29 
Lower Palaeozoic and Metamorphic {Azoic) Rocks . 
The normal or unaltered Lower Silurian rocks form the pre- 
vailing rock-foundation from westward of Ararat to a line ’from 
Melbourne to Heatlicote ; eastward of that line, and occupying 
the central eastern portion of the colony, appears the Upper 
Silurian group, the rocks of which are clearly recognisable as far 
eastward as a line ‘from the Moculister River, in Gippsland, to 
Benalla. The Silurian rocks eastward from that line have been 
indicated on the Geological Sketch-map as Lower Silurian, but, 
from recently acquired information, it appears likely that they are 
Upper Silurian as far eastward as Beechworth. 
The leading characteristics of the Lower Paheozoic rocks 
generally, iu Victoria, are the normal N.Wly. to N.N.Ely. strike, 
and the high rate of inclination of their bands, caused by the crump- 
ling or folding process to which they were subjected at a date 
probably not long subsequent to their deposition, as we find nearly 
horizontally-bedded rocks of Upper Palaeozoic age resting on the 
abraded up-turned edges of the nearly vertical Silurian strata. 
A statement of the gcuerally-accepted working theory as to the 
causes of this plication of the strata, and of other processes to 
which they have been subjected, may not be out of place here, 
for though familiar to most students of geology it may not be so 
to the general reader, and will serve to elucidate foregoing remarks 
as to the Plutonic rocks. In the first place, it is now recognised 
as a demonstrated fact that most stratified rocks are the results of 
the gradual deposit by the sea of matter once held by it in suspen- 
sion or solution, and origiually derived from the disintegration of 
pre-existing formations, and that, by the action of pressure, heat, 
chemical agencies, or whatever causes, these once soft and plastic 
sediments were indurated and converted into rock-masses. The 
results of astronomical and geological investigations combine to 
justify the belief that this earth was once in a state of intense 
heat, and in the condition of a molten mass environed by an 
at mosphere of gases ; that, gradual cooling, allowed the consolida- 
tion of a crust on the surface of the heated bulk, the formation of 
water by the union of its component gases and the descent of that 
water on the surface of the globe; and that from that epoch com- 
menced the work of deposit, denudation, and re-distribution of 
particles by aqueous action that has ever since been in unceasing 
progress. 
Whether this theory be correct in detail or not, it is very evident 
that a hardened crust of some description, on which the first 
aqueously-deposited strata could be laid down, must have been in 
existence, and that during the formation of these earliest sedi- 
mentary rocks conditions were present which do not obtain with 
regard to the deep-sea deposits now in progress. 
The earth was still in a highly -heated condition and of greater 
bulk than now; the water probably covered the entire surface, and 
c 
