HONG-KONG. 
61 
of other plants. I was unable to reach the summit of the mountain 
in consequence of the excessive heat, which at eight o’clock in the 
morning raised the thermometer in the shade to 83°, whilst the sun’s 
rays, to which I necessarily exposed myself, darted through an un- 
clouded atmosphere with an almost intolerable effect, and raised the 
quicksilver to 120°. I ascended about one thousand feet, and returned 
by a path which passed over a small hill, or rather mound, differing 
in structure from all the rocks in its neighbourhood, being composed 
of a very friable stone of a reddish white colour, much resembling 
disintegrated felspar. 
On reaching the shore, I examined the rocks by the water-fall, 
where they are exposed in large surfaces, and found them com- 
posed of basaltic trap, exhibiting in some places a distinct stratifi- 
cation, in others a confused columnar arrangement. It is also 
divided into distinct, well defined rhomboidal masses, separated from 
each other by very obvious seams, in which I frequently found cubic 
crystals of iron pyrites. Having laden myself with all the specimens 
of plants and rocks, which I had the means of carrying, I returned 
on board the Alceste, 
At day-light the following morning, 1 again visited the land, and 
directed my researches to a small island separated from Hong-kong 
by a channel not more than a hundred yards wide. It afforded 
me very few plants except the Polypodium trichotomum , but it 
presented several geological facts of much interest. This island, 
which has no name on charts, rises not more than forty feet above 
the sea, does not exceed three hundred yards in its largest, or one 
hundred in its smallest diameter, and is entirely composed of two kinds 
of rock, granite and basalt. Their junction exhibits some curious 
facts. On the north side of the island, where this is most obvious, 
it is occasioned by a dyke of basalt passing upwards through the 
granite, and spreading over it. This dyke rises from a body of basalt 
which stretches beneath the granite in a north-westerly direction, and 
vanishes beneath the surface of the sea. It is not in immediate con- 
tact with the granite, but is separated from it by three narrow veins 
