LOCATION TYSON              CA 
Established Series


The Tyson series consists of moderately deep, well drained soils formed in material weathered from sedimentary rocks. Tyson soils are on hills and mountains and have slopes of 9 to 75 percent. The mean annual precipitation is about 50 inches and the mean annual temperature is about 50 degrees F.

TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, mesic Humic Dystroxerepts

TYPICAL PEDON: Tyson very gravelly loam - on an east-facing slope of 42 percent under a canopy of Brewer oak at 3,880 feet elevation. (Colors are for dry soil unless otherwise noted. When described on July 24, 1979, the soil was dry throughout).

Oi--1 inch to 0; oak leaves and twigs.

A--0 to 7 inches; brown (10YR 5/3) very gravelly loam, very dark grayish brown (10YR 3/2) moist; moderate fine, medium, and coarse granular structure; soft, very friable, nonsticky and slightly plastic; common very fine roots; many very fine interstitial and common very fine tubular pores; 35 percent pebbles and 5 percent 75 to 150 mm cobbles; slightly acid (pH 6.5); clear smooth boundary.

AB--7 to 13 inches; yellowish brown (10YR 5/4) gravelly loam, dark brown (10YR 3/3) moist; moderate fine and medium subangular blocky structure; soft, friable, slightly sticky and slightly plastic; common very fine and fine roots; many very fine and few fine tubular pores; 25 percent 2 to 15 mm pebbles; strongly acid (pH 5.5); abrupt smooth boundary. (Combined thickness of the A horizon is 8 to 20 inches)

Bw--13 to 24 inches; pale brown (10YR 6/3) very gravelly loam, dark brown (10YR 3/3) moist; moderate medium subangular blocky structure; soft, friable, slightly sticky and slightly plastic; common very fine, fine and medium roots; many very fine and few fine tubular pores; 50 percent 2 to 35 mm pebbles; very strongly acid (pH 4.5); abrupt smooth boundary. (10 to 30 inches thick)

R--24 inches; fractured shale with fractures 1/8 inches apart.

TYPE LOCATION: Mendocino County, California; about 9 air miles east of Covelo, on Etsel Ridge, 0.5 miles southeast of intersection of Etsel Ridge Road (Mendocino NF Road 1N02) and Mexico Ridge Road (23N18), then 150 feet east of forest road 1N02, over ridgetop and downslope; 2,400 feet south and 1,700 feet west of northeast corner of section 9, T.22 N., R.11 W., MDBM.

RANGE IN CHARACTERISTICS: Thickness of the solum and depth to a lithic contact is 20 to 40 inches. The soil between the depths of 5 and 15 inches is dry in all parts from June to October and is moist in all parts from November to May. The mean annual soil temperature is 49 to 55 degrees F. Base saturation (ammonium acetate) is less than 50 percent in some part. Organic matter ranges from 1 to 10 percent.

The A horizon is 10YR 3/3, 4/1, 4/2, 4/3, 5/2, 5/3; 2.5Y 4/1, 4/2, 5/2, or 5/3. Moist color is 10YR 2/1, 2/2, 3/1, 3/2, 3/3; 2.5Y 2/2, 3/2, or 3/3. The A horizon is gravelly or very gravelly loam with 18 to 27 percent clay and 20 to 60 percent coarse fragments. It is neutral through moderately acid and becomes more acid with depth. Base saturation (sum) ranges from 45 to 85 percent. The AB horizon, where present, has higher chroma, and is more acid with lower base saturation than the A horizon.

The Bw horizon is 10YR 5/3, 5/4, 6/2, 6/3, 6/4; 2.5Y 5/2, 5/4, or 6/4. Moist color is 10YR 3/2, 3/3, 3/4, 4/2, 4/3, 4/4, 5/4; 2.5Y 4/2, or 4/4. It is very gravelly or very cobbly loam or clay loam with 20 to 30 percent clay and 35 to 60 percent coarse fragments. It is moderately acid through very strongly acid. Base saturation (ammonium acetate) ranges from 40 to 60 percent.

COMPETING SERIES: These are the Coyata (OR), Decy (CA), Musty (OR), and Ovall (WA) series. Coyata soils have hue of 7.5YR or 5YR and are dry for 60 days or less. Decy soils have base saturation less than 40 percent throughout. Musty and Ovall soils are dry 60 to 90 days and Ovall soils average less than 18 percent clay.

GEOGRAPHIC SETTING: Tyson soils are on ridgetops and sideslopes of hills and mountains and have slopes of 9 to 75 percent. They formed in material weathered from sandstone, shale, or their slightly metamorphosed equivalents. Elevations are 2,000 to 5,000 feet. The climate is subhumid with hot dry summers and cool moist winters. Mean annual precipitation is 40 to 70 inches, with about 10 to 30 inches of snow. Mean January temperature is 40 degrees F; mean July temperature is 70 degrees F; mean annual temperature is 47 to 56 degrees F. Frost-free period ranges from 110 to 250 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Bluenose, Neuns, Shortyork, Updegraff and Witherell soils. Bluenose and Updegraff soils are more than 40 inches deep. Neuns soils lack umbric epipedons. Shortyork soils are thermic.

DRAINAGE AND PERMEABILITY: Well drained; medium to very rapid runoff; moderate permeability.

USE AND VEGETATION: Used for firewood production, watershed and wildlife habitat. Vegetation is mainly Brewer oak and Oregon white oak with scattered Douglas-fir, California black oak and Ponderosa pine.

DISTRIBUTION AND EXTENT: Northern California in the Coast Range. The soils are moderately extensive.


SERIES ESTABLISHED: Mendocino County, California 1952. MLRA 5.

REMARKS: Diagnostic horizons and features recognized in this pedon are:

Umbric epipedon - the zone from 0 to 13 inches (A, AB horizons)

Cambic horizon - the zone from 13 to 24 inches (Bw horizon)

Tyson soils were formerly classified as loamy-skeletal, mixed, mesic Ultic Haploxerolls. Further investigation in Lake and Mendocino counties found that base saturation (ammonium acetate) was less than 50 percent. The Tyson soil as published in the Mendocino National Forest Area report has base saturation (ammonium acetate) less than 50 percent, but appears to be Pachic and would be outside the series as now defined.

National Cooperative Soil Survey