182 Mr, Griffith on the Syenite Veins which traverse Mica Slate 



The mass of the upper and lower veins is composed of dark green, crystallized hornblende, 

 brownish red felspar, and occasionally quartz. The rock may be said to be finely grained. The 

 hornblende is crystallized in long six-sided prisms ; and the felspar exhibits its usual rhomboidal 

 structure, but no distinct crystals. It is to be observed, that the hornblende is more abundant 

 near the upper and lower parts of the vein than in the centre, and a regular transition between 

 syenite and greenstone, is observable in the mass of the vein. This variation is most remarkable 

 in the thin centre vein, which contains much black hornblende, and some black quartz. This vein 

 is also peculiar from its presenting oval-shaped masses, from two to ten inches in diameter, and 

 about one third as thick, composed of crystalline greenstone, enveloped in a congeries of plates of 

 pinchbeck brown mica. In one or two places, I observed a tendency to similar structure in the 

 upper vein. 



When seen at a distance, the upper and lower veins present a rudely colum- 

 nar structure, the prisms being at right angles to the inclination of the veins. 



Syenite, similar in every respect to the upper and low^er veins, occurs near 

 to the summit of Torr Eskert Hill, about half a mile to the south of Goodland 

 Cliff. (See wood-cut. No. 1. p. 179.) 



Owing to the covering of diluvial matter, the surface soil, and herbage, 

 it is impossible to trace the syenite veins of the coast to this point; but in lay- 

 ing down the line of the veins of Goodland Cliff on the Ordnance Map, and 

 making due allowance for their average inclination, and the elevation of the 

 hill, I entertain no doubt that the syenite of Torr Eskert, is a prolongation of 

 one of the veins of the cliff. 



Torr Eskert Hill is about 970 feet above the level of the sea. At a distance, 

 it presents a bold escarpment to the north, and in this respect exhibits a cha- 

 racter quite distinct from the comparatively tame outline and green acclivities 

 of the neighbouring chalk hills. Its summit is composed of strata of compact 

 chalk, dipping east, at an angle of 5° from the horizon ; and is divided into 

 three perpendicular escarpments, having sloping terraces between them. The 

 vertical portion of the two upper escarpments, may each be about ten feet in 

 height ; and that of the lowest is also ten feet, but its upper half is composed 

 of indurated chalk, and the lower of syenite, a part of which is rudely co- 

 lumnar. 



This syenite cannot, either in external aspect, or in internal structure, be 

 distinguished from that of the cliff, and the same transition into syenitic 

 greenstone is observable. Having made an excavation and cleared away 

 part of the surface soil and grass, both above and beneath the syenite, I ob- 

 tained the following section. Commencing from the top; compact chalk, 

 five feet*; syenite, five feet; an irregular bed of chalk, from nine inches to one 



* The grain of this chalk is closer and more compact than that of the chalk forming the summit 

 of Torr Eskert. 



