LOCATION SOUTHPAC CA

Established Series
Rev. KJO-SJB-DJE
12/2022

SOUTHPAC SERIES

The Southpac series consists of very deep, well drained soils formed in material weathered from andesite. Southpac soils are on mountain or plateau back slopes. Slopes range from 2 to 50 percent. The mean annual precipitation is about 25 inches and the mean annual temperature is about 50 degrees F.

TAXONOMIC CLASS: Loamy-skeletal, isotic, mesic Vitrandic Haploxeralfs

TYPICAL PEDON: Southpac very stony loam, forested, on a 16 percent SE facing slope under mixed confers and shrubs at 5,200 feet elevation. The surface is covered with 25 percent stones. When described, September 13, 1985, the soil was moist to 8 inches and dry below. (Colors are for dry soil unless otherwise noted.)

Oi--2 to 0 inches; fresh and decomposing litter of needles, twigs and cones; abrupt wavy boundary.

A--0 to 7 inches; reddish brown (5YR 4/3) very stony loam, dark reddish brown (5YR 3/3) moist; weak fine and medium granular structure; soft, very friable, slightly sticky and slightly plastic; many very fine and fine, and common medium roots; common fine and medium tubular pores; 25 percent 5 to 75 mm pebbles and 10 percent 2 to 5 mm pebbles; slightly acid (pH 6.5); clear wavy boundary. (4 to 8 inches thick)

BAt--7 to 12 inches; brown (7.5YR 5/4) very gravelly loam, dark reddish brown (5YR 3/4) moist; moderate fine and medium subangular blocky structure; soft, very friable, slightly sticky and plastic; common fine and medium roots; common fine tubular pores; common moderately thick clay films on peds and in pores; 20 percent 5 to 75 mm pebbles and 15 percent 2 to 5 mm pebbles; slightly acid (pH 6.3); clear wavy boundary. (4 to 10 inches thick)

Bt1--12 to 23 inches; reddish brown (5YR 4/4) very gravelly loam, dark reddish brown (5YR 3/4) moist; moderate medium subangular blocky structure; hard, very friable, sticky and plastic; common fine and medium and coarse roots; few fine tubular and interstitial pores; many moderately thick clay films on peds; 30 percent 5 to 75 mm pebbles and 10 percent 2 to 5 mm pebbles; slightly acid (pH 6.1); clear wavy boundary.

Bt2--23 to 35 inches; reddish brown (5YR 4/4) very gravelly loam, dark reddish brown (5YR 3/4) moist; strong medium subangular blocky structure; hard, very friable, sticky and plastic; few fine, common medium and few coarse roots; common fine and few medium tubular pores; many moderately thick clay films on peds; 20 percent 5 to 75 mm pebbles and 20 percent 2 to 5 mm pebbles; slightly acid (pH 6.1); abrupt wavy boundary. (The combined thickness of the Bt1 and Bt2 horizons is 12 to 29 inches.)

Bt3--35 to 61 inches; reddish brown (5YR 5/3) gravelly clay loam, dark reddish brown (5YR 3/3) moist; strong fine and medium angular blocky structure; hard, friable, sticky and plastic; few very fine medium and coarse roots; common very fine tubular pores; many moderately thick clay films on peds and in pores; 10 percent 5 to 75 mm pebbles and 10 percent 2 to 5 mm pebbles; slightly acid (pH 6.1).

TYPE LOCATION: Lassen County, California; about 3.5 miles NW of Susanville; 0.5 miles N of second left fork on the old Paul Bunyan Logging Road N of Paiute Creek; about 800 feet N and 2 100 feet W of the SE corner of section 22, T.30 N., R.11 E.

RANGE IN CHARACTERISTICS: The mean annual soil temperature varies from 47 to 52 degrees F. The soil moisture control section (10 to 30 inches) is dry from July 15th to November 1st (107 days) and is moist in all parts from December 1st to May 15th. The soil temperature exceeds 41 degrees F from April 15th to December 1st and exceeds 47 degrees F from May 15th to November 15th. Particle-size control section averages 20 to 27 percent clay. Rock fragments on the surface and within the A horizon range from 15 to 25 percent stones, 5 to 30 percent cobbles and 15 to 35 percent gravel. Base saturation ranges from 60 to 75 percent. Clay content increases with depth.

The A horizon dry color is 7.5YR 4/4, 5/2, 5/4; 5YR 4/3 or 5/3. Moist color is 7.5YR 3/2; 5YR 3/3 or 3/4. Reaction is slightly acid or neutral.

The BAt horizon dry color is 7.5YR 4/4 or 5/4. Moist color is 5YR 3/3, 3/4 or 4/4. Texture is very gravelly loam or very cobbly loam with 15 to 18 percent clay. Rock fragments range from 40 to 55 percent.

The Bt1 and Bt2 horizons dry colors are 5YR 4/4, 5/4 or 6/4. Moist color is 5YR 3/3, 3/4 or 4/4. Texture is very gravelly loam, very cobbly loam or very stony loam with 20 to 27 percent clay. Rock fragments range from 35 to 50 percent.

The Bt3 horizon is 5YR 4/3, 5/3 or 6/4. Moist color is 5YR 3/3, 3/4 or 4/4. Texture is gravelly clay loam or cobbly clay loam with 27 to 30 percent clay. Rock fragments range from 20 to 30 percent.

COMPETING SERIES: These are the Bamtush, Bottlerock, Janscel and Kinkle series. Bamtush soils have a mean annual soil temperature of 53 to 58 degrees F and the soil temperature never falls below 41 degrees F. Bottlerock soils have a mean annual soil temperature of 53 to 58 degrees F and have obsidian fragments and are dominated by amorphous properties. Janscel soils have a mean annual soil temperature of 52 to 59 degrees F. Kinkle soils have less than 18 percent clay in the control section.

GEOGRAPHIC SETTING: Southpac soils are on back slopes of plateaus or mountains. Slopes range from 9 to 50 percent. These soils formed in material weathered from andesite. Elevation is 4,600 to 5,400 feet. The climate is subhumid with warm dry summers and cold moist winters. The mean annual precipitation is about 20 to 30 inches with 40 to 70 inches of snow. The mean annual temperature is about 50 degrees F., mean July temperature is about 66 degrees F and mean January temperature is about 26 degrees F. The frost-free season is 80 to 100 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Gavel and Ulhalf soils. Ulhalf soils are fine-loamy. Gavel soils are 20 to 40 inches deep to bedrock.

DRAINAGE AND PERMEABILITY: Well drained, runoff is medium or rapid; moderately slow permeability.

USE AND VEGETATION: Southpac soils are used for timber production. Vegetation is Jeffrey pine, incense-cedar, sugar pine, white fir, antelope bitterbrush and prostrate ceanothus.

DISTRIBUTION AND EXTENT: Northwestern Lassen County near Susanville, Ca. The soils of this series are not extensive.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California

SERIES PROPOSED: Lassen County, California, Susanville Area, parts of Lassen and Plumas County, 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 7 inches (A horizon)

Argillic horizon - the zone from about 12 to 61 inches (Bt1, Bt2 and Bt3 horizons).

Major Diagnostic Soil Characteristics:

Ultic Subgroup: 60 to 75 percent base saturation (using Baileycreek and Gavel as benchmark soils.)

Last revised by the state on 2/91.

National Cooperative Soil Survey
U.S.A.