LOCATION MOTHERLODE              CA

Established Series
CES/TKK/JW
09/2018

MOTHERLODE SERIES

The Motherlode series consists of deep, well drained soils formed in colluvium and residuum weathered from metavolcanic rocks, mainly greenstone and greenschist. Motherlode soils are on hills. Slopes range from 15 to 60 percent. The mean annual precipitation is about 755 mm and the mean annual air temperature is about 16 degrees C.

TAXONOMIC CLASS: Fine-loamy, mixed, active, thermic Ultic Haploxeralfs

TYPICAL PEDON: Motherlode silt loam on a northwest-facing, 42 percent, convex slope under a canopy of blue oak, interior live oak, foothill pine, buckbrush and manzanita at an elevation of 663 meters. (Colors are for dry soil unless otherwise noted. When described on August 3, 2007 the soil was dry throughout).

A--0 to 10 cm; brown (7.5YR 5/4) silt loam, dark brown (7.5YR 3/4) moist; moderate medium granular structure; soft, very friable, slightly sticky, slightly plastic; common very fine roots throughout; common very fine and few fine tubular pores; 5 percent indurated metavolcanic gravel; neutral (pH 6.6); clear smooth boundary. (4 to 13 cm thick)

BA--10 to 25 cm; reddish yellow (5YR 6/6) silt loam, yellowish red (5YR 4/6) moist; weak medium subangular blocky structure; slightly hard, firm, slightly sticky, slightly plastic; few very fine and few fine roots throughout; few very fine and few fine tubular pores; 5 percent indurated metavolcanic gravel; neutral (pH 6.6); clear wavy boundary. (0 to 17 cm thick)

Bt1--25 to 38 cm; reddish yellow (5YR 6/6) gravelly loam, yellowish red (5YR 4/6) moist; moderate medium subangular blocky structure; hard, firm, moderately sticky, moderately plastic; common very fine and few fine roots throughout; common very fine, many fine, and few medium tubular pores; 65 percent prominent clay films on all faces of peds; 15 percent indurated metavolcanics gravel, 5 percent indurated metavolcanic cobbles, 1 percent indurated metavolcanic stones; slightly acid (pH 6.4); clear wavy boundary.

Bt2--38 to 53 cm; reddish yellow (5YR 6/6) very gravelly clay loam, yellowish red (5YR 4/6) moist; moderate medium subangular blocky structure; hard, firm, moderately sticky, moderately plastic; few fine, few medium, and few coarse roots throughout; common very fine, common fine, and few medium tubular pores; 65 percent prominent clay films on all faces of peds; 25 percent indurated metavolcanic gravel, 15 percent indurated metavolcanic cobbles, 1 percent indurated metavolcanic stones; slightly acid (pH 6.4); clear wavy boundary. (Combined thickness of upper Bt horizons is 13 to 65 cm)

Bt3--53 to 81 cm; red (2.5YR 5/8) clay loam, red (2.5YR 4/8) moist; moderate medium subangular blocky structure; hard, firm, moderately sticky, moderately plastic; few very fine, common fine, and few medium roots throughout; few very fine and few fine tubular pores; 65 percent prominent clay films on all faces of peds; 10 percent indurated metavolcanic gravel, 1 percent indurated metavolcanic cobbles; slightly acid (pH 6.2); clear wavy boundary.

Bt4--81 to 97 cm; red (2.5YR 5/8) gravelly clay loam, red (2.5YR 4/8) moist; moderate fine subangular blocky structure; hard, firm, moderately sticky, moderately plastic; common fine, few medium, and few coarse roots throughout; few fine tubular pores; 65 percent prominent clay films on all faces of peds; 20 percent indurated metavolcanic gravel; slightly acid (pH 6.1); clear wavy boundary.

Bt5--97 to 112 cm; reddish yellow (5YR 6/6) very gravelly clay loam, red (2.5YR 4/6) moist; weak medium subangular blocky structure; hard, firm, moderately sticky, moderately plastic; few coarse roots throughout; 65 percent prominent clay films on all faces of peds; 35 percent indurated metavolcanic gravel, 5 percent indurated metavolcanic cobbles; slightly acid (pH 6.1); abrupt irregular boundary. (Combined thickness of lower Bt horizons 30 to 100 cm)

R--112 to 200 cm; very strongly cemented metavolcanic bedrock.

TYPE LOCATION: Tuolumne County, California, about 5.8 km (3.6 miles) west northwest of Moccasin Reservoir Dam, USGS 7.5 minute topographic quadrangle: Moccasin, California; WGS84 37.8258324 latitude and -120.3691711 longitude; UTM Zone 10 731546 meters E 4189748 meters N NAD 83.

