LOCATION ROUNDVAL CAEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, mesic Cumulic Endoaquolls
TYPICAL PEDON: Roundval mucky loam, in permanent pasture, on a one percent slope. Colors are for dry soil unless otherwise stated. The soil was moist throughout when described on July 19, 1990.
AO--0 to 2 inches; dark grayish brown (2.5Y 4/2) mucky loam, black (2.5Y 2/2) moist; equal mixture of mineral and highly decomposed organic material; moderate fine and medium subangular blocky and moderate fine granular structure; slightly hard, friable, nonsticky and nonplastic; many very fine and fine roots; many very fine interstitial and common very fine tubular pores; moderately acid (pH 6.0); abrupt wavy boundary. (1 to 2 inches thick)
A--2 to 11 inches; very dark grayish brown (2.5Y 3/2) loam, black (N 2/0) moist; moderate medium prismatic structure; slightly hard, friable, sticky and plastic; many very fine, common fine and few medium roots; common very fine and fine tubular and interstitial pores; 2 percent pebbles; slightly acid (pH 6.4); clear wavy boundary. (9 to 15 inches thick)
Bw--11 to 18 inches; dark gray (5Y 4/1) sandy clay loam, very dark gray (5Y 3/1) moist; weak medium subangular blocky structure; slightly hard, friable, slightly sticky and plastic; common very fine and fine and few medium roots; common very fine tubular and interstitial pores; 5 percent pebbles; neutral (pH 6.8); clear wavy boundary. (6 to 10 inches thick)
C1--18 to 46 inches; olive gray (5Y 5/2) sandy clay loam, dark olive gray (5Y 3/2) moist; common medium distinct (5Y 3/3) masses of iron accumulations lining pores and surrounding roots; massive; slightly hard, friable, slightly sticky and slightly plastic; common very fine and few fine roots; common very fine and fine tubular and interstitial pores; 10 percent pebbles; neutral (pH 7.0); clear wavy boundary. (20 to 30 inches thick)
C2--46 to 60 inches; gray (5Y 6/1) clay loam, dark greenish gray (5GY 4/1) moist; massive; hard, firm, sticky and plastic; few very fine and fine roots; common very fine and fine tubular pores; common fine prominent (10YR 4/6) masses of iron accumulations lining pores and surrounding roots; 10 percent pebbles; neutral (pH 7.0).
TYPE LOCATION: Inyo County, California; in Round Valley, 120 feet north and 150 feet west of the east quarter corner of section 21, T. 6 S., R. 31 E., M.D.B.M., Mount Tom quadrangle.
RANGE IN CHARACTERISTICS: The thickness of the mollic epipedon is 24 to 60 inches. The mean annual soil temperature is 55 to 59 degrees F. (see remarks). The 10 to 40 inch control section averages 20 to 30 percent clay. Thin strata of sandy loam are common below 18 inches. Redoximorphic features are common below a depth of 18 inches. The water table is between 12 to 36 inches deep from February to May.
The AO horizon is 2.5Y 3/2 or 4/2. Moist color is 2.5Y 2/2 or 2/1. Reaction is slightly acid or moderately acid.
The A horizon is 2.5Y 3/2 or 2/2. Moist color is 2.5Y 2/1; N 2/0. Textures are loam, sandy clay loam or sandy loam. Reaction is slightly acid or neutral.
The Bw horizon is 5Y 4/1 or 4/2 or 2.5Y 4/1. Moist color is 5Y 3/1 or 3/2 or 2.5Y 3/1. Textures are sandy clay loam, clay loam or heavy loam. Reaction is slightly acid or neutral.
The C horizon is 5Y 5/2, 4/2, 6/1 or 6/2. Moist color is 5Y 3/2, 4/1, 5/1 or 5/2 or 5GY 4/1 or 5/1. Textures are sandy clay loam or clay loam.
Some pedons do not have the AO horizon.
COMPETING SERIES: These are the Excello, James Canyon and Kimmerling series. Excello series are mapped in areas that receive peak periods of precipitation in the spring and summer. James Canyon and Kimmerling series have a mean annual soil temperature of less than 54 degrees.
GEOGRAPHIC SETTING: Roundval soils are on alluvial fans downslope from faulted areas with springs and seeps. They formed in alluvium from mixed rock sources. Elevations are 4,400 to 4,700 feet. The climate is characterized by warm dry summers and cool moist winters with some snowfall. The mean annual precipitation is 4 to 8 inches and the mean annual temperature is 59 to 63 degrees F. Slopes are 0 to 5 percent. The frost-free season is 140 to 1600 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Conway (T), Dehy (T) and the proposed Mountom soils. The Conway soils are coarse-loamy and usually occur on slightly higher positions on alluvial fans. The Dehy soils are coarse-loamy and have mollic epipedons less than 24 inches thick. They usually occur on lower positions on alluvial fans. The Mountom soils have thick organic layers and are continuously wet. They occur higher on the fan and are associated with springs.
DRAINAGE AND PERMEABILITY: Somewhat poorly and poorly drained; slow runoff; moderately slow permeability; rarely flooded.
USE AND VEGETATION: Roundval soils are used for permanent pasture. Vegetation is predominantly mixed pasture grasses, rushes and sedges.
DISTRIBUTION AND EXTENT: Round Valley of east central California. The series is not extensive in MLRA 29.
MLRA OFFICE RESPONSIBLE: Reno, Nevada
SERIES PROPOSED: Benton-Owens Valley Soil Survey area, Inyo County, California, 1994. The name is coined from Round Valley.
REMARKS: The soil temperature varies widely from the air temperature due to the high water table.
Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - 0 to 46 inches (A), A, Bw, C1)
Cumulic subgroup - The mollic epipedon is more than 24 inches thick (0 to 46 inches)
Aquic moisture regime - The water table has been observed within 16 inches of the surface, matrix chroma of 1 and 0 in the top two mineral layers, presence of redoximorphic features below 18 inches.