SOA. GEOLOGY. 421 



The whole island is formed of that alternation of red 

 sandstone and gray wacke schist which has already been suf- 

 ficiently described in speaking of Sky. Although subject 

 to many local disturbances, the general bearing and dip 

 of the strata are regular throughout the island. They are 

 also entirely conformable to those of the strata in Sky, 

 the direction being towards the north-east and the dip 

 north-westerly; the angle of inclination appearing to lie 

 between twenty and thirty degrees. 



There is one remarkable feature in the structure of this 

 sandstone which I did not perceive in Sky : it occurs 

 however in Rasay also, although it was not there men- 

 tioned. The beds are split by fissures which divide them 

 into prismatic and cuboidal masses, their angles becoming 

 at length rounded in such a manner, that when viewed in 

 particular directions they have an aspect exactly resem- 

 bling that of certain granites. The flexures which inter- 

 fere with the exact inclination of the beds are frequent, 

 although commonly trifling in extent; but it may be 

 remarked generally, that there is no where in this island 

 the same solid continuity of rock that occurs in the first 

 and largest portion of the red sandstone of Sky. 



There is nothing particular to remark respecting the 

 composition of this rock. Its general features are those 

 of a red argillaceous sandstone, sometimes inclining to 

 brown or - grey, now and then highly indurated and con- 

 taining distinct grains of felspar. Sandstone schist and 

 conglomerates, commonly of a fine structure, also occur 

 in it ; and the argillaceous schist has often that fine tex- 

 ture which, as in Sky, would cause it, in a mineralogical 

 view, to be ranked with clay slate. 



Like the opposite shore, it is traversed by trap veins, 

 which however present no phenomena worthy of being 

 recorded. 





