hich the first expedition
travelled, it could hardly have been expected that its geological
specimens would be numerous. It will appear, however, from the following
list of rocks collected during the second expedition, that the geological
formation of the mountains to the S.W. of Port Jackson is as various as
that to the N.W. of it is mountainous. The specimens are described not
according to their natural order, but in the succession in which they
were found, commencing from Yass Plains, and during the subsequent stages
of the journey.

Sandstone, Old Red.--Found on various parts of Yass Plains.

Limestone, Transition.--Colour dark grey; composes the bed of the Yass
River, and apparently traverses the sandstone formation. Yass Plains lie
170 miles to the S.W. of Sydney.

Sandstone, Old Red.--Again succeeds the limestone, and continues to the
N.W. to a considerable distance over a poor and scrubby country, covered
for the most part with a dwarf species of Eucalyptus.

Granite.--Colour grey; feldspar, black mica, and quartz: succeeds the
sandstone, and continues to the S.W. as far as the Morumbidgee River,
over an open forest country broken into hill and dale. It is generally on
these granite rocks that the best grazing is found.

Greywacke.--Colour grey, of light hue, or dark, with black specks.
Soft.--Composition of a part of the ranges that form the valley of the
Morumbidgee.

Serpentine.--Colour green of different shades, striped sulphur yellow;
slaty fracture, soft and greasy to the touch. Forms hills of moderate
elevation, of peculiarly sharp spine, resting on quartz. Composition of
most of the ranges opposite the Doomot River on the Morumbidgee, in
lat. 35 degrees 4 minutes and long. 147 degrees 40 minutes.

Quartz.--Colour snow-white; formation of the higher ranges on the left
bank of the Morumbidgee, in the same latitude and longitude as above;
showing in large blocks on the sides of the hills.

Slaty Quartz, with varieties.--Found with the quartz rock, in a state
of decomposition.

Granite.--Succeeds the serpentine, of light colour; feldspar decomposed;
mica, glittering and silvery white.

Sandstone, Old Red.--Composition of the more distant ranges on the
Morumbidgee. Forms abrupt precipices over the river flats; of sterile
appearance, and covered with Banksias and scrub.

Mica Slate.--Colour dark brown, approaching red; mica glittering.
The hills enclosing Pondebadgery Plain at the gorge of the v