22 
Geology and Physical Geography: 
nnd sandstones, resting on edge upon the granite which appears 
at the base of the slopes. These facts indicate that the presence 
of the granite cannot be immediately associated with any idea as 
to the nature of the forces which caused the general tilting, 
folding, and corrugation of the Lower Palaeozoic rocks ; and also 
that the granite, as we now 6ee it, could not have been the 
foundation on which those rocks wore originally deposited. 
The inferences are that after, or perhaps during, the plication, 
by whatever causes, of the Silurian rocks, an access of heat 
caused the fusion of their foundation at great depths below the 
then surface ; that this fused and plastic mass invaded and partly 
absorbed the lower edges of their folds ; that beyond the limits of 
such actual transmutation of the sedimentary strata into portion of 
the fused granitic mass, the former were metamorphosed by heat 
and other agencies combined for a greater or less distance from 
the igneous mass ; and that after this mass had cooled and con- 
solidated into granite under great pressure, and a great depth below 
the then surface, the action of denudation during subsequent 
periods removed portion of the superincumbent strata, and laid 
bare its more prominent projections. (Figs. 4 and .5.) 
Tig. 5. — Section showing contact of Granite and Silurian. — Tail Race oi? 
Kocky Mountain Gold Sluicing Company, Beecuworth. 
Much of our granite may, therefore (as indicated by Mr. Sehvyn), 
be regarded as completely transmuted Lower Palaeozoic strata ; 
but as this subject will be further dealt with in describing the 
metamorphic stratified rocks, the Plutonic igneous rocks allied to 
granite, but of somewhat different mineral combinations, will first 
be noticed. 
Among the areas represented as “ trap” on the Geological 
Sketch-map, the rocks in three, namely, those of Mount Macedon, 
flic Dnndenong Ranges, and Mount Juliet, besides others of minor 
extent, appear to be intimately associated with the ordinary 
granites, though the true relations of the rocks liavo not yet been 
properly investigated. In all three instances there seem to be no 
clearly -defined lines of demarcation between the rocks classed as 
