LOCATION COOPERDRAW              OR

Established Series
Rev. CWL-MPK-JVC-JBF
12/2022

COOPERDRAW SERIES

The Cooperdraw series consists of moderately deep to a duripan, well drained soils that formed in alluvium derived from volcanic rocks. Cooperdraw soils are on fan remnants. Slopes are 1 to 5 percent. The mean annual precipitation is about 280 mm and the mean annual temperature is about 7 degrees C.

TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, frigid Xeric Argidurids

TYPICAL PEDON: Cooperdraw very gravelly sandy loam--on a fan remnant sloping 3 percent to the northeast at an elevation of 1,590 meters--rangeland. (Colors are for dry soil unless otherwise noted.)

A--0 to 5 cm; brown (10YR 5/3) very gravelly sandy loam, dark brown (10YR 3/3) moist; moderate medium granular structure; soft, very friable, slightly sticky and slightly plastic; many very fine and few fine roots; few fine irregular pores; 25 percent gravel, 10 percent cobbles, and 5 percent stones; slightly alkaline (pH 7.6); clear smooth boundary. (5 or 8 cm thick)

AB--5 to 20 cm; yellowish brown (10YR 5/4) gravelly loam, dark yellowish brown (10YR 3/4) moist; strong medium granular structure; soft, very friable, slightly sticky and slightly plastic; common very fine, few fine, and few medium roots; few fine irregular pores; 15 percent gravel and 5 percent cobbles; slightly alkaline (pH 7.6); abrupt smooth boundary. (13 or 15 cmthick)

Btk--20 to 36 cm; pale brown (10YR 6/3) very cobbly clay loam, brown (10YR 4/3) moist; moderate medium subangular blocky structure; slightly hard, friable, moderately sticky and moderately plastic; common very fine, few fine, and few medium roots; few fine irregular pores; 25 percent gravel, 15 percent cobbles, 5 percent stones; common distinct clay films on faces of peds; secondary carbonates segregated as few fine coats on bottoms of rock fragments; slightly effervescent; slightly alkaline (pH 7.8); clear smooth boundary. (15 to 25 cm thick)

Bkq--36 to 61 cm; light yellowish brown (10YR 6/4) very cobbly sandy loam, dark yellowish brown (10YR 4/4) moist; massive; slightly hard, friable, brittle, slightly sticky and slightly plastic; few very fine, few fine, and few medium roots; few fine irregular pores; 20 percent gravel, 15 percent cobbles, and 5 percent stones; 15 percent strongly cemented and indurated pebble-size duripan fragments; secondary carbonates segregated as common fine and medium coats on rock and duripan fragments; violently effervescent; moderately alkaline (pH 8.4); abrupt smooth boundary. (0 to 25 cm thick)

Bkqm1--61 to 97 cm; pale brown (10YR 6/3) cemented material, brown (10YR 4/3) moist; massive; few very fine roots; few fine irregular pores; an indurated laminar opaline silica cap 2 to 4 cm thick over a strongly cemented matrix that is brittle when moist; secondary carbonates segregated as filaments and coats along fractures; strongly effervescent; moderately alkaline (pH 8.4); clear smooth boundary. (8 to 36 cm thick)

Bkqm2--97 to 152 cm; very pale brown (10YR 7/4) cemented material, light yellowish brown (10YR 6/4) moist; massive; indurated by secondary silica and carbonates; secondary carbonates segregated as filaments and coats along fractures; strongly effervescent; moderately alkaline (pH 8.4).

TYPE LOCATION: Lake County, Oregon; about 10 miles east of Lake Abert; approximately 1,200 feet north and 2,250 feet west of the southeast corner of section 20, T. 34 S., R. 23 E.; USGS Cooper Draw 7.5 minute topographic quadrangle; latitude 42 degrees 36 minutes 11 seconds N and longitude 120 degrees 01 minute 57 seconds W;, NAD 83.

RANGE IN CHARACTERISTICS:
Soil moisture: Usually moist in the moisture control section in winter and early spring, dry in summer and fall; aridic moisture regime that borders on xeric.
Mean annual soil temperature: 7 to 8 degrees C.
Ochric epipedon thickness: 18 to 23 cm.
Depth to base of argillic horizon: 33 to 50 cm.
Depth to duripan: 50 to 100 cm.
Duripan thickness: 50 to 90 cm.
Depth to bedrock: More than 150 cm.

Particle-size control section - Clay content: 30 to 35 percent.
Rock fragments: 40 to 60 percent, mainly cobbles and gravel. Lithology of fragments are volcanic rocks such as basalt or tuff.

A horizon
Value: 5 or 6 dry, 3 or 4 moist.

AB horizon
Value: 5 or 6 dry, 3 or 4 moist.
Chroma: 3 or 4 dry, 2 through 4 moist.
Texture: Gravelly loam or very gravelly loam.
Clay content: 15 to 24 percent.
Rock fragments: 20 to 45 percent.

Btk horizon
Clay content: 30 to 35 percent.
Rock fragments: 40 to 60 percent.
Identifiable secondary carbonates: Occurs as few or medium coats on bottoms of rock fragments.
Calcium carbonate equivalent: 1 to 3 percent.
Bkq horizon (when present)
Calcium carbonate equivalent: 2 to 5 percent.
Bkqm horizons
Value: 6 through 8 dry, 4 through 7 moist.
Chroma: 2 through 4, dry or moist.
Cementation class: Strongly cemented in the upper subhorizon with an indurated laminar cap, indurated throughout in the lower subhorizon.

COMPETING SERIES: There are currently no other series in this family.

GEOGRAPHIC SETTING: Cooperdraw soils are on fan remnants. These soils formed in alluvium derived from volcanic rocks. Slopes are 1 to 5 percent. Elevations range from 1,465 to 1,830 meters. The climate is semiarid and characterized by cool, moist winters and warm, dry summers. The mean annual precipitation is 250 to 300 mm, the mean annual temperature is 6 to 7 degrees C, and the frost-free period is 50 to 80 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Anawalt, Brace, Lonegrave, Fertaline, and Ninemile soils. Anawalt and Ninemile soils are clayey, shallow to lithic contacts, and have an abrupt increase in clay content. Brace soils are fine-loamy and moderately deep to duripans overlying lithic contacts. Anawalt, Brace, and Ninemile soils are on plateaus. Lonegrave soils are moderately deep to lithic contacts, have cambic horizons, and are on escarpments on plateaus. Fertaline soils are fine, have an abrupt increase in clay content, and are on fan remnants.

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

USE AND VEGETATION: Cooperdraw soils are used for livestock grazing and wildlife habitat. The historic plant community is Wyoming big sagebrush, basin big sagebrush, Thurber's needlegrass, and bluebunch wheatgrass.

DISTRIBUTION AND EXTENT: South-central Oregon. These soils are not extensive with about 4,100 acres of the series mapped to date. MLRA 23.

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

SERIES ESTABLISHED: Lake County (Northern Part), Oregon, 2006.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - The zone from the soil surface to 20 cm (A and AB horizons).
Argillic horizon - The zone from 20 to 36 cm (Btk horizon).
Identifiable secondary carbonates - The zone from 20 to 152 cm (Btk, Bkq, Bkqm1, and Bkqm2 horizons).
Duripan - The zone from 61 to 152 cm (Bkqm1 and Bkqm2 horizons).
Particle-size control section - The zone from 20 to 36 cm (Btk horizon).

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National Cooperative Soil Survey
U.S.A.