Prof. T. G. Bonney — Remarks on Serpentine. 409 



hornblendic and the granulitic series, ranging from a few feet to 

 Several yards in length, and of variable breadth and thickness, are 

 completely included in the serpentine, the lines of parting being 

 often perfectly sharp and unmistakeable, and the "schist" often having 

 a " baked " and slightly altered aspect. The serpentine also some- 

 times assumes near the junction a slightly different aspect. These 

 instances, two of which are figured (tlie woodcuts are ill executed) 

 in my paper on the Lizard serpentine, may be counted by dozens on 

 the eastern shore. 



In short, if there be in Nature any indications from which ive can 

 as^sert the intrusive character of any igneous rock whatever, we have 

 these indications in the case of the Lizard serpentine and the 

 associated sedimentary series. 



I repeat this statement at some length, because of a passage which 

 Dr. Hunt penned about six years since, and has repeated in effect in 

 the paper which I am noticing. " When it is considered that there is 

 abundant evidence that the North American serpentines are indi- 

 genous, though often like deposits of gypsum and iron ores in 

 lenticular masses : and further, that the movements which the ancient 

 strata have suffered, have produced great crushings and displace- 

 ments, it is not difficult to understand the deceptive appearance of 

 intrusion wliich these rocks often exhibit, and which are scarcely 

 more remarkable than the accidents presented by coal-seams in some 

 disturbed and contorted areas." 



This passage is an excellent example of the length to which an 

 immoderate indulgence in a theory will produce mental intoxication. 

 Dr. Hunt, I have reason to believe, has never set foot in Cornwall, 

 and apparently is too "elevated " even to read my descriptions with 

 any care ; or he would see that the only meaning of this passage 

 would be to assert that I have not had that field experience 

 which enables me to offer an opinion on a petrological question. I 

 do not like to speak of myself, still I may say that my experience is 

 probably not less than his own, both in the examination of disturbed 

 and contorted areas and in the study of the behaviour of intrusive 

 igneous rocks ; that the one great endeavour of my life has been, 

 not to evolve geological facts from my moral consciousness, but to 

 accept the teaching of Nature, whether it suited my theories or not ; 

 and that, having thrice visited Cornwall in this spirit, I simply repeat, 

 that if there are any indications whatever on which we can rely for 

 proving the intrusion of one rock in a plastic condition into another, 

 these are exhibited by the serpentine of Cornwall. 



I pass on to the other regions which I have visited. 



Anglesey. — The evidence here does not, as in Cornwall, prove the 

 serpentine to be intrusive, but accords far better with this explana- 

 tion than with any other. 



Scotland. — (Ayrshire) I do not think it possible to explain the 

 appearances on any other theory than that of intrusion. (Portsoy) 

 My visit was short ; what I saw was favourable to the idea of in- 

 trusion, though it did not prove it. 



The Alps. — Of six cases specially examined, in one case either 



