Studies for Students 



CONTRIBUTIONS TO THE STUDY OF RIPPLE MARKS 



DOUGLAS W. JOHNSON 

 Columbia University 



The two interesting papers on ripple marks by E. M. Kindle 

 and J. A. Udden, published in the Journal of Geology for October- 

 November, 1914, and February-March, 1916, respectively, suggest 

 that readers of the Journal might be interested in a brief review 

 of certain previous contributions to the subject, particularly since 

 most of the questions raised by these two writers have occupied 

 the attention of earlier investigators. In connection with a study 

 of wave action, I have recently had occasion to consult a number 

 of reports on ripple marks, and offer in the following para- 

 graphs a synopsis of some essays not mentioned by Kindle 

 or Udden. No attempt has been made to compile a complete 

 bibliography of the subject, but reference is made to most of 

 the more important papers which have come to the writer's 

 attention. 



The accumulation of sand and finer debris in parallel ridges and 

 troughs somewhat resembling water waves in form, though not 

 at all in origin or in method of formation, was long ago recognized 

 as a normal product of wave and current action. Under various 

 names, such as " current mark," "wave mark," "ripple drift," 

 "current drift," and "friction markings," the phenomenon now 

 generally known as ripple mark has repeatedly been described. 

 Although not infrequently found on sandy beaches, ripple marks 

 are perhaps better developed on tidal flats and over the broad 

 bottoms of shallow estuaries, lakes, and ponds. They are not 

 unknown on the deeper sea floor of the off-shore zone, where their 

 occurrence to a depth of over 600 feet has been demonstrated. 

 Ripple marks which are exposed by the falling tide may be 



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