LOCATION PONTO CAEstablished Series
TAXONOMIC CLASS: Medial, mixed, mesic Typic Vitrixerands
TYPICAL PEDON: Ponto sandy loam, on a southwest facing slope of 4 percent under cut over ponderosa pine and Douglas fir with some incense-cedar and black oak with an understory that was mostly greenleaf manzanita and sierra chinquapin at about 3250 feet elevation. (Colors are for dry soil unless otherwise stated. When described May 26, 1972 the soil was moist throughout.)
Oi--1 inch to 0; recent and partially decomposed needles, leaves, bark and other organic debris; abrupt smooth boundary. (0 to 6 inches thick)
A1--0 to 3 inches; very dark grayish brown (10YR 3/2) sandy loam, black (N2/0) moist; very weak medium platy structure parting to moderate fine granular; soft, very friable, nonsticky and nonplastic; many very fine and fine roots; many very fine and fine interstitial and vesicular pores; 5 percent fine gravel; weakly smeary; strongly acid (pH 5.5); abrupt smooth boundary. (2 to 3 inches thick)
A2--3 to 8 inches; brown (7.5YR 5/4) sandy loam, very dark grayish brown (10YR 3/2) moist; very weak medium subangular blocky structure; soft, very friable, nonsticky and nonplastic; many very fine and fine roots; common very fine and fine interstitial and vesicular pores; 5 percent fine gravel; weakly smeary; strongly acid (pH 5.5); abrupt smooth boundary. (4 to 6 inches thick).
Bw1--8 to 21 inches; light brown (7.5YR 6/4) sandy loam, dark brown (7.5YR 4/4) moist; very weak medium subangular blocky structure; soft, very friable; nonsticky and nonplastic; common very fine and fine, and many medium and coarse roots; common very fine and fine vesicular pores; 10 percent fine (2 to 5 mm) gravel; weakly smeary; strongly acid (pH 5.5); abrupt wavy boundary. (9 to 16 inches thick)
Bw2--21 to 26 inches; pink (7.5YR 7/4) sandy loam, dark brown (7.5YR 4/4) moist; weak medium subangular blocky structure; hard, slightly firm, nonsticky and nonplastic; few very fine and fine, and many medium coarse roots; common very fine and fine vesicular pores; 10 percent fine gravel; weakly smeary; very strongly acid (pH 5.0); abrupt wavy boundary. (3 to 8 inches thick)
BC--26 to 53 inches; very pale brown (10YR 7/4) sandy loam, dark brown (7.5YR 4/4) moist; massive; hard (brittle); slightly firm, nonsticky and nonplastic; few very fine and fine with many medium roots; 5 percent fine gravel; weakly smeary; very strongly acid (pH 5.0); abrupt smooth boundary. (24 to 29 inches thick)
C--53 to 80 inches; light brown (7.5YR 6/4) stony sandy loam, dark brown (7.5YR 4/4) moist; massive; hard (brittle); firm, nonsticky and nonplastic; few very fine, fine and medium roots; common very fine and fine vesicular pores; 10 percent fine gravel, 10 percent stones; weakly smeary; very strongly acid (pH 5.0).
TYPE LOCATION: Siskiyou County, California. About 3 miles southeast of Mt. Shasta, California. About 1600 feet north and 860 feet east of the southwest corner of section 35, T.40N., R.4W., Weed Quadrangle, 15 minute series (city of Mount Shasta Quadrangle, 7.5 minute series).
RANGE IN CHARACTERISTICS: Depth to a consolidated tuff-like layer is greater than 60 inches. Mean annual soil temperature is 52 to 58 degrees F.; mean January soil temperature is about 35 degrees F.; mean July soil temperature is about 70 degrees F. The soil temperature exceeds 41 degrees F. from mid March to mid December and exceeds 47 degrees F. from mid April to mid November. The soil between the depths of 8 to 24 inches is dry for about 70 to 95 days from mid July to mid October in most years and is moist in some or all parts all the rest of the year.
Bulk density ranges from 0.5 to 0.90 g/cc to a depth of 10 to 30 inches.
