THE SEVERN TUNNEL SECTION. 85 



growth would raise it sornowhat higher still. . . . After 

 a long pause, during which the lower pc.at, with its associ- 

 ated remains of forests, was formed, subsidence set in again, 

 and the lower blue cl.ay gradually accumulated over the 

 layer of vegetable matter. Another interval of rest suc- 

 ceeded, during which a new alluvial surface rose above the 

 tide, and the npper bed of peat was produced; again the 

 movement of depression was renewed, and apparently not 

 uniformly, since the lower part of the upper clay contain.s 

 scattered fragments of plants whicli were probiibly dei'ivcd 

 from some exposed portion of tlie peat, which the waves 

 ploughed to pieces and distributed far and wide. . . . 

 Finally, the upper part of the blue clay was deposited, and 

 this is more arenaceous than the lower part of the same 

 deposit, because the continued depression had brought the 

 sea nearer the area of deposition." (Q. J. 0. 8. XXXIX. 



cm-4,.) 



Of the blue clay of the Severn alluvium. Professor Sollas 

 says : " The blue silt of the Severn alluvium is strikingly 

 similar in all its characters to the modern ooze ; it consists of 

 a similar admixture of mud and angular silioious fragments, 

 while marine Sponge-spicules, Koraminifera, CoccoHths, 

 and other mai-ino remains similar to tliose of the modem 

 silt, are universa,lly disseminated tlironghont its mass." 

 (Loc. cit. 615.) 



The peat in the tunnel section, as at Porlock and clse- 

 whei-c, contains abundant remains of yellow iris flags. Tree 

 trunks (oak) wore found, but I am not aware of any dis- 

 covery of mammalian remains. 



In this connection a quotation from Mi'. Lucy's paper, 

 in the Prnc. of the Gottcftniold Oluh, on " The Submerged 

 Forest, Holly ]Ia,/,lo, Sharpness," may be of interest: — - 



" The Peat Bed, near Sharpness, lies in a hollow, very 



