255 
Thirteen years later (1872, George H. F. Ulrich, late 
Senior Field Geologist to the Geological Survey of Victoria, 
reported to the South Australian Government on “the 
mineral resources of the country lying within 250 miles north 
of Port Augusta."* This author does not discuss the geo- 
logy of the Mount Lofty Ranges in detail, but he corrects 
Selwyn's observations in one particular. He states: —“I 
agree with Mr. Selwyn, for the same reasons he advanced, 
in unhesitatingly assigning them (the rocks) to one of the 
older epochs of the palæozoie period—the Lower Silurian being 
perhaps the most likely one. Owing, probably, to my rapid 
mode of travelling, I was not able, however, to recognise the 
features upon which Mr. Selwyn based their subdivision into 
older and newer; for throughout the country traversed, from 
the Burra northward, Isaw no evidence of any unconformity 
in the strata (the unconformable limestone patch noticed at 
the Sliding Rock Mine being, no doubt, much more recent) ; 
they seemed to me to represent one and the same grand 
series, only in places more or less metamorphosed by contact 
with intrusive rocks, as at Yudanamutana, near Mount 
Emily, Mount Plantagenet, and, perhaps, in a number of 
other localities. 
Little further attention was given to the geological сһагас- 
teristies of the fundamental rocks of South Australia until 
the late Professor Ralph Tate entered upon his duties as Pro- 
fessor of Natural Science in the Adelaide University in 
1876. In the following year Tate delivered a series of ten 
lectures under the auspices of the University on “The Ancient 
Physical Geography and Geology of South Australia." In the 
succeeding year (1878) he placed his views on permanent 
record by a fuller exposition of his conclusions on the geologi- 
cal outlines of the colony in a Presidential address, + delivered 
before the Philosophical Society of Adelaide. In his scheme 
Tate divided the older rocks into two main divisions, viz.:— 
(a) Pre-Silurian, and (b) Lower Silurian. He was led to 
these determinations mainiy by the discovery made, shortly 
before, by Mr. J. G. O. Tepper, of a fossiliferous limestone of 
paleozvic age at Ardrossan, Y.P. Tenison Woods? had pre- 
viously advocated. the Silurian age of the Mount Lofty 
Ranges, in reply to whom Tate said: —§ “Recent discoveries, 
which have been communicated to this Society by Mr. Tep- 
per, necessitate their relegation to a much more ancient 
* “Mineral Resources North of Port Augusta." Parl. Paper, 
(NGHGS), 18792 р. 15: 
+ Trans. and Proc. of Phil. Soc. of Adelaide, vol. ii., 1878-9, 
р. xxxixi 
t "Geological Observations in South Australia," pp. 20, 21. 
S res, Ad. Op. ot, p. xlv. 
