"The south and south-eastern extremes of Clack's Island presented a
steep, rocky bluff, thinly covered with small trees. I ascended the steep
head, which rose to an elevation of a hundred and eighty feet above the
sea. I found simply the plants of the main, namely, Mimusops parvifolia,
Br.; Hoya nivea, Cunningham manuscript; Acacia plectocarpa, Cunningham
manuscript; Chionanthus axillaris, Br.; Notelaea punctata, Br.; some
alyxiae, and the small orange-fruited ficus, which grew in the thickets,
and, by insinuating its roots in the interstices of the rocks, clothed a
great portion of the inaccessible front of the island.

"The remarkable structure of the geological feature of this islet led me
to examine the south-east part, which was the most exposed to the
weather, and where the disposition of the strata was of course more
plainly developed. The base is a coarse, granular, siliceous sandstone,
in which large pebbles of quartz and jasper are embedded: this stratum
continues for sixteen to twenty feet above the water: for the next ten
feet there is a horizontal stratum of black schistose rock, which was of
so soft a consistence, that the weather had excavated several tiers of
galleries; upon the roof and sides of which some curious drawings were
observed, which deserve to be particularly described: they were executed
upon a ground of red ochre (rubbed on the black schistus) and were
delineated by dots of a white argillaceous earth, which had been worked
up into a paste. They represented tolerable figures of sharks, porpoises,
turtles, lizards (of which I saw several small ones among the rocks)
trepang, star-fish, clubs, canoes, water-gourds, and some quadrupeds,
which were probably intended to represent kangaroos and dogs. The
figures, besides being outlined by the dots, were decorated all over with
the same pigment in dotted transverse belts. Tracing a gallery round to
windward, it brought me to a commodious cave, or recess, overhung by a
portion of the schistus, sufficiently large to shelter twenty natives,