100 GENERAL REMARKS ON THE 



exceeding, when jointly taken, a mile in diameter, and 

 remarkable for being the only fragment of these strata 

 to the north of Airdnamurchan. They were lately men- 

 tioned in the general comparison of the Trap islands. 

 The primary sandstone is here in one part vertical and 

 irregular, in another of a more even structure, but still 

 possessing its distinguishing characters. Above it, the 

 red secondary beds lie in a position nearly horizontal, 

 and are followed by a white calcareous sandstone, with 

 interposed beds of limestone, in all respects similar to 

 that of the coast of Morven and of the trap islands. 

 The contrast between the two classes of sandstone, both 

 in position and character, is highly interesting ; leaving no 

 more doubt of the distinction between them than if 

 gneiss, instead of red sandstone, had been the lowest 

 rock.* 



A few observations are yet required on the double posi- 

 tion occupied by this sandstone with regard to the gneiss. 

 It was remarked in the account of Mull, that the secondary 

 strata held positions respecting the primary, which were 

 in some places conformable, in others the reverse. The 

 same indifference of relative position between the two, 

 occurs in so many other situations as to be no longer 

 matter of doubt ; while, on considering the circumstances 

 under which the former were deposited, it appears to be a 

 natural result of these, and a necessary consequence of 

 the previous inclinations of the primary rocks on the surface 

 of which the deposition took place. The secondary strata 

 are however not universally characterized by a low angle 

 of position, but are found occupying almost every angle 

 from the horizontal upwards ; a circumstance which ren- 

 ders their degree of inclination as unavailing a distinction 

 as their relative position to the primary. In comparing 

 distant portions therefore, they would seem to possess a 

 want of conformity to each other; yet in tracing them 



' I'late XXXII. fig. 8. 



