LOCATION HETCHY                  CA

Established Series
SMM/CES/TKK/JW
08/2022

HETCHY SERIES

The Hetchy series consists of moderately deep, well drained soils formed in colluvium and residuum weathered from phyllite, schist, and other metasedimentary rocks. The Hetchy soils are on hills and ridges. Slopes range from 3 to 60 percent. The mean annual precipitation is about 860 mm and the mean annual air temperature is about 15 degrees C.

TAXONOMIC CLASS: Loamy-skeletal, mixed, active, thermic Ultic Haploxeralfs

TYPICAL PEDON: Hetchy very gravelly sandy loam on a west-facing, 15 percent, convex slope under blue oak and annual grasses at an elevation of 600 meters. (Colors are for dry soils unless otherwise noted. When described on June 11, 2008 the soil was dry throughout.)

A--0 to 4 cm; brown (10YR 4/3) very gravelly sandy loam, very dark brown (7.5YR 2.5/2) moist; weak fine granular structure; slightly hard, friable, slightly sticky, slightly plastic; many very fine roots throughout; few very fine irregular and tubular pores; 30 percent subangular strongly cemented phyllite gravel; slightly acid (pH 6.5); clear smooth boundary. (3 to 10 cm thick)

BA--4 to 20 cm; dark yellowish brown (10YR 4/4) gravelly sandy loam, dark brown (7.5YR 3/2) moist; strong medium subangular blocky structure; moderately hard, firm, slightly sticky, slightly plastic; many very fine and fine roots throughout; common very fine and fine irregular and tubular pores; 15 percent subangular strongly cemented phyllite gravel; slightly acid (pH 6.4); clear smooth boundary.

Bw--20 to 42 cm; dark yellowish brown (10YR 4/4) extremely cobbly sandy loam, dark brown (7.5YR 3/2) moist; strong coarse subangular blocky structure; moderately hard, firm, slightly sticky, slightly plastic; many very fine and fine, and few medium and coarse roots throughout; many very fine and medium tubular and many very fine, fine, and medium irregular pores; 10 percent subangular very strongly cemented phyllite gravel, 45 percent subangular very strongly cemented phyllite cobbles, 10 percent subangular indurated phyllite stones; slightly acid (pH 6.5); clear wavy boundary. (0 to 23 cm thick)

Bt1--42 to 56 cm; dark yellowish brown (10YR 4/4) very cobbly loam, dark brown (7.5YR 3/3) moist; strong coarse subangular blocky structure; moderately hard, firm, slightly sticky, slightly plastic; many very fine and fine, common medium, and few coarse roots throughout; common fine and medium tubular and common fine irregular pores; 10 percent faint clay films on all faces of peds; 15 percent subangular indurated phyllite gravel, 30 percent subangular indurated phyllite cobbles, 15 percent subangular moderately cemented phyllite paragravel, and 10 percent subangular moderately cemented phyllite paracobbles; slightly acid (pH 6.4); gradual wavy boundary.

Bt2--56 to 70 cm; strong brown (7.5YR 5/6) very cobbly loam, dark brown (7.5YR 3/4) moist; strong coarse angular blocky structure; very hard, very firm, moderately sticky, moderately plastic; common very fine roots throughout; common fine tubular and irregular pores; 35 percent distinct clay films on all faces of peds; 3 percent fine mica flakes; 25 percent subangular strongly cemented phyllite gravel, 25 percent subangular strongly cemented and indurated phyllite cobbles; slightly acid (pH 6.3); gradual wavy boundary.

Bt3--70 to 90 cm; strong brown (7.5YR 5/6) very gravelly loam, brown (7.5YR 4/4) moist; strong medium angular blocky structure; moderately hard, firm, moderately sticky, moderately plastic; common very fine roots throughout; few fine tubular and irregular pores; 20 percent distinct clay films on all faces of peds; 3 percent fine mica flakes; 45 percent subangular strongly cemented phyllite gravel, 15 percent subangular moderately cemented phyllite paragravel; slightly acid (pH 6.5); clear wavy boundary. (Combined thickness of Bt horizons is 20 to 70 cm)

Cr--90 to 102 cm; moderately cemented phyllite bedrock, fractured at intervals of 10 to 45 cm; abrupt irregular boundary. (13 to 25 cm thick)

R--102 to 127 cm; very strongly cemented phyllite bedrock, fractured at intervals of 10 to less than 45 cm.

TYPE LOCATION: Tuolumne County, California, about 11 km (6.8 miles) southeast of Sonora; USGS 7.5 minute topographic quadrangle: Standard, California; WGS84 37.887775 latitude and -120.319717 longitude; UTM Zone 10 735690 meters N 4196740 meters N NAD83.

RANGE IN CHARACTERISTICS:
Soil temperature: The mean annual soil temperature at 50 cm is 15 to 17 degrees C and the difference between mean summer and mean winter soil temperature is greater than 6 degrees C. The soils have a thermic temperature regime.

Soil moisture: The soil moisture control section is dry in all parts from about May to October. The soils have a xeric soil moisture regime.

