various parts of Scotland. 419 



high faces of StafFa sink into insignificance on a comparison with 

 the enormous elevation and dimensions of Ailsa. With that eleva- 

 tion is combined an air of grandeur, arising from the simplicity of 

 their aspect, which the pencil and pen are equally incapable of des- 

 cribing. To the lover of picturesque beauty, they possess a requi- 

 site^ of which the want is perpetually felt in contemplating the 

 basaltic columns of Staffa, or Egg. This is their gray colour, 

 catching the most varied lights and reflections, when the iron cliffs 

 of basalt are confounded in one indiscriminate gloom. He is an 

 incurious geologist, or a feeble admirer of fine nature, who is con- 

 tent to pass Ailsa unseen. 



This rock is traversed in various parts by large veins of green- 

 stone or basalt. Among these I observed one which was horizon- 

 tal, but the greater number are vertical, and of large dimensions : 

 these lie on the west side. There is no apparent alteration in the 

 rock at the points of contact. The whole of this island consists of 

 one substance, in which slight differences of appearance here and 

 there occur, but are unv/orthy of particular notice, and scarcely suf- 

 ficient to constitute a variety. Its basis is an even and small grained 

 mixture of white felspar, and transparent quartz, in which the 

 former appears to predominate. This mixture constitutes more 

 than three-fourths of the stone, and is mottled by minute and in- 

 distinct stains of a black colour, which through the magnifying glass 

 are seen to consist of small grains of hornblende. These appear as 

 if diluted through the stone, and arising from a common centre; and 

 as they vary in proportion to the other constituents, so the rock 

 assumes various shades of colour, from a whitish to a blackish gray, 

 but the lighter varieties predominate. 



The stone which I have described may safely be called a syenite, 

 as it accords with Werner's definition of that compouud rock, and 



3 G 2 



