LOCATION HENHILL CAEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, mesic Pachic Argixerolls
TYPICAL PEDON: Henhill silt loam-on a northeast facing 2 percent slope under a cover of basin wildrye, beardless wildrye, sedge and rush at an elevation of 3310 feet. (Colors are for dry soil unless otherwise stated. When described July 16, 1981, the soil was moist throughout.)
A1--0 to 3 inches; dark gray (10YR 4/1) silt loam, very dark gray (10YR 3/1) moist; strong very fine granular structure; slightly hard, very friable, nonsticky and slightly plastic; many very fine roots; many very fine interstitial pores; neutral (pH 7.0); clear smooth boundary.
A2--3 to 12 inches; dark gray (10YR 4/1) silt loam, black (10YR 2/1) moist; moderate fine subangular blocky structure; slightly hard, very friable, nonsticky and slightly plastic; many very fine and common fine roots; few very fine and common fine tubular pores; few fine distinct brown (7.5YR 4/4) masses of iron accumulation; slightly alkaline (pH 7.5); clear wavy boundary.
A3--12 to 21 inches; dark gray (10YR 4/1) silt loam, black (N2/0) moist; moderate medium subangular blocky structure; slightly hard, friable, nonsticky and slightly plastic; common very fine and fine roots; common fine tubular pores; common fine distinct brown (7.5YR 4/4) masses of iron accumulation; moderately alkaline (pH 8.0); clear wavy boundary. (Combined thickness of the A horizon is 20 to 25 inches)
Bt1--21 to 31 inches; dark gray (10YR 4/1) silty clay loam, black (N2/0) moist; moderate fine subangular blocky structure; slightly hard, friable, nonsticky and slightly plastic; common very fine and few fine roots; common fine tubular pores; common thin clay films on peds and in pores; common fine distinct dark reddish brown (5YR 3/2) masses of iron accumulation; moderately alkaline (pH 8.0); clear wavy boundary.
Bt2--31 to 41 inches; brown (7.5YR 5/4) silty clay loam, dark brown (7.5YR 3/2) moist; moderate fine subangular blocky structure; hard, firm, slightly sticky and slightly plastic; common very fine and few fine roots; common fine tubular pores; many moderately thick clay films on peds and in pores; many fine faint dark reddish brown (5YR 3/2) masses of iron accumulation; moderately alkaline (pH 8.0); clear smooth boundary. (Combined thickness of the Bt horizon is 18 to 27 inches)
Bt3--41 to 46 inches; pinkish gray (7.5YR 6/2) silty clay loam, dark brown (7.5YR 3/2) moist; moderate fine angular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; few fine roots; common fine tubular pores; many moderately thick clay films on peds and in pores; slightly effervescent, disseminated lime; many fine faint dark brown (7.5YR 4/2) masses of iron accumulation; moderately alkaline (pH 8.0); clear smooth boundary. (5 to 15 inches thick)
C--46 to 62 inches; light gray (10YR 7/2) silt loam, dark grayish brown (2.5Y 4/2) moist; moderate coarse subangular blocky structure, hard, firm, nonsticky and slightly plastic; few fine roots; few fine tubular pores; slightly effervescent, disseminated lime; many fine faint dark brown (7.5YR 4/2) masses of iron accumulation; moderately alkaline (pH 8.0). (17 to 20 inches thick)
TYPE LOCATION: Shasta County, California; about 1.6 miles northwest of Fall River Mills, 100 feet northwest of PG and E intake dam; 50 feet west and 2,300 feet south of the northeast corner of sec. 26, T. 37 N., R. 4 E., Fall River Mills SW (Fall River Mills) quadrangle (7.5 minute series).
RANGE IN CHARACTERISTICS: Mollic epipedon thickness is 20 to 31 inches. These soils are saturated at a depth of 20 to 60 inches from November through April due to a seasonal water table. Depth to stratified alluvial deposits is 40 to greater than 60 inches. The mean annual soil temperature is 47 to 52 degrees F. The soil temperature exceeds 41 degrees F. from early March to late December (300 days) and exceeds 47 degrees F. from early April to early December. The soil moisture control section (6 to 17 inches) is dry in all parts from early July to mid October (110 days) and is moist in all parts from mid November to early May. The particle-size control section ranges from 27 to 35 percent clay. Electrical conductivity ranges from 0 to 2 mmhos/cm. Some pedons have Ak horizons or lack Btk horizons.
The A horizon color is 10YR 4/1, 5/1 or N5/0; faint or distinct mottles are 7.5YR 5/4. Moist color is 10YR 2/1, 3/1 or N2/0; faint or distinct mottles are 7.5YR 4/4. Organic matter ranges from 4 to 7 percent. Clay content ranges from 18 to 27 percent. Reaction is neutral to moderately alkaline. Base saturation by sum of cations ranges from 90 to 100 percent. It is noneffervescent to slightly effervescent and lime is disseminated.
