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XXXIII. On the Serpentinite of the Lizard — its Original Rock- 

 condition, Methylotic Phenomena, and Structural Simulations 

 of Organisms. By Professors William King, D.Sc. §c, 

 and T. H. Rowney, Ph.D. 8fc* 

 [Plate II.] 



Its Original Rock-condition. 



DE LA BE CHE, referring to the " apparent passage" of 

 hornblende slate into serpentine rock at Poltreath and 

 other places, remarks that the phenomenon is " somewhat em- 

 barrassing, inasmuch as there is reason to conclude, from the 

 grauwacke conglomerate at the Nare # Point in the north part 

 of the Lizard district, that hornblende slates were in existence, 

 forming a surface from which large portions were abraded by 

 the action of water, while the serpentine and diallage rocks of 

 the Lizard were not formed; for rounded pieces of the hornblende 

 slate, though rare, are found in the conglomerate, while no 

 trace has yet been discovered of either serpentine or diallage 

 rock, though the latter especially is of great hardness, and 

 therefore quite as likely as the hornblende rock to resist com- 

 minution into fine sand, and the two former are nearer to the 

 conglomerate than the latter." He also observes, " in contra- 

 diction to this apparent passage, we find a mass of serpentine 

 amid the hornblende slate between Dranna Point and Port- 

 halla, on the north of the principal mass of serpentine, 

 which has every appearance of having been thrust up among 

 the hornblende slate, twisting and contorting the lamina; ad- 

 joining it in directions which we should consider consistent 

 with the passage of the serpentine in a state of igneous fusion 

 through them. As a whole, however, the hornblende slate and 

 rock seem to have formed a basin into which the serpentine 

 and diallage rock have been poured in a state of fusion" |. 



From observations which one of us made during a few days' 

 examination of the Lizard in the summer of 1873, kindly aided 

 by Mr. W. V. Symons, manager of the Poltesco Marble Works, 

 we are ready to admit that the serpentine rock of that district 

 occurs both as interstratified and intersecting masses. 



On the east side of Poltesco Cove there is a hard heavy rock 

 in well-marked thick beds, composed of darkish green and 

 greyish alternating laminse lying strictly parallel with the 

 planes of bedding, and porphyritic through the presence of 

 innumerable disformed crystals of a kind hereafter to be de- 

 scribed. The green laminae consist of impure serpentine, ap- 

 parently highly aluminous ; and the grey ones are seemingly an 



* Coniniimicated by the Authors. 



t Geological Report on Cornwall, Devon, and West Somersetshire, 

 p. 30 (1839). 



