Western Isles of Scotland. 105 



mark) and rise along the dip slope of the lava bed, until it is 

 perhaps 20 feet higher than when it started on this bed. "When, 

 however, it reaches an altitude of 120 or 125 feet it invariably breaks 

 through the strong bed and begins again at a lower level. At Iludh' 

 a Chaoil, where the lavas lie approximately horizontal, a magnificent 

 level platform with cliffs nearly 300 feet high is developed at a height 

 of 120 to 125 feet above high-water mark of spring tides. The 

 platform is here and in other places along this coast nearly a quarter 

 of a mile wide, and it is impossible to confound it with the ledges 

 produced by the irregular weathering of the basalts. The persistence 

 of its general level for the distance of 5 miles, throughout which it 

 is here continuously developed, places its marine origin beyond doubt. 

 Opposite a hollow in the preglacial cliff east of Rudh' a Chaoil the 

 surface of the platform has a distinctly ice-moulded appearance. 



The southern shores of Calgary Bay show only some very 

 doubtful remnants of the preglacial beach, but on its northern side 

 the platform resumes the magnificent development exhibited along the 

 coast to the south, and this it maintains round the coast of Mornish to 

 the north as far as the Caliach Point. It shows the same tendency 

 to conform in level to the upper surface of strong beds, but, as before, 

 abandons these beds when they depart too much from its normal 

 level. In one or two places its surface has an appearance of ice- 

 moulding. A measurement of height made about one mile south of 

 the Caliach Point gave 115 feet as approximately the normal level in 

 this vicinity, but the inner angle rises in places to 120 feet and sinks 

 in others to 105 feet. Another estimate at the he;id of Calgary Bay 

 gave 1 10 feet as about the normal, while portions of the platform are 

 as low as 95 feet and others rise to 115 feet. 



South of Loch na Iveal the Mesozoic rocks of Gribun afford no 

 certain traces of the preglacial beach, but at the foot of the 

 magnificent escarpment known as The Wilderness, to the west 

 of Ardmeanach, well-marked remnants can be seen. It is probable 

 that along this coast considerably more of the platform is preserved 

 than appears to view, for the whole is much obscured by scree and 

 landslips descending from the immense cliffs above. As we pass 

 south along the coast from the farm of Balmeanach certain obscure 

 traces are seen at Coireachan Gorma, but the first undoubted remnant 

 occurs at Stac Glas Bun an Uisge just to the north of the river. 

 Half a mile further south, at Rudha nan Goirteanan, it is, however, 

 much finer, being cut in the schistose grits of the Moine Series. The 

 platform is here much obscured by material from the cliffs above, but 

 the section afforded hj a geo enables it to be traced beneath the scree 

 almost into its inner angle. Measurements showed the highest 

 portion seen to lie at a height of 98 feet. The inner angle is probably 

 a few feet higher. The cliff is composed of the same schists as the 

 platform, and appears where seen to be somewhat rounded and 

 moulded. The great cliff above from which the scree descends is not 

 the cliff of the raised beach but the escarpment of the Tertiary lavas. 

 The surface of the preglacial platform is ice-moulded. It probably 

 extends continuously from here to Uamh nan Caiman. At lludha na 

 h'Uamha there is a volcanic neck with associated columnar basalts. 



