OF THE LEVEL OF THE SEA. 



67 



consist of fine and coarse sand or clay, and others of small 

 fragments of coal. The section presented a beautiful mi- 

 niature model of the stratification, fissures, slips, and faults 

 of a coal-field. These beds are covered by another of gra- 

 vel, which lies unconformable to them, and has evidently 

 been deposited immediately after, filling from above some 

 of the open fissures. It is impossible to account for these 

 appearances, without supposing that they are the effect of 

 a local upheaving. 



Although, however, the changes in level might in some 

 cases have been sudden and attended with earthquakes, it 

 is probable that in others they have been slow and gradual, 

 like those taking place in Sweden at the present day. In- 

 deed, with the exception of the absence of works of art, no- 

 thing can more perfectly agree with the appearances of the 

 ancient marine alluvial beds than Mr Lyell's description 

 of similar, but more recent, ones in Sweden. I have often 

 met with beds of shells embedded in marly clay, which had 

 received a violet colour from the decomposition of the com- 

 mon mussel (Mytilus edulis), exactly as described by him.* 



The question as to the identity of the flora and fauna of 

 the present period, with that of submergence, is an import- 

 ant one. It would perhaps be premature to say with cer- 

 tainty, whether they are identical or not. With regard to 

 the vegetation no observations which have yet been made 

 shew any difference between it and the existing race of 

 plants. But too little has been done in this department to 

 be of any value in settling the question. The same obser- 

 vation applies to the remains of birds and land animals ; or 

 to those of cetaceae, Crustacea, algae, zoophytes, and other 

 marine remains which have been found in these deposits. 



* Pbil. Trans. 1835, p. 1. 



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