328 The Irish Naturalist. 



agents that have been suggested as having effected the trans- 

 port of this Scotch rock, seaweed would in this instance 

 appear to be excluded, both by the size of the block, and by 

 the distance which it has travelled. Large fragments of Chalk 

 flint were found, one sharp-edged piece measuring 8" x 6" x 6". 

 A fine boulder of rhyolite or quartz porphyry occurred, 

 probably from Forkill in Co. Armagh ; and near at hand 

 was a large fragment of Coal-measure sandstone, streaked 

 with undulating layers of coarse muscovite and carbonaceous 

 matter, similar to sandstones which occur at Coalisland, Co. 

 Tyrone, and Ballycastle, Co. Antrim. There were also blocks 

 of Carboniferous limestone of considerable size, one being 2 ^ feet 

 long by 2 feet broad ; and one of Old Red Sandstone measur- 

 ing i' 6" X \ 6" X r. Leinster granite was rare, but one grand 

 block was seen in sittc near the base of the Boulder- clay, 

 rounded, with a rough unscratched surface, and measuring a 

 yard in diameter. 



It will be seen from a consideration of the travelled fossils 

 and rocks described above, that while many of them may 

 have been derived from the north-east of Ireland, this cannot 

 have been the case with all. The Ailsa Craig rock must 

 certainly have come from the Clyde, or from some of the 

 islands to the north of it. We know furthermore that Ireland 

 furnishes Liassic fossils of the lower division only, and to 

 e:jiplain the presence of Middle and Upper Lias fossils we are 

 driven again to the Hebrideaii islands, where the zones which 

 might have furnished them have been shown to exist by 

 Judd"^ and others. And if the riebeckite-granophyre and a 

 portion of the Lias fossils had their source in the Inner 

 Hebrides, some of the basalts also may have come from this 

 region. 



The occurrence in the clay of Liassic and Chalk foraminifera 

 corroborates in a remarkable manner the evidence of the larger 

 Liassic fossils and the travelled blocks ; all these derived 

 foraminifera are found in the secondary rocks of Antrim, and 

 none of them elsewhere in Ireland ; but, as in the case of the 

 larger fossils and the erratics, some of them may have had 

 a Scotch origin. 



*See Judd, "On the Secondary Rocks of Scotland," QJ.G.S. 34, 

 (1S78), p. 660. 