RANGE IN CHARACTERISTICS:

Soil temperature: The mean annual soil temperature at 50 cm is 15 to 18 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: 4 to 18 cm
Argillic horizon thickness: 70 to 124 cm
Depth to lithic contact: 100 to 150 cm
Paralithic materials are present above the lithic contact in some pedons.

Reaction: moderately acid to neutral throughout

Particle size control section weighted average:
Rock fragments: 0 to 30 percent, with 0 to 30 percent gravel and 0 to 20 percent cobbles
Clay content: averages 18 to 30 percent clay

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

A horizon
Hue: 5YR, 7.5YR, 10YR
Value: 4 to 6 dry, 3 or 4 moist
Chroma: 3 to 6 dry, 2 to 6 moist
Texture: loam, silt loam
Clay content: 14 to 22 percent
Rock fragments: 0 to 15 percent gravel

BA horizon (where present)
Hue: 5YR, 7.5YR, 10YR
Value: 4 to 6 dry, 3 or 4 moist
Chroma: 3 to 6 dry, 2 to 6 moist
Texture: loam, silt loam
Clay content: 18 to 27 percent
Rock fragments: 0 to 15 percent gravel

Upper Bt horizons
Hue: 2.5YR, 5YR, 7.5YR
Value: 4 to 6 dry, 3 or 4 moist
Chroma: 4 to 6 dry, 3 to 6 moist
Texture: loam, clay loam
Clay content: 18 to 30 percent
Rock fragments: 0 to 45 percent
0 to 25 percent gravel
0 to 20 percent cobbles

Lower Bt horizons
Hue: 2.5YR, 5YR, 7.5YR
Value: 4 to 6, dry or moist
Chroma: 6 to 8 dry, 4 to 8 moist
Texture: clay loam, clay
Clay content: 27 to 50 percent
Rock fragments: 0 to 40 percent
0 to 35 percent gravel
0 to 25 percent cobbles

COMPETING SERIES: These are the Coombs (MLRA 15), Craigsaddle, Deerflat, Flanly, Millvilla, Sierra, Thompsonflat (MLRA 17), Verjeles, Wardsferry, and Yellowlark (MLRA 17) soils. Coombs soils formed in gravelly alluvium and are greater than 200 cm to bedrock. Craigsaddle are 100 to 150 cm to a densic contact and have sandy loam and sandy clay loam textures. Deerflat soils are greater than 150 cm to a paralithic contact. Flanly, Millvilla and Verjeles soils are 50 to 100 cm to a paralithic contact of granodiorite. Sierra soils are greater than 150 cm to a bedrock contact, and have 15 to 25 percent combined coarse and very coarse sand in the Bt horizons. Thompsonflat soils are greater than 150 cm to a bedrock contact and are formed in alluvium. Wardsferry soils are 100 to 150 cm to a paralithic contact composed of metasedimentary rock. Yellowlark soils are have a duripan between 100 and 150 cm and are formed in alluvium.

GEOGRAPHIC SETTING: Motherlode soils are on hills, usually in backslope and footslope hillslope positions. Slopes range from 15 to 60 percent. These soils formed in colluvium and residuum weathered from metavolcanic rocks, mainly greenstone. Elevation is 80 to 800 meters. The climate is Mediterranean with warm, dry summers and cool, moist winters. The mean annual precipitation is 405 to 875 mm and the mean annual air temperature is 14 to 17 degrees C. The frost free season is 215 to 335 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Gardellones, Gopheridge, and Loafercreek soils. The Gardellones and Gopheridge soils have more than 35 percent rock fragments in the particle size control section. Gopheridge and Loafercreek soils have bedrock contact within 50 to 100 cm. All of these soils occur on similar hillslope positions as the Motherlode soils.

DRAINAGE AND PERMEABILITY: Well drained, saturated hydraulic conductivity is moderately high.

USE AND VEGETATION: This soil is used for rangeland, recreation, wildlife habitat, and watershed. Vegetation is blue oak, interior live oak, whiteleaf manzanita, buckbrush, and poison oak.

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

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

SERIES PROPOSED: Calaveras County, California. The name is a term used to describe the region of the Sierra Nevada Mountains in California that is famous for its gold deposits.

REMARKS:
Diagnostic horizons and features recognized in this pedon are:
Ochric Epipedon 0 to 25 cm
Argillic Horizon 25 to 112 cm
Lithic Contact 112 cm
Particle Size Control Section for this pedon: 25 to 75 cm

ADDITIONAL DATA:
NASIS User Pedon ID: 07CA630RJV134
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.