Page:Transactions of the Geological Society, 1st series, vol. 3.djvu/147



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 primitive limestone which contains crystallized hornblende in abundance: 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.