LOCATION WATTERSON CAEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, mesic Pachic Haploxerolls
TYPICAL PEDON: Watterson sandy loam - on a slope of less than 1 percent at 6,900 feet elevation under big sagebrush, Douglas rabbitbrush and antelope bitterbrush vegetation. Colors are for dry soil unless otherwise stated. When described October 31, 1978 the soil was dry throughout. 10 percent of the soil surface is covered with fine and medium pebbles.
A1--0 to 8 inches; brown (10YR 5/3) sandy loam, very dark grayish brown (10YR 3/2) moist; weak fine subangular blocky structure; soft, very friable, nonsticky and nonplastic; common very fine and few fine and medium roots; common very fine interstitial pores; 3 percent pebbles; slightly acid (pH 6.1); clear wavy boundary. (5 to 10 inches thick)
A2--8 to 35 inches; brown (10YR 5/3) very gravelly sandy loam, brown (10YR 3/3) moist; weak fine angular blocky structure; hard, very friable, nonsticky and nonplastic; few fine and medium roots; common very fine interstitial pores; 35 percent pebbles, and 15 percent cobbles; slightly acid (pH 6.1); abrupt smooth boundary. (20 to 30 inches thick)
2C--35 to 60 inches; light yellowish brown (2.5Y 6/4) sand, dark yellowish brown (10YR 4/4) moist; single grain; loose, nonsticky and nonplastic; few very fine roots; many fine interstitial pores; 2 percent pebbles; neutral (pH 7.0).
TYPE LOCATION: Mono county, California. About 2 miles west of Crowley Lake and 4 miles east-northeast of Mammoth Airport; 200 feet north and 250 feet east of the southwest corner of section 33, T.3 S., R.29 E., M.D,B.M., Mount Morrison quadrangle.
RANGE IN CHARACTERISTICS: Depth of the soil is 60 inches or more. The particle-size control section averages 35 to 60 percent rock fragments, mainly pebbles and cobbles. The soil between depths of 8 and 30 inches is usually dry from about May 30 to November 15, and is moist in some or all parts the rest of the time. The soil temperature is above 41 degrees F from about April 1 to December 20, and is above 47 degrees F from about April 15 to November 30. The mean annual soil temperature is 47 to 58 degrees F. The soil reaction is slightly acid to neutral.
The A horizon color is 10YR 3/3, 4/2, 4/3, 5/3; or 5YR 5/3. Moist color is 10YR 3/2, 3/3; or 5YR 3/3. Textures are sandy loam, gravelly loamy sand, gravelly sandy loam and very gravelly sandy loam. Rock fragment content is 2 to 15 percent in the upper part and 35 to 60 percent in the lower part. Structure is weak subangular and angular blocky, single grain, or massive. The organic carbon content is 0.6 to 1.0 percent.
The C horizon color is 10YR 5/3, 5/4, 6/3; 2.5Y 6/4 or 5YR 5/3. Moist color is 10YR 4/3, 4/4; 2.5Y 4/4 or 5YR 3/3. Textures are sand, very gravelly sandy loam or very cobbly sand. Strata of loamy sand or gravelly sandy loam are present in some areas. Clay content averages 8 to 15 percent between 10 to 40 inches. Rock fragment content averages 35 to 60 percent consisting of 20 to 60 percent pebbles and 5 to 20 percent cobbles. Some strata in the C horizon lack rock fragments. Structure is weak angular blocky, massive, or single grain. Stony substratum phases are recognized with textures of extremely stony loamy sand and sandy loam with 20 to 30 percent stones.
COMPETING SERIES: These are the Karoc(T) and Wiskiflat(T) series. Karoc soils have a mean annual soil temperature of 48 to 52 degrees F and are neutral to slightly alkaline. The Wiskiflat soil has a mean annual soil temperature of 55 to 59 degrees F.
GEOGRAPHIC SETTING: Watterson soils are on alluvial fans and lake terraces. The parent material is mixed alluvium with volcanic ash and with much granitic influence. Some of the soils near the Sierran moraines may have formed in glacial outwash. Slopes range from 0 to 30 percent. The elevation ranges from 5,500 to 7,500 feet. The mean annual precipitation is 8 to 12 inches, and the mean annual temperature is 45 to 55 degrees F. The mean January temperature is about 29 degrees F; the mean July temperature is about 66 degrees F. The frost-free season is about 105 to 140 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Buscones(T) and Cashbaugh(T) soils. Buscones soils are sandy and moderately deep over hard tuffaceous sandstone or conglomerate on hills and terraces. Cashbaugh soils are sandy and shallow over hard, tuffaceous sandstone or conglomerate on lake terraces.
DRAINAGE AND PERMEABILITY: Well drained; slow and medium runoff; moderately rapid over rapid permeability. In some pedons the permeability is moderately rapid. Irrigated soils are very poorly drained.
USE AND VEGETATION: Used for grazing and wildlife habitat. Vegetation is mainly big sagebrush, antelope bitterbrush, Indian ricegrass, and western needlegrass.
DISTRIBUTION AND EXTENT: East-central California. The soils are of small extent.
MLRA OFFICE RESPONSIBLE: Reno, Nevada
SERIES PROPOSED: Mono County, California; Benton-Owens Valley Soil Survey, 1987.
REMARKS: Diagnostic horizons and features recognized in the profile are:
1. Mollic epipedon -- 0 to 35 inches (A)
1.1 Color values meet mollic criteria. (10YR 5/3).
Other Soil Characteristics:
1. Lacks diagnostic subsoil horizons because:
1.1 No clay films, no segregated lime, no pedogenic structure.
2. The textural control section averages 35 to 60 percent rock fragments.
3. The soil moisture regime is aridic-xeric. It is dry for about 165 days and is above 41 degrees F for about 260 days. It is dry greater than half the time the soil temperature is above 41 degrees F.
4. The soil temperature regime is on the cool end of mesic. M.A.S.T. is 47 to 58 degrees F. This is extrapolated from actual temperature transect data over the past years using Rod Arkley`s equation.
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.