428 CASTS OF MUD FURROWS, WAVE LINES, &C. 



sandy shores of our large lakes, when, towards evening, the wind 

 dying away, leaves long beaehes covered with these delicate 

 lineations. It often happens, that during this process several suc- 

 cessive lines are left, and then a wave larger than the rest advan- 

 ces and sweeps aw^ay the whole, forming a line still higher up 

 the beach. But at the same time the wave may not reach as far 

 laterally, and then we have the appearance of a single line in the 

 centre, separating into several at the two extremities. This is 

 readily conceived, if the same fact has not been observed, and it 

 is illustrated in the wood cut. 



The process by which the ridge or line is formed, seems to be 

 this. The advancing wave, by its momentum, carries forward a 

 small quantity of sand upon its crest ; when the w^ave reaches 

 its limit, the momentum being lost, and the sand being in ad- 

 vance, there is no force to carry it back w^ith the retiring water, 

 and it is thus left upon the beach marking the extreme verge of 

 the wave. This seems to be the simple and rational explanation, 

 where the wave is advancing directly upon the shore. When the 

 direction of the wdnd is oblique to that of the shore, the wave 

 sweeps onward, advancing upon and receding gi-adually from the 

 shore ; in such cases the deposition seems to take place from the 

 centrifugal action of the wave throwing the sand beyond the 

 limit of its powder. 



If from the sandy beaches of our lakes and from the sea-shore 

 we go to the sandstone quarries, the analogy of these lines is too 

 close to be mistaken. It leaves no doubt as to the cause. It 

 seems as if the lake or sea beach had been converted into solid 

 stone while yet washed by the waves, and w'e can almost fancy 

 that the returning tide will obliterate them all. It is, indeed, re- 

 markable, that these faint traces of waves should be preserved 

 through successive layers, for many feet in thickness. How^ could 

 these faint lines in the loose sand of a sea-beach have been pre- 

 served while other depositions were being made upon them? 

 And how could the sea have retired, and again have covered the 

 surface, leaving as it went these lines, and returning, apparently 

 with a fresh deposit, which, on retiring again, was left marked by 

 its retreating lines ? It may not, indeed, be easy to answer sat- 

 isfactorily in what manner this was done, but it seems very ration- 



