of the North of Ireland. 139 



C. Primitive Limestone. 



Primitive limestone exists in several parts of the counties of 

 Antrim and of Londonderry as a subordinate member of the mica 

 slate formation with which it sometimes alternates. 



Granular and blue micaceous limestone, with veins of coloured 

 spar, quartz, and green chlorite, occurs on the north-west side of 

 Cairntogher, in the county of Londonderry, at the height of about 

 800 feet above the level of the sea. 



The same granular and micaceous limestone exists in Bennady 

 Glen, and at the old church near Dungiven, at the latter place 

 in large lamellar concretions, passing into compact with a greenish- 

 grey colour : at Banagher church it occurs blue, micaceous, and 

 in small granular concretions. Near Clady, on the road from 

 Dungiven to Londonderry, it is extremely talcky with some 

 quartz nodules ; and in the deer park of Mr. M'Causland, near 

 Newtown Limavaddy, it possesses the same character, containing 

 some thin layers of quartz and a few iron pyrites. 



Lastly, on the north-east side of Slieve Gallion, there is a pri- 

 mitive limestone which contains crystallized hornblende in abun- 

 dance : it breaks spontaneously into large rhomboids, incrusted 

 over the natural joints with calcareous spar, of a green-yellowish 

 colour. 



At the point of Taur in Antrim, the colour of the limestone 

 varies from grey to reddish grey, and greenish grey ; the concretions 

 are rather large, and the texture passes sometimes from granular 

 into compact ; it contains only a small quantity of magnetic iron 

 pyrites. 



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