Here, Oliver, lad, look at the great pieces of scoria and pumice.
The scoria is let off occasionally, through holes made for the purpose.
Rabbits burrow in the heaps of scoria on the slopes of the mountains.
The telescope reveals a parapet of scoria on the brim, as on Teneriffe.
On approaching nearer the apex, the path was over cinders, fine black sand, and scoria.