294 SCIENCE IN SHORT CHAPTERS. 



would result from the slow baking of a mass of boulder 

 clay. 



The sea gully that separates the insular rock from the 

 mainland displays a fine section above eighty feet in thick- 

 ness, and has the advantage of full daylight as compared 

 with Dunluce Cave. That this is no mere neck or pipe is 

 evident from its extent. Its position below the basalt cap 

 refutes the above quoted subsequent explanation, which 

 Mr. Hull and others have recently adopted. 



The heterogeneous bomb-like character of the boulders 

 is not so strongly marked as in the Dunluce rock, and this 

 may arise from the closer proximity of the basalt, which, 

 coming here in direct contact, would be likely to heat the 

 clay matrix (itself formed mainly of ice-ground basalt) to 

 incipient fusion, and thereby render it more like the basalt 

 boulders it contains than the other clay that had been less 

 intensely heated on account of greater distance from the 

 lava-flow. 



The path leading to the ladder by which the bridge is 

 approached passes over such conglomerate, and further 

 extensions are seen in sections around. I saw sufficient in 

 the course of my hurried visit to indicate the existence of 

 a large area of this particular formation. 



At a short distance from Carrick-a-Rede, on the way to 

 Ballycastle, the car passes in sight of considerable deposits 

 of ordinary boulder clay uncovered and unaltered. 



The blocks of basalt, etc., embedded in this correspond 

 in general size and shape with the " bombs," excepting 

 that some of the latter have a laminated, orshaly, character 

 near their surfaces. 



I regret my inability to do justice to this subject in con- 

 sequence of the fact that the above explanation of the origin 

 of this curious formation only suggested itself when hurry- 

 ing homeward after a somewhat protracted visit to Ireland. 

 As I may not have an opportunity of further investigation 

 for some time to come, I offer the hypothesis in this crude 

 form in order that it may be discussed, and either con- 

 firmed or refuted by the geologists of the Ordnance Survey, 

 or others who have better opportunities of observation than 

 I can possibly command. 



