LOCATION THUMS                   CA

Established Series
Rev. MEB/KP/RLR
03/2017

THUMS SERIES

The Thums series consists of very deep, well drained soils that formed in uplifted alluvium from mixed rock sources and have a thin mantle of human transported material at the surface. Thums soils are on terraces and fan remnants. Slopes range from 0 to 12 percent. The mean annual precipitation is about 331 mm and the mean annual temperature is about 18 degrees C.

TAXONOMIC CLASS: Fine, smectitic, thermic Calcic Pachic Argixerolls

TYPICAL PEDON: Thums, at an elevation of 15 meters. (Colors are for dry soil unless otherwise noted).

^Au--0 to 6 centimeters; dark grayish brown (10YR 4/2) clay loam, very dark brown (10YR 2/2), moist; many medium distinct brown (10YR 4/3) mottles; strong coarse granular structure; slightly hard, friable, moderately sticky, moderately plastic; many very fine roots and many fine roots; few fine and medium artifacts; neutral (pH 7.0); abrupt smooth boundary. (5 to 58 cm thick)

^Cu--6 to 26 centimeters; brown (10YR 4/3) clay loam, very dark grayish brown (10YR 3/2), moist; many medium distinct brown (10YR 4/3) mottles; strong medium subangular blocky structure; very hard, friable, very sticky, very plastic; common coarse roots and common medium roots; few fine and medium artifacts; common discontinuous clay films; finely disseminated carbonates, common fine distinct irregular carbonate masses in matrix; slightly effervescent; slightly alkaline (pH 7.4); soil structure, carbonates, and clay films are remnant from the source material; clear wavy boundary. (0 to 45 cm thick)

2Btk1--26 to 95 centimeters; brown (10YR 4/3) clay, very dark grayish brown (10YR 3/2), moist; moderate medium subangular blocky structure; very hard, friable, very sticky, very plastic; common fine roots; many distinct clay films on ped faces; common medium carbonate masses in matrix; slightly effervescent; moderately alkaline (pH 8.2); clear broken boundary.

2Btk2--95 to 115 centimeters; brownish yellow (10YR 6/6) silty clay, dark yellowish brown (10YR 4/4), moist; moderately hard, firm, moderately sticky, moderately plastic; many distinct clay films on ped faces; finely disseminated carbonates, common medium carbonate masses in matrix; strongly effervescent; moderately alkaline (pH 8.0); gradual wavy boundary.

2Btn--115 to 170 centimeters; brownish yellow (10YR 6/6) silty clay loam, dark yellowish brown (10YR 4/4), moist; slightly hard, firm, moderately sticky, moderately plastic; many distinct clay films on ped faces; common very fine distinct salt masses; slightly alkaline (pH 7.6). (Combined thickness of all Bt horizons is 110 to 185 cm)

TYPE LOCATION: Los Angeles County, California, Los Altos Park in Long Beach; 33 degrees, 47 minutes, 1 seconds North latitude and 118 degrees, 7 minutes, 54 seconds West longitude, NAD83 - U.S.G.S Quad: Long Beach (digital), California.

RANGE IN CHARACTERISTICS:
Soil moisture: The soil becomes moist below a depth of about 30 cm some time from October to December and remains moist in some part between depths of about 30 to 90 cm until April or May. It is dry remainder of the year, except in areas with continuous irrigation.
Soil temperature: 17 to 20 degrees C. The soil temperature usually does not go below 8 degrees C.

Rock fragments: 0 to 5 percent by volume.
Calcium carbonate equivalent: 1 to 10 percent.
Reaction: neutral to moderately alkaline and has finely disseminated and/or soft masses of calcium carbonate.
Depth to top of argillic: 15 to 45 centimeters from the surface.
Clay content: averages 35 to 48 percent clay in the particle size control section.

