196 FRANCIS RAMALEY 



as the last representative in many a moribund vegetation-capped 

 mound. Franseria and tansy also are not easily killed by the 

 blowing away of the sand from the substratum. If, however, 

 the sand is blown away very rapidly no vegetation can survive. 

 Here the ground will be strewn with a miscellaneous collection 

 of roots and branches of willows, lupines and other shrubby 

 plants. 



Distributed throughout the dune area there are many small 

 mounds 2 to 4 meters high capped with willow. These have 





Fig. 3. Young sand verbena (Abronia) just getting a foothold. 



been formed by a blowing away of the sand from all around 

 them. When such action is not too rapid the willows may grow 

 down the sides of the mound and thus persist for a long time. 

 Infilling may now occur and the former mound be partly cov- 

 ered. Often for a time a considerable moat-like depression will 

 encircle the mound only to be eventually filled up. 



The plants that best survive slow burial are the sand verbena, 

 Franseria, wild cucumber and willow. If infilling is very rapid 

 all vegetation is destroyed. 



