Dr. Du Riche Preller—Ophiolithic Rocks, E. Liguria. 489 
IJ.—Tue Opniortitaic Grovurs oF rHE LicuRIAN APENNINES. 
Il. Easrern Liguria. 
By C. S. Du RICHE PRELLER, M.A., Ph.D., M.I.H.E., F.G.S., F.R.S.E. 
GENERAL FEATURES. 
fJ\HE three principal ophiolithic groups of this region are those of 
Levanto, Monte Bianco, and Monte Penna, about midway 
between Spezia and Genoa, viz. north of Levanto, Sestri Levante, 
and Chiavari, at average altitudes of 300, 800, and 1,600 metres 
respectively. Like the Eocene ophiolithic group of Sestri Ponente 
and Isoverde, west of Genoa, they lie in the upper horizon of that 
formation, that is, in the fossiliferous (fucoids) albarese limestones 
and the argillaceous schists which rest on the Middle Eocene macigno 
sandstone as the lowest member of the Ligurian Eocene. The 
sedimentary and infolded ophiolithic groups consecutively aligned 
from the coast to the crest of the Apennines form a series of anti- 
clines north to south, dipping west, with some transverse folds. The 
whole region is greatly contorted and brecciated; it is, moreover, 
profoundly eroded by torrents charged with calcium carbonate which 
has accelerated erosion and at the same time re-cemented breccia. 
Although the three groups are now separated, they are, together 
with the scattered islands north of the crest of the Apennines 
towards Piacenza in the Po Valley, only the remnants ofan originally 
continuous formation of no less than 1,500 square kilometres or 
600 square miles. 
The principal ophiolithic rocks of the three groups are serpentine, 
euphodite, and diabase, with their varieties. The serpentine is both 
compact and schistose, and often of porphyric structure. There is no 
passage from serpentine to the other two rocks, but there are frequent 
transitions between the latter; serpentinous schist or pseudo- 
serpentine, often in transition to argillaceous schist, is also much in 
evidence. Associated rocks are the semi-crystalline schists known as 
flaniti and diaspri, viz. silico-caleareous, reddish and green schists, 
harder than limestone, indurated by taking up silica at the expense 
of lime, and containing radiolaria. Both, and notably the more highly 
‘indurated diaspri, form bands on the margin of ophiolithic rocks in 
proximity to calcareous masses.! It is a noteworthy feature that 
metalliferous deposits are found only in euphodite and diabase, never 
in serpentine, though often near the contact of the latter; again, 
manganese occurs, not in the ophiolithic rocks proper, but in the 
diaspri masses, though in the vicinity of the former. 
I. THe Levanto Group. (Figs. 1 and 5.) 
This extends along the coast from Monterosso to Levanto, 
Bonassola, and Framura for about 10 kilometres, and inland about 
20 kilometres to north of La Baracca on the high-road from Sestri 
Levante to Spezia. ‘The precipitous, craggy outcrops along the coast 
are composed chiefly of greenish and dark reddish serpentine and of 
1 Indurated, silico-argillaceous schists are known as galestri, yellowish, red, 
or green in colour; ardesia are tegular, silico-argillaceous-caleareous schists ; 
and resinite is a white or yellowish siliceous, semi-opaline variety. 
