284 Correspondence — Rev. 0. Fisher. 



of the land or rising of the sea. He thinks that the formation of a 

 bar of shingle across the mouth of an estuary would admit of the 

 surface behind it being dry, although it should be below high-water 

 mark ; and that a forest might grow there. One sees marsh land in 

 such positions, but unless there are instances of trees of the same 

 kind as those found in submerged forests now growing below high- 

 water mark, it seems doubtful if they grew there formerly. But the 

 important question is, what have been the relative movements of 

 land and sea since these forests were green? Can we correlate 

 changes of level indicated by other phenomena with such as must 

 have raised or depressed these forest lands. Mr. Godwin- Austen, in 

 his paper "On the Superficial Accumulations of the Coasts of the 

 English Channel, and the Changes they indicate," * arrives at the 

 conclusion, from marks impressed upon the hard rocky margins of 

 the Devon and Cornish coast, that there has been "a change of 

 level, which, so far as elevation is concerned, is necessarily the most 

 recent which has taken place on this section (Dartmouth), and 

 which we may estimate at eight to ten feet." A depression of that 

 amount, he remarks, "would convert the valley of the Exe into a 

 salt-water estuary, and account for the beds of Ifactra, Tellina " 

 (quae Scrobicularia) and Cardium found at Alphington." And he 

 states that this movement has been a imiform one throughout, and 

 extends over the area of the German Ocean. Now the remarkable 

 thing is that we have, in every case that I have seen, evidence of 

 such a depression wherever a submerged forest exists. The stumps 

 of the trees are always enveloped in, or covered by, a mud, full of 

 dead shells of Scrobicularia piperata, Cardium, and other estuarine 

 shells ; generally of large size. This deposit is laid bare by the 

 erosion of the waves at the present day, pari passu with the 

 uncovering of the forest itself, as the beach is thrust forward over 

 the marshes. This clay, under the name of " Buttery clay," with its 

 usual shells, extends over a great part of the fen land of this 

 neighbourhood, where they spread it over the peaty soil to give it 

 consistency. Beneath it are the remains of forest trees of large size, 

 which sometimes, as the soil sinks through the effect of drainage, 

 protrude above the surface, so that they require to be dragged out by 

 horse power; otherwise they obstruct the plough. There is a 

 detailed account of a submerged forest at Porlock Bay, by Mr. 

 Godwin-Austen, in which the points usually connected with these 

 deposits are excellently brought out. 2 



Colonel Greenwood's theory will not explain the, I believe 

 universal, presence of the Scrobicularia clay covering the old fossils ; 

 while this answers exactly to the depression since balanced by the 

 8-10 foot elevation established on other grounds by Mr. Godwin- 

 Austen. That elevation has brought the forests with their estuarine 

 envelopes to the level of present half- tide. But they have been 

 eight or ten feet lower than they are now, and consequently fully 

 " submerged." It seems to me, then, that they are justly entitled to 

 their old appellation, and that it is a mistake to suppose that they 



1 Jouin. Geol. Soc. vol. vii. p. 118. 2 Journ. Geol. Soc. vol. xxii. p. 1. 



