180 HAWAIIAN ISLANDS. 
solite. We shall speak more particularly of its composition on a future 
page. It is compact, with some scattered cellules; excepting the 
crust already alluded to it is far from scoriaceous. The specimens 
usually brought from Kilauea are from this scoria, and give no idea 
of the ordinary rock of the daily ejections, as this scoria constitutes 
but a few inches out of the ten or twenty feet of which a layer may 
consist. Similar layers, piled upon one another, form the walls of the 
lower and upper pit, the rock being mostly compact, with compara- 
tively few disseminated cellules, and seldom scoriaceous. The crust 
of glassy scoria disappears after every following eruption, the new 
overflow melting the old surface, which afterwards, on cooling, be- 
comes rock, like the material above it: thus in the walls of the lower 
pit, where sections of the layers ejected during the few previous years 
are well exposed, we find only the compact lava, and no intervening — 
scoria. ‘The alternations in the walls of the lower pit show slight 
variations in shade of colour and in the proportion of chrysolite, which 
mineral is nowhere abundant. ‘The ejected lava from different sources 
in the crater has, at times, been thrust out into projecting knobs, which, 
from rapid cooling, have a glassy exterior, and are nearly as brittle as 
a Prince Rupert’s drop. 
It is an observation, which we shall show hereafter to be of much 
interest, that some of the lavas within the crater are not covered 
with a scoriaceous crust. On the contrary, while the overflowings 
of the pools or lakes are of this character, the eruptions through other 
openings have generally a solid surface, and are either solid stone 
throughout, or have a compact glassy exterior, half an inch thick. 
The walls of the upper pit we had no chance particularly to ex- 
amine in the single day’s ramble to which we were restricted. ‘The 
inadequacy of this amount of time for anything like thorough investi- 
gation into many points that demanded attention, is obvious, and 
especially if it be considered that, after making a descent into the crater 
as far as the black ledge, there was still a walk of three miles to one 
of the boiling pools at the bottom; and from the same place to the 
sulphur banks on the southeast wall of the crater, required another 
walk of six miles. 
In the preceding descriptions we have made only a bare allusion 
to the sulphur banks. Instead of being conspicuous objects about 
the crater, they might be passed by, unless under the direction of a 
guide. On the southeast side of the crater, the wall, which has 
