Page:Transactions of the Geological Society, 1st series, vol. 3.djvu/214

 minute grains of iron pyrites. At fifteen yards distance from the dyke the alteration ceases, and the sandstone resumes its usual character, becoming reddish and destitute of pyrites. Where the dyke traverses the great insulated mass of slate, it is very irregular both in thickness and direction. The works of Gob colliery have reached, this dyke 500 yards inland from the face of the cliff: the coal is altered by it to a considerable distance from its point of contact, being reduced to the state of a cinder, which can be employed only for burning lime. This dyke throws out the measures of Gob colliery, which are not recovered on its eastern side: its breadth is about 12 feet where it comes to the surface of the cliff, but varies considerably in different parts of its course.

Immediately behind Carrick Mawr, an opening may be seen in the cliff which forms the channel of a torrent; pursuing this inland for the distance of about a mile it is found to issue from a small lake surrounded with basaltic cliffs. We were ourselves prevented from visiting this spot, but from the descriptions we received of it were led to wonder, that none of those who consider this country as volcanic had selected it, as a crater,

At some distance east from Carrick Mawr dyke is the Saltpans dyke, which also throws out the coal of Gob mine on the west; its breadth is eight yards. Still further is a thin dyke; both these alter the coal. North Star dyke follows. This is often cut through in the collieries, its breadth is eight yards: it does not shift the coal, but reduces it to cinder for nine feet on each side of its contact.

Where the cliff declines towards Ballycastle, the coal measures terminate abruptly, and are succeeded by trap rocks. It seems that this position must have been produced by a fault and subsidence.

Near Ballycastle a broad valley opens into the interior towards