422 ON A SUBMARINE FOREST IN THE FRITH OF TAY. 



tions of the tide? Every cavity, in this climate, situate at a 

 lower level than that of the sea, is invariably filled with water, 

 and in a condition hostile to the growth of trees, until its sur- 

 face has been elevated, by the washing in of mud, or the 

 growth of peat, to a position at least equal to the ordinary 

 rise of the tide. Since these trees could not, therefore, have 

 grown in an inland valley so far below the rise of the tide, 

 even where the sea was excluded, we must draw the conclu- 

 sion, that the surface on which these trees grew, was, at the 

 period of their growth, at least ten feet higher, in relation to 

 the sea, than at present ; and to account for this remarkable 

 change, we must adopt one of the following suppositions : — 

 Either that the sea has risen ten feet, and overflowed that sur- 

 face which was formei'ly beyond its reach ; or, that the ground 

 supporting these trees has sunk to the same extent. 



The fii'st of these suppositions, viz. A permanent rising of 

 the sea, has not been resorted to by any of those writers whom 

 we have had an opportunity of consulting. Indeed it is con- 

 trai-y to those known laws which regulate the movements of 

 the ocean, and receives no support from any circumstances 

 which have been observed on the maritime shores of this 

 country. 



If, then, we abandon the idea that the sea has gained an 

 elevation of its level, and adopt the other supposition, viz. 

 That the peat-bed has sunk, so as now to be ten feet lower 

 than when the trees grew upon its surface, we advance a step 

 nearer the object at which we aim. It still remains, however, 

 to be determined, what those causes were, which operated in 

 depressing the surface of this bed, and enabling the waves to 

 pass over that soil which was formerly so much beyond their 

 influence, as to be fit for the support of the hazel and the birch 

 tree. 



The 



