ASSOCIATED IGNEOUS ROCKS OF THE AYRSHIRE COAST. 775 



a foot or two above the general level of the shore. Instances of this 

 kind occur again and again on the shore. The annexed diagram 

 (fig. 3) is a sketch of a huge block, not less than 50 feet long and 



Fig. 3. — Dioritic Rock and Serpentine, north of Lendalfoot. 



Explanation as in fig. 1. 



20 feet high, on the shore about high-water mark and some 200 

 yards north of the hamlet. Here, as may be seen, the serpentine 

 forms a sort of "skin" adherent to one side, and two or three frag- 

 ments of it are still sticking in crevices in the " dioritic" rock. It 

 would be simply repetition to describe other instances, which occur 

 almost in dozens. The junction of the serpentine and " dioritic " 

 rocks, when visible, is always perfectly clean, and conforms more or 

 less to the irregularities of the latter, whose surface has a peculiar 

 glazed aspect, and that sharp irregular jointing so characteristic of 

 a rock affected by an intrusive igneous rock. The serpentine becomes 

 rather more compact near the junction, thrusts itself in tongues into 

 fissures, and remains yet sticking in crevices. The evidence of 

 intrusion is even more clear than at the Lizard, and the two rocks 

 adhere very imperfectly the one to the other, as is usually the case 

 in Cornwall. I could not find a single instance of any thing like a 

 passage from the one to the other ; but the evidence of the intrusive 

 character of the serpentine is, to my mind, so overwhelming that I 

 cannot understand how it can ever have been doubted. 



I now proceed to describe the principal varieties of the serpentine. 

 About Lendalfoot it has a rather conchoidal fracture, with a very 

 compact dark olive-green ground-mass containing rather minute 

 and not very lustrous bronzitic crystals and thin veins of chrysotile. 

 On placing a slide beneath the microscope, we see that the structure 

 made so familiar by the Lizard specimens (vol. xxxiii. p. 916) is at 

 once evident, though in this specimen the black iron peroxide is less 

 markedly aggregated in the neighbourhood of the " strings" of doubly 



