THE VOLCANOES AND ROCKS OF PANTELLERIA 665 
blocks, concentric about the central mass, a case which, so far as I 
know, is unparalleled elsewhere, especially on so small a scale; or 
the other as due to erosion along the fault zone, which is also 
difficult to accept in view of the relatively dry climate and the 
character of the surface-drainage topography. 
Without desiring to be polemical, I may mention that the fault- 
lines mentioned by Foerstner, and indicated on the small map by 
Bergeat, seem to me to be somewhat -arbitrary and subjective and 
their apparent parallelism rather forced by judicious choice. Thus, 
the most northeasterly connects the Bagno dell’ Acqua (which can 
scarcely be regarded as a volcanic center) with a very minor part of 
the Montagna Grande scarp. That on the southwest connects the 
very minor Cuddia Sataria with a not very pronounced part of the 
coast line. That connecting Cuddia Sciuvechi and Monte Fosso 
del Russo might have been extended on the one side to Cuddia 
Gelkhamar and on the other to Cuddia Attalora with little deviation 
from a straight line. Also, they are arbitrary in their omissions. 
Thus, radiating lines might have been drawn from Cuddia Mida as 
a center toward the north, northwest, and west, each of which would 
have run through three or more volcanic cones, and such radiating 
lines would have been consonant with the radiating system of dikes 
observed about many volcanoes. 
Author's views —Accepting the hypothetical granitic basement, 
which is in harmony with observations on Linosa, I suppose that the 
first volcano (which presumably started in submarine eruptions like 
those in 1831 and 1891") was a large one and covered the whole of 
the present area of the island, except possibly a small area at the 
northwest. The flows poured out by this volcano were of pan- 
telleritic trachyte (Foerstner’s ‘“‘phonolite” and ‘“‘later andesite’’) 
and of comendite (Foerstner’s ‘‘liparite’’), the now existent sheets 
of which formed the lower flanks of the old cone. On the west, 
at the Costa Zichidi and the Scauri district, they still show in places 
traces of the original lava surfaces. Later than these, but issuing 
from the same volcanic center, which may be supposed to have been 
probably between the Cuddia Mida and Monte Gibelé, were flows 
of green pantellerite (Foerstner’s crystalline pantellerites), which 
«Cf. H. S. Washington, Am. Jour. Sci., X XVII (1909), 131. 
