LOCATION TRIBOARD CA

Established Series
Rev. BAL/JPS/ET/SAA
05/2016

TRIBOARD SERIES

The Triboard series consists of very deep, moderately well drained soils formed in residuum and colluvium derived from metasedimentary rocks. These soils are on mountains and have slopes of 30 to 50 percent. Mean annual precipitation is 2032 millimeters (80 inches) and the mean annual temperature is 7 degrees C (44 degrees F).

TAXONOMIC CLASS: Fine, mixed, superactive, frigid Ultic Palexeralfs

TYPICAL PEDON: Triboard very gravelly loam - under a stand of white fir, grand fir, Douglas-fir, and snowberry. When described on September 15, 2004, the soil was dry throughout. (Colors are for dry soil unless otherwise stated).

Oi--0 to 3 centimeters (0 to 1 inches); slightly decomposed plant material; abrupt smooth boundary. (0 to 15 centimeters thick)

A--3 to 10 centimeters (1 to 4 inches); olive brown (2.5Y 4/3) very gravelly loam, very dark gray (10YR 3/1) moist; weak fine and medium subangular blocky structure; soft, very friable, nonsticky and nonplastic; many very fine and fine roots; many very fine interstitial, and many very fine tubular pores; 40 percent gravel, 3 percent cobbles; moderately acid (pH 5.6); abrupt smooth boundary. (6 to 15 centimeters thick)

Bt1--10 to 16 centimeters (4 to 6 inches); olive brown (2.5Y 4/4) gravelly silty clay loam, very dark grayish brown (2.5Y 3/2) moist; weak fine and medium subangular blocky structure; soft, friable, moderately sticky and moderately plastic; many very fine and fine roots; many very fine and fine tubular pores; common faint clay films on all faces of peds; 30 percent gravel; moderately acid (pH 5.6); clear smooth boundary.

Bt2--16 to 36 centimeters (6 to 14 inches); light olive brown (2.5Y 5/3) gravelly silty clay, very dark grayish brown (2.5Y 3/2) moist; moderate fine and medium subangular blocky structure; hard, firm, moderately sticky and moderately plastic; many very fine and fine roots; many fine tubular pores; common faint clay films on all faces of peds; 20 percent gravel; moderately acid (pH 5.8); clear wavy boundary.

Bt3--36 to 57 centimeters (14 to 22 inches); grayish brown (2.5Y 5/2) gravelly silty clay, very dark grayish brown (2.5Y 3/2) moist; weak fine and medium subangular blocky structure; hard, firm, very sticky and very plastic; many medium and coarse roots; many fine tubular pores; common distinct clay films on all faces of peds; 25 percent gravel, 20 percent paragravel, 5 percent cobbles; slightly acid (pH 6.4); clear wavy boundary.

Bt4--57 to 85 centimeters (22 to 34 inches); gray (2.5Y 5/1) gravelly clay, very dark grayish brown (2.5Y 3/2) moist; strong fine and medium subangular blocky structure; very hard, very firm, very sticky and very plastic; many medium and common coarse roots; common fine tubular pores; many distinct clay films on all faces of peds; 25 percent gravel, 20 percent paragravel; neutral (pH 7.1); gradual wavy boundary. (Combined thickness of Bt horizons is 60 to 100 centimeters)

BCt--85 to 158 centimeters (34 to 62 inches); dark grayish brown (2.5Y 4/2) gravelly silty clay, very dark gray (2.5Y 3/1) moist; 60 percent strong medium subangular blocky structure and 40 percent massive rock structure; extremely hard, extremely firm, very sticky and very plastic; common coarse roots; common coarse tubular pores; many distinct clay films on all faces of peds; 10 percent fine very weakly cemented iron-manganese masses; 25 percent gravel, 5 percent cobbles; neutral (pH 7.2). (50 to 80 centimeters thick)

TYPE LOCATION: Humboldt County, California; USGS Board Camp Mountain, topographic quadrangle; WGS84 Decimal degrees 40.7055278 latitude and -123.7238889 longitude; UTM 438840 meters E, 4506329 meters N, zone 10, NAD 83.

RANGE IN CHARACTERISTICS:

Soil moisture: The soil moisture control section is dry from July 1st to October 15th and moist in all parts from November 15 to June 1st. This soil has a xeric moisture regime.

