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J. A. UDDEX 



momentary maximum, and falls again to zero. For particles of 

 different sizes, there must be different times of duration of speeds 

 attaining and exceeding the respective limits effective for their 

 transportation. This time, and hence the latitude of this effective 

 translator}- motion, will increase with the fineness of the stirred 

 sediment. With waves of one and the same size, and with the 



Fig. 5. — Ripple marks in Comanchean limestone in the bed of Bosque River, 

 about 6 miles north of Clifton, Texas. 



same depth of water, the width of ripple marks should be greater 

 in fine sediments than in coarse. The currents producing them 

 will carry fine elements farther than coarse. With waves of the 

 same size ripple-mark building in sand should then also take 

 place in somewhat more shallow water than ripple-mark building 

 in silt. 



Some ripple marks must be produced by a wavelike or rhythmic 

 motion which results from a reaction by the transported material 

 on translator}- bottom currents in water and in the air. No surface 



