LOCATION HILT CAEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, mesic Mollic Haploxeralfs
TYPICAL PEDON: Hilt sandy loam - on an east facing convex slope of 17 percent under buckbrush, cheatgrass, juniper and Oregon white oak at 2,840 feet elevation. (Colors are for dry soil unless otherwise stated. When described (5/24/66) the soil was dry above 11 inches and moist below.)
A11--0 to 2 inches; brown (10YR 5/3) sandy loam, very dark grayish brown (10YR 3/2) moist; weak medium platy structure; slightly hard, friable, slightly sticky and slightly plastic; many fine roots; many fine tubular pores; neutral (pH 6.7); abrupt smooth boundary. (1 to 2 inches thick)
A12--2 to 6 inches; brown (10YR 5/3) sandy loam, very dark grayish brown (10YR 3/2) moist; moderate medium platy structure; slightly hard, friable, sticky and slightly plastic; many fine and very fine roots; common fine tubular pores; neutral (pH 6.6); abrupt smooth boundary. (2 to 4 inches thick)
A3--6 to 11 inches; dark brown (7.5YR 4/4) sandy loam, dark brown (10YR 3/3) moist; moderate medium platy structure; slightly hard, friable, sticky and plastic; many fine and very fine roots- many fine tubular pores; few thin clay films in pores; slightly acid (pH 6.4); clear wavy boundary. (2 to 5 inches thick)
B1t--11 to 23 inches; dark brown (7.5YR 4/4) light sandy clay loam, dark yellowish brown (10YR 3/4) rubbed moist; dark brown (7.5YR 3/2) faces of peds moist; weak medium prismatic structure; hard, friable, sticky and very plastic: common fine roots; common fine and medium tubular pores; common thin clay films on peds and in pores; slightly acid (pH 6.4); clear wavy boundary. (6 to 13 inches thick)
B21t--23 to 31 inches; yellowish red (5YR 4/6) sandy clay loam, dark yellowish brown (10YR 3/4) rubbed moist; dark brown (7.5YR 3/4) faces of peds moist; weak medium prismatic structure parting to moderate medium subangular blocky; hard, friable and slightly firm, very sticky and very plastic; few fine roots; common fine and few medium tubular pores; continuous thin and common moderately thick clay films in pores and on peds; neutral (pH 6.6); clear wavy boundary. (6 to 8 inches thick)
B22t--31 to 38 inches; yellowish red (5YR 4/6) sandy clay loam, dark brown (7.5YR 4/4) rubbed moist, dark brown (7.5YR 3/4) faces of peds moist; moderate medium prismatic structure parting to moderate medium subangular blocky; hard, slightly firm, very sticky and very plastic; few fine roots; common fine and few medium tubular pores; continuous thin and moderately thick clay films in pores and on peds; neutral (pH 6.6); clear wavy boundary. (4 to 8 inches thick)
Cr--38 to 47 inches; yellowish red (5YR 4/8) moderately weathered sandstone; crushes to sandy clay loam dark brown (7.5YR 4/4) rubbed moist; structure mostly rock structure; few fine roots in fractures; many thin and common moderately thick clay films on faces of fractures; abrupt wavy boundary. (10 to 30 inches thick)
R--47 to 49 inches; sandstone bedrock with some weathering in cracks and seams. A few fine roots in seams and cracks and continuous moderately thick clay films on rock faces. Some soil in cracks and seams.
TYPE LOCATION: Siskiyou County, California; about 6 miles north of Montague and just west of the Yreka-Ager road; approximately 2,600 feet west and 1,750 feet south of the northeast corner sec. 26, T. 46 N., R. 6 W.
RANGE IN CHARACTERISTICS: The soil is 20 to 40 inches deep to a paralithic contact of weathered sedimentary rock. Hard bedrock is at depths below 40 inches. The mean annual soil temperature commonly is 53 to 56 degrees F. but ranges from 53 to 59 degrees F. The mean January soil temperature is 36 to 39 degrees F.; the mean July soil temperature is 70 to 83 degrees F. The soil temperature exceeds 41 degrees F. from March 1 to December 20 and exceeds 47 degrees F. from April 1 to November 25. The soil between depths of 8 and 18 inches, is dry from mid-July until mid-October in most years and is moist in some or all parts the rest of the year. The organic carbon is less than 0.6 percent when mixed to 7 inches or in some part to a depth of 10 inches. The soil is medium acid to neutral and the base saturation ranges from 80 to 95 percent.
