LOCATION ISLANDBAR CAEstablished Series
TAXONOMIC CLASS: Coarse-loamy, mixed, active, mesic Typic Dystroxerepts
TYPICAL PEDON: Islandbar sandy loam, on a northwest facing 5 percent slope under a cover of conifers, hardwoods and shrubs at an elevation of 2220 feet, (677 m). When described on 7/22/1998 the soil was dry to a depth of 36 inches, (91 cm) and was slightly moist from 36 to 72 inches, (91 to 183 cm). (Colors are for dry soil unless otherwise noted).
Oi--0 to 2 inches, (0 to 5 cm); slightly decomposed plant material; abrupt smooth boundary.
A1--2 to 5 inches, (5 to 13 cm); light brownish gray (10YR 6/2) sandy loam, dark grayish brown (10YR 4/2) moist; 12 percent clay; weak fine subangular blocky parting to weak fine granular structure; slightly hard, very friable, nonsticky, nonplastic; many very fine and fine roots; many very fine and fine irregular pores; 5 percent mica flakes; 5 percent rounded gravel; moderately acid, pH 6.0 by Hellige-Truog; abrupt smooth boundary.
A2--5 to 9 inches, (13 to 23 cm); pale brown (10YR 6/3) sandy loam, dark grayish brown (10YR 4/2) moist; 10 percent clay; weak very fine subangular blocky parting to weak fine granular structure; slightly hard, very friable, nonsticky, nonplastic; common very fine and fine roots; common very fine tubular pores; 20 percent mica flakes; 5 percent subrounded gravel; moderately acid, pH 5.8 by Hellige-Truog; abrupt smooth boundary. (Combined thickness of the A horizon is 3 to 19 inches, (8 to 48 cm) thick).
Bw1--9 to 27 inches, (23 to 69 cm); light yellowish brown (10YR 6/4) sandy loam, brown (10YR 4/3) moist; 5 percent clay; weak very fine subangular blocky parting to weak fine granular structure; slightly hard, very friable, nonsticky, nonplastic; common fine and medium roots; common very fine tubular pores; 25 percent mica flakes; 5 percent subrounded gravel; moderately acid, pH 5.8 by Hellige-Truog; clear smooth boundary.
Bw2--27 to 36 inches, (69 to 91 cm); very pale brown (10YR 7/4) sandy loam, yellowish brown (10YR 5/4) moist; 7 percent clay; weak very fine subangular blocky structure; slightly hard, very friable, nonsticky, nonplastic; common fine and medium roots and few coarse roots; common very fine tubular pores; 30 percent mica flakes; 5 percent subrounded gravel; moderately acid, pH 5.8 by Hellige-Truog; clear smooth boundary.
Bw3--36 to 47 inches, (91 to 119 cm); pink (7.5YR 7/4) sandy loam, brown (7.5YR 5/4) moist; 12 percent clay; weak very fine subangular blocky structure; slightly hard, very friable, nonsticky, nonplastic; common fine and medium roots and few coarse roots; common very fine tubular pores; 35 percent mica flakes; 5 percent subrounded gravel; moderately acid, pH 5.8 by Hellige-Truog; clear smooth boundary.
Bw4--47 to 58 inches, (119 to 147 cm); pink (7.5YR 7/4) sandy loam, light brown (7.5YR 6/4) moist; 10 percent clay; weak very fine subangular blocky structure; slightly hard, very friable, nonsticky, nonplastic; common fine and medium roots; common very fine tubular pores; moderately acid, pH 5.8 by Hellige-Truog; gradual wavy boundary. (Combined thickness of the Bw horizon is 5 to 54 inches, (13 to 137 cm) thick).
C1--58 to 62 inches, (147 to 157 cm); very pale brown (10YR 8/4) loamy sand, yellowish brown (10YR 5/4) moist; 2 percent clay; massive; slightly hard, very friable, nonsticky, nonplastic; common fine roots; many very fine interstitial pores; moderately acid, pH 5.8 by Hellige-Truog; gradual wavy boundary. (0 to 74 inches, (0 to 188 cm) thick)
C2--62 to 72 inches, (157 to 183 cm); extremely gravelly loamy sand; 2 percent clay; massive; very hard, extremely firm, nonsticky, nonplastic; 90 percent subangular gravel; moderately acid, pH 6.0 by Hellige-Truog.
TYPE LOCATION: Butte County, California, about 2 miles west of Featherfalls, approximately 20 feet west and 1300 feet south of the northeast corner of Section 16, Township 20 N., Range 6 E., 39 degrees, 35 minutes, 47 seconds North latitude and 121 degrees, 17 minutes, 50 seconds West longitude, NAD83 - U.S.G.S. Quad: Forbestown, California.
