Windblown dust and sand The mapped distribution of windblown dust and sand from two aerial photographs taken 36 years apart shows many differences. We can see these environmental changes as broader distributions of wind-deposited sand, mostly east and northeast of the Main Post. It was probably caused by increased vehicular traffic and loss of vegetation, which made more land vulnerable to wind erosion. In fact, the west desert is bounded by two of the biggest and most dangerous faults in the U.S., the San Andreas and Garlock faults.
Faults are solid lines where well known, dashed where less certain, and dotted where covered.
Faults on this map tend long mountains and ridges. A plot of faults on a shaded relief map shows this relationship. Where possible, excavations and natural stream cuts were used to determine the youngest surficial deposits broken by fault movement, and the oldest deposits unbroken. These two ages bracket the age of the last fault rupture. Ages of deposits, however, are only broadly known through correlation with dated deposits elsewhere in the desert.