304 SKY. -^GEOLOGY. RED SANDSTONE. 



the opposite mainland are 'separated by the body of sand- 

 stone which lies to the south of Island Reoch and is 

 succeeded by the gneiss of Glen Elg. Its character resem- 

 bles that of the southern parts of Sleat, consisting of 

 laminar felspar and chlorite schist, connected with mica- 

 ceous schist and passing gradually into graywacke. 

 " Resuming this series as it is displayed along the sea 

 line, the alternations of schist and quartz rock are found to 

 be succeeded by great tracts of the quartz rock alone, here, 

 as before, generally very compact, .though occasionally 

 acquiring an arenaceous structure. It is at first of a lead 

 blue, then grey, brown, reddish, or mottled, under some 

 of which modifications it might with equal propriety be 

 called an indurated sandstone. In composition it is subject 

 to another material variation ; the quartz becoming mixed 

 with felspar of the same colour, so intimately, that the 

 mixture can scarcely be detected but by the weathering 

 of the surface, which becomes harsh and rough; the one 

 substance decaying while the other remains. In some 

 cases the proportion of felspar is so great that the quartz 

 nearly disappears, the rock when weathered being easily 

 recognised by the whiteness of its surface, and, though 

 less easily, by its recent fracture. I have called it felspar 

 from the result of its decomposition ; it may belong per- 

 haps to a class of substances (the compact felspars) which 

 mineralogists have not yet considered with the attention 

 they merit. 



With no material change, the same substances continue 

 all round this promontory by the Cailleach stone and 

 Loch na Best to Moil Castle ; and in this direction, nearly 

 the whole series is traced transversely from its commence- 

 ment to its termination.* For a long space the predominant 

 dip is towards the south-east, but the beds occasionally 



* Plate XIV. fig. 3. This section will convey a general idea of the 

 positions of the strata, sufficient f r the purpose of elucidating the changes 

 they undergo. 



