LOCATION TRAILHEAD CA
Established Series
Rev: JHP/JPS/ET
05/2016
TRAILHEAD SERIES
The Trailhead series consists of very deep, well drained soils formed in residuum and colluvium derived from schist and sandstone. Trailhead soils are on mountains and have slopes of 0 to 50 percent. The mean annual precipitation is about 2160 millimeters (85 inches) and the mean annual temperature is about 11 degrees C (52 degrees F).
TAXONOMIC CLASS: Fine, parasesquic, isomesic Typic Palehumults
TYPICAL PEDON: Trailhead clay loam - on a south-facing convex slope of 25 percent under redwood, Douglas fir, tanoak, western hemlock, huckleberry, Pacific rhododendron, and Oregon grape at 274 meters (900 feet) elevation. (Colors are for moist soil unless otherwise stated. When described June 20, l983, the soil was moist throughout.)
Oi--0 to 2 centimeters (0 to 1 inches); fresh and slightly decomposed conifer needles, tanoak leaves and twigs; about 25 percent cover of surface gravel; moderately acid (pH 6.0). (0 to 4 centimeters thick)
A--2 to 13 centimeters (1 to 5 inches); dark brown (7.5YR 3/3) clay loam, brown (7.5YR 4/4) dry; moderate medium, subangular blocky structure, parting to moderate fine subangular blocky; slightly hard, friable, slightly sticky and slightly plastic; common very fine, many fine, and common medium roots throughout; common very fine irregular and common very fine and fine tubular pores; common, fine, rounded, yellowish red (5YR 5/6) iron nodules; about 3 percent rounded to subangular gravel; moderately acid (pH 6.0); clear wavy boundary. (6 to 47 centimeters thick)
AB--13 to 30 centimeters (5 to 12 inches); reddish brown (5YR 4/4) clay loam, reddish brown (5YR 5/4) dry, moderate medium subangular blocky structure, parting to moderate fine subangular blocky; hard, friable, slightly sticky and moderately plastic; common fine and medium, and few coarse roots throughout; common very fine irregular and common very fine and fine tubular pores; common, fine, rounded yellowish red (5YR 5/6) iron nodules; about 2 percent gravel; moderately acid (pH 5.8); gradual wavy boundary. (0 to 38 centimeters thick)
BAt--30 to 68 centimeters (12 to 27 inches); yellowish red (5YR 4/6) clay loam, yellowish red (5YR 5/6) dry; weak coarse subangular blocky structure, parting to weak medium subangular blocky; slightly hard, firm, moderately sticky and moderately plastic; common fine, medium and coarse roots throughout; few very fine, fine and medium tubular pores; few faint to distinct clay films in pores and on faces of peds; less than 3 percent gravel; moderately acid (pH 5.6); diffuse smooth boundary. (0 to 53 centimeters thick)
Bt1--68 to 92 centimeters (27 to 36 inches); yellowish red (5YR 4/6) clay, yellowish red (5YR 5/6) dry; weak very coarse subangular blocky structure, parting to weak medium subangular blocky; hard, firm, moderately sticky and very plastic; common fine, medium and coarse roots throughout; few very fine and fine tubular pores; few distinct clay films in pores and on faces of peds; less than 3 percent gravel; moderately acid (pH 5.7); diffuse smooth boundary.
Bt2--92 to 167 centimeters (36 to 66 inches); red (2.5YR 4/6) clay, yellowish red (5YR 5/6) dry; weak very coarse subangular blocky structure; hard, firm, moderately sticky and very plastic; common fine and medium and few coarse roots throughout; few very fine and fine tubular pores; common distinct clay films in pores and few distinct clay films on faces of peds; less than 3 percent gravel; moderately acid (pH 5.7); diffuse smooth boundary.
Bt3--167 to 202 centimeters (66 to 80 inches); red (2.5YR 4/6) clay, yellowish red (5YR 5/6) dry; weak very coarse subangular blocky structure; hard, firm, moderately sticky and very plastic; few fine and medium roots throughout; few very fine and fine tubular pores; common distinct clay films in pores and on faces of peds; about 7 percent gravel; moderately acid (pH 5.6). (Combined thickness of Bt horizons is 65 to 150 centimeters)
TYPE LOCATION: Redwood National Park, Humboldt County, California; located 19 kilometers southeast of the town of Orick; 152 meters west-northwest of trailhead to Tall Trees Grove from C-Line Road; southeast quarter, southwest quarter, Section 31, T. 10 N., R. 2 E., WGS84 Decimal degrees latitude and -123.9959833 longitude; HBLM; USGS Bald Hills Quadrangle. UTM Zone 10 414809mE 4562447mN; NAD83
RANGE IN CHARACTERISTICS:
Soil Moisture: The soil is usually moist in all parts in the soil moisture control section in most years, but becomes nearly dry in the upper part from about September 15 to October 15 in most years. The soils have an Udic moisture regime.
Soil Temperature: The mean annual soil temperature is 10 to 13 degrees C (50 to 55 degrees F). The difference between mean summer and mean winter temperature is 2 to 4 degrees C.
Organic Matter: There is 12 to 25 kg per square meter of organic carbon to a depth of one meter.
CEC to clay ratio is 16 to 24 meq/100g in the major part of the argillic horizon.
Reaction is strongly or very strongly acid throughout. Base saturation is 5 to 35 percent between depths of 25 to 202 centimeters.
