LOCATION MERCERCAVE CA

Established Series
DWB/AJP/TKK/JW
09/2018

MERCERCAVE SERIES

The Mercercave series consists of deep, well drained soils formed in colluvium over residuum derived from marble. The Mercercave soils are on shoulders and backslopes of hills. Slopes range from 3 to 60 percent. The mean annual precipitation is about 955 mm and the mean annual air temperature is about 15 degrees C.

TAXONOMIC CLASS: Clayey-skeletal, mixed, active, mesic Typic Rhodoxeralfs

TYPICAL PEDON: Mercercave gravelly loam on a north-facing, 18 percent, linear slope, under canyon live oak, black oak, ponderosa pine, and toyon at an elevation of 666 meters. (Colors are for dry soils unless otherwise noted. When described on October 8, 2008 the soil was moist throughout.)

A--0 to 9 cm; brown (7.5YR 4/4) gravelly loam, dark brown (7.5YR 3/2) moist; weak fine subangular blocky parting to moderate fine granular structure; soft, very friable, nonsticky, nonplastic; many very fine roots; many medium irregular pores; 20 percent subrounded indurated marble gravel; slightly acid (pH 6.1); abrupt smooth boundary. (3 to 20 cm thick)

BA--9 to 33 cm; brown (7.5YR 4/4) very stony loam, dark reddish brown (5YR 3/3) moist; weak fine subangular block parting to moderate fine granular structure; soft, friable, slightly sticky, nonplastic; many very fine roots; common fine and medium tubular and common medium irregular pores; 10 percent subrounded indurated marble gravel, 5 percent subrounded indurated marble cobbles, 40 percent subrounded indurated marble stones; slightly acid (pH 6.1); abrupt smooth boundary. (Combined thickness of A and BA horizon is 25 to 50 cm thick)

Bt1--33 to 45 cm; reddish brown (5YR 4/4) very stony clay loam, dark reddish brown (5YR 3/4) moist; moderate fine subangular blocky structure; slightly hard, friable, slightly sticky, slightly plastic; common very fine and few fine roots; many fine and medium tubular and common very fine tubular pores; 30 percent faint clay films on vertical faces of peds; 10 percent subrounded indurated marble gravel, 40 percent subrounded indurated marble stones; moderately acid (pH 6.0); clear smooth boundary.

Bt2--45 to 110 cm; reddish brown (5YR 4/4) extremely stony clay loam, dark reddish brown (2.5YR 3/4) moist; moderate fine and medium subangular blocky structure; hard, firm, moderately sticky, moderately plastic; few fine to coarse roots and few very coarse roots; common very fine, fine, and medium tubular pores; 40 percent prominent clay films on vertical faces of peds; 10 percent subrounded indurated marble gravel, 70 percent subrounded indurated marble stones; slightly acid (pH 6.4); gradual smooth boundary. (Combined thickness of the Bt1 and Bt2 horizons is 50 to 100 cm thick)

Bt3--110 to 140 cm; reddish brown (2.5YR 4/4) very stony clay, dark reddish brown (2.5YR 3/4) moist; moderate fine and medium subangular blocky structure; very hard, very firm, moderately sticky, moderately plastic; few fine and medium roots; few very fine to medium tubular pores; 60 percent prominent clay films on vertical faces of peds; 10 percent subrounded indurated marble gravel, 25 percent subrounded indurated marble stones; slightly acid (pH 6.2); abrupt wavy boundary. (0 to 50 cm thick)

R--140 to 200 cm; indurated marble bedrock; strong effervescence, by HCL, 1 normal.

TYPE LOCATION: Calaveras County, California, about 1.6 km (1 mile) northwest of the town of Murphys, CA, USGS 7.5 minute topographic quadrangle: Murphys, California; WGS84 38.150890 latitude and -120.476585 longitude; UTM Zone 10 721111 meters E 4225565 meters N NAD83.

RANGE IN CHARACTERISTICS:
Soil temperature: The mean annual soil temperature at 50 cm is 8 to 15 degrees C and the difference between mean summer and mean winter soil temperature is greater than 6 degrees C. The soils have a mesic temperature regime.

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

Diagnostic Feature(s):
Mollic epipedon thickness: 25 to 50 cm
Argillic horizon thickness: 45 to 140 cm
Depth to lithic contact: 100 to 150 cm

Organic matter: 1 to 6 percent in the epipedon.

Reaction: slightly acid to neutral in the epipedon (6.1-7.3) and moderately acid to neutral in the control section (5.6-7.3).

