File:The Quarterly journal of the Geological Society of London (13206129644).jpg

1847.. JUKES ON AUSTRALIA. 247
Fig. 1.
fni'ii*ivifii,i \i
A parallel instance was observed in the cliffs a little to the east-
ward of the entrance of Port Arthur.
It appears then that there are masses of greenstone both of more
ancient and more modern date than the palaeozoic rocks.
At Macquarrie Plains, about ten miles above New Norfolk, there is
a large exhibition of igneous rock, which from its cellular character
seems certainly to have flowed as lava in the open air. It forms a
mass of considerable thickness, as shown in the brooks and ravines, and
appears to have been gradually accumulated by successive accessions
of melted matter. I infer this from the fact of its including fossil
trees, apparently in the position of growth, which seem to have been
enveloped while living in the lava.
There are two small patches of tertiary travertinous limestones:
one mentioned by Mr. Darwin, and found in the outskirts of Hobar-
ton, where it appears to have been tilted by the intrusion of an ad-
jacent mass of trap ; another in a little cove called James's Bay about
three miles above Hobarton, on the opposite side of the Derwent.
It rests here nearly horizontally, and is but little elevated above the
level of the sea. A Helix and a Bulimus, and the leaves and portions
of the stems of several plants, have been found in each locality.
Fossils from Jameses Bay.
Plants, unnamed : one figured by Morris.
Helix.
Bulimus.
There are very thick masses of gravel, consisting of pebbles as large
as the fist, accumulated on the sides of the Derwent River at some
places, and Count Strzelecki mentions great accumulations of loose
sand from beneath which he procured a large Cyprsea. This was at
Newton, a short distance from Hobarton.
B. Norfolk Bay and TasmarHs Peninsula.
The principal mass of Tasman's Peninsula appears to be columnar
greenstone, forming the highest and most rugged of its hills, and the
gigantic perpendicular chffs of Cape Pillar and Cape Baoul and the
intermediate shores round the entrance to Port Arthur. Just to the
eastward of the mouth of that harbour, a mass of the sandstone of
the palaeozoic formation, a quarter of a mile across and 200 feet high,
may be seen resting against these perpendicular cliffs of columnar
greenstone with its beds quite horizontal and apparently unaltered.