432 
DRS. T. ANDERSON AND J. S. FLETT ON THE ERUPTIONS OF THE 
many ways the perlitic structure shown hy certain igneous glasses, and the siaheroidal 
stiuctiire of weathered dolerites. 
Another type of rock fairly well re})resented among the blocks imbedded in the ash 
in the'Wallihu was a granular, holo-crystalline aggregate of felspar, brown horn¬ 
blende, and olivine in very varying proportions. They appeared to he agglomera¬ 
tions of the first minerals to crystallise out of the igneous magma within the crater, 
but a minute description of these, and a discussion of their origin, may be deferred 
till they have been more completely investigated. 
The most striking feature of the Wallibu deposits was the scarcity of coarse 
material. Certainly over 90 per cent, of the whole could only be described as a 
volcanic sand, and often the fragments above a couple of inches in diameter did not 
form over 3 per cent, of the mass. These statements are based not on the appear¬ 
ance of the surface, where the coarser and heavier materials had been concentrated 
by the action of rain in washing away the finer stuff, but on the vertical sections 
afforded by the cliffs, ’^vhere the ash could be inspected in the condition in which it 
fell. There were not a few places where we found it impossible to collect any number 
of stones large enough to yield good hand specimens. Where the larger blocks and 
bombs did occur they were often numerous, forming fields of stones, and in each area 
they seemed to be, as a rule, of the same kind, as if the materials had fallen together 
like the rain of sparks from a rocket. In one place we might find a cluster of bombs, 
in another of ejected blocks, and so on, and each diffei'ent part of the area yielded 
distinct types of rock. 
The vertical sections of the new ash did not show any very distinct stratification, 
nor were the larger blocks more abundant near the lower surface. Most of the 
material was as little stratified as a recent blown sand. At the base lay the charred 
crops of sugar cane, not burnt up or destroyed, but rotting Avhere exjDosed to the 
atmosphere under the attack of sajArophytic fungi, AAdiich gave out a stench resembling 
that of guano. 
The ash itself was very hot. Probably it was not cpiite red-hot, though as we were 
never on it hy night, we cannot say how it Avould have looked in the dark. But if a 
AvalkiiiP-stick were thrust several inches into it and AvithdraAvn after a minute or two, 
the brass ferrule was too hot to handle. The surface AAdren wet AAvrs cool, firm, and 
good to walk upon, exactly resembling a fine cinder path. After showers, hoAA'ever, 
it soon dried, and the sides and bottoms of the little rain-ifflls became sufficiently hot 
to burn the naked feet of our coolie porters. From cracks in the ash, through 
wdiich water had percolated to the interior, steam constantly ascended in little jets, 
which deposited'thin yelloAv and greenish incrustations. One day, as we AA^ere being 
roAved to the lairding-place nt the mouth of the Wallibu EiA'er, a ■ landslijD took 
place in the dry, yelloAAnsh ash on the top of the Ioav sea cliff. The starmp of a tree, 
Avhich had been entoml^ed in the ash, Avas in this Avay exposed. It Avas charred but 
covered Avith a film of grey dust, and as soon as the air touched i-f, the Avood burst 
