136 Dr. Mac Culloch's observations 



north-western coast of Scotland and in the islands connected with it. 

 The interval between these two principal masses of sandstone may 

 be said, in a general way, to extend from near the Mull of Cantyre 

 to Kintail, and the predominant rocks throughout this space are 

 gneiss, micaceous schist, quartz rock, and a variety of analogous 

 substances which it would be out of place to enumerate here. 



It is in this interval that the scattered fragments of the sandstone 

 strata are to be occasionally found, sometimes like that near the foot 

 of Cruachan, connected only with the more ancient rocks, in other 

 places associated with and covered by a variety of rocks more or less 

 appertaining to the trap family, or to the porphyritic rocks which 

 accompany them. It would lead to a length of description unfit 

 for this paper to describe the places where they are to be seen, but 

 I may mention two which are remarkable on account of the narrow 

 space which the sandstone occupies^ still more limited than even in 

 the spot which has led to this discussion. These are the island of 

 Seil, and Inish capel, in the latter of which their total extent only 

 amounts to a very few yards. It is remarkable that in all these cases, 

 as far at least as I have examined them, their dip is toward the west, 

 however limited this may be, and that this is also the dip of the 

 leading masses both at the southern side of the interruption above 

 quoted and at its northern extremity where the same strata are 

 found occupying parts of many of the islands, and extending for a 

 considerable space between Kintail and the Ru Storr in Assynt. 



The uniformity of their dip proves that these independent masses 

 have not been separated by any disturbance from below, and w T e 

 have therefore to chuse only between two explanations ; either that 

 they had been originally independent deposits, or that they had 

 formed one mass subsequently disjoined either by the operations of 

 water or of other destroying forces acting on the surface, or else 



