Established Series


The Montara series consists of shallow well drained soils that formed in material weathered from serpentinitic rocks. Montara soils are on uplands and ridge tops and have slopes of 5 to 75 percent. The mean annual precipitation is about 28 inches and the mean annual air temperature is about 60 degrees F.

TAXONOMIC CLASS: Loamy, magnesic, thermic Lithic Haploxerolls

TYPICAL PEDON: Montara clay loam - annual grasses and forbs. (Colors are for dry soil unless otherwise stated.)

A1--0 to 2 inches; dark gray (10YR 4/1) clay loam, black (10YR 2/1) moist; moderate fine and medium granular structure; hard, friable, sticky and plastic; few fine roots; many fine and very fine pores; common small serpentine fragments; moderately alkaline (pH 8.0); clear wavy boundary (0 to 2 inches thick)

A2--2 to 6 inches; very dark gray (10YR 3/1) clay loam, black (10YR 2/1) moist; moderate medium subangular blocky structure; hard, very friable, sticky and plastic; common very fine roots; many very fine and fine pores; few krotovina; many small and medium stone fragments; moderately alkaline (pH 8.0); clear wavy boundary. (4 to 10 inches thick)

A3--6 to 13 inches; very dark gray (10YR 3/1) clay loam, black (10YR 2/1) moist; moderate fine subangular blocky structure; hard, friable, sticky and plastic; few very fine roots; common fine and very fine pores; many small and medium sized fragments of serpentine; moderately alkaline (pH 8.0); abrupt irregular boundary. (4 to 8 inches thick)

R--13 to 20 inches; greenish gray (5BG 5/1) serpentine.

TYPE LOCATION: Santa Clara County, California; Edenvale Hills near Morgan Hill; 1/2 mile north of Pigeon Point on a private farm road to the O'Connel Ranch, T. 8 S., R. 3 E.

RANGE IN CHARACTERISTICS: Depth to hard bedrock is 10 to 20 inches. Mean annual soil temperature is 59 degrees to 64 degrees F. and the soil temperature usually is not below 47 degrees F. at any time. Soil below a depth of about 4 inches is dry in all parts from May or June to November and is moist in all parts from December to April. Rock fragments are mostly pieces of serpentine rock and they make up 1 to 35 percent of the volume. In most pedons, fragments are less than 15 percent. Sand-size particles are mostly pieces of serpentine rock. The soils are neutral to moderately alkaline, but do not contain free lime. The calcium magnesium ratio is 1:1 or less.

The A horizon is 10YR 3/1, 4/1, 5/1, 3/2, 4/2, 4/3, 5/2, 5/3; 2.5Y 4/2 or 5/2. Moist color is 10YR 2/1, 3/1, 2/2, 3/3 or 3/2; or 2/5Y 3/2. Texture is sandy loam, loam or clay loam and has 18 to 35 percent clay. It may have gravelly or stony modifiers. It has moderate to strong subangular blocky structure and in some pedons some granular structure is present.

Some pedons have a C horizon that has a moist value of 4 and is up to 4 inches thick.

COMPETING SERIES: These are the Climara, Delpiedra, Dubakella, Hambright, Henneke, Lopez, Permanente, and Plaskett series in other families. Climara soils are fine textured and have slickensides. Delpiedra and Dubakella soils have argillic horizons. Hambright, Lopez, Permanente, and Plaskett soils have more than 35 percent rock fragments. Also, Permanente and Plaskett soils have a mean annual soil temperature of 55 degrees to 58 degrees F. Henneke soils have an argillic horizon with more than 35 percent rock fragments.

GEOGRAPHIC SETTING: Montara soils are on rounded ridge tops and uplands at elevations of 100 to 3,000 feet. Slopes are 5 to 75 percent. The soils formed in material weathered from serpentine. The climate is subhumid with hot dry summers and cool moist winters. Mean annual precipitation is 12 to 50 inches. Average January temperature is about 49 degrees F., average July temperature is about 68 degrees F., and the mean annual temperature is 55 degrees to 62 degrees F. The freeze-free season is about 150 to 300 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Climara and Henneke soils and the Diablo, Los Osos, Millsholm, ant Vallecitos soils. Diablo soils are deep clays with slickensides. Los Osos soils are 24 to 40 inches deep to rock and have an argillic horizon. Millsholm soils have an ochric epipedon and have mixed mineralogy. Vallecitos soils have an argillic horizon that is discontinuous within a pedon.

DRAINAGE AND PERMEABILITY: Well drained; medium and high runoff; moderately slow permeability. Seep areas adjacent to rock outcrops may persist for several months after the end of the rainy season.

USE AND VEGETATION: Used mainly for grazing, wildlife, and recreation. Natural vegetation is annual grasses and forbs with a few perennial grasses such as purple stipa. North slopes may have scattered leather oak with yucca on some south slopes.

DISTRIBUTION AND EXTENT: Coast Range of central and northern California. The soils are moderately extensive.


SERIES ESTABLISHED: Alameda County, California 1942.

OSED scanned by SSQA.

National Cooperative Soil Survey