LOCATION CAPETOWN CA

Established Series
REV: JTB/SAA/ET
07/2016

CAPETOWN SERIES

The Capetown series consists of very deep, moderately well drained soils formed in colluvium derived from sandstone and mudstone. Capetown soils are on mountain slopes. Slopes range from 5 to 30 percent. Mean annual precipitation is about 1520 milimeters and the mean annual temperature is about 11 degrees C.

TAXONOMIC CLASS: Fine-loamy, mixed, superactive, isomesic Aquic Argiustolls

TYPICAL PEDON: Capetown loam on a northeast facing 28 percent slope under grand fir and Douglas-fir with coyote brush, California blackberry, and poison oak in the understory, at an elevation of 134 meters. (Colors are for dry soil unless otherwise noted.) When described on 01/16/09 the soil was moist to 200 centimeters.

Oi--0 to 3 centimeters; slightly decomposed plant material, very dark brown (10YR 2/2) rubbed moist; about 95 percent fiber, 80 percent rubbed; moderately acid, (pH 6.0); abrupt wavy boundary. (0 to 10 centimeters thick)

A1--3 to 14 centimeters; dark grayish brown (10YR 4/2) loam, black (10YR 2/1) moist; moderate fine granular structure; moderately hard, friable, slightly sticky and moderately plastic; many very fine and common fine roots throughout; common very fine tubular and common very fine, fine and medium irregular pores; slightly acid (pH 6.2); clear wavy boundary. (10 to 50 centimeters thick)

A2--14 to 33 centimeters; dark grayish brown (10YR 4/2) loam, black (10YR 2/1) moist; moderate fine granular structure; moderately hard, friable, slightly sticky and moderately plastic; many very fine, fine, medium and common coarse roots throughout; common very fine tubular and common very fine, fine and medium irregular pores; slightly acid (pH 6.2); clear wavy boundary. (0 to 50 centimeters thick)

ABt--33 to 55 centimeters; grayish brown (10YR 5/2) clay loam, very dark brown (10YR 2/2) moist; moderate fine subangular blocky structure; hard, firm, moderately sticky and moderately plastic; common very fine, fine, medium and coarse roots throughout; common very fine tubular pores; 10 percent faint clay films on all faces of peds; moderately acid (pH 5.6); clear wavy boundary. (0 to 50 centimeters)

Bt1--55 to 80 centimeters; light yellowish brown (2.5Y 6/3) clay loam, olive brown (2.5Y 4/3) moist; moderate fine and medium subangular blocky structure; very hard, firm, moderately sticky and very plastic; common very fine, fine, medium and common coarse roots throughout; common very fine tubular pores; 35 percent distinct dark grayish brown (2.5Y 4/2) moist clay films on all faces of peds; 3 percent moderately cemented mudstone paragravel; moderately acid (pH 5.6); clear wavy boundary. (15 to 50 centimeters thick)

Bt2--80 to 95 centimeters; light yellowish brown (2.5Y 6/3) clay loam, olive brown (2.5Y 4/4) moist; moderate fine and medium subangular blocky structure; hard, firm, moderately sticky and very plastic; common very fine, fine, medium and common coarse roots throughout; common very fine tubular pores; 35 percent distinct dark grayish brown (2.5Y 4/2) moist clay films on all faces of peds; 10 percent fine distinct dark gray (2.5Y 4/1) moist iron depletions and 15 percent fine distinct dark yellowish brown (10YR 4/6) moist iron-manganese masses in the matrix; 3 percent moderately cemented mudstone paragravel; moderately acid (pH 5.6); gradual wavy boundary. (0 to 50 centimeters)

Bt3--95 to 140 centimeters; light yellowish brown (2.5Y 6/4) clay loam, olive brown (2.5Y 4/4) moist; moderate fine subangular blocky structure; hard, firm, moderately sticky and moderately plastic; few very fine roots and common very fine and medium roots throughout; common very fine tubular pores; 35 percent distinct olive brown (2.5Y 4/3) moist clay films on all faces of peds; 5 percent fine faint dark gray (2.5Y 4/1) moist iron depletions and 10 percent fine distinct dark yellowish brown (10YR 4/6) moist iron-manganese masses in the matrix; 8 percent moderately cemented mudstone paragravel; moderately acid (pH 5.6); clear wavy boundary. (0 to 50 centimeters thick)

BCt--140 to 200 centimeters; light yellowish brown (2.5Y 6/4) paragravelly clay loam, olive brown (2.5Y 4/4) moist; weak fine subangular blocky structure; hard, firm, moderately sticky and moderately plastic; few very fine and common medium roots throughout; common very fine tubular pores; 10 percent olive brown distinct(2.5Y 4/3) moist clay films on all faces of peds; 5 percent fine distinct dark yellowish brown (10YR 4/6) moist iron-manganese masses in the matrix; 15 percent moderately cemented mudstone paragravel; moderately acid (pH 5.6). (0 to 75 centimeters thick)

TYPE LOCATION: Humboldt County, California; about 7.5 kilometers east of Capetown; USGS Quadrangle Capetown, CA; WGS84 Decimal degrees 40.4528139 latitude, -124.2832583 longitude; UTM zone 10 391187mE, 4478808mN; NAD 83.

