Geological Society of London. 91 



II.— Jan. 12, 1887.— Prof. Judd, F.E.S., President, in the Chair. 



The President announced the sad loss which the Society 

 had sustained since the last Meeting, by the death on 4.th 

 January of Mr. John Arthur Phillips, F.R.S., who had been 

 for several years a valuable member of the Council, and one of 

 the Yice-Presidents of the Society. 



1. " The Ardtun Leaf-beds." By J. Starkie Gardner, Esq., F.G.S., 

 F.L.S. ; with Notes by Grenville A. J. Cole, Esq., F.G.S. 



The description of these beds by the Duke of Argyll thirty-five 

 years ago indicated that enormous tracts of Trap in the Inner 

 Hebrides were of Tertiary age. Prof. Edward Forbes, who described 

 the leaves, inclined to the idea that they might be Miocene ; but in 

 estimating the value of this conjecture, we must remember that at 

 the time the existence of Dicotyledonous leaves of similar aspect, but 

 of undoubtedly Cretaceous age, was quite unsuspected, and that no 

 typical Eocene flora had then been properly investigated or described. 

 Prof. Heer, however, adopted the opinion that the age of this for- 

 mation was Miocene, and unfortunately extended its application to 

 formations containing similar floras in Greenland and elsewhere. 

 One object of the present communication is to show that, instead of 

 belonging to the Miocene, these floras are of Eocene age, and in fact 

 older than the Thanet beds. The other object is to redescribe the 

 plant-beds, and to show that they are part of a rather extensive 

 series of sedimentary rocks intercalated among the Traps. 



The rapid accumulation of knowledge as to the distinguishing 

 characteristics of Cretaceous, Eocene, and Miocene floras has rendered 

 the attainment of the former object at least possible, and it is of the 

 greater importance, since the error in determining the age of the 

 fossil floras of Ardtun and Antrim, and of a part of the Arctic flora, 

 is a great impediment to further progress. Instead of all these 

 immense thicknesses of beds belonging to the Miocene, they have 

 their base somewhere in the so-called Cretaceous series ; 400 feet 

 higher up we are about the horizon of the Thanet Beds ; while at 

 1000 feet up the flows were contemporaneous with the Bracklesham 

 and Barton deposits. The first acid eruptions were Miocene, as 

 shown by the floras preserved in Iceland. 



The author described the various exposures from his own 

 observations and Mr. Cole's notes. At Ardtun the Traps are 

 surmised to be parts of once continuous flows, still represented 

 at Staff"a and Burgh, but broken through by an intrusive sheet. The 

 leaf-beds are varied in composition, the richest being very friable, 

 while the best matrix is a limestone as fine as lithographic stone, in 

 which plant-remains are few, but exquisitely preserved. They are 

 overlain by thick deposits of river-gravel, chiefly composed of flint 

 or silicified chalk, but in which Mr. Cole has detected fragments of 

 sanidine like that of Ischia or the Ehine, and of trachyte. At Carsaig 

 the gravels are coarser and less evenly bedded, and the sandy matrix 

 apparently is entirely made up of flint. The coarse gravels are 

 flanked by sands and indicate a rapid flow of water, occupying a 



