LOCATION THERMALITO CAEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, active, thermic Abruptic Durixeralfs
TYPICAL PEDON: Thermalito sandy loam, on a 3 percent slope under a cover of annual grasses and forbs at an elevation of 161 feet, (49 m). When described on 4/17/1997 the soil was slightly moist throughout. (Colors are for dry soil unless otherwise noted).
A--0 to 2 inches, (0 to 5 cm); brown (7.5YR 5/4) sandy loam, dark reddish brown (5YR 3/4) moist; 15 percent clay; moderate fine platy parting to moderate fine subangular blocky structure; slightly hard, very friable, nonsticky, nonplastic; common very fine roots; few very fine tubular pores; 5 percent fine irregular strong brown (7.5YR 4/6) oxidized iron masses; 10 percent well rounded gravel; slightly acid, pH 6.5 by Hellige-Truog; abrupt smooth boundary. (1 to 6 inches, (3 to 15 cm) thick)
Bt1--2 to 6 inches, (5 to 15 cm); light brown (7.5YR 6/4) gravelly sandy loam, reddish brown (5YR 4/4) moist; 20 percent clay; moderate medium subangular blocky structure; hard, friable, nonsticky, nonplastic; common very fine roots; few very fine tubular pores; 20 percent discontinuous distinct clay films on faces of peds; 2 percent fine irregular black (N 2/0), manganese masses and 5 percent fine irregular strong brown (7.5YR 4/6) oxidized iron masses; 20 percent well gravel; strongly acid, pH 5.5 by Hellige-Truog; abrupt smooth boundary.
Bt2--6 to 12 inches, (15 to 30 cm); light brown (7.5YR 6/4) sandy clay loam, reddish brown (5YR 4/4) moist; 24 percent clay; moderate medium subangular blocky structure; slightly hard, friable, slightly sticky, slightly plastic; common very fine roots; few fine tubular and common very fine tubular pores; 30 percent discontinuous distinct clay films on faces of peds; 10 percent well rounded gravel; strongly acid, pH 5.5 by Hellige-Truog; abrupt smooth boundary.
Bt3--12 to 18 inches, (30 to 46 cm); reddish yellow (7.5YR 6/6) gravelly sandy clay loam, reddish brown (5YR 4/4) moist; 28 percent clay; moderate medium subangular blocky structure; hard, friable, slightly sticky, slightly plastic; few very fine roots; few fine tubular and common very fine tubular pores; 50 percent discontinuous distinct clay films on faces of peds; 25 percent well rounded gravel; strongly acid, pH 5.5 by Hellige-Truog; abrupt smooth boundary.
Bt4--18 to 23 inches, (46 to 58 cm); light brown (7.5YR 6/4) gravelly sandy clay loam, reddish brown (5YR 5/4) moist; 30 percent clay; moderate fine subangular blocky structure; hard, firm, slightly sticky, slightly plastic; few very fine roots; few fine tubular and common very fine tubular pores; 50 percent discontinuous distinct clay films on faces of peds; 25 percent well rounded gravel; strongly acid, pH 5.5 by Hellige-Truog; abrupt smooth boundary.
Bt5--23 to 25 inches, (58 to 63 cm); reddish yellow (5YR 6/6) gravelly sandy clay loam, yellowish red (5YR 4/6) moist; 33 percent clay; moderate fine subangular blocky structure; hard, firm, moderately sticky, moderately plastic; few very fine roots; few fine tubular pores; 50 percent discontinuous distinct clay films on faces of peds; 20 percent well rounded gravel; moderately acid, pH 6.0 by Hellige-Truog; abrupt smooth boundary. (Combined thickness of the Bt horizon is 12 to 23 inches, (30 to 58 cm) thick).
2Bt6--25 to 29 inches, (63 to 74 cm); red (2.5YR 5/6) gravelly clay, red (2.5YR 4/6) moist; 50 percent clay; moderate fine angular blocky structure; extremely hard, very firm, very sticky, moderately plastic; few very fine roots; few very fine tubular pores; 55 percent discontinuous distinct clay films on faces of peds; 25 percent well rounded gravel; moderately acid, pH 6.0 by Hellige-Truog; abrupt smooth boundary.
2Bt7--29 to 32 inches, (74 to 81 cm); yellowish red (5YR 5/6) gravelly clay, red (2.5YR 4/6) moist; 45 percent clay; moderate fine angular blocky structure; extremely hard, very firm, very sticky, moderately plastic; few very fine roots; few very fine tubular pores; 55 percent discontinuous distinct clay films on faces of peds; 2 percent fine irregular black (N 2/0), manganese masses; 30 percent well rounded gravel; moderately acid, pH 6.0 by Hellige-Truog; abrupt smooth boundary. (Combined thickness of the 2Bt horizon is 6 to 16 inches, (15 to 41 cm) thick).
3Bqm--32 to 60 inches, (81 to 152 cm); indurated duripan, cemented by silica; 30 percent well rounded gravel.
TYPE LOCATION: Butte County, California, about 3.8 miles west of Oroville, approximately 1600 west and 650 feet south of the northeast corner of Section 16, Township 19 N., Range 3 E., 39 degrees, 30 minutes, 28 seconds North latitude and 121 degrees, 38 minutes, 15 seconds West longitude, NAD83 - U.S.G.S. Quad: Shippee, California.
