LOCATION LONGVAL CAEstablished Series
TAXONOMIC CLASS: Ashy-skeletal, glassy Humic Xeric Vitricryands
TYPICAL PEDON: Longval gravelly ashy fine sandy loam--forestland. (Colors are for dry soil unless otherwise noted).
Oi--0 to 1 inch; very dark grayish brown (10YR 3/2) slightly decomposed organic matter consisting of needles and leaves very dark brown (10YR 2/2) moist; moderate thick platy structure; soft, very friable, nonsticky and nonplastic; few very fine roots; many very fine to medium interstitial pores; strongly water repellent, more than 60 seconds to adsorb a bead of water on the surface; 5 percent gravel; moderately acid (pH 6.0); abrupt smooth boundary (.25 to 2.5 inches thick)
A1--1 to 7 inches; dark grayish brown (10YR 4/2) gravelly ashy fine sandy loam, very dark brown (10YR 2/2) moist; moderate very fine and fine subangular blocky structure; soft, very friable, nonsticky and nonplastic; many very fine through medium roots; many very fine interstitial pores; 5 percent cobbles; 25 percent volcanic gravel; moderately acid (pH 6.0); abrupt smooth boundary. (3 to 6 inches thick)
A2--7 to 15 inches; brown (10YR 4/3) gravelly ashy fine sandy loam, very dark brown (10YR 2/2) moist; weak fine and medium subangular blocky structure; soft, very friable, nonsticky and nonplastic; many very fine through coarse roots; many very fine interstitial pores; 1 percent cobbles; 25 percent volcanic gravel; moderately acid (pH 6.0); clear wavy boundary. (5 to 12 inches thick.)
AB--15 to 32 inches; brown (10YR 4/3) very cobbly ashy fine sandy loam, very dark grayish brown (10YR 3/2) moist; weak coarse subangular blocky structure; slightly hard, very friable, nonsticky and nonplastic; many very fine, common medium through coarse roots; many very fine interstitial pores; 10 percent stones; 25 percent cobbles; 20 percent volcanic gravel; moderately acid (pH 6.0); clear wavy boundary. (9 to 21 inches thick.)
C1--32 to 43 inches; brown (10YR 5/3) very cobbly ashy fine sandy loam, very dark grayish brown (10YR 3/2) moist; massive; slightly hard, very friable, nonsticky and nonplastic; many very fine, many fine through medium, and few coarse roots; many very fine tubular pores; 5 percent stones, 15 percent cobbles, 30 percent volcanic gravel; moderately acid (pH 6.0); clear wavy boundary. (9 to 21 inches thick.)
C2--43 to 60 inches; yellowish brown (10YR 5/4) very stony ashy fine sandy loam, dark brown (10YR 3/3) moist; massive; slightly hard, very friable, nonsticky and nonplastic; common very fine through medium roots; many very fine tubular pores; 10 percent stones, 10 percent cobbles and 30 percent gravel; moderately acid (pH 6.0).
TYPE LOCATION: Lassen County, California; on the Modoc National Forest about 2 miles southwest of Lost Lake; about 1900 feet east and 1800 feet south of the northwest corner of section 28, T. 38 N., R. 16 E.; USGS Emerson Peak 7.5 minute topographic quadrangle; approximately 41 degrees 08 minutes 08 seconds north latitude and 120 degrees 10 minutes 6.4 seconds west longitude, NAD27.
RANGE IN CHARACTERISTICS:
Soil moisture - These soils are usually moist in winter, spring, and early summer, dry later in summer and fall; Xeric moisture regime.
Mean annual soil temperature - 39 to 44 degrees F.
Mean summer soil temperature 44 to 49 degrees F.
Mollic epipedon thickness 20 to 40 inches; C horizons that meet the color requirement, do not have sufficient organic matter to meet the requirements of mollic epipedons.
Oxalate Al + 1/2 oxalate iron: 0.4 to 0.8 percent.
