Jounston-Lavis—The Eruption of Vesuvius in April, 1906. 167 
cause of disasters that further knowledge may help to prevent—catastrophes that 
there is every likelihood will occur in future. 
Sections of the fragmentary ejecta deposits around the north and east of 
Monte Somma, on the main road, upon which are situated the principal towns, 
are drawn to scale in the diagram, fig. 39. The following were the materials met 
with, which I give first at their maximum accumulation at Ottajano, extending 
eastward and south, and then follow with two to the west of Ottajano :— 
[The figures in the following sections represent depth in metres. ] 
(See Plates XX. and XXI.) 
Orrasano town. Middle of the Piazza S. Francesco. (Plate XX.) 
(a) 0°05m. of small brownish-black scoria-lapilli, almost wholly essential 
ejecta. 
(6) 015m. of larger black scoria-lapilli essential ejecta, with a red band at 
junction with last (accessory ejecta). 
(c) 0°49 m. of red lapilli, coarser at the bottom. 
Most of this is made up of fragments of ancient lavas and scorias, 
that composed the old cone-top, and therefore mostly accessory ejecta. 
Scattered sparsely are a few dense scoria fragments, some of which, 
no doubt, are essential ejecta; but their resemblance to fragments of 
accessory scoria is such as to render them indistinguishable. 
(d) 0:04 m. of grey dust, mixed with some lapilli like those beneath. 
San GIusEPPE D’ Orrasano. Olose to the station of Circum-Vesuvian Railway. 
(a) 0:04 m. fine, brownish-black scoria-lapilli, almost wholly essential ejecta. 
(6) 0:08 m. coarse, black scoria-lapilli of essentzal ejecta. 
(c') 0:17 m. brown to red lapilli, with ejected blocks of altered lava, mostly 
accessory ejecta. 
(c’) 0:08 m. red and brown lapilli in bands of different coarseness, chiefly 
accessory ejecta. 
(e*) 0:08 m. coarser lapilli, passing up into finer, also chiefly accessory ejecta. 
(c*) 0:02 m. much smaller lapilli of same kind. 
(d) 0:04 m. greyish dust. 
Casiui1. North and towards Ottajano. 
(a) 0:04 m. fine brownish-black scoria-lapilli, almost wholly essential ejecta. 
(6) 0:08 m. coarse, black scoria-lapilli of essential ejecta. 
(c) 0°39 m. red and brown lapilli of different coarseness, chiefly accessory ejecta. 
(d) 0:035 m. of greyish dust. 
