LOCATION OREGONGULCH CAEstablished Series
TAXONOMIC CLASS: Coarse-loamy, mixed, active, thermic Typic Haploxerepts
TYPICAL PEDON: Oregongulch gravelly sandy loam, on a southeast facing 28 percent slope under a cover of whiteleaf manzanita, live oak, Pacific madrone, toyon, Pacific poison oak, foothill pine and scattered ponderosa pine at an elevation of 1000 feet, (305 m). When described on 9/29/1998 the soil was dry throughout. (Colors are for dry soil unless otherwise noted).
Oi--0 to 1 inches, (0 to 3 cm); slightly decomposed plant material; abrupt smooth boundary.
A--1 to 4 inches, (3 to 10 cm); light gray (10YR 7/2) gravelly sandy loam, dark grayish brown (10YR 4/2) moist; 10 percent clay; weak very fine subangular blocky structure; slightly hard, friable, nonsticky, nonplastic; few very fine roots; many very fine interstitial pores; 30 percent subangular gravel; slightly acid, pH 6.5 by Hellige-Truog; clear smooth boundary. (3 to 8 inches, (8 to 20 cm) thick)
Bw1--4 to 7 inches, (10 to 18 cm); very pale brown (10YR 7/3) gravelly sandy loam, brown (10YR 5/3) moist; 12 percent clay; weak fine subangular blocky structure; slightly hard, friable, nonsticky, nonplastic; few very fine to medium roots; many very fine interstitial pores; 20 percent subangular gravel; strongly acid, pH 5.5 by Hellige-Truog; clear smooth boundary.
Bw2--7 to 13 inches, (18 to 33 cm); very pale brown (10YR 7/3) gravelly sandy loam, yellowish brown (10YR 5/4) moist; 15 percent clay; moderate fine subangular blocky structure; slightly hard, firm, nonsticky, nonplastic; common medium and coarse roots; common very fine interstitial pores; 25 percent subangular gravel; moderately acid, pH 6.0 by Hellige-Truog; clear smooth boundary.
Bw3--13 to 18 inches, (33 to 46 cm); very pale brown (10YR 7/3) gravelly sandy loam, yellowish brown (10YR 5/4) moist; 15 percent clay; moderate fine subangular blocky structure; slightly hard, firm, nonsticky, nonplastic; common medium roots; common very fine interstitial pores; 30 percent subangular gravel; moderately acid, pH 5.8 by Hellige-Truog; abrupt smooth boundary. (Combined thickness of the Bw horizon is 14 to 16 inches, (36 to 41 cm) thick).
C--18 to 24 inches, (46 to 61 cm); very pale brown (10YR 7/3) very gravelly sandy loam, yellowish brown (10YR 5/4) moist; 13 percent clay; moderate medium subangular blocky structure; slightly hard, firm, nonsticky, nonplastic; common medium roots; common very fine interstitial pores; 40 percent subangular gravel; moderately acid, pH 5.8 by Hellige-Truog; abrupt smooth boundary. (0 to 26 inches, (0 to 66 cm) thick)
Cdt--24 to 60 inches, (61 to 152 cm); weathered densic trondhjemite bedrock very pale brown (10YR 8/3) very gravelly loamy coarse sand, very pale brown (10YR 7/3) moist; 5 percent clay; massive, hard, firm, noncemented, nonsticky, nonplastic; common medium and coarse roots in cracks; 20 percent discontinuous prominent yellowish red (5YR 5/6), moist, clay films on rocks; when crushed has 50 percent hard subangular gravel; moderately acid, pH 5.8 by Hellige-Truog.
TYPE LOCATION: Butte County, California, about 3.7 miles northwest of Forbestown, approximately 1900 feet west and 750 feet south of the northeast corner of Section 6, Township 19 N., Range 6 E., 39 degrees, 32 minutes, 22 seconds North latitude and 121 degrees, 20 minutes, 21 seconds West longitude, NAD83 - U.S.G.S. Quad: Forbestown, California.
RANGE IN CHARACTERISTICS: Depth to densic bedrock is 20 to 40 inches, (51 to 102 cm). The mean annual soil temperature is 59 to 64 degrees F, (15 to 18 degrees C). The particle-size control section averages 12 to 18 percent clay and 20 to 35 percent rock fragments, mostly gravel. Mineralogy is mixed. Organic matter ranges from 1 to 2.5 percent to a depth of 4 inches, (10 cm) and is less than 1 percent to a depth of 24 inches, (61 cm). Rock fragments on the surface range from 5 to 40 percent gravel.
