Vol. 52.] ROCKS OF THE LIZARD DISTRICT. 31 



forming the southern, and serpentine the northern side of the 

 cove, and in the middle part a mass of granulite through which in 

 more than one place serpentine i breaks irregularly, exactly as it 

 would break through a rather hard sedimentary rock, in places 

 forcing back and crumpling up some of the bands.' l One mass of 

 serpentine, of which I made rough sketches, was about 4 yards long 

 and 2 wide. That also showed a slight foliation or nuxional structure, 

 and this too was nearly at right angles to the bands in the granulite. 

 All the way up the crags above this place we see outcrops both of 

 the one rock and of the other. 



I submit then, that these instances (and it would be easy to go on 

 multiplying them) show that the serpentine is really intrusive in 

 the ' granulite.' The former rock, however, must have been at this 

 time only in a semi-fluid condition — viscid and tough — so that it 

 was not able to do more than force its way occasionally along planes 

 of weakness in the ' granulite ' (blocks of which it often included 

 and perhaps tore away), softening the latter rock locally and 

 squeezing -it about, though the effect which it produced generally 

 extended only for a few inches away from the actual junction- 

 surface. 



(J?) Relations of the Serpentine to the Hornblende-schists. 



The best sections for studying these relations, so far as I know, 

 are at ' Potstone Point,' on the cliffs north of Ogo-dour, and at Hen- 

 scath, on the west coast ; at Carnbarrow and in Porthallow Cove on 

 the east. Except the first, these were well known to me, and of it 

 I had a general knowledge. All, however, have been carefully 

 examined. Pirst, with regard to the Potstone Point sections, of 

 which Messrs. Pox and Teall have given so admirable ah account. 2 

 These lead, in their opinion, to sundry conclusions, of which I quote 

 three, 3 as the rest need no further discussion : — 



* (1) The hornblende-schist and serpentine of the Ogo-dour district 

 form together a banded complex of crystalline foliated rocks. 



' (2) The relative ages of hornblende-schist and serpentine cannot 

 be satisfactorily determined, but the occurrence of lenticles of 

 serpentine in hornblende-schist points to the conclusion that, if 

 there be any difference in age, the serpentine is the earlier. 



4 (3) The complex of schist and serpentine has been folded after 

 the banding was produced, and before the dykes were intruded. 

 Some, if not all, of this folding probably took place when the com- 

 plex was formed/ 



Of these the second and third alone are important, because without 

 them the first, so far as I understand the word ' complex,' commits 

 us to very little. 



In this locality also the question between us is one of interpreta- 

 tion rather than of facts. I gladly avail myself of the opportunity 



1 Quoted from notes written on the spot. 



2 Quart. Journ. Geol. Soc. vol. xlix. (1893) p. 200. 



3 Ibid. p. 210. 



