174 Dr. Mac Cul loch's Supplement to the 



place they continue to form high cliffs, covered in a similar man- 

 ner by trap, and extending along the coast for a considerable space 

 towards Holme. Limestone occurs together with the sandstone 

 in the interval last described, but the shore is so difficult of access 

 on account of its rocky boundary, the want of creeks or harbours 

 where a boat may land, and the general prevalence of a heavy sea, 

 that it is not possible to trace every point, nor, consequently, to 

 perceive where the changes of the strata take place j while, from 

 the mural front and excessive height of the cliffs, they are them- 

 selves absolutely inaccessible. To add to the difficulty, the lime- 

 stone when weathered puts on the grey colour and aspect of the 

 sandstone so perfectly, that it is often difficult to distinguish them, 

 when even within reach, without the assistance of a recent fracture. 



I must here premise that the whole of the strata hereafter to be 

 described, as well as those now mentioned, have a regular and even 

 dip towards the north-west, which is at a small angle, although no 

 opportunity is offered of ascertaining its quantity. In this respect they 

 are conformable, if they are not absolutely consecutive, to the Strath 

 limestone, and I may add that this dip is apparent over the interior 

 country wherever they can be seen, while at the same time it is 

 indicated generally by the gradual disappearance of the lower beds 

 on the west side of the promontory, their thickness amounting on 

 that shore to a few feet only, while on the east side it reaches to 

 many hundreds. I need scarcely say that cases of obvious disturb- 

 ance connected with the interference of trap must be excepted from 

 this general rule. 



Passing Holme the shore becomes occasionally more easy of ac- 

 cess, although the mural line of cliff continues, and here limestone 

 strata are found to have succeeded to the sandstone. These strata 

 contain spheroidal concretions similar to those which attend the 