The A1 horizon is brown, dark yellowish brown, yellowish brown or reddish brown (10YR 4l3, 4/4, 5/3, 5/4; 7.5YR 4/4, 5/4; 5YR 4/3, 4/4, 5/3, 5/4). Moist colors are very dark grayish brown, dark brown, dark yellowish brown or dark reddish brown (10YR 3/2, 3/3, 3/4; 7.5YR 3/2, 3/4; 5YR 3/2, 3/3, 3/4). It is loam or sandy loam with 10 to 30 percent clay. Rock fragments range from 0 to 25 percent and consist mostly of stones and cobbles.
The B2t horizon is reddish brown, yellowish red, brown, strong brown or yellowish brown (5YR 4/4, 4/6, 4/8, 5/4, 5/6; 7.5YR 4/4, 5/4, 5/6; 10YR 5/4, 5/6). Moist colors are reddish brown, dark reddish gray, reddish brown, dark brown, dark yellowish brown, dark grayish brown, brown or dark yellowish brown (5YR 3/4, 4/2 4/4; 7.5YR 3/4, 4/2, 4/4; 10YR 3/4, 4/2, 4/3, 4/4). It is heavy loam or sandy clay loam averaging between 20 and 35 percent clay and more than 45 percent total sand. There is at least 4 percent increase in clay from the A horizon to the B1t horizon or B2t horizon. The percent clay increase ranges from 4 to 10 percent and occurs within a distance of 12 inches.
The Cr horizon has the same color, texture and reaction ranges as the B2t horizon but retains about 50 percent of the original rock structure.
COMPETING SERIES: These are the Bancas, Blakeport, Bull Trail, Mary, Morical and Steinbeck series in the same family and the Duzel and Facey series in other families. Bancas soils have soil temperatures above 47 degrees F. by mid-February and are dry about 180 days. Blakeport soils have a mean annual soil temperature of 47 to 52 degrees F. and are medium acid or strongly acid. Bull Trail and Steinbeck soils lack a paralithic contact within 40 inches of the surface. Also, Bull Trail soils have soil temperatures above 47 degrees F. by mid-February and Steinbeck soils have a thick A2 horizon. Duzel soils have a mollic epipedon. Facey soils have a mollic epipedon and lack a lithic or paralithic contact at depths of 20 to 40 inches and have less than 45 percent total sand tn the control section. Morical soils have 20 to 40 percent ash and pumice and are neutral or mildly alkaline.
GEOGRAPHIC SETTING: Hilt soils are on hills and uplands with a dissected terrace-like appearance. Slopes are 2 to 50 percent. The soils formed in material weathered from sedimentary rocks of the Hornbrook Formation that include sandstone and quartzitic conglomerate. Elevations are 2,000 to 3,500 feet. The underlying sedimentary rock is sandstone or sandstone conglomerate that contains well rounded quartzite fragments that are of coarse pebble or cobblestone size. The rock is normally moderately weathered in the upper 10 to 16 inches and gradually becomes hard. The Hilt soils are in a transition zone from grassland to mixed coniferous forest. The climate is continental and subhumid with warm to hot dry summers and cold moist winters. Mean annual precipitation is 14 to 20 inches. Seasonal snowfall is 8 to 36 inches. Mean January temperature is 33 to 37 degrees F., mean July temperature is 67 to 70 degrees F., mean annual temperature is 48 to 52 degrees F. Frost-free season is 100 to 140 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Jilson, Kinkel, Marpa, Stoner, Terwilliger and the competing Duzel and Mary soils. Jilson soils have a mollic epipedon and a lithic contact. Kinkel and Stoner soils have depths greater than 40 inches and have base saturation of less than 75 percent. Kinkel and Marpa soils have more than 35 percent by volume coarse fragments in the control section. Terwilliger soils have a clay Bt horizon and montmorillonitic mineralogy.
DRAINAGE AND PERMEABILITY: Well drained; medium or rapid runoff; moderately slow permeability.
USE AND VEGETATION: Used primarily as rangeland. A few acres are cultivated, both dryland and irrigated. Native vegetation is buckbrush, white oak, yerba-santa, bluebunch wheatgrass, Idaho fescue and Sandberg bluegrass, big sagebrush and some rabbitbrush.
DISTRIBUTION AND EXTENT: North-central California, possibly south-central Oregon. The series is not extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Siskiyou County, California, 1978.
REMARKS: The organic carbon decreases rapidly within a few inches of the surface to less than 0.6 percent. When the moist colors are 3/2 or 3/3 the thickness of the epipedon is too thin to qualify for a mollic epipedon.
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.
ADDITIONAL DATA: Laboratory pedon 566 Calif-47-8 published in S.S.I.R. No. 24 - California. After reexamining the pedon in the field the B3t horizon (38 to 47 inches) was changed to a Cr horizon.
OSED scanned by SSQA. Last revised by state on 10/78.
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.