364 
Miscellanea. 
greatest elevation is the double summit of Mount Pitt, 1,050 feet 
high; its sea-front is high and precipitous, presenting cliffs 200 
and 250 feet in height, and the small streams which occupy the 
ravines in winter, fall, in cascades 30 or 50 feet high, into the 
sea. Phillip Island is about 1 1 mile long, with an average breadth 
of Its most elevated point is probably two or three hundred 
feet less than that of Norfolk Island. It is everywhere preci¬ 
pitous, furrowed by deep channels, and densely wooded, though 
the timber is small and of little value. But these islands are 
masses of porphyry, much decomposed on the surface; boulders 
of compact greenstone are abundant in both islands, especially in 
the fields and watercourses of Norfolk Island, where they are em¬ 
ployed as building materials. They are also found imbedded in 
the porphyry at the greatest depths to which the rock has been 
penetrated by wells or exposed in ravines. Near the south-east 
extremity of Norfolk Island are extensive beds of sand and lime¬ 
stone resting on the porphyry; the limestone, which is the lowest 
formation, is from 12 to 20 feet thick, and occupies about 20 
acres of comparatively flat land ; in two places it has been frac¬ 
tured, and uplieaved from an angle of 10° to absolute verticality. 
It is thin-bedded, the laminm being usually one to three inches 
thick, of fine quality, slightly mixed with sand, but yielding 90 
per cent, of lime. The sandstone appears to be entirely a modern 
formation, lying upon and against the dislocated limestone; the 
bar and projecting rocks along the whole south-east front are 
composed of it, but it is nowhere above 6 feet thick; below it is 
found an unctuous black clay full of vegetable remains, especially 
the leaves and seeds of pines and other island trees. The sand¬ 
stone is only compact on the coast, where it is still forming; it 
contains marine shells, and incrusts the boulders of greenstone on 
the coast. Being porous, and filled with saline particles, it forms 
a bad building stone, the houses built of it requiring to be rough¬ 
cast with lime. Opposite the settlement which is placed on these 
beds, and about 600 yards from the beach, Nepean Island rises 
to the height of 50 feet; it is about a quarter of a mile long, and 
of a horse -shoe shape, open to the east. The limestone of which 
this island is composed is used for the shafts of chimneys; its east 
