LOCATION STONEHILL CA

Established Series
Rev: JHP/JPS/ET
01/2013

STONEHILL SERIES

The Stonehill series consists of moderately deep, well drained soils formed in colluvium and residuum from schist, capped with loess. Stonehill soils are on mountains and have slopes of 30 to 50 percent. The mean annual precipitation is about 1900 millimeters (75 inches) and the mean annual temperature is about 11 degrees C (52 degrees F).

TAXONOMIC CLASS: Fine-loamy, mixed, superactive, isomesic Typic Haplohumults

TYPICAL PEDON: Stonehill cobbly silt loam - on a convex northeast facing slope of 42 percent under Sitka spruce, red alder, redwood, and salmonberry at 213 meters (700 feet) elevation. (Colors are for moist soil unless otherwise stated. When described February 13, 1991, the soil was moist throughout.)

Oi--0 to 3 centimeters (0 to 1 inch); fresh and slightly decomposed red alder leaves, Sitka spruce needles, cones, and twigs; very strongly acid (pH 4.5).

Oa--3 to 13 centimeters (1 to 4 inches); mostly decomposed fine organic matter and humus; many very fine, common fine and few medium roots; abrupt wavy boundary; very strongly acid (pH 4.5). (Combined thickness of Oi and Oa is 5 to 15 centimeters)

A1--13 to 32 centimeters (4 to 13 inches); very dark brown (10YR 2/2) cobbly silt loam, dark brown (10YR 3/3) dry; weak fine granular structure; soft, very friable, slightly sticky and slightly plastic; many fine and fine, common medium and coarse roots; many very fine irregular, common very fine and fine and few medium tubular pores; 11 percent gravel and 10 percent cobbles; very strongly acid (pH 4.6); gradual smooth boundary.

A2--32 to 52 centimeters (13 to 20 inches); dark brown (7.5YR 3/2) cobbly silt loam, brown (10YR 4/3) dry; weak fine and medium subangular blocky structure; soft, friable, slightly sticky and slightly plastic; many very fine, common fine, medium and coarse roots; common very fine irregular and common very fine, fine and medium tubular pores; 17 percent gravel and 15 percent cobbles; very strongly acid (pH 4.8); clear wavy boundary. (Combined thickness of A1 and A2 horizons is 20 to 48 centimeters)

BAt--52 to 64 centimeters (20 to 25 inches); dark brown (7.5YR 3/4) cobbly silty clay loam, yellowish brown (10YR 5/4) dry; weak medium and coarse subangular blocky structure; soft, friable, slightly sticky and slightly plastic; common very fine and fine, few medium and coarse roots; common very fine and fine and few medium tubular pores; 11 percent gravel and 10 percent cobbles; very strongly acid (pH 5.0); clear irregular boundary. (12 to 40 centimeters thick)

Bt--64 to 82 centimeters (25 to 32 inches); dark yellowish brown (10YR 4/4) gravelly silty clay loam, light yellowish brown (10YR 6/4) dry; weak medium and coarse subangular blocky structure; slightly hard, friable, moderately sticky and slightly plastic; common very fine, fine and medium, few coarse roots; common very fine and few fine tubular pores; few faint clay films on ped faces and coating gravel in lower part; 25 percent gravel; very strongly acid (pH 4.9); clear wavy boundary. (12 to 50 centimeters thick)

R--82 centimeters (32 inches); weathered schist, fragments removable with knife or spade, becoming harder with depth; fingers of soil in joints in upper part; joint spacing is 5 to 10 centimeters; few very fine and fine roots in joints. (depth to upper boundary ranges from 73 to 97 centimeters within pit)

TYPE LOCATION: Redwood National Park, Humboldt County, California; located approximately 4 kilometers south of the town of Orick, on Stone Hill, 305 meters south of gate to West Side Access Road; northeast quarter, southwest quarter, Section 8, T. 10 N., R. 1 E.; 41 degrees, 16 minutes, 17 seconds north latitude and 124 degrees, 4 minutes, 52 seconds west longitude; HBLM; USGS Orick Quadrangle. UTM Zone 10 409443mE 4569446mN; NAD83.

RANGE IN CHARACTERISTICS:

Soil moisture: The soil is continuously moist in all parts in the soil moisture control section in most years. The soils have an udic moisture regime.

