246 



the southern dip of the rocks it could perhaps be traced a little inland 

 from the top of the precipice. The bed of limestone, which is 148 feet 

 below the coal, rises sufficiently high to be visible in the face of the 

 cliff all the way in this division. From the anticlinal position all the 

 rocks at the west side of this colliery dip west, and all those at the east 

 dip east. The dip in both is about 1 0°. 



Ko.s. 5, 6, 7, 8, 9, are all much alike. The rocks have a general dip 

 eastward. The coal crops out in the cliff in all, but at different heights, 

 as stated in the table. 



No. 10. Gobb Mine. — In this the rocks assume a synclinal position, 

 and in the hollow formed by this downward curve flowed the trap which 

 caps the summit, and is fifty-one feet high there. The precipice pre- 

 sents no appearance of a fissure, through which this trap might have 

 been erupted. The mass of trap probably flowed southward in the syn- 

 clinal hollow before mentioned from the source, which might have been 

 a crater lying to the north. 



11. The Portnagree Division has a western dip in its beds. The 

 whole block stands at a lower level than the Gobb colliery, and either 

 it slipped down, or the Gobb was upheaved. 



There are in the cliff here seven whin dykes, and five clay dykes 

 separating those collieries. Some clay dykes are one, two, or three feet 

 thick. 



It is probable that the whin dykes and the clay dykes are of two 

 different periods as to age. The whin dykes first, when the subterra- 

 nean gases and other matter were in an expanding condition ; the clay 

 dykes afterwards, when the whole mass was cooling, and blocks 

 slipping down from their equivalents, along fissures made in the rock 

 from cooling by contraction. 



The effect produced by those dykes upon the Ballycastle collieries, 

 that of dividing the rocks of the coast into distinct blocks or divisions, 

 is to be seen in other places. A similar disposition of such blocks, se- 

 parated by dykes and slips, occurs on the shore on the south side of 

 Belfast Lough at Cultra, five miles from Belfast. Here there are seven 

 or eight dykes, running nearly parallel to each other, and at right angles 

 to the shore, which separate the Permian rocks of that place into divi- 

 sions. Those divisions of the Permian and coal rocks are thrown up 

 and down, exactly similar to those at Ballycastle, Here, however, 

 there is no high cliff in which the amount of the dislocation can be mea- 

 sured. The tops of all the blocks are under high water mark, and nearly 

 level ; but the variety of colour in the yellow and red sandstone, and 

 the yellow, red, and gray limestone of the Permian rocks, and nearly 

 black coal shales, which occur near them, show that different zones 

 of the group come into juxta-position at the surface, and that the 

 blocks at this place between the whin dykes have been thrown up 

 and down from their original position, like those at the collieries at 

 Ballycastle. 



The northern shore of Antrim, from Ballycastle westward by the 

 Giant's Causeway to the Bann, presents similar phenomena. It has 



