They formed in aerially deposited volcanic ash and lahar of sand, gravel, and volcanic ash overlying weakly cemented very gravelly lahar. Slopes are 0 to 60 percent. The climate is marine and is characterized by warm, dry summers and cool, moist winters. The average annual precipitation is 55 to 70 inches, which falls mostly as rainfall during the winter. These are the Greenwater , Natal , Sara , Seaquest , and Solo series.
Natal soils are fine and poorly drained.
Sara, Seaquest, and Viola have an argillic horizon. In addition, Sara and Seaquest soils are fine. Solo soils are more than 20 inches deep to cemented lahar. Greenwater soils are deep sand. Moderately well drained.