322 Reviews — Geological Surmy of Scotland. 



round or flat-topped. Beinn Bharrain (2,345 feet) and Beinn 

 Bhreac (2,333 feet) are the highest points of a continuous ridge ; 

 Meall-nan-Damh (1,870 feet) and Meall Mor (1,602 feet) are 

 isolated conical hills. The streams from these drain west of 

 Loch-na- Davie and north down Glen Catacol. 



From the masses of Caisteal Abhail (2,817 feet) and Cir Mhor 

 (2,618 feet) diverge ridges that embrace the glens of Sannox and 

 North Sannox, which drain eastwards, and that of Kosie, which drains 

 southwards, into Brodick Bay. More than twelve peaks in these 

 high ridges exceed 2,000 feet. Goatfell, the highest summit in the 

 island, which attains to 2,866 feet, is on a continuous range of high 

 ground over 2,000 feet in elevation, which runs in a curved line 

 from Cioch-na h-Oighe (2,168 feet), round the head of White 

 Water, past Goatfell, some half-mile down its southern spur. 

 The fine panoramic photographic view from the top of Goatfell, 

 looking north, forms the frontispiece (plate i) of this memoir. 

 It shows admirably the continuous high ridge running in a curved 

 line, on which the so-called north top of Goatfell stands up and 

 forms a prominent peak. For three-quarters of this distance the 

 ridge is nearly everywhere over 2,500 feet, and only falls slightly 

 below that height at one or two points. A ridge which bounds the 

 White Water on the north runs eastward to Am Binnein (2,172 feet). 

 Holy Island is steep and rugged, and rises to above 1,000 feet in 

 height. 



Only an outline is attempted of the very complicated geology of 

 the northern part of the Isle of Arrau, which forms the bulk of th©^ 

 land in this Sheet, fuller details being reserved for a complete 

 memoir on the island. The principal additions to our knowledge of 

 the geology of Arran made during the progress of the Survey are : — 

 The discovery of the former extension of Cretaceous, Liassic, and 

 Rhaetic formations in the island from the presence of fragments of 

 these rocks enclosed in a Tertiary volcanic vent. The definite 

 determination of the Triassic age of the sandstones, conglomerates, 

 and marls of the southern part of Arran, and their unconform ability 

 to the Carboniferous rocks. The restriction of the Carboniferous 

 formation to an extremely narrow compass in the island, a much 

 broken and faulted strip which does not extend to the west coast, 

 and the discovery in it of strata of Coal-measure age. The discovery 

 of beds of probably Arenig age in North Glen Sannox in the form 

 of black schists, cherts, and grits, associated with old lavas and 

 volcanic tuffs similar to those occurring near Ballantrae in Ayrshire. 

 The discovery of no less than six different sets of volcanic rocks in 

 addition to that formerly known as occurring in the lower part of 

 the Carboniferous formation. Of these newly discovered volcanic 

 series one is probably of Arenig age, two belong to the Old Red 

 Sandstone period, two are of Carboniferous age, and the newest, 

 which is a huge volcanic vent, is probably of Tertiary age. The 

 age and character of the numerous intrusive rocks, both acid and 

 basic, have also been definitely fixed, and their distribution more 

 accurately determined. While the majority of the intrusive rocks 



