146 Prof. Hull — The Volcanic History of Ireland. 



tions ; thus guaranteeing to them the advantages of almost a double 

 circulation. 



Amongst the papers which have been read during the year 1873-4, 

 I may be allowed specially to mention those of Colonel Meadows 

 Taylor " On the Coal-fields of Central India," that of Dr. Mackloskie 

 " On the Fossil Wood of Lough Neagh," that by Dr. Macalister 

 " On the Charopsis Mibernicus," that by Mr, Hardman " On the 

 Occurrence of Zinc in the White Chalk of Tyrone," and by Mr. 

 Meadows *' On the Leinster Coal-field " ; and I take this opportunity 

 of acknowledging the gift to the Society of a mounted sheet of 

 " Griffith's Geological Map of Ireland," presented by our valued 

 member the Eev. Maxwell Close, P.G.S. 



In addressing you this evening, 1 have ventured to select as my 

 subject, " The Volcanic History of Ireland," but shall preface what 

 I have to say by a few preliminary remarks on the general charac- 

 ters of volcanic phenomena. 



The earthquake and volcanic history of individual countries is 

 one full of interest to the physical geologist. This history has been 

 ably written in the case of Scotland by Professor Geikie, and for 

 our own country it seems to be a subject not unsuited to the present 

 occasion. It is, perhaps, less difficult to decipher the characters in 

 which are inscribed the volcanic, than the seismic (or earthquake) 

 history of any special region ; for earthquakes, although generally, 

 are not exclusively, confined to volcanic districts, and often pass 

 over without leaving any traces of their action. The existence of 

 faults, or displacements of the strata, are not always to be relied upon 

 as indicating former earthquake action ; and owing to the rare cases 

 which have come under actual observation of the production of faults 

 and their connexion with earthquakes, we are not in a position to 

 speak dogmatically regarding their relationship. If volcanic action, 

 during any special geological period, were necessarily connected 

 with, or accompanied by, earthquake movements, and these again 

 with faults in the strata, it would be impossible to account for such 

 cases as the Carboniferous volcanic district of Limerick, in which 

 faults are comparatively rare ; or the more recent case of the north- 

 east of Ireland, where most of the lines of fracture are of later date 

 than the consolidation of the great sheets of lava themselves. In a 

 word, whether we regard the Lower Silurian volcanic region of 

 North Wales, so ably illustrated by Sedgwick and Ramsay, the west 

 of Ireland, the Carboniferous volcanic regions of the south of Ireland 

 or centre of Scotland, or the Miocene volcanic districts of the north of 

 Ireland and west of Scotland, we are equally impelled to the con- 

 clusion, that the main lines of fracture are totally unconnected with 

 the volcanic products, and belong to periods either preceding, or 

 subsequent to, those of volcanic activity. 



In attempting to determine those periods in the past history of 

 our globe in which volcanic phenomena have been prevalent, and 

 the districts in which the products of volcanic action have been 

 developed, we must guard ourselves against an error of observation 



