28 
Geology of Kerguelen s Land . 
by the heavy rains, which often succeed the frost and 
snow, accompanied by violent gusts of wind, rush down 
the sides of the mountains and along the ravines in 
countless impetuous torrents—forming beautiful cascades, 
wearing away the rocks, and strewing the platforms and 
valleys below with vast fragments and slopes of rich 
alluvium, the result of their decomposition. 
Quartz in beautiful crystals, forming drusy cavities in 
the trap-rocks, in Cumberland Bay, occurs in great 
abundance ; whilst zeolites predominate in the formations 
about Christmas Harbour. 
The most remarkable geological feature of the Island 
is the occurrence of fossil wood and beds of coal; and, 
what is still more extraordinary, imbedded in the trap- 
pean rocks. The wood, which for the most part is highly 
silicified, is found inclosed in the basalt; whilst the 
coal crops out in ravines, in close contact with the 
overlying porphyritic and amygdaloidal greenstone. 
Christmas Harbour .—The inlet in which the ships 
were moored during the'period the Expedition remained 
at the Island is bounded on the south side by a ridge of 
basaltic rocks, disposed in terraces and platforms, clipping 
slightly to the N.W., and surmounted by a remarkable 
mass of basalt, rising to about a thousand feet above the 
harbour. It has in some places a conglomerate struc¬ 
ture, the enclosed fragments being excessively hard and 
ponderous. 
It is beneath this rock that the fossil wood is found, 
the first fragment having been discovered when ascending 
the hill, on the day after the ships were secured in the har¬ 
bour; and, on a further search, we found it in considerable 
abundance, both imbedded in the basalt, and in the debris 
below, or scattered on the surface amongst the fragments 
of rock. 
A portion of a large tree, seven feet in circumference, 