Soil temperature: The mean annual soil temperature is 5 to 7 degrees C (41 to 45 degree F). The difference between the mean summer and mean winter temperature is greater 6 degrees C. This soil has a mesic soil temperature regime.

Base saturation is greater than 35 percent (by sum of cations) 125 centimeters below the top of the argillic horizon and is less than 75 percent throughout.

Depth to redoximorphic features: 70 to 100 centimeters (28 to 39 inches)

Surface Fragments: 0 to 5 percent gravel

Particle Size Control Section (weighted average):

Clay: 35 to 50 percent.
Rock fragments: 5 to 35 percent gravel.

A Horizon

Hue: 10YR or 2.5Y
Value: 3 or 4 dry; 2 or 3 moist.
Chroma: 3 or 4 dry, 1 through 3 moist.

Texture of fine earth fraction: loam
Clay content: 12 to 25 percent
Rock fragments: 35 to 55 percent gravel and 0 to 5 percent cobbles
Soil Reaction: moderately acid to neutral

Bt Horizons
Hue: 10YR or 2.5Y
Value: 3 through 5 dry, 3 or 4 moist.
Chroma: 1 through 4, dry or moist.

Texture of fine earth fraction: silty clay loam, clay, silty clay,
Clay content: 30 to 50 percent
Rock fragments: 5 to 35 percent gravel and 0 to 5 percent cobbles
Pararock fragments: 5 to 30 percent paragravel
Soil Reaction: moderately acid to neutral

Some pedons have C horizons

BCt Horizons

Hue: 10YR or 2.5Y
Value: 3 through 5 dry, 3 or 4 moist.
Chroma: 1 through 4, dry or moist.

Texture of fine earth fraction: clay, or silty clay
Clay content: 40 to 55 percent
Rock fragments: 5 to 30 percent gravel and 0 to 5 percent cobbles
Soil Reaction: slightly acid to neutral

COMPETING SERIES: These are the Flarm and Mal soils. Flarm soils have redoximorphic features between 25 and 50 centimeters and are somewhat poorly drained. Mal soils are derived from tuffaceous and basaltic materials.

GEOGRAPHIC SETTING: These soils occur on mountain slopes with slopes of 30 to 50 percent. They are in concave land positions at elevations of 1090 to 1486 meters (3576 to 4875 feet). These soils formed in colluvium and residuum from metasedimentary rock. The climate is subhumid with warm dry summers and cold moist winters. The mean annual precipitation is 2032 to 2794 millimeters (80 to 110 inches). Mean January temperature is about 3 degrees C (37 degrees F); mean July temperature is about 13 degrees C (56 degrees F); and the mean annual temperature is 5 to 8 degrees C (41 to 47 degrees F). The frost free period is about 75 to 150 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Boardcamp and Smokehouse soils. The Boardcamp soils are fine-loamy with less than 35 percent clay in the particle size control section and are found in areas of sandstone and mudstone. Smokehouse soils are loamy-skeletal with greater than 35 percent rock fragments in the particle size control section and are found in areas of sandstone lithology.

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: moderately well drained; very high runoff; slow saturated hydraulic conductivity.

USE AND VEGETATION: Used for timber production, wildlife habitat and watershed. Native vegetation is white fir, grand fir, incense cedar and Douglas-fir with an understory of snowberry, whitethorn ceanothus and bracken fern.

DISTRIBUTION AND EXTENT: Siskiyou-Trinity Area, MLRA 5. These soils are of small extent.

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

SERIES ESTABLISHED: Humboldt County, California, 2012. Proposed 2005.

REMARKS: Diagnostic horizons and features include:

1. Ochric horizon - The zone from 0 to 10 centimeters (Oi and A horizons)
2. Argillic horizon - The zone from 10 to 158 centimeters (Bt1, Bt2, Bt3, Bt4 and BCt horizons)
3. Particle-size control section - the zone from 10 to 60 centimeters, averages 41 percent clay and 5 percent fine sand or coarser, by weight, and 26 percent rock fragments, by volume. (Bt1, Bt2, Bt3, Bt4 horizons)

ADDITIONAL DATA:

User Pedon ID: 04CA023605077

Soil classified using the 12th Edition of the Keys to Soil Taxonomy. 10th Edition classification was Fine, mixed, superactive, frigid Mollic Palexeralfs.

National Cooperative Soil Survey
U.S.A.