LOCATION SPIDERHOLE              OR

Established Series
Rev. CWL-JVC-JBF
06/2011

SPIDERHOLE SERIES

The Spiderhole series consists of shallow to a duripan, well drained soils that formed in loess derived from mixed rocks over residuum and colluvium derived from welded tuff or basalt. Spiderhole soils are on plateaus and hills. Slopes are 2 to 15 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, shallow Xeric Argidurids

TYPICAL PEDON: Spiderhole very gravelly loamy sand--on a west facing slope of 4 percent at an elevation of 1,470 meters--rangeland. (Colors are for dry soil unless otherwise noted.)

A1--0 to 8 cm; brown (10YR 5/3) very gravelly loamy sand, very dark grayish brown (10YR 3/2) moist; single grain; loose, nonsticky and nonplastic; few very fine and few fine roots; common fine and common medium interstitial pores; 35 percent pebbles and 10 percent cobbles; moderately alkaline (pH 8.0); abrupt smooth boundary. (5 or 8 cm thick)

A2--8 to 15 cm; light brownish gray (10YR 6/2) gravelly sandy loam, dark grayish brown (10YR 4/2) moist; weak medium subangular blocky structure parting to moderate medium granular; slightly hard, very friable, slightly sticky and slightly plastic; common very fine, common fine, and few medium roots; common fine and common medium vesicular pores; 20 percent pebbles and 5 percent cobbles; moderately alkaline (pH 8.2); abrupt smooth boundary. (8 to 15 cm thick)

Bt--15 to 25 cm; pale brown (10YR 6/3) very cobbly sandy clay loam, brown (10YR 4/3) moist; moderate medium subangular blocky structure; hard, firm, moderately sticky and moderately plastic; few very fine, few fine, and few medium roots; few very fine and few fine tubular pores; common faint and few distinct clay films on faces of peds; 20 percent pebbles and 15 percent cobbles; moderately alkaline (pH 8.4); clear smooth boundary. (10 to 18 cm thick)

Bqkm1--25 to 38 cm; light brown (7.5YR 6/3) cemented material, brown (7.5YR 4/3) moist; strong medium platy structure; extremely hard, slightly rigid; strongly cemented by secondary silica; few very fine roots in fractures; few very fine tubular pores; slightly effervescent; secondary carbonates finely disseminated throughout; strongly alkaline (pH 8.6); clear smooth boundary. (10 to 15 cm thick)

Bqkm2--38 to 48 cm; very pale brown (10YR 7/3) cemented material, brown (10YR 5/3) moist; strong thick platy structure; very rigid; indurated by secondary silica; thin laminar caps of opal on tops of peds; strongly effervescent; secondary carbonates segregated as few medium coats on bottoms of peds; strongly alkaline (pH 8.8); abrupt smooth boundary. (5 to15 cm thick)

Bqkm3--48 to 53 cm; light brownish gray (10YR 6/2) cemented material, grayish brown (10YR 5/2) moist; strong very thick platy structure; very rigid; indurated by secondary silica; thin laminar caps of opal on tops of peds; strongly effervescent; secondary carbonates segregated as common medium coats on bottoms of peds; strongly alkaline (pH 8.8); clear smooth boundary. (5 to 15 cm thick)

Bk--53 to 61 cm; pale brown (10YR 6/3) loamy coarse sand, brown (10YR 5/3) moist; massive; soft, slightly hard, nonsticky and nonplastic; strongly effervescent; secondary carbonated finely disseminated throughout; strongly alkaline (pH 9.0); abrupt smooth boundary. (0 to 30 cm thick)

R--61 cm; hard, fractured, welded ash-flow tuff.

TYPE LOCATION: Lake County, Oregon; along a jeep trail about 0.25 miles southwest of Yankee Waterhole, 3.0 miles northwest of Sand Hollow, and 3 miles southeast of Sharp Top; approximately 900 feet north and 2,350 feet east of the southwest corner of section 11, T. 32 S., R. 19 E.; USGS Sharp Top 7.5 minute topographic quadrangle; latitude 42 degrees 48 minutes 27 seconds N and longitude 120 degrees 26 minutes 46 seconds W; NAD 83.

RANGE IN CHARACTERISTICS:
Soil moisture: Usually moist in winter and spring; dry in summer and fall; aridic moisture regime that borders on xeric.
Mean annual soil temperature: 7 to 8 degrees C.
Depth to base of the argillic horizon: 25 to 50 cm.
Depth to duripan: 25 to 50 cm.
Depth to bedrock: 50 to 70 cm to a lithic contact.

