LOCATION FLINTROCK               CA

Established Series
Rev: ACF/JPS/ET
01/2013

FLINTROCK SERIES

The Flintrock series consists of very deep, well drained soils that formed in debris flow colluvium derived from sandstone and mudstone. Flintrock soils are on steep and very steep hill slopes and have slopes of 15 to 75 percent. The mean annual precipitation is about 1780 millimeters (70 inches) and the mean annual temperature is about 11 degrees C (52 degrees F).

TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, isomesic Pachic Hapludolls

TYPICAL PEDON: Flintrock very gravelly clay loam - on a uniform west-facing slope of 65 percent under prostrate Sitka spruce, cow parsnip, brackenfern, wild cucumber, fireweed, foxglove and ripgut brome at 120 feet (37 meters) elevation. (Colors are for moist soil unless otherwise stated. When described May 31, 2005, the soil was moist throughout).

A--0 to 25 centimeters (0 to 10 inches); very dark grayish brown (10YR 3/2) very gravelly clay loam, brown (10YR 4/3) dry; moderate very fine and fine subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; common very fine, fine and medium and few coarse roots; common very fine and fine tubular and common very fine, fine, and medium irregular tubular pores; 35 percent gravel; slightly acid (pH 6.2); clear wavy boundary. (10 to 40 centimeters (4 to 16 inches) thick)

Bw1--25 to 47 centimeters (10 to 18 inches); very dark grayish brown (2.5Y 3/2) very gravelly clay loam, light olive brown (2.5Y 5/3) dry; moderate very fine and fine subangular blocky structure; slightly hard, friable, moderately sticky and moderately plastic; common very fine, fine and medium roots; common very fine and fine tubular and common very fine, fine, and medium irregular pores; 55 percent gravel, 2 percent cobbles and 10 percent stones; slightly acid (pH 6.2); clear wavy boundary.

Bw2--47 to 78 centimeters (18 to 31 inches); dark olive gray (5Y 3/2) extremely gravelly clay loam, olive gray (5Y 5/2) dry; weak fine and medium subangular blocky structure; moderately hard, firm, moderately sticky and moderately plastic; common very fine, fine, medium and coarse and very coarse roots; common very fine and fine tubular and common very fine, fine, and medium irregular pores; 60 percent gravel and 1 percent cobbles; moderately acid (pH 6.0); clear wavy boundary. (Combined thickness of the Bw horizons is 25 to 105 centimeters (10 to 41 inches) thick)

BC--78 to 97 centimeters (31 to 38 inches); very dark gray (5Y 3/1) very gravelly clay loam, gray (5Y 5/1) dry; weak medium subangular structure; moderately hard, firm, moderately sticky and moderately plastic; very few very fine and moderately few fine and common very coarse roots; common very fine and fine tubular and very fine and fine irregular pores; 55 percent gravel; moderately acid (pH 6.0); clear wavy boundary. (0 to 25 centimeters (0 to 10 inches) thick)

C1--97 to 118 centimeters (38 to 46 inches); very dark gray (5Y 3/1) extremely gravelly clay loam, gray (5Y 5/1) dry; massive; moderately hard, firm, moderately sticky and moderately plastic; very few very fine and common very coarse roots; common very fine, fine irregular pores; 65 percent gravel; slightly acid (pH 6.5); clear wavy boundary.

C2--118 to 160 centimeters (46 to 63 inches); black (5Y 2.5/1) extremely gravelly clay loam, dark gray (5Y 4/1) dry; massive; moderately hard, firm, moderately sticky and moderately plastic; very few very fine roots; common very fine, fine irregular pores; 70 percent gravel and 2 percent cobbles; slightly acid (pH 6.5); clear wavy boundary. (Combined thickness of the C horizons is 10 to 80 centimeters (4 to 32 inches))

TYPE LOCATION: Redwood National Park, Del Norte County, California; located approximately 15 meters (50 feet) south of High Bluffs coast access trail; section 17, T. 13 N., R. 1 E., 41 degrees, 30 minutes, 45.7 seconds north latitude and 124 degrees, 4 minutes, 49.6 seconds west longitude; HBLM, USGS Requa Quadrangle; UTM Zone 10 409841mE 4596236mN; 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 dry in the upper part for a time less than 30 days cumulative from about September 15 to October 15. 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.

Reaction is slightly to moderately acid and base saturation is more than 50 percent throughout.

Surface fragments: 0 to 30 percent gravel and 0 to 10 percent cobble

Particle-Size Control Section (weighted average):
Rock fragments: 35 to 60 percent gravel, 0 to 10 percent cobbles, and 0 to 10 percent stone.
Clay content: 27 to 35 percent clay.

A horizon

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

Texture of fine earth: clay loam.
Rock fragments: 35 to 50 percent gravel and 0 to 7 percent cobbles.
Clay content: 27 to 32 percent.

Bw horizon

Hue: 10YR, 2.5Y, 5Y, or N.
Value: 4 through 6 dry, 3 through 6 moist.
Chroma: / through 3 dry, / through 2 moist.

Texture of fine earth: clay loam.
Rock fragments: 35 to 60 percent gravel, 0 to 10 percent cobbles, and 0 to 10 percent stones.
Clay content: 27 to 35 percent.

C horizon

Hue: 5Y or N.
Value: 4 through 6 dry, 2.5 through 4 moist.
Chroma: / or 1 dry and moist.

Texture of fine earth: clay loam.
Rock fragments: 20 to 70 percent gravel, 0 to 50 percent cobbles.
Clay content: 27 to 40 percent.

COMPETING SERIES: At this time there are no other series in this family.

GEOGRAPHIC SETTING: Flintrock soils are on unstable lower hill slopes adjacent to the ocean. Slopes are 15 to 75 percent. Elevations are 0 to 213 meters (0 to 695 feet). The soils formed in debris flow colluvium from sandstone and mudstone. The climate is humid with cool, foggy summers and cool, rainy winters. Mean annual precipitation is 1520 to 2030 millimeters (60 to 80 inches). Mean January temperature is about 8 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 about 300 to 365 days.

GEOGRAPHICALLY ASSOCIATED SOILS: This is the Highprairie soils. Highprairie soils are fine-loamy; they have less than 35 percent rock in the particle size control section. Highprairie soils are above Flintrock soils on gentler, more stable slopes in linear to concave positions.

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Well drained; high to very high runoff; moderate saturated hydraulic conductivity.

USE AND VEGETATION: This soil has been used for wildlife and watershed. Natural vegetation consists of prostrate Sitka spruce, cow parsnip, brackenfern, wild cucumber, fireweed, foxglove and ripgut brome.

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 Flint rock head, an irregularity of land jutting out from the coast into the Pacific Ocean south of the Klamath River mouth.

REMARKS: Diagnostic horizons and features recognized in this pedon are:

1. Mollic epipedon - the zone from 0 to 97 centimeters (A and B horizons)
2. Particle-size control section - the zone from 25 to 100 centimeters, averages 33 percent clay, by weight, and 53 percent rock fragments, by volume.

Additional Data

Nasis User Pedon ID: 05CA605REDW061

Classified using the 11th Edition of the Keys to Soil Taxonomy. 10th Edition classification was loamy-skeletal, mixed, superactive, isomesic Typic Hapludolls.

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National Cooperative Soil Survey
U.S.A.