LOCATION STEADISON               OR

Tentative Series
SCW/KLM/MPR
02/2025

STEADISON SERIES

Landscape--plateaus
Landform--fan remnants
Slope--2 to 50 percent
Parent Material--colluvium and residuum derived from Rattlesnake Formation fanglomerate
Mean annual precipitation--380 mm
Mean annual air temperature--9 degrees C
Depth class--very shallow
Drainage class--well drained
Soil moisture regime--xeric
Soil temperature regime--mesic
Soil moisture subclass--typic

TAXONOMIC CLASS: Clayey-skeletal, smectitic, mesic, shallow Typic Argixerolls

TYPICAL PEDON: Steadison very gravelly sandy clay loam, rangeland, on a 43 percent south facing slope at an elevation of 960 m (When described on September 15, 2015, the soil was dry throughout.)

A--0 to 3 cm; very gravelly sandy clay loam, brown (10YR 5/3) dry, dark brown (10YR 3/3) moist; moderate fine granular structure; slightly hard, friable, slightly sticky and slightly plastic; common very fine roots; common very fine irregular pores; 25 percent gravel and 15 percent cobbles; slightly alkaline (pH 7.6); abrupt smooth boundary (3 to 8 cm thick)

Bt--3 to 10 cm; very gravelly clay, brown (10YR 4/3) dry, dark brown (10YR 3/3) moist; moderate medium subangular blocky structure; hard, firm, moderately sticky and very plastic; common very fine roots; few very fine tubular pores; many distinct clay films on ped faces and pore linings; 15 percent coarse gravel and 20 percent fine gravel; moderately alkaline (pH 8.0); clear wavy boundary

Cd--10 cm; densic, fanglomerate bedrock that crushes to extremely gravelly loamy sand, brown (7.5YR 5/3) dry, brown (7.5YR 4/3) moist; massive; extremely hard, slightly rigid, nonsticky and nonplastic; 65 percent rounded gravel; moderately alkaline (pH 8.0).

TYPE LOCATION: Grant County, Oregon, about 3.2 km southeast of the town of Mt. Vernon; about 276 m south and 59 m east of the NW corner of section 35, T. 13 S., R. 30 E.
Latitude-- 44.40065
Longitude-- -119.08221
Datum--WGS84 (coordinates determined with a GPS)
RANGE IN CHARACTERISTICS:
Mean annual soil temperature--8 to 11 degrees C
Soil moisture--usually moist, but are dry 70 to 90 consecutive days during the four months following the summer solstice
Depth to densic bedrock--10 to 25 cm
Mollic epipedon--10 to 25 cm thick
Argillic horizon--5 to 18 cm thick

Particle size control section:
Clay content--35 to 45 percent
Total rock fragment content--35 to 50 percent, mostly as fine gravel
Rock fragment type--mixed lithologies derived from the Rattlesnake fanglomerate

A horizon
Hue--7.5YR or 10YR dry or moist
Value--4 or 5 dry, 2 or 3 moist
Chroma--2 or 3 dry or moist
Fine earth texture--loam, sandy clay loam
Clay content--20 to 30 percent
Sand content--30 to 60 percent
Organic matter--2 to 4 percent
Total rock fragments--15 to 50 percent
Gravel--15 to 35 percent
Cobbles--0 to 30 percent
Reaction--slightly alkaline to moderately alkaline

Bt horizon
Hue-- 5YR, 7.5YR, 10YR, or 2.5Y dry or moist
Value--4 or 5 dry, 3 or 4 moist
Chroma--3 or 4 dry or moist
Fine earth texture-- clay loam, or clay
Clay content--35 to 50 percent
Sand content--15 to 45 percent
Total rock fragments--35 to 50 percent
Fine gravel--0 to 15 percent
Gravel--15 to 50 percent
Cobbles--0 to 20 percent
Reaction--slightly alkaline to moderately alkaline

Cd horizon
Hue-- 5YR, 7.5YR, 10YR, dry or moist
Value--4 or 5 dry, 3 to 4 moist
Chroma--3 or 4 dry or moist
Fine earth texture--loamy sand
Clay content--35 to 55 percent
Fine earth texture--after crushing; loamy sand
Clay content--0 to 10 percent
Sand content--70 to 90 percent
Organic matter--0 percent
Total rock fragments--60 to 90 percent (gravel)

COMPETING SERIES:
Starkey--25 to 50 cm to paralithic contact

GEOGRAPHIC SETTING:
Elevation--850 to 1220 m
Climate--cool, wet winters and hot, dry summers
Mean annual precipitation--305 to 455 mm
Mean annual air temperature 8 to 10 degrees C
Frost-free period--80 to 120 days

GEOGRAPHICALLY ASSOCIATED SOILS:
Belshaw-- occur on benches and adjacent hillslopes; greater than 150 cm to restrictive feature
Grell-- occur on very steep south facing slopes; average less than 35% clay and more than 35% rock fragments in the control section
Hack--occur on footslopes and fans; average between 18 and 35% clay in the PSCS
Oliver--occur on benches and fan remnants; 25 to 50 cm to ultramafic bedrock
Plaiden--occur on fan remnants; 50 to 100 cm to densic bedrock
Whipsteen--occur on fan remnants; 25 to 50 cm to densic bedrock

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
Drainage--well drained
Saturated hydraulic conductivity (Ksat)--moderately low

USE AND VEGETATION:
Use--livestock grazing, wildlife habitat
Vegetation--bluebunch wheatgrass, Idaho fescue, Sandberg bluegrass

DISTRIBUTION AND EXTENT:
East-central Oregon; MLRA 9, 10; small extent

SOIL SURVEY REGIONAL OFFICE (SSRO) RESPONSIBLE: Bozeman, Montana

SERIES PROPOSED:
Grant County, Oregon 2/2016; The name is coined

REMARKS:
Diagnostic horizons and features in this pedon are:
Particle size control section--0 to 10 cm
Mollic epipedon--0 to 10 cm
Argillic horizon--3 to 10 cm
Densic contact--10 cm
Xeric moisture regime

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National Cooperative Soil Survey
U.S.A.