LOCATION SHELD CA
Established Series
RD: JJN/GMK/TDC
12/2022
SHELD SERIES
The Sheld series consists of deep, well drained soils that formed in volcanic ash deposits over colluvium and material weathered from tuff, tuff breccia, or extrusive igneous bedrock. Sheld soils are on mountains and have slopes of 9 to 65 percent. The mean annual precipitation is about 35 inches and the mean annual temperature is about 42 degrees F.
TAXONOMIC CLASS: Ashy-skeletal, mixed, frigid Alfic Vitrixerands
TYPICAL PEDON: Sheld stony sandy loam - on an east facing convex slope of 34 percent under white fir, ponderosa pine and manzanita at 6,400 feet elevation. (Colors are for dry soil unless otherwise noted. When described (9/23/73) the soil was moist above 20 inches and dry below.)
Oi--0 to 2 inches; fresh and partially decomposed needles, leaves, twigs, bark and other organic debris.
A1--2 to 4 inches; brown (10YR 4/3) stony sandy loam, dark reddish brown (5YR 3/2) moist; weak fine granular structure; soft, very friable, nonsticky and nonplastic; many very fine, fine and medium roots; many very fine and fine interstitial pores; 10 percent pebbles, 5 percent cobbles and 4 percent stones; weakly smeary; strongly acid (pH 5.5); clear smooth boundary. (1 to 3 inches thick)
A2--4 to 9 inches; brown (10YR 5/3) stony sandy loam, dark reddish brown (5YR 3/3) moist; weak fine granular structure; soft, very friable, nonsticky and nonplastic; many very fine, fine and medium roots; many very fine and fine random interstitial pores; 10 percent pebbles, 5 percent cobbles and 4 percent stones; weakly smeary; slightly acid (pH 6.5); clear wavy boundary. (3 to 7 inches thick)
A3--9 to 21 inches; brown (7.5YR 5/2) gravelly sandy loam, dark reddish brown (5YR 3/3) moist; very weak medium subangular blocky structure; soft, very friable, nonsticky and nonplastic; many very fine, fine and medium roots; many very fine and fine random interstitial pores; 20 percent pebbles, 5 percent cobbles and 2 percent stones; weakly smeary; slightly acid (pH 6.5); gradual irregular boundary. (6 to 12 inches thick)
AB--21 to 29 inches; brown (7.5YR 5/2) very gravelly sandy loam, dark reddish brown (5YR 3/3) moist; very weak medium subangular blocky structure; slightly hard, very friable, nonsticky and nonplastic; many very fine, fine and medium roots; few very fine, and fine tubular pores; 40 percent pebbles, 5 percent cobbles and 5 percent stones; moderately smeary; moderately acid (pH 6.0); gradual wavy boundary. (6 to 10 inches thick)
Bt--29 to 35 inches; reddish gray (5YR 5/2) very gravelly sandy loam, dark reddish brown (5YR 3/3) moist; weak fine subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; many medium and common very fine and fine roots; few very fine and fine tubular pores; few thin clay films in pores and on peds; 40 percent pebbles, 5 percent cobbles and 5 percent stones; moderately smeary; moderately acid (pH 6.0); clear wavy boundary. (4 to 8 inches thick)
2Btb1--35 to 42 inches; reddish gray (5YR 5/2) very gravelly loam, dark reddish brown (5YR 3/3) moist; weak fine subangular blocky structure; hard, friable, slightly sticky and slightly plastic; many medium, and common very fine roots; few very fine and fine tubular pores; common thin clay films in pores and on peds; 40 percent cobbles, and 5 percent stones; moderately acid (pH 6.0); clear wavy boundary. (6 to 10 inches thick)
2Btb2--42 to 48 inches; weak red (2.5YR 5/2) very gravelly loam, dark reddish brown (2.5YR 2/4) moist; weak fine subangular blocky structure; hard, slightly firm, sticky and plastic; common very fine and fine, and many medium roots; few very fine and fine tubular pores; common thin clay films in pores and on peds; 40 percent pebbles, 5 percent cobbles and 5 percent stones; moderately acid (pH 6.0); clear wavy boundary. (6 to 10 percent inches thick)
2Cr--48 to 62 inches; weak red (2.5YR 5/2) dark reddish brown (2.5YR 2/4) moist; horizon about 60 percent saprolite and 30 percent hard andesite. Soil fills cracks and seams.
TYPE LOCATION: Siskiyou County, California; about 20 miles NE of Weed on Hwy 97 on the eastern slopes of Miller Mountain or about 1/2 miles east of Herd Peak Lookout; about 400 feet south on a dirt logging road from an intersection and about 90 feet west from the dirt road; about 2,600 feet south and 145 feet east of the NW corner section 29, T.44 N., R.3 W.