RANGE IN CHARACTERISTICS:

Mollic epipedon: 50 to 125 centimeters thick

Particle size control section (weighted average):
Rock fragments: 0 to 35 strongly cemented mudstone and sandstone gravel, 0 to 5 percent strongly cemented sandstone cobbles
Pararock fragments: 0 to 35 percent moderately cemented mudstone and sandstone paragravel
Clay content: 20 to 34 percent

Surface fragments: 0 to 5 percent strongly cemented sandstone gravel

Depth to redoximorphic features: 50 to 100 centimeters

A horizon:
Hue: 10YR or 2.5Y
Value: 4 or 5, 2 or 3 moist
Chroma: 1 to 3, dry or moist
Clay content: 18 to 26 percent
Rock fragments: 0 to 14 percent strongly cemented mudstone and sandstone gravel, 0 to 3 percent strongly cemented sandstone cobbles
Pararock fragments: 0 to 14 percent moderately cemented mudstone paragravel
Reaction: moderately to slightly acid

Upper Bt horizons:
Hue: 10YR or 2.5Y
Value: 6 or 7, 4 or 5 moist
Chroma: 2 to 4, dry or moist
Texture of fine earth: clay loam or silty clay loam
Clay content: 20 to 34 percent
Rock fragments: 0 to 34 percent strongly cemented mudstone and sandstone gravel, 0 to 7 percent strongly cemented sandstone cobbles
Pararock fragments: 0 to 34 percent moderately cemented mudstone paragravel
Reaction: moderately acid

Lower Bt horizons:
Hue: 10YR or 2.5Y
Value: 6 or 7, 4 or 5 moist
Chroma: 3 or 4, dry or moist
Texture of fine earth: clay loam or silty clay loam
Clay content: 30 to 38 percent
Rock fragments: 0 to 59 percent strongly cemented mudstone and sandstone gravel, 0 to 20 percent strongly cemented sandstone cobbles
Pararock fragments: 0 to 59 percent moderately cemented mudstone paragravel
Reaction: moderately acid

Some pedons have a BCt horizon
Hue: 10 YR or 2.5Y
Value: 5 to 7, 3 or 4 moist
Chroma: 2 to 4, dry or moist
Texture of fine earth: sandy clay loam, clay loam, or silty clay loam
Clay content: 27 to 38 percent
Rock fragments: 0 to 59 percent strongly cemented mudstone and sandstone gravel, 0 to 20 percent strongly cemented sandstone cobbles
Pararock fragments: 0 to 59 percent moderately cemented mudstone paragravel
Reaction: moderately acid

COMPETING SERIES: There are no other series in this family.

GEOGRAPHIC SETTING: Capetown soils are on linear to concave or slightly convex positions on backslopes and footslopes on mountains. Slopes are 5 to 30 percent. Elevations range from 10 to 855 meters. These soils formed in colluvium derived from sandstone and mudstone. The climate is humid with cool, foggy summers and cool, wet winters. Mean annual precipitation is 1140 to 2280 millimeters and the mean annual temperature is 10 to 12 degrees C. The frost-free period is about 240 to 330 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Caperidge (T) and Northbear (T) soils. Caperidge and Northbear soils do not have redoximorphic features within 150 centimeters. Caperidge soils contain more than 35 percent rock fragments and are found on convex to slightly concave positions on mountain slopes. Northbear soils are found on linear to concave or convex positions on mountain slopes.

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Moderately well drained; high or very high runoff; moderately high saturated hydraulic conductivity. A seasonal high water table occurs between 50 to 100 centimeters December through March.

USE AND VEGETATION: This soil is used for timber production, wildlife habitat, and watershed. Natural vegetation includes grand fir, Douglas-fir, tanoak, California laurel, red alder, poison oak, evergreen huckleberry, western swordfern, oceanspray, Douglas iris, and thimbleberry.

DISTRIBUTION AND EXTENT: Coastal Redwood Belt; MLRA 4B. The series is not extensive.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California

SERIES ESTABLISHED: Central Humboldt County Soil Survey, California 2016. The name is from the town of Capetown, CA.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
1. Mollic epipedon: The zone from 0 to 55 centimeters (A1, A2, and ABt horizons)
2. Argillic horizon: The zone from 33 to 200 centimeters (ABt, Bt1, Bt2, and BCt horizons)
3. Aquic feature: The zone from 80 to 200 centimeters (Bt2 and BCt horizons)
3. Particle-size control section: The zone from 33 to 83 centimeters averages 31 percent clay, 18 percent fine sand or coarser by weight, and 2 percent paragravels by volume (ABt, Bt1, and Bt2 horizons)

ADDITIONAL DATA:

Keys to Soil Taxonomy, 12th edition

NASIS User Pedon ID: 09CA600190

National Cooperative Soil Survey
U.S.A.