508 Notices of Memoirs — Dr. Johnston-Lavis on Vesuvius. 



In one place the pipernoid tuif is seen in section as an exceedingly 

 obtuse V-shaped mass, having choked an old valley, and possessing 

 the following characters : The black scoria fragments are very 

 slightly, if at all, flattened, are very spongy, are of good size, and 

 form an important constituent of the deposit. From this we can 

 conclude that the distance would well correspond with my supposed 

 eruptive mouth to the S.S.W. of Camaldoli, not very far from the 

 Lago d'Agnano, from which I believed issued the piperno and the 

 greater part of the pipernoid tuff of the Campania. The distance 

 was, in fact, such as to allow time for only the lighter pieces of scoriae, 

 the equivalent to the black flackers of the piperno, to travel so far, 

 and these to be so cooled, that when they fell they were sufficiently 

 rigid to no longer be flattened out by the impact. 



This grey pipernoid tuff has here suffered much denudation, for 

 in many places it is quite removed. Towards Torre Gavetta the 

 * Museum ' breccia is well developed, being composed of very large 

 blocks of the numerous varied rocks, followed by beds of the woody 

 pumice, woody looking scorias, and scoriaceous black centred vitreous 

 trachyte fragments and pumice. Lying with very marked uncon- 

 formability upon it is a great thick bed of the compact yellow tuff, 

 either derived from Campagnone or the neighbouring cone, a slice 

 of which forms Misenum. In this section we have splendidly 

 exhibited many of the great geological records in the history of this 

 remarkable volcanic region. Each of these stages is defined from 

 those above and below it by more or less long periods, during which, 

 in some cases, very extensive denudation had taken place. At this 

 point also I am satisfied we have products of the eruptions of the 

 Procida and neighbouring centres interstratified with those of the 

 mainland, and in which in time I hope to work out the relative 

 chronology. 



The discoveries, which in so striking a manner confirm my con- 

 clusions regarding the highly complex stratigraphy of this region, 

 induced me once more to examine in detail that isolated eminence 

 upon which once stood the renowned Greek town of Cumse, founded 

 about 1000 B.C. 



Time has favoured the geologist, for here, however much the 

 archfeologist maj' grieve, it has once more exposed to human eyes 

 sections that for many centuries were hidden by buildings, but 

 which reveal the fact that those very rocks that, as geologists, we 

 look upon as very recent, had nearly 3000 years since much the 

 same charactei's as now. The pumices that form the uppermost 

 yellow tuff had then already been converted into a rock that those 

 early colonists cut out and used for the construction of their walls. 

 When we first visit Cumae, and our thoughts wander back through 

 historic time, we are impressed by the human associations with 

 this hill for such a long period ; but when we return with our eyes 

 and minds geologically cultured, the ancient Greek town sinks into 

 insignificance by the side of the physical history of the mound it 

 stood upon, when we remember that not only this mound, but the 

 whole region is post-Pliocene in age. 



