ON THE TOLCANIC PHENOMENA OF VESUVIUS. 325 



the presence of basic and acid rocks amongst the ejected blocks of the 

 piperno volcano. 



That the fluoriferous metamorphism of limestone in the grey tuff 

 occurs only where the allavium of the buried limestone mountains en- 

 veloped fragments of that rock. 



Artesian Borings and Sections at Pozzunli. — Nine more borings have 

 been made on the coast and in the sea at from 100m. to 150m. from 

 the temple of Serapis. Along the sea-border, historic deposits were 

 met with at from 11m. to 13'24m. in different borings; at 30m. from 

 the beach historic deposits reach 937m. ; whilst at 50m. distant, 

 in two borings they were traversed to 21m. and 22m. At 140m., 

 beneath 5m. of water, rounded bricks and pottery-fragments ex- 

 tended down to 14m. and 15"50m. respectively in two borings. Beneath 

 the historic deposits nothing but sea-sand and mud were met with ; but 

 none of the borings extended much beyond 20m. At one point hard 

 rock was struck at a small depth, and four other borings were made 

 within a few yards, all touching hard rock. It is much to be regretted 

 that none of this was detached for examination. 



Nothing of any importance is demonstrated by these deposits except 

 the very considerable deposit filled by brick, pottery, marble and other 

 fragments, and still further confirming the depression of this region. 



In cutting the new road opposite the main entrance to Sir W. 

 Armstrong, Mitchell & Co.'s Works, a raised beach of post-Roman age 

 was exhibited, with clean sand, many pebbles of bricks, marble and 

 rounded fragments of mosaic. There are masses of wall fallen from the 

 cliff-edge above as it was cut back by the sea, in which the edges, angles, 

 &c., had been much rounded by the waves. The highest point, so far as 

 this beach was exposed, occurs at 3'75m. above present mean sea-level. 



A similar condition exists against the foot of the Villa of Cicero (i.e. 

 the ruin beneath the Villa Armstrong), and west of the extremity of the 

 valley in which the new reservoir has been constructed. There this 

 beach reaches to nearly 5m. above mean sea-level. We have in these 

 two localities distinct evidence of depression of the coast having 

 reached at least 5m. lower than at present ; evidence quite independent 

 of that afforded by the temple of Serapis. At the moment that the land 

 was at its lowest, the cliff was cut back considerably, causing the old 

 Roman foundation to be exposed and in part to fall, to be broken up and 

 rounded by the sea. 



Close to the main entrance of the Armstrong: Works the shrinkinsr 

 pit has been sunk to a maximum depth of about 15m., 12 of which are 

 below sea-level. Various beds of lapillte and pumice were met with, and 

 near the bottom many ejected blocks of a peculiar trachyte, together with 

 tuffs, some of each much altered by solfataric action. Most interesting 

 was a peculiar mica-diorite (?) containing much pyrites. This rock I 

 have occasionally met with elsewhere in the region ; but it is always of rare 

 occurrence. Professor Roth, of Berlin, who examined the specimens 

 with me in situ, expressed great interest and astonishment at their occur- 

 rence. These are reserved for further study. The influx of water into 

 the excavation was interesting, that on the side of the sea being very 

 salt, whilst a cascade of warm mineral water flowed from a fissure on the 

 land side, the two keeping a 20-horse pump constantly at work. 



This report is but a slight sketch of the observations being carried on, 

 which require constant and untiring attention. Even as it is, great 



