42 Reports and Proceedings — 



Mr. Montagu Smith; but for the loan of many specimens the 

 author is indebted to Mr. E. M. Brydone, Mr. C Griffith, Mr. \Y. 



Hill, Dr. J. Morison, and Mr. James Saunders. In addition to 

 some genera, of which sufficiently good examples for exact deter- 

 mination have not yet been obtained, the following are repre- 

 sented : Nautilus, Ptychoceras, Heteroceras, Bacidites, Prionocyclus, 

 Pachydiscus, Scaphites, Crioceras, Emarginula, Pleurotomaria, Trochus, 

 Turbo, Crepidula, Natica, Cerithium, Aporrhais, Aveilana, and 

 Ventalium. Some new species are described, and the synonymy 

 and distribution of the others treated in detail, figures and descrip- 

 tions being given of the forms not previously well known. The 

 account of the Lamellibranchs and the general conclusions are 

 reserved for Part II. 



III. -December 18, 1895.— Dr. Henry Woodward, F.R.S., Presi- 

 dent, in the Chair. The following communications were read : — 



1. "The Tertiary Basalt-plateaux of North-western Europe." By 

 Sir Archibald Geikie, D.Sc, LL.D., F.R.S. 



The author in this paper gives the results obtained by him in the 

 continued study of Tertiary Volcanic Geology in the seven years 

 which have elapsed since the publication of his memoir on ' ; The 

 History of Volcanic Action during the Tertiary Period in the British 

 Isles." His researches have embraced the western islands of 

 Scotland, St. Kilda, and the Faroe Islands. 



(1) In an account of the rocks of the basalt- plateaux attention is 

 particularly directed in this paper to a type of banded basic lavas 

 which play an important part in the structure of the volcanic dis- 

 tricts both of the Inner Hebrides and of the Faroes. The banding 

 sometimes consists in layers of more highly vesicular structure, 

 sometimes in alternations of distinctly different lithological cha- 

 racter, such as close-grained basalt and more coarsely crystalline 

 dolerite. These banded rocks are more particularly developed in 

 the lower portions of the volcanic series. At a distance they might 

 be mistaken for tuffs or other stratified deposits. They occupy 

 a conspicuous place in the great precipices of the west and north of 

 the Faroe Islands. 



Numerous examples are cited of the ending-off of basalt-sheets in 

 different directions, indicative of many local vents from which the 

 lavas issued. An account is also given of tuffs and other stratified 

 intercalations which occupy a subordinate place in the structure of 

 the plateaux. 



(2) A number of examples is given of the volcanic vents which 

 form a characteristic feature of the basalt-plateaux. A remarkable 

 row of five such vents was met with by the author at the base of 

 the great cliffs on the west side of Stromo, in the Faroe Islands. 

 They are occupied with agglomerate, and their saucer-shaped craters 

 have been filled in by successive streams of lava from neighbouring 

 vents, the whole being buried under the great pile of basalt-sheets 

 forming the island of Stromo. 



An instance of similar structure is described from Portree Bay, 



