452 Dr. Du Riche Preller—Ophiolathic Rocks, W. Liguria. 
crystalline massif of Savona, the pietri verdi, which overlie the 
latter at Corona, present the usual varieties already mentioned. 
Although the Triassic pietre verdi of the Voltri group and the 
Eocene ophiolithic series are both of eruptive origin, they exhibit 
certain differences, not of substance, but of facies and degree. ‘Thus, 
the older serpentines are more uniformly dark and dull in colour, the 
younger generally a brighter, richer, and more lustrous green, with 
varicoloured passages; again, the pietre verdi when schistose often 
pass to the infolding cale-schists, whilst the Hocene rocks are more 
clearly defined from the sedimentary strata. The former are more 
often amphibolic, the latter more pyroxenic, viz. diabasic. The 
serpentino-calcareous rock ‘ophicalce’ is rare in the Voltri group, 
but not infrequent in the Kocene series, and the same difference 
applies in an enhanced degree to metalliferous deposits. These 
differences are clearly exhibited in the Hocene ophiolithic series of 
Eastern Liguria, as well as in the smaller, essentially serpentinous 
and diabasic masses infolded in the Eocene sedimentary strata between 
Sestri and Isoverde and bordering on the eastern margin of the Voltri 
group. Among these are notably the outcrops of the 8. Andrea 
headland on the coast near Sestri; of S. Rocco, east of Panigara 
in the Chiaravagna Valley ; of Borzoli and of Madonna della Guardia 
at the northern end of that mass;' again, further north, those of 
Caffarella and S. Martino, which latter village is built on Kocene 
serpentine; and lastly, the Eocene serpentine with calcite veins 
known as ‘‘ verde di Polcevera”’ of Pietra Lavarezza, just below the 
Bocchetta Pass, which vies with the similar rock of Levanto in 
Eastern Liguria.?, Beyond the Pass Eocene serpentine and diabasic 
rocks appear in the Lemmo Valley near Molino di Voltaggio along 
the Bocchetta road and in the lower part of the Acquastriata ravine, 
whose upper part lies, however, in calc-schist and pietre verdi. 
Some further small masses near Voltaggio complete the Eocene 
fringe. 
As regards the anomalous position of the Voltri group east of the 
Savona massif, there is an obvious correlation between it and the 
underlying dolomitic limestone, the isolated outcrops of which all 
round the group can only be remnants of a much more extensive and 
continuous formation which reached west to the Savona massif and 
the Maritime Alps. That formation must have been overlain by 
a similarly extensive one of calc-schists and pietre verdi; hence, 
in the intervening gap in the Savona region the two formations must 
either have been removed by erosion and denudation or they must 
have been pushed over from the Maritime Alps. The gap in the 
1 Near Borzoli occurs the amygdaloidal caleareous diabase called borzolite, 
and west of Murta the cavernous variety called coschinolite by Issel. Madonna 
della Guardia is almost entirely built on diabase. 
2 The serpentine of Pietra Lavarezza with associated ophicalce is overlain by 
diabase which forms the left bank of the upper Riasse torrent. In the Recreusi 
glen, where the unconformable contact of the Triassic limestone and the over- 
lying Eocene argillaceous schist is conspicuously exposed, occur, along the 
junction of the Hocene ophiolithic rocks, large masses of Triassic gypsum 
which are quarried near Isoverde. 