Soil temperature: The mean annual soil temperature is 10 to 13 degrees C (50 to 55 degrees F). The difference between mean summer and mean winter temperature is 2 to 4 degrees C.

Depth to a lithic contact: 50 to 100 centimeters.

Organic matter: There is 15 to 20 Kg organic carbon per square meter to the lithic contact.

The umbric epipedon is 25 to 50 centimeters thick.

Reaction is very strongly acid throughout, and base saturation is less than 35 percent above the lithic contact.

Particle-Size Control Section (weighted average):
Rock fragments: 15 to 30 percent gravel and 0 to 10 percent cobbles.
Clay content: 25 to 35 percent clay.

O horizon

Hue: 10YR.
Value: 2 through 6 dry and moist.
Chroma: 1 through 4 dry and moist.

Texture: slightly to mostly decomposed organic material.
Wood fragments: 0 to 35 percent.
Reaction: moderately to very strongly acid.

A horizon

Hue: 7.5YR or 10YR.
Value: 3 or 4 dry, 2 or 3 moist.
Chroma: 3 or 4 dry, 2 or 3 moist.

Texture of fine earth: silt loam.
Rock fragments: 5 to 20 percent gravel and 0 to 15 percent cobbles.
Clay content: 12 to 20 percent clay.

Bt horizon

Hue: 7.5YR or 10YR.
Value: 5 or 6 dry, 3 or 4 moist.
Chroma: 4 dry, 4 moist.

Texture of fine earth: silt loam, clay loam or silty clay loam.
Rock fragments: 15 to 30 percent gravel and 0 to 10 percent cobbles.
Pararock Fragments: 0 to 20 percent paragravel.
Clay content: 25 to 35 percent clay.

COMPETING SERIES: These are the Espa, Ladybird and Ossagon series. Espa lacks rock fragments within the profile. Ladybird soils have angular rock fragments throughout. In addition, Espa, Ladybird and Ossagon soils are greater than 150 centimeters deep to a lithic contact.

GEOGRAPHIC SETTING: Stonehill soils are on ridges and convex mountain slopes above the Pacific Ocean. Slopes are 30 to 50 percent. Elevations are 5 to 541 meters (15 to 1770 feet). The soils formed in material weathered from schist, capped with loess. The climate is humid with cool, foggy summers and cool, rainy winters. Mean annual precipitation is 1780 to 2160 millimeters (70 to 85 inches). Mean January temperature is about 9 degrees C; mean July temperature is about 14 degrees C; and the mean annual temperature is 10 to 13 degrees C (50 to 55 degrees F). Frost-free season is about 250 to 300 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Ladybird soils. Ladybird soils are greater than 150 centimeters to a lithic contact. The Ladybird soils are on straight to gently concave mountain slopes below the Stonehill soils.

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Well drained; high runoff; moderately high saturated hydraulic conductivity.

USE AND VEGETATION: This soil has been used for commercial timber, wildlife, and watershed. Natural vegetation consists of Sitka spruce, red alder, redwood, salmonberry, salal, and swordfern.

DISTRIBUTION AND EXTENT: California Coastal Redwood Belt; MLRA 4B. The series is not extensive.

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

SERIES ESTABLISHED: Humboldt and Del Norte area, California, 2007. The source of the name is from Stone Hill, located in Redwood National Park south of the town of Orick.

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

1. Umbric epipedon - the zone from 13 to 52 centimeters (A1& A2 horizons)
2. Argillic horizon - the zone from 52 to 82 centimeters (BAt & Bt
horizons)
3. Lithic contact - the bedrock interface at 82 centimeters depth
4. Ultisol feature - base saturation is 3 percent above the lithic contact
5. Humult feature - 2.98 percent or more organic carbon in upper 15 centimeters of argillic
6. Particle-size control section - the zone from 52 to 82 centimeters, averages 30 percent clay, by field estimate, and 23 percent rock fragments, by volume. CEC/clay ratio averages 0.71

ADDITIONAL DATA: Soil profile sample 91-RNP-1 was collected at the type location and analyzed at the Oregon State University soil-testing laboratory.

Soil classified using the 10th Edition of the Keys to Soil Taxonomy.

National Cooperative Soil Survey
U.S.A.