LOCATION SUMMERTOWN CAEstablished Series
TAXONOMIC CLASS: Ashy-skeletal, glassy, frigid Humic Vitrixerands
TYPICAL PEDON: Summertown, gravelly ashy loamy coarse sand on a west-facing (292 degrees) slope of 20 percent, under a cover of white fir, greenleaf manzanita, Jeffrey pine and bush chinquapin at an elevation of 5992 feet, (1826 m). When described on 6/25/07, the soil was dry throughout. (Colors are for dry soil unless otherwise noted).
Oi--0 to 2 inches (0 to 5 cm); slightly decomposed needles, cones, and twig litter; abrupt smooth boundary.
Oa--2 to 4 inches (5 to 9 cm); highly decomposed needles, cones and twig litter; common very fine and fine roots; abrupt wavy boundary.
A--4 to 6 inches (9 to 14 cm); dark grayish brown (10YR 4/2) gravelly ashy loamy coarse sand, very dark brown (10YR 2/2) moist; 2 percent clay; weak very thick platy structure; loose, nonsticky, nonplastic; common very fine, many fine and medium, and few coarse and very coarse roots; many very fine and fine interstitial and common fine tubular pores; 10 percent subangular fine gravel, 3 percent subangular medium and coarse gravel, and 3 percent subangular stones; moderately acid, pH 5.7 by Hellige-Truog; NaF pH 10.8; abrupt wavy boundary. (1 to 4 inches (2 to 10 cm) thick)
AB--6 to 15 inches (14 to 38 cm); brown (10YR 5/3) cobbly ashy loamy coarse sand, dark brown (10YR 3/3) moist; 2 percent clay; weak very fine to medium subangular blocky structure parting to single grain; loose, nonsticky, nonplastic; many very fine to coarse and few very coarse roots; many very fine and fine interstitial and few fine and medium tubular pores; 11 percent subangular fine gravel, 5 percent subangular medium and coarse gravel, 5 percent subangular cobbles, and 3 percent subangular stones; neutral, pH 6.7 by Hellige-Truog; NaF pH 10.9; clear wavy boundary. (7 to 11 inches (18 to 28 cm) thick)
2Bw1--15 to 22 inches (38 to 55 cm); dark yellowish brown (10YR 4/4) very cobbly ashy loamy coarse sand, dark brown (10YR 3/3) moist; 2 percent clay; weak fine subangular blocky structure parting to single grain; loose, nonsticky, nonplastic; many very fine to coarse and few very coarse roots; many very fine and fine interstitial and few fine and medium tubular pores; 6 percent subangular fine gravel, 4 percent subangular medium and coarse gravel, 25 percent subangular cobbles and 15 percent subangular stones; slightly acid, pH 6.5 by Hellige-Truog; NaF pH 10.9; clear wavy boundary.
2Bw2--22 to 31 inches (55 to 80 cm); yellowish brown (10YR 5/4) extremely cobbly ashy loamy sand, dark brown (10YR 3/3) moist; 4 percent clay; single grain; loose, nonsticky, nonplastic; common very fine to coarse and few very coarse roots; many very fine and fine interstitial pores; 6 percent subangular fine gravel, 8 percent subangular medium and coarse gravel, 40 percent subangular cobbles, and 20 percent subangular stones; slightly acid, pH 6.3 by Hellige-Truog; NaF pH 10.6; abrupt wavy boundary. (Combined thickness of the 2Bw horizon is 14 to 18 inches (36 to 46 cm) thick)
2Cdq--31 to 43 inches (80 to 108 cm); very pale brown (10YR 7/3) extremely stony ashy loamy coarse sand, dark yellowish brown (10YR 4/4) moist; 2 percent clay; massive; very hard, firm, nonsticky, nonplastic; few very fine interstitial pores; 20 percent silica masses around rock fragments; 5 percent subangular fine gravel, 8 percent subangular medium and coarse gravel, 40 percent subangular cobbles, and 30 percent subangular stones; slightly acid, pH 6.5 by Hellige-Truog; NaF pH 10.7. (10 to 14 inches (25 to 36 cm) thick)
TYPE LOCATION: Shasta County, California, about 0.66 miles southeast of Manzanita Lake, approximately 300 feet east and 1600 feet south of the northwest corner of sec 20, T. 21 N, R. 4 E, 40 degrees, 31 minutes, 29 seconds north latitude and 121 degrees, 33 minutes, 28 seconds west longitude, NAD83; USGS Quad: Manzanita Lake, California.
RANGE IN CHARACTERISTICS:
Depth to restrictive feature: Densic contact 20 to 40 inches (51 to 102 cm).
Mean annual soil temperature: 45 to 47 degrees F (7 to 8 degrees C).
Soil moisture control section is dry: July to October (about 90 days).
Particle-size control section (thickest part): 4 percent clay, and 74 percent rock fragments.
Surface fragments: 2 to 20 percent gravel, 1 to 5 percent cobbles, 1 to 3 percent stones, and 1 to 3 percent boulders.