The Bt1 and Bt2 horizon color is 10YR 4/1, 5/1, 5/2, 6/1, 6/2, 7/2; 7.5YR 5/4 or 6/2; faint to prominent mottles are 5YR 3/4, 7.5YR 4/4 or 10YR 4/4. Moist color is 10YR 3/1, 3/2, 4/2; 7.5YR 3/2, 4/2 or N2/0; faint to prominent mottles are 5YR 3/2 or 7.5YR 4/4. Organic matter ranges from 1 to 4 percent. Clay content ranges from 27 to 35 percent. Reaction is moderately alkaline to strongly alkaline. Base saturation by sum of cations ranges from 90 to 100 percent. It is noneffervescent to slightly effervescent and lime is disseminated.
The Bt3 horizon color is 10YR 6/1, 6/2 or 7.5YR 6/2; faint to prominent mottles are 7.5YR 4/6 or 10YR 5/4. Moist color is 10YR 3/1, 3/2, 4/1, 4/2 or 7.5YR 3/2; faint to prominent masses of iron accumulation are 7.5YR 4/2 or 10YR 4/4. Clay content ranges from 27 to 35 percent. It is slightly to violently effervescent, lime is disseminated.
The C horizon color is 10YR 7/2, 8/1 or 7/1; distinct mottles are 7.5YR 4/6. Moist color is 10YR 5/1, 6/2; 5Y 4/2 or 2.5Y 4/2; distinct mottles are 7.5YR 4/2. Texture is silt loam, sandy loam, sandy clay loam or very gravelly sandy clay loam. Clay content ranges from 15 to 27 percent. Rock fragments, mostly gravel, range from 0 to 60 percent. It is slightly effervescent with disseminated lime.
COMPETING SERIES: These are the Adieux (CA), Banning (OR), Blockhouse (T WA), Coolbrith (CA), Dotta (CA), Drews (CA), Gorman (CA), Grosswell (T CA), Harriman (OR), Haysum (CA), Lonkey (T CA), Pumphouse (T WA), Robinette (T OR), Supan (CA), Van Dusan (ID), Waha (WA), Wapinitia (OR), Wockum (T WA), and Yaxon (WA) soils. Adieux, Lonkey and Waha soils are 20 to 40 inches deep to lithic contact. Banning soils have neutral reaction in the control section and have MAST of 52 to 56 degrees F. Blockhouse soils are moderately well drained have neutral reaction in the control section and are dry for 45 to 60 consecutive days. Coolbrith soils do not have Btk horizons. Dotta soils have sandy loam and sandy clay loam textures and have neutral reaction. Drews and Harriman soils have paralithic contact at 40 to 60 inches. Gorman soils have moderately to slightly acid reaction and have MAST of 57 degrees F. Haysum soils have MAST of52 to 59 degrees F. Pumphouse soils are not saturated and are dry for 75 to 90 days. Robinette and Wapinitia soils have lithic contact at 40 to 60 inches and have neutral reaction in the control section. Supan soils have lithic contact at 30 to 48 inches and have neutral reaction in the control section. Van Dusen soils have MAST greater than 59 degrees F. Grosswell, Ricecross and Wockum soils are ...
GEOGRAPHIC SETTING: Henhill soils are on stream terraces adjacent to rivers or creeks. Slopes are 0 to 2 percent. These soils formed in lake sediments and alluvium extrusive from igneous rock. Elevation is 3,300 to 4,600 feet. The climate is subhumid with warm dry summers and cold moist winters. Mean annual precipitation is 12 to 20 inches. Snowfall is 24 to 48 inches. The mean annual temperature is 48 to 52 degrees F. The mean January temperature is about 32 degrees F. The mean July temperature is about 68 degrees F. Frost-free season is 100 to 130 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Dotta, Pastolla (T), and Pit soils. Pastolla soils have a water table above 40 inches, have a aquic moisture regime and have a thin histic epipedon on low stream terraces and in basins. Pit soils have clay or silty clay textures to 40 inches and are on flood plains and in basins.
DRAINAGE AND PERMEABILITY: Somewhat poorly drained; slow to ponded runoff; moderately slow permeability. The soils are occasionally flooded for periods of 7 days to greater than 1 month in November to April. A water table occurs at depths of 20 to 60 inches from November through April.
USE AND VEGETATION: This soil is mainly used for crops and pasture. The natural vegetation is beardless wildrye, carex, rush, kentucky bluegrass, alpine timothy, meadow foxtail. Soils are cropped to alfalfa or grass hay.
DISTRIBUTION AND EXTENT: Lassen, Modoc and Shasta Counties California. The soils are moderately extensive. MLRA is 21.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Shasta County, Intermountain Soil Survey Area, California 1994. Source of name is coined.
REMARKS: This series was close to being an aquoll but the watertable depth was greater than 20 inches and the mollic went to a depth of 41 inches. Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - 0 to 41 inches (A1, A2, A3, Bt1, Bt2)
Argillic horizon - 21 to 46 inches (Bt1, Bt2, Bt3)
The superactive cation exchange activity class was added in 03/2003 to the taxonomic classification by the National Soil Survey Center on request of the Reno MLRA office, without review of the soil series property data. The remainder of this document has not been updated.