XXX PROCEEDINGS OF TfiE GEOLOGICAL SOCIETY. 



eminently characterized his scientific oratory. In 1813 he visited 

 the north of Ireland, in company with the Rev. W. D. Conybeare 

 (now Dean of LlandafF), and the result of that most interesting vaca- 

 tion tour was published in the Transactions of our Society, 1816. 

 It must be remembered that the discussions between Neptunists and 

 Volcanists had not then ceased, and that in this most remarkable 

 basaltic district the controversialists found ample materials for their 

 respective arguments. The curious indurated porcellanic schist of 

 Portrush, full of ammonites, having been confounded with true basalt, 

 was eagerly cited as a proof, that basaltic rocks generally had been 

 in a state of aqueous solution or suspension. Nothing could have been 

 more sound than the analogy drawn by Dr. Richardson between the 

 Portrush schist and other calcareous or argillaceous strata containing 

 organic remains ; his error was, in considering the Portrush rock " a 

 fine basalt," and thus extending this analogy to the true columnar 

 basalt of the adjacent district. Playfair pointed out the error of this 

 reasoning, but it was still clung too, founded as it was, upon an im- 

 portant fact, which then remained isolated or without apparent 

 connexion with the general phenomena of the district. The obser- 

 vations, however, of the Rev. W. D. Conybeare and of the Rev. W. 

 Buckland strengthened the opinion of Playfair, by showing that 

 these indurated strata were, by their organic contents, related to 

 the strata of the adjacent country. About half-way between Bally- 

 castle and Bushmills, near Ballintoy, the chalk formation rises 

 sufficiently high to disclose its sub-strata : a valley opening to- 

 wards the sea, near White Park, shows that they here consist of the 

 slate-clay of the lias formation, with gryphites and ammonites* 

 Farther west the chalk cliffs again emerge from the level of the sea^ 

 immediately beyond Dunluce Castle, and continue to rise till they 

 are broken oft' at the commencement of the Portrush Strand. As 

 they here exhibit nearly the same thickness which they possess near 

 White Park, we are naturally led to expect the recurrence of similar 

 sub-strata near this point, and accordingly in the peninsula of Port- 

 rush, a singular rock is seen divided by interposed masses of green- 

 stone, but containing ammonites and gryphites, and possessing ex- 

 actly that character which would be assumed by the slate- clay before 

 described, if indurated by the action of heat. " The peninsula itself," 

 they observe, " which may be about a mile in circumference, is fenced 

 with low cliffs on the west, north, and east ; those on the west pre- 

 sent a rudely prismatic greenstone, those on the north and east tabular 

 masses of greenstone, overlying, and in some places appearing to 

 alternate with, a very remarkable rock, which has been the subject of 

 much discussion among the supporters of opposite theories. It is a 

 flinty slate, exactly similar to the indurated slate-clay which forms 

 the wall of the Carrick Mawr dyke in the Bally castle collieries ; and 

 the analogy is rendered the more striking from the further resem- 

 blance of the greenstone of that dyke to the greenstone of these cliffs. 

 In this flinty slate are contained numerous impressions of Cornua 

 ammonis invested with pyrites, the shells being similar to those found 

 in the slate underlying the chalk near Ballintoy:" and "we felt 



