1897] 55 



SOME NEW BOOKS 



Oui; Dead Volcanoes 



The Ancient Volcanoes of Great Britain. By Sir Archibald Geikie, F.R.S. 8vo. 

 2 vols., pp. xxiv. and 478, and pp. xvi. and 492. With 7 folding maps and 383 

 illustrations. London : Maemillan & Co., 1897. Price, 36s net. 



This work is an expansion of the two addresses given by its author to 

 the Geological Society of London in 1891 and 1892. Those of us who 

 have often marvelled at the amount of detail, largely new, that was 

 brought into the compass of the addresses, may have foreseen the solid 

 and permanent character of the two large volumes now before us. 

 In earlier years, Sir Archibald Geikie spent his leisure in volcanic 

 areas — travelling, observing, correlating, and storing up the wealth of 

 information which is now made orderly and accessible. The 270 

 pages — more than a quarter of the whole work — devoted to the 

 Devonian, Carboniferous, and Permian volcanoes of Scotland will be 

 welcomed on these historic grounds. And in later years, with the 

 resources of the Geological Survey at his command, the author has 

 been able to extend his area, so as to examine the whole range of vol- 

 canic phenomena in our islands. Ireland is not mentioned in the 

 strict title of the work, but is in reality dealt with in a manner that 

 atones for a great many omissions on the part of British text-books. 

 We have here, in fact, a basis which must be consultedbefore work is 

 begun on any igneous rocks of the British Isles, for Sir Archibald 

 frequently, and very properly, treats of holocrystalline and deep-seated 

 masses in addition to the volcanic relics associated with them. 



So far as we can judge, the passages compiled from previous writers 

 have been drawn up with admirable accuracy, even to the use of the 

 rock -names employed in the original papers. These names, in fact, 

 would sometimes be the better for a little comment or revision, as in 

 the case of the French rock-term ' labradorite,' imported on p. 29. 

 The book is, however, written for geologists, and largely for those 

 engaged in actual investigation ; it has, at any rate, the merit of offer- 

 ing no encouragement to young persons 'reading' for examinations. 



AVhile book i. is of a general character, there is much in it that is 

 admirable and suggestive to the worker in the field. We may note, 

 for instance, the diagram of " the gradual emergence of buried volcanic 

 cones through the influence of prolonged denudation " (p. 75). The 

 characteristic structures of iy-neous rocks are described, and are illus- 

 trated by photographs from actual specimens. The polished surface 

 of ' Napoleonite ' on p. 22, and the fluidal Antrim rhyolite on p. 23, 

 are perfect examples of their kind. 



It is surely, however, an undue extension of terms to call the 

 structure of ' Napoleonite ' variolitic ;. and we could wish that vario- 

 litic and orbicular structure had not been separated from spherulitic 

 in the text. The ophitic structure, again, is referred to, as in so many 



