494 Dr. Du Riche Preller—Ophiolithice Rocks, EL. Liguria. 
It was urged at one time as a remarkable phenomenon that in 
Eastern Liguria serpentine always appears superposed on euphodite and 
diabase, whereas in other parts of Italy, e.g. in Tuscany, the reverse 
is the case.’ The former phenomenon is, however, apparent rather 
than real, being due not only to the effects of erosion which sometimes. 
expose the outcrops at abnormal levels, but more especially to faults and 
inverted folds in connexion with the greatly disturbed stratigraphical 
condition of the whole region. Of this condition a striking example 
is afforded in the very centre of the area by Monte Treggin (870 m.), 
a sharply pointed, rugged peak, which is not only surrounded by 
chaotic masses of breccia and rock-débris, but is itself a confused 
agglomeration of the ophiolithic and sedimentary rocks of the area, 
strangely brecciated, crushed, intermixed, and contorted. This — 
phenomenally disturbed condition extends from Mte. Treggin north 
to the serpentine mass of Mte. Bocco (1,027 m.), and south to the 
ophiolithic masses near Bargone and Mte. Loreto across the Bargonasco 
and Petronia Valleys; it constitutes, in fact, an eminently cataclastic 
zone which runs north to south midway of the area and also from 
La Baracca along the western margin of the Levanto group down to 
the coast near Bonassola. 
III. Tar Monte Penna Grove. (Figs. 1 and 7.) 
This extensive ophiolithic area, the most northern of the three 
groups, lies north of Chiavari, whence Monte Penna, the highest 
point of the Ligurian Apennines (1,735 m.), forms a conspicuous 
object, distant about 25 kilometres. The group comprises a series of 
mountains disposed, on the crest of the Apennines, in a semicircle 
facing west and about 15 kilometres in length. In the centre of this 
semicircle, at 550 metres altitude, or nearly 1,200 metres below the 
crest, lies the village of Prato, one of a cluster of hamlets called 
Sopra la Croce, which possesses a mineral spring. About 900 metres 
above Prato, on Prato Molle, rises the Penna torrent, which, together 
with its numerous affluents, collects the drainage of the southern 
watershed of the Monte Penna group and discharges into the Sturla 
torrent at Borzonasca (160 m.). This village, about 15 kilometres 
from Chiavari, is the starting-point for the western and central part 
of the group, while the eastern part and Mte. Penna itself are also 
reached from 8. Maria del Taro (700m.). From west to east the 
group comprises Mte. Ajona, Cantomoro, Nero, Penna, Scaletta, 
Rocchetta, Pertusio, and Ghiffi, with the western lower spurs of 
Mte. Agugiaia, Campo Rondio, Mte. Bregaceto, and Mte. delle Lame, 
while Rocca Borzone forms a spur at the eastern extremity. 
The ophiolithic rocks, chiefly composed of peridotite, lherzolite, 
serpentine, diabase, and their breccia, are, like those of the Levanto 
and Monte Bianco groups, infolded in Eocene argillaceous schists, 
limestone, and sandstone, and follow, with the latter, the same general 
direction north to south, dipping west, although the folds and alterna- 
tions of both series are often so brecciated as to defy delimination. 
Between Borzonasca and Prato the sedimentary strata give place in 
1 See an earlier memoir by L. Mazzuoli & A. Issel, ‘‘ Studi sulle masse 
ofiolitiche della Riviera di Levante’’: ibid., 1881, p. 313 et seq. 
