170 Dr. Mac Culloch's Supplement to the 



without detailing the history of all the islands in the vicinity 

 which partake of and elucidate the structure of Sky, no adequate 

 conjecture can be offered respecting it. There is here no room for 

 such a description, but I hope on some future occasion to give a 

 collective view of the whole group, and thus to render the geo- 

 logical history of the principal island less incomplete than I am 

 still compelled to leave it. The connections of the western islands 

 with each other and with the main land are so intimate, and the 

 light obtained from one portion is so necessary for the elucidation 

 of others, that the separate description of any individual of the 

 group must always be imperfect. 



The account of the limestone which is found near Ord on the 

 southern shore of Loch Eishort was in the original paper imperfect, 

 as well in respect to its topography as its mineralogical description. 

 It occupies a small hill which includes the house of Ord, and is 

 singularly irregular in its position, as well with respect to its own ar- 

 rangement, as to its connection with the neighbouring rocks, among 

 which, as I have already shown, there occurs a great degree of con- 

 fusion. Notwithstanding this irregularity, a careful and close in- 

 vestigation of it will leave no doubt respecting the superiority of 

 its position to the sandstone with which it is associated, and how- 

 ever widely separated from the more regular beds on the opposed 

 shore, there is no want of indications to prove that it forms a por- 

 tion of the limestone of Strath ; its present confusion appearing, 

 like that of the neighbouring sandstone, to have arisen from some 

 common cause acting on both, to which also we may perhaps at- 

 tribute the peculiarities which its structure and composition pre- 

 sent. Its stratification is in general sufficiently apparent on the 

 great scale, although in the more detached portions often invisible, 



