3 6 [Proc. B.N.F.C., 



a short paper on local geology, a subject of which he is a very 

 capable exponent, having been engaged on Her Majesty's 

 geological survey. After referring generally to the basaltic 

 formations and their undoubted volcanic origin (a proposition 

 long disputed, many maintaining their origin was aqueous), he 

 described graphically a recent visit to Vesuvius, and the seething 

 lava that flowed down the sides of that mountain. Such was 

 the action which went on here over an area extending from 

 Moneymore to the Island of Mull, which was no doubt the 

 most active of all the volcanoes of a district extending over an 

 area of some 2,000 square miles, and leaving behind, after all 

 the denudation which has since taken place, including that of 

 the glacial period, a thickness of basalt of upwards of 1,000 feet 

 as still existing in many places in this country. Amongst the 

 lesser volcanic vents might be mentioned Slieve Mis, near 

 Ballymena, where the last eruption has consolidated in the 

 pipe through which it outflowed. Another small vent pipe 

 was passed at Ailsa, about one and a half miles from Bushmills. 

 Another is pointed out near Ballyrudder, Glenarm, which is a 

 fine example of a volcanic vent ; there the basaltic pipe is seen 

 penetrating through the Chalk formation, which has been very 

 considerably altered by the heat ol the igneous matter, and the 

 usual compact white chalk has been converted into a crystalline 

 white marble like loaf sugar, and the usual black flint nodules 

 changed into a substance like white porcelain. As to the 

 Causeway itself, it has been generally found that basalt when 

 cooling has often one or two planes of cooling. If it be an out- 

 poured sheet of basalt these will be the surface upon which it 

 has outpoured, and its own top surface next the air, and in 

 these cases the planes of cooling will be approximately hori- 

 zontal. It has been found that basalt in thus cooling has a 

 tendency to form into columns at right angles to their planes 

 of cooling. These columns are entirely due to the action of 

 shrinkage while in the act of cooling. Now the Causeway 

 proper is simply a bed of basalt resting upon an ashy bed at the 

 level of low water, and is about fifty feet in thickness ; and as 



