LOCATION ORAGRAN                 CA

Established Series
REV: AMP/SRM/JPS/ET
02/2023

ORAGRAN SERIES

The Oragran series consists of shallow, well drained soils formed in material weathered from peridotite or serpentinite. Oragran soils are on mountains and have slopes of 5 to 75 percent. The mean annual precipitation is 2870 milimeters (113 inches) and the mean annual temperature is 10 degrees C (50 degrees F).

TAXONOMIC CLASS: Loamy, magnesic, mesic Lithic Haploxerepts

TYPICAL PEDON: Oragran very stony loam - on an east facing slope of 10 percent under knobcone pine, lodgepole pine, azalea, huckleberry oak and red huckleberry at 1332 meters (4060 feet) elevation. (Colors are for dry soil unless otherwise stated. When described on 10/11/79 the soil was moist throughout).

Oi--0 to 2 centimeters (0 to 1 inches); fresh and decomposing leaf and needle litter; moderately acid (pH 6.0).

A--2 to 8 centimeters (1 to 3 inches); yellowish brown (10YR 5/4) very stony loam, brown (10YR 4/3) moist; moderate very fine granular structure; soft, very friable, nonsticky and nonplastic; few very fine, common fine, and few medium roots throughout; many very fine interstitial and tubular pores; 15 percent gravel and 30 percent stones; moderately acid (pH 5.8); clear smooth boundary. (5 to 30 centimeters)

Bw--8 to 33 centimeters (3 to 13 inches); brownish yellow (10YR 6/8) stony silt loam, yellowish brown (10YR 5/6) moist, weak very fine subangular blocky structure; slightly hard, firm, slightly sticky and slightly plastic; few very fine, fine, medium and coarse roots throughout; many very fine interstitial and tubular pores; 15 percent stones; moderately acid (pH 6.0); abrupt irregular boundary. (13 to 30 centimeters thick)

R--33 centimeters (13 inches); fractured serpentinized peridotite; fractures 20 to 51 centimeters apart.

TYPE LOCATION: Del Norte County, California; a roadcut on the road to Red Mountain Lookout, about 1 mile northwest of the junction with south Red Mountain road; SW1/4, NW1/4, sec. 13, T.13N, R.2E, HBLM. USGS Klamath Glen Quadrangle. WGS84 Decimal degrees estimated from PLSS location: Std. Lat. 41.515, Std. Long. -123.897

RANGE IN CHARACTERISTICS:

Soil moisture: The soil between the depths of 10 (4 inches) and 33 centimeters (13 inches) is usually dry in all parts from June 15 to October 15 and moist in all parts from November 15 to April 15. The soils have a xeric moisture regime.

Soil temperature: The mean annual soil temperature is 10 to 15 degrees C (50 to 59 degrees F). The difference between mean summer and mean winter temperature is 6 to 10 degrees C. The soil has a mesic soil temperature regime.

Base saturation: is assumed to be greater than 60 percent in some part of the profile.

Depth to lithic contact: is 25 to 50 centimeters (10 to 20 inches).

Surface stones and cobbles range from 5 to 30 percent.

The particle-size control section:
Rock fragments: 10 to 35 percent
Clay content: 23 to 35 percent


O horizon

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

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

A horizon

Hue: 7.5YR or 10YR.
Value: 5 through 7 dry, 4 or 5 moist.
Chroma: 3 through 6 dry and moist.

Texture of fine earth: loam or silt loam.
Rock fragments: 10 to 20 percent gravel and 25 to 30 percent stones.
Clay content: 20 to 27 percent.
Reaction: neutral to moderately acid.

Bw horizon

Hue: 7.5YR, 10YR, or 2.5Y.
Value: 5 through 7 dry, 4 through 6 moist.
Chroma: 3 through 8 dry, 4 through 8 moist.

Texture of fine earth: loam, silt loam, or clay loam.
Rock fragments: 0 to 25 percent gravel and 15 to 20 percent stones.
Clay content: 15 to 35 percent.
Reaction: neutral to moderately acid.

COMPETING SERIES: At this time there are no other series in this family.

GEOGRAPHIC SETTING: Oragran soils are on mountain slopes and ridges. Slopes are 5 to 75 percent. Elevations are 55 to 1575 meters (180 to 3500 feet). The soils formed in material weathered from serpentine or serpentinized peridotite. The climate is humid with warm, dry summers and cool, wet winters. Mean annual precipitation is 2286 to 3050 millimeters (90 to 120 inches). Mean January temperature is 3 degrees C (37 degrees F.), and mean July temperature is 17 degrees C (63 degrees F.). Mean annual temperature is 9 to 15 degrees C (50 to 59 degrees F). Frost-free season is estimated to be about 100 to 180 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Gasquet, Jayel, Walnett, and Weitchepec soils. The Gasquet soils are 100 to 150 centimeters to a lithic contact. The Jayel and Weitchepec soils are 50 to 100 centimeters (20 to 40 inches) to a lithic contact. Walnett soils are greater than 152 centimeters (>60 inches) to a lithic contact. Gasquet soils are in concave to linear positions and are on more stable positions on mountain slopes. Jayel and Weitchepec soils are on convex to strongly convex positions. Walnett soils are on concave to linear positions on mountain slopes.

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

USE AND VEGETATION: These soils are used for recreation, watershed and wildlife habitat. Native vegetation is knobcone pine, huckleberry oak, azalea, California red huckleberry, California coffeeberry, with some lodgepole pine, sugar pine, Jeffrey pine, and incense-cedar.

DISTRIBUTION AND EXTENT: Northwestern California. The series is moderately extensive.

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

SERIES ESTABLISHED: Del Norte County, California, 1981. Source of name from a mine near Big Flat Guard Station about 8 miles south of Gasquet.

REMARKS: This series was established to identify and map a new family in a survey area that classified soil map unit components only to the family level. Mineralogy is assumed based on data by the Lincoln lab on similar soils weathered from serpentinized or serpentinitic bedrock. Updated to series level for Soil Survey of Humboldt and Del Norte Counties, December 2007.

ADDITIONAL DATA:

User Pedon ID: 79023001

Source: 11th Edition of the Keys to Soil Taxonomy.

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National Cooperative Soil Survey
U.S.A.