366 jiccount of the iVliynn Dykes in the 



that these loadstone strata were formed by successive erup- 

 tions of a volcano at the centre of the earth, which pouring 

 up repeated torrents of hquid lava, these spread when they 

 approached the surface of the earth at difl'erent distances, 

 and formed the toadstone strata. 



When Mr. Mills endeavours to establish his opinions 

 by assertions relative to my country, I will venture to re- 

 ply to him. 



The precipice from which the whytm dvkes issue at 

 Ballycastle, by his own account, consists of alternate strata 

 of freestone and coal, not very like volcanic matters: and 

 as to his positive and general assertion, that our basaltic 

 country confessedly abounds with volcanic matters, I must 

 reply in his own style, positively and generally, that it does 

 not afford a single particle of volcanic matter; that 1 have' 

 examined this tract for a longer lime, and probably with 

 more attention, than any other person ever did, or I would 

 not presume to hazard the assertion so confidently. 



When your lordship is so good as to perform the pro- 

 mise you made n>e, of spending some time with me at the 

 Giant's Causeway, you will be able to judge for yourself 

 as to the truth of these contradictory assertions. 



The advocates for igneous operations over the surface of 

 our globe are so prejudiced, that it is sometimes sufficient 

 to refute them merely to quote their own words. As 

 Mr. Mills's paper is now before me, [ will give your lord- 

 ship an instai^ce : He says, (page 98,) '< In short, from the 

 very rude and irregular appearance of the summit of the 

 hill (Loffit hill), from its rising so suddenly from the lime- 

 stone strata, and from the whynn dyke that runs through 

 it, I am strongly inclined to believe it of volcanic origin." 

 Now, as limestone and volcanic matters are not very con- 

 genial, and as we do not find that a whynn dyke has been 

 met with in the neighbourhood of any volcano, I conceive, 

 with great deference to Mr. Mills, that if he was deter- 

 mined to draw a conclusion' from these data, it should 

 have been a contrary one.— But it is time to proceed to 

 facts. 



The westernmost vvhvnn dyke I have met with on our 

 coast, is near what is called the Black Rock, at the end of 

 the Bush Strand. The perpendicular precipice is there 

 not very high (probably 6() feet) ; it is composed of hori- 

 zontal strata of table basalts, separated from each other by 

 red ochreous layers. 



The dyke (which is inaccessibTe) i.^ seen from the water- 

 tu cut all these strata rertically, each of them bemg inter- 

 rupted 



I 



