794 



TEXTBOOK OF BOTANY 



Fig. 423. Picture taken during a sand storm in Dallas County, Texas. The farm has 

 been ruined by wind erosion of soil. Photo by U. S. Soil Conservation Service. 



Fig. 424. Dust storm in Prowers County, Colorado; wind velocity, 30 miles per 

 hour; duration of storm, about 3 hours. Photo by U. S. Soil Conservation Service. 



