LOCATION CONWAYRIDGE CAEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, frigid Vitrandic Argixerolls
TYPICAL PEDON: Conwayridge extremely gravelly ashy loam--rangeland. (Colors are for dry soil unless otherwise noted.) The soil surface is covered with 50 percent gravel, 15 percent cobbles, 5 percent stones, and 5 percent boulders.
A--0 to 4 inches; grayish brown (10YR 5/2) extremely gravelly ashy loam, very dark grayish brown (10YR 3/2) moist; moderate medium platy structure; slightly hard, very friable, slightly sticky and slightly plastic; common very fine roots; common very fine vesicular pores; 55 percent gravel, 15 percent cobbles, and 10 percent stones; neutral; clear wavy boundary. (3 to 5 inches thick)
Bt--4 to 11 inches; brown (10YR 5/3) extremely gravelly ashy loam, dark brown (10YR 3/3) moist; moderate fine subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; many very fine, many fine, and common medium roots; common very fine tubular and interstitial pores; few faint clay bridges between sand grains; 60 percent gravel and 10 percent cobbles; neutral; clear wavy boundary. (7 to 9 inches thick)
2Bq1--11 to 22 inches; pale brown (10YR 6/3) extremely cobbly sandy loam, brown (10YR 4/3) moist; weak fine subangular blocky structure; soft, very friable, slightly sticky and slightly plastic; common very fine, common fine, and common medium roots; common very fine tubular and interstitial pores; 5 percent opal coats on sand grains; 25 percent gravel, 45 percent cobbles, and 15 percent stones; neutral; clear wavy boundary. (6 to 12 inches thick)
2Bq2--22 to 37 inches; pale brown (10YR 6/3) extremely cobbly sandy loam, brown (10YR 4/3) moist; weak fine subangular blocky structure; soft, very friable, slightly sticky and nonplastic; common very fine and fine roots; common very fine tubular and interstitial pores; 5 percent opal coats on sand grains; 25 percent gravel, 45 percent cobbles, and 15 percent stones; neutral; clear wavy boundary. (10 to 17 inches thick)
2Bq3--37 to 53 inches; light yellowish brown (2.5Y 6/4) extremely cobbly sandy loam, olive brown (2.5Y 4/4) moist; massive; hard, very friable, nonsticky and nonplastic; few very fine and fine roots; common very fine tubular and interstitial pores; 25 percent thin iron-manganese coats on bottom of rock fragments; 10 percent opal bridges on sand grains and 0.5 to 2 mm thick opal coats on bottoms of rock fragments; 45 percent gravel, 15 percent cobbles, and 10 percent stones; neutral; clear wavy boundary. (10 to 20 inches thick)
2Bq4--53 to 63 inches; light yellowish brown (2.5Y 6/4) extremely gravelly sandy loam, olive brown (2.5Y 4/4) moist; massive; slightly hard, very friable, nonsticky and nonplastic; few very fine, fine and medium roots; common very fine interstitial and few very fine tubular pores; 50 percent iron-manganese coats on the bottoms of rock fragments; 10 percent opal coats on bottom of rock fragments; 60 percent gravel and 15 percent cobbles; neutral.
TYPE LOCATION: Mono County, California; about 1.9 miles southwest of Conway Summit and 100 feet east of the Toiyabe National Forest boundary; approximately 2,600 feet south and 100 feet east of the northwest corner of section 34, T. 3 N., R. 25 E.; USGS Lundy 7.5 minute topographic quadrangle; 38 degrees 04 minutes 36.4 seconds north latitude and 119 degrees 12 minutes 44.2 seconds west longitude, NAD27.
RANGE IN CHARACTERISTICS:
Soil moisture - Usually moist in the moisture control section during late fall, winter, and spring; dry from mid-July through September for 60 to 80 consecutive days in the four months following the summer solstice; Typic xeric moisture regime.
Mean annual soil temperature - 44 to 47 degrees F.
Mean summer soil temperature - 59 to 68 degrees F.
Mean winter soil temperature - 32 to 36 degrees F.
