LOCATION SUPPLYCREEK CA

Established Series
REV: BAL/JPS/ET
10/2016

SUPPLYCREEK SERIES

The Supplycreek series consists of very deep (moderately deep to highly fractured bedrock), well drained soils formed in colluvium and residuum derived from serpentinite rock. These soils are on mountains and have slopes of 9 to 75 percent. Mean annual precipitation is 1524 millimeters (60 inches) and the mean annual temperature is 12 degrees C (54 degrees F).

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

TYPICAL PEDON: Supplycreek very gravelly loam - under tanoak, ponderosa pine and sugar pine with an understory of manzanita, bear grass, and fescue at an elevation of 1080 meters. When described on July 29, 2002 the soil was dry throughout. (Colors are for dry soil unless otherwise stated).

Oi--0 to 2 centimeters (0 to 1 inches); recent and partially decomposed needles and leaves of sugar pine, tanoak, and manzanita; moderately acid (pH 5.6); abrupt smooth boundary. (0 to 10 centimeters thick)

A1--2 to 12 centimeters (1 to 5 inches); yellowish brown (10YR 5/4), very gravelly loam, dark brown (7.5YR 3/3), moist; moderate fine subangular blocky structure parting to strong very fine granular; soft, very friable, slightly sticky and slightly plastic; many very fine, fine, and common medium roots; many very fine, common fine and medium tubular pores; 45 percent gravel, 5 percent cobbles; slightly acid (pH 6.1); abrupt smooth boundary.

A2--12 to 28 centimeters (5 to 11 inches); yellowish brown (10YR 5/4), very gravelly loam, dark brown (7.5YR 3/4), moist; moderate fine subangular blocky structure parting to strong very fine granular; soft, very friable, slightly sticky and slightly plastic; many very fine, medium, and few fine roots; common very fine, fine, and medium tubular pores; 35 percent gravel, 10 percent cobbles; slightly acid (pH 6.4); clear smooth boundary. (Combined thickness of the A horizons is 10 to 38 centimeters)

Bt1--28 to 43 centimeters (11 to 17 inches); brown (7.5YR 5/4), very gravelly loam, dark brown (7.5YR 3/4), moist; moderate fine subangular blocky structure; hard, friable, slightly sticky and moderately plastic; many fine, medium, and few coarse roots; many fine and common medium tubular pores; few distinct clay films on all faces of peds; 40 percent gravel, 15 percent cobbles; neutral (pH6.8); clear smooth boundary.

Bt2--43 to 64 centimeters (17 to 25 inches); strong brown (7.5YR 5/6), extremely gravelly clay loam, dark brown (7.5YR 3/4), moist; moderate fine subangular blocky structure; hard, friable, slightly sticky and moderately plastic; many fine, medium, and few coarse roots; many fine and medium tubular pores; few faint clay films on all faces of peds; 50 percent gravel, 10 percent cobbles; neutral (pH 6.8); abrupt wavy boundary.

Bt3--64 to 84 centimeters (25 to 33 inches); brown (7.5YR 5/4), extremely gravelly sandy clay loam, dark brown (7.5YR 3/4), moist; moderate fine subangular blocky structure; soft, friable, slightly sticky and moderately plastic; many fine, medium, and few coarse roots; many fine, medium, and common coarse tubular pores; very few faint clay films on all faces of peds; 60 percent gravel, 15 percent cobbles; neutral (pH 6.8); abrupt irregular boundary. (Combined thickness of Bt horizons is 40 to 80 centimeters)

2BCt--84 to 99 centimeters (33 to 39 inches); brown (7.5YR 5/4), extremely gravelly sandy clay loam, dark brown (7.5YR 3/4), moist; massive; soft, friable, moderately sticky and moderately plastic; common coarse roots; many medium irregular pores; many faint clay films on all faces of peds; 65 percent gravel, 10 percent cobbles; neutral (pH 6.8).

2C--99 to 180 centimeters (39 to 71) extremely fractured serpentine with cracks 1 to 10 centimeters apart and containing no soil; gravel; few fine and medium roots.

TYPE LOCATION: Humboldt County, California; Hoopa Tribal Nation, about 3 kilometers west of the town of Hoopa near Supply Creek; section 5, township 7 north, 4 east; WGS84 Decimal degrees 41.1358333 latitude, and -123.7677778 longitude; UTM 435559 meters E, 4542129 meters N, zone 10, NAD83.

