Kjnahan — On Irish Arenaceous Mocks. 549 



west of Rathmullen, have been used for facing in Ramelton. 

 In the valley about a mile south of Creeve Mountain, in the 

 townland of Oughterlinn, there are flags ; these are good, hard, 

 and silicious, and can be raised of large dimensions — 12 feet long 

 by a width of 4 to 6 feet. They have been used in Ramelton ; but 

 the place is very inaccessible, the road being very bad. To the 

 north of Rathmullen, in places near Lough Swilly, there are also 

 flags that have been worked for local purposes, especially in the 

 neighbourhood of Long Lough. 



In the quartzyte range of Knockalla some of the quartzytes 

 are thin-bedded. They are silicious and hard, and appear as if 

 they could be raised in marketable sizes. These, as yet, have not 

 been opened on ; but, if they could be obtained of sufficient sizes, 

 they should be valuable. Up to the present the place has been 

 very inaccessible ; but as a pier has been erected in Ballymastockan 

 Bay, at Croaghros, they are now near a port. At the opposite 

 side of Lough Swilly, in Dysertegney, Inishowen, these beds are 

 worked, and produce good flags, that ought to be more utilized 

 than at present. 



There are also veins of more or less similar flags in the north 

 of the county, near Crossroad and Dunfanaghy, which are locally 

 used. 



[The age of the rocks in the north of Donegal is still undetermined. For some 

 reasons they might be supposed to belong to the later groups, while there are also 

 reasons for supposing they are portions of the older. The geology, however, here- 

 abouts is so complicated, the younger and older strata being folded in sharp inverted 

 curves, that it is quite possible that their exact age will never be satisfactorily known.] 



In the barony of Raphoe none of the sandstones have been 

 considered specially suitable for cut-stone purposes, although they 

 are very useful for walls. Those which can be raised in large blocks 

 are good for coarse and heavy work, such as foundations and the 

 like. In a few quarries, however, the stones have been used for 

 dressed work, and they cut fairly well. They, however, are liable 

 to discolour. 



Muckish. Three miles from Dunfanaghy. — Quartzyte; open 

 and porous ; pure white ; semi-crystalline ; slightly foliated ; very 

 slightly calcareous. 



Kinclevin. Nearly a mile from Dunfanaghy. — White quartzyte. 

 with minute divisions of mica. 



2P 2 



