462 Notices of Memoirs — Prof. Ramsaifs Address to 



such subjects would be likely to state, for example, that in any part 

 of the globe Silurian rocks may be equivalents in time to any of our 

 Upper Palasozoic, Mesozoic, or Tertiary formations. 



For all the latest details of genera and species found in the British 

 Palgeozoic rocks, from those of St. Davids, so well worked out by 

 Dr. Hicks, to the Carboniferous series inclusive, I must refer to the 

 elaborate addi-ess of Mr. Etheridge, President of the Geological 

 Society, which he delivered at the last anniversary meeting of that 

 Society. It is a work of enormous labour and skill, which could 

 not have been produced by any one who had not a thorough personal 

 knowledge of all the formations of Britain and of their fossil contents. ^ 



In connection with such subjects I will not in any way deal with 

 the tempting and important subject of cosmological geology, which 

 in my opinion must go back to times far anterior to the date of the 

 deposition, as common sediments, of the very oldest known meta- 

 morphic strata. Cosmological speculations perhaps may be sound 

 enough with regard to refrigeration, and the first consolidation of 

 the crust of the earth, but all the known tangible rocky formations 

 in the world have no immediate relation to them, and in my opinion 

 the oldest Laurentian rocks were deposited long after the beginning 

 and end of lost and unknown epochs, during which stratified rocks 

 were formed by watery agents in the same way that the Laurentian 

 rocks were deposited, and in which modern formations are being 

 deposited now, and the gneissose structure of the most ancient 

 formations was the result of an action which has at intervals 

 characterized all geological time as late as the Eocene formations in 

 the Alps and elsewhere. 



The same kind of chronological reasoning is often applicable to 

 igneous rocks. It was generally the custom, manj'- years ago, to 

 recognize two kinds of igneous rocks, viz. Volcanic and Plutonic, and 

 this classification somewhat modified in details is still applicable, 

 the Plutonic consisting chiefly of granitic rocks and their allies, and 

 which, though they have often altered and thrust veins into the 

 adjoining strata, have never, as far as I know, overflowed in the 

 manner of the lavas of modern and ancient volcanoes. Indeed, as 

 far as I recollect, the first quoted examples of ancient volcanoes 

 are those of Miocene age in the districts of Auvergne, the Velais, and 

 the Eifel, and the fact that signs of ordinary volcanic phenomena 

 are found in almost all the larger groups of strata was scarcely 

 suspected. Now, however, we know them to be associated with 

 strata of all or almost all geological ages, from Lower Silurian 

 times down to the present day, if we take the whole world into 

 account. Amongst them, those of Miocene date hold a very promi- 

 nent place, greatly owing, doubtless, to the comparative perfection 

 of their forms, as, for example, those of the South of France and of 

 the Eifel. Their conical shapes, and numerous extinct craters, 

 afford testimony so plain, that he who runs may read their history. 



1 I must also, with much pleasure, advert to Prof. Prestwich's inaugural lecture 

 when installed in the Chair of Geology at Oxford in 1875, the subject of which is 

 " The Past and Future of Geology." 



