LOCATION DEADWILMA OR
Tentative Series
IRD. KLM/DEW
08/2025
DEADWILMA SERIES
Landscape--lava plateaus
Landform--basins, lava flows
Slope--0 to 20 percent
Parent Material--Newberry pumice over Mazama volcanic ash over old alluvium or lacustrine deposits
Mean annual precipitation--260 mm
Mean annual air temperature--6.5 degrees C
Depth class--very deep
Drainage class--somewhat excessively drained
Soil moisture regime--aridic
Soil temperature regime--frigid
Soil moisture subclass--typic
TAXONOMIC CLASS: Pumiceous, glassy, frigid Vitrandic Torriorthents
TYPICAL PEDON: Deadwilma paragravel, rangeland, on a 5 percent slope at an elevation of 1470 meters. (Colors are for dry soil unless otherwise noted.)
A1--0 to 7 centimeters; light brownish gray (2.5Y 6/2) paragravel, grayish brown (2.5Y 5/2) moist; single grain; loose, nonsticky, nonplastic; few fine roots throughout; many very fine, fine, and medium interstitial pores; 95 percent pumice paragravel; neutral (pH 6.7); clear smooth boundary.
A2--7 to 20 centimeters; grayish brown (2.5Y 5/2) extremely paragravelly ashy loamy coarse sand, very dark grayish brown (10YR 3/2) moist; weak very fine granular structure; loose, very friable, nonsticky, nonplastic; common very fine and few fine roots throughout; many very fine and fine interstitial pores; 80 percent pumice paragravel; neutral (pH 6.7); gradual smooth boundary.
C--20 to 93 centimeters; light brownish gray (2.5Y 6/2) paragravel, grayish brown (2.5Y 5/2) moist; single grain; loose, nonsticky, nonplastic; few very fine, medium, and coarse roots throughout; many very fine, fine, and medium interstitial pores; 92 percent pumice paragravel; neutral (pH 6.7); abrupt smooth boundary.
2Bw1--93 to 155 centimeters; brown (10YR 5/3) ashy loamy sand, dark brown (10YR 3/3) moist; weak medium subangular blocky structure; soft, very friable, nonsticky, nonplastic; few very fine roots throughout; few very fine irregular and few fine dendritic tubular pores; 2 percent pumice paragravel and 10 percent basalt gravel; neutral (pH 7.0); clear smooth boundary.
3Bw2--155 to 178 centimeters; brown (10YR 5/3) gravelly loamy sand, dark brown (10YR 3/3) moist; weak medium subangular blocky structure; soft, very friable, nonsticky, nonplastic; few very fine roots throughout; few very fine irregular and few fine dendritic tubular pores; 20 percent basalt gravel; neutral (pH 7.1).
TYPE LOCATION: Deschutes County, Oregon; NW 1/4, SW 1/4 section 15, T. 21 S., R. 16 E.; Latitude 43.7506260, Longitude -120.7933090, datum WGS84 (coordinates determined with a GPS).
RANGE IN CHARACTERISTICS:
Mean annual soil temperature--6 to 8 degrees C
Soil moisture--Soils are moist in winter and spring. They are warmer than 5.0 degrees C from April 15 to November 1, and they are dry throughout after July 1
Depth to buried soil--90 to 120 cm
Thickness of ash influenced layers--less than 30 cm within the particle size control section. Buried Mazama ash may be present below 90 cm
Thickness of Newberry pumice dominated layers--55 to 90 cm within the particle size control section
Estimated properties of layers influenced by volcanic ash
Ammonium oxalate extractable Al + Fe--0.02 to 0.14 percent
1500 kPa water content (air dry)--3 to 12 percent
0.02 to 2.0 mm fraction--75 to 100 percent
Medium to very coarse sand in the .02 to 2.0 mm fraction--greater than 50 percent
Volcanic glass in the 0.02 to 2.0 mm fraction--40 to 90 percent
P retention--0 to 25 percent
Particle-size control section: 25 to 100 cm
Clay content, weighted average--0 to 4 percent
Fragment content, weighted average--60 to 95 percent
A1 horizon
Hue--2.5Y
Value--4 to 7
Chroma--1 to 3
In-lieu texture--paragravel
Fine-earth texture (if present)--ashy loamy coarse sand or ashy sand
