LOCATION HOLLOWTREE CAEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, mesic Ultic Haploxeralfs
TYPICAL PEDON: Hollowtree gravelly sandy loam - on an east facing convex slope under Douglas-fir, tanoak and madrone at 3,600 feet elevation. (Colors are for dry soil unless otherwise stated. When described June 3, 1981, the soil was moist throughout.)
Oi--2 inches to 0; undecomposed and partially decomposed litter of tanoak and Douglas-fir within a mulch of hard subrounded sandstone pebbles, 2-75 mm in diameter; About 60 percent of the surface covered with gravel.
A--0 to 6 inches; light yellowish brown (10YR 6/4) gravelly sandy loam, dark yellowish brown (10YR 4/4) moist; moderate fine and medium subangular blocky structure; slightly hard, friable, slightly sticky and nonplastic; common very fine and fine and few medium roots; few very fine and fine tubular and interstitial pores; 20 percent hard subangular pebbles (2 to 75 mm); moderately acid (pH 6.0); clear wavy boundary. (3 to 7 inches thick)
Bt1--6 to 17 inches; very pale brown (10YR 7/4) very gravelly loam, yellowish brown (10YR 5/4) moist; moderate fine and medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; common fine and medium and few coarse roots; few very fine tubular and common very fine interstitial pores; common thin clay films on faces of peds and lining pores; 35 percent hard subrounded pebbles (2 to 75 mm) and 5 percent hard subrounded cobbles (7.5 to 25cm) ; moderately acid (pH 6.0); clear wavy boundary. (6 to 14 inches thick)
Bt2--17 to 27 inches; very pale brown (10YR 7/4) very gravelly sandy clay loam, yellowish brown (10YR 5/4) moist; moderate fine and medium subangular blocky structure; slightly hard, friable, sticky and plastic; common fine and medium and few coarse roots; few very fine tubular and many very fine interstitial pores; common thin and moderately thick clay films on faces of peds and lining pores; 30 percent hard subrounded pebbles (2 to 75 mm) and 10 percent hard angular cobbles (7.5 to 25 cm); moderately acid (pH 6.0); clear wavy boundary. (6 to 14 inches thick)
Bt3--27 to 38 inches; yellow (10YR 7/6) very gravelly sandy clay loam, yellowish brown (10YR 5/6) moist; moderate medium and coarse subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; common medium and few coarse roots; few very fine tubular and many very fine interstitial pores; few thin clay films on faces of peds; 30 percent hard through soft subrounded pebbles (2 to 75 mm) and 5 percent hard subangular cobbles (7.5 to 25 cm); moderately acid (pH 6.0); abrupt irregular boundary. (5 to 12 inches thick)
R--38 to 43 inches; hard fractured sandstone; fractures are less than 1 mm wide and from 5 to 30 cm apart.
TYPE LOCATION: Mendocino County, California; from Branscomb road, take the Cahto Peak access road and turn onto the Stoten Opening road and head to within 100 yards south of the gate. Turn down slope and head 200 yards to the site; 1,400 feet south and 700 feet west of the northeast corner of sec. 7, T. 21 N., R. 15 W. Branscomb quad.
RANGE IN CHARACTERISTICS: Thickness of the solum and depth to a lithic contact ranges from 20 to 40 inches. The mean annual soil temperature ranges from 55 to 59 degrees F. The soil between the depths of 14 inches and the lithic contact is moist in all parts from November 1 through June 1 and is dry in all parts from July 15 through October 1 in most years. The particle-size control section averages from 18 to 27 percent clay.
The A horizon is 10YR 4/2, 5/2, 5/3, 5/4, 6/2, 6/3, 6/4, 7/2, 7/3 or 7/4. Moist color is 10YR 3/2, 3/3, 4/2, 4/3, 4/4, 5/4 or 7.5YR 3/2. Clay content ranges from 10 to 20 percent. Gravel content ranges from 15 to 35 percent, and cobble content ranges from 0 to 5 percent. The A horizon is less than 7 inches thick. Reaction is strongly through slightly acid. Base saturation (sum) ranges from 35 to 60 percent.
The Bt horizon is 10YR 5/4, 5/6, 6/4, 7/3, 7/4, 7/6 or 7.5YR 5/4. Moist color is 10YR 5/4, 5/6, 7.5YR 3/4, 4/4, 5/6 or 5YR 5/4. It is very gravelly sandy loam, very gravelly loam, very gravelly sandy clay loam, gravelly loam or gravelly sandy loam. Clay content ranges from 15 to 27 percent. Gravel content ranges from 25 to 60 percent and cobble content ranges from 0 to 35 percent. Total coarse fragment content ranges from 35 to 60 percent. Reaction is strongly or moderately acid. Base saturation (sum) ranges from 40 to 75 percent.
Some profiles contain a BC or C horizon. Colors are the same as the Bt horizon. It is extremely cobbly sandy loam or extremely gravelly sandy loam with 2 to 20 percent clay and 60 to 80 percent total coarse fragment content.
COMPETING SERIES: These are the Abegg (OR), Asabean (T CA), Behemotosh (T CA), Collayomi (CA), Hambone (T CA), Holohan (CA), Hoosimbim (CA), Marpa (CA), Pendola (CA), Skalan (ID) and Whispering (CA) series. The Abegg, Asabean, Collayomi, Hambone, Holohan, Hoosimbim and Pendola soils are greater than 40 inches deep. Behemotosh soils are not adequately separated at present. Marpa range from 27 to 35 percent clay in the control section. Whispering soils have a mean annual soil temperature of 49 to 54 degrees F. Skalan soils are influenced by ash and have a mean annual soil temperature of 47 to 51 degrees F.
GEOGRAPHIC SETTING: The Hollowtree soils are on mountains. Slopes are 9 to 75 percent. Elevations are 500 to 4,000 feet. The soils formed in material weathered from sandstone. The climate is subhumid with warm dry summers and cool moist winters. Mean annual precipitation is 45 to 130 inches with occasional snowfall above 2,500 feet. Mean January temperature is about 43 degrees F and the mean July temperature is about 70 degrees F. The mean annual temperature is about 55 degrees F. The frost-free period is about 150 to 290 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Holohan soils and the Casabonne, Dann, Pardaloe, Witherell, Wohly, Woodin, and Yorkville soils. Casabonne, Dann, Pardaloe and Yorkville soils are deep or very deep. Casabonne, Witherell, Wohly and Yorkville soil have a nonskeletal control section. Witherell soils are shallow. Dann soils have an oxidic mineralogy. Yorkville soils have a fine textured control section and a thermic soil temperature regime.
DRAINAGE AND PERMEABILITY: Well drained; surface runoff under bare soil conditions is slow to very rapid; moderate permeability.
USE AND VEGETATION: This soil is used for timber and firewood production, wildlife habitat and watershed. Vegetation consists of tanoak, madrone, Douglas-fir, California huckleberry and interior liveoak.
DISTRIBUTION AND EXTENT: Northern coastal California. The series is moderately extensive. MLRA 5.
MLRA OFFICE RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Mendocino County, Eastern Part, California, 1985.
REMARKS: The activity class was added to the classification in February of 2003. Competing series were not checked at that time. - ET
Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - the surface layer from 0 to 6 inches (A horizon)
Argillic horizon - the zone from 6 to 38 inches (Bt1, Bt2, Bt3 horizons)