54 ST. KILDA. GEOLOGY. 



the harbour is the fine rock Levenish, already men- 

 tioned, presenting a striking feature on approaching 

 the island. In a northerly direction is seen the very 

 picturesque island Borera with its two remarkable ac- 

 companying rocks Stack Lii and Stack an armin. It 

 appears to be about the height of St. Kilda, but is seldom 

 accessible; having no sheltered landing-place and being 

 precipitous all round. The weather did not permit me to 

 approach it. Like Soa, it maintains a proportion of sheep, 

 which few but the inhabitants of St. Kilda could either 

 place there or remove, and is also the resort of in- 

 numerable birds.* 



THE geological history of St. Kilda may be contained 

 within a very narrow space, yet is not without interest. 



The rocks all belong to the trap family, using that 

 term in its most extensive sense so as to include syenite. 

 It will be shown in the course of this work, that almost 

 all the rocks of this class which occur in the Western 

 islands, are found above the secondary strata, and are 

 therefore of comparatively recent origin : but as no 

 stratified rocks, whether primary or secondary, can be 

 discovered in St. Kilda, we have here no criterion by 

 which to judge either of their date or connexions. 



Conochan, the highest summit, is formed entirely of 

 that syenite already described as occurring in Sky, in 



* These islands are the favourite resort of gannets. No disturbance 

 ever appears sufficient to induce these, more than the other species 

 of sea fowl, to change their haunts, nor do they court uninhabited 

 places in particular. In leaving St. Kilda in an evening they are met 

 flying home in long flocks, separated widely from each other and ap- 

 parently each under its separate leader. At seventy miles from the 

 island they were all found directing their course to it. It is imagined 

 by the seamen and fishermen of this coast, that they fly out in the 

 morning to feed, even to the southern parts of Britain, and return in 

 the evening ; a circumstance not improbable, when the strength and 

 rapidity of their flight is considered. 