Clay content--0 to 2 percent
Sand content--80 to 100 percent
Organic matter--0.25 to 1.5 percent
Total fragment content--85 to 100 percent
Pumice paragravel--85 to 100 percent
Reaction--6.6 to 7.3 (neutral)
Thickness--2 to 15 cm
A2 horizon
Hue--2.5Y or 10YR
Value--3 or 4 moist, 4 to 6 dry
Chroma--1 to 3
Fine-earth texture--ashy loamy coarse sand or ashy loamy sand
Clay content--0 to 4 percent
Sand content--80 to 95 percent
Organic matter--0.5 to 2.0 percent
Total fragment content--70 to 90 percent
Pumice paragravel--70 to 90 percent
Reaction--6.6 to 7.3 (neutral)
Thickness--5 to 15 cm
C horizon
Hue--2.5Y
Value--4 to 7 moist, 6 to 8 dry
Chroma--2 to 4
In-lieu texture--paragravel
Fine-earth texture (if present)--ashy sand
Clay content--0 to 2 percent
Sand content--90 to 100 percent
Organic matter--0.0 to 0.5 percent
Total fragment content--90 to 95 percent
Pumice paragravel--90 to 95 percent
Reaction--6.6 to 7.3 (neutral)
Thickness--60 to 100 cm
2Bw1 horizon (buried Mazama ash layer)
Note: Some pedons may have weak silica accumulation (Bq horizons) in this zone
Hue--10YR
Value--3 or 4 moist, 4 or 5 dry
Chroma--3 to 6
Fine earth texture--ashy sandy loam, ashy loamy sand, or ashy loamy coarse sand
Clay content--2 to 10 percent
Sand content--60 to 85 percent
Organic matter--0.0 to 1.0 percent
Total fragment content--0 to 20 percent
Pumice paragravel (fine)--0 to 4 percent
Gravel--0 to 20 percent
Reaction--6.6 to 7.3 (neutral)
Thickness--30 to 80 cm
3Bw2 horizon (buried alluvium or lacustrine deposits)
Hue--10YR
Value--3 or 4 moist, 4 or 5 dry
Chroma--3 to 6
Fine earth texture--loamy sand, sandy loam, loam, or silt loam
Clay content--5 to 15 percent
Sand content--30 to 85 percent
Organic matter--0.0 to 1.0 percent
Total fragment content--0 to 60 percent
Gravel--0 to 60 percent
Reaction--6.6 to 7.8 (neutral to slightly alkaline)
COMPETING SERIES:
There are no competing series
GEOGRAPHIC SETTING:
Elevation--1400 to 1500 m
Climate--cold, moist and warm, dry summers
Mean annual precipitation--230 to 300 mm
Mean annual air temperature--5.0 to 7.0 degrees C
Frost-free period--30 to 90 days
Lithology--volcanic pumice derived from Newberry Caldera over volcanic ash derived from Mazama over old alluvium or lacustrine deposits
GEOGRAPHICALLY ASSOCIATED SOILS:
Borobey--occur on valley floors and lake terraces; does not contain pumice paragravel; very deep (greater than 150 cm) to bedrock
Kotzman (proposed)--occur on lava flows; 50 to 100 cm to lithic contact
Stookmoor--occur on hillslopes, plateaus and structural benches; 50 to 100 cm to lithic contact
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
Drainage--somewhat excessively drained
Saturated hydraulic conductivity (Ksat)--high to very high
USE AND VEGETATION:
Use--livestock grazing, wildlife habitat
Potential native vegetation--mountain big sagebrush, antelope bitterbrush, western needlegrass, Ross sedge
Typical Ecological Site--Pumice Flat 10-12 PZ (R023XY508OR)
DISTRIBUTION AND EXTENT:
Central Oregon east of the Cascade Mountains; MLRA 23. The series is of small extent.
SOIL SURVEY REGIONAL OFFICE (SSRO) RESPONSIBLE: Bozeman, Montana
SERIES PROPOSED:
Deschutes County, Deschutes National Forest, Oregon 2025; name derived from the Deadwilma Fire 1977 and BLM grazing allotment
REMARKS:
Diagnostic horizons and features recognized in this pedon are:
Particle-size control section--25 to 100 cm (C and part of the 2Bw1 horizon)
Ochric epipedon--0 to 20 cm (A1 and A2 horizons)
Volcanic glass and pumice--0 to 155 cm (A1, A2, C, and 2Bw1 horizons)
Deadwilma series does not meet andic soil properties due to low Al & 1/2Fe and low P retention.
ADDITIONAL DATA:
Lab data available from nearby Dester series (Pedon ID: S2017OR017010)
National Cooperative Soil Survey
U.S.A.