LOCATION LASCO CAEstablished Series
TAXONOMIC CLASS: Coarse-loamy, mixed, superactive, frigid Ultic Haploxeralfs
TYPICAL PEDON: Lasco gravelly sandy loam, forested, on a 36 percent west-facing slope under mixed conifers and shrubs at 5,400 feet elevation. (When described September 13, 1984, the soil was dry throughout and the soil temperature at 20 inches was 45 degrees F. Colors are for dry soil unless otherwise noted).
Oi--2 to 0 inches; fresh and decomposed pine needles, twigs, cones and bark; abrupt wavy boundary.
A--0 to 2 inches; brown (7.5YR 5/2) gravelly sandy loam, dark brown (7.5YR 3/2) moist; moderate fine and medium granular structure; soft, very friable, nonsticky and slightly plastic; many very fine and fine roots; many very fine interstitial pores; 15 percent 5 to 75 mm pebbles and 10 percent 2 to 5 mm pebbles; slightly acid (pH 6.5); clear wavy boundary. (2 to 6 inches thick)
BA--2 to 9 inches; pinkish gray (7.5YR 6/2) gravelly sandy loam, brown (7.5YR 4/2) moist; moderate medium subangular blocky structure; slightly hard, very friable, nonsticky and slightly plastic; common very fine, many fine, common medium and few coarse roots; 15 percent 5 to 75 mm pebbles and 10 percent 2 to 5 mm pebbles; slightly acid (pH 6.5); clear wavy boundary. (0 to 9 inches thick)
Bt1--9 to 28 inches; light brown (7.5YR 6/4) gravelly sandy loam, brown (7.5YR 4/4) moist; moderate medium subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; common very fine, fine and medium roots; many very fine and common fine interstitial pores; common thin clay films on peds; 15 percent 5 to 75 mm pebbles and 10 percent 2 to 5 mm pebbles; slightly acid (pH 6.5); clear wavy boundary.
Bt2--28 to 49 inches; brownish yellow (10YR 6/6) gravelly sandy loam, dark yellowish brown (10YR 4/6) moist; moderate medium and coarse angular blocky structure; hard, very friable, slightly sticky and slightly plastic; few very fine, fine and medium roots; many very fine and common fine interstitial pores; many moderately thick clay films on peds and bridging mineral grains; 15 percent 5 to 75 mm pebbles and 10 percent 2 to 5 mm pebbles; slightly acid (pH 6.5); clear wavy boundary. (the combined thickness of the Bt horizons is 28 to 42 inches).
Crt--49 to 60 inches; light brownish gray (2.5Y 6/2) soft weathered granite, dark grayish brown (2.5Y 4/2) moist; few very fine and fine roots in fissures; no pores; many thick light brown (7.5YR 6/4) clay films, brown (7.5YR 4/4) moist, on fracture planes; dug by spade with difficulty; neutral (pH 7.0).
TYPE LOCATION: Lassen County, California; about 4.7 miles E of Westwood on HWY 36, across McKenzie Meadows on trail and continue on Beaty and Associates road 2232 to its intersection with road 2230, 2.5 miles N on road 2230 and 100 feet upslope; about 300 feet E and 1,400 feet N of the SW corner of section 24, T.29 N., R.9 E.
RANGE IN CHARACTERISTICS: The mean annual soil temperature varies from 44 to 46 degrees F. The depth to the paralithic contact is 40 to 60 inches. The moisture control section (12 to 37 inches) is dry from August 1 to November 1 (90 days) and is moist in some or all parts the rest of the time. The soil temperature exceeds 41 degrees F from May 1 to December 1 and exceeds 47 degrees F from June 1 to November 1. Base saturation ranges from 30 to 50 percent.
The A horizon dry color is 7.5YR 5/2; 10YR 5/2 or 5/3. Moist color is 7.5YR 3/2 or 10YR 3/2. It is sandy loam, gravelly loam, gravelly sandy loam or gravelly loamy coarse sand with 5 to 12 percent clay and 5 to 35 percent gravel.
The BA horizon dry color is 7.5YR 6/2, 6/6 or 10YR 5/4. Moist color is 7.5YR 4/2, 4/6 or 10YR 3/4. It is sandy loam or gravelly sandy loam modified by 5 to 35 percent gravel.
The Bt horizon dry color is 7.5YR 6/4, 6/6, 7/4, 7/6; 10YR 6/6 or 7/4. Moist color is 7.5YR 4/4, 4/6, 5/4, 5/6; 10YR 4/6 or 5/4. It is sandy loam or gravelly sandy loam with 10 to 18 percent clay and 5 to 35 percent gravel. The clay increase from the A to Bt horizon is 3 to 6 percent (absolute) within a distance of 6 to 10 inches.
COMPETING SERIES: This is the Jabu series. Jabu soils have lithologic discontinuities in the B horizon and a weakly expressed fragipan.
GEOGRAPHIC SETTING: Lasco soils are on mountain back slopes. Slopes are 2 to 50 percent. The soils formed in residuum and colluvium weathered from granite. Elevation is 5,000 to 7,000 feet. The climate is subhumid with warm dry summers and cold moist winters. The mean annual precipitation is about 25 to 35 inches with 40 to 120 inches of snow. The mean annual temperature is about 44 degrees F., mean January temperature is about 26 degrees F. and mean July temperature is about 60 degrees F. The frost-free season is 60 to 80 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Almanor, Baileycreek, Quartzburg, Swainow, Toiyabe and Weste soils. Baileycreek and Weste soils are loamy-skeletal and moderately deep. Almanor soils are medial-skeletal and lack an argillic horizon. Quartzburg soils are shallow and skeletal. Swainow soils are loamy-skeletal and have a mantle of ash. Toiyabe soils are shallow.
DRAINAGE AND PERMEABILITY: Well drained; runoff is slow through rapid; moderately rapid permeability.
USE AND VEGETATION: Lasco soils are used for timber production. The vegetation is Jeffrey pine, Douglas-fir, white fir, Incense-cedar, sugar pine, whitethorn ceanothus, golden chinkapin and squawcarpet.
DISTRIBUTION AND EXTENT: Northwestern Lassen County near Westwood, California. The soils of this series are moderately extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Lassen County, California, Susanville Area, Parts of Lassen and Plumas Counties Soil Survey Area, 1988.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon: The zone from the mineral soil surface to a depth of 9 inches (A and BA horizons).
Argillic horizon: The zone from 9 to 49 inches (Bt1 and Bt2 horizons).
Last revised by the state on 4/88.