1857.] . GEIKIE SKYE. 13 



bedded in the igneous rock, but rather look as if lying upon it or 

 sunk into it. The syenite can be seen at different points protruding 

 among these detached masses of limestone, but in no instance did I 

 observe it enveloping and overlying them. It is, moreover, equally 

 void of all fragments of altered limestone or shale, such as one sees 

 caught up in many greenstones, especially along the sides of dykes ; 

 nor, save in one or two doubtful instances, did I detect it sending 

 out veins into the adjacent rock. I may remark, in passing, that 

 these isolated masses of limestone, as well as the great body of that 

 rock for some distance from the syenite, are highly altered, assuming, 

 in fact, the aspect of a crystalline marble. To this remarkable meta- 

 morphism I shall refer more at large after the igneous rocks have 

 been described. 



The class of disrupting syenites includes, in addition to the hills 

 above described, the long irregular ridge of Beinn an Duhhaich. 

 This eminence exhibits along its northern boundary the same abrupt 

 vertical junction with the limestone that is shown on the sides of 

 the opposite hills. Its southern edge is more irregular, containing 

 many isolated masses of limestone, like those referred to on Beinn na 

 Cailleaich, while the contiguous limestone in turn contains not a few 

 protruding knobs of syenite. In short, it is a repetition on a smaller 

 scale of the great syenitic zone that girdles in the Strath Valley to 

 the north. But as its western extremity has been much wasted by 

 the waves of Loch Slapin that come surging in from the Atlantic, 

 a section has been cut across its breadth, and its contact with the 

 limestone is accordingly well displayed on both sides. The following 

 cliff-sections convey an idea of the appearances here presented. 



The South junction of Syenite and Marble on Loch Slapin (Sketch 

 No. 4, MS.). — Here the marble has a vertical dip, and a few yards 

 southwards it inclines to the south-west. The syenite is a coarse 

 granular rock, meeting the marble vertically below and bending a 

 little over above. A syenite-vein is seen extending into the marble 

 horizontally for 2 or 3 feet from the main mass of syenite. It looks 

 as if it had been squeezed into an open fissure. 



The North junction of Syenite and Marble on Loch Slapin (PL I. 

 fig. 7) represents the junction at Camus Smalaig. The marble 

 here is a pure white, almost saccharoid rock. It seems to have a 

 rude dip to the north-west, but this may be deceptive. The syenite 

 assumes a somewhat finer texture along the line of contact, and at 

 the lower part of the visible junction is charged with green serpen- 

 tine, which likewise discolours the contiguous marble. Neither in 

 this junction, nor in the corresponding one, half a mile south, does 

 the syenite overlie the limestone. At the southern locality it falls 

 over atop, as above stated, but the appearance is probably caused by 

 a sudden change in the strike of the line of demarcation, whereby, 

 in place of its edge, its plane is presented to view. 



The remaining masses of syenite belong, for the most part, to the 

 second or overlying class, of which Beinn Bhuidhe may be taken as 