Diagnostic Feature(s):
Ochric epipedon thickness: 5 to 25 cm
Argillic horizon thickness: 20 to 70 cm
Depth to paralithic contact: 50 to 100 cm
Depth to lithic contact: 60 to 110 cm

Reaction: strongly acid to slightly acid

Particle size control section weighted average:
Rock fragments: 35 to 60 percent
Clay content: averages 18 to 35 percent clay

Base saturation: less than or equal to 75 percent in one or more subhorizons of the argillic horizon (by sum of cations).

A horizon
Hue: 7.5YR, 10YR
Value: 4 or 5 dry, 2 to 4 moist
Chroma: 2 to 4, dry or moist
Texture: sandy loam, fine sandy loam, silt loam, loam
Clay content: 8 to 20 percent
Rock fragments: 0 to 40 percent
0 to 40 percent gravel
0 to 40 percent channers
0 to 15 percent cobbles

Bw horizon (when present)
Hue: 7.5YR, 10YR
Value: 4 or 5 dry, 4 moist
Chroma: 4 or 6, dry or moist
Texture: sandy loam, silt loam, loam
Clay content: 15 to 20 percent
Rock fragments: 20 to 60 percent
0 to 50 percent gravel
0 to 50 percent channers
0 to 15 percent cobbles
0 to 10 percent stones

Bt horizon(s), upper part
Hue: 5YR, 7.5YR, 10YR
Value: 4 to 6 dry, 3 to 6 moist
Chroma: 3 to 6, dry or moist
Texture: sandy loam, silt loam, loam
Clay content: 18 to 27 percent
Rock fragments: 35 to 80 percent
0 to 70 percent gravel
0 to 80 percent channers
0 to 35 percent cobbles
0 to 40 percent stones
0 to 25 percent flagstones
Pararock fragments: 0 to 20 percent
0 to 20 percent paragravel
0 to 10 percent paracobbles

Bt horizon(s), lower part (or BCt horizon, when present)
Hue: 5YR, 7.5YR, 10YR
Value: 5 to 7 dry, 4 or 5 moist
Chroma: 4 to 6, dry or moist
Texture: loam, silty clay loam, clay loam
Clay content: 20 to 35 percent
Rock fragments: 35 to 90 percent
0 to 45 percent gravel
0 to 45 percent channers
0 to 50 percent cobbles
0 to 35 percent stones
0 to 50 percent flagstones
Pararock fragments: 0 to 75 percent
0 to 75 percent paragravel
0 to 50 percent paracobbles

COMPETING SERIES: These are the Gardellones, Gopheridge, Hurleton, and Oroshore soils. Gardellones soils lack a paralithic contact between 50 and 100 cm and are 100 to 150 cm to a lithic contact of metavolcanic bedrock. Gopheridge soils are 50 to 100 cm to a lithic contact of metavolcanic bedrock. Hurleton soils are 50 to 100 cm to a lithic contact of intrusive igneous rock and have sandy loam and sandy clay loam textures in the lower Bt horizons. Oroshore soils lack a lithic contact between 100 and 150 cm.

GEOGRAPHIC SETTING: The Hetchy soils are on hills and ridges. Slopes range from 3 to 60 percent. These soils formed in colluvium and residuum weathered from phyllite, schist, and other metasedimentary rocks. Elevation is 225 to 1060 meters. The climate is Mediterranean with warm, dry summers and cool, moist winters. The mean annual precipitation is 685 to 1015 mm and the mean annual air temperature is 13 to 16 degrees C. The frost free season is 190 to 315 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Deerflat, Luckymine, Millvilla, and Priestgrade soils. The Deerflat soils are deeper than 150 cm to bedrock and are found on baseslopes. Luckymine and Priestgrade soils are less than 50 cm to bedrock and are on nose slopes and crests. Millvilla soils have less than 35 percent rock fragments in the particle size control section and are on side slopes.

DRAINAGE AND PERMEABILITY: Well drained; saturated hydraulic conductivity is moderately high or high throughout the soil profile.

USE AND VEGETATION: This soil is used for recreation, wildlife habitat, and watershed. Vegetation is interior live oak, blue oak, California foothill pine, Pacific poison oak, whiteleaf manzanita, toyon, buckbrush, chaparral coffeeberry, California yerba santa, and squirreltail.

DISTRIBUTION AND EXTENT: Sierra Nevada Foothills in California; MLRA 18. The series is not extensive.

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

SERIES PROPOSED: Tuolumne County, California, 2018. Source of name from a local reservoir.

REMARKS:
Diagnostic horizons and features recognized in this pedon are:
Ochric Epipedon 0 to 18 cm
Cambic Horizon 4 to 42 cm
Argillic Horizon 42 to 90 cm
Paralithic Contact 90 to 102 cm
Lithic Contact 102 cm
Particle Size Control Section for this pedon: 42 to 90 cm

ADDITIONAL DATA:
NASIS User Pedon ID: 08AMS021
No certified laboratory data exist for this soil.

Soil classified using the 12th Edition of the Keys to Soil Taxonomy.

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National Cooperative Soil Survey
U.S.A.