The Rev. D. Williams's CliffSection of Lundy Island. SI 



stages of mineral variaiion, between the extreme terms of 

 typical granite passing b}' calcareous granite, syenite, black 

 compact hornblende trap, greenstone porphyry, and greenstone 

 ash or mud, into clay schist and crystalline slate (the proxi- 

 mate eflfecls of a great physical constant), linked together in 

 such a ehiiin of mutual relations and dependences as demon- 

 strated their codimon source and origin. 



The author had met with the same connected mineral series 

 in every ancient volcanic group of Devon and Cornwall, from 

 the focal granite lava to the finely levigated and impalpable 

 mud, oftentimes in more full and circumstantial particulars 

 than were detailed at Lundy Island ; but, on the other hand, 

 the daily washed and unambiguously disclosed sea-clifF sec- 

 tio)is of the latter, satisfactorily explained to his mind the in- 

 tervaled but reiterated occurrence of those enormous masses 

 of hypersthene and greenstone on the flanks and immediate 

 confines of the several granite domes, and which often ap- 

 peared to pass by syenite into the granite, but whose relations 

 to it otherwise were concealed. Wherever he had met with 

 those masses of greenstone, &c., he had never met with granite 

 veins penetrating the bounding rocks, whereas they were uni- 

 formly more or less present in the intervals of their occur- 

 rence. There, as at Lundy, the bounding sedimentary rocks 

 in the one case showed little or no amount of alteration, in 

 the other they were changed to a vast amount and extent, and 

 exhibited all the varying phases or stages of reduction, from 

 perfect fusion to semifusion and incipient induration. 



The remarkable proportions of lime in certain of the Lundy 

 series, constituting, as it did in some of the terms, far beyond 

 a moiety of the component ingredients, gave undeniable proof 

 of the occasional presence of lime in granite and its cognate 

 thermogenous rocks ; so that lime is not invariably so defi- 

 cient a substance in this class of mineral compounds as had 

 commonly been supposed; while the instances he adduced 

 naturally suggested the inquiry, why such deficiency should 

 exist in the majority of cases. 



He regarded it as an altogether fabulous assumption, and 

 a necessary corollary of the day-dream ot the solar, or fire- 

 niist origin of granite, that at any period of the earth's history, 

 lime should have been in a less proportion than it bears at 

 present to the other elementary earths. Such fabulous origin 

 o( granite, combined with the supposed absence of lime in it, 

 suificiently explains the contrary supposition which has Ijecn 

 advanced ; while the sequel hypothesis, which attributes the 

 present amount of lime in nature to the polyparia and mol 

 lusca, — in other words, that creatures whose existence at all 



