LOCATION FRANCISQUITO CAEstablished Series
TAXONOMIC CLASS: Fine, mixed, active, thermic Typic Haploxeralfs
TYPICAL PEDON: Francisquito loam; on a south facing slope at 420 feet in elevation. (Colors are for dry soil unless otherwise noted. When described September 20, 1984, the soil was moist below 21 inches).
Ap--0 to 6 inches; light yellowish brown (10YR 6/4) loam, dark yellowish brown (10YR 4/4) moist; moderate fine and medium subangular blocky structure; hard, firm, slightly sticky and slightly plastic; common very fine roots; many very fine and fine tubular and interstitial, and few medium tubular pores; slightly acid (pH 6.2); clear, irregular boundary. (4 to 8 inches thick)
A1--6 to 16 inches; light yellowish brown (10YR 6/4) loam, dark yellowish brown (10YR 4/4) moist; weak medium and coarse subangular blocky structure; hard, firm, slightly sticky and slightly plastic; few very fine roots; many very fine tubular and interstitial, and few medium tubular pores; slightly acid (pH 6.2); clear, irregular boundary. (8 to 15 inches thick)
Bt1--16 to 21 inches; variegated light yellowish brown (10YR 6/4) and brown (7.5YR 4/4) clay loam, dark yellowish brown (10YR 4/4) moist; weak medium and coarse subangular blocky structure; very hard, firm, slightly sticky and slightly plastic; few very fine roots; many very fine and fine tubular and interstitial pores; few thin clay films on peds and in pores; slightly acid (pH 6.2); clear, irregular boundary. (5 to 10 inches thick)
Bt2--21 to 26 inches; variegated yellowish brown (10YR 5/6) and strong brown (7.5YR 5/6) clay loam; dark yellowish brown (10YR 4/6) and strong brown (7.5YR 5/6) moist; weak medium and coarse subangular blocky structure; very hard, firm, slightly sticky and slightly plastic; few very fine roots; many very fine and fine tubular and interstitial pores; common thin clay films on peds and in pores; slightly acid (pH 6.2); clear, irregular boundary. (5 to 10 inches thick)
Bt3--26 to 34 inches; variegated light yellowish brown (10YR 6/4) and strong brown (7.5YR 5/6) clay; dark yellowish brown (10YR 4/6) moist; weak coarse subangular blocky structure; extremely hard, firm, slightly sticky and slightly plastic; few very fine roots; many very fine and fine tubular and interstitial pores; many thin clay films on ped faces and in pores; moderately acid (pH 5.7); clear, irregular boundary. (6 to 12 inches thick)
Bt4--34 to 50 inches; pale brown (10YR 6/3) and brown (7.5YR 5/4) clay; variagated brownish yellow (10YR 6/6) and dark brown (7.5YR 4/4) moist; weak coarse subangular blocky structure; extremely hard, firm, slightly sticky and slightly plastic; few very fine roots; many very fine and fine tubular and interstitial pores; many thin clay films on ped faces and in pores; moderately acid (pH 5.7); clear, irregular boundary. (10 to 20 inches thick)
BC--50 to 60 inches; very pale brown (10YR 8/3) clay loam; brownish yellow (10YR 6/6) moist; massive, very hard, slightly sticky and slightly plastic; many very fine and fine tubular and interstitial pores; moderately acid (pH 5.7).
TYPE LOCATION: San Mateo County, California; about 1,200 feet north on Sand Hill Road from intersection with Mountain Home Road; 200 feet east of Sand Hill Road. (Palo Alto 7.5' Quadrangle) USGS. This area does not have sections.
RANGE IN CHARACTERISTICS: The thickness of the solum is 50 to 60 inches. The mean annual soil temperature is about 60 to 62 degrees F. The soil between the depths of 6 and 18 inches is moist throughout from December 1 to June and dry throughout from July to mid October. Base saturation is greater than 75 percent in the upper 34 inches.
The A horizons has dry color of 10YR 6/2, 6/3, 6/4, 7/2, 7/3, or 7/4, and moist color of 10YR 4/2, 4/3, 4/4, 5/2, 5/3, or 5/4. It is slightly acid to moderately acid.
The B horizon has dry color of 10YR 5/6, 6/3, 6/4, 6/5, 6/6; 7.5YR 4/4, 5/4, or 5/6, and moist color of 10YR 4/4, 4/6, 5/6; 7.5YR 3/4, 4/4, 4/6, 5/4, or 5/6. It is clay loam or clay. It is slightly acid to moderately acid.
COMPETING SERIES: These are the Artois and Los Banos series. Artois series are mildly alkaline in the subsoil. Los Banos series are mildly to moderately alkaline throughout with soft lime masses.
GEOGRAPHIC SETTING: Francisquito soils are on terraces and have slopes of 5 to 15 percent. They formed in alluvium dominantly from mixed sources. Elevation ranges from 400 to 500 feet. The climate is subhumid mesothermal with warm dry summers and cool moist winters. The mean annual precipitation is about 25 to 35 inches. The mean January temperature is about 48 degrees F; mean July temperature is about 65 degrees F; and the mean annual temperature is about 57 degrees F. The frost-free season is about 270 to 330 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Accelerator (T), Fagan, and Botella soils. Accelerator and Fagan soils are 40 to 60 inches to a paralithic contact. Botella soils have a mollic epipedon and are fine-loamy.
DRAINAGE AND PERMEABILITY: Well drained; slow to medium runoff; slow permeability.
USE AND VEGETATION: These soils are used as wildlife habitat and urbanland. The vegetation is soft chess, wild oats, other annual grasses, forbs, and scattered hardwoods.
DISTRIBUTION AND EXTENT: These soils are on terraces of south eastern San Mateo County. The soils are not extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: San Mateo County, California 1985. Name is from San Francisquito Creek.
REMARKS: The activity class was added to the classification in January of 2003. Competing series were not checked at that time. - ET