fig. 2. 



