ADDRESS. 7 



This ends my list, for I have never seen, or heard, of metamorphic 

 rocks of later date than those that belong to the Eocene series. Enough, 

 however, has been said to prove, that from the Laurentian epoch onward, 

 the phenomenon of extreme metamorphism of strata has been of frequent 

 recurrence all through Paleozoic and Mesozoic times, and extends even 

 to a part of the Eocene series equivalent to the soft unaltered strata of 

 the formations of the London and Paris basins, which excepting for their 

 fossil contents, and sometimes highly inclined positions, look as if they 

 had only been recently deposited. 



Volcanoes. 



The oldest volcanic products of which I have personal knowledge are of 

 Lower Silurian age. These in North Wales consist of two distinct series, 

 the oldest of which, chiefly formed of felspathic lavas and volcanic ashes, 

 lie in and near the base of the Llandeilo beds, and the second, after a long 

 interval of repose, were ejected and intermingled with the strata forming 

 the middle part of the Bala beds. The Lower Silurian rocks of Mont- 

 gomeryshire, Shropshire, Radnorshire, Pembrokeshire, Cumberland and 

 Westmoreland are to a great extent also the result of volcanic eruptions, 

 and the same kinds of volcanic rocks occur in the Lower Silurian strata of 

 Ireland. I know of no true volcanic rocks in the Upper Silurian series. 



In the old Red Sandstone of Scotland lavas and volcanic ashes are of 

 frequent occurrence, interstratified with the ordinary lacustrine sedimen- 

 tary strata. Volcanic rocks are also intercalated among the Devonian 

 strata of Devonshire. I know of none in America or on the Continent of 

 Europe. 



In Scotland volcanic products are common throughout nearly the 

 whole of the Carboniferous sub- formations, and they are found also asso- 

 ciated with Permian strata. 



I now come to the Mesozoic or Secondary epochs. Of Jurassic age 

 (Lias and Oolites), it is stated by Lyell with some doubt, that true 

 volcanic products occur in the Morea and also in the Apennines, and it 

 seems probable, as stated by Medlicott and Blanford, that the Rajmahal 

 traps may also be of Jurassic age. 



In the Cordillera of South America, Darwin has described a great 

 series of volcanic rocks intercalated among the Cretaceo-oolitic strata 

 that forms go much of the chain ; and the same author in his ' Geological 

 Observations in South America,' states that the Cordillera has been, 

 probably with some quiescent periods, a source of volcanic matter from 

 an epoch anterior to his Cretaceo-oolitic formation to the present day. 

 In the Deccan volcanic traps rest on Cretaceous beds, and are overlaid 

 by Nummulitic strata, and according to Medlicott and Blanford, these 

 were poured out in the interval between Middle Cretaceous and Lower 

 Eocene times. 



In Europe the only instance I know of a volcano of Eocene age is 



