LOCATION FELTA                   CA

Established Series
Rev. SBJ/TDC/GMK/ET
10/2025

FELTA SERIES

The Felta series consists of very deep, well drained soils formed in mixed volcanic alluvium and basic metamorphic rocks. Felta soils are on dissected terraces of the Coast Range of Northern California. Slopes range from 5 to 75 percent. The mean annual precipitation is about 30 inches (760 mm) and the mean annual air temperature is about 59 degrees F (15 degrees C).

TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, thermic Pachic Argixerolls

TYPICAL PEDON: Felta very gravelly loam - rangeland at an elevation of 244 m (805 feet). (Colors are for dry soil unless otherwise noted.)

A1--0 to 5 inches (0 to 13 cm); grayish brown (10YR 5/2) very gravelly heavy loam, very dark brown (10YR 2/2) moist; moderate very fine subangular blocky structure; slightly hard, friable, slightly sticky, slightly plastic; many very fine roots; many very fine and fine interstitial, and common fine tubular pores; slightly acid (pH 6.5); clear wavy boundary. (4 to 19 inches (10 to 48 cm) thick)

Bt1--5 to 14 inches (13 to 36 cm); grayish brown (10YR 5/2) very gravelly clay loam, very dark grayish brown (10YR 3/2) moist; moderate medium subangular blocky structure; slightly hard, friable, slightly sticky, slightly plastic; very fine and fine grass and tree roots; many fine interstitial pores; many thin clay films in pores; 80 to 90 percent cobblestones and gravel; slightly acid (pH 6.3); clear wavy boundary. (6 to 12 inches (15 to 30 cm) thick)

Bt2--14 to 24 inches (36 to 61 cm); grayish brown (10YR 5/2) very gravelly heavy clay loam, very dark grayish brown (10YR 3/2) moist; moderate medium subangular blocky structure; slightly hard, friable, sticky, slightly plastic; common medium and many very fine and fine roots; many very fine and fine interstitial and common fine tubular pores; many thin clay films in pores and as bridges; 50 to 70 percent gravel; slightly acid (pH 6.3); abrupt irregular boundary (6 to 14 inches (15 to 36 cm) thick)

C--24 to 60 inches (61 to 152 cm); grayish brown (10YR 5/2) and brown (10YR 5/3) very gravelly sandy clay loam, dark yellowish brown (10YR 4/4) moist; massive; hard, firm, slightly sticky, slighty plastic; few fine and medium roots; few fine tubular and common medium interstitial pores; many moderately thick clay films in pores and as bridges; about 80 to 85 percent mixed gravel of volcanic basic and rhyolitic rocks; strongly acid (pH 5.5)

TYPE LOCATION: Sonoma County, California one mile east of the junction of Chalk Hill Road and Pleasant Avenue; in the SE1/4 of the NW1/4 sec. 16, T.8N., R.8W.

RANGE IN CHARACTERISTICS: The mean annual soil temperature is about 59 to 65 degrees F (15 to 18 degrees C) and the soil temperature usually is not below 47degrees F (8 degrees C) at any time. The soil between depths of 8 to 20 inches (20 to 50 cm) is usually dry from June 15 until October 15 and is moist in some or all parts the rest of the year. Rock fragments of rounded pebbles and cobbles make up about 50 to 90 percent of the volume of the soil.

Typically, Felta soils have grayish brown, slightly acid, very gravelly heavy loam A horizons and grayish brown, slightly acid, very gravelly clay loam Bt horizons underlain by gravelly old alluvium at a depth of about 24 inches.

The A horizon is grayish brown or brown in 10YR or 7.5YR hue and has value of 5 dry, 2 or 3 moist and chroma is 2 or 3 both dry and moist. It is loam or heavy loam, and has moderate or weak subangular blocky structure. This horizon is neutral or slightly acid.

The Bt horizon has colors similar to the A horizon. It has weak or moderate subangular blocky structure. This horizon is slightly hard or hard and is slightly acid or moderately acid. The C horizon is pale brown to light brownish gray in 10YR hue and has value of 5 or 6 and chroma of 2 or 3. It is moderately acid or strongly acid.

COMPETING SERIES: These are the Lospinos series. Lospinos soils formed in shale and have a paralithic contact between 20 and 40 inches (50 and 100 cm).
Similar soils include the Botella, Elkhorn, Lockwood, and McCoy series. All these soils have less than 35 percent rock fragments.

GEOGRAPHIC SETTING: Felta soils are on dissected terraces at elevations of 100 to 2,000 feet (30 to 605 m). Slopes are 5 to 75 percent. The soils formed in mixed gravelly alluvium from mixed igneous rocks. The climate is subhumid mesothermal with hot dry summers and cool moist winters. Mean annual precipitation is 25 to 40 inches (635 to 1015 mm). Average January temperature is 47 degrees F (8 degrees C); average July temperature is 67 degrees F (19 degrees C); mean annual air temperature is 59 to 62 degrees F (15 to 17 degrees C). The freeze-free season is 220 to 280 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Boomer, Forward, Guenoc, Hambright, Kidd, and Laniger soils. Boomer soils have ochric epipedons, have less than 75 percent base saturation and have less than 35 percent coarse fragments. Forward soils have ochric epipedons and have medial control sections. Guenoc soils have ochric epipedons and have fine kaolinitic control sections with hue of 2.5YR or redder. Hambright and Kidd soils have a lithic contact at depths of less than 20 inches. Laniger soils have ochric epipedons and have medial control sections.

DRAINAGE AND PERMEABILITY: Well-drained; medium to rapid runoff; moderate permeability.

USE AND VEGETATION: The soils are used for grazing. Native vegetation is white oak, manzanita, annual grasses and shrubs. Some areas have a few black oak trees.

DISTRIBUTION AND EXTENT: Sonoma and Napa Counties, California, MLRA 15. The soils are moderately extensive.

SOIL SURVEY REGIONAL OFFICE (SSRO) RESPONSIBLE: Davis, California

SERIES ESTABLISHED: Napa County, California, 1974

REMARKS: The activity class was added to the classification in February of 2003. Competing series were not checked at that time. - ET
09/2025--Competing series checked and updated. -JBB

OSED scanned by SSQA. Last revised by state on 10/74

ADDITIONAL DATA:
Felta series description from the Soil Survey of Sonoma County California manuscript, 1972.

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National Cooperative Soil Survey
U.S.A.