LOCATION PICTUREROCK             OR

Established Series
Rev. MPK-JVC-JBF
05/2011

PICTUREROCK SERIES

The Picturerock series consists of very deep, moderately well drained soils that formed in lacustrine deposits derived from pumiceous volcanic ash. Picturerock soils are on lake terraces. Slopes are 1 to 3 percent. The mean annual precipitation is about 230 mm and the mean annual temperature is about 7 degrees C.

TAXONOMIC CLASS: Ashy, glassy, frigid Vitritorrandic Haploxerolls

TYPICAL PEDON: Picturerock ashy loam--on a one percent slope at an elevation of 1,314 meters--rangeland. (Colors are for dry soil unless otherwise noted. When described on October 15, 1998, the soil was dry throughout.)

Ak--0 to 8 cm; grayish brown (2.5Y 5/2) ashy loam, very dark grayish brown (10YR 3/2) moist; moderate very thin platy structure; soft, very friable, slightly sticky and slightly plastic; many very fine roots; few very fine tubular pores; strongly effervescent; secondary carbonates segregated as few fine irregularly shaped coats on faces of peds; moderately alkaline (pH 8.0); clear smooth boundary. (8 to 30 cm thick)

Bk1--8 to 20 cm; grayish brown (2.5Y 5/2) ashy sandy clay loam, very dark grayish