LOCATION ROUNDVAL CA

Established Series
Rev. VB-ET-JJJ-MAV
06/2016

ROUNDVAL SERIES

The Roundval series consists of very deep, somewhat poorly and poorly drained soils that formed in alluvium from mixed rock sources. Roundval soils are on alluvial fans. Slopes are 0 to 5 percent. The mean annual precipitation is about 180 mm and the mean annual temperature is about 16 degrees C.

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.

A1--0 to 5 cm; dark grayish brown (2.5Y 4/2) mucky loam, black (2.5Y 2.5/1) 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. (3 to 5 cm thick)

A2--5 to 28 cm; very dark grayish brown (2.5Y 3/2) loam, black (N 2/0) moist; moderate medium prismatic structure; slightly hard, friable, moderately sticky and moderately plastic; many very fine, common fine and few medium roots; common very fine and fine tubular and interstitial pores; 2 percent gravel; slightly acid (pH 6.4); clear wavy boundary. (23 to 38 cm thick)

Bw--28 to 46 cm; 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 moderately plastic; common very fine and fine and few medium roots; common very fine tubular and interstitial pores; 5 percent gravel; neutral (pH 6.8); clear wavy boundary. (15 to 25 cm thick)

C1--46 to 117 cm; olive gray (5Y 5/2) sandy clay loam, dark olive gray (5Y 3/2) moist; common medium distinct, olive (5Y 4/3) 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 gravel; neutral (pH 7.0); clear wavy boundary. (51 to 76 cm thick)

C2--117 to 152 cm; gray (5Y 6/1) clay loam, dark greenish gray (5GY 4/1) moist; massive; hard, firm, moderately sticky and moderately plastic; few very fine and fine roots; common very fine and fine tubular pores; common fine prominent, dark yellowish brown (10YR 4/6) masses of iron accumulations lining pores and surrounding roots; 10 percent gravel; 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.; USGS Rovana 7.5 minute topographic quadrangle; latitude 37 degrees 24 minutes 45 seconds N and longitude 118 degrees 34 minutes 08 seconds W; WGS84 Decimal Degrees 37.4125 latitude, -118.5688889 longitude.

RANGE IN CHARACTERISTICS: The thickness of the mollic epipedon is 60 to 150 cm. The mean annual soil temperature is 12.8 to 15 degrees C. (see remarks). The 25 to 100 cm control section averages 20 to 30 percent clay. Thin strata of sandy loam are common below 46 cm. Redoximorphic features are common below a depth of 45 cm. The water table is between 30 to 91 cm deep from February to May.

The A1 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 A2 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 1,345 to 1,435 meters. The climate is characterized by warm dry summers and cool moist winters with some snowfall. The mean annual precipitation is 100 to 200 mm and the mean annual temperature is 15 to 17 degrees C. 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 61 cm 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 SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California

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 117 cm (A1, A2, Bw, C1 horizon).
Cumulic subgroup - The mollic epipedon is more than 61 cm thick (0 to 117 cm) (A1, A2, Bw, C1 horizon).
Aquic moisture regime - The water table has been observed within 41 cm of the surface, matrix chroma of 1 and 0 in the top two mineral layers, presence of redoximorphic features below 46 cm.

National Cooperative Soil Survey
U.S.A.