Hunt — On the Action of Waves on Sea-beaches, 8fe. 285 



It may be olbserved, that the strength of the tidal currents at 

 Portland can throw no light on the exceptional height of the Chesil 

 Bank above the ordinary spring-tide level, however much the tidal 

 currents, owing to the peculiar conformation of the coast, may 

 augment the height of such ordinary level. 



The question of the motion of shingle and other objects along 

 the sea-bottom at a distance from the shore presents as great 

 difficulties to the student as its motion on and along sea-beaches, 

 owing to authorities being at so great variance both as to the 

 amount and cause of such motion. On the one hand, we have Mr. 

 J. M. Eendell expressing his opinion that shingle can scarcely be 

 moved by the heaviest waves at greater depths than three fathoms, 

 and on the other, Mr. J.T. Harrison speaking of " stones detached 

 from the rocks " being " carried along the coast in deep water, 

 knocked about here and there, and having their edges rubbed off in 

 all directions " (P. 38). We find Mr. F. Wynne going still further, 

 and maintaining that " the occurrence of any sort of rock as a 

 pebble " on the Chesil Beach proves " the existence of a more or 

 less exposed reef of that rock between the commencement of the 

 shallow water of the Channel and this beach " ; and further, that 

 " if syenite was found, then syenite existed in the bed of the Chan- 

 nel, perhaps as far as the entrance of the Bay of Biscay " (P. 47). 

 Between these two extremes all shades of opinion are held as to 

 the power of waves, tides, and currents to propel shingle along the 

 Channel floor. 



With respect to the existence of motion at considerable depths, 

 the facts recorded by Messrs. Douglass, Stevenson, and Winder 

 seem conclusive :—e.g. the lobster-pots filled with sand and shingle 

 during heavy swells in thirty-fathom water: the coarse sand 

 thrown on to the lantern-gallery of the Bishop Lighthouse (P. 46) : 

 the relation of the depth of water in which mud is found to be 

 deposited to the size of the waves that affect the locality {Steven- 

 sou on Barbours, 2nd ed., p. 21) : the passage of a piece of iron 

 plant round Dover breakwater in ten fathoms, whose track was 

 traced by Mr. Winder, when himself on the sea-bottom. — (Kinahan 

 on Sea-beaches, Proc. Boy. Irish Acad., 1879, p. 203.) In addition 

 to these may be cited the jar nearly full of sand and gravel trawled 

 off the Start {Trans. Dev. Assoc, vol. xii., p. 73, and Proc. Royal 

 Society, vol. xxxiv., p. 10.) ; and the soda-water bottle trawled 

 in about forty fathoms off the same headland, whose condition, as 



