LOCATION KRON CAEstablished Series
TAXONOMIC CLASS: Loamy, mixed, superactive, isomesic Lithic Haplustolls
TYPICAL PEDON: Kron sandy loam; on a south-west-facing slope of 20 percent under annual grasses and forbs at 650 feet in elevation. (Colors are for dry soil unless otherwise stated. When described May 11, 1983, the soil was moist throughout.)
A1--0 to 3 inches; brown (10YR 4/3) sandy loam, very dark grayish brown (10YR 3/2) moist; moderate very fine and fine subangular blocky structure; soft, very friable, slightly sticky and slightly plastic; many very fine and few fine roots; many very fine tubular and interstitial pores; 6 percent 2 to 20 mm pebbles; slightly acid (pH 6.5); clear, smooth boundary. (3 to 4 inches thick)
A2--3 to 9 inches; brown (10YR 4/3) loam; dark brown (10YR 3/3) moist; moderate fine subangular blocky structure; soft, very friable, slightly sticky and slightly plastic; common very fine and few fine roots; few very fine and common fine tubular and interstitial pores; 11 percent 2 to 40 mm pebbles; slightly acid (pH 6.5); diffuse, smooth boundary. (5 to 8 inches thick)
A3--9 to 14 inches; brown (10YR 5/3) loam; dark brown (10YR 3/3) moist; moderate very fine to coarse subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; common very fine roots; few very fine tubular and interstitial pores; 5 percent 2 to 12 mm pebbles; moderately acid (pH 6.0); abrupt, smooth boundary. (4 to 8 inches thick)
R--14 inches; hard, fractured sandstone.
TYPE LOCATION: San Mateo County, California; on San Bruno Mountain 2,250 feet east on Guadalupe Canyon Parkway from intersection of Radio Road, and 250 feet north of Guadalupe Canyon Parkway up concrete flume. This area is not sectionized.
RANGE IN CHARACTERISTICS: Depth to a lithic contact is 10 to 20 inches. The mean annual soil temperature is 56 to 58 degrees F and the soil temperature usually is not below 47 degrees F at any time. The difference between mean winter and mean summer temperatures is less than 9 degrees F. Organic matter content is greater than 1 percent throughout the profile. The soil between the depth of 4 to 12 inches is moist throughout the profile from mid-November to June. It is dry in some or all parts the rest of the time but is not dry in all parts for 45 consecutive days. Gravel content ranges from 5 to 15 percent throughout the profile.
The A horizon has dry colors of 10YR 4/2, 4/3, 5/2, or 5/3 and moist colors of 10YR 2/2, 3/2, or 3/3. Textures are loam, sandy loam, or very fine sandy loam. The clay content ranges from 15 to 20 percent. Reaction is slightly to moderately acid.
COMPETING SERIES: This is the Pablo series in the same family, and the Barnabe and Bayview series in other families. Pablo soils have sand and coarse fragments of siliceous shale. Barnabe and Bayview soils are loamy-skeletal.
GEOGRAPHIC SETTING: Kron soils are gently rolling to very steep and have slopes of 5 to 75 percent. They formed in material weathered from hard, fractured sandstone. Elevations are 100 to 1,500 feet. The climate is subhumid mesothermal with cool, foggy summers and cool, moist winters. Mean annual precipitation is 20 to 30 inches. January temperature is about 48 degrees F; mean July temperature is about 60 degrees F; mean annual temperature is about 54 to 56 degrees F. Frost-free season is about 300 to 350 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Barnabe, Buriburi, and Candlestick soils. Buriburi and Candlestick soils are 20 to 40 inches to a lithic contact.
DRAINAGE AND PERMEABILITY: Well drained; medium to very rapid runoff; moderate permeability.
USE AND VEGETATION: Watershed, wildlife, recreation and some homesite development. Vegetation consists of soft chess, little quaking grass, sheep sorrel, narrow leaf plantain, foxtail fescue, and coyote bush.
DISTRIBUTION AND EXTENT: Upland areas of central coastal California that receive summer fog. These soils are of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: San Mateo County, California, 1984.
REMARKS: The major diagnostic horizon is a mollic epipedon. The base saturation is assumed to be greater than 50 percent and the organic matter greater than 1 percent. These assumptions are based on the NSSL reference samples from nearby areas.
The activity class was added to the classification in February of 2003. Competing series were not checked at that time. - ET