458 Notices of Memoirs — 



basalt across the uplifted Cretacous and earlier strata, the counties 

 of Antrim and Londonderry include high igneous plateaux, cut by 

 deep valleys in which the underlying rocks are seen. The land- 

 scapes close around Belfast reveal the structure of the country in 

 perfection. In the west of Ireland, dykes of basalt, running 

 characteristically north-west and south-east, are so frequent as to 

 show that the plateaux once prevailed from Down to the Atlantic 

 coast. Sporadic eruptions occurred even in the Galway area, and 

 basalt fragments prevail on the sea-floor between Ireland and 

 Kockall. The granite of the Mourne Mountains was intruded in 

 the same period of unrest, and the pinnacles and rocky walls of the 

 group are a sign of youth when compared with the older granite 

 areas in Ireland. 



The existing surface of northern Ireland was determined by the 

 falling-in and dislocation of the volcanic country that once spread 

 northward to the Faroe Isles. Lough Neagh thus lies in a shallow 

 basin formed during this epoch of subsidence and decay. The long 

 sea-inlets of the north and west, including Belfast Lough and the 

 ' rias ' and ' fjords ' of Connemara and Kerry, originated about the 

 same time ; but Ireland, now cut off from the lost continent on 

 the north-west, became joined on to the growing continent of 

 Cainozoic Europe. The spread of ice in glacial times is marked by 

 numerous hills of gravel and eskers, especially in the central plain, 

 where they form green ridges rising from the bogland and the 

 prairie. The oscillations of level between the glacial epoch and the 

 present day finally left Ireland cut off from Scotland, Wales, and 

 England, with which her fundamental geological structure so 

 obviously connects her. It is interesting to note that the most 

 prominent features of her landscapes at the present day depend on 

 structures impressed upon the area far back in Palaeozoic times. 



iToariGiBS OIF nvcEiMiois-s, iejto. 



I. — British Association for the Advancement of Science. 

 Belfast, September 11th, 1902. 



Address to the Geological Section, by Lieut. -General Chas. Alexander 

 McMahon, F.E.S., F.G.S., President of the Section. 



Bock Metamorphism. 



AFTEE some prefatory remarks, the President said a brief 

 description of a granite in the Satlej Valley of the Himalayas 

 will, I think, introduce us by a short cut to the question of 

 " contact metamorphism," an important branch of the subject under 

 consideration. The granite I allude to is an intruder in the normal 

 gneissose-granite of the Himalayas, and cuts through it at right 

 angles to its foliation. The intruder, which is some yards wide, did 

 not rise through a simple crack or fissure, for its passage upwards 

 was interrupted by a sheet of dark intrusive diorite, older than 

 itself, which ran, roughly speaking, parallel to the foliation of 

 the gneissose-granite. This sheet of diorite ofiered considerable 



