OF THE BASALTIC FOEMATIOX OF TJL8TEK. 83 



show that this was bordered in places by marshy or boggy land. All 

 the physical data combine to prove how vast the antiquity of this 

 part of the formation must be ; but as I have recently discussed 

 these at some length elsewhere (and those interested can follow my 

 arguments in the ' Report of the Belfast JSTaturalists' Field-Club ' 

 for the year 1884), I do not propose at present to allude to them 

 further. Conclusive, however, as the inferences deduced from phy- 

 sical data appeared, I am able, through still more recent investigations, 

 to set aside the whole of this evidence, and to demonstrate on simple 

 palseontological data that the plant-beds are actually very low down 

 in the Eocene series. All are aware how universally they have 

 hitherto been regarded as Miocene. IN'othing, indeed, in the progress 

 of geology appears more remarkable than the almost complete una- 

 nimity with which their age has been accepted, when the character 

 of the evidence is examined. Of the many distinguished writers on 

 the basalts of Ireland and Scotland, not one has called it in question ; 

 and Prof. Hull, for instance, almost apologetically ventures to speak 

 of the lowest trachyte or porphj-ry of Sandy Brae as " possibly be- 

 longing to the latter part of the Eocene series ; " " at any rate, such 

 is the contrast to the overlying sheets of basalt of known Miocene 

 age, that I am constrained to infer a considerable lapse of time 

 between their respective eruptions "*. 



As I propose to review this evidence at length elsewhere, I do not 

 think it necessary to do more than glance at it now. The first 

 description of any inter-basaltic plants was communicated to this 

 Society by Edward Eoi^bes in 1851 f. Our knowledge of Tertiary 

 plants was very meagre thirty-three years ago, and he was only able 

 to hazard the opinion that, judged by the then state of our know- 

 ledge, they were " decidedly Tertiary," and " most probably " Mio- 

 cene. Heer + subsequently claimed two of them as Miocene forms ; 

 but the first is merely a yew-like coniferous twig, probably a Taxus, 

 that might be of any age ; and the second a dicotyledonous leaf which 

 finds its parallel equally in the Cretaceous and in the old Eocene of 

 Sezanne. Many of the Mull plants are also found at Atanekerdluk ; 

 but the age of these beds has been settled in precisely the same per- 

 functory manner as in the instances we are discussing. It occurred to 

 somebody that the Antrim and the Mull plants must be of the same 

 age ; but the only notice I can find of any actual comparison of them 

 is by Baily §, whose conclusion that they differed as a group tells in 

 an entirely opposite sense. I am, in fact, personally aware, so far, 

 only of one plant in common ; and this is not only rather doubtful, 

 but was discovered at Mull only three or four years ago, and is not 

 yet published ||, nor has it been made use of by any one for 

 comparison. The Irish plants are all from below the columnar 

 basalts and are very considerably older than the Mull plants, which 



* Hull, Phys. Geol. & Geogr. Ireland, 1878, chapter iii. 



t Quart. Journ. Geol. Soc. toI. vii. (1851), p. 103. 



\ LyeU's ' Elements of Geology.' 6th edit. 1865, pp. 261, 262, 



§ Quart Journ. Geol. Soc. vol. xxv. (1869), p. 360. 



II Since published in the issue of the Palaeontographical Society for 1884. 



