257 
90,000 ft., and that “this thickness is not a moiety of the 
whole." * 
Mr. H. Y. L. Brown, Government Geologist, in his Annual 
Report, 1883, published a general outline of the geology of 
South Australia, accompanied by a geological map and sec- 
tions. A revised edition of the map was published in 1886, 
in which the following order of the older rocks was given : — 
PaLmozoic—(?) Devonian. Tent Hill formation, west of 
Port Augusta. 
Parmozorc.—Lower Silurian. Clay slates, quartzites, 
limestones, etc., from Cape Jervis to Mount Babbage, etc. 
PALAOZOIC ов AZOIC.—Metamorphic. Mica and talcose 
schists, quartzites, crystalline limestones, etc. 
ÅRCHÆAN. —Metamorphic granite. Gneiss, hornblende, and 
mica schists, crystalline limestones, etc. 
These divisions are represented on Mr. Brown’s map in 
three parallel bands of colour, and the descending order of 
the beds is indicated as occurring in their passage from west 
to east. 
The geology of the Mount Lofty Ranges is further illus- 
trated by Mr. Brown, in his report, by a sketch section 
across the ranges from Adelaide to Strathalbyn. There is, how- 
ever, an apparent discordance between Mr. Brown's map and 
section. Whilst the former shows an order of succession in 
which the older beds occur on the eastern side, the section 
shows the lowest beds to occur on the western side. A regu- 
lar south-easterly dip is shown, in the section, from the west 
coast to the Onkaparinga River, from which position the 
upper beds, in isoclinal foldings, continue to their eastern 
limits. 
As opposed to the monoclinal theory of Professor Tate, Mr. 
Brown says:-— “The general dip of the rocks comprising the 
Mount Lofty Range is to the south-east, and, as it con- 
tinues eastward for a distance of some twenty miles, the 
thickness therefore indicated of the entire mass would be 
immense. The occurrence of dykes and masses of granitic 
rocks here, coupled with those to the north, as well as east- 
ward and westward in other parts of the colony, indicate, T 
think, the probability of granite and other plutonic and 
igneous rocks underlying the sedimentary rocks at a certain 
depth underneath the whole area, either as eruptive or 
metamorphic masses. In this case faults and inversions of 
the strata must have taken place, which will account for the 
position of the beds and their apparent great thickness." 1 
Op cb. p. xhv. 
T Ann. Rep. Govt. Geol., Parl. Paper, 1883, p. 10. 
Q 
