1883-1884.] 271 



assigns the lowest division of the basalts to the " latter part of 

 the Eocene." " At any rate such is its contrast to the over- 

 lying sheets of basalt and amygdaloid of known Miocene age, 

 that I am constrained to infer a considerable lapse of time 

 between their respective eruptions."* All other writers speak 

 in an equally definite way of its age. No British professional 

 geologist seems to know or care anything about plants newer 

 than the Carboniferous, yet everything our foreign contem- 

 poraries have said about them has been accepted without 

 question. 



I fear I have wandered rather far afield, and spent so much 

 time in pointing out what we do not know, that little space is 

 left for what we do know. Before returning to the County 

 Antrim, it may be useful to recapitulate the chief points we have 

 noticed. 



We have first seen that the evidence of fossil plants in 

 determining the ages of late Cretaceous or Tertiary rocks is 

 almost valueless. Next, that our plants differ from those of 

 Mull completely, and that while the former find their nearest 

 allies as a flora in the Eocene of Monte Promina, the latter are 

 of late Cretaceous or lower Eocene aspect. Both, however, are 

 very similar to Greenland fossil floras, said to be Miocene ; but 

 an examination of the question shows that the evidence and 

 balance of probability is against their being of Miocene, and in 

 favour of their Eocene age. We next reviewed the evidence 

 supporting the enormous length of time occupied by the for- 

 mation of the Basalts and their subsequent denudation, and on 

 these grounds claim the utmost possible antiquity for them, 

 consistent with stratigraphical and palaeontological evidence. 

 We turned aside to notice their extent and that of other similar 

 "fissure" eruptions, as opposed to "crater" eruptions, and then, 

 in order that our ideas as to the geological periods during which 

 it was possible for them to have been erupted might not be 

 cramped, we briefly reviewed the enormous Cretaceo-Eocene 

 deposits which in other countries fill up the almost inconceivable 



* Hull, Phys. Geol. and Geogr., Ireland, 1878, cap. ili., p. 79. 