RANGE IN CHARACTERISTICS: Depth to paralithic bedrock is greater than 60 inches, (152 cm). The mean annual soil temperature is 53 to 59 degrees F, (12 to 15 degrees C). The particle-size control section averages 5 to 18 percent clay and 0 to 30 percent rock fragments, mostly gravel. Mineralogy is mixed. Organic matter ranges from 1 to 2 percent to a depth of 9 inches, (23 cm). Rock fragments on the surface range from 5 to 10 percent gravel. Some pedons lack a C horizon.
The A horizon dry color is 10YR 5/2, 5/3, 6/2, 6/3, 6/4 or 7/2. Moist color is 10YR 3/1, 3/2, 4/2 or 4/3. Texture is sandy loam, fine sandy loam or gravelly sandy loam. Clay content ranges from 10 to 18 percent. Rock fragments range from 5 to 20 percent gravel. Reaction ranges from moderately acid to neutral.
The Bw horizon dry color is 10YR 6/3, 6/4, 7/2, 7/3, 7/4, 8/3, 8/4, 7.5YR 7/4, 2.5Y 7/8 or 8/3. Moist color is 10YR 4/2, 4/3, 4/4, 5/3, 5/4, 6/3, 6/4, 7/4, 7/6, 7.5YR 5/4, 5/6, 6/4, 6/6, 2.5Y 7/8 or 8/3. Texture is sandy loam, fine sandy loam, coarse sandy loam, gravelly sandy loam or gravelly fine sandy loam. Clay content ranges from 5 to 18 percent. Rock fragments range from 0 to 30 percent gravel. Reaction ranges from strongly acid to neutral.
The C horizon dry color is 10YR 6/3, 7/3, 7/4, 8/3, 8/4 or 2.5Y 8/3. Moist color is 10YR 4/3, 4/4, 5/4, 7/4, 7/6 or 2.5Y 6/3. Texture is loamy sand, gravelly sandy loam, gravelly loamy sand, loamy coarse sand, gravelly loamy coarse sand, very gravelly loamy coarse sand, extremely gravelly loamy sand or sandy loam. Clay content ranges from 2 to 18 percent. Rock fragments range from 0 to 90 percent gravel. Reaction ranges from strongly acid to neutral.
COMPETING SERIES: There are no other series in this family.
GEOGRAPHIC SETTING: Islandbar soils are on ridge tops and side slopes on granitic Sierra Nevada mountains. Slopes range from 2 to 70 percent. These soils formed in residuum and colluvium weathered from coarse grained intrusive rocks such as quartz diorite and trondhjemite. Elevation is 900 to 3175 feet, (274 to 968 m). The mean annual precipitation is 50 to 65 inches, (1270 to 1651 mm). The mean annual temperature is 54 to 57 degrees F, (12 to 14 degrees C). Frost free season is 170 to 235 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Craigsaddle, Crystalhill, Chawanakee, Featherfalls, Jocal, Oregongulch, Powellton, Sites and Toadtown soils. Craigsaddle soils are deep to densic bedrock, fine-loamy and thermic. Chawanakee soils are shallow and loamy. Featherfalls soils are fine-loamy. Jocal soils are very deep, fine-loamy, and have base saturation less than 35 percent. Powellton soils are very deep, fine-loamy, have parasesquic mineralogy and have base saturation less than 35 percent. Sites soils are very deep, fine and have base saturation less than 35 percent. Toadtown soils are very deep, fine, have parasesquic mineralogy and have base saturation less than 35 percent.
DRAINAGE AND PERMEABILITY: Somewhat excessively drained; low to medium runoff; moderately rapid saturated hydraulic conductivity in the A and Bw horizons and moderately rapid to very rapid in the C horizon.
USE AND VEGETATION: This soil is used for timber production, wildlife habitat, home site development and watershed. Vegetation is ponderosa pine, Douglas-fir, incense cedar, Pacific madrone, California black oak, tanoak, some canyon live oak and California laurel with a dense understory of whiteleaf manzanita, deerbrush, Pacific poison oak, honeysuckle, dogwood, toyon, Sierra iris, and scattered California torreya, foothill pine, bigleaf maple, California hazel, brackenfern, western thimbleberry and carex.
DISTRIBUTION AND EXTENT: Butte County, California and occur in (M261Ef) Granitic and Metamorphic Hills subsection of the (M261F) Sierra Nevada Mountains section. MLRA: 22A - Sierra Nevada Range. The soils are inextensive and occur on the Bald Rock and Concow plutons.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Butte County, California 2005. Source of name from Island Bar Hill on the Forbestown Quad.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - zone from 2 to 9 inches, (5 to 23 cm) (A1, A2)
Cambic horizon - zone from 9 to 58 inches, (23 to 147 cm) (Bw1, Bw2, Bw3, Bw4)
Particle-size control section for this pedon: 10 to 40 inches, (25 to 102 cm). The soil moisture control section - zone from 12 to 32 inches, (30 to 81 cm) is dry in all parts from about June to mid October (about 135 days).
Paralithic contact observed in roadcuts, below a depth of 203 cm.
Base saturation by ammonium acetate is assumed to be less than 60 percent.