A COMPARISON OF THE CAMBRIAN AND ORDOVICIAN 

 RIPPLE-MARKS FOUND AT OTTAWA, CANADA^ 



E. M. KINDLE 



Geological Survej^ of Canada, Ottawa 



Introduction. — We are told by an eminent geographer that ''the 

 most important part of the geological labors of the ocean is hidden 

 from our eyes."^ The evident truth of this observation affords a 

 sufhcient reason for making a careful record of every fact which 

 may help to throw light on the processes of sedimentation. Ripple- 

 marks on sandstones and sandy shales are among the most familiar 

 of the characters with which marine sediments have been impressed, 

 but we have yet much to learn concerning them. These features 

 when fully understood will tell us much more of the local physical 

 conditions under which they were formed than we are at present 

 able to infer from them. It still remains for future research to 

 determine whether a law can be deduced which will connect the 

 length and height of waves with the width of the ripple-marks result- 

 ing from the simultaneous water oscillation. Among the present 

 needs in connection with the effort to acquire a more fundamental 

 knowledge of ripple-mark phenomena appear to be recorded data 

 on (i) the different types of ripple-marks to be met with in a given 

 set of beds where the factors of depth and texture of sediment are 

 uniform, (2) characteristics which distinguish ripple-marks asso- 

 ciated with particular kinds of sediment from those found in other 

 sediments. 



The observations in this paper are recorded with this twofold 

 object in mind. The Cambrian and Ordovician sediments both 

 show well-developed ripple-marks in horizons which are exposed in 

 the Ottawa district. The Cambrian ripple-marks which will be 

 described occur in sandstone, while those in the Ordovician are 

 impressed upon limestone. 



^ Published with the permission of the Director of the Geological Survey of 

 Canada. 



^ Elisee Reclus, A New Physical Geography, Vol. II (1890), "The Ocean," p. 103. 



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