LOCATION TIMMONS CA

Established Series
Rev. ACF/SAA/JJJ/ET/JW
10/2016

TIMMONS SERIES

The Timmons series consists of very deep, well drained soils formed in marine deposits derived from mixed sources. Timmons soils are on nearly level to gently sloping, dissected marine terraces and have slopes 0 to 9 percent. The mean annual precipitation is 1500 millimeters (59 inches) and the mean annual temperature is about 12 degrees C (53 degrees F).

TAXONOMIC CLASS: Fine-loamy, mixed, superactive, mesic Typic Palehumults

TYPICAL PEDON: Timmons loam - on a nearly level, linear slope of 1 percent under pasture grasses and forbs, at 12 meters (38 feet) elevation. (Colors are for moist soil unless otherwise stated. When described September 19, 2007, the soil was slightly moist 0 to 30 centimeters and moist 30 to 152 centimeters).

Ap1--0 to 28 centimeters (0 to 11 inches); dark brown (7.5YR 3/2) loam, brown (7.5YR 4/3) dry; weak medium subangular blocky and moderate medium granular structure; soft, very friable, nonsticky and slightly plastic; many very fine and common fine roots throughout; common very fine and fine irregular and common very fine tubular pores; strongly acid (pH 5.2); clear smooth boundary.

Ap2--28 to 48 centimeters (11 to 19 inches); very dark brown (7.5YR 2/2) loam, brown (7.5YR 4/3) dry; moderate very fine and fine subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; common very fine and fine roots throughout; common very fine and fine irregular and common very fine tubular pores; strongly acid (pH 5.2); clear smooth boundary. (Combined thickness of A horizons is 25 to 70 centimeters)

AB--48 to 75 centimeters (19 to 30 inches); dark brown (7.5YR 3/4) loam, brown (7.5YR 4/4) dry; moderate fine subangular blocky structure; slightly hard, friable, slightly sticky and moderately plastic; common very fine and fine roots throughout; common very fine irregular and common very fine tubular pores; strongly acid (pH 5.2); clear smooth boundary. (0 to 40 centimeters thick)

Bt1--75 to 95 centimeters (30 to 37 inches); brown (7.5YR 4/4) clay loam, reddish yellow (7.5YR 6/6) dry; moderate fine and medium subangular blocky structure; moderately hard, firm, moderately sticky and moderately plastic; few fine roots throughout; common very fine irregular and common very fine tubular pores; few faint clay films on surfaces along pores; very strongly acid (pH 5.0); gradual smooth boundary.

Bt2--95 to 120 centimeters (37 to 47 inches); strong brown (7.5YR 4/6) clay loam, reddish yellow (7.5YR 6/6) dry; moderate fine and medium subangular blocky structure; slightly hard, friable, moderately sticky and moderately plastic; few fine roots throughout; common very fine tubular pores; few distinct and faint clay films on surfaces along pores; strongly acid (pH 5.2); gradual smooth boundary.

Bt3--120 to 152 centimeters (47 to 60 inches); strong brown (7.5YR 5/6) clay loam, reddish yellow (7.5YR 6/6) dry; weak medium subangular blocky structure; slightly hard, friable, moderately sticky and moderately plastic; common very fine tubular pores; few faint clay films on surfaces along pores; strongly acid (pH 5.2). (Combined thickness of the Bt horizons is 60 to 120 centimeters)

TYPE LOCATION: Del Norte County, California; located approximately 7 kilometers (4.3 miles) northeast of Crescent City, California; Section 34, T.17N. R.1W., WGS84 Decimal degrees 41.8603889 latitude and -124.1525833 longitude; HBLM, USGS Sisters Rocks Quadrangle; UTM Zone 10 402893mE 4630752mN; 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 soil moisture regime.

Soil temperature: The mean annual soil temperature at 50 centimeters (20 inches) is 12 to 14 degrees C (53 to 57 degrees F). The average summer soil temperature is about 18 degrees C and the average winter soil temperature is about 9 degrees C. The difference between average summer and winter soil temperatures is about 6 to 9 degrees C. The soils have a mesic temperature regime.

The umbric epipedon is 30 to 90 centimeters thick.

Particle-Size Control Section (weighted average):

Pararock Fragments: 0 to 5 percent gravels
Clay content: 25 to 33 percent

A or Ap horizon

Hue: 7.5YR or 10YR
Value: 2 through 3, or 4 or 5 dry
Chroma: 2 or 3, or 3 or 4 dry

Texture of fine earth: loam
Clay content: 18 to 27 percent
Rock fragments: 0 to 10 percent gravels
Reaction: very strongly to strongly acid

Bt horizon

Hue: 7.5YR or 10YR
Value: 4 or 5, or 5 through 7 dry
Chroma: 4 or 6 moist and dry

Texture of fine earth: sandy clay loam, or clay loam
Pararock fragments: 0 to 5 percent gravel
Clay content: 25 to 34 percent
Reaction: very strongly to strongly acid

COMPETING SERIES: There are no competing series at this time.

GEOGRAPHIC SETTING: Timmons soils are on nearly level to gently sloping, slightly dissected marine terraces and have slopes of 0 to 9 percent. Elevations are 0 to 183 meters (0 to 600 feet). These soils form in marine deposits derived from mixed sources. A strong marine influence limits the diurnal and annual range of temperature. The climate is humid with cool, foggy summers and cool, wet winters. The mean annual temperature is 11 to 13 degrees C (51 to 55 degrees F). The mean annual precipitation is 890 to 2285 millimeters (35 to 90 inches). The frost-free period is 275 to 325 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Lepoil soils. Lepoil soils occur under cool forested environments of Sitka spruce and redwood, where the difference between mean summer and mean winter soil temperatures is less than 6 degrees C.

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

USE AND VEGETATION: This soil is used predominantly for pasture, recreation and urban development. Vegetation includes California blackberry, common dandelion, white clover, sweet vernalgrass, brome, common velvetgrass, vernalgrass, blue grass, and other pasture grasses and forbs.

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, Humboldt County, California, 2012. Proposed July 1964.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
1. Umbric epipedon - the zone from 0 to 48 centimeters (Ap1 and Ap2 horizons).
2. Argillic horizon - the zone from 48 to 152 centimeters (AB, Bt1, Bt2 and Bt3 horizons).
3. Particle-size control section - the zone from 48 to 98 centimeters, averages 28 percent clay and 30 percent fine sand and coarser, by weight.(AB and Bt1 horizons)

Edit Log: Timmons was originally proposed in 1965 with well and moderately well drained Map Units. In 2009 Timmons was revisited and decision made to separate well and moderately well drained soils, as well as soils under forest canopy and isomesic from cleared or developed areas that are mesic. This resulted in four separate soil series. The typical pedon was changed in January of 2010 to reflect the well drained series concept on permanent pasture.

Soil classified using the 12th Edition of the Keys to Soil Taxonomy.
NASIS User Pedon ID 07CA605382

National Cooperative Soil Survey
U.S.A.