LOCATION GONZAGA CAEstablished Series
TAXONOMIC CLASS: Fine, mixed, superactive, thermic Typic Palexerolls
TYPICAL PEDON: Gonzaga loam - on a north-facing slope of 50 percent, under blue oak, California buckeye and annual grasses and forbs at an elevation of 790 feet. (Colors are for dry soil unless otherwise stated. When described on July 1, 1981, the soil was slightly moist below 16 inches.)
A1--0 to 7 inches; yellowish brown (10YR 5/4) loam, dark brown (10YR 3/3) moist; moderate medium and coarse subangular blocky structure; slightly hard, friable, sticky and plastic; common very fine and few fine and medium roots; common very fine, few fine, and common medium and coarse tubular pores; 10 percent gravel 2 to 15 mm in size; 4.1 percent organic matter; 22 percent clay content; neutral (pH 6.8); clear smooth boundary.
A2--7 to 16 inches; yellowish brown (10YR 5/4) loam, dark brown (10YR 3/3) moist; moderate medium subangular blocky structure; slightly hard, friable, sticky and plastic; common very fine, many fine, and common medium tubular pores; 10 percent gravel 2 to 15 mm in size; 2.8 percent organic matter; 21 percent clay content; neutral (pH 7.0); clear smooth boundary. (Combined thickness of the A horizon is 10 to 20 inches)
ABt--16 to 22 inches; brown (7.5YR 5/4) gravelly sandy clay loam, dark brown (7.5YR 3/4) moist; moderate medium subangular blocky structure; hard, friable, sticky and plastic; few very fine, fine, and medium roots; common very fine and fine tubular pores; few thin clay films line pores; 25 percent gravel and cobbles 2 to 130 mm in size; 24 percent clay content; neutral (pH 7.0); abrupt wavy boundary. (0 to 8 inches thick)
Bt1--22 to 31 inches; yellowish red (5YR 4/6) dry and moist gravelly sandy clay; moderate medium prismatic structure parting to strong medium angular blocky; hard, firm, very sticky and plastic; few very fine, fine, medium, and coarse roots; few very fine and fine tubular pores; common thick clay films bridging sand grains; many thick pressure faces; 20 percent angular gravel 2 to 20 mm in size; 41 percent clay content; neutral (pH 7.3); clear smooth boundary. (5 to 10 inches thick)
Bt2--31 to 39 inches; strong brown (7.5YR 5/6) dry and moist gravelly sandy clay; moderate coarse angular blocky structure; hard, firm, very sticky and plastic; few very fine, fine, medium and coarse roots; few very fine and fine tubular pores; many thick clay films line pores; 25 percent angular gravel 2 to 25 mm in size; 40 percent clay content; neutral (pH 7.3); clear irregular boundary. (3 to 11 inches thick)
R1--39 to 43 inches; yellowish red (7.5YR 5/6) slightly weathered, strongly fractured siltstone with very little soil material in fractures, few fine medium, and coarse roots along fracture plane; many thick clay films on rock fragments; no rotational displacement of the rock fragments; clear wavy boundary. (3 to 8 inches thick)
R2--43 inches; strongly fractured unweathered siltstone.
TYPE LOCATION: Merced County, California; about 14 miles west of the city of Los Banos, 3,700 feet north of Highway 152, 310 feet north of firebreak road, 3,000 feet south and 2,400 feet west of the SE corner of section 34, T.9 S., R.7 E.
RANGE IN CHARACTERISTICS: Mollic epipedon thickness is 10 to 20 inches. Depth to a lithic contact is 20 to 40 inches. The moisture control section of 7 to 20 inches is moist throughout from about November 15 to June 1 and dry throughout from about July 1 to October 15 in most years. The soil temperature is below 47 degrees F from December 15 to March 1. The mean annual soil temperature is 59 to 64 degrees F. Organic matter content ranges from 1 to 5 percent in the upper 10 inches of the soil. The clay content of the Bt horizon is 15 to 30 percent (absolute) more than the A horizon.
The A horizon is 5YR 5/3; 7.5YR 5/2, 5/4; 10YR 4/3, 5/1, 5/2, 5/3, or 5/4. Moist colors are 5YR 3/3; 7.5YR 3/2; 10YR 3/1, 3/2, or 3/3. Clay content is 15 to 27 percent. Rock fragments are 0 to 15 percent gravel. Reaction is slightly acid or neutral. The boundary is clear or abrupt.
The ABt horizon, when present, is 5YR 5/4; 7.5YR 5/4, 6/4; or 10YR 5/2, 5/3, 5/4. Moist colors are 5YR 3/4; 7.5YR 3/2, 3/4; or 10YR 3/2, 3/3, 3/4. Texture is clay loam, sandy clay loam, loam, gravelly loam or gravelly sandy clay loam with 15 to 30 percent clay content and 5 to 30 percent gravel and cobbles.
The Bt horizon is 5YR 4/6, 5/3, 5/4, 5/6; 7.5YR 4/6, 5/4, or 5/6. Moist colors are 2.5YR 3/6; 5YR 4/2, 4/3, 4/4, 4/6, 5/4, 5/6; 7.5YR 4/4, 4/6, 5/4, or 5/6. Texture is clay, sandy clay, clay loam, gravelly sandy clay, gravelly clay, or gravelly clay loam and has 35 to 55 percent clay content. Rock fragments are 5 to 30 percent angular gravel and cobbles. Reaction is neutral or slightly alkaline.
COMPETING SERIES: There are no other series in this family.
GEOGRAPHIC SETTING: Gonzaga soils are on mountains and have slopes of 30 to 75 percent. These soils typically occur on northern exposures. Elevations range from 500 to 3,600 feet. The soils formed in material weathered from sedimentary and metasedimentary rocks of the Franciscan Formation. The climate is subhumid with warm dry summers and cool moist winters. The mean annual precipitation is about 10 to 24 inches. Mean January temperature is 44 degrees F; mean July temperature is 72 degrees F. The mean annual temperature is about 59 to 61 degrees F. Frost-free period is 190 to 260 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Contra Costa, Fifield, Franciscan, Honker, Millsholm, Quinto and Sehorn soils. Contra Costa soils have an ochric epipedon. Fifield soils are loamy-skeletal. Franciscan soils are fine-loamy. Millsholm and Quinto soils are less than 20 inches deep to a lithic contact. Sehorn soils lack an argillic horizon and develop wide cracks upon drying.
DRAINAGE AND PERMEABILITY: Well drained; very high runoff; very slow permeability.
USE AND VEGETATION: These soils are used for livestock grazing and upland wildlife habitat. The vegetation is blue oak, California buckeye, wild oats, soft chess, red brome and foxtail fescue.
DISTRIBUTION AND EXTENT: These soils are in the Coast Range of California. They are not extensive in MLRA-15.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Merced County, California, 1983.
REMARKS: These soils were formerly mapped as Rough stony land and Vallecitos stony clay loam in the Los Banos Area, series 1939 report. They are being differentiated from the Vallecitos series by being moderately deep and having a mollic epipedon.
Diagnostic horizons and features recognized in this pedon are:
--Mollic epipedon - the zone from 0 to 16 inches (A1, A2)
--Argillic horizon- the zone from 22 to 39 inches (Bt1, Bt2)
--Lithic contact - the boundary at 39 inches (R1, R2)
CEC/Clay ratio estimated from similar soils with laboratory data in the W. Stanislaus Soil Survey Area.
Runoff terminology of rapid or very rapid, adjusted 9/96 to adjective criteria of very hig from the Soil Survey Manual, 10/93.