The A horizon dry color is 10YR 5/2, 6/2 or 7/2. Moist color is 10YR 3/2, 4/2 or 4/3. Texture is gravelly sandy loam, gravelly coarse sandy loam, sandy loam or coarse sandy loam. Clay content ranges from 5 to 12 percent. Rock fragments range from 0 to 30 percent gravel. Reaction ranges from slightly acid to neutral.
The Bw horizon dry color is 10YR 6/2, 7/2, 7/3, 8/2 or 8/3. Moist color is 10YR 3/3, 4/3, 5/3, 5/4, 6/4 or 7/3. Texture is gravelly sandy loam, gravelly coarse sandy loam, coarse sandy loam or loamy coarse sand. Clay content ranges from 3 to 15 percent. Rock fragments range from 10 to 30 percent gravel. Reaction ranges from strongly acid to slightly acid.
The C horizon dry color is 10YR 7/3, 8/2 or 8/3. Moist color is 10YR 5/4 or 6/2. Texture is very gravelly sandy loam or gravelly loamy coarse sand. Clay content ranges from 3 to 13 percent. Rock fragments range from 20 to 50 percent gravel. Reaction ranges from moderately acid to slightly acid.
The Cdt horizon dry color is variegated 10YR 6/3, 7/3, 8/2, 8/3, 7.5YR 6/6, or 5YR 6/6. Moist color is variegated 10YR 5/4, 6/2, 6/4, 7/3, 7.5YR 5/6 or 5YR 4/6. When crushed, texture is gravelly sandy clay loam, loamy coarse sand, gravelly loamy coarse sand, very gravelly loamy coarse sand, very gravelly coarse sand or gravelly coarse sand. Clay content ranges from 1 to 22 percent. Rock fragments range from 10 to 50 percent gravel. Reaction ranges from strongly acid to slightly acid.
COMPETING SERIES: This is the Crystalhill series. Crystalhill soils are very deep to densic bedrock.
GEOGRAPHIC SETTING: Oregongulch soils are on ridge tops and side slopes on granitic Sierra Nevada foothills. Slopes range from 2 to 70 percent. These soils formed in residuum and colluvium weathered from trondhjemite. Elevation is 900 to 2000 feet, (274 to 610 m) and ranges to 2600 feet (792 m) on southwest aspects. Mean annual precipitation is 40 to 55 inches, (1016 to 1397 mm). The mean annual temperature is 56 to 60 degrees F, (13 to 16 degrees C). Frost free season is 230 to 260 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Craigsaddle, Crystalhill, Dunstone and Loafercreek soils. Craigsaddle soils are deep to densic bedrock and are fine-loamy. Crystalhill soils are very deep to densic bedrock. Dunstone soils are shallow to paralithic bedrock of greenschist and are loamy. Loafercreek soils are moderately deep to paralithic bedrock of greenschist and are fine-loamy.
DRAINAGE AND PERMEABILITY: Somewhat excessively drained; medium to high runoff; moderately rapid to very rapid saturated hydraulic conductivity in the A, Bw and C horizons.
USE AND VEGETATION: This soil is used for home site development, recreation and watershed. Vegetation is annual grasses, whiteleaf manzanita, toyon, Pacific poison oak, brackenfern, interior live oak, canyon live oak, Pacific madrone, foothill pine, incense cedar, California buckthorn, California honeysuckle and scattered ponderosa pine and California black oak.
DISTRIBUTION AND EXTENT: Butte County, California and occur in the (M261Fb) Lower Foothills Metamorphic Belt subsection of the (M261F) Sierra Nevada Foothills section. MLRA: 18 -- Sierra Nevada Foothills. The soils are inextensive and occur on the Bald Rock pluton.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Butte County, California 2005. Source of name from Oregon Gulch on the Forbestown quad.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - zone from 1 to 4 inches, (3 to 10 cm). (A)
Cambic horizon - zone from 4 to 24 inches, (10 to 61 cm). (Bw1, Bw2, Bw3, C)
Densic contact - zone from 24 to 60 inches, (61 to 152 cm) (Cdt)
Particle-size control section for this pedon: 10 to 24 inches, (25 to 61 cm)
The soil moisture control section - zone from 12 to 24 inches, (30 to 61 cm)
ADDITIONAL DATA: Used data from 72-CA-04-026X, University of California, Davis. Site located approximately 0.7 miles northwest.