LOCATION WINTERIM                OR

Established Series
Rev. RHB-RWL-JVC-JBF
06/2011

WINTERIM SERIES

The Winterim series consists of deep, well drained soils that formed in colluvium and residuum derived from basalt and tuff. Winterim soils are on plateaus. Slopes are 0 to 60 percent. The mean annual precipitation is about 760 mm and the mean annual temperature is about 7 degrees C.

TAXONOMIC CLASS: Clayey-skeletal, smectitic, frigid Pachic Argixerolls

TYPICAL PEDON: Winterim very gravelly loam--on an 18 percent southwest-facing slope under ponderosa pine--forestland. (Colors are for moist soil unless otherwise noted.) The soil surface is covered with about 3 cm of ponderosa pine needles.

A--0 to 13 cm; black (10YR 2/1) very gravelly loam, very dark grayish brown (10YR 3/2) dry; moderate fine granular structure; slightly hard, very friable, moderately sticky and moderately plastic; many roots; many irregular pores; 5 percent stones, 5 percent cobbles, and 25 percent gravel; slightly acid (pH 6.5); clear smooth boundary. (10 to 38 cm thick)

Bt1--13 to 30 cm; dark brown (7.5YR 3/2) gravelly clay loam, brown (7.5YR 4/2) dry; weak medium subangular blocky structure parting to moderate fine granular; hard, friable, very sticky and moderately plastic; many roots; common very fine and fine tubular pores; few faint clay films on faces of peds; 5 percent cobbles and 15 percent gravel; slightly acid (pH 6.5); clear wavy boundary. (15 to 46 cm thick)

Bt2--30 to 53 cm; dark reddish brown (5YR 3/3) very gravelly clay, reddish brown (5YR 4/3) dry; moderate fine and medium subangular structure; hard, firm, very sticky and very plastic; common roots; common very fine and fine tubular pores; common faint clay films on faces of peds and lining tubular pores; 5 percent stones, 10 percent cobbles, and 40 percent gravel; slightly acid (pH 6.3); clear wavy boundary. (18 to 46 cm thick)

Bt3--53 to 114 cm; dark reddish brown (5YR 3/4) very gravelly clay, reddish brown (5YR 4/4) dry; moderate medium angular blocky structure; very hard, very firm, very sticky and very plastic; few roots; common very fine and fine tubular pores; many distinct clay films on faces of peds and lining tubular pores; 35 percent gravel; slightly acid (pH 6.3); gradual boundary. (38 to 76 cm thick)

Cr--114 cm; weathered basalt.

TYPE LOCATION: Lake County, Oregon; on the Fremont National Forest about 9 miles east-southeast of Lakeview; in the SE 1/4 of the NW 1/4 of section 30, T. 39 S., R. 22 E.; USGS Horse Prairie 7.5 minute topographic quadrangle; approximately latitude 42 degrees 09 minutes 36 seconds N and longitude 120 degrees 10 minutes 16 seconds W; NAD 83.

RANGE IN CHARACTERISTICS:
Soil moisture: Usually moist in winter and spring; dry for 80 to 100 consecutive days following the summer solstice; xeric moisture regime.
Mean annual soil temperature: 7 to 8 degrees C.
Mollic epipedon thickness: 50 to 76 cm; includes the Bt1 and Bt2 horizons.
Depth to base of argillic horizon: 100 to 150 cm.
Depth to bedrock:100 to 150 cm are weathered volcanic rock such as basalt.
Base saturation (sum of cations): 75 to 85 percent.
Reaction: Slightly acid or neutral.

Particle-size control section - Clay content: Averages 35 to 50 percent.
Rock fragments: Averages 35 to 60 percent, mainly gravel. Lithology of fragments are volcanic rocks such as basalt and tuff.

A horizon
Hue: 10YR or 7.5YR.
Value: 2 or 3 moist, 3 through 5 dry.
Chroma: 1 or 2, moist or dry.
Organic matter content: 2 to 5 percent.

Bt1 horizon
Hue: 7.5YR or 5YR.
Value: 3 or 4 moist, 4 or 5 dry.
Chroma: 2 or 3, moist or dry.
Texture: Gravelly loam or gravelly clay loam.
Clay content: 25 to 30 percent.
Rock fragments: 15 to 35 percent total; 0 to 10 percent cobbles, 0 to 5 percent stones, and 15 to 35 percent gravel.
Organic matter content: 1 to 3 percent.

Bt2 horizon
Hue: 7.5YR or 5YR.
Value: 3 or 4 moist, 4 or 5 dry.
Chroma: 2 or 3, moist or dry.
Texture: Very gravelly clay loam or very gravelly clay.
Clay content: 35 to 50 percent.
Rock fragments: 35 to 60 percent total; 0 to 10 percent cobbles, 0 to 5 percent stones, and 35 to 55 percent gravel.
Organic matter content: 1 to 3 percent.

Bt3 horizon
Hue: 7.5YR or 5YR.
Value: 3 or 4 moist, 4 through 6 dry.
Chroma: 2 through 4, moist or dry.
Clay content: 40 to 50 percent.
Rock fragments: 35 to 60 percent total; 0 to 10 percent cobbles, 0 to 5 percent stones,and 35 to 55 percent gravel.

COMPETING SERIES: These are the Hamtah, Longbranch, Mendeboure, Royst, and Snell series.

Hamtah soils are intermittently moist in some part of the moisture control section for 10 to 20 cumulative between July and September following summer convection storms. Longbranch soils have identifiable secondary carbonates in the lower part of the argillic horizon. Mendeboure, Royst, and Snell soils are moderately deep to lithic contacts.

GEOGRAPHIC SETTING: Winterim soils are on plateaus. These soils formed in colluvium and residuum derived from basalt and tuff. Slopes are 0 to 60 percent. Elevations range from 1,480 to 2,000 meters. The climate is subhumid with cool, moist winters and warm, dry summers. The mean annual precipitation is 500 to 800 mm, the mean annual temperature is 6 to 7 degrees C, and the frost-free period is 30 to 50 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Booth, Rogger, Sherval, and Woodchopper soils. Booth soils are fine textured. Rogger soils are loamy-skeletal and have mollic epipedons 25 to 50 cm thick. Sherval soils are loamy-skeletal. Woodchopper soils are fine textured, have isotic mineralogy, and have base saturation by sum of cations of 50 to 75 percent throughout the upper 760 cm of the solum.

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Well drained; very high surface runoff; moderately low saturated hydraulic conductivity.

USE AND VEGETATION: Winterim soils are used for timber production, watershed, wildlife habitat, recreation, and livestock grazing. The vegetation is a forest canopy of ponderosa pine and western juniper with an understory of antelope bitterbrush, squawcarpet, and grasses.

DISTRIBUTION AND EXTENT: South-central Oregon. These soils are moderately extensive. MLRA 21.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California.

SERIES ESTABLISHED: Lake County, Oregon, Southern Part, 1991.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - The zone from the soil surface to 53 cm (A, Bt1, and Bt2 horizons).
Argillic horizon - The zone from 30 to 114 cm (Bt1, Bt2, and Bt3 horizons).
Paralithic contact - The boundary at 114 cm to underlying weathered bedrock (Cr layer).
Particle-size control section - The zone from 30 to 81 cm (Bt1 and Bt2 horizons and part of the Bt3 horizon).

ADDITIONAL DATA: OSU laboratory data S83OR-37-1; Forest Service site CP-F1-11.

---

National Cooperative Soil Survey
U.S.A.