RANGE IN CHARACTERISTICS:

Soil moisture: The soil moisture control section is dry from July 1st to October 15th and moist in all parts from November 15 to June 1st. The soil has a xeric soil moisture regime.
Soil temperature: The mean annual soil temperature is 10 to 15 degrees C (50 to 59 degrees F). The difference between the mean summer and mean winter temperature is greater than 6 degrees C. The soil has a mesic soil temperature regime.
Soil Depth: Depth to highly fractured serpentine is 60 to 100 centimeters (24 to 39 inches). The fractures that roots can enter are less than 10 centimeters apart.
Base saturation: by the ammonium acetate method is greater than 35 percent throughout.
Soil reaction: slightly acid to neutral throughout the soil profile.
Surface fragments: 5 to 10 percent gravel, 0 to 15 cobbles, or 0 to 10 percent stones
Particle Size Control Section (weighted average):
Clay: ranges: 20 to 35 percent.
Rock fragments: 35 to 60 percent gravel and 0 to 15 percent cobbles

A Horizon

Hue: 10YR or 7.5YR

Value: 4 or 5 dry, 2 or 3 moist.
Chroma: 2 through 4 dry or moist.

Texture of fine earth fraction: loam or sandy loam
Clay content: 15 to 20 percent.
Rock fragments: 35 to 45 percent gravel and 0 to 10 percent cobbles

Bt Horizons

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

Texture of fine earth fraction: loam, clay loam or sandy clay loam
Clay content: 20 to 35 percent.
Rock fragments: 35 to 60 percent gravel and 0 to 15 percent cobbles

2BCt Horizons

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

Texture of fine earth fraction: sandy clay loam
Clay content: 25 to 35 percent.
Rock fragments: 60 to 70 percent gravel and 0 to 15 percent cobbles

2C Horizon

In lieu of texture: gravel
Rock fragments: 90 to 100 percent gravel and cobbles

COMPETING SERIES: This is the Sugapine series. The Sugapine soil does not have fractured serpentinite bedrock within 100 centimeters.

GEOGRAPHIC SETTING: These soils occur on mountains with slopes of 9 to 75 percent at elevations of 34 to 1265 meters (112 to 4150 feet) on linear and concave side slopes. These soils formed in colluvium and residuum from ultramafic serpentinite. The climate is subhumid with warm dry summers and cool moist winters. The mean annual precipitation is 1250 to 2032 millimeters (49 to 80 inches). Mean annual air temperature is about 12 degrees C (54 degrees F). Mean summer temperature is 20 degrees C and the mean winter temperature is 7 degrees C, and the mean annual temperature is 9 to 13 degrees C (49 to 57 degrees F). The growing season is about 90 to 150 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Bramlet and Sugapine soils. Bramlet soils are shallow to a lithic contact and are on convex ridge summits. Sugapine soils are very deep, do not have fractured bedrock within 100 centimeters of the soil surface and are on linear to concave slopes adjacent to the Supplycreek soils.

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

USE AND VEGETATION: Used for wildlife habitat, and watershed protection. Native vegetation is sugar pine, Jeffery pine, knobcone pine, incense cedar, Douglas-fir, hairy Manzanita, huckleberry oak, California wildrose and bear grass.

DISTRIBUTION AND EXTENT: Siskiyou-Trinity Area, MLRA 5. These soils are of small extent.

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

SERIES ESTABLISHED: Humboldt and Del Norte Area, California, 2012. Proposed 2003.

REMARKS: Diagnostic horizons and features include:

1. Ochric Epipedon - The zone from 0 to 28 centimeters (Oi, A1, and A2 horizons)
2. Argillic horizon - The zone from 28 to 99 centimeters (Bt1, Bt2, Bt3 and BCt horizons)
3. Particle-size control section - the zone from 28 to 78 centimeters, averages 31 percent clay, by weight, and 62 percent rock fragments, by volume. (Bt1, Bt2, Bt3 horizons)
4. Mollic intergrade - the zone from 2 to 12 centimeters has .7 percent or more organic carbon throughout (A1 horizon)

Soil classified using the 12th Edition of the Keys to Soil Taxonomy.

NASIS User Pedon ID: 02CA023605035

National Cooperative Soil Survey
U.S.A.