388 Mr Smith on the Changes of the Level of the Sea. 



of the coast, another table-land would be formed exactly re- 

 sembling, but a hundred feet above, the former. 



In the basin of the Forth, beds of razor-fish {solen\ and 

 bones of the seal, have been found at the height of ninety feet.* 

 At that of seventy feet, marine remains have been found on 

 the banks of Loch Lomond, t on the Yorkshire coast, J in 

 Devonshire, || and in the Island of Skye.§ I have found them 

 in several localities in the basin of the Clyde, at the height of 

 from seventy feet to the present high- water mark. 



At an elevation of about forty feet there has been observed 

 on many parts of our coasts a series of raised beaches and ter- 

 races, which, by their magnitude, indicate the prodigious length 

 of time at which the sea level must have been stationary at this 

 height; and if we may judge of its duration from the relative 

 size of the ancient terraces with those now forming, it must have 

 exceeded the recent period of which two thousand years is but 

 a part, by an immense amount ; but this is but one of the 

 epochs in the history of this formation ; between the great ter- 

 race and the sea several subordinate ones and beaches have 

 been observed, each of them marking long continued periods 

 of repose, whilst a sudden deepening, two or three fathoms be- 

 low the low-water mark, is probably caused by another line of 

 terraces now covered by the sea. 



The great terrace, the base of which seems very generally 

 to be between 30 and 40 feet above the sea, forms a marked 

 feature in the scenery of the west of Scotland, in those parts 

 where the violence of the Atlantic has not swept away the 

 plateau of marine alluvia which, in the less exposed situations, 

 is always interposed between it and the sea. 



The northern part of the county of Ayr, which is composed 

 of a coarse red sandstone or conglomerate, has been worn by 

 the former action of the sea into a magnificent range of cliffs, 

 in some places rising to the height of 300 feet ; the two islands 

 of Greater and Lesser C umbra, lie opposite to it, and have cor- 

 responding terraces. The former of these islands is composed 



* Wern. Mem. vol. v. p. 572. t Letter from Mr Buchanan of Arden. 



;|; By Mr Witham of Lartington. Phillip's Geol. of Yorkshire. 



II Geol. Soc. Proc. Dec. 14. 183G. 



§ M'Culloch's Western Islands, vol. i. p. 293. 