^A(u), A horizon:
Dry color: hue of 10YR, value of 4 or 5, chroma of 2 or 3
Moist color: hue of 10YR, value of 2 or 3, chroma of 1 to 3
Texture: Clay loam, loam or sandy loam
Clay content: 14 to 35 percent
Rock fragments: 0 to 5 percent gravel
Artifacts: 0 to 5 percent innocuous trash such plastic, brick and glass

^C(u) horizon:
Dry color: hue of 10YR, value of 3 to 6, chroma of 2 to 4
Moist color: 10YR, value of 2 to 4, chroma of 2 or 3
Texture: clay loam, loam, silty clay loam, sandy loam
Clay content:
Rock fragments: 0 to 15 percent from off-site sources
Artifacts: 0 to 10 percent innocuous trash such as plastic, brick and glass

2Bt, (2)Btk, 2Btn horizons:
Dry Color: hue of 10YR or 2.5Y, value of 4 to 6, chroma of 2 to 4
Moist color: hue of 10YR or 2.5Y, value of 3 to 5, chroma of 2 to 6
Texture: Clay loam and clay in the upper part and silty clay loam, silty clay, clay loam, or loam in the lower part
Clay content: 30 to 48 percent in the upper part and 18 to 38 percent in the lower part
Sodicity: SAR of 3 to 10 in the upper part and 10 to 25 in the lower part. Some pedons have salt accumulations in the lower Bt.

COMPETING SERIES: These are the Damluis and Delvar soils.
Damluis series - have a mean annual precipitation of 305 mm or less and have a frost free season that is less than 300 days.
Delvar series - have mean annual precipitation of 254 mm and are formed in alluvium weathered from granitic and meta-sedimentary parent materials.

GEOGRAPHIC SETTING:
Landscape: coastal plain, alluvial plain.
Landform: terraces, uplifted alluvium, remnant fans, and uplifted estuarine deposits.
Slopes: 0 to 12 percent.
Parent material: discontinuous human-transported materials overlying alluvium from mixed rock sources.
Elevation: 1 to 175 meters.
Mean annual precipitation: 280 to 480 mm.
Mean annual temperature: 16 to 19 degrees C.
Frost free season: 300 to 365 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Azuvina, Ballona, Botella, Centinela, Pierview, Rincon and Windfetch soils.
Azuvina soils: have less than 35 percent clay and have a mollic epipedon that is less than 50 cm thick on fan remnants.
Ballona soils: do not have a clay increase and are on fan aprons, floodplains, and remnant stream channels.
Botella soils: have less than 35 percent clay and are formed in alluvium weathered from granitic sources.
Centinela soils: have a linear extensibility greater than 6 and have slickensides in the profile.
Pierview soils: have less than 35 percent clay, an argillic horizons that extends below a depth of 150 cm and are on fan remnants.
Rincon soils: have an ochric epipedon and have a frost free season of 200 to 300 days on similar landscape positions.
Windfetch soil: have less than 35 percent clay and are on similar landscape positions.

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Well drained; moderate and high runoff; very slow and slow permeability. Water occasionally ponds up to 1 inch, above the surface for very brief duration from February through April.

USE AND VEGETATION: This soil is used for in urban areas for residential lands and parks. Vegetation is grass and ornamental plants.

DISTRIBUTION AND EXTENT: Coastal plains and valley of southern California in MLRA 19 - Southern California Coastal Plain. These soils are not extensive.

SOIL SURVEY REGIONAL OFFICE (SSRO) RESPONSIBLE: Davis, California

SERIES PROPOSED: Long Beach, Los Angeles County, California 2009.

REMARKS: Source of name from the acronym named after the group of companies who bought the right to develop the tidelands extension of California's largest oil field in 1965; Texaco Inc., Humble Oil & Refining Co., Union Oil Co., Mobil Oil Co. and Shell Oil Co..

Diagnostic horizons and features recognized in this pedon are:
Mollic Epipedon - the zone from a depth of 0 to 95 cm
Human-transported materials - the zone from a depth of 0 to 26 cm
Artifacts - the zone from a depth of 6 to 26 cm
Argillic horizon - the zone from a depth of 26 to 170 cm
Secondary Carbonates - the zone from a depth of 6 to 115 cm
Particle size control section - the zone from a depth of 26 to 76 cm

Human-transported materials at the surface are not a series requirement, are typically less than 50 cm thick and do not significantly impact interpretations. Soils with natural soil at the surface are included in this concept.

The argillic horizon can sometimes begin directly under HTM with or without a contrasting particle size.

ADDITIONAL DATA:

NASIS User Pedon ID: 2009CA696039
Classified using the Twelfth Edition Keys to Soil Taxonomy (2014)

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National Cooperative Soil Survey
U.S.A.