THE 
GEOLOGICAL MAGAZINE. 
NEW SEBRIES@* DECADE: IH’ VOEM Vir 
No. XII.—DECEMBER, 1889. 
On Sve SEIN IaIb) WSL ICG Ibs 
— 
T.—Nortrs on THE Ponza IsnLANDs. 
By H. J. Jounston-Lavis, M.D., B.-és-Se., F.G.S., ete. 
[ 1884 I spent about a fortnight investigating the geological 
structure of these islands, and intended to have to a certain 
_ extent completed my studies at that time. Cholera was then raging 
at Campobasso on the mainland, and the islanders, not comprehending 
the curious habits of a travelling geologist, supposed I had been sent 
by the Government to spread the “‘ Cholera Powder,” and requested 
me to leave the islands by the next steamer. This I naturally for 
safety’s sake did, and opportunities for returning to the locality not 
having again presented themselves to me, and lest I should forget 
some of the interesting observations I then made, I think it desirable 
without further delay to record what I then saw. This is all the 
more important since my own observations differ considerably from 
those of the few other observers of the geology of these islands, or 
include facts which they do not mention in their writings. 
Santo Stefano is of exceeding interest from the very clear sections 
which its steep cliffs near the Cemetery present. The following 
are the details of the section : 
M. 
(2) Breccia with vegetable soil and modern pottery together with made 
earth Be 1°50 
(2) Compact brown tufa with weathered pumice, probably an old vegetable 
soil 1:30 
(ec) Ditto, but not compact and ‘containing concretions, especially at bottom, 
where it is a little more sandy . 1-10 
(Z) Two or three pumice-beds with intermediate ash-beds irregularly inter- 
bedded and concretionary along fissures He 606 coo BAO 
(¢) Dust-bed somewhat irregularly reposing on pumice-bed _ naa ... 0°50 
(f) Pumice-bed, the lower partis about m.0:10... .. 0°65 
(g) Black sand or lapillo bed ee stratified ; coarser as it ‘graduates down 
to next... S00 200 on 500 ot sete .. 0°55 
(z) Pumice and pumiceous scoria ast 306 ae w» 0°55 
(2) Earth buff fine-bedded pumice, with lapilli Bi athe aus ae ... 0°30 
(7) Loose pumice and lapilli_ ... . 0:90 
(4) Very fine buff dust, finely stratified, containing ‘bits of pumice and is 
also concretionary 1-00 
(7) Slightly concretionary dust- “bed, yellow at top, purple-brown at bottom 
and graduating thence into fine stratified dust ; the yellow bed is an 
old vegetable soil with concretions that have formed around roots and 
fills in the eroded surface of the purple-brown bed, Oiehowing weathering 
had occurred at the surface... oe p06 a8 deputies 
(m) Fine lapilli with Speen bands... nae 00 ode aOR 
(x) Pumice-bed . : yen wes Ea, Sets ses hs sco ON 
(0) Fine black scoria ... aes 500 «= O°14 
3 .. 0°28 
(y) Fine greenish-grey dust with band of lapilli at bottom ... 
DECADE Ill.—VOL. VI.—NO. XII. 34 
