ations
of sand but huge blocks of rock, scarcely worn by attrition, occur in
great abundance in the bed of the stream; neither do we find in the
larger channels of the rivers below any sand deposits, but on the
contrary the very rich alluvium which distinguishes the banks of the
Hawkesbury.

(*Footnote. This book is already almost too full of plates and I beg to
refer the geological reader to my three-sheet map of the Colony for the
superficial forms and extent of these valleys.)

WELLINGTON VALLEY.

In the year 1830, after I had traced out the new line of descent from the
Blue Mountains to the interior country by the pass which I then named
Mount Victoria, I extended my survey to the heights beyond Wellington
Valley. This includes a rich alluvial tract watered by the river Bell,
one of the principal tributaries of the Macquarie, and is about 170 miles
to the westward of Newcastle. It is bounded on each side by a compact
calcareous rock resembling the mountain limestone of England and rising
on the east side to about 100 feet above the Bell.

On the west side of this valley hills of greater elevation, consisting of
a red sandstone and conglomerate, extend parallel to the limestone; and
on the east side of it is another range composed of trap-rocks. The basis
of a tract still further eastward, dividing the watershed of the interior
from that which sends its streams to the sea is, as has been already
observed, of granite.

The limestone presents a naked and rugged surface composed of pointed,
weather-worn blocks between which are small crevices leading to caves and
fissures. From these crevices a warm air ascends, accompanied by a smell
peculiar to the caves. The worn aspect of the external rock, resembling
half-dissolved ice, is very remarkable, particularly near the largest
caverns.

An account of the survey of these caves was communicated to the
Geological Society in a paper read on the 13th of April 1831, of which an
abstract was published in its Proceedings, but the particulars respecting
the animal remains found by me have derived great additional importance
from the discoveries made by Professor Owen since my return to England. I
may be excused therefore for again calling attention to the situation of
those curious caves respecting which the following details are now
published with the consent of the Council of the Society.

LIMESTONE CAVERNS.

The entrance to the caves of Wellington Valley is in the side