SUBMARINE FORESTS. 31 



small scale of the effect which might be produced hy the rupture 

 of a sea barrier. At the mouth of the St John River, there is a 

 transverse ridge of rock which obstructs the entrance of the tide and 

 the exit of the river water. At low tide, the river water falls outward 

 over the ridge. At about half tide, the water within and that 

 without are on a level. At high tide, there is a strong fall of the 

 tide water inward. AVithout the barrier, the tide rises from twenty 

 to twenty-five feet ; Avithin, it raises the level of the water only about 

 four feet. Now there can be no question that, if this barrier were 

 removed, the tide would daily raise the river to a height which 

 it now attains only in times of flood, while at low tide it would 

 be laid dry to a great depth. If such a change had occurred at 

 some former period, marshes might be found to exist in places 

 which had at one time supported terrestrial plants. Against the 

 application of this explanation, however, to the submarine forests 

 of the Bay of Fundy, we have the great extent of the barrier 

 required, the absence of any existing remains of it, and the great 

 depth below high water at which the remains exist; as it is difficult 

 to suppose that the existence of any barrier, even if it wholly 

 excluded the tide, could produce dry upland at such a level. The 

 effect would rather be the production of a lake, or, at the utmost, 

 of a morass. For these reasons it can scarcely be supposed that 

 any cause of this kind can apply. It only remains to believe that 

 a subsidence has taken place over a considerable area, and to a 

 depth of about forty feet. We have no distinct evidence to show 

 whether this has been sudden or gradual, but analogy would lead 

 us to suppose that it was the latter. 



If a gradual subsidence of this kind has occurred in times 

 geologically modern, the question remains, has it ceased, or is the 

 country still subsiding, as Newfoundland and the south of Sweden 

 are supposed to be doing? There are some facts which would seem 

 to indicate that it is. In some localities portions of marsh formerly 

 reclaimed have been abandoned, and it is said that it is now more 

 difficult to maintain the dikes than formerly. We may, however, 

 readily account for all this by supposing that the mud has settled, 

 or that the tides have increased in height or have changed in their 

 direction, in consequence of the contraction of the channels by the 

 diking of new portions of marsh land. We are not therefore under 

 the necessity of arriving at the unpleasant conclusion that our fertile 

 marshes are again settling down beneath the level of the sea, or that 

 the waters of the bay are likely to overflow the upland farms. 



I should add, however, that, since the publication of the above 



