LOCATION PRIESTGRADE             CA

Established Series
MJE/AGB/TKK/JW
10/2018

PRIESTGRADE SERIES

The Priestgrade series consists of shallow soils formed from colluvium over residuum from metasedimentary rocks such as phyllite, argillite, schist or slate. The Priestgrade soils are on backslopes, shoulders and summits of high hills, ridges and canyons. Slopes range from 8 to 90 percent. The mean annual precipitation is about 725 mm and the mean annual air temperature is about 15 degrees C.

TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, thermic Lithic Mollic Haploxeralfs

TYPICAL PEDON: Priestgrade loam on an east-northeast facing, convex, 73 percent slope at an elevation of 546 meters; under cover of interior live oak, toyon, Pacific poison oak, annual grasses and forbs. (Colors are for dry soils unless otherwise noted. When described on July 17th, 2007 the soil was dry throughout.)

A1--0 to 8 cm; brown (7.5YR 5/3) loam, dark brown (7.5YR 3/3) moist; moderate medium granular structure; slightly hard, friable, slightly sticky, slightly plastic; common very fine roots throughout; common very fine tubular and few fine tubular pores; 5 percent angular strongly cemented phyllite channers; moderately acid (pH 5.7); clear smooth boundary.

A2--8 to 18 cm; brown (7.5YR 5/3) loam, dark brown (7.5YR 3/3) moist; weak medium subangular blocky structure; slightly hard, friable, slightly sticky, slightly plastic; common very fine and few fine roots throughout; few very fine and fine tubular pores; 10 percent angular strongly cemented phyllite channers; strongly acid (pH 5.5); clear wavy boundary. (combined thickness of A horizons is 6 to 25 cm)

Bt1--18 to 36 cm; brown (7.5YR 5/4) channery loam, dark brown (7.5YR 3/4) moist; weak medium subangular blocky structure; slightly hard, friable, slightly sticky, slightly plastic; common fine and medium roots throughout; few very fine and fine tubular pores; 3 percent faint clay films on all faces of peds; 30 percent angular strongly cemented phyllite channers; very strongly acid (pH 5.0); clear wavy boundary.

Bt2--36 to 48 cm; strong brown (7.5YR 4/6) extremely flaggy loam, reddish brown (5YR 4/4) moist; weak medium subangular blocky structure; slightly hard, friable, slightly sticky, slightly plastic; common fine and few medium roots between rock fragments; 2 percent faint clay films on surfaces along pores, 2 percent distinct clay films on rock fragments and 3 percent faint clay films on all faces of peds; 45 percent angular strongly cemented phyllite flagstones; 20 percent angular strongly cemented phyllite stones; very strongly acid (pH 4.9); abrupt irregular boundary. (combined thickness of Bt horizons is 13 to 35 cm)

R--48 to 200 cm; very strongly cemented phyllite bedrock, fractured at intervals of 10 to <45 cm.

TYPE LOCATION: Tuolumne County, California, on the north side of Don Pedro Reservoir, approximately 1.8 km (1.1 miles) south-southeast of the summit of Hog Mountain; USGS Topographic Quadrangle: Moccasin, California. WGS84 37.868004 latitude and -120.346565 longitude; UTM Zone 10 733403 meters E 4194489 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):
Argillic horizon thickness: 10 to 40 cm
Depth to lithic contact: 25 to 50 cm

Organic matter: averages greater than 1.2 percent (0.7 percent organic carbon) in the upper 10 cm of the A horizon(s)

Particle size control section weighted average:
Rock fragments: 0 to 85 percent
0 to 70 percent channers
0 to 50 percent flagstones
0 to 30 percent stones
Clay content: 18 to 27 percent

A horizons
Hue: 10YR, 7.5YR
Value: 2.5 to 6 dry, 2 to 3 moist
Chroma: 2 to 4 dry or moist
Texture: loam, silt loam
Clay content: 10 to 20 percent
Rock fragments: 5 to 60 percent
Reaction: very strongly acid to slightly acid

Bt horizons
Hue: 7.5YR, 10YR, 5YR
Value: 3 to 6 dry, 2 to 5 moist
Chroma: 3 to 6 dry or moist
Texture: loam, silty clay loam, sandy clay loam
Clay content: 15 to 30 percent
Rock fragments: 35 to 85 percent (predominantly flat; channers or flagstones)
Reaction: extremely acid to moderately acid

COMPETING SERIES: These are the Pardee and Stineway soils. Pardee soils are on eroded fan remnants and have indurated, rounded, rock fragments of alluvial origin over residuum from volcanic tuff or conglomerate. Stineway soils are neutral to moderately alkaline.

GEOGRAPHIC SETTING: The Priestgrade soils are on shoulders, summits and backslopes of ridges, high hills and canyons in the Central Sierra Nevada foothills. Slopes range from 8 to 90 percent. These soils formed in colluvium over residuum from metasedimentary rocks. Elevation is 250 to 950 meters. The climate is Mediterranean with warm, dry summers and cool, moist winters. The mean annual precipitation is 650 to 975 mm and the mean annual air temperature is 13 to 16 degrees C. The frost free season is 180 to 320 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Copperopolis, Deerflat, Moccasinhill and Sanguinetti soils. Copperopolis soils lack argillic horizons and occur in similar landscape positions. Moccasinhill soils are moderately deep to a lithic contact of metasedimentary rock and occur on backslopes of hills and canyons. Deerflat soils have less than 35 percent rock fragments in the particle-size control section and are greater than 150 cm to a bedrock contact. Sanguinetti soils are 100 to 150 cm to a lithic contact. Deerflat and Sanguinetti soils are on footslopes and lower backslopes.

DRAINAGE AND PERMEABILITY: Well to somewhat excessively drained. Saturated hydraulic conductivity of the soil is moderately high throughout. Saturated hydraulic conductivity of the bedrock is low to high.

USE AND VEGETATION: This soil is used for recreation, wildlife habitat, and watershed. Vegetation is California black oak, California foothill pine, Interior live oak, Canyon live oak, Pacific poison oak, whiteleaf manzanita and toyon. On droughty south-facing slopes the vegetation may be dominated by chamise and deerbrush.

DISTRIBUTION AND EXTENT: Sierra Nevada Foothills of California; MLRA 18. The series is moderately extensive.

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

SERIES ESTABLISHED: Tuolumne County, California. Source of name is Old Priest Grade, a road near the unincorporated community of Moccasin.

REMARKS:
Particle Size Control Section for this pedon: 36 to 48 cm
Diagnostic horizons and features recognized in this pedon are:
Umbric epipedon 0 to 18 cm
Argillic horizon 36 to 48 cm
Lithic contact 48 cm

ADDITIONAL DATA:
Pedon information for this type location only:
NASIS User Pedon ID: 07RJV053
Pedon Purpose: soil survey inventory

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.