LOCATION GLENBLAIR CAEstablished Series
TAXONOMIC CLASS: Fine-loamy, parasesquic, isomesic Typic Argiudolls
TYPICAL PEDON: Glenblair gravelly loam - on an east facing slope of 55 percent under redwood, Douglas-fir, swordfern and oxalis at 640 feet elevation. (Colors are for dry soil unless otherwise stated. When described on November 13, 1979, the soil was moist throughout).
Oi--2 inches to 0; litter of redwood.
A--0 to 10 inches; dark reddish gray (5YR 4/2) gravelly loam, dark reddish brown (5YR 3/2) moist; strong very fine and fine granular structure; hard, very friable, slightly sticky and slightly plastic; common medium and few very fine and fine roots; common very fine and few fine interstitial pores; 20 percent pebbles (2-25mm); neutral (pH 7.0); clear irregular boundary. (8 to 16 inches thick)
Bt1--10 to 22 inches; dark reddish gray (5YR 4/2) gravelly clay loam, dark reddish brown (5YR 3/2) moist; moderate medium and coarse granular structure; hard, very friable, slightly sticky and plastic; common medium and coarse, and few very fine and fine roots; common very fine and few fine interstitial pores; common thin clay films on faces of peds and lining pores; 25 percent pebbles (2-75mm) and 5 percent cobbles (75-125mm); slightly acid (pH 6.2); gradual wavy boundary. (8 to 16 inches thick)
Bt2--22 to 39 inches; dark reddish gray (5YR 4/2) gravelly clay loam, dark reddish brown (5YR 3/2) moist; moderate medium and coarse subangular blocky structure parting to fine and medium granular; hard, friable, slightly sticky and plastic; common medium and coarse and few fine roots; common very fine and few fine interstitial pores; common thin clay films on faces of peds and lining pores; 20 percent pebbles (2-75mm) and 10 percent cobbles (75-125mm); slightly acid (pH 6.2); gradual wavy boundary. (15 to 18 inches thick)
Bt3--39 to 62 inches; dark reddish gray (5YR 4/2) very gravelly clay loam, dark reddish brown (5YR 3/2) moist; moderate medium and coarse subangular blocky structure parting to fine and medium granular; hard, friable, slightly sticky and plastic; common coarse and few fine and medium roots; common very fine and few fine interstitial pores; many moderately thick clay films on faces of peds and lining pores; 30 percent pebbles (2-75mm) and 10 percent cobbles (75-125mm); slightly acid (pH 6.1); abrupt irregular boundary. (8 to 24 inches thick)
R--62 to 67 inches; dark reddish gray (5YR 4/2) hard fractured meta-basalt; fractures are 5 to 8cm apart and are 1 to 5mm wide; continuous moderately thick clay films on fracture faces.
TYPE LOCATION: Mendocino County, California; about 100 feet downhill on the north side of Sherwood Road, at a point about 3.3 miles east of its intersection with Highway 1; about 250 feet south and 600 feet west of the northeast corner of sec. 10, T.18N., R.17W., Comptche NW quadrangle.
RANGE IN CHARACTERISTICS: Depth to lithic contact and thickness of the solum is 40 to 70 inches. The mean annual soil temperature is 50 to 56 degrees F. The difference between mean summer and mean winter soil temperature is 3 to 6 degrees F. The soil between the depths of 8 and 26 inches is moist in all parts from November 1 to August 15 and is dry in some part from September 1 to October 1 in most years. The particle-size control section averages 30 to 35 percent clay and 20 to 35 percent coarse fragments. Base saturation (ammonium acetate) ranges from 65 to 95 percent throughout.
The A horizon is 5YR 4/2, 4/3 or 2.5YR 3/2. Moist color is 5YR 3/2, 3/3 or 2.5YR 3/2. Gravel content is 15 to 25 percent. Organic carbon content ranges from 2 to 6 percent, decreasing regularly with increasing depth. Reaction is slightly acid or neutral.
The Bt horizon is 5YR 4/2, 4/3, 5/3; 2.5YR 4/2 or 4/4. Moist color is 5YR 3/2;, 3/3; 2.5YR 3/2 or 3/3. It is gravelly clay loam, very gravelly clay loam, gravelly clay or very gravelly clay with 27 to 45 percent clay. Gravel content ranges from 15 to 50 percent. Cobble content ranges from 0 to 10 percent. Organic carbon content ranges from 0.6 to 2.5 percent, decreasing regularly with increasing depth. Reaction is moderately or slightly acid.
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING: Glenblair soils are on hills. Slopes are 9 to 75 percent. Elevations are 100 to 800 feet. The soils formed in material weathered from metamorphosed basalt. The climate is humid with cool foggy summers and cool moist winters. A strong marine influence limits the annual and diurnal range in temperature. Mean annual precipitation ranges from 40 to 70 inches. Mean January temperature is about 50 degrees F., mean July temperature is about 55 degrees F. and the mean annual temperature is about 53 degrees F. The frost-free period is 290 to 365 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Dehaven, Hotel, Irmulco, Tramway, and Vandamme soils. All of these formed from sandstone, have mixed mineralogy and lack a mollic epipedon.
DRAINAGE AND PERMEABILITY: Well drained; surface runoff under bare soil conditions is rapid through very rapid; moderately slow permeability.
USE AND VEGETATION: This soil is used for timber production, wildlife habitat, watershed and as a source of hard rock. Vegetation consists of redwood, Douglas-fir, tanoak, huckleberry, swordfern and oxalis.
DISTRIBUTION AND EXTENT: Northern coastal California. The series is not extensive. MLRA 4.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Mendocino County, California, Western Part, 1993.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon -- the zone from 0 to 62 inches (A, Bt1, Bt2, Bt3)
Argillic horizon -- the zone from 10 to 62 inches (Bt1, Bt2, Bt3)
Many areas now mapped as Glenblair soils were mapped as Comptche soils by the California Soil Vegetation Survey 1947-1950.