24 PROCEEDINGS OF SOCIETIES. 



probably made up of a series of small contortions, from north to south, 

 across the valley, repeating the same beds over again, and thereby dimi- 

 nishing the apparent thickness we should otherwise have of these beds. 

 Along the northern side of the river Koughty the limestone is seen to 

 form rough mounds and rocky knolls here and there in the ground, 

 being quite massive in outward appearance, but still seen to retain the 

 usual laminated and slaty structure when fractured, and often contained 

 irregular bands of chert. I remarked that the dip surfaces of the rocks 

 which face the valley are much water- worn and rudely furrowed by 

 water-action in that direction. If we now trace this limestone from 

 Clontoo, a little south of Ardtully copper mine, eastwards, we see that 

 immediately east of this place it suddenly changes the hitherto constant 

 strike, and becomes much contorted on its northern boundary. Coming 

 round to the south to Ardtully House, close to which there is a quarry, 

 in which the limestone is seen to have a northerly strike, dipping south- 

 west at 70° north. Close to this quarry at Fassa Bridge the blue and 

 black slates and shales, similar to those beds noticed as the rocks on which 

 the limestone rested at Roughty Bridge, on its southern boundary, are 

 seen dipping under the limestone. From Ardtully House the limestone 

 forms an irregular boundary eastwards, and being contorted, and curving 

 round to the north by Fassa Bridge, is again seen, about 500 feet east of 

 the latter place, in a large quarry close to the old road to Kilgarvan, 

 dipping south at 60°, and resting upon the black and blue slates and 

 shales mentioned as occurring at Fassa Bridge. From this the northern 

 boundary of the limestone continues pretty steady in an easterly direc- 

 tion to the police barrack, situated at the west end of the village of Kil- 

 garvan, and is seen constantly in junction, or nearly so, with the black 

 and blue shales and slates which bound it on the north from Fassa 

 Bridge. But, before leaving Ardtully, I would beg to notice the sudden 

 manner in which this band of limestone, and the rocks southwards 

 (hitherto seen to form a broad band across the valley) narrow from 

 Clontoo to Ardtully. Between Ardtully and Roughty Bridge, on the 

 southern boundary of the limestone, immediately north of Kilgortaree 

 House, on the map, we see the same rocks as we have at Roughty 

 Bridge, viz., gray grit, slates, &c, dipping still north at 80° south of 

 Ardtully House, and in the bend of the river Roughty a good section of 

 the limestone is seen. The beds seem to dip south at 75°, consisting of 

 massive pale gray limestone, then thin beds of fine crystalline lime- 

 stone, with hard siliceous layers weathering out like chert bands, which 

 are succeeded by thin beds of white and greenish compact marble, 

 separated again by thin layers of pale greenish shale, which do not appear 

 to be calcareous. These beds are seen again in the line of strike, a little 

 to the east of Ardtully Old Bridge, about a quarter of a mile distant from 

 this spot, and appear to dip still south at 55° in the former section ; 

 south of Ardtully, immediately south of the chert and siliceous lime- 

 stones, we see dark red and purple slates and grits apparently dipping 

 north at 80°. If these dips be correct, there must necessarily be a fault 

 along the southern boundary of the limestone cutting off some of the 



