The dominant rocks are composed of six medium-textured soils of the Laughlin, Josephine, Sutherlin, Maymen, Los Gatos , and Hugo series. The Yorkville soils are a heavy clay characterized by landslips and seep areas. The moderately shallow soils of the Laughlin series are slightly acidic with depths ranging from 1 ft to 3 ft. Distributed throughout the lower elevations of HREC, these soils are on nonsteep to steep, partly rounded slopes. The Josephine soils are distributed throughout the station and occur on nonsteep to steep slopes, most of which face toward the north or east.
Surface soils are slightly acidic, subsurface soils are moderately acidic.
Soil depths range from less than 36 inches to more than 60 inches. Typical vegetation of this soil is moderate to dense hardwoods with some shrubs and conifers. Sutherlin soils, widely distributed on HREC, have developed from hard sandstone and shale and are typically grass-covered with scattered blue oaks and interior live oaks. Soil depth is usually less than 3 ft and surface soils are slightly acid. These soils are on nonsteep to steep rounded slopes.