168 Geological Society: — 



sequence of a tidal wave bringing high water, the tidal conditions 

 of the Irish Sea would be very different from what they are de- 

 scribed to be. 



He did not find any evidence of a plane of denudation on any 

 sea-coast, but, on the contrary, deep gorges and curved surfaces, 

 depth varying with width, &c. 



The nearest approach to a plane surface was in the estuan 7, of the 

 La Plata ; but that flatness appeared more the consequence of depo- 

 sition than denudation. 



The great cuts or indentations out of coast lines where rivers 

 discharge into the ocean, when compared with the absence of 

 indentations in areas where there are no great rivers, but where 

 the rocks are equally hard, showed that such denudation de- 

 pended upon the alternate and opposite action of rivers and the tide. 

 He referred to the removal of the bar of the Danube, and to the 

 groat laws which regulate the flow of water, which he illustrated by 

 diagrams. 



Hydraulics and meteorology must be studied in connexion with 

 the lines of denudation and deposition ; and however difficult and 

 inconvenient these subjects might be, no results would be reliable 

 unless all the physical circumstances were taken into account. 



January 5, 1876. — John Evans, Esq., P.R.S., President, 

 in the Chair. 



The following communications were read : — 



1. " Historical and personal Evidences of Subsidence beneath the 

 Sea, mainly if not entirely in the fourteenth and fifteenth cen- 

 turies, of several tracts of Land which formerly constituted parts of 

 the Isle of Jersey." By R. A. Peacock, Esq., C.E., F.G.S. 



In this paper the author brings forward a great number of details, 

 derived in part from personal observations and in part from ancient 

 documents, to prove that a considerable submergence of land has 

 taken place round the island of Jersey within comparatively recent 

 times. He referred principally to the existence of a submerged 

 forest in the Bay of St. Ouen, evidenced by the existence of stumps 

 of trees in the sea-bottom there, and by the traditional fact that up 

 to quite a late period fees were paid for privileges connected with 

 the forest of St. Ouen, although the forest itself had long previously 

 disappeared beneath the sea. Prom the evidence it would appear 

 that the submergence took place at the end of the fourteenth or the 

 beginning of the fifteenth century. The author also noticed the 

 occurrence of peat and submarine trees in the little bay of Greve de 

 Lecq on the north side of Jersey, and especially referred to the 

 evidence afforded by the Ecrehous rocks and Haitre Isle, there 

 having been in the latter a priory or chapel, supported by rents 

 derived from the parish of Ecrehous, which is now represented only 

 by a small islet, with the ruins of an ecclesiastical building upon it, 

 and a range of rocks protruding but little above the sea. 



