61 
Museum Bulletin No. 25. 
Plate III. 
A. Brook with rippled surface flowing over sand plain, showing appearance 
of the surface when ripple-mark is being formed on sand under 
shallow stream. (Page 12.) 
B. View on Grass river, New York, showing ripple-mark on left side and 
small terraces in middle of picture, left by falling stream. Photo 
by Orra P. Phelps. (Page 18.) 
