Jenolan Caves. 
243 
These quarries are in an outlier of Upper Marine 
Sandstone. It will be noted that the sandstone in the 
quarries contains water -worn boulders of granite, 
quartz, and metamorphosed slates. The occurrence of 
granite boulders is especially interesting, as they prove 
that the granite is older than the Upper Marine ; and 
evidence is available elsewhere that the same granites 
are newer than Silurian, and, perhaps, even Devonian 
rocks. It is for this reason we are able to say that 
these granites are newer than Silurian and older than 
the Upper Marine beds of the Permo-Carboniferous. 
A few miles beyond the Half-way House referred 
to, the road follows a cutting around the head of a deep 
valley. Granite is exposed here, showing concentric 
and spheroidal weathering, with a distinct disposition 
to develop a sheeted structure. 
Fifteen and a-half miles from the Cox River we 
leave the granite, and in various places along the road 
quantities of water-worn pebbles and boulders will be 
noted. At first sight these would seem to be derived 
from some vast river deposit. On a closer examina- 
tion, however, it will be seen that these boulders are 
all that are left of extensive sheets of Upper Marine 
Sandstones and conglomerates removed from this 
region by denudation. In other words, these boulders 
owe their rounded character to the action of the sea 
in far-away Permo-Carboniferous times. They were, 
through long geological ages, embedded in a sandstone 
matrix which settled round them on the old sea-shore. 
They were buried beneath many thousands of feet of 
