LOCATION CREFORK CAEstablished Series
TAXONOMIC CLASS: Fine, smectitic, mesic Typic Palexeralfs
TYPICAL PEDON: Crefork clay loam--on a northeast-facing convex-concave slope of 17 percent under Oregon white oak, star thistle, and buckbrush at an elevation of 2,700 feet. (Colors are for dry soil unless otherwise stated. When described the soil was nearly dry to about 6 inches, and slightly moist below).
The soil surface is partially covered with 5 percent pebbles and scattered leaves and grass stems.
A--0 to 5 inches; brown (10YR 5/3) clay loam, dark grayish brown (10YR 4/2) moist; weak medium and fine subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; common fine and very fine roots; common very fine tubular pores; 5 percent gravel; slightly acid (pH 6.5); abrupt wavy boundary. (4 to 8 inches thick)
Bt1--5 to 15 inches; brown (10YR 5/3) clay, brown (10YR 5/3) moist; weak medium prismatic structure that parts to strong medium and coarse subangular blocks; extremely hard, extremely firm, very sticky and very plastic; few medium, common fine and very fine roots; few medium interstitial, common very fine tubular pores; common thin clay films lining pores and on ped faces; 5 percent gravel; moderately acid (pH 6.0); clear wavy boundary. (4 to 15 inches thick)
Bt2--15 to 23 inches; light brownish gray (2.5Y 6/2) clay, olive (5Y 5/3) moist; moderate fine, medium and coarse subangular blocky structure; extremely hard, extremely firm, very sticky and very plastic; few medium and coarse, common fine and very fine roots; few coarse interstitial, common very fine tubular pores; common thin clay films lining pores and on ped faces; 5 percent gravel; cracks extend through horizon when dry, 1/2 inch wide, close above horizon; strongly acid (pH 5.5); gradual wavy boundary. (5 to 30 inches thick).
Bt3--23 to 43 inches; light brownish gray (2.5Y 6/2) clay, olive (5Y 5/3) moist; weak medium and coarse subangular blocky structure; extremely hard, extremely firm, very sticky and very plastic; common fine and very fine roots; few fine interstitial, few very fine interstitial, few very fine tubular pores; common thin clay films lining pores and ped faces; 10 percent gravel; cracks extend from about 41 inches upward into horizon above when dry, less than 1/2 inch thick; slightly acid (pH 6.5); gradual wavy boundary. (8 to 25 inches thick).
Bt4--43 to 63 inches; pale brown (10YR 6/3) gravelly clay loam, light olive brown (2.5Y 5/4) moist; weak fine and medium subangular blocky structure; extremely hard, extremely firm, very sticky and very plastic; few fine and very fine roots; few very fine tubular pores; few thin clay films lining pores and on ped faces; 15 percent gravel; slightly acid (pH 6.5).
TYPE LOCATION: Trinity County, California; 5.25 miles northeast of Hayfork; 0.1 mile west of Carr Creek Road on Highway 3, turn north onto dirt road, travel 0.2 miles north, pedon is 150 feet west of road; 1,500 feet west, 1,200 feet south of the northeast corner of section 35, T. 32 N., R. 11 W. Hayfork Summit Quadrangle.
RANGE IN CHARACTERISTICS: The particle-size control section averages 40 to 55 percent clay. Mean annual soil temperature is 52 to 59 degrees F. The soil moisture control section is dry in all parts early July to early October. The soil temperature at a depth of 20 inches exceeds 41 degrees F from about March 1 to January 1 (300 to 310 days), and exceeds 47 degrees F from about April 1 to December 1.
The A horizon is 10YR 5/3, 6/4, or 5/4. Moist color is10YR 4/3, 4/2, or 5/4. It is clay loam or loam. The A horizon is slightly acid or neutral.
The Bt horizon is 10YR 5/3, 6/3, 5/4, 5/6, 6/4, 6/6, 7.5YR 5/4, 5/6, or 2.5Y 6/2. Moist color is 10YR 5/3, 4/3, 4/4, 5/4, 2.5Y 5/4, or 5Y 5/3. The Bt horizon is clay, clay loam, gravelly clay, or gravelly clay loam. It contains 40 to 55 percent clay in the upper part and 30 to 40 percent clay in the lower part with 5 to 25 percent pebbles. The upper part of the Bt horizon has 15 to 20 percent more clay than the A horizon. It is neutral to strongly acid.
COMPETING SERIES: This is the Bostrum series. The Bostrum soil has a lithic contact at 20 to 40 inches.
GEOGRAPHIC SETTING: The Crefork soils are on hills. Elevation is 2,300 to 3,600 feet. Slopes are 2 to 50 percent. These soils formed in residuum from weakly consolidated mudstone and other fine-grained sedimentary deposits. The climate is characterized by warm, dry summers and cool, moist winters. Mean annual precipitation is 30 to 40 inches. Snowfall ranges from 0 to 12 inches. Mean January temperature is about 37 degrees F. Mean July temperature is about 71 degrees F. Mean annual temperature is 50 to 57 degrees F. The frost-free period is 90 to 130 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Haysum, Musserhill, and the Carrcreek soils. Haysum and Carrcreek soils have mollic epipedons greater than 20 inches thick. Carrcreek soils are in a loamy-skeletal family. Musserhill soils are in a loamy-skeletal family and are 20 to 40 inches deep over a paralithic contact.
DRAINAGE AND PERMEABILITY: Well drained; slow to rapid runoff; very slow permeability.
USE AND VEGETATION: This soil is used for wood products, grazing, and homesite development. Vegetation consists of Oregon white oak, California black oak, digger pine, buckbrush, fescue, and lemon needlegrass.
DISTRIBUTION AND EXTENT: The soils are not extensive. They occur in Hayfork and other intermountain valleys of the Klamath Mountains in northern California. MLRA is 5.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Trinity County, California; Weaverville area, 1990. Name is from Hayfork Creek.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon--the zone from the surface to a depth of 5 inches (A horizon).
Argillic horizon--the zone from 5 to 63 inches (Bt1, Bt2, Bt3, Bt4 horizons).
Particle-size control section--the zone from 5 inches to 25 inches (Bt1, Bt2, Bt3 horizons).
Abrupt textural change--clay content increases by 15 to 20 percent from the A to the Bt1.
ADDITIONAL REMARKS: Lincoln Lab data for samples 827177-827179.