! the Island of Tristan da Cunha, $c. . 485 
The mountain appears to have been rent asunder by some vio- 
lent convulsion, and the fissures filled up by a hard stony mass of 
a blueish or a reddish colour, and of the nature of trap, forming 
regular veins, the ramifications of which can be traced by the eye 
to a great height in the face of the rock. The sides of these veins, 
where they come in contact with the rock, are invariably in a 
semivitrified state, and exhibit obscure marks of crystallization. 
Along the north-west side of the island there runs a belt of low 
land about six miles long, varying from a quarter of a mile to a 
mile in breadth, and presenting to the sca a perpendicular front 
from fifty to three hundred feet in height. The whole of this 
plain is a confused assemblage of stony fragments, scoria, and - 
other volcanic products, resting on a bed of Java. All these mat- 
ters are in a progressive state of disintegration, and the greater 
part of them reduced to mere nuclei imbedded in their consti- 
tuent elements in the state of a black indurated earth. 
_ The northern extremity of the plain is in a great measure cleared 
of its wood. By setting fire to the grass the trees have been so far 
scorched as to destroy their vegetation ; but-they still lie strewed 
along the ground, and it will cost some labour to remove them. 
The rest is still in a state of nature, covered with an impenetrable 
copse. 
_. The surface of the plain, though apparent! y smooth and even 
while clothed with its native herbage, is in fact extremely irrega- - 
lar, being every where broken by small ridges of loose stones 
concealed under a mere scurf of soil. Between those ridges, how- 
ever, the soil is pretty deep, and consists for the most part of the 
remains of decayed vegetables, with here and there a substratum 
of alluvial earth approaching to the nature of clay, . It is soft, 
spongy, retentive of moisture, and possesses most of the charae- 
ters of peat. ‘This soil has been found admirably adapted for the 
3 R2 production 
