BASALTES. 
571 
six about one, which serves as their common cen- 
tre. One half of this rock is composed of per- 
pendicular columns ; the other of another species 
of basaltes, disposed in inclined, and almost recti- 
linear, layers. These are in contact with the co- 
lumns, and are as closely connected with them as 
they are with each other : it must likewise be re- 
marked, that the layers are longer at the base than 
towards the top of the rock, and that the}^ subdivide 
in general as they rise upwards ; so that towards 
the upper extremities a layer will often exhibit 
one, two, and sometimes three divisions. These 
layers, though inclined towards the base, become 
almost perpendicular near the top of the rock, where 
they seem united in a point, and over-top most of 
the visible and elevated parts of the prismatic co- 
lumns. 
The columns terminate in such a manner as to 
form a kind of staircase. The extraneous matter 
with which these columns are covered, and of 
which the summit of this pyramid consists, ap- 
pears to be of the same species with that which 
composes the upper part of the island. The ba- 
saltes in this place are noticed to be full of small 
crystals of about the size of peas, which appear as 
beautiful as rock crystal, but are much softer, and 
yield to the action of the air. Many fragments 
of the decayed pillars which formerly contained 
crystals, are now so full of holes as to resemble a 
sponge. 
Basalt is occasionally found in a flat or round 
