198 Scientific Proceedings, Royal Dublin Society. 



the eastward of the granite area, and lying unconformably against 

 the Bray and Newtownmountkennedy tract of Cambrians, there 

 are more or less metamorphosed Ordovicians. In these there are, 

 apparently some interbedded masses, as also ctykes and other 

 intrudes of whinstone, euryte, and felstone ; while in the Cambrians 

 there are a few whinstones (diabase) and intruded courses of quartz- 

 rock. The quartz-rocks in the granite area has been already 

 mentioned. 



The whinstones, eurytes, felstones, and quartz-rock, altered or 

 unaltered, are very little used. In one place, as already men- 

 tioned (ante, p. 181), between Roundwood and Annamoe, a mass 

 of whinstone has been altered into ophyte (serpentine) , more or less 

 allied to the so-called " Swedish green granite." " The towns 

 of Carnew, Shillelagh, Arklow, Rathdrum, Wicklow, Newtown- 

 mountkennedy, and Bray, are situated in the slate district ; and 

 this stone has in these places been generally used for all buildings. 

 The rock produces large, flat-bedded stones, and makes good strong 

 rubble- work ; but being thinly laminated, it is not well suited for 

 cut-stone purposes, as it cannot be worked across the grain. Granite 

 is therefore almost universally used for this kind of work." ( Wil- 

 kinson.) Some of the towns enumerated above are in the Cambrian 

 area, where the rock used is rough slate, not the Ordovician schist. 



There are whinstones in different places suitable for paving- 

 setts. At the Rathdrum railway station, as also to the east of 

 the Ovoca River, there is a very similar stone : this was worked a 

 little, but injudiciously, the surface-stones only being wrought, 

 which gave the setts a bad repute. Further southward, or down 

 the valley, opposite Avondale demesne, in the townland of Shrough- 

 more there is a stone very similar to the Welsh stone so much 

 used in Liverpool. A little S. E. of the Ovoca railway station, a 

 whinstone is quarried for general purposes. Some years ago it 

 was made into setts for the Dublin market, but was not approved 

 of, as it was said to become slippery. A little westward of 

 Wooden Bridge a quarry was opened by Mr. C. S. Parnell, and 

 good setts made ; but the undertaking had to be abandoned, as 

 the agent of the property demanded too high a royalty. 



Big Rock, Arklow. — On this hill Mr. C. S. Parnell has opened 

 quarries. " Four varieties of whinstone are worked — three blue, 

 and one slightly greenish. The setts made are — No. 1, 4" x 4" x 4"; 