A horizon:
Color dry: 10YR 4/2, 2.5Y 4/2, 5/2
Color moist: 10YR 2/1, 2/2, 3/1
Texture: gravelly ashy loamy coarse sand, ashy fine sandy loam, ashy sandy loam, gravelly ashy fine sandy loam, very gravelly ashy sandy loam, very cobbly ashy sandy loam
Clay content: 2 to 4 percent
Rock fragments: 5 to 15 percent fine gravel, 2 to 20 percent medium and coarse gravel, 5 to 35 percent total gravel, 0 to 20 percent cobbles, 0 to 5 percent stones, 0 to 3 percent boulders, 7 to 55 percent total rock fragments
Organic matter: 4 to 5.5 percent
Acid oxalate extractable Al plus 1/2 Fe: 0.55 to 0.70
P retention: 30 to 50 percent
Glass content: 30 to 35 percent
NaF pH: 9.0 to 11.3
Soil reaction: moderately acid or slightly acid
AB horizon:
Color dry: 10YR 5/3
Color moist: 10YR 3/3
Texture: gravelly ashy loamy coarse sand, ashy fine sandy loam, cobbly ashy loamy coarse sand.
Clay content: 2 to 4 percent
Rock fragments: 2 to 15 percent fine gravel, 1 to 5 percent medium and coarse gravel, 4 to 15 percent total gravel, 2 to 10 percent cobbles, 2 to 10 percent stones, 0 to 3 percent boulders, 10 to 30 percent total rock fragments
Organic matter: 2 to 3 percent
Acid oxalate extractable Al plus 1/2 Fe: 0.8 to 0.95
P retention: 45 to 60 percent
Glass content: 30 to 40 percent
NaF pH: 11.0 to 11.5
Soil reaction: slightly acid or neutral
2Bw horizon:
Color dry: 10YR 4/4, 5/4, 6/3, 6/4, 2.5Y 5/3, 6/3
Color moist: 10YR 3/2, 3/3, 4/2, 4/4, 5/4
Texture: very stony ashy loamy coarse sand, extremely cobbly ashy loamy sand, very stony ashy fine sandy loam, very gravelly ashy loamy fine sand, very bouldery ashy fine sandy loam, very cobbly ashy loamy coarse sand
Clay content: 2 to 6 percent
Rock fragments: 5 to 15 percent fine gravel, 4 to 25 percent medium and coarse gravel, 10 to 35 percent total gravel, 5 to 40 percent cobbles, 0 to 20 percent stones, 0 to 20 percent boulders, 35 to 80 percent total rock fragments
Organic matter: 2.5 to 4 percent
Acid oxalate extractable Al plus 1/2 Fe: 1.2 to 1.5
P retention: 55 to 70 percent
Glass content: 30 to 40 percent
NaF pH: 10.5 to 11.2
Soil reaction: slightly acid
2Cdq horizon:
Color dry: 10YR 6/2, 7/3, 7/4, 8/3
Color moist: 10YR 4/4, 5/4
Texture: extremely stony ashy loamy coarse sand, extremely gravelly ashy loamy sand, extremely stony ashy loamy sand
Clay content: 2 to 5 percent
Rock fragments: 5 to 15 percent fine gravel, 5 to 25 percent medium and coarse gravel, 10 to 40 percent total gravel, 15 to 40 percent cobbles, 5 to 45 percent stones, 0 to 20 percent boulders, 60 to 88 percent total rock fragments
Organic matter: 0 to 1.5 percent
Acid oxalate extractable Al plus 1/2 Fe: 2.0 to 2.8
P retention: 70 to 85
Glass content: 30 to 40 percent
NaF pH: 10.0 to 11.0
Soil reaction: slightly acid
COMPETING SERIES: These are the Fryear, McCumber, Pipp, Silentcone and Yapoah soils. The Fryear and Silentcone soils are moderately deep to bedrock. The McCumber and Yapoah soils are very deep. The Pipp soils are deep to bedrock.
GEOGRAPHIC SETTING: Summertown soils are on moraines that are Till of Raker Peak age, 27,000 to 35,000 years old. Slopes are 5 to 35 percent. These soils formed in volcanic ash over and mixed with till derived from volcanic rocks. Elevation is 5704 to 6803 feet (1739 to 2074 m). Mean annual precipitation is 39 to 65 inches (991 to 1651 mm). Mean annual temperature is 43 to 45 degrees F (6 to 7 degrees C).
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Chaos and Sueredo soils. Chaos are very deep and formed in rockfall avalanche deposits. Sueredo is very deep and formed in younger till.
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Well drained; saturated hydraulic conductivity is high in the A, AB and 2Bw horizons, and moderately low in the 2Cdq horizon.
USE AND VEGETATION: This soil is used for wildlife habitat, recreation, ecosystem management and watershed. Vegetation is white fir, Jeffrey pine, greenleaf manzanita, snowbrush ceanothus and bush chinquapin.
DISTRIBUTION AND EXTENT: These soils are inextensive and are mapped in MLRA: 22B, Southern Cascade Mountains.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Shasta County California 2009. Source of name from a historical site north of Manzanita Lake.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Umbric epipedon: 4 to 15 inches, (9 to 38 cm)
Andic soil properties: 4 to 31 inches, (9 to 108 cm)
Densic Contact: 31 inches, (80 cm)
Particle-size control section: 4 to 31 inches (9 to 79 cm)
Soil moisture control section: 134 to 32 inches (33 to 80 cm)
ADDITIONAL DATA: Characterization data from lab pedon number 08N0486, NSSL, Lincoln NE. NASIS User Pedon ID in Davis, MLRA Office: 789237.