THE VOLCANOES AND ROCKS OF PANTELLERIA 667 
That such a movement can have taken place on the island is 
shown by that preceding the submarine eruption of 1891 near the 
corner of the island, when a section of the northeast coast from 
Punta Karuscia to Punta Tracion was raised nearly one meter.* 
Such a tilting of a fault block explains reasonably the steep scarps, 
their presence only at one end of the mass, the revealed structure of 
sheets of columnar flows, and the general slope of the surface toward 
the north, while the simple set of two almost straight lines formed 
by the scarps is also in harmony with this interpretation. 
Subsequent to this dislocation the second stage of the second 
phase took place in the formation of the small parasitic cones of 
Fosso del Russo, Monti Gibilé a and 6, Cuddia Randazzo, Monte 
Gelfiser, and others, which poured out flows only of black pan- 
tellerite (Foerstner’s vitreous pantellerite). It is noteworthy that 
all these small cones are found on the edges of the Montagna Grande 
block, just where the movement of the block would give exit to the 
magma along the fracture lines. None of them have broken through 
the main area of the mass, though it is uncertain whether Cuddia 
Sciuvechi, which also poured out black pantellerite, is along the 
western fracture line or on the slope of the original large volcano, 
and hence belonging to Phase I. 
The southern cones of this period, Gibilé a and 6 and Russo, are 
of small size, and their flows are short and barely do more than reach 
the bottom of the old caldera flow, not getting as far as the opposite 
inner somma ring. The northern cones, on the contrary, Cuddie 
Randazzo and Gelfiser, are much larger, and their flows of much 
greater length and volume, Khagiar reaching the sea and Gelfiser 
coming up to the Zeneti scarp and apparently overflowing the 
northwest corner portion of the tilted block. It will be observed 
that this disposition is in harmony with the structural explanation 
here suggested. 
According to this interpretation the Bagno dell’ Acqua (with the 
alluvial Rione) is not a center of eruption, as supposed by Foerstner 
and Bergeat, but part of the old caldera floor, somewhat lowered by 
the block tilting, and left uncovered by the flows of Monte Gibele 
and those following the Montagna Grande dislocation. This 
1G. A. Butler, Nature, XLV (1891), 584. 
