Kinahan — On Granite and Metamorphic Bocks. 229 



In this neighbourhood, as also to the north-east of Lough 

 Grara, there are some large dykes of whinstone. 



Some of the whinstones are utilized as road-metal, and the 

 eurytes and tuffs rise in nicely-shaped and sized stones, suitable 

 for walling, while they seem to be capable of being dressed. Some 

 of them cut and polish well, and might be employed for ornamental 

 purposes ; none of them, however, seem to be made use of, except 

 for farm fencing. They are at high elevations, and generally not 

 easily accessible, while sandstone abounds. 



More or less similar rocks occur also in the western part of this 

 hill range, near Ballaghaderreen, and in the Charlestown district. 

 Some of the latter, however, are intrudes, unaccompanied by 

 tuffs. 



At the western extremity of the range (Co. Mayo), appearing 

 from under the Silurians, there is a small tract of metamorphosed 

 rocks, probably Ordovicians, appearing from beneath the Silurians. 

 These rocks are more baked than micacised, many of them being 

 leptinytes, or white-rock; these are represented on the geological 

 survey map as felstone. They are generally very pure stones, and 

 should be capable of being manufactured into kaolin. In this 

 tract there is also an intrude of euryte, and smaller ones of a 

 pyroxenic-hornblendic rock. The latter is a nice-looking stone, 

 cutting and polishing well ; but it is excessively hard, and rises in 

 rather ill-shaped blocks. 



In the townland of Uggool, near the north side of the 

 mouth of Killary Bay, there is a tract of el van, a small piece of 

 which cut and polished well ; it is of a mottled yellowish red or light 

 salmon colour. 



South-east of Drumsna, Co. Leitrim, in the Ordovicians, there 

 is a small boss of whinstone. 



In the promontory called the Eosses, three to four miles north- 

 west of the town of Sligo, there is a small exposure of metamorphic 

 rocks. They are principally schists. 



DONEGAL, LONDONDERRY, TYRONE, AND FERMANAGH. 



Of the rocks in this part of the territory, those of Donegal are 

 the most important. 



