142 AMSTERDAM ISLAND. 
two discordant elements must have sustained, when the liquid 
lava encountered the waves of the ocean. The effects of 
such a strua'O'le are still more distinctly seen on an extraordi- 
narj insulated rock of a pja-amidal form, which rises out of 
the sea a little to the right of the entrance into the crater. 
The heioht of this rock is from two to three hundred feet, and 
it is composed of forty or fifty horizontal layers piled very 
regularly on each other ; and these are again cracked and 
divided by a number of perpendicular fissures, the whole ex- 
hibitino- a hupe mass of basaltic columns. The marks of fusion 
are evident on every part of its surface, which has the appear- 
ance of scoria from an iron furnace. Man}^ of the perpendicu- 
lar fissures were filled with veins of obsidian or volcanic glass, 
which we could perceive to be extended several feet below 
the surface of the sea. In other clefts we found some curious 
specimens of zeolite, but looked for this substance in vain in 
the fraoments of solid lava. We were the more desirous of 
establishing this fact, as it is one of the contested points be- 
tween the Plutonists and the Neptunists. Zeolite being fre- 
quentl}" found in the midst of basalt, and being well known 
to contain a considerable quantity of water, has furnished 
one of the strongest ai'guments in favour of the Neptunists ; 
in so far at least as it militates against the doctrine of basaltic 
columns being produced by the agency of subterranean heat. 
Zeolite and volcanic glasses, such as obsidian and pumice 
stone, we found abundantly on every part of the coast of 
the island. 
On the two causewaj's in the breach made by the sea into 
the crater, and in many places on its slanting sides, we found 
