b GEOLOGY OF ARRAK. 



Head, 457 ; West Bennan, 523 ; highest point near the south- 

 west coast on the muir of Corricravie, Cnoc Reamhar, 737 

 feet. The interior heights separate the various glens and 

 river-courses, whose origins lie near the central line or 

 axis of the island, but often interlace with one another, 

 so that a stream issuing westward has its source nearer 

 the east coast than the west, and vice versa. The views 

 of the northern mountains from these uplands are very 

 grand, especially when they are seen in the early sum- 

 mer twilight, their dark jagged peaks projected against 

 a background of sky, still lit up with brilliant hues from the 

 departed sun. The terrace border, so conspicuous around 

 the estuary of the Clyde, is marked in the southern section 

 of the island with less continuity than round the northern 

 part, owing to the nature of the rocks, and their advance in 

 many places upon the sea-line in mural precipices. Still, 

 however, it is sufficiently distinct in many parts, as about 

 Corriegills, Whiting Bay, portions of the south coast, and 

 towards King's Cove on the west, where its salient and re- 

 entrant angles, in their bold points and noble sweeps, enclose 

 some of the finest scenes of quiet beauty to be met with in 

 Scotland. 



General Outline of the Structure. 



4. The remarkable geological structure of Arran, and the 

 striking physical features which give such a charm to its 

 scenery, are alike due to a single peculiarity the abnormal 

 position of its granite nucleus. Granite usually forms a 

 middle dominant ridge, or mineral axis, to which the lateral 

 ridges on either side are subordinate and equally related, as 

 in the annexed ideal section, fig. 2, where a is the granite 

 axis ; bb, old slates corresponding on opposite sides ; cc, 

 younger slates, and so on. In Arran, on the other hand, 

 the granite does not form a mineral axis, but has been 

 protruded close to the outer border of the two upper slates, so 

 as almost to come in contact on the E. side with the newer 



