380 



Tides in the Mediterranean and Adjacent Seas 



According to coastal observations, we have in the Channel between the 

 Atlantic Ocean and the North Sea a tide wave with two pseudo-nodal lines, 

 one north of the Cotentin Peninsula and one in the Hoofden. The rotation 

 of the earth causes the tidal range to be greater on the French coast and to 

 transform the nodal line in the Hoofden into an amphidromy. 



The tidal currents in the English Channel have been described extensively 

 by Stok, 1905; Dalhuisen, 1907 and in a publication by the Deutsche 

 Seewarte (1905). Borgen (1898) has discussed these currents. The lines of 

 convergence and divergence which shift during a tidal period are especially 

 well suited to characterize the current. Borgen distinguishes three boundary 

 lines: the "Atlantic", which is west of the Greenwich meridian, the "Channel 

 line" east thereof and south of 52t° N. lat., and the "North Sea line" which 



Table 45. Position of lines of convergence and divergence 

 in the English Channel 



Time 



Lines of convergence and divergence 



Con. | 

 Div. I 



Atlantic 



Con. | 

 Div. J 



Channel 



Con. \ 

 Div. I 



North Sea 



1 h after 



5 h before 



2 h after 



4h before 



3 h after 



3 h before ) 

 4h after 



2h before J 

 5 h after 



1 h before ) 



Low water 



High water 



High water 



at 



Dover 



High water 



at 



Dover 



High water 



at 



Dover 



High water 



at 



Dover 



High water 



at 



Dover 



} at Dover 



Lands End 



to 

 Isle of Bas 



Falmouth, Plymouth 



Entrance to 

 Bay of Normandy 



Start Point 



to 



Casquets 



Lyme Regis 

 to 

 Cap de la Hague 



Large area with no 



currents south of 



Isle of Wight 



Hastings, Eastbourne 



to 



Fecamp, Dieppe 



Hastings 



to 



Treport, Cayeux 



Ryebay 



to 



Estuary of Somme 



Dungeness 



to 

 Authie Bay 



Margate 



to 



Gravelines 



Thames Estuary 



to 



Ostende 



Hoek van Holland 

 Ijmuiden toward 



NNW. 



Ijmuiden, Helder and 



Cromer, Washbucht 



to NNE. 



Washbucht to NE. 

 and Terschelling 



to WNW. 



Outside eastern 

 outlet 



belongs already more to the system of the North Sea currents. Table 45 

 gives information concerning the position of these boundaries for all tidal 

 hours. One can see how each of them apparently travels from west to east 

 through the entire channel. The "Atlantic" and the "North Sea" boundaries 



