C PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [May I904. 



Had our littoral sunk forests been confined to a few places where 

 the topographical conditions were specially favourable for their pro- 

 duction, we may concede that they would not in themselves furnish 

 sufficient proof of a shift of level, either on the part of the land or 

 of the sea. But when we consider their widespread distribution 

 all round the margin of these islands, even on those shores where it 

 is difficult to believe that there has been any subsidence or slipping 

 downward of a land- surface owing to the draining-off of under- 

 ground water, we may well doubt whether the old belief should 

 be disturbed, that the facts, taken as a whole, prove a general 

 submergence. 



Fortunately, the evidence available on this subject allows us to 

 go a step farther. We need not be content with such debateable 

 proofs as are furnished by the sunk forests between tide-marks, for 

 land-surfaces can be adduced, which are buried beneath marine 

 accumulations under circumstances that leave no doubt as to the 

 facts of submergence. 



In the Xorth-East of Ireland, excavations at Belfast have shown 

 the existence of a bed of peat lying almost immediately upon the 

 Glacial deposits, at a depth of 27 feet below high-water mark. 

 It has a maximum thickness of 18 inches, and consists of the 

 matted remains of marsh-plants, and of hazel, alder, oak, willow, and 

 Scottish pine, together with elytra of beetles and mammalian bones. 

 It is overlain by estuarine clays, the upper portion of which, 

 containing abundant Thracia eonvexa, Scrobicularia alba, etc., is 

 believed to have been deposited in at least 5 fathoms of water, 

 and to be contemporaneous with the raised beaches of the same 

 region. 1 In this instance, mere local settlement from removal of sub- 

 soil water, or from the slipping forward of the thin seam of peat, 

 is excluded, and we are presented with evidence of an actual shift 

 of relative level, amounting probably to more than 30 feet. If this 

 land-surface was really coaeval with the neighbouring post-Glacial 

 raised beach, the original amount of submergence must have been 

 still greater, and by a subsequent emergence of the land, to the 

 extent of from 10 to 20 feet, the peat has been brought up so much 

 nearer to sea-level. 



On the east side of England, besides the sunk forests on the fore- 

 shore, important evidence of submergence has been furnished by old 

 laud-surfaces lying considerably below the level of the lowest tides. 

 At the dock-excavations of Hull a sunk forest, abounding in remains 



1 G. W. Latnplugh, &c. ' The Geology of the Country around Belfast ' Mem. 

 Geol. Surv. Irel. (1904) p. 54. 



