12 Dr. Mac Culloch's Account of Guernsey^ 



The hornblende in some places predominates so as to give a sort of 

 hornblende porphyry, and in others, every other ingredient is ex- 

 cluded, and a hornblende rock alone remains. I observed some spe- 

 cimens, traversed by a derivative rock of the same composition, inter- 

 spersed with minute grains of pyrites ; the only trace of the kind I 

 perceived in this island. 



This stone is very hard and sonorous, and admirably adapted for 

 building, as it easily breaks into squared masses before the hammer. 

 It is more particularly fitted for paving, from its extreme hardness 

 and toughness; and for that purpose it is exported in large quantities 

 to London and to Portsmouth, by the name of Guernsey stone, or St. 

 Sampson's stone. 



A similar succession of rocks occupies the remainder of the coast to 

 the town. 



Such, as far I had opportunities of remarking, is the mineralogical 

 structure of this island. The discovery of lime was much desired by 

 the inhabitants, but there is no appearance of limestone. 



Although the principal rocks are of a metalliferous nature, no 

 metallic traces have at any time been observed. 



It has been a common belief in England that emery was a product 

 of this island, but of this I could neither obtain physical nor historical 

 evidence. 



The soil which is the produce of the decomposed gneiss is abun- 

 dantly fertile, the ground being well watered, in a climate exposed to 

 the first arrival of the Atlantic clouds. Springs and rivulets are 

 therefore plentiful, and as is usually the case in siliceous countries, 

 the waters are remarkably pure and free from saline impregnations. 



Of Herm and Jedhout which are detached prolongations of the 

 same rocks, nothing can be said which would not be a repetition of 

 what I have remarked concerning Guernsey. The inaccessible ridge 