Mollic epipedon thickness - 10 to 14 inches, includes the Bt horizon.
Depth to bedrock - More than 80 inches.
Particle-size control section - Clay content: Averages 10 to 18 percent; Rock fragments: Averages 60 to 85 percent, mainly gravel and cobbles. Lithology of fragments are mixed igneous and metamorphic rocks such as granodiorite, andesite, schist, and gneiss.
A horizons - Value: 4 or 5 dry, 2 or 3 moist.
Chroma: 2 or 3, dry or moist.
Organic matter content: 1 to 3 percent.
Reaction: Slightly acid or neutral.
Volcanic glass content: 15 to 30 percent in coarse silt through fine sand fractions.
Bt horizon - Chroma: 2 or 3, dry or moist.
Texture: Extremely gravelly ashy loam or extremely cobbly ashy sandy loam.
Clay content: 10 to 18 percent.
Rock fragments: 60 to 85 percent.
Organic matter content: 1 to 3 percent.
Reaction: Slightly acid or neutral.
Volcanic glass content: 15 to 30 percent in coarse silt through fine sand fractions.
2Bq horizons - Hue: 10YR or 2.5Y.
Value: 6 or 7 dry, 4 or 5 moist.
Chroma: 2 through 4, dry or moist.
Texture: Extremely gravelly sandy loam or extremely cobbly sandy loam.
Clay content: 8 to 15 percent.
Rock fragments: 60 to 85 percent.
Reaction: Slightly acid or neutral.
Secondary silica: 5 to 15 percent as 0.5 to 2 mm thick coats on the bottom of rock fragments or as bridges between sand grains.
COMPETING SERIES: These are the Ginserly (T), Imnaha, Loganvalley (T), Masonic, Needhill, Roundbarn, Saturday, Skullhollow (T), and Wilt series.
Ginserly, Needhill, and Saturday soils are deep to lithic contacts. Imnaha, Skullhollow, and Wilt soils are moderately deep to lithic contacts. Masonic soils are moderately deep to paralithic contacts. Loganvalley soils have 20 to 35 percent clay in the particle-size control section and have argillic horizons that are 10 to 20 inches thick. Roundbarn soils are deep to paralithic contacts.
GEOGRAPHIC SETTING: Conwayridge soils are on moraines. They typically occur on summit and shoulder positions. They formed in till derived from igneous and metamorphic rocks such as granodiorite, andesite, schist, and gneiss with surficial additions of eolian volcanic ash. The probable sources of the volcanic ash are the Mono Craters and Long Valley Caldera in eastern California. Slopes are 8 to 30 percent. Elevations range from 8,000 to 9,500 feet. The climate is subhumid-continental with cold, moist winters and warm, dry summers. The mean annual precipitation is 30 to 40 inches, the mean annual temperature is 36 to 39 degrees F., and the frost-free period is 40 to 60 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Aspetill and Dunderberg soils. Aspetill and Dunderberg soils have mollic epipedons more than 16 inches thick.
DRAINAGE AND PERMEABILITY: Well drained; low surface runoff; moderately rapid permeability (high saturated hydraulic conductivity).
USE AND VEGETATION: Conwayridge soils are used for rangeland, recreation, watershed, and wildlife habitat. The native vegetation is mainly low sagebrush, pine needlegrass, prairie junegrass, and sedge.
DISTRIBUTION AND EXTENT: Eastern California, on the east side of the Sierra Nevada Range. These soils are not extensive with about 800 acres of the series mapped to date. MLRA 22A.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Mono County (Toiyabe National Forest Area), California, 2006.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - The zone from the soil surface to 11 inches (A and Bt horizons).
Argillic horizon - The zone from 4 to 11 inches (Bt horizon).
Vitrandic intergrade feature - The zone from the soil surface to 11 inches (A and Bt horizons).
Particle-size control section - The zone from 4 to 11 inches (Bt horizon).
ADDITIONAL DATA: Volcanic glass content determined locally by optical grain counts using a polarizing petrographic microscope.