CLEMENTS 



PLATE 10 



A. Gravel ridges produced by a gold dredge, Chico, California. 



B. Pond formed by a beaver-dam, Superior National Forest, Minnesota. 



C. Bare areas in Franseria-Abronia associes due to the destruction of the dominants 

 by Cmcuta salina, Medanos Spit, San Diego, California. 