RANGE IN CHARACTERISTICS: Depth to indurated gravelly duripan is 20 to 40 inches, (51 to 102 cm) and depth to 2Bt horizon ranges from 18 to 25 inches, (46 to 63 cm). The mean annual soil temperature is 61 to 64 degrees F, (16 to 18 degrees C). The particle-size control section averages 24 to 35 percent clay and 2 to 30 percent rock fragments, mostly gravel. Mineralogy is mixed. A fluctuating water table can occur from the top of the duripan to 14 inches, (36 cm) below the surface of the soil from December through April. Rock fragments on the surface range from 0 to 20 percent gravel.
The A horizon dry color is 7.5YR 5/4, 5/6, 6/4, 6/6, 7/3, 10YR 6/4 or 7/3. Moist color is 5YR 3/4, 4/4, 4/6, 7.5YR 3/3, 4/3, 5/4 or 10YR 3/4. Texture is sandy loam, gravelly sandy loam, fine sandy loam or loam. Clay content ranges from 12 to 20 percent. Organic matter ranges from 0.5 to 2 percent. Rock fragments range from 2 to 25 percent gravel. Redoximorphic features range from 2 to 25 percent soft oxidized iron masses. Reaction ranges from strongly acid to slightly acid.
The Bt horizon dry color is 7.5YR 5/6, 6/4, 6/6, 7/4, 5YR 5/6, 6/4 or 6/6. Moist color is 7.5YR 3/4, 4/4, 4/6, 5YR 3/4, 4/4, 4/6 or 5/4. Texture is gravelly sandy loam, sandy clay loam, gravelly sandy clay loam, loam or clay loam. Clay content ranges from 18 to 33 percent. Organic matter ranges from 0.1 to 0.5 percent. Rock fragments range from 5 to 30 percent gravel. Redoximorphic features range from 0 to 5 percent soft oxidized iron masses and 0 to 2 percent soft manganese masses. Reaction ranges from strongly acid to neutral.
The 2Bt horizon dry color is 2.5YR 5/6, 5YR 5/6, 6/4, 6/6, 7.5YR 5/4 or 6/6. Moist color is 2.5YR 4/6, 5YR 4/4, 4/6 or 5/4. Texture is gravelly clay, clay, sandy clay or silty clay. Clay content ranges from 43 to 50 percent. Organic matter ranges from 0 to 0.5 percent. Rock fragments range from 2 to 30 percent gravel. Redoximorphic features range from 0 to 2 percent soft manganese masses. Reaction ranges from moderately acid to neutral.
The 3Bqm horizon is indurated to weakly cemented, becoming less cemented with greater depth and may have a silica and manganese capping up to 1/8 inch, (3 mm) thick. Rock fragments range from 10 to 50 percent gravel. Redoximorphic features range from 10 to 90 percent manganese surface coats on the upper surface.
COMPETING SERIES: There are no other series in this family.
GEOGRAPHIC SETTING: Thermalito soils are on mounds on intermediate terraces. Slopes range from 0 to 9 percent. These soils formed in alluvium from metamorphic and igneous rocks such as quartz, chert, quartz-diorite, greenschist, diorite, tuff, andesite and basalt. Elevation is 110 to 258 feet, (33 to 79 m). Mean annual precipitation is 20 to 26 inches, (508 to 660 mm). The mean annual temperature is 60 to 62 degrees F, (16 to 17 degrees C). Frost free season is 250 to 255 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Fernandez, Oroville and Thompsonflat soils. Fernandez soils are very deep to weakly to moderately cemented duripan, the 2Bt horizon extends to a depth of 60 inches, (152 cm) or more and clay does not decrease by 20 percent from the maximum at a depth of 60 inches (152 cm). Oroville soils are moderately deep to duripan, are fine and are in swales. Thompsonflat soils are very deep, are fine-loamy, clay content decreases by 20 percent from the maximum at a depth of 60 inches, (152 cm).
DRAINAGE AND PERMEABILITY: Somewhat poorly drained; very high runoff; moderately rapid saturated hydraulic conductivity in the A horizon, moderate to moderately slow in the Bt horizon, slow in the 2Bt horizon and impermeable in the 3Bqm horizon. A fluctuating water table can occur from the top of the duripan to 14 inches, (36 cm) below the surface of the soil from December through April.
USE AND VEGETATION: This soil is used for livestock grazing, wildlife habitat, home site development and in some areas, olive orchards. Vegetation is soft chess, wild oat, filaree, medusahead, ripgut brome, red brome, mouse barley, Italian ryegrass, clover, vetch, bluedicks, purple clarkia, pepperweed, blue stars and popcornflower.
DISTRIBUTION AND EXTENT: Butte County California and occurs in (262Ag) Hardpan Terraces subsection of the (262A) Great Valley section. MLRA: 17 - Sacramento Valley. The soils are inextensive. Associated with the Laguna formation.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Butte County, California 2005. Source of name from Thermalito Afterbay.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - zone from 0 to 2 inches, (0 to 5 cm) (A)
Argillic horizon - zone from 2 to 32 inches, (5 to 81 cm) (Bt1, Bt2, Bt3, Bt4, Bt5, 2Bt6, 2Bt7)
Abrupt textural change - zone from 25 to 32 inches, (63 to 81 cm) (2Bt6, 2Bt7)
Duripan - zone from 32 to 60 inches, (81 to 152 cm)
Particle-size control section for this pedon: 2 to 22 inches, (5 to 56 cm).
The soil moisture control section - zone from 9 to 26 inches, (23 to 66 cm) is dry in all parts from about June to October (about 180 days).