Base saturation: less than 50 percent directly above the lithic contact (by ammonium acetate).

Particle size control section weighted average:
Rock fragments: 35 to 80 percent, with 5 to 15 percent gravel, 0 to 35 percent cobbles, and 20 to 65 percent stones.
Clay content: averages 35 to 50 percent clay

A horizon
Hue: 7.5YR or 5YR
Value: 3 to 5 dry, 2 or 3 moist
Chroma: 2 to 4 dry, 1 to 3 moist
Organic matter: 1 to 6 percent
Texture: loam or clay loam
Clay content: 15 to 35 percent
Rock fragments: 0 to 20 percent
0 to 20 percent gravel
0 to 5 percent cobbles
0 to 5 percent stones

BA horizon
Hue: 7.5YR or 5YR
Value: 4 or 5 dry, 2 or 3 moist
Chroma: 2 to 4 dry, 2 to 4 moist
Organic matter: 1 to 2 percent
Texture: loam or clay loam
Clay content: 15 to 40 percent
Rock fragments: 5 to 60 percent
0 to 20 percent gravel
0 to 10 percent cobbles
0 to 40 percent stones

Bt1 and Bt2 horizon
Hue: 2.5YR or 5R
Value: 3 or 4 dry, 3 moist
Chroma: 4 to 6 dry, 4 to 6 moist
Organic matter: 0.5 to 1.5 percent
Texture: sandy clay loam, clay loam, silty clay loam, silty clay, sandy clay, or clay
Clay content: 35 to 50 percent
Rock fragments: 35 to 65 percent
0 to 25 percent gravel
0 to 40 percent cobbles
0 to 50 percent stones

Bt3 horizon (when present)
Hue: 5YR, 2.5YR, or 5R
Value: 3 or 4 dry, 3 or 4 moist
Chroma: 4 to 6 dry, 4 to 6 moist
Organic matter: 0.25 to 0.75 percent
Texture: sandy clay loam, clay loam, silty clay loam, or clay
Clay content: 27 to 50 percent
Rock fragments: 35 to 85 percent
0 to 25 percent gravel
0 to 50 percent cobbles
0 to 70 percent stones

COMPETING SERIES: There are no other series in this family at this time.

GEOGRAPHIC SETTING: The Mercercave soils are on shoulders and backslopes of hills. Slopes range from 3 to 60 percent. These soils formed in colluvium over residuum derived from marble. Elevation is 535 to 775 meters. The climate is Mediterranean with warm, dry summers and cool, moist winters. The mean annual precipitation is 875 to 1090 mm and the mean annual air temperature is 14 to 15 degrees C. The frost free season is 220 to 260 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Tiger Creek, Nedsgulch, Beybek, and Aquariusmine soils. The Tiger Creek and Nedsgulch soils are fine-loamy. Tiger Creek typically occupies lower hillslope positions and interfluve areas. Nedsgulch soils develop from schist, phyllite, and other similar metasedimentary rocks. Beybek and Aquariusmine soils are thermic and occupy lower elevations and warm aspects. Beybek soils are moderately deep to lithic contact and Aquariusmine soils are fine-loamy.

DRAINAGE AND PERMEABILITY: Well drained, moderately low to high saturated hydraulic conductivity in the control section. Saturated hydraulic conductivity of the bedrock is low to very high.

USE AND VEGETATION: This soil is used for recreation and wildlife habitat. Vegetation is intermixed conifers and hardwoods. Tree species include black oak, live oak, and ponderosa pine. Understory composition is primarily native shrubs with few grasses and forbs. Understory species include poison oak, toyon, buckthorn, and manzanita.

DISTRIBUTION AND EXTENT: Sierra Nevada Mountains of California; MLRA 22. This series is not extensive.

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

SERIES PROPOSED: Calaveras County, California, 2008. Source of the name comes from the Mercer Caverns, a cave near the location where this soil originated.

REMARKS:
Some pedons were described with a thin Oi horizon composed of slightly decomposed pine needles, twigs, and other plant detritus.

Diagnostic horizons and features recognized in this pedon are:
Mollic Epipedon 0 to 33 cm (A, BA, and Bt1 horizon)
Argillic Horizon 45 to 140 cm (Bt2 and Bt3 horizon)
Lithic Contact 140 to 200 cm (R horizon)
Particle Size Control Section for this pedon: 45 to 95 cm.

ADDITIONAL DATA:
NASIS User Pedon ID: 09DWB001

No certified laboratory data exists for this soil.

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

National Cooperative Soil Survey
U.S.A.