Mineralogy of Sky. 172 



nearest indication of a connection between them is to be found at 

 Loch Sligachan. I have already described the limestone which oc- 

 curs on the southern shore of this inlet. On its northern side there 

 are seen a few beds of white, brown, and black sandstone, separated 

 from that limestone by the breadth of the loch only, but lying in 

 a regular order conformable to it, and doubtless connected with it 

 under the depths of the sea. These are immediately cut off by a 

 mass of trap, which extends without interruption for nearly two 

 miles along the shore, thus depriving us of all means of tracing 

 any connection between them and the next stratified rock. That 

 rock appears at Conurdan, occupying a low situation on the sea 

 shore, in a thin series of nearly horizontal but somewhat irregular 

 beds surrounded on all sides by trap. These beds consist of a 

 brown calcareo-argillace6us sandstone, similar to one of the beds 

 at Loch Sligachan, and characterized by the spheroidal concretions 

 which prevail through the greater part of the sandstone of this dis- 

 trict. After an interval of trap the same sandstone re-appears as 

 we approach Portree, but still scarcely visible except in the natural 

 sections of the shore, since the whole interior surface of the land 

 is covered by the superincumbent trap, which conceals the struc- 

 ture of this country from the most watchful eye. Here it imme- 

 diately presents a collection of beds of enormous thickness rising 

 into lofty cliffs, which, although inaccessible, may be approached 

 in favourable weather so near from the sea as to leave no doubt 

 respecting their nature. This is the hill of Camiskianevig which 

 forms the southern side of Portree harbour. 



The mass of trap which overlies these strata cuts through them 

 in the interior of the harbour, and thus forms another interruption 

 between them and the corresponding ones, which again appear with 

 similar dimensions on the northern side of the harbour. From this 



Vol. iv. z 



