oji tJie Coast of Tiree, ^c. 1 39 



It is reasonable, however, to suppose, that there must be a 

 change induced on the level of the ocean, in consequence of de- 

 tritus carried into it by rivers, as well as from the disintegra- 

 tion of neighbouring rocks and coasts. 



M. Hartsoecker endeavoured, at an early period, to prove, 

 from the analysis of the waters of the Rhine, that they con- 

 tained Y55 parts of earth ; and, generalizing on this, concluded 

 that the bed of the ocean must be elevated by the detritus of 

 mountains conveyed into it by rivers over the globe, at the rate 

 of one foot in 100 years. Mr Stevenson, without attempting to 

 fix the rate at which this elevation proceeds, has reasoned * ju- 

 diciously and clearly on the subject, and the observations lately 

 made on the coast of Africa by gentlemen sent from France for 

 that purpose, have led them also to conclude that the level of 

 the waters of the ocean is elevated by the above cause. 



It is obvious, however, that, with whatever certainty this ele- 

 vation may be carrying on, it must be very slowly, and that 

 we cannot refer the depression of submarine forests to the 

 agency of a cause operating so gradually that the same par- 

 ticles of moss would be for centuries exposed to the lash of the 

 wave, and carried away by as sure a process as can be con- 

 ducted under the laws of filtration and combination ; and there- 

 fore it is that I should be disposed to consider that the ocean 

 has not been elevated so as to inundate these lands, especially 

 at Tiree, where the sea, so far from making encroachments, is 

 daily receding, and consequently adding to the size of the island. 

 Indeed, as the displacement of many feet of water over the 

 whole depth and level of the ocean, could not fail to be rendered 

 as obvious on every coast in the universe as on one, so as to be 

 observable, especially in cities and forts, it is not to be supposed 

 that there would not be surer and more frequent proofs of the 

 agency of a cause, which operated so rapidly as to give moss no 

 time to combine with the wave, or to be carried away by the 

 tide, which regularly rolls over it. 



The depression of the land, by some cause operating upon 

 the crust of the earth, and suffering these islands to subside at 



• Philosophical Journal, April 1828. 



