.112 



From the foregoing it will be noticed my argument favours 

 the theory of marine origin. And although the only fossil 

 hitherto discovered in the Upland Miocene is silicified wood, 

 yet its presence is no proof of a purely lacustrine origin of the 

 deposits, inasmuch as terrestrial vegetation has been frequently 

 found associated with indubitable marine fossils. So far as I 

 know, the Upland Miocenes of Munno Para have not pro- 

 duced a single specimen of silicified wood, though it has been 

 procured from the debris of a neighbouring outlier in Para 

 Wirra. Indeed the marine beds at Gawler seem to be the great 

 emporium of these ancient vegetable relics, and from careful 

 observation I am led to conclude these chiefly grew near the 

 spot where they are now found. 



Relation to the Auriferous Cements of Barossa and Humbug 

 Scrub. — That the deposition of the Upland Tertiary beds of 

 Munno Para and the auriferous cements of Victoria Hill and 

 other old gold-bearing gravels of Barossa and Humbug Scrubs 

 belong to the same geological period a doubt cannot be enter- 

 tained. Ascending from Grawler, they can be traced overlying 

 at intervals the rugged surface of the old rocks, until at the 

 Victoria Hill and Lady Alice Mine they attain an altitude of 

 about 950 feet. Indeed their relationship is so easily read and 

 defined in that respect that in cases where altitude coincides 

 deposition may be regarded as having been contemporary. 



"Why the easterly tracts of the Upland Miocenes have become 

 more auriferous than those in Munno Para may be attributed 

 to a higher state of metamorphism prevailing throughout the 

 fundamental rocks to the east. 



Fundamental Bocks. 



Supposed Age. — Until the appearance of Mr. Tepper's 

 " Bocks and Cliffs of Ardrossan," the fundamental rocks con- 

 stituting the Adelaide and Flinders Eanges and other minor 

 groups traversing the southern sea-board of South Australia 

 were considered by the most eminent authorities to be not 

 older than Silurian. Mr. A. B. C. Selwyn, in his report to the 

 South Australian Government of a G-eological Tour in this 

 Colony in 1859, in his usual careful way of expression, sup- 

 ports that hypothesis. Basing his conclusions from natural 

 sections of the country, they are : — 



That an unconformable series tops the summits of a large 

 number of the highest of the South Australian hills. The 

 higher series he regards as of Devonian age, and in the absence 

 of fossils he concludes that the unconformable subterimposed 

 beds belong to the system next in point of time, viz., the 

 Silurian. 



In 1866 — " Physical Geology of Victoria," page 16 — whilst 



