588 Scientific Proceedings, Royal Dublin Society. 



morpliosed. Some of the purplish sandstones and conglomeritic 

 rocks can be raised in large blocks, and would be suitable for cut- 

 stone purposes ; but, on account of the facilities for procuring 

 excellent limestone, they, in modern times, have been rarely- 

 thought of, except near Newport, where some of them have come 

 into favour. In 1845, Wilkinson thus writes of the sandstone 

 then in favour in that town : — " It varies from a conglomerate or 

 coarse-grained sandstone to a very hard red and brown and 

 whitish-coloured grit. This stone is now generally used for all 

 purposes, and is quarried within a mile of the town on the east. 

 The bridge of Newport has the spandril erected with a fine red- 

 coloured grit obtained from the neighbouring mountains." 



[In this neighbourhood the Silurians of the " Old Eed type" and the Lower Car- 

 boniferous Sandstones are rather mixed, being often very similar in colour and texture, 

 so that, except from personal examination in the quarry, one cannot be distinguished 

 from the other. Most, if not all, of the sandstones mentioned by Wilkinson as used in 

 Newport seem to have come from the tract of Silurians a little eastward of the town ; 

 but some of them may possibly have been obtained from the Lower Carboniferous 

 Sandstones of the vicinity.] 



To the east of the county, between Charlestown and Ballagha- 

 derreen, there is a tract of Silurians. In this the rocks above 

 and below are of the " Old Eed Sandstone" type, while between, 

 are green sandstones, with subordinate calcareous and shaly beds 

 that contain Silurian or Llandovery fossils. 



[The green sandstones are peculiar, because, except in colour, they are identical in 

 composition with the rocks above and below them. The fossils occur in three horizons- 

 Those below are of Llandovery types ; the middle beds contain fossils of "Wenlock 

 types, while in the upper beds they are again of Llandovery types. This, therefore,, 

 is an example of the places in which fossils typical of English groups cannot be taken 

 as a positive indication of age ; — these rocks, as suggested by Griffith, Jukes, and 

 Foot, are probably in part the equivalents of the " Dingle beds" and the " Glengarriff 

 grits" of the counties of Cork and Kerry: that is, the upper beds of the Silurian 

 closely allied to the Devonians or the Passage Beds between the Silurian and the Carbo- 

 niferous.] 



In both the rocks of the reddish and greenish types are some 

 good workable stones, that have been extensively used for building 

 purposes, both in Ballaghaderreen and Charlestown. Some of 

 them seem to be capable of producing good dressed work ; but, as 

 they have been principally used in rough walling, their capacities 



