CHAP. XLVII 
THE ROCKS OF ST. KILDA 
405 
altered. They seem in places as il they have been shattered by some ex- 
plosive force, and had then been invaded by the mass that rushed into all the 
rents thus caused. This remarkable structure is still better displayed on St. 
Kilda, and is more fully described in the following account of the ^eoloerv 
of that island. 0 
iv. THE ROCKS OF ST. KILDA 
Brief allusions to St. Kilda and its rocks have already been made (pp. 
1/3, o5S). We may now enter more fully upon the consideration of its 
geological structure and history. 
hen the weather is clear there may be seen from the western head- 
lands of the Outer Hebrides a small blue cone rising above the Atlantic 
horizon at a distance of about 60 miles. As the voyager approaches this 
distant land it gradually shapes itself into a group of islets of which St. 
Kilda, the largest and only inhabited, has an extreme length of about four 
miles, a breadth of less than two miles, and a height of 1262 feet above the 
sea. Four miles to the north-east Borrera, about one square mile in extent, 
rises with precipitous sides to a height of 1000 feet. Off the north-western 
promontory of St. Kilda the huge rock of Soay, half a square mile in area, 
towers from 600 to 800 feet above the waves. Borrera has two attendant 
rocks Stack Li and Stack an Arinin — huge pyramidal masses several 
hundred feet high, and the home of thousands of gannets. St. Kilda 
possesses two less imposing islets between its north-western headland and 
Soay, and a third to the south-east known as Levenish. 
The scenery of this picturesque group affords a good indication of its 
geological structure. It displays two distinct types of topographical form. 
In Borrera the marvellous combination of spiry ridges, deep gullies and 
clefts, notched crests and splintered pinnacles, at once reminds the visitor of 
t he outlines of the Cuillin Hills of Skye. The same features are repeated on 
a less magnificent scale in Soay and along the whole of the south-western 
precipitous coast-line of St. Kilda. 
In marked contrast to these varied outlines, the eastern half of St. Kilda 
lises with a smooth green surface, varied with sheets of grey screes, up to the 
rounded summit of Conagher, the highest point in the island. If the dark 
tings of the rest of the island group remind one of the Cuillins, this eastern 
tract recalls at once the form and colour of the Bed Hills of Skye. A closer 
examination shows that in each case the topography arises from the influence 
of the very same rocks and geological structure as in that island. 
I here is, however, one aspect in which St. Kilda has no rival throughout 
the Western Isles. Its russet-coloured cone, though rising on the west side 
with gentle green slopes from the central valley, plunges on the eastern side 
hi one vast precipice from a height of 1000 feet or more into the surge at 
its base. Nowhere among the Inner Hebrides, not even on the south- 
western side of Emu, is there any such display of the capacity of the 
} oungest granite to assume the most rugged and picturesque forms. It is 
hardly possible to exaggerate the variety of outline assumed by the rock as 
