30 
Geology of Kerguelen s Land. 
in length from north to south, and contracted in the centre 
to 6, occupies the depression at the summit, round 
which a pile of fragments of prismatic basalt arise on 
the east and west to about 50 feet, sloping towards the 
north and south, where gaps are left. Perfect basaltic 
columns, some of them 10 and 12 feet between the joints 
—being generally 5 or 6-angled prisms—are inclined 
round the acclivity of the cone, intermixed with piles of 
broken fragments exhibiting the same prismatic struc¬ 
ture. 
At a steep gorge, six feet wide, on the north side of 
the mountain, these columns are beautifully arranged. 
The narrow isthmus between the head of Christmas 
Harbour and the north-west coast, scarcely a mile across, 
consists of low ridges, with intervening swampy ground, 
and two lakes. The rocks are amygdaloid with super¬ 
incumbent basalt. 
Cumberland Bay . The North-west Coast , fyc .—The 
primary objects of the two expeditions up this bay in 
boats having been to explore the north-west, or weather 
shore, by an overland journey across the isthmus at the 
head of Cumberland Bay ; the rapid movements of the 
party, amidst the most unfavourable weather, seldom af¬ 
forded an opportunity for more than general remarks on 
the geological structure of the country passed through. 
On leaving Christmas Harbour, two bays were passed 
—Foul-haven and Mussel Bay: the headland dividing 
these presents a perpendicular escarpment of basalt. 
Approaching Cape Cumberland, the sea breaks upon a 
low black ledge of basalt, backed by a swampy green bog, 
two miles in length and half a mile in breadth, beyond 
which a range of trap hills arise. 
A remarkable rock, called the “ Sentry Box,” faces 
the entrance to Cumberland Bay : it was not landed 
