J. W. Judcl — On Volcanos. 13 



varieties of character. It is interesting to notice that, while we 

 have no proof from included shells or other marine remains of any 

 part of these tuffs having been accumulated under the sea, but, on 

 the contrary, find the clearest evidence, in the leaves and stems of 

 terrestrial plants which they so abundantly yield, that a part at 

 least of them were accumulated under sub-aerial conditions, yet 

 they almost always exhibit some signs of stratification, and not un- 

 frequently, indeed, are very finely laminated. In explanation of 

 this circumstance, however, it is only necessary to point to the 

 materials, certainly of sub-aerial origin, which cover Pompeii, and 

 to the ashes ejected from Vesuvius in 1872 and still enveloping 

 its cone, both of which exhibit an unmistakably stratified or lami- 

 nated character. The remembrance of these facts may serve to 

 prevent us from too hastily inferring the sub-aqueous origin of 

 volcanic tuffs occurring among ancient geological deposits, from 

 their stratified appearance. Of beautiful examples of false-bedding, 

 unconformable stratification, and similar appearances due to the 

 action of local causes, innumerable interesting examples might be 

 adduced from among the deposits of fragmentary volcanic materials 

 in the Liparis. 



In respect to their structure, these accuumlations sometimes present 

 the character of agglomerates made up of angular blocks, including 

 some of vast dimensions, of all the varieties of lava before mentioned, 

 mingled with volcanic bombs, scoriee, lapilli, and ashes. At other 

 times they are composed of materials of more uniform character and 

 constitute tuffs ; while not rarely they are made up of fine volcanic 

 sand or dust and form beds of ash. These latter are usually of 

 a chocolate brown colour, and often contain white specks, which are 

 probably decomposed fragments of felspar crystals. 



Near Bagno Secco, on the western side of the Island of Lipari, 

 beds of rather fine-grained tuff or coarse ash are found, between the 

 laminse of which beautifully preserved leaves and stems of plants 

 occur, in much the same manner as at Somma. 



To the student of British geology the analogy presented by these 

 modern leaf-bearing tuffs with those of Miocene age at Ballypalidy 

 in Antrim, and at Ardtun in Mull, not only in the characters of their 

 materials and in the state of preservation of the fossils, but in the 

 particular groups of plants represented in them, such as planes, pop- 

 lars, willows, flags, sedges, and horse-tails, is very striking. The best 

 preserved examples of the beautiful fossil plants of Lipari were for- 

 merly obtained at an almost inaccessible point of the cliff near Passo 

 della Scarpa ; but the adventurous Liparote, who used to obtain them, 

 having lost his life in one of his attempts to reach the spot, it is now 

 rather difficult to obtain good specimens. Fragments of stems and 

 leaves, however, abound at several points, and can be procured with- 

 out difficulty by any moderately good climber. 



The tuffs, etc., of the second period of volcanic activity in the 

 Lipari Islands have suffered, equally with the lavas which accompany 

 them, from being traversed by acid gases and vapours. The action 

 of sulphurous acid on the lime of these volcanic rocks has given rise 



