308 MR. J. PARKINSON ON THE ROCKS OF [May I9OO, 



character, become apparent. This is shown by the clear evidence 

 of another brecciation, somewhat earlier than that caused by the 

 granite and exhibiting certain important differences. The rather 

 interesting rocks resulting from this intrusion by a process of 

 melting and incorporation are confined almost entirely to the neigh- 

 bourhood of the headland between Greve d'Azette and St. Clement's 

 Bay. Westward of these evidences of brecciation are found again 

 everywhere, but the variations in the older rock are not marked, and 

 the invading rock differs in several particulars from the granite to 

 the east. 



For purposes of description, the coast including Greve d'Azette 

 and the western part of St. Clement's Bay will be termed the 

 Eastern District, that of Havre des Pas and St. Elizabeth's Castle 

 the Western. 



II. The Eastern District. 



The oldest rock of the coast is a diabase so closely resembling 

 the one of Sorel Point that a detailed description is unnecessary. 

 The original colourless augite is now almost entirely replaced by 

 brownish-green hornblende, with which a rather fibrous mica is 

 associated in some slides, no doubt the result of a further change. 

 The augite was later in consolidation than the felspar, producing 

 the common ophitic structure. In one section of a specimen from 

 Greve d'Azette, the replacing hornblende shows a faint striation 

 making an angle of 70° to 72° with the prismatic cleavage in 

 sections approximately parallel to the clinopinacoid, and therefore 

 probably the basal striation of the original augite. The specific 

 gravity of this specimen is 2*88. 



(1) Characters of the Earlier Acid Intrusion. 



To the westward of the Martello Tower at Pontac the cha- 

 racters of the diabase and the rocks immediately associated with it 

 are most interesting. Here, close in to the shore, can be seen the 

 partial splittiug-off and the entire isolation of a fragment, together 

 with the subsequent softening and trailing-out which it undergoes, 

 a process accompanied in greater or less degree by the absorption 

 of its substance. This is referred to as the earlier brecciation. 

 The texture of adjacent fragments varies from a fine-grained rock, 

 with its constituents barely distinguishable by the naked eye, to 

 a much coarser one in which the mottling of hornblende and 

 felspar can be at once seen. In many cases the most clearly 

 defined fragments show curved outlines with blunt projections, 

 indicating that they were in a softened state during the intrusion 

 of the more acid magma. Erequently the rock round them contains 

 more hornblende than the vein proper, and scattered through this 

 zone, which may be \ inch wide, are numerous small fine-grained 

 patches indistinguishable from the fragment. There can be no 

 doubt that these represent portions which have escaped absorption. 



