38 



G. H. KINAHAN ON THE CHESIL BEACH, DORSETSHIRE, 



till it reaches the nodal line 

 off Swanage, a distance of 150 

 miles. 



13. The current in the Chan- 

 nel between Portland Bill and 

 Cape la Hogue is about 3*5 knots 

 an hour*. 



14. In Lyme Bay there is a 

 small bank (Skerries bank) at 

 the S.E. of Start Bay. 



15. As there are no off-shore 

 banks across the mouth of Lyme 

 Bay, also as the narrow between 

 Portland Bill and Cape la Hogue 

 tends to augment the force of the 

 current, already progressively in- 

 creasing, after it has passed Start 

 Point and is approaching the 

 Swanage nodal line, the land- 

 ward movement of the water 

 into Lyme Bay from the main 

 up -channel current ought to in- 

 crease progressively in power 

 from Start Point to Portland 

 Bill. 



16. As the tidal wave going 

 eastward up the English Channel 

 proceeds much faster at the centre 

 than on its margins (see any co- 

 tidal map), there is necessarily 

 an " offing tide " setting into the 

 different bays. This ought to 

 tend to generate " on-shore" or 

 " countertides " at the eastern 

 sides of the different bays. If 

 such a countertide existed to the 

 east of Lyme Bay, it would cause 

 a driftage northward from the 

 Bill of Portland toward Chesil- 

 ton. It would also account for 

 the Chesil beach ending at Che- 

 silton. 



17. The fifteen-, twenty-, and 

 twenty-five-fathom lines on the 



reaches the nodal line off Cour- 

 town, a distance of 150 miles. 



13. The current in the Chan- 

 nel between Cahore Point and 

 Braichypwll is 2*5 knots an hour. 



14. In Wexford Bay there are 

 many off-shore banks, principally 

 in a line between Greenore and 

 Cahore Points. 



15. On account of the off- 

 shore banks in Wexford Bay the 

 landward movement from the 

 main up-channel current can- 

 not increase progressively in 

 strength. There are also "cross 

 tides" generated by the efflux 

 from the Wexford-Harbour la- 

 goon that modify considerably 

 the effects of the landward move- 

 ment from the main current. 



16. At Cahore Point there is a 

 " countertide " running on shore 

 towards the S.S.W. for the last 

 three hours of the " flow." This 

 tide is due to the on-shore set 

 of the " offing tide" generated 

 by the tidal wave running much 

 quicker up the centre of the Irish 

 Sea than at its margins. This 

 countertide has stopped the 

 shingle beach from extending on- 

 to Cahore Point. 



17. The soundings on the 

 Admiralty Charts would suggest 



* Between the line joining Start Point and the Casquets (islands a little west 

 of Cape la Hogue) and the line joining Beachy Head and Cape Ailly (near 

 Dieppe) the flow of spring tides is as follows : — west part 23 knots, central 

 part 36 knots, east part 3 knots, off Cape Barfleur 5*4 knots, and over Hurd's 

 Deep 2*16 knots per hour. 



