6 Dr. Mac Culloch's Account of Guernsey^ 



6. A granite], consisting of quartz and felspar in equal pro- 

 portions. 



7. A similar stone with a much less proportion of felspar. 



8. No felspar at all — a fine white sandstone. 



All these varieties are evidently the produce of the disintegration 

 and reunion of more ancient granites. 



At a point on the southern shore, is a rock called La Pendante, 

 resembling a square tower of masonry, and inclined at a considerable 

 angle. It consists of portions of the strata I have been describing, 

 and appears about twenty feet high. 



Where the strata of grit cease, a vein, or an inclined stratum, of 

 black granitel, composed of hornblende and quartz, is found; which 

 appears to run straight, and in contact with them, in a N and S 

 direction across the whole island, from I'Etat to Braie. This is a 

 thick mass, but I could neither discover its dimensions, nor its points 

 of contact with the grit. It is in some places accom.panied by a fine- 

 grained sicnite of a compact nature ; and by another, much disinte- 

 grated and shot with iron. Here and there also, are fissures filled 

 with red and purple hornstone, and more rarely, fissures, or what 

 appear such, filled with sandstone-schist and mica, and often assuming 

 the appearance of micaceous schist. The grit, which is cut off by 

 this mass of granite, does not here absolutely disappear ; but various 

 strata of it and the granitel, succeed each other, till the whole ceases, 

 and is replaced by a mass of porphyry. 



Of the mass of porphyry, the remainder of the island is formed. 

 And it is the broad and perpendicular fracture of this rock, which 

 causes the picturesque appearance of the western extremity of the 

 island. 



It appears to have a great tendency to wear before the effects of 

 time. At the western point in paiticular, where it is exposed to the 



