55*$ [Proc. B.N.F.C., 



found an abundant supply of flints — some inter-bedded in 

 situ, and some weathered out and exposed, ready to the hand of 

 the flint manufacturer, as at Glenarm and the headland of 

 Garron Pont. 



As already stated, the flints were, no doubt, objects of interest 

 to primitive man, as they continue to be with the modern 

 naturalist, who finds it difficult to account for such quantities of 

 flints inter-bedded with purely limestone rocks, that are other- 

 wise so free from any silicious material. 



Our white limestone, or Chalk, originated as a marine deposit, 

 laid down in a remote period of geological time, as its fossils and 

 microscopic structure testify, and yet we have no flints in our 

 modern sea-bottom, or anything that may be considered 

 equivalent to the flints of the Chalk. 



The voyage of the " Challenger " has thrown some light on 

 this question, and Sir Wyville Thomson has shewn that silica, 

 to the extent of from 30 to 40 per cent., occurs in the deep-sea 

 mud, or ooze, to which the spicules of sponges and radiolarians, 

 and the frustules of diatoms largely contribute. And while he 

 recognises the difficulty of giving a satisfactory explanation of 

 the origin of flints, he suggests that "the organic silica distributed 

 in the shape of sponge spicules, and other silicious organisms of 

 the Chalk, had been dissolved, and reduced to a colloid state, 

 and accumulated in moulds formed by the cells, or outer walls, 

 of embedded animals of various classes." In this manner 

 ventriculites, sponges, and similar organisms would become the 

 receptacles of the silicious material, and thereby assume the form 

 and property of what we now know as flints. 



This material, so abundant in the white limestone of the 

 counties Antrim and Derry, as already described, was the stock- 

 in-trade of the primitive Irish manufacturers, and from this they 

 fabricated the worked flints that are considered such interesting, 

 and, indeed, necessary additions to the collections in the museums 

 of Europe and America, from the simple flake, scraper, and arrow- 

 head, to the elaborately chipped, polished, and systematically 

 formed spear-head. 



