LOCATION TILLAS                  CA

Established Series
REV: ACF/JPS/ET
10/2016

TILLAS SERIES

The Tillas series consists of very deep, well drained soils that formed in alluvium derived from mixed sources. Tillas soils are on alluvial fans. Slopes are 0 to 9 percent. The mean annual precipitation is about 2030 millimeters (80 inches) and mean annual temperature is about 12 degrees C (54 degrees F).

TAXONOMIC CLASS: Fine-loamy, mixed, superactive, mesic Cumulic Humudepts

TYPICAL PEDON: Tillas gravelly clay loam - on a south facing, linear to slightly convex slope of 2 percent under orchard grass, clover and other grasses at 13 meters (40 feet) elevation. (Colors are for moist soil unless otherwise stated. When described May 9, 2007, the soil was slightly moist to 110 centimeters and moist to 200 centimeters).

Ap1--0 to 35 centimeters (0 to 14 inches); very dark grayish brown (2.5Y 3/2) gravelly clay loam, grayish brown (2.5Y 5/2) dry; weak very fine and medium subangular blocky structure; hard, firm, moderately sticky and moderately plastic; many very fine and common fine roots; common very fine and fine tubular and very fine irregular pores; 20 percent gravel; strongly acid (pH 5.2); clear smooth boundary.

Ap2--35 to 62 centimeters (14 to 24 inches); dark olive brown (2.5Y 3/3) gravelly clay loam, olive brown (2.5Y 4/3) dry; moderate medium subangular blocky structure; slightly hard, friable, moderately sticky and moderately plastic; many very fine and common fine roots; common very and fine tubular pores; 15 percent gravel; strongly acid (pH 5.5); clear wavy boundary.

Ap3--62 to 93 centimeters (24 to 37 inches); very dark grayish brown (2.5Y 3/2) clay loam, olive brown (2.5Y 4/3) dry; weak fine and medium subangular blocky structure; slightly hard, friable, moderately sticky and moderately plastic; common very fine roots; common very and fine tubular pores; 10 percent gravel; very strongly acid (pH 5.0); clear smooth boundary. (Combined thickness of the Ap horizons is 30 to 100 centimeters)

A/B--93 to 112 centimeters (37 to 44 inches); 75 percent dark olive brown (2.5Y 3/3) and 25 percent yellowish brown clay loam, light olive brown (2.5Y 5/3) and very pale brown 10YR 7/4 dry; weak fine and medium subangular blocky structure; slightly hard, friable, moderately sticky and moderately plastic; common very fine roots; common very fine irregular and very fine tubular pores; 10 percent gravel; very strongly acid (pH 5.0); abrupt wavy boundary. (0 to 30 centimeters thick)

Bw--112 to 125 centimeters (44 to 49 inches); light olive brown (2.5Y 5/4) clay loam, pale yellow (2.5Y 7/4) dry; weak fine and medium subangular blocky structure; slightly hard, friable, slightly sticky and moderately plastic; common fine and medium strong brown (7.5YR 5/8) masses of iron accumulation and few fine and medium iron depletions in matrix; common very fine roots; very few very fine irregular pores; 8 percent gravel; very strongly acid (pH 4.8); clear wavy boundary. (0 to 100 centimeters thick)

Bt1--125 to 154 centimeters (49 to 61 inches); light olive brown (2.5Y 5/4) gravelly clay loam, pale yellow (2.5Y 7/4) dry; weak fine and medium subangular blocky structure; slightly hard, friable, moderately sticky and moderately plastic; few very fine roots; few very fine tubular and irregular pores; few faint clay films on ped faces and on surfaces along pores; 20 percent gravel and 5 percent paragravel; very strongly acid (pH 4.8); clear wavy.

Bt2--154 to 200 centimeters (61 to 79 inches); light olive brown (2.5Y 5/4) gravelly clay loam, pale yellow (2.5Y 7/4); weak medium subangular blocky structure; slightly hard, friable, moderately sticky and moderately plastic; very few very fine roots; very few very fine tubular and irregular pores; faint clay films on ped faces and on surfaces along pores; 25 percent gravel and 2 percent paragravel; very strongly acid (pH 4.8). (Combined thickness of the Bt horizons is 0 to 100 centimeters)

TYPE LOCATION: Del Norte County, California; USGS Smith River Quadrangle; WGS84 Decimal degrees 41.9313889 latitude and -124.1588889 longitude, UTM Zone 10 403930mE 4642795mN; NAD83.

RANGE IN CHARACTERISTICS: The mean annual soil temperature is 12 to 15 degrees C (54 to 59 degrees F). The difference between the mean winter and mean summer soil temperatures varies from 6 to 9 degrees C. The soils are usually moist and are dry for less than 45 consecutive days in all parts between depths of 10 to 30 centimeters (4 and 12 inches) in the four months following the summer solstice.

