366 Geological Survey of the Island of Jersey. 



Rock (Elizabeth Castle), this alternate variegation of the red 

 felspar, with the very compact and dark-coloured greenstone, is 

 disposed nearly in horizontal layers, while the regular strata of 

 the rock stand at an angle of 70 or 80 degrees ; the red layers 

 always projecting from the weather-worn failure of those in 

 which the hornblende predominates. (See fig. D, p. 374.) 



In figures A, B, C, and from the circumstance of the red 

 veins very generally constituting the matrix of the green, and 

 the substance of the veins that traverse it, as well as that in 

 figure C ; the green portions are of various descriptions, it may 

 be questioned whether the red and green sienite are absolutely 

 coeval. 



49 is a good specimen of the very compact dark greenstone 

 just alluded to, although it was taken from a large vein between 

 Grosnez and Plemon. This last is not quite horizontal, but 

 continues about 7 feet thick, whilst it gradually rises along the 

 face of the almost vertically stratified cliffs : upwards of 3 feet 

 in depth have been decomposed and disappeared. This vein 

 divides in one place, which reduces the thickness of the two 

 parts to that of about 3 feet each, until they rejoin and pro- 

 ceed as before. The same substance frequently accompanies 

 the veins of argillaceous schist. 



40, from Elizabeth Castle, as in 39 ; which last, although 

 but an accidental stone from the beach, corresponds to 44, 

 which was taken from a vein from Portlet Bay ; it is, I believe, 

 the hardest rock in the island. 



20, shews the ultimate state of decomposition of the horn- 

 blende and felspar. 



An east and west vein of chlorite mica ; traverses the hill 

 where Fort Regent stands, 19 a. 



Felspar and Schorl. 



16 and 17, From La Motte ; not much of it. I have seen 

 specimens in which the schorl lay as minute, confusedly-scat- 

 tered and divergent crystals in the felspar. 



Felspar, Quartz and Hornblende. 



The felspar in this variety is red, and this association with 

 quartz and hornblende, forms by far the most extensive rock 



