The Rev. D. Williams's Cliff Section of Lundy Island. S3 



Another irresistible induction presented itself in the Lundy 

 series. The most fiistidious mineralogist, if he admitted gra- 

 nite to be a physical substance, and not a metaphysical abs- 

 traction, must concede that the specimen No. 2 on the sec- 

 tion, was granite modified by a very trifling accession of horn- 

 blende. But this necessary admission will conduct him by a 

 series of insensible gradations to the inevitable conclusion, 

 that the calcareous dark green porphyry and the black horn- 

 blende trap or greenstone are nothing else than granites in 

 disguise, or granitic matter masked in colour and modified in 

 substance, by the accession of varying proportions of horn- 

 blende and lime, and no doubt other adventitious minerals. 



The cabalistic traditions of cosmogony which leaven the 

 whole lump of geology at the present hour, and which rigor- 

 ously excluded a particle of hornblende and lime from granite, 

 nevertheless included (no doubt from their universal associa- 

 tion) slate and schist in the category of granite and the primi- 

 tive formations. Yet what geologist, he asked, in the present 

 day, would venture to talk of primitive or primary slate and 

 schist? 



If these slates and schists, then, were demonstrably neither 

 azoic, protozoic, primitial, primitive or primary — if, in truth, 

 they were of all dates, from the most ancient to the newer 

 pliocene, the granites and their congeners were the same. 

 There was a negative fact, too, which (in the universality of 

 its negation, accompanied, as it was, by such an accumulation 

 of probable and circumstantial testimony as amounted to 

 the best positive evidence,) led to the same conclusion. If 

 granite were a primary and independent substance, a sort oi 

 mineralogical fact but a metaphysical abstraction, as the cos- 

 mogonists still hold, it assuredly ought to occur, at times at 

 least, unaccompanied by, and apart from, its present universal 

 associates, which it assuredly does not in any portion of the 

 globe which has hitherto been explored. On the contrary, 

 the author was prepared to show, that the same predominant 

 mineral tj/pes, or the same average proportion of constituents^ 

 characterized, alike the granites, porphyries, serpentines, green- 

 stones, slates and schists, of any tioell-defined division of the 

 Devon and Cornish group. 



In the Lundy series we eliminate the important truth, how 

 egregiously we may be, and doubtless have been, imposed 

 upon by the varying accession of one deceptive compound ; 

 the minimum amount of hornblende in No. 2 demonstrating, 

 by the aid of the intermediate gradations, that its maximum 

 of imposition in Nos. 6 and 8 is simply a question of degree ; 

 while from the conditional fact or accident of its absence in 



Phil. Mag. S. 3. Vol. 35. No. 233. Jtdy 1849. D 



