104 R. Chambers, Esq., on the 



cut ; that is to say, a space composed of a vertical cliff rising 

 from a level platform. This cliff is in many places forty feet 

 high ; but in some, is not less than a hundred ; while the plat- 

 form is seldom less than a hundred feet broad, thus affording 

 sheltered situations for hundreds of villas to the wealthy in- 

 habitants of Glasgow. Where composed of sandstone, the 

 cliff is apt to be perforated in pretty deep caves, many of 

 which are memorable in the history of the smuggling trade. 

 In some places in Arran, where the cliff is of this rock, huge 

 slabs are left prominent above, hanging over like a pent-house. 

 On other parts of the coast, where mica slate prevails, a harder 

 mass of that formation, or a mass of upthrown trap, will be 

 found starting up in some fantastic form from the platform ; 

 and occasionally there is a crowd of such objects. 



The very great amount of attrition borne witness to by this 

 terrace, in comparison with that which can be traced on the 

 present coast line, shows that it must have been the meeting- 

 point of sea and land during a much longer space of time than 

 the present beach. We know on tolerably good grounds that 

 the existing relative level of sea and land has been unchanged 

 during the historical era, or for not much less than two 

 thousand years. It follows that the space of time during 

 which this terrace was the sea beach, must be some large 

 multiple of two thousand years, if not of something consider- 

 ably more. It seems as likely to have been the beach for ten 

 thousand years as the present is for the fifth of that period. 



The immediate object of this paper is to exhibit proof that 

 the formation of this terrace is not an event immediately prior 

 to the assumption of the present line of relative level between 

 sea and land, but one of some antiquity in the post-tertiary epoch. 



In passing along the north-west coast of Arran, from Loch 

 Ranza southwards, we have the ancient sea- cliff rising like a 

 wall of from fifty to a hundred feet high all the way, some- 

 times bare as when it was left by the dash of the sea, in other 

 places feathered with fern, and birch, and the mountain ash ; 

 in all places striking and picturesque. In his progress, the 

 eye of the observer is suddenly arrested by the appearance of 

 something like the boulder clay resting on the face of the cliff. 

 The mystery begins to clear when he finds that he is close to the 

 opening of a Highland valley called Glen Iorsa, the mouth of 



