8 EEPORT— 1880. 



that of Monte Bolca near Verona, where the volcanic products are asso- 

 ciated with the fissile limestone of that area. 



The well-preserved relics of Miocene volcanoes are prevalent over many- 

 parts of Europe, such as Auvergne and The Velay, where the volcanic 

 action began in Lower Miocene times, and was continued into the Pliocene 

 epoch. The volcanoes of the Eifel are also of the same general age, 

 together with the ancient Miocene volcanoes of Hungary. 



The volcanic rocks of the Azores, Canaries, and Madeira are of 

 Miocene age, while in Tuscany there are extinct volcanoes that began in 

 late Miocene, and lasted into times contemporaneous with the English 

 Coralline Crag. In the north of Spain also, at Olot in Catalonia, there are 

 perfect craters and cones remaining of volcanoes that began to act in 

 newer Pliocene times and continued in action to a later geological date. 

 To these I must add the great coulees of Miocene lava, so well known in 

 the Inner Hebrides, on the mainland near Oban, &c., in Antrim in the 

 north of Ireland, in the Faroe Islands, Greenland, and Franz-Joseph 

 Land. It is needless, and would be tiresome, farther to multiply instances, 

 for enough has been said to show that in nearly all geological ages 

 volcanoes have played an important part, now in one region, now in another, 

 from very early Palaeozoic times down to the present day ; and, as far as 

 my knowledge extends, at no period of geological history is there any sign 

 of their having played a more important part than they do in the epoch 

 in which we live. 



Mountain Chains. 



The mountain- chains of the world are of different geological ages, 

 some of them of great antiquity, and some of them comparatively 

 modern. 



It is well known that in North America the Lower Silurian rocks lie 

 uncomformably on the Laurentian strata, and also that the latter had 

 undergone a thorough metamorphism and been thrown into great anti- 

 clinal and synclinal folds, accompanied by intense minor convolutions, 

 before the deposition of the oldest Silurian formation, that of the Potsdam 

 Sandstone. Disturbances of the nature alluded to imply beyond a doubt 

 that the Laurentian rocks formed a mountain chain of pre- Silurian date, 

 which has since constantly been worn away and degraded by sub-aerial 

 denudation. 



In Shropshire, and in parts of North Wales, and in Cumberland and 

 "Westmoreland, the Lower Silurian rocks by upheaval formed hilly land 

 before the beginnmg of the Upper Silurian epoch ; and it is probable that 

 the Lower Silurian gneiss of Scotland formed mountains at the same 

 time, probably very much higher than now. However that may be, it is 

 certain, that these mountains formed high land before and during the 

 deposition of the Old Red Sandstone, and the upheaval of the great 

 Scandinavian chain (of which the Highlands may be said to form an out- 



