KIPPLE MARKS.^ 



By Ch. Epry. 



[With 10 plates.] 



Among the multitudinous impressions which the ebbing tide leaves 

 on the sands as it recedes the most curious are certainly those parallel 

 lines of ridges, of varying size or regularity, covering at times im- 

 mense areas of the beach. They are known in French as Paumelles, 

 which has no significance, and in English as ripple marks, which 

 name has prevailed, perhaps because it is foreign, or perhaps because 

 it is more expressive (fig. 1).^ 



Ripple marks are everywhere so common that it is impossible to 

 walk on any beach for a few minutes without encountering them and 

 admiring them, as they always present a very beautiful appearance, 

 especially when seen in large masses in the sunlight, although one 

 may suffer from them, perhaps, if one is barefooted, as they make 

 walking very difficult. However, although they are universally 

 known, no one seems until now to have definitely ascertained their 

 cause. 



Some regard these undulations as due to the waves alone; others 

 consider that they are caused by the wind, by the transference of 

 the surface vibrations to the bottom, when these have only a little 

 depth of water to traverse in order to reach the latter. Learned 

 theories have also been formulated to explain them, none of which 

 give entire satisfaction. 



The question still remained, therefore, " What causes the formation 

 of these ripple marks ? " Wishing to answer it, I have taken the 

 opportunity, during a number of years, to observe attentively these 

 undulations wherever my tastes and fancy have taken me; that is 

 to say, from one end of our coast to the other, and the cause of the 

 phenomenon appears to me to-day so easy of comprehension that 

 I find it difficult to explain to myself wh}^ an agreement regarding 

 it was not reached long since. It is the very definite conclusion at 



1 Translated by permission from the Annales de I'lnstitut Oceanograpbiique (Pondation 

 Albert l'^'" Prince de Monaco). Paris, vol. 4, pt. 3, 1912. 

 - The tigures are shown on plates 1 to 10. 



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