120 



east side of the dike, continuously without a change of direction. 

 There is no mistaking the rocks, both the greenstone and slate are 

 perfectly well marked; a portion of the former, traversed by the 

 veins, has distinct acicular crystals of white felspar, and that con- 

 centric structure so peculiar to this rock. The state is quite 

 homogeneous a dark blue hard quartzite, in some specimens resem- 

 bling Lydian stone but the alteration from its ordinary state is not 

 remarkable. The principal granite vein is several inches (six to 

 eight) wide, and is traceable in the greenstone through a space of 

 fifteen or twenty yards ; and runs right on into the slate. Several 

 smaller veins ramify through the greenstone, dividing and then 

 uniting again. These have the structure so well described in the 

 above extract. We conclude that the slate was first injected by the 

 greenstone dike; and that the irruption of the granite, at a sub- 

 sequent period, pierced through both of these rocks. The case is 

 very interesting, being the only one in Arran, that we know of, in 

 which greenstone is proved to have been erupted anterior to the 

 injection of the granite amid the strata of slate. 



81. We recommend the geologist, who is not deterred by the 

 prospect of "a pretty stiff pull," to mount at once by the southern 

 shoulder of Groatfell, avoiding the common pathway, already pointed 

 out, which presents much less to interest him. He will thus have 

 an opportunity of examining those huge natural ramparts of granite 

 blocks, piled mass on mass to a great height, like the Cyclopean walls 

 of Tadmor or Heliopolis, and of studying the structure of a granite 

 mountain, the varieties of the rock, and its peculiar style of decom- 

 position. We especially recommend this course, if he has not 

 accompanied us on our First Excursion. 



We have now reached the south summit of Goatfell, the highest 

 point in the island, elevated 2,875 feet above half-tide level. The 

 north summit is 247 feet lower. There is not, perhaps, in Scotland, 

 another mountain peak which looks abroad upon a scene combining 

 the same variety of grand features. Many afford wider and finer 

 mountain views ; here the eye ranges over a vast extent of broken 

 coast, the whole expanse of the noble frith, and its many narrow 

 branches winding far in amid mountain solitudes. How grand from 

 this commanding height are the surrounding peaks and rugged 

 ridges, and the profound dividing glens! what lovely pictures in 

 their glassy frames are these sister islands ! how stirring the rapid 

 movements of life all day on the inner frith ! what a world of human 

 interest in that great ocean steamer starting on her outward voyage ! 

 The " sweep of the circling horizon" embraces a magnificent amphi- 