RANGE IN CHARACTERISTICS: The volcanic ash mantle is 20 to 40 inches thick. Depth to a paralithic contact of weathered basalt is 40 to 60 inches. The mean annual soil temperature is 42 degrees to 47 degrees F. The soil temperature exceeds 41 degrees F. from May 1 to November 10 and exceeds 47 degrees F. from June 1 to October 20. The soil is dry in the 8-to 24-inch control section from mid-July to mid-October and is moist in some or all parts the rest of the year. The bulk density ranges from 0.6 to 1 g/cc to a depth of 10 to 20 inches but is 0.85 g/cc or more at a depth of 10 to 14 inches. The umbric epipedon is 7 to 12 inches thick.
The A horizon dry colors are (10YR 4/2, 4/3, 4/4, 5/2, 5/3; 7.5YR 4/2, 4/4, 5/2). Moist colors are (10YR 2/2, 3/2, 3/3; 7.5YR 3/2; 5YR 3/2; 5YR 2/2, 3/2, 3/3). It is very stony or stony sandy loam in the A1 and A2 and gravelly sandy loam in the A3, with about 5 to 10 percent clay content. Rock fragments range from 15 to 35 percent. The rock fragments consist of stones, cobbles, and gravel. It is slightly acid to strongly acid and the base saturation ranges from 40 to 60 percent but is less than 50 percent in at least part of the upper 10 inches. The NaF pH ranges from 9.8 to 10.6 and commonly is highest at the surface.
The Bt horizon colors are (7.5YR 5/2, 5/4, 6/2, 6/4; 5YR 5/2, 5/3, 5/4, 6/2, 6/3, 6/4). Moist colors are (5YR 3/3, 4/3). It is very gravelly sandy loam or very gravelly loam with about 6 to 12 percent clay content. There commonly are a few thin clay films in the lower part in most pedons. There is only 1 or 2 percent increase in clay over the A horizon. Rock fragments range from 35 to 60 percent and consist mostly of gravel with some stones and cobbles. It is slightly acid or medium acid and the base saturation ranges from 30 to 60 percent. The NaF pH is about 9.0 to 9.5.
The 2Btb horizon colors are (7.5YR 5/2, 5/4, 6/2; 5YR 5/2, 5/3, 5/4, 6/2; 2.5YR 5/2, 5/4). Moist colors are (7.5YR 3/2, 4/2, 4/4; 5YR 3/2, 3/3, 3/4, 4/2. 4/3, 4/4; 2.5YR 2/4. 3/2, 3/4, 5/2, 4/4). It is very gravelly sandy loam or very gravelly loam with about 10 to 20 percent clay content. Rock fragments range from 35 to 60 percent and consist mostly of gravel with some stones and cobbles. It is slightly acid, strongly acid and the base saturation ranges from 50 to 65 percent. The NaF pH ranges from 8.5 to 9.0. This horizon has slightly less influence from amorphous materials.
COMPETING SERIES: These are the
Kingtain,
Pheeney,
Tumac,
Waca and
Windy series in the same family and the
Iller series. Pheeney and Waca soils have bedrock at depths of 20 to 40 inches and lack buried Bt horizons. Tumac soils have greater than 60 percent vitric pyroclastic material in the upper 14 inches of the sol. Windy soils lack buried Bt horizons. Iller soils have a medial over loamy-skeletal control section.
GEOGRAPHIC SETTING: Sheld soils are on mountains where more recent volcanic ash has been deposited over materials weathering from tuff, tuff breccia, or hard andesite or basaltic bedrock. Slopes are 9 to 65 percent. These soils have formed in the more recent ash deposits. Elevations are 4,500 to 7,500 feet. The climate is continental and subhumid with warm nearly dry summers and cold moist winters. Mean annual precipitation is 20 to 45 inches. Snowfall is 24 to 48 inches and covers the higher elevations from late November to early April in most years. Mean January temperature is 22 degrees to 30 degrees F.; mean July temperature is 59 degrees to 65 degrees F; mean annual temperature is 37 degrees to 45 degrees F. Frost-free season is 35 to 70 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Avis,
Bogus,
Esro,
Oosen,
Orset,
Pinehurst and the competing
Iller soils. Avis and Oosen soils have an ochric epipedon and ashy-skeletal or ashy control section. Bogus soils have a thick mollic epipedon and fine textured argillic horizon. Esro soils have an aquic moisture regime and a fine-silty control section. Orset soils have an ochric epipedon and have a coarse-loamy control section. Pinehurst soils have a thick mollic epipedon and fine-loamy argillic horizon.
DRAINAGE AND PERMEABILITY: Well drained, medium to very rapid runoff, and moderate permeability.
USE AND VEGETATION: Used mainly for timber. Native vegetation is mainly white fir, with red fir, ponderosa pine, Douglas-fir, incense cedar, snowbrush, prostrate ceanothus, manzanita and bottlebrush squirrel tall.
DISTRIBUTION AND EXTENT: Slopes of older volcanic peaks in northern California and possibly in southern Oregon. The series is moderately extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Siskiyou County, California, 1978.
REMARKS:
Last revised by the state on 2/86.
ADDITIONAL DATA: Sample for characterization 6/74 by the Riverside Laboratory. Pedon No. S74CA-093-7.
National Cooperative Soil Survey
U.S.A.