626 ON THE ESTUAE1ES OF THE SEVERN AND ITS TEIBUTAEIES. 



■was formed of material deposited by the up-tide, so that the mate- 

 rials were derived from the Yorkshire coast. The sections of the 

 Severn alluvial flats corresponded with those of the Penland. He 

 thought it would be better to say that submerged forests occur at 

 the junction of a river with the sea, rather than on a low shelving 

 shore, as stated by Prof. Boyd Dawkins. " Submerged forests" and 

 " peat-beds" were substantially the same phenomenon. It was, 

 however, important to remember that the subsidence need only be 

 slight. He had lately heard some facts with reference to the action 

 of the tide in the Thames : — experiments had been made with 

 floats, and in some cases the floats were found after a fortnight or 

 more to have travelled up the stream ; others, however, had slowly 

 descended. It was therefore evident that much remained to be 

 learned about the tides. 



Prof. Sollas was glad to find that the results of his study of this 

 particular estuary were sufficiently in harmony with Prof. Dawkins's 

 generalizations. He differed, however, in two particulars : the first 

 was with reference to the deposits immediately beneath the peat, 

 which he regarded as not fluviatile, but tidal or marine ; and the 

 second as to the extent of the submergence which had taken place 

 subsequent to the formation of the peat ; he thought the land need 

 not have scood more than 20 feet higher than at present for the 

 growth of the first peat-bed, and 10 feet for the second. 



