10 THE LAW OF DEPOSIT VI. 



it takes a new form. The water inside of the breaker presents the appearance of a 

 plane, more or less inchned, the surface of which is broken by small raised waves, 

 without any companion hollows, that is, waves of the first order, which are every- 

 where breaking, and everyivhere, therefore, exerting the projectile force, by virtue 

 of which any matter held in suspension is thrown out and forward, while any sub- 

 stances upon which they impinge receive a shock that tends to force them still far- 

 ther up on the beach."^ 



There are two or three characteristic features of the searbeaches, which exem- 

 plify this action, and which fall under the most cursory observation. I referred to 

 them in the beginning. One is sear-weed, the others shingles, or stones and wrecks. 

 Every one must have noticed how the light sea-weed, which is easily moved, shows 

 by an exact and well-defined line the limit of height of the water at the preceding 

 flood tide. Indeed, there will be several such lines seen on most beaches where the 

 weed is abundant, each one corresponding to different heights, and these lines vary 

 from time to time. The heavier material, however, of the stones and wrecks, is 

 found farther up on the beach, and shows the extent to which the mechanical action 

 of the water has reached in great storms. They are only moved by the violent 

 impulses belonging to the action of waves generated by violent tempests. 



Such then I conceive to be the mode of mechanical action, by which the law of 

 deposit of the flood tide operates. The inward tendency of the wave action on the 

 shore, ejects, or repels, as it were, the matters brought under its influence, and the 

 transporting power of the flood current bears them from place to place, bringing 

 them finally under this influence. And further, as the mechanical force of the flood 

 current gives to the breaking wave an inclination in the direction of its course, 

 the projected particle will not strike the beach perpendicularly to its length, but 

 obhquely, so that it will advance, as it rises on the shore ; and ia this manner, also, 

 the combiaed action of the two forces leads to the accumulation of deposits in the 

 direction of the flood tide. 



Herein is contained an explanation of the connection between the manner in 

 which waves approach sear-beaches, and the local direction of the flood current; 

 which was recorded in the Memoir, p. 140. And lastly, the action of the great 

 oceanic tide wave, if, as was before observed, it approached a searcoast without 

 interruption, would be similar ; that being regarded by Mr. Kussell as a wave of the 

 first order. 



If this mode of deposit of the flood tide be regarded as a fundamental and per- 

 manent law, and it would seem to be so, then it becomes of interest to inquire into 

 its design, and into the results it has effected in the long lapse of time, the secula 

 seculm-um, during which our earth has been undergoing modification and transfor- 

 mation. And in order to do this briefly, I will select for an example a period in 



* This change from the sea wave, or wave of the second order, to the wave of the first order, in the 

 course of which the motion of oscillation of the water particle is transformed into a motion of translation, 

 may be compared to Mr. Russell's case of " Genesis by a column of fluid," acting, to use his language, as 

 a " mechanical prime mover," by means of which that wave is generated which exhibits throughout its 

 action, the " transmission of mechanical force." 