Umbric epipedon is 30 to 100 centimeters (12 to 39 inches) thick.

The particle-size control section (weighted average)

Rock fragments: 0 to 25 percent
Clay content: 30 to 35 percent

A horizon

Hue: 10YR or 2.5Y.
Value: 4 or 5 dry, 2 or 3 moist.
Chroma: 2 or 3 dry and 1 or 2 moist.

Texture of fine earth: clay loam.
Rock fragments: 0 to 30 percent gravel.
Clay content: 27 to 33 percent.
Reaction: very strongly or strongly acid.

Bw horizon

Hue: 10YR or 2.5Y.
Value: 5 through 7 dry, 3 through 6 moist.
Chroma: 3 through 6 dry and 2 through 6 moist.

Texture of fine earth: clay loam.
Rock fragments: 0 to 35 percent gravel.
Clay content: 27 to 40 percent.
Reaction: very strongly or strongly acid.

Bt horizon

Hue: 10YR or 2.5Y.
Value: 5 through 7 dry, 3 through 6 moist.
Chroma: 3 through 5 dry and 2 through 6 moist.

Texture of fine earth: clay loam.
Rock fragments: 0 to 35 percent gravel.
Para rock fragments: 0 to 10 percent paragravel.
Clay content: 27 to 40 percent.
Reaction: very strongly or strongly acid.

Some pedons have C horizons.

C horizon

Hue: 10YR or 2.5Y.
Value: 6 or 7 dry, 3 through 5 moist.
Chroma: 3 or 4 dry and 2 through 4 moist.

Texture of fine earth: clay loam.
Rock fragments: 20 to 50 percent gravel.
Clay content: 27 to 40 percent.
Reaction: very strongly or strongly acid.

COMPETING SERIES: These are the Transylvania and Tsunami series. Transylvania soils have redoximorphic features and matrix color of 2 or less at a depth of 100 to 150 centimeters. Tsunami soils lack clay films throughout.

GEOGRAPHIC SETTING: Tillas soils are on alluvial fans. Slopes are 0 to 9 percent. The soils formed in alluvium derived from mixed sources. Elevations are 4 to 82 meters (13 to 269 feet). The climate is humid, characterized by warm wet winters and warm moist summers with fog. A strong marine influence limits the diurnal and annual range of temperature. The mean annual temperature is 11 to 14 degrees C (52 to 57 degrees F). The mean annual precipitation is 1778 to 2286 millimeters (70 to 90 inches). The frost-free period is 275 to 325 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Carlotta, Ferndale, Hookton, and Weott soils. Carlotta soils are moderately well drained and have redoximorphic features from 50 to 100 centimeters deep. Ferndale soils do not have cambic horizons and are fine-silty. Hookton soils are somewhat poorly drained and have redoximorphic features from 25 to 100 centimeters deep. Weott soils are poorly drained and have redoximorphic features from 6 to 10 centimeters deep. Carlotta soils are found on fluvial terraces. Hookton soils are found on wetter areas of alluvial fans. Ferndale and Weott soils are on floodplains.

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

USE AND VEGETATION: The soils are used mainly for bulb production and pasture. Native vegetation is Douglas fir, redwood, grand fir, California laurel, red alder, willow, bigleaf maple, and salmonberry.

DISTRIBUTION AND EXTENT: Coastal Redwood Belts; MLRA 4B. The series is of small extent.

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

SERIES PROPOSED: Del Norte County, California, 2013. The source of the name is from Tillas Slough.

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

1. Umbric epipedon - the zone from 0 to 93 centimeters. (Ap1,Ap2,and Ap3 horizons)
2. Cambic horizon - the zone from 112 to 200 centimeters. (Bw, Bt1, Bt2 horizons)
3. Particle-size control section - the zone from 25 to 100 centimeters, averages 33 percent clay, 23 percent fine sand and coarser, by weight,and 10 percent rock fragments, by volume. (Ap1, Ap2, Ap3, and Bw horizons)

Tillas soils do not have a diagnostic argillic horizon. Clay films are present in most surface horizons but lack a clay increase in the upper subsurface due to agricultural related mixing of the upper 100 centimeters of the soil.

Under native forest vegetation this soil has an isomesic soil temperature regime.

ADDITIONAL DATA:

NSSL, Lincoln Lab sample 08N0240

NASIS User Pedon ID 07-CA605-175

Soil classified using the 12th Edition of the Keys to Soil Taxonomy. In 2012 the classification was changed from Fluventic Humic Dystrudepts to Cumulic Humudepts to reflect the changes in Taxonomy and to better reflect lab data.

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National Cooperative Soil Survey
U.S.A.