LOCATION LAVATOP CAEstablished Series
TAXONOMIC CLASS: Medial-skeletal, amorphic, mesic Humic Haploxerands
TYPICAL PEDON: Lavatop gravelly medial fine sandy loam on a south facing 2 percent slope under a cover of greenleaf manzanita, ponderosa pine and California black oak at an elevation of 4210 feet, (1283 m). When described on 6/19/95 the soil was moist throughout. (Colors are for dry soil unless otherwise noted).
Oi--0 to 0.5 inches, (0 to 1.27 cm); pine needles, leaves, cones, and twig litter.
A--0.5 to 3.5 inches, (1.27 to 9 cm); dark brown (10YR 3/3) gravelly medial fine sandy loam, very dark grayish brown (10YR 3/2) moist; 18 percent clay; weak very fine subangular blocky structure; loose, very friable, nonsticky and nonplastic; many fine and medium, and few very fine roots; many very fine irregular pores; noneffervescent; 25 percent subangular basalt gravel; strongly acid, pH 5.5 by pH meter 1:1 water; NaF pH 10.6; clear smooth boundary. (3 to 11 inches, (8 to 28 cm) thick)
Bw1--3.5 to 15.5 inches, (9 to 41 cm); brown (10YR 4/3) very gravelly medial sandy loam, very dark grayish brown (10YR 3/2) moist; 20 percent clay; weak very fine subangular blocky structure; loose, very friable, nonsticky and slightly plastic; many fine and medium, and few coarse and very coarse roots; many very fine irregular pores; noneffervescent; 40 percent subangular basalt gravel; strongly acid, pH 5.4 by pH meter 1:1 water; NaF pH 10.9; clear smooth boundary.
Bw2--15.5 to 25.5 inches, (41 to 66 cm); dark yellowish brown (10YR 4/4) extremely gravelly medial sandy loam, dark brown (10YR 3/3) moist; 18 percent clay; weak very fine subangular blocky structure; loose, very friable, nonsticky and slightly plastic; many medium roots; many very fine irregular pores; noneffervescent; 30 percent subangular basalt gravel and 50 percent subangular basalt cobbles; strongly acid, pH by 5.3 by pH meter 1:1 water; NaF pH 10.6; abrupt smooth boundary. (Combined thickness of the Bw horizon is 20 to 29 inches, (51 to 74 cm) thick).
R--25.5 inches, (66 cm); fractured indurated basalt.
TYPE LOCATION: Butte County, California; about 6.1 miles east of Camp Eighteen, approximately 1250 feet east and 250 feet north of the southwest corner Section 36, Township 21 N., Range 7 E., 39 degrees, 37 minutes, 45.8 seconds, North latitude and 121 degrees, 8 minutes, 54 seconds West longitude, NAD27. U.S.G.S. Quad: Cascade, California.
RANGE IN CHARACTERISTICS: Depth to lithic bedrock is 20 to 40 inches, (51 to 102 cm). The mean annual soil temperature is 47 to 54 degrees F, (11 to 12 degrees C). The soil moisture control section is dry in all parts from about July to about October (about 90 days). The particle-size control section averages 18 to 20 percent clay and 45 to 60 percent rock fragments, mostly gravel and cobbles. Mineralogy is amorphic. Base saturation by ammonium acetate ranges from 9 to 23 percent to a depth of 25.5 inches, (66 cm). CEC by ammonium acetate ranges from 36 to 40 to a depth of 25.5 inches, (66 cm). Acid Oxalate extractable Al plus 1/2 Fe ranges from 2.9 to 3.7 to a depth of 25.5 inches, (66 cm). P retention ranges from 85 to 96 to a depth of 25.5 inches, (66 cm). Rock fragments on the surface range from 5 to 30 percent gravel, 0 to 40 percent cobbles and 0 to 30 percent stones.
The A horizon dry color is 10YR 3/3. Moist color is 10YR 3/2. Texture is dominantly gravelly medial fine sandy loam, but in some pedons is extremely gravelly medial fine sandy loam, extremely cobbly medial fine sandy loam, medial loam or gravelly medial loam. Clay content ranges from 18 to 20 percent. Rock fragments range from 10 to 40 percent gravel and 0 to 40 percent cobbles. Organic matter ranges from 10 to 15 percent. NaF pH ranges from 10.5 to 11.0. Reaction ranges from strongly acid to moderately acid.
The Bw horizon dry color is 10YR 4/3 or 4/4. Moist color is 10YR 3/2, 3/3 or 4/2. Texture is very gravelly medial sandy loam, extremely gravelly medial sandy loam, extremely cobbly medial sandy loam or extremely stony medial fine sandy loam. Clay content ranges from 18 to 20 percent. Rock fragments range from 30 to 40 percent gravel, 0 to 50 percent cobbles, 0 to 35 percent stones and 0 to 25 percent boulders. Organic matter ranges from 5 to 12 percent. NaF pH ranges from 10.5 to 11.0. Reaction is strongly acid.
COMPETING SERIES: These are the Shakeridge and Timberisland soils. Shakeridge soils are very deep to lithic basalt. Timberisland soils are deep to lithic basalt.
GEOGRAPHIC SETTING: Lavatop soils are on ridgetops and sideslopes on volcanic Sierra Nevada mountains. Slopes range from 0 to 30 percent. These soils formed in mixed tephra and gravelly residuum from Lovejoy basalt. Elevation is 3200 to 4800 feet, (975 to 1585 m). Mean annual precipitation is 75 to 80 inches, (1905 to 2032 mm). The mean annual temperature is 50 to 52 degrees F, (10 to 11 degrees C). Frost free season is 110 to 140 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Lumpkin, Shakeridge, and Timberisland soils. Lumpkin soils are shallow to lithic basalt. Shakeridge soils are on sideslopes and are very deep to lithic basalt. Timberisland soils are deep to lithic basalt.
DRAINAGE AND PERMEABILITY: Well drained; high runoff; moderately rapid saturated hydraulic conductivity in the A and Bw horizons.
USE AND VEGETATION: This soil is used for timber production, wildlife habitat and watershed. Vegetation is greenleaf manzanita, California black oak, ponderosa pine, incense cedar, California hazel, Pacific dogwood, Douglas-fir, common snowberry, princes pine, whitevein shinleaf, deerbrush, sugar pine, whiteleaf manzanita and some white fir.
DISTRIBUTION AND EXTENT: Butte and Plumas Counties, California and occur on the Upper Batholith and Volcanic Flows subsection of the Sierra Nevada section. MLRA 22A - Sierra Nevada Range. The soils are not extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Butte County, California 2005. Source of name from Lavatop on the Cascade quad.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Umbric epipedon - zone from 0.5 to 25.5 inches, (1.27 to 66 cm) (A, Bw1, Bw2)
Andic soil properties zone from 0.5 to 25.5 inches.
Lithic contact- the zone from 25.5 inches, (66 cm) (R)
Particle-size control section - zone from 0.5 to 25.5 inches, (1.27 to 66 cm).
Soil moisture control section - zone from 17 to 25.5 inches, (43 to 66 cm).
Assume bulk density is 1.0 g/cc or less to a depth of 15.5 inches, (41 cm).
ADDITIONAL DATA: Reference samples from lab pedon number: 96P0135, NSSL, Lincoln, NE.