Mineralogy of Sky, 



25 



cecondary strata, and of an entirely new character. Their upper 

 edge is generally even, and their faces quite perpendicular, but they 

 rarely exceed 60 feet in height. They are most remarkable for the 

 very extraordinary number of the caves which are found in them, 

 and of the fissures by which they are intersected. These are rarely 

 of any great dimensions, but they are so numerous that they some- 

 times occupy nearly as much space in a given distance as the solid 

 parts of the cliffs themselves. 1 have counted twenty or thirty of them 

 in the course of a few hundred yards, the interstices having a re- 

 semblance to the ends of detached walls placed in a parallel manner. 

 They are the consequences of trap veins which have been washed 

 away, but as they present Important geological facts, I shall describe 

 them more particularly hereafter. Few of these caves have been ex- 

 plored, but one of them has acquired historic celebrity from the cir- 

 cumstance of its having been among the numerous places of temporary 

 refuge inhabited by Prince Gh&f les during his concealment. Another 

 has recently become the cause of great resort to Sky on account of 

 its stalactitic concretions, and it is popularly distinguished by the 

 name of the Spar Cave: it lies on the estate of Mr. Macalister, and 

 is too well known to require any more accurate description of its 

 locality. This cave is accessible from the cliffs above, for a short 

 time only at low water, but by means of a boat it may be visited at 

 any time in moderate weather, or with the wind off the shore. The 

 entrance is little less striking than the cave itself, and to the ad- 

 mirer of the picturesque it presents a scene even more attractive. It is . 

 formed by a fissure in the cliff, extending for a considerable way 

 and rising into high and parallel Walls on each side, its gloom being 

 partially illuminated by reflected light, and its silence scarcely dis- 

 turbed by the Vv^ash of the surf without. A narrow and obstructed 

 opening leads unexpectedly into the cave i hence for a distance of 

 Vol. in. o 



