Vol. 60.] ANNIVEBSABY ADDRESS. XC1X 



cases they can be seen to pass below the limits of the lowest tides, 

 and thus to be constantly in part submerged. The trees and the 

 freshwater plants must have lived above the reach of the sea, 

 so that they now lie 20 feet or more below the level at which 

 they originally grew : and the conclusion has been drawn that they 

 mark a general subsidence of these islands, to the amount of at least 

 20 feet, at a comparatively recent date. 



I am inclined to believe that this conclusion has been rather too 

 sweepingly drawn. That some of the submerged forests may be 

 satisfactorily accounted for without any change in the level of the 

 land or of the sea, was urgently enforced more than eighty years ago 

 by John Fleming, in reference to the examples first brought to notice 

 by him in the estuaries of the Tay and the Forth. 1 It will be 

 readily understood that, in the later stages of the Glacial Period, 

 when much detritus was swept off the land into the sea, the 

 conditions would probably be especially favourable for the formation 

 of alluvial bars along our coasts, such as are now in course of 

 accumulation for hundreds of miles on the southern coast of Iceland, 

 where some of the features of that period may still be said to 

 linger. Behind these barriers lagoons would be formed, which in 

 course of time might become marshes, and eventually peaty flats, 

 supporting a growth of trees. But when the supply of sediment 

 failed, and the sea, instead of heaping up the bars, began to breach 

 them, the level of the bogs would sink by the escape of their water 

 to the beach, and the tide at high-water would overflow and kill off 

 the forests. Occasionally, owing to the action of underground 

 drainage, the seaward margins of forest-covered peaty flats may 

 have been detached from the main body and launched downward on 

 the beach, even beneath low-water mark. 



Prof. Suess invokes changes of this nature to account for the 

 phenomena of the sunk forests around the borders of the North Sea, 

 which he thinks do not indicate any change of level of the land. 

 He believes these changes to be of local origin, due sometimes to 

 downward slipping of the peat-mosses, sometimes to invasion of the 

 sea during violent storms, or where natural or artificial barriers 

 have been broken down, sometimes, as in the Baltic, to variation> 

 of sea-level due to meteorological causes. 



1 His account of the submerged forest on the south side of the Firth of Tay 

 is contained in the 9th volume (1822) of the Trans. Boy. Soc. Edin., p. 419 ; 

 and that of the similar accumulation in Largo Bay, on the northern shore 

 of the Firth of Forth, in the Quarterly Journal of Science, Literature, & Art. 

 n. s. vol. vii (1630) p. 21. 



