Tides in the Mediterranean and Adjacent Seas 317 



of the transverse oscillations may reach 0-5 cm, but generally they are smaller. 

 Longitudinal and transverse oscillations produce corresponding amphidromies 

 contra solem. Comparing with the observations, we can conclude that the 

 diurnal tides must be generated directly in the Baltic; the semi-diurnal tides, 

 on the contrary, should be considered as the superposition of the directly 

 generated and co-oscillating tides, the latter predominating by far. For the 

 tides of the Finnish and Bothnian bay, see Lisitzin (1943, 1944). 



3. The Tides of the English Channel and the South-western North Sea 



These two regions represent interconnecting channels between two tide- 

 carrying oceans; the boundaries in the west are a line from Isle d'Ouessant to 

 the Scilly Islands; in the east, a line connecting the Wash (south of Grimsby) 

 to the Island of Ameland off the Dutch coast. Hence, this includes the entire 

 English Channel and the Hoofden and connects the Atlantic Ocean with the 

 North Sea. 



Ranges and establishments for a great number of coastal localities are 

 given in Table 44. In the English Channel the establishment increases on 

 both the French and English coast from 4-5 h at the opening in the Atlantic 

 Ocean to 1 1 h in the Strait of Dover. However, the co-tidal lines do not 

 advance uniformly over the entire Channel. In the western part there are 

 rather great distances between the individual co-tidal lines, whereas they are 

 crowded in the narrow section of the Channel at the Cotentin Peninsula. 

 East of this region there are only very small differences in establishments 

 over a large area. This distribution of the co-tidal lines has no correlation 

 with the existing water depths. The ranges of the tides at the French coast 

 are considerably larger than at the English coast, which can be attributed 

 to the rotation of the earth (see p. 206). Disregarding the enormous range 

 at the inner end of the gulf of St. Malo (which are of a different origin) the 

 range decreases on both coasts until Cape De la Hague and St. Albans Head, 

 where the co-tidal lines are crowded as mentioned before. Then it increases 

 to a maximum off the Strait of Dover, where at spring tide, Hastings has 

 a range of 7-3 m, Treport in the south a range of 9-3 m. The minimum range 

 and the crowding of the co-tidal lines in the central narrow section of the 

 Channel would indicate the presence of a pseudo-nodal line of a standing 

 wave, especially since the difference in establishment between the western part 

 and the Strait of Dover is about 6 h. The distribution of the establishment 

 and of the range in the area east of the Strait of Dover (Hoofden) points 

 to a well-developed amphidromy contra solem, which was already assumed 

 by Harris (1904). 



The extraordinarily high tides occurring in the Gulf of St. Malo are due to the effect of reso- 

 nance between co-oscillating water-masses of the Bay of Normandy and the tide in the Channel. 

 This was proven by a simple computation of the co-oscillating tides of this bay, which gives an 

 increase in the range from about 5-8 m at the channel islands to about 12 m inside the Gulf. 



