LOCATION ATTER CAEstablished Series
TAXONOMIC CLASS: Sandy-skeletal, mixed, mesic Typic Xerorthents
TYPICAL PEDON: Atter very cobbly sandy loam - on a slope of 1 percent under annual forbs and grasses and scattered ponderosa pine at 2,890 feet elevation. (Colors are for dry soil unless otherwise stated. When described February 5, 1974, the soil was moist throughout).
A1--0 to 9 inches; dark grayish brown (10YR 4/2) very cobbly sandy loam, very dark gray (10YR 3/1) moist; massive; soft, very friable, slightly sticky and nonplastic; many very fine, fine and medium roots; few fine interstitial and tubular pores; 25 percent pebbles and 25 percent cobbles; slightly acid (pH 6.5); abrupt smooth boundary. (4 to 11 inches thick).
A2--9 to 12 inches; pale brown (10YR 6/3) very cobbly sandy loam, very dark grayish brown (10YR 3/2) moist; massive; soft, very friable, slightly sticky and nonplastic; common very fine, fine and many medium roots; few fine interstitial and tubular pores; 25 percent pebbles and 25 percent cobbles; slightly acid (pH 6.5); abrupt wavy boundary. (3 to 14 inches thick).
AC--12 to 18 inches; pale brown (10YR 6/3) very cobbly sandy loam, dark brown (10YR 3/3) moist; massive; soft, very friable, slightly sticky and nonplastic; common very fine, fine and many medium roots; common fine interstitial and tubular pores; 25 percent pebbles and 25 percent cobbles; slightly acid (pH 6.5); abrupt wavy boundary. (0 to 14 inches thick).
C1--18 to 33 inches; pale brown (10YR 6/3) very cobbly loamy sand, dark brown (10YR 4/3) moist; single grained; loose, few very fine, fine and common medium roots; common fine interstitial pores; 25 percent pebbles and 25 percent cobbles; moderately acid (pH 6.0); abrupt wavy boundary. (4 to 20 inches thick)
C2--33 to 60 inches; light brownish gray (10YR 6/2) very cobbly sand, dark grayish brown (10YR 4/2) moist; single grained; loose; common fine interstitial pores; 30 percent pebbles and 20 percent cobbles; moderately acid (pH 6.0).
TYPE LOCATION: Siskiyou County, California; 1.5 miles southwest of Greenview on Kidder Creek Road; 420 feet southwest of the northeast corner or 265 feet south and 320 feet west of the northeast corner sec. 36, T. 43 N., R. 10 W.
RANGE IN CHARACTERISTICS: The mean annual soil temperature is 52 to 59 degrees F. The soil temperature is above 41 degrees F from March through November and is above 47 degrees F from April through October. The soil is dry between 10 and 45 inches from July 15 to October 15 and moist in some or all parts during the rest of the year. Rock fragments are stream rounded and are 35 to 75 percent throughout the profile, but average less than 60 percent in the control section. The fragments commonly consist of equal amounts of gravel and cobbles. The size of the rock fragments increases toward the apex of the fans. Boulders 2 to 3 feet in diameter in the profile and on the surface are common near the apex of the larger fans. The soil ranges from neutral to moderately acid. The upper 10 to 20 inches of the control section averages between 0 and 5 percent clay and from 70 to 95 percent fine sand or coarser. However, the average clay content in the control section ranges from 2 to 8 percent.
The A horizon is 2.5Y 6/2, 7/4, 10YR 4/2, 4/3, 5/2, 5/3, 6/2, 6/3. Moist colors are 2.5Y 5/2, 5/4, 10YR 3/1, 3/2, 4/1, 4/2 or 4/3. The organic carbon content of the upper 7 inches of the A horizon averages less than 0.6 percent and decreases regularly with depth. It is sandy loam to loamy sand and is modified by 30 to 80 percent rock fragments ranging from gravel to boulders in size.
The C horizon is 10YR 4/2, 4/3, 4/4, 5/2, 5/3, 5/4, 6/2, 6/3, 6/4, 6/6; 7.5YR 6/6, 5/8, 6/8. Moist colors are 10YR 3/3, 3/4, 4/2; 7.5YR 4/6, 5/6. It is sand or loamy sand and may be very cobbly or very bouldery with discontinuous thin lenses or pockets of silt loam or sandy loam in some pedons.
COMPETING SERIES: These are the Carlsborg, Choop (T), Cowlitz (T), Hoypus, Spens and Valcreek (T) series. Carlsborg and Hoypus soils have Bs horizons. The Cowlitz soils contain 10 to 30 percent volcanic glass and are dry only 60 to 75 days. Spens soils have mean annual soil temperature of 47 to 51 degrees F. Valcreek soils are 20 to 40 inches deep over a paralithic contact.
GEOGRAPHIC SETTING: Atter soils are on alluvial fans and low stream terraces at elevations of 2,000 to 5,000 feet. The soils formed in recent mixed alluvium derived from metamorphic rocks. Atter soils have bar and channel topography. Boulders and stones are common on the surface near the apex of fans. Elevations are 1,300 to 3,200 feet for the gravelly and cobbly phases and 3,000 to 5,000 feet for the bouldery phases. The climate is continental and subhumid with warm dry summers and cold moist winters. Mean annual precipitation is 16 to 40 inches. Seasonal snowfall is 12 to 24 inches. Mean January temperature is 34 degrees F; mean July temperature is 71 degrees F; mean annual temperature is 50 to 57 degrees F. Frost-free season is 100 to 180 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Bonnet, Esro, Kinkel, Marpa, Serpa and Stoner soils. Bonnet soils have a mollic epipedon and moderately alkaline and strongly effervescent Bk horizon. Esro soils have an aquic moisture regime and a fine-silty control section. Kinkel and Marpa soils have argillic horizons and are underlain by bedrock. Serpa soils have an aquic moisture regime and a fine textured argillic horizon. Stoner soils have a coarse-loamy control section and a cambic horizon.
DRAINAGE AND PERMEABILITY: Somewhat excessively drained; slow to medium runoff; rapid permeability.
USE AND VEGETATION: Used for woodland and grazing. Forage production is very low. Vegetation is ponderosa pine, Jeffrey pine, incense cedar, manzanita, buckbrush, bitterbrush, Idaho fescue, Thurber needlegrass and bottlebrush squirreltail.
DISTRIBUTION AND EXTENT: Mountain valleys of Northern California. The soil is not extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Siskiyou County, California, 1978.
REMARKS:
Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - the zone from the surface to 18 inches (A1, A2, and AC horizons).
Particle-size control section - the zone from 10 to 40 inches (A2, AC, C1, and C2 horizons).