Dr. KiDD on the Mineralogy of St. David'* s, 91 



the crumbing scliistus which is here opposed to them, and that 

 consequently in process of time, as this schistus is extended across, 

 the island to the eastern shore, the island may eventually be sepa- 

 rated into two. 



The harbour of Ramsey is a small cove excavated in a mass of 

 black schist, and situated near the southern extremity of the eastern 

 front ; advancing from which towards the west, and then ascending 

 the southern beacon from its northern side, you pass over an ap- 

 parently conglomerate rock made up almost entirely of large pebble- 

 shaped masses of white quartz. From the uniformity of colour in 

 this rock, and from its general appearance, a doubt at first sight 

 arises whether it is really a mechanical conglomerate or the result 

 of a peculiar chemical conformation. 



On and near the summit of the southern beacon the rock in many 

 places resembles coarse chert, from which it passes into the state of 

 indurated clay containing small crystals of felspar and of dodeca- 

 hedral quartz, the latter in general very imperfectly defined. 



The composition of the rock forming the northern beacon is 

 felspar and hornblende, sometimes assuming nearly a homogeneous 

 appearance, and sometimes, though rarely, inclining toaporphyritic 

 structure. 



With the island of Ramsey these notes on the Mineralogy of the 

 neighbourhood of St. David's terminate, in drawing up which it 

 has been my object to avoid as much as possible the language of 

 hypothesis, and to detail the appearances which I met with in terms 

 strictly descriptive : and though I feel strongly persuaded, on 

 grounds which have not been taken up hastily, that all the rocks 

 which I have been describing are essentially allied to each other, 

 and are all of chemical and cotemporaneous origin j yet, conceiving 



M 2 



