LOCATION ROACHA CAEstablished Series
TAXONOMIC CLASS: Fine, smectitic, mesic Typic Argixerolls
TYPICAL PEDON: Roacha silty clay loam on a north-facing slope of 55 percent under pine bluegrass, soft chess, blue oak, juniper and scattered foothill pine. The elevation is 2,100 feet. (Color is for dry soil unless otherwise stated. When described April 10, 1985, the soil was moist throughout.)
A--0 to 4 inches; brown (10YR 5/3) silty clay loam, dark brown (10YR 3/3) moist; strong medium and coarse subangular blocky structure; slightly hard, friable, very sticky and very plastic; many very fine and fine roots; many very fine, fine, tubular and interstitial pores; common moderately thick pressure faces; 5 percent gravel fragments of hard shale 0.25 to 1 inch in size; cracks 1 inch wide at surface; neutral (pH 7.0); clear smooth boundary. (2 to 6 inches thick)
Bt1--4 to 14 inches; brown (10YR 4/3) silty clay, dark brown (10YR 3/3) moist; strong medium angular blocky structure; slightly hard, friable, very sticky and very plastic; many very fine, fine, and common medium roots; many very fine, fine and few medium, tubular and interstitial pores; common moderately thick pressure faces, few moderately thick clay films bridging sand grains; 5 percent gravel fragments of hard shale 0.25 to 1 inch in size; neutral (pH 7.0); clear smooth boundary. (6 to 12 inches thick)
Bt2--14 to 22 inches; dark yellowish brown (10YR 4/4) clay, brown (10YR 4/3) moist; strong fine and medium subangular blocky structure; slightly hard, friable, very sticky and very plastic; few very fine, coarse, and common fine, medium roots; common very fine, fine, medium, tubular and interstitial pores; common moderately thick pressure faces, few moderately thick clay films bridging sand grains; 5 percent gravel fragments of hard shale 0.25 to 1 inch size; cracks 0.25 inch wide; neutral (pH 7.2); clear wavy boundary. (7 to 12 inches thick)
C--22 to 28 inches; yellowish brown (10YR 5/4) and light yellowish brown (2.5Y 6/4) gravelly clay, dark yellowish brown (10YR 3/4) and olive brown (2.5Y 4/4) moist; massive; slightly hard, friable, very sticky and very plastic; common medium and coarse roots; common fine and medium tubular pores; common thin pressure faces; 20 percent gravel fragments of hard shale 0.13 to 0.75 inch in size; slightly effervescent, carbonates disseminated; slightly alkaline (pH 7.5). (5 to 10 inches thick)
Cr--28 to 37 inches; highly fractured soft shale.
TYPE LOCATION: Fresno County, California; 0.65 mile southeast of Los Gatos Creek road and Atlas Mine road gate. About 1,800 feet east of Los Gatos Creek; 900 feet south and 2,300 feet east of the northwest corner of section 30, T. 19 S., R. 13 E., MDB&M; Latitude 36 degrees, 15 minutes, 14 seconds north and Longitude 120 degrees, 36 minutes, 31 seconds west; USGS Santa Rita Peak Topographic Quadrangle, NAD 27.
RANGE IN CHARACTERISTICS: Depth to a paralithic contact of fractured soft and hard shale is 20 to 40 inches. The moisture control section of 7 to 21 inches is moist from December 1 to June 1 and dry from July 1 to September 15 in most years. The soil temperature is above 47 degrees F from April 15 to November 15. The mean annual soil temperature is 54 to 58 degrees F. Clay content in the control section is 40 to 55 percent.O Cracks are as wide as 1 inch in the surface but diminish to 0.25 inch or less within a depth of 20 inches.
The A horizon has color of 10YR 5/2 or 5/3. Moist color is 10YR 3/3 or 3/2. Organic matter content is 1 to 3 percent. Clay content is 30 to 40 percent. Gravel content is 2 to 10 percent. Reaction is neutral or slightly alkaline.
The Bt horizons are 10YR 4/3, 4/4, 5/3, 5/4, 6/4 or 2.5Y 6/4. Moist color is 10YR 3/3, 3/4, 4/3, 4/4 or 2.5Y 4/4. Dry and moist chromas above 3 and moist values above 3 are in the lower part. Organic matter content is 0.7 to 2 percent. Texture is silty clay or clay. Clay content is 40 to 55 percent. Gravel content is 2 to 10 percent. Reaction is neutral or slightly alkaline.
The C horizon is 10YR 5/4, 6/3, 6/4, 6/6 or 2.5Y 6/4. Moist color is 10YR 3/4, 4/3, 4/4, 5/3, 5/4; 2.5Y 4/4 or 5Y 4/4. Organic matter content is 0.4 to 0.8 percent. Texture is gravelly clay loam, gravelly silty clay loam, gravelly clay or gravelly silty clay. Clay content is 35 to 50 percent. Gravel content is 15 to 30 percent. It is slightly effervescent or non-effervescent. Reaction is neutral or slightly alkaline.
COMPETING SERIES: These are the Cranegulch (T), Daphnedale, Keating, Maple Hollow, Midvale, Ramo, and Widmer (T). Cranegulch (MLRA 10) on foothills, Maple Hollow (MLRA 28A) on alluvial fans, Midvale (MLRA 10) on terraces, and Ramo (MLRA 9, 43) on footslopes soils are very deep. Daphnedale soils (MLRA 21) are on terraces and have a paralithic contact composed of soft sedimentary tuff with slopes of 2 to 50 percent that have 46 to 50 degrees F. mean annual soil temperature. Keating soils (MLRA 10) are on hills and have a lithic contact of fractured greenstone. Widmer soils (MLRA 21) are on plateaus and formed in residuum derived from basalt with hard basalt within 60 inches.
GEOGRAPHIC SETTING: Roacha soils are on backslopes of mountains. The soils formed in material weathered from fractured soft and hard shale of the Panoche Formation. Slope is 30 to 65 percent . Elevation is 1,280 to 4,570 feet. The climate is subhumid with hot dry summers and cool moist winters. The mean annual precipitation is 12 to 20 inches. The mean January temperature is 45 degrees F; and the mean July temperature is 79 degrees F. The mean annual temperature is 53 to 58 degrees F. The frost free season is 180 to 230 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Grazer, Lilten, Millsholm, and Vernado. Grazer soils have an ochric epipedon, a thermic temperature regime and have a depth of 40 to 60 inches to a paralithic contact. Lilten soils have an ochric epipedon, a thermic temperature regime, and have a depth of 40 to 60 inches to a paralithic contact. Millsholm soils have a depth of 10 to 20 inches to a lithic contact. Vernado soils have a mollic epipedon greater than 20 inches thick, a coarse-loamy particle-size control section, and have a lithic contact. All of these soils occur on mountains.
DRAINAGE AND PERMEABILITY: Well drained; very high runoff; slow permeability.
USE AND VEGETATION: These soils are used as rangeland, and for recreation and wildlife habitat. The vegetation is pine bluegrass, soft chess, blue oak, juniper and scattered foothill pine.
DISTRIBUTION AND EXTENT: These soils are in the Coast Range of California. They are moderately extensive. MLRA 15.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Fresno County, California, 2000. Named after Roach Canyon.
REMARKS: This series was classified as fine, mixed, mesic Typic Haploxerolls when it was proposed in 1986. Subsequent work supported an argillic horizon and smectitic mineralogy. The pH was determined by colorimetric method using Hellige-Truog Triplex indicators. Texture determined by hydrometer method. Presence of carbonate determined by 10 percent HCL.