Driest during May and June. Typic aridic soil moisture regime. Surface layer averages 5 to 65 percent gravel. Brittle and firm or very firm when moist. Typically breaks down after prolonged soaking and shaking in water.
Roots can enter the matrix when moist but is root restrictive when dry.
Thought to be Pleistocene age sediments that were naturally compacted by a combination of paleo lake water loading and impregnation by calcium carbonate and low levels of silica. Driver soils are dry in all parts of the soil moisture control section from April to January. Palos Verdes soils are on relict fan terraces. Slopes range from 2 to 15 percent. They formed in fan alluvium from granite, gneiss, schist, rhyolite, latite and volcanic ash.