266 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Dec. 13, 



late Professor Pilla* has recently given a section across the gulf of 

 La Spezia, with the main points of which I entirely agree, particularly 

 in proving, that the ammonitiferous band is not the oldest limestone 

 of the tract, as was formerly supposed, hut, on the contrary, is the 

 youngest of its Jura deposits. In any attempt to classify the Jurassic 

 rocks of Ital}^, it must be admitted, that they differ so much fiom the 

 types of Northern Europe, whether in the composition of the rocks or 

 in the paucity and peculiarity of their fossils, that English geologists 

 will agree with me in thinking, that it is even more unwise than in 

 the Alps to endeavour to force their divisions into too close an accord- 

 ance with our well-kno\\Ti and clearly- characterized British formations. 

 The true doctrine on this point has, indeed, been clearly laid down by 

 Von Buch in a masterly generalization, in which, dwelhng on certain 

 marked fossils only, which pervade the Alps, Carpathians and Italy, 

 he has signalized the existence of two great bands, the lower of which 

 may be termed Jura-liassic ; the other and overlying mass, the equiva- 

 lent of the Oxford oolite and clay. I have already indicated in a 

 general manner how this classification is applicable to the Alps, and I 

 have now only to add, that though it has been as yet much less clearly 

 developed in Italy, there are sufficient evidences of its value among 

 the undulations of the Apennines and their flanking parallel ridges. 

 Jurassic formations in the gulf of La Spezia, in the adjoining ynoun- 

 tains of the Apuan Alps, and in the Monti Pisani, ^c. — The pro- 

 montories which flank the long and deep bay of La Spezia on the 

 E. andW. are composed of limestones, which, trending from N.N.W. 

 to S.S.E., are parallel to the loftier ridges of the same age, which 

 further in the interior and to the south constitute the serrated chain 

 of Carrara, Massa and Serravezza, and are, after a short interval, re- 

 produced in the Pisan hills. After looking at the latter I walked 

 over the Apuan Alps, passing from Gallicano in the valley of the 

 Serchio on the east, by the peaks of Le Pannie and the pass of Pe- 

 trosciano to Stazzemma and Serravezza ; and then flanking the western 

 zone of these Alps by Massa and Carrara to Sarzana, I traversed to 

 La Spezia. If I had seen the calcareous masses in the Apuan Alps 

 only as they there appear in the form of dolomites, rauch-kalk, and 

 many varieties of ornamental and statuary marble, I should have been 

 wholly unprepared to admit that they could be the equivalents of the 

 liassic and Jurassic series. But I satisfied myself that all these cry- 

 stalline rocks, even where they rise into the lofty peaks of Altissimo, 

 are simply altered masses, which in their prolongation to the Pisan 

 hills contain fossils. Among the lowest strata are crystalline schists 

 and pebbly conglomerate or verrucano. The geological equivalent of 

 this conglomerate has been much discussed ; some geologists, like 

 M. Pilla, desiring to prove it to be paleeozoic ; others, like Pareto as 

 before said, believing it to represent the trias ; and others, including 

 CoUegno, viewing it simply as the base of the lias. In the mean- 



* Unhappily cut off in the flower of his age at Mantua, in the late war in the 

 north of Italy. I had not the advantage of being acquainted with the memoir 

 of Professor Pilla when 1 examined La Spezia, but I was aware of his views in 

 general, as also of those of M. Collegno, who communicated a description of the 

 tract to the meeting of the Italian men of science at Venice, in which he specially 

 adverted to a great longitudinal fault. 



