LOCATION RACAS                   CO

Established Series
PRR-KLS-EED
03/2026

RACAS SERIES

Depth class: Very deep
Drainage class: Well drained
Saturated hydraulic conductivity: Moderately low (0.04 to 0.36 cm/hr)
Parent material: Thick clayey human-transported material over loess or alluvium derived from loess
Geomorphic location: Fills and other leveled areas on loess-mantled plains and on floodways within loess-mantled plains
Slope range: 0 to 10 percent
Mean annual temperature: 11 degrees C
Mean annual precipitation: 405 millimeters

TAXONOMIC CLASS: Fine, spolic, smectitic, calcareous, mesic Torrertic Ustorthents

TYPICAL PEDON: Racas clay loam, 5 percent slope on a filled plain under cultivated grass in a park, at an elevation of 1,618 meters. (Colors are for dry soil unless otherwise noted.)

^Au--0 to 8 centimeters; pale brown (10YR 6/3) clay loam, brown (10YR 4/3) moist; moderate fine granular structure; moderately hard, firm, moderately sticky, moderately plastic; finely disseminated free carbonates throughout the matrix; 5 percent gravel; 3 percent artifacts of concrete and asphalt; strongly effervescent, slightly alkaline (pH 7.4); clear smooth boundary (3 to 35 centimeters thick)

^Cu1--8 to 23 centimeters; light yellowish brown (10YR 6/4) clay loam, dark yellowish brown (10YR 4/4) moist; massive; hard, very firm, very sticky, very plastic; finely disseminated free carbonates and common medium distinct irregular carbonate masses (assumed to be inherited from fill) in the matrix; 3 percent gravel; 1 percent artifacts of asphalt; slightly effervescent; slightly alkaline (pH 7.7); clear smooth boundary

^Cu2--23 to 46 centimeters; yellowish brown (10YR 5/4) gravelly-artifactual clay loam, dark yellowish brown (10YR 4/4) moist; massive; hard, very firm, very sticky, very plastic; common patchy distinct clay films on surfaces along pores (assumed to have been inherited from fill); finely disseminated free in the matrix; 6 percent gravel; 10 percent artifacts of concrete and asphalt; strongly effervescent; neutral (pH 7.0); clear smooth boundary

^2C1--46 to 108 centimeters; yellowish brown (10YR 5/4) clay loam, brown (10YR 4/3) moist; massive; hard, very firm, very sticky, very plastic; finely disseminated free carbonates in the matrix; 2 percent gravel; strongly effervescent; neutral (pH 7.3); clear smooth boundary

^2C2--108 to 200 centimeters; yellowish brown (10YR 5/4) clay loam, dark yellowish brown (10YR 4/4) moist; massive; moderately hard, firm, moderately sticky, moderately plastic; finely disseminated free carbonates and common fine, distinct threads of carbonate in the matrix; 2 percent gravel; slightly effervescent; neutral (pH 7.2)

TYPE LOCATION:
Denver County, Colorado, located in the west-central part of the southern section of Westerly Creek Park

USGS Quadrangle: Commerce City, Colorado
Latitude: 39.7511444
Longitude: -104.8807139
Datum: WGS84
Coordinate source: Hand-held GPS

RANGE IN CHARACTERISTICS:
Thickness of human-transported material: 50 to greater than 200 centimeters
Depth to paralithic contact: 100 to greater than 150 centimeters
Depth to seasonal highwater table: Greater than 150 centimeters
Linear extensibility: From 6.0 and 10.0 between 0 and 100 centimeters
Soil reaction: Neutral to moderately alkaline (pH 7.0 to 8.4)
Depth to free carbonates: 0 to 50 centimeters
Particle-size control section (weighted average):
Clay content--35 to 45 percent
Sand content--15 to 30 percent
Rock fragment content--0 to 5 percent
Artifact content--less than 10 percent, by volume; some individual horizons have more than 10 percent artifacts

^A(u) horizons:
Hue--7.5YR or 10YR
Value--3 to 6 dry; 1 to 4 moist
Chroma--2 to 5 dry; 1 to 4 moist
Texture (less than 2 mm fraction)-- clay, clay loam, loam, silty clay loam
Clay content--24 to 45 percent
Rock fragment content--0 to 14 percent gravel
Artifact content--0 to 14 percent
Calcium carbonate equivalent--0 to 5 percent
Reaction--Neutral to moderately alkaline (pH 7.2 to 8.0)

^Cu horizons (where present):
Hue--10YR
Value--3 to 6 dry; 3 to 5 moist
Chroma--2 or 4 dry; 1 to 5 moist
Texture (less than 2 mm fraction)-- clay, clay loam, sandy clay loam, silty clay, silty clay loam
Clay content--20 to 45 percent
Rock fragment content--0 to 20 percent gravel
Artifact content--1 to 15 percent
Calcium carbonate equivalent--0 to 10 percent
Reaction--Neutral to moderately alkaline (pH 7.0 to 8.2)

^C and/or ^C' horizon(s) (where present):
Hue--7.5YR or 10YR
Value--4 to 6 dry; 3 to 5 moist
Chroma--1 to 6 moist or dry
Texture (less than 2 mm fraction)-- clay, clay loam, sandy clay loam, silty clay, silty clay loam,
Clay content--25 to 50 percent
Rock fragment content--0 to 10 percent gravel
Calcium carbonate equivalent--5 to 14 percent
Reaction--Neutral to moderately alkaline (pH 7.0 to 8.2)

2C(k) horizons (when present):
Hue--7.5YR or 10YR
Value--4 to 6 dry; 3 or 4 moist
Chroma--3 or 5 dry; 2 to 5 moist
Texture (less than 2 mm fraction)--clay, clay loam, sandy clay loam, silty clay, silty clay loam
Clay content--28 to 50 percent
Rock fragment content--0 to 3 percent gravels
Calcium carbonate equivalent--5 to 14 percent
Reaction--Slightly to moderately pH 7.6 to 8.4

COMPETING SERIES:
There are currently no competing series; the Bodot soils in a similar family did not form in human-transported materials.

GEOGRAPHIC SETTING:
Parent material: Thick clayey human-transported material over loess or alluvium derived from loess
Landform: Fills and other leveled areas on loess-mantled plains and on floodways within loess-mantled plains
Slope ranges: 0 to 10 percent
Elevation: 1,580 to 1,720 meters
Frost-free period: 135 to 165 days
Mean annual air temperature: 10 to 12 degrees C
Mean annual precipitation range: 355 to 430 millimeters
Climate: Cold, dry winters and hot summers with North American monsoon precipitation from July through August. The driest months are December through February.

GEOGRAPHICALLY ASSOCIATED SOILS:
These are the Denver, Elyria, Globeville, Milehigh, and Weld soils.

Denver soils are found in similar landscape positions or nearby strath terraces, have mollic epipedons, argillic horizons, and formed in loess.
Elyria soils are found on adjacent fills of plains or stream terraces, have a fine-loamy particle-size control section, and formed in human-transported material over mixed eolian deposits or alluvium.
Globeville soils are found on adjacent fills on stream terraces have a fine-loamy particle-size control section and formed in human-transported material over alluvium.
Milehigh soils are found on nearby fills on stream terraces, have a coarse-loamy particle size-control section, a nonacid reaction class, and formed in human-transported material over alluvium.
Weld soils are found on adjacent plains, have mollic epipedons, argillic horizons and, formed in loess.

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
Drainage class: Well drained
Saturated hydraulic conductivity: Moderately low (0.04 to 0.36 cm/sec)
Flooding: None to occasional with very brief duration from March through August
Ponding: None

Some pedons are saturated below 120 centimeters for brief periods.

USE AND VEGETATION:
Most areas are primarily used for urban development. Vegetation may include a mix of managed and unmanaged plant communities with a mix of native and non-native species. Many areas are vegetated with non-native ornamental landscaping and/or turfgrass associated with developed land uses. Some areas may exhibit weedy, invasive, and/or primary succession vegetation communities (e.g., abandoned lots and other unmanaged areas). The potential native vegetation is fourwing saltbush, winterfat, western wheatgrass, and blue grama.

DISTRIBUTION AND EXTENT:
Urban and other areas with human-modified landscapes on loess-mantled plains, primarily on the east bank of the South Platte River in the vicinity of Denver in north-central Colorado. MLRA 67B - Central High Plains, Southern Part. These soils are of small extent.

SOIL SURVEY REGION (SSR) RESPONSIBLE: Raleigh, North Carolina (Special Projects Office)

SERIES ESTABLISHED: Denver County, Colorado 2025.

REMARKS:
Typical Pedon Taxonomic Features:
Ochric epipedon--The zone from 0 to 8 centimeters (^Au horizon)
Human-transported materials--The zone from 0 to 200 centimeters (All horizons)
Free carbonates--The zone from 0 to 200 centimeters (All horizons)
Artifacts--The zone from 0 to 46 centimeters (^Au, ^Cu1, and ^Cu2)
Particle-size control section--The zone from 25 to 100 centimeters
Taxonomic version: Keys to Soil Taxonomy, 13th edition, (2022)
Other: Racas is a coined name associated with an acronym for the Denver Soil Survey inventory protocol. A small number of Racas pedons in Denver County Area, Colorado (CO031) have paralithic contacts below 100 centimeters and have been classified as taxadjuncts as a best fit. If found to be common after more investigation, a new soil series should be established.

ADDITIONAL DATA:
NASIS User Pedon ID: 2020CO031565

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National Cooperative Soil Survey
U.S.A.