Surface fragments: 0 to 10 percent gravel
Particle-Size Control Section (weighted average):
Rock fragments: 0 to 15 percent gravel
Clay content: 40 to 60 percent clay
O horizon
Hue: 10YR.
Value: 2 through 6 dry and moist
Chroma: 1 through 4 dry and moist
Texture: slightly decomposed organic material
Wood fragments: 0 to 35 percent
Reaction: moderately to slightly acid
A horizon
Hue: 5YR or 7.5YR.
Value: 4 or 6 dry, 3 through 6 moist
Chroma: 3 or 4 dry, 2 through 4 moist
Texture of fine earth: silt loam, clay loam, or silty clay loam
Clay content: 27 to 35 percent
Rock fragments: 0 to 25 percent gravel
Bt horizon
Hue: 2.5YR or 5YR.
Value: 3 through 6 dry, 4 through 8 moist
Chroma: 3 through 8 dry, 6 or 8 moist
Texture of fine earth: silty clay loam, silty clay or clay
Clay content: 40 to 60 percent.
Rock fragments: 0 to 30 percent gravel and 0 to 5 percent cobbles
Paragravel: 0 to 15 percent
Some pedons have C horizons.
C horizon:
Hue: 2.5YR or 5YR
Value: 3 through 6 dry, 4 through 8 moist
Chroma: 3 through 8 dry, 6 or 8 moist
Texture of fine earth: silty clay loam, silty clay or clay
Clay content: 35 to 60 percent
Rock fragments: 35 to 50 percent gravel and 35 to 50 percent cobbles
Paragravel: 0 to 15 percent
COMPETING SERIES: This is the
Buzzini series. Buzzini soils have an umbric epipedon.
GEOGRAPHIC SETTING: Trailhead soils occur on broad ridges and upper slopes of mountains. Slopes are 0 to 50 percent. Elevations are 15 to 780 meters (50 to 2560 feet). The soils formed in residuum and colluvium derived from schist and sandstone. The climate is humid with cool foggy summers and cool moist winters. Coastal influence limits the annual and diurnal range in temperature. Mean annual precipitation ranges from 1780 to 2550 millimeters (70 to 100 inches). Mean January temperature is about 9 degrees C; mean July temperature is about 14 degrees C; and the mean annual temperature is 10 to 13 degrees C (50 to 55 degrees F). Frost-free season is 240 to 290 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Coppercreek and the
Fortyfour soils. Coppercreek soils are 10YR to 7.5YR throughout and are fine-loamy. Fortyfour soils are 50 to 100 centimeters (20 to 40 inches) deep to a paralithic contact. The Coppercreek soils are in broad hollows and on steeper slopes below the Trailhead soils. The Fortyfour soils are on convex areas below, and spur ridges above the Trailhead soils.
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Well drained; medium to very high runoff; moderately low to low saturated hydraulic conductivity.
USE AND VEGETATION: This soil has been used for commercial timber and is used for recreation, wildlife and watershed. Natural vegetation consists of redwood, Douglas-fir, western hemlock, tanoak, huckleberry, and Pacific rhododendron.
DISTRIBUTION AND EXTENT: California Coastal Redwood Belt; MLRA 4B. The series is not extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Humboldt Del Norte area, California 2007. Source of name is from the Tall Trees trailhead in Redwood National Park south of the town of Orick.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
1. Ochric epipedon - the zone from 0 to 30 centimeters (Oi, A, and AB horizon)2. Argillic horizon - the zone from 30 to 202 centimeters (BAt, Bt1, Bt2, & Bt3 horizons)
3. Ultisol feature - base saturation of 20 percent at the critical depth, 125 centimeters below the upper boundary of the argillic horizon
4. Humult feature - 22.7 kilograms per square meter of organic carbon to a depth of 1 meter
5. Palehumult features - Clay remains at least 92 percent of its maximum to a depth of 200 centimeters
6. Parasesquic mineralogy - There is 24 percent dithionite-extractable sesquioxides in the clay fraction of the particle-size control section
7. CEC to clay ratio is 16 to 24 meq/100g in the major part of the argillic horizon
8. Particle-size control section - the zone from 30 to 80 centimeters, averages 41 percent clay and 21 percent fine sand or coarser, by weight, and 4 percent rock fragments, by volume. (BAt, Bt1 horizons)
Other features - There is 91 percent resistant minerals in the very fine sand fraction. The very fine sand and silt fractions are mostly quartz, although coarser sand and gravel fractions are predominantly schist fragments. Vermiculite, kaolinite, and chlorite are identifiable clay minerals by x-ray analysis. Although vermiculite is a major clay mineral, the CEC is kept low by the combined influence of ferric iron, gibbsite, and kaolinite.
ADDITIONAL DATA: The Trailhead type pedon is field sample number S83-CA-12-01, analyzed at Oregon State University and at NSSL. Backup samples S83-CA-12-02 and S83-CA-12-03 were analyzed for mineralogy class at NSSL. University of California samples 60-CA-12-17X and 60-CA-12-18X was collected for the Soil-Vegetation Survey in Redwood National Park.
NASIS User Pedon ID: 82CA605REDW001
Soil classified using the 12th Edition of the Keys to Soil Taxonomy.
National Cooperative Soil Survey
U.S.A.