Burton ; Lincolnshire Coast Boulders. 109 
its effect on the beach less mordant. In this case eee the 
whole of the energy of the wave is absorbed by the friction.’ 
‘On flat, sandy shores, the waves first break seaward of the 
low water line, a succession of smaller waves following up to 
the margin of the water. 
‘From the seaward side of the breaking point of the wave 
no material is carried shorewards on to the beach, the motion of 
the water continuing as an undulation.’ 
‘It is stated that stones lying on the sea-bed are moved and 
displaced during heavy gales by the waves to depths of six or 
seven fathoms and even more. So long as these waves remain 
undulations, the movement cannot extend beyond the orbit of 
wave formation, and there cannot, therefore, be any translation 
of the stones shorewards.’ 
‘In the formation of waves, besides the vertical movement 
of the particles of water which places the crest above the trough, 
there is an oscillating, horizontal movement, alternately towards 
and away from the shore. Any material susceptible of move- 
ment, lying on the bed of the sea, actuated by the waves, is 
moved alternately backwards and forwards, the mass of the sub- 
Stance and the distance over which it is moved depending on the 
height and on the length of the waves. As the places on which 
these waves act incline from the shore seaward, owing to the 
laws of gravity, the retrograde action of the wave must be most 
effective in the movement of material, and the tendency be rather 
to drag the material away from, than to push it towards the shore.’ 
‘Action of gravity. As already pointed out, the slope of 
a beach is seaward.’ 
‘By the law of gravitation, all material in movement has 
a natural tendency to work downwards unless prevented by 
Some stronger opposing cause. Breaking waves no doubt have 
Sufficient force, under certain conditions, to counteract this 
downward movement, but their general tendency is to aid the 
seaward movement by their undertow. 
‘It is due to the seaward action of the undertow of the waves 
that bays and indents along the coast are kept open and free 
from accumulation of deposit.” 
‘It is true that stones and other substances of considerable 
Size and weight, which have been buried in the sand for longer 
or shorter periods, are occasionally, in heavy gales causing high 
Waves, lifted up, carried forward, and left stranded on the 
beach. These, however, are only rare and isolated events which 
occur during very heavy gales.’ 
April: ‘1899. 
