LOCATION AHWAHNEE           CA
Established Series
Rev. GLH/RCH/LCL/DJE
11/98

AHWAHNEE SERIES


The Ahwahnee series consists of moderately deep, well drained soils formed in material weathered from granitic rocks. These soils are footslopes and mountains. Slope is 2 to 75 percent. The mean annual precipitation is about 30 inches and the mean annual temperature is about, 60 degrees F.

TAXONOMIC CLASS: Coarse-loamy, mixed, active, thermic Mollic Haploxeralfs

TYPICAL PEDON: The representative profile for this soil is on a slope of 12 percent under annual grasses and occasional blue oak, at an elevation of 1,260 feet. (Colors are for dry soil unless otherwise stated. When described on July 16, 1978 the soil was dry to 17 inches and moist below.)

0i--1/4 inch to 0; scattered litter from annual grass and forbs.

Al--0 to 1 inches; grayish brown (10YR 5/2) coarse sandy loam, very dark grayish brown (10YR 3/2) moist; moderate fine granular structure; soft, friable, slightly sticky and nonplastic; common very fine roots; many very fine and fine interstitial pores; medium acid (pH 5.8); abrupt wavy boundary. (1 to 2 inches thick)

A2--1 to 8 inches; grayish brown (10YR 5/2) coarse sandy loam, very dark grayish brown (10YR 3/2) moist; massive; slightly hard, friable, slightly sticky and nonplastic; few very fine and fine roots; common fine interstitial pores; medium acid (pH 5.8); clear smooth boundary. (3 to 7 inches thick)

BA--8 to 17 inches; brown (10YR 5/3) coarse sandy loam, dark brown (10YR 4/3) moist; massive; slightly hard, friable, slightly sticky and nonplastic; common fine interstitial and few fine tubular pores; few colloidal stains on mineral grains; medium acid (pH 6.0); gradual smooth boundary. (5 to 15 inches thick)

Bt--17 to 29 inches; yellowish brown (10YR 5/4) coarse sandy loam, dark brown (10YR 4/3) moist; massive; hard, friable, slightly sticky and nonplastic; few fine medium and coarse roots; common fine interstitial and few fine tubular pores; common colloidal stains on mineral grains, few bridges, and few thin clay films line pores; medium acid (pH 6.0); abrupt irregular boundary. (11 to 16 inches thick)

Cr--29 to 42 inches; granodiorite weathered to grus.

TYPE LOCATION: Fresno County, California; about 1 mile south of Kerckhoff Lake, about 30 feet north, 12 degrees west of live oak tree in pasture, in front of a residence; in the NW 1/4 of the NE 1/4 of section 19, T. 9 S., R. 23 E.; North Fork Quadrangle; Pineridge Ranger District.

RANGE IN CHARACTERISTICS: Depth to a paralithic contact of weathered granitic rock is 20 to 40 inches. The soil between depths of about 8 and 33 inches is usually moist but is dry in all parts from a h ut midDMay until late October. Mean annual soil temperature varies from about 63 to 68 degrees F. Base saturation by sum of cations averages between 50 to 75 percent throughout. The soil is medium acid or slightly acid throughout.

The A horizons have dry colors of 10YR 5/3, 3/3, 5/2, 4/2. Moist colors are 10YR 3/3 or 3/2. The surface 4 to 6 inches averages 1 to 3 percent organic matter and is less than 1 percent at 8 inches. It is sandy loam or coarse sandy loam. The lower boundary is clear or gradual or a transition horizon is present.

The Bt horizon has dry colors of 10YR 4/3, 4/4, 4/6, 5/3, 5/4, 5/6, 6/3, 6/4, 6/6 and 7.5YR 4/4, 4/6, 5/4, 5/6, 6/4 or 6/6. Moist colors are 1 or 2 units of value darker. It is sandy loam or coarse sandy loam with 14 to 18 percent total clay. Increase in clay content from the A to Bt horizon is 3 to 5 percent.absolute.

A C horizon may be present between the Bt and the paralithic contact. When present it is sandy loam.

COMPETING SERIES: There are no other soils in this family.

GEOGRAPHIC SETTING: Ahwahnee soils are on gently sloping footslopes to very steep mountains. Slope is 2 to 75 percent. These soils formed in material weathered from granitic rocks. Elevation is 200 to 2,800 feet. The climate is subhumid with hot dry summers and cool moist winters. Mean annual precipitation is 15 to 45 inches. Mean annual temperature is about 60 degrees F., average January temperature is about 43 degrees F. and average July temperature is about 79 degrees F. Frost-free season varies from about 175 to 260 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Auberry, Auburn, Coarsegold, Shenandoah, Sierra and Tollhouse series. Auberry, Coarsegold, Shanandoah, and Sierra soils all have argillic horizons with greater than 18 percent clay. Auburn soils lack an argillic horizon and are fine-loamy. In addition, Shenandoah soils have mottled Bt horizons. Tollhouse soils are less than 20 inches to bedrock and lack an argillic horizon.

DRAINAGE AND PERMEABILITY: Well drained; runoff is slow on the gentle slopes and very rapid on the very steep slopes; moderately rapid permeability.

USE AND VEGETATION: Used mainly as winter and spring range; some summer dry pasture. Small areas have been cleared and used for grain-hay production. Vegetation is open to semidense cover of woodland-grass and shrub species.

DISTRIBUTION AND EXTENT: The upper western foothills of the Sierra Nevada Mountains and southern Coast Range, California. The soils are extensive.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California

SERIES ESTABLISHED: Madera Area, California, 1959.

ADDITIONAL DATA:S78CA-019-001 (type location); NSSL pedons S55CA-079-001 and S61CA-017-006. Two pedons in Amador County that were correlated to Ahwahnee in the Amador published soil survey report but are Haploxerolls taxadjuncts. S59CA-005-017 and S59CA-005-018. These two pedons were sampled as San Andreas.

REMARKS: Ahwahnee soils were formerly classified as Mollic Haploxeralfs. Ahwahnee soils as mapped in east Fresno, Madera, ElDorado and Nevada counties, California would now be classified as Typic Haploxeralfs, Ultic Haploxeralfs and Mollic Haploxeralfs.

OSED scanned by SSQA. Last revised by state on 3/84.


National Cooperative Soil Survey
U.S.A.