LOCATION WINTERIM           OR

WINTERIM SERIES

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 1 inch of ponderosa pine needles.

A--0 to 5 inches; 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, 25 percent gravel; slightly acid (pH 6.5); clear smooth boundary. (4 to 15 inches thick)

Bt1--5 to 12 inches; 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. (6 to 18 inches thick)

Bt2--12 to 21 inches; 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. (7 to 18 inches thick)

Bt3--21 to 45 inches; 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. (15 to 30 inches thick)

Cr--45 inches; 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 42 degrees 09 minutes 36 seconds north latitude and 120 degrees 10 minutes 12 seconds west longitude, NAD27.

RANGE IN CHARACTERISTICS:

Soil moisture - These soils are moist in winter and spring; dry for 80 to 100 consecutive days following the summer solstice; Xeric moisture regime.

Mean annual soil temperature - 45 to 47 degrees F.

Mollic epipedon thickness - 20 to 30 inches; includes the Bt1 and Bt2 horizons.

Depth to base of argillic horizon - 40 to 60 inches.

Depth to bedrock - 40 to 60 inches to a paralithic contact. The paralithic materials below the contact are weathered volcanic rock such as basalt.

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.

Base saturation (sum of cations) - 75 to 85 percent.

Reaction - Slightly acid or neutral.

A horizon - Hue: 10YR or 7.5YR.
Value: 2 or 3 moist, 3 through 5 dry.
Chroma: 1 or 2, moist or dry.
Rock fragments: 0 to 20 percent cobbles and stones, 25 to 50 percent gravel.
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 5 percent cobbles and stones, 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 5 percent cobbles and stones, 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 5 percent cobbles and stones, 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 5,000 to 6,550 feet. The climate is subhumid with cool, moist winters and warm, dry summers. The mean annual precipitation is 28 to 32 inches, the mean annual temperature is 43 to 45 degrees F., 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 10 to 20 inches 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 30 inches of the solum.

DRAINAGE AND PERMEABILITY: Well drained; very high surface runoff; slow permeability.

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 OFFICE RESPONSIBLE: Reno, Nevada.

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 21 inches (A, Bt1, and Bt2 horizons).

Argillic horizon - The zone from 12 to 45 inches (Bt1, Bt2, and Bt3 horizons).

Paralithic contact - The boundary at 45 inches to underlying weathered bedrock (Cr layer).

Particle-size control section - The zone from 12 to 32 inches (Bt1 and Bt2 horizons and part of the Bt3 horizon).

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