On the Probable Mode of Transport of the Fragments of Granite and other Rocks which are found imbedded in the Carboniferous Limestone of the Neighbourhood of Dublin

Abstract

For some time I have been endeavouring to obtain specimens of the limestone containing fragments of granite which were first found nearly forty years ago in the neighbourhood of Dublin. The quarries being now filled up and inaccessible, I followed on the track suggested by having observed a specimen built into a garden wall, and through the aid of Mr. H. B. White, M.E., I was enabled to discover a wall in which such specimens occurred in considerable abundance. The permission of the owner, Dr. E. P. Wright, having been obtained, a fine series of blocks, in which the granite was visible, was delivered at the museum; these, after they had been trimmed and split by a stone-mason, afforded such a variety of beautiful specimens that I have thought it would interest the Society to exhibit a selection of them, as I believe comparatively few geologists have had an opportunity of examining anything of the kind. The examination of these specimens has revealed the presence not only of angular fragments of granite but also of schist, quartzite, and vein-quartz, such as might have been derived from the metamorphosed Silurian rocks which rest on the granite near Dublin, and are in one locality exposed in a sea-cliff at the base of Killiney hill. As a rule, these fragments, though in some cases permeated with calcareous matter, show little if any signs of of decomposition; the surfaces of contact with the enveloping limestone are sharp and clean, and the adhesion is very