1887-1888.] 51 



petrified ocean." Having pictured the character of the surface 

 upon which these flows were erupted in Antrim and in Scotland, 

 the author proceeds to describe the beds themselves, dwelling 

 at considerable length upon the immense time necessary for 

 their accumulation. Regarding their age . . . "they have 

 been regarded as of Miocene age for many years, but nothing 

 in the progress of geology has been more surprising than the 

 way in which this belief has become rooted, when we consider 

 the kind of evidence upon which it is based. Of the many 

 writers accustomed to refer to the age of the Traps as one of 

 the ascertained landmarks in geology scarcely any troubled to 

 investigate it. I have detailed it, however, in the pages of the 

 Quarterly Journal of the Geological Society for last May, and 

 we trust the question is in a fair way of being set at rest. 

 Within 100 feet of the base of the basalts in Mull occurs the 

 Ardtun flora, a rich assemblage oi plants, not one of which is 

 known in any European rocks of Miocene age. By known 

 Miocene age, I mean whose age has been determined on other 

 data than plants. They even bear no resemblance whatever to 

 such, but they do bear a resemblance to those of Sezame, 

 believed to be the oldest Eocene plants in France. Next in 

 age seems to come the Glenarm and Ballypallady beds, with a 

 peculiar group of nettles known when fossil as Maclintockii. 

 Now this group has only been met with fossil in one bed of 

 known age — the Heersian — a formation of Thanet, or oldest 

 English Eocene age, bearing the same relation to the Sezame 

 flora, as that of Ardtun does to that of Glenarm. Lastly, the 

 Lough Neagh beds have yielded plants about which I would 

 like to say something if time permitted ; though the only 

 plants I have yet determined from it are of middle or lower 

 Eocene species, but we cannot yet make out their relation to 

 the traps. We agree, however, that it is much newer than the 

 horizon at Glenarm, and it might provisionally be placed as 

 high up as the Oligocene. The origin of these vast lava flows 

 is an interesting problem. I myself firmly believe they are due 

 to what are called fissure eruptions, and that the lavas welled 

 up through long cracks, or parallel series of cracks, running in 

 the same direction as the axis of the formations." 