Sodium Fluoride pH: 9.5 to 11.0 throughout
Volcanic glass content - 50 to 80 percent in the coarse silt through fine sand fractions.
Profile reaction - Moderately acid or slightly acid.
Particle-size control section - Clay content: 5 to 12 percent.
Rock fragments: Averages 40 to 60 percent, mainly gravel and cobbles. Lithology of fragments is volcanic rock such as tuff, andesite, or basalt.
A horizon - Hue: 10YR or 7.5YR.
Value: 3 or 4 dry, 2 or 3 moist.
Chroma: 2 or 3, dry or moist.
Base saturation: 50 to 85 percent.
Organic matter content: 1 to 4 percent.
AB horizon - Hue: 10YR or 7.5YR.
Value: 4 or 5 dry, 3 or 4 moist.
Chroma: 2 through 4, dry or moist.
Rock Fragments: 40 to 60 percent, mainly cobbles and gravel.
Texture: ashy fine sandy loam.
C horizon - Hue: 10YR or 7.5YR.
Value: 4 or 5 dry, 3 or 4 moist.
Chroma: 2 through 4, dry or moist.
Structure: Massive.
Rock fragments: 40 to 60 percent, mainly cobbles and stones.
COMPETING SERIES: These are the Bagmont and Lotawaca series. Bagmont and Lotawaca soils have soft bedrock at less than 60 inches.
GEOGRAPHIC SETTING: Longval soils are on mountain toe slopes. They formed in glacial outwash and alluvium derived from tuff, andesite, or basalt and volcanic ash. Slopes are 2 to 30percent. Elevations range from 6,170 to 8,500 feet. The climate is subhumid with cold, moist winters and cool, dry summers. The mean annual precipitation is 20 to 30 inches most of which comes as snow. The mean annual temperature is 39 to 41 degrees F. The frost-free period is 40 to 60 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Lyonman, Paynepeakand Pyropatti soils. Lyonman soils have argillic horizons and are moderately deep to paralithic contacts. Paynepeak and Pyropatti soils have bedrock at 40 to 60 inches.
DRAINAGE AND PERMEABILITY: Well drained; low or medium surface runoff; moderately rapid permeability.
USE AND VEGETATION: Longval soils are used for wildlife habitat and as a source of wood products. The vegetation consists primarily of lodgepole pine and scattered whitebark pine with an understory that is dominated by subalpine big sagebrush, western needlegrass, Columbia needlegrass, bluegrass, and dryland sedge.
DISTRIBUTION AND EXTENT: Northeastern California. These soils are not extensive with about 4,300 acres of the series mapped to date. MLRA 21.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California.
SERIES ESTABLISHED: Surprise Valley-Home Camp Area, Modoc and Lassen Counties, California and Washoe County, Nevada, 1971.
REMARKS: In January 2004 the taxonomic class was updated from Coarse-loamy, mixed, superactive Vitrandic Dystrocryepts. The isotic mineralogy class, volcanic glass content, and oxalate aluminum plus one-half iron values are estimated based on properties of similar soils in major land resource area 21. Future study is needed to verify the isotic mineralogy class and the vitrandic intergrade features.
December 2004, redescribed a profile near the original location and changed the classification from Coarse-loamy, isotic Vitrandic Dystrocryepts to Ashy-skeletal, glassy Humic Xeric Vitricryands. This revision is based on current field mapping to better represent the soil as mapped.
Earlier authors and editors of the OSD include: LNL/LWW/SBJ/JVC.
Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - The zone from the soil surface to 32 inches (A1,A2 and AB horizons).
Andic soil properties - The soil material with high volcanic glass content and acid oxalate extractable Al and Fe more than .4 extends from the mineral soil surface to 60 inches (A1 A2, AB, C1 and C2 horizons).
Particle-size control section - The zone from the mineral soil surface to 40 inches (A1, A2, AB and part of the C1 horizons).