428 ON A SUBMARINE FOREST IN THE FRITH OF TAY. 



■ 



considerably lower, would be influenced by the change ; for 

 the water even in such would be squeezed out, in conse- 

 quence of the pressure of all the matter of the strata above 

 the low water-mark, exerted during every ebb, in the expul- 

 sion of the water at the lowest level, thus permitting the sub- 

 sidence of the strata to take place even to the lowest beds of 

 the morass. 



In consequence of this drainage, produced by the ebbing of 

 the tide on those marshes, the original barriers of which have 

 been destroyed, there is no difficulty in accounting for the de- 

 pression of the surface of a marsh many feet lower than its ori- 

 ginal level, nor in explaining the fact that Neptune now tri- 

 umphs where Sylvanus reigned, and that the sprightly Nereids 

 now occupy the dwellings of their sister Naids. 



The same explanation, now offered to account for the sub- 

 marine forest of the Tay, seems equally applicable to those of 

 Mount's Bay, Lincolnshire, and Orkney. It is warranted by 

 the effects which we have observed to have taken place in differ- 

 ent districts of Scotland, from the artificial drainage of marshes 

 which had formerly been lakes, and which were in a condition 

 of surface fit for the growth both of willows and alders. In some 

 cases, where the outlet of the marsh has been lowered perhaps 

 ten feet, and a ditch at this new level opened through the mid- 

 dle of the ground, an expectation has been formed that the ori- 

 ginal surface would be drained of all its moisture, and brought 

 into an arable condition. A season, however, has scarcely elap- 

 sed, before this deep ditch has become shallow, not by the silting 

 up of the bottom, but by the subsidence of the neighbouring 

 matter, in consequence of the abstraction of the water ; and 

 the ground which was expected to become fit for yielding crops 

 of grain, has returned to a condition better suited to the growth 



of 



