46 PROF. T. G. BONNET ON THE [Feb. 1896, 



We have already pointed out l that the Lizard affords two fairly 

 distinct types of serpentine — one, that more generally known, 

 containing distinct . grains of bastite (e. g. Xennack Cove), and 

 sometimes augite in addition (e. g. Coverack Cove) ; the other, in 

 which the bastite, if present, is inconspicuous, while small crystals 

 of white hornblende are abundant (e. g. south of Mullion Cove) : the 

 former being most abundant on the eastern, the latter on the western 

 coast. 2 But we find the bastite-serpentine on the west coast to the 

 south of Kynance Cove, 3 and again on the actual headland of the 

 Rill. Here, also, within a short distance, the peculiar variety 

 of serpentine occurs which has been said to contain felspar, 4 but I 

 could not discover how they were related. Prom north of Kynance 

 to Gue Graze the dominant serpentine is a rather compact, slightly 

 streaked rock, which on the whole seems more nearly related to the 

 hornblendic than to the bastite-serpentine. The hornblendic ser- 

 pentine also occurs, though not abundantly, on the east coast ; that 

 at Porthallow 5 on the whole more nearly agrees with it than with 

 the other ; we find it on the shore for some little distance south of 

 Poltesco Cove and from Cadgwith to Carnbarrow. But the most 

 curious instance is at Kildown Point. In the quarry at the top we 

 find the bastite-serpentine, while the mass at the foot of the cliff 6 

 is a very typical hornblende-serpentine. I regret that I have not 

 from the first recorded the variety of serpentine in each quarry or 

 outcrop examined ; but, so far as I remember or have noticed, the 

 serpentine, at places within a curved line drawn from Coverack to 

 Kynance Cove, roughly symmetrical with the eastern coast, is 

 generally the bastite variety, and that outside this line is the horn- 

 blendic variety, including with it the dull compact type already 

 mentioned. 



Green Schists of the Southern Coast. — We paid special attention 

 to the relations of these schists with the normal hornblende-schists, 

 and are more than ever satisfied that, as stated by Gen. M c Mahon 

 and myself, they are only the latter rocks modified by extreme 

 pressure. 7 In more than one place we were able to trace a gradual 



1 Quart. Journ. Geol. Soo. vol. xxxix. (1883) p. 23, and vol. xlvii. (1891) 

 pp. 466-468. 



2 Sp. gr. (mean) of four specimens of the former (two determined for this 

 paper) 2*62. Sp. gr. of three specimens of the latter (two determined for this 

 paper) 2*755. 



3 As in the sections near the Lion Rock, described by Messrs. Fox and Teall. 



4 I remain sceptical as to the identification of this mineral with felspar, 

 though I believe it to be an aluminous silicate. 



5 Its sp. gr. ranges from 2-545 to 2-644 (J. H. Collins) ; that of the Eill is 

 heavier, 274 ; that of Gue Graze heaviest of all, 2"85 (M. W. Travers). 



6 See p. 30. The sp. gr. of a serpentine such as that at the top is 2 - 653, of 

 that at the bottom is 2-698, which is very nearly that of the west coast serpentine. 



7 In regard to this my work in the Alps during the last few years has been 

 very helpful; see Quart. Journ. Geol. Soc. vol. xlix. (1893) p. 94, and vol. 1. 

 (1894) p. 279. [As this admission was quoted by a speaker in the debate to 

 justify the extension of ' dynamo-metamorphism ' to the whole region, I must 

 point out that, by admitting a certain cause to have produced marked modi- 

 fications in two very limited parts of a district, we, in effect, exclude it from the 