Particle-size control section - Clay content: Averages 10 to 18 percent.
Rock fragments: Averages 35 to 45 percent, mainly gravel and cobbles. Lithology of fragments are welded ash-flow tuff or basalt.

A1 horizon
Value: 5 or 6 dry, 3 or 4 moist.
Chroma: 2 or 3, dry or moist.
Structure: Single grain or granular.
Reaction: Slightly alkaline or moderately alkaline.

A2 horizon
Value: 5 or 6 dry, 3 or 4 moist.
Chroma: 2 or 3 dry, 2 through 4 moist.
Texture: Gravelly sandy loam, gravelly loamy sand, very cobbly loamy sand, or very cobbly sandy loam.
Clay content: 6 to 16 percent.
Rock fragments: 25 to 45 percent.
Reaction: Slightly alkaline or moderately alkaline.

Bt horizon
Hue: 7.5YR or 10YR.
Value: 6 or 7 dry, 3 or 4 moist.
Chroma: 2 through 4, dry and moist.
Structure: Angular blocky or subangular blocky.
Texture: Cobbly sandy clay loam, very gravelly sandy clay loam, very cobbly sandy loam, or very cobbly sandy clay loam.
Clay content: 14 to 28 percent.
Rock fragments: 30 to 50 percent.
Reaction: Slightly alkaline or moderately alkaline.

Bqkm1 horizon - Hue: 7.5YR or 10YR.
Value: 6 through 8 dry, 4 or 6 moist.
Chroma: 3 or 4, dry and moist.
Cementation: Weakly to strongly cemented by secondary silica.
Identifiable secondary carbonates: Some pedons lack carbonates in easily seen segregated forms, but have finely disseminated secondary carbonates throughout horizon matrix; some pedons have carbonates segregated as few fine coats on faces of peds.

Bqkm2 and Bqkm3 horizons
Hue: 7.5YR or 10YR.
Value: 6 through 8 dry, 5 through 7 moist.
Chroma: 2 or 3, dry and moist.
Cementation: Very strongly cemented or indurated by secondary silica.
Identifiable secondary carbonates: Occurs as few or common fine or medium coats on faces of peds.

Bk horizon
Hue: 7.5YR or 10YR.
Value: 6 or 7 dry, 5 or 6 moist.
Reaction: Strongly alkaline or very strongly alkaline (up to pH 9.6).
Identifiable secondary carbonates: Some pedons lack carbonates in easily seen segregated forms, but have finely disseminated secondary carbonates throughout horizon matrix.
Calcium carbonate equivalent: 3 to 5 percent.

COMPETING SERIES: This is the Simpark series. Simpark soils average 18 to 27 percent clay in the particle-size control section and do not have upper subhorizons of the duripan which are weakly to strongly cemented.

GEOGRAPHIC SETTING: Spiderhole soils are on plateaus and hills. These soils formed in loess derived from mixed rocks over residuum and colluvium derived from welded tuff or basalt. Slopes are 2 to 15 percent. Elevations range from 1,385 to 1,710 meters. The climate is semiarid with cold, 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 70 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Brace, Snakepit, and Wiskan soils. Brace soils are fine-loamy and moderately deep to thin duripans over lithic contacts. Snakepit soils are sandy, moderately deep to non-indurated duripans, have mollic epipedons, and occur on adjacent depressions. Wiskan soils are moderately deep to lithic contacts and occur on adjacent hills and escarpments.

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

USE AND VEGETATION: Spiderhole soils are used for livestock grazing. The present vegetation varies with surface texture phase. The loamy sand phase supports basin big sagebrush and needleandthread. The sandy loam phase supports Wyoming big sagebrush, Thurber's needlegrass, Indian ricegrass, and bluebunch wheatgrass.

DISTRIBUTION AND EXTENT: South-central Oregon. These soils are not extensive with about 6,200 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. The name is coined.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - The zone from the soil surface to 15 cm (A1 and A2 horizons).
Argillic horizon - The zone from 15 to 25 cm (Bt horizon).
Duripan - The zone from 25 to 53 cm (Bqkm1, Bqkm2, and Bqkm3 horizons).
Lithic contact - The boundary at 61 cm to underlying hard bedrock (R layer).
Particle-size control section - The zone from the soil surface to 25 cm (A1, A2, and Bt horizons).

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National Cooperative Soil Survey
U.S.A.