Established Series


The Dubakella series consists of moderately deep, well drained soils that formed in material weathered from ultrabasic rocks with a large amount of serpentinitic minerals. Dubakella soils are on mountains. Slopes are 5 to 75 percent. Mean annual precipitation is about 30 inches and mean annual temperature is about 50 degrees F.

TAXONOMIC CLASS: Clayey-skeletal, magnesic, mesic Mollic Haploxeralfs

TYPICAL PEDON: Dubakella stony loam--on a northeast facing slope of 21 percent under Jeffrey pine, sugar pine, incense cedar, buckwheat and iris at 4,000 feet elevation. (Colors are for dry soil unless otherwise stated. When described August 7, 1958, the soil was dry to 11 inches and slightly moist 11 to 21 inches.)

Oi--2 inches to 0; fresh, partly decomposed and decomposed pine needles; abrupt smooth boundary. (1 to 3 inches thick).

A1--0 to 2 inches; reddish brown (5YR 4/4) stony loam, dark reddish brown (5YR 3/4) moist; strong fine and medium subangular blocky structure; soft, friable, nonsticky and nonplastic; many very fine roots; many very fine and fine interstitial pores; about 30 percent stones, cobbles and pebbles; neutral (pH 7.0); abrupt smooth boundary. (2 to 4 inches thick).

A2--2 to 11 inches; reddish brown (5YR 4/4) stony clay loam, dark reddish brown (5YR 3/4) moist; moderate medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; many very fine and fine and common medium roots; many very fine and fine pores; about 20 percent stones, cobbles and pebbles, pebbles are weathered subangular fragments of serpentinized rock; neutral (pH 7.0); gradual irregular boundary. (6 to 12 inches thick).

Bt--11 to 21 inches; yellowish brown (10YR 5/4) very gravelly clay, dark yellowish brown (10YR 4/4) moist; strong medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; common very fine and fine, and few medium roots; many very fine and fine pores; few thin discontinuous clay films; about 35 percent rock fragments, pebbles are angular and less weathered than above; neutral (pH 7.0); clear irregular boundary. (6 to 26 inches thick).

C--21 to 25 inches; blue green, hard, fractured and partly weathered serpentinized rock; cracks filled with soil material similar to that in Bt horizon with moderately thick, nearly continuous clay films and dark coatings in fractures. (0 to 6 inches thick).

R--25 to 30 inches; serpentinized bedrock.

TYPE LOCATION: Tehama County, California; about 35 miles west of Red Bluff and 0.8 miles northeast of Tedoc Gap; 500 feet from Tedoc Mt. Road junction; 1,300 feet northeast of the southwest corner NW1/4 section 28, T.28 N., R.9 W.

RANGE IN CHARACTERISTICS: The thickness of the A and Bt horizons is 14 to 28 inches. Depth to a lithic contact is 20 to 40 inches. The mean annual soil temperature is 47 to 52 degrees F. The soil is usually moist but is dry from mid May until October. Reaction is neutral or mildly alkaline.

The A horizon color is 10YR 3/3, 4/3, 5/3, 5/4, 6/3; 7.5YR 2.5/2, 3/4, 4/2, 4/4, 5/2, 5/4; 5YR 3/3, 3/4, 4/3, 4/4, 5/3, 5/4. Moist color is 10YR 3/2, 3/3, 3/4, 4/2, 4/3, 4/4; 7.5YR 2.5/2, 3/2, 3/4, 4/2, 4/4; 5YR 3/2, 3/3, 3/4, 4/2, 4/3, 4/4 value of 3 and chroma of 2 or 3 moist are only in the upper part of the A horizon. It is loam or clay loam modified by rock fragments. It typically has granular or subangular blocky structure but some pedons have platy structure in the upper part. Organic matter content is 10 percent in the upper part and 4 percent in the lower part of the A horizon. Some pedons have an AB horizon. Rock fragments consist of stones, cobbles and gravel and range from 20 to 50 percent.

The Bt horizon color is 10YR 3/3, 3/4, 4/3, 4/4, 5/3, 5/4; 7.5YR 3/4, 4/2, 4/4, 5/2, 5/4, 6/4; 5YR 3/4, 3/3, 4/3, 4/4, 5/3, 5/4, 4/6, 5/6. Moist color is 10YR 3/3, 3/4, 4/3, 4/4; 7.5YR 3/4, 4/4; 5YR 3/3, 3/4, 4/3, 4/4. It is clay loam or clay and has 30 to 50 percent clay but averages 35 to 50 percent clay. It has angular blocky subangular blocky or prismatic structure. Base saturation is greater than 75 percent by sum of cations. Cobbles and pebbles range from 35 to 75 percent.

COMPETING SERIES: There are no other soils in this family.

GEOGRAPHIC SETTING: Dubakella soils are on mountains. Slopes are 5 to 75 percent. The soil formed in materials weathered from serpentine or serpentinitic bedrock. Elevations are 2,200 to 4,100 feet. In some areas as much as 50 percent of the surface is covered by cobbles or stones. Rock outcrops are also common. The climate is subhumid with warm to hot dry summers and cold moist winters. Mean annual precipitation is 20 to 60 inches. Some precipitation occurs as snow on the higher ridges and in more northern areas. Seasonal snowfall ranges from a few inches to about 24 inches. In the high winter rainfall interior mountains of southwestern Oregon, the mean annual precipitation may range to 100 inches. Mean annual temperature is 45 to 52 degrees F.; mean January temperature is about 32 degrees F.; mean July temperature is about 65 degrees F. Frost-free season averages about 90 to 200 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Marpa, and Sheetiron soils. Marpa, and Sheetiron soils lack magnesic mineralogy.

DRAINAGE AND PERMEABILITY: Well drained; medium to very high runoff; slow permeability.

USE AND VEGETATION: Used for timber production, watershed or wildlife. Dominant vegetation is open stands of conifers, mostly Jeffrey pine with sugar pine, Douglas-fir and incense cedar. Also, there are buckbrush, grasses, and forbs.

DISTRIBUTION AND EXTENT: Mountainous areas in northern and central California and southwestern Oregon. The soils are moderately extensive. MLRA 5, 15 and 22.

REMARKS: Soils mapped as Dubakella at the family level in MLRA 22 should be reevaluated as new series. Soils previously included with Dubakella with soil temperatures of 53 to 59 degrees are now excluded from the series concept.

Diagnostic horizons and features recognized in this pedon are:

Ochric epipedon--the zone from the surface to a depth of about 11 inches (A1, A2).

Argillic horizon--the zone from about 11 to 21 inches (Bt).

Particle-size control section--the zone from about 11 to 21 inches (Bt).

ADDITIONAL DATA: NSSL pedon S68CA-057-036 (variant)


SERIES ESTABLISHED: Soil-Vegetation survey of Mendocino County, California, 1952.

National Cooperative Soil Survey