The A horizon are 10YR 3/2, 3/3, 3/4, 4/2, 4/3, 4/4, 5/2, 5/3, 5/4; 7.5YR 3/2, 3/4, 4/2, 4/4, 5/2, 5/4. Moist colors are N 2/0, N 3/0; 10YR 2/1, 2/2, 3/1, 3/2, 3/3, 3/4; 7.5YR 2/2, 3/2, 3/4; 5YR 3/4, or 3/3. Those colors that are dark lack the thickness to qualify for a mollic or umbric epipedon. It is sandy loam, loam, stony loam or stony sandy loam with about 6 to 15 percent clay content. Rock fragments range from 5 to 35 percent and consists of fine (2 to 5 mm) hard concretions and shot-like gravel, also, gravel to 3 inches in size, cobbles, and stones. It is moderately acid or strongly acid and the base saturation ranges from 15 to 40 percent.
The Bw horizon are 10YR 5/3, 5/4, 6/3, 6/4, 7/4; 7.5YR 4/4, 5/4, 6/4, 7/4; 5YR 5/3, 5/4, 5/6, 6/4, 7/4. Moist colors are 10YR 3/3, 3/4, 4/3, 4/4; 7.5YR 3/4, 4/4, 4/6; 5YR 3/4, 4/3, 4/4, or 4/6. It is sandy loam or loam with 8 to 18 percent clay content. Rock fragments range from 5 to 15 percent and consists of fine (2 to 5 mm) hard concretions and shot-like gravel, also gravel up to 3 inches in size, cobbles and stones. It is moderately acid to very strongly acid and the base saturation is 10 to 30 percent (sum of cations).
The C horizon are 10YR 5/4, 5/6, 6/4, 6/6, 7/4; 7.5YR 5/4, 5/6, 6/4, 7/4; 5YR 5/4, 5/6, 6/4, 7/4. Moist colors are 10YR 3/3, 4/4, 5/4, 5/6; 7.5YR 4/4, 5/4, 5/6; 5YR 4/4, 4/6, 5/4, or 5/6. It is stony sandy loam or stony loam with 10 to 18 percent clay content. Rock fragments range from 15 to 35 percent and consists of small amounts of gravel and cobbles and 10 to 20 percent stones. Most pedons are slightly to strongly brittle.
COMPETING SERIES: There are no other series in this family.
GEOGRAPHIC SETTING: Ponto soils are on hillslopes. Slopes are 2 to 50 percent. The soils formed in volcanic ash deposits over unrelated consolidated tuff-like glacial outwash. Elevations are 2700 to 5000 feet. The climate is subhumid with warm dry summers and cold moist winters. Mean annual precipitation is 30 to 65 inches. Snowfall is 50 to 100 inches. Mean January temperature is 28 to 34 degrees F.; mean July temperature is 64 to 68 degrees F.; the mean annual temperature is 45 to 50 degrees F. Frost-free is 80 to 130 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Deetz, Shasta, and Neer soils. Deetz and Shasta soils have an ashy control section. Also, Shasta soils have an umbric epipedon. Neer soils are on plateaus and mountains and have a medial skeletal control section.
DRAINAGE AND PERMEABILITY: Well drained; slow to rapid runoff; moderate permeability.
USE AND VEGETATION: Used mainly for timber production with some recreation, urban, and wildlife habitat. The vegetation is Douglas fir, white fir, ponderosa pine, sugar pine, incense cedar, black oak, deerbrush, snowbrush ceanothus, bitter cherry, Klamath plum, greenleaf manzanita and mountain whitethorn.
DISTRIBUTION AND EXTENT: Cascade ranges of Northern California. The soils are moderately extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Siskiyou County, California, 1978.
REMARKS: Formerly considered a member of the Manton series, which has a mollic epipedon. The University of California, Davis, has data on a profile within a few feet of this pedon (Pedon #73-CA47-102X). Determinations were made on PSD, B.D., WRD, pH, Extractable Cations, CEC, B.S., and O.C.