LOCATION RIDDLEFIELD OR
Tentative Series
Rev. EN/CEG
09/2025
RIDDLEFIELD SERIES
Landscape--intermontane basin
Landform--fault scarps
Slope--10 to 70 percent
Parent material--colluvium weathered from basalt, tuff, or andesite, with an influence of volcanic ash from eolian deposits in the upper part
Mean annual precipitation--about 450 mm
Mean annual air temperature--about 6 degrees C
Depth class--very deep
Drainage class--well drained
Soil moisture regime--xeric
Soil temperature regime--frigid
Soil moisture subclass--typic
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, frigid Vitrandic Argixerolls
TYPICAL PEDON: Riddlefield gravelly ashy loam, on a south-southwest-facing (209 degree) 38 percent slope in ponderosa pine-juniper woodland at 1585 m elevation; 1 percent surface-cover of stones (The soil was moist throughout when described on May 5, 2005.)
Oi--0 to 2 cm; slightly decomposed plant material from needles, twigs, cones and leaves; very strongly acid (pH 5.0); abrupt broken boundary.
A--2 to 27 cm; gravelly ashy loam, dark grayish brown (10YR 4/2) dry, very dark grayish brown (10YR 3/2) moist; moderate fine subangular blocky structure; slightly hard, friable, moderately sticky and moderately plastic; many very fine, common fine and medium, and few coarse roots throughout; few very fine dendritic tubular pores; 15 percent gravel, 2 percent cobbles, and 1 percent stones; neutral (pH 6.8); clear wavy boundary.
AB--27 to 55 cm; very cobbly ashy sandy loam, brown (10YR 4/3) dry, very dark grayish brown (10YR 3/2) moist; moderate medium subangular blocky structure; slightly hard, friable, moderately sticky and moderately plastic; common very fine and fine, and few medium and coarse roots throughout; few very fine dendritic tubular pores; 15 percent gravel, 25 percent cobbles, and 5 percent stones; neutral (pH 6.8); clear wavy boundary.
Bt1--55 to 90 cm; very cobbly sandy clay loam, 60 percent brown (10YR 4/3) and 40 percent brown (10YR 5/3) dry, 60 percent dark brown (10YR 3/3) and 40 percent brown (10YR 4/3) moist; moderate medium subangular blocky structure; moderately hard, friable, moderately sticky and moderately plastic; common very fine and fine and few medium roots throughout; few very fine and fine dendritic tubular pores; 60 percent faint clay films, brown (7.5YR 4/3) moist, on all faces of peds and on rock fragments; 30 percent gravel, 20 percent cobbles, and 5 percent stones; neutral (pH 6.6); clear wavy boundary.
Bt2--90 to 150 cm; very cobbly sandy clay loam, brown (7.5YR 5/4) dry, brown (7.5YR 4/3) moist; weak medium subangular blocky structure; hard, firm, moderately sticky and moderately plastic; few very fine, fine, and medium roots throughout; few fine dendritic tubular pores; 1 percent distinct clay films, brown (7.5YR 4/4) moist, on surfaces along pores and 20 percent distinct clay films, brown (7.5YR 4/4) moist, on all faces of peds and on rock fragments; 30 percent gravel, 20 percent cobbles, and 2 percent stones; neutral (pH 6.6).
TYPE LOCATION: Klamath County, Oregon; about 4 miles south and 1 mile west of the town of Sprague River, Oregon; about 783 m south and 619 m west of the northeast corner of Section 3, Township 37 S, Range 11 1/2 E; Willamette Meridian; Sprague River West, Oregon USGS 7.5 minute topographic quadrangle; latitude 42.3926201 degrees north, longitude 121.5141525 degrees west, datum WGS 84 (coordinates derived from GPS unit)
RANGE IN CHARACTERISTICS:
Soil Temperature: frigid regime
Mean annual soil temperature-- 5 to 8 degrees C
Moisture control section--10 to 30 cm; dry for 60 to 90 consecutive days within the four month period following the summer solstice
Thickness of mollic epipedon--50 to 95 cm
Particle-size control section
*Clay content--18 to 30 percent
*Rock fragment content--35 to 75 percent
Estimated properties, A and AB horizon(s):
*Ammonium oxalate extractable Al plus 1/2 Fe--0.2 to 0.4 percent
*P-retention--10 to 25 percent
*Volcanic glass content--6 to 30 percent
*1/3-bar bulk density--1.00 to 1.35 g/cm3
*1500 kPa water (air-dried samples)--10 to 15 percent
A horizons
Hue--7.5YR, 10YR
Value--2 or 3 moist, 3 to 5 dry
Chroma--2 or 3, moist or dry
Clay content--12 to 23 percent
Total rock content--15 to 35 percent
Gravel content--10 to 20 percent
Cobble content--0 to 10 percent
Stone content--0 to 5 percent
Boulder content--0 to 2 percent
Reaction--slightly acid or neutral (pH 6.1 to 7.3)
Organic matter content--2.0 to 10.0 percent
Thickness--15 to 35 cm
AB horizons
Hue--7.5 YR or 10YR, moist or dry
Value--3 moist, 4 or 5 dry
Chroma--2 or 3, moist or dry
Fine-earth texture--ashy sandy loam, ashy loam
Clay content--15 to 23 percent
Total rock content--35 to 60 percent
Gravel content--10 to 25 percent
Cobble content--10 to 25 percent
Stone content--5 to 15 percent
Boulder content--0 to 2 percent
Reaction--slightly acid or neutral (pH 6.1 to 7.3)
Organic matter content--0.5 to 4.0 percent
Thickness--20 to 60 cm
Bt horizons
Hue--7.5 YR or 10YR, moist or dry
Value--3 or 4 moist, 4 to 6 dry
Chroma--3 to 5, moist or dry
Fine-earth texture--loam, sandy clay loam
Clay content--18 to 30 percent
Total rock content--35 to 80 percent
Gravel content--15 to 35 percent
Cobble content--15 to 35 percent
Stone content--2 to 15 percent
Boulder content--0 to 5 percent
Reaction--slightly acid or neutral (pH 6.1 to 7.3)
Organic matter content--0.1 to 2.0 percent
Thickness--greater than 105 cm
COMPETING SERIES:
Conwayridge--10 to 18 percent clay in the particle-size control section
Ginserly--lithic contact between 100 and 150 cm (deep)
Imnaha--lithic contact between 50 and 100 cm (moderately deep)
Masonic--paralithic contact between 50 and 100 cm (moderately deep)
Needhill--lithic contact between 100 and 150 cm (deep)
Roundbarn--paralithic contact between 100 and 150 cm (deep)
Saturday--lithic contact between 100 and 150 cm (deep)
Skullhollow--lithic contact between 63 and 100 cm (moderately deep)
Wilt--lithic contact between 50 and 100 cm (moderately deep)
GEOGRAPHIC SETTING:
Elevation--1310 to 2100 m
Climate--cold, moist winters and cool, dry summers
Mean annual air temperature-- 4 to 7 degrees C
Mean annual precipitation--350 to 840 mm
Frost-free period--50 to 70 days
GEOGRAPHICALLY ASSOCIATED SOILS:
Bly--on alluvial fans and terraces; fine-loamy particle-size class; deep to a duripan or very deep
Royst--on hillslopes and scarp slopes; clayey-skeletal particle-size class; moderately deep to paralithic contact and to lithic contact with basalt
Vitrassun--on rock pediments, sand ramps and depressions on rock pediments, and scarps on lava flows; loamy particle-size class with less than 35 percent rock fragments; shallow to a lithic contact with volcanic rock
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
Drainage class--well drained
Saturated hydraulic conductivity (Ksat)--moderately high in the A horizon; moderately high to high in the AB horizon; moderately high in the Bt horizons
USE AND VEGETATION:
Use-- timber production, livestock grazing, and wildlife habitat
Vegetation--ponderosa pine, western juniper, curlleaf mountain mahogany, antelope bitterbrush, mountain big sagebrush, Idaho fescue
DISTRIBUTION AND EXTENT: Klamath and Shasta Valleys and Basins, Oregon; MLRA 21; small extent
SOIL SURVEY REGIONAL OFFICE (SSRO) RESPONSIBLE: Davis, California
SERIES PROPOSED:
Klamath County Oregon, 2018
Origin of the name--the name is derived from a meadow near where this soil is mapped; the meadow is named "Riddle Field" on the USGS topographic map
REMARKS:
Diagnostic horizons and features in this pedon
*Mollic epipedon--zone from 2 to 90 cm
*Volcanic glass--zone from 2 to 55 cm
*Argillic horizon--zone from 55 to 200 cm
*Particle-size control section--zone from 55 to 105 cm
ADDITIONAL DATA:
NASIS Site ID--05-JFD-08; NASIS Pedon ID--05OR683008
National Cooperative Soil Survey
U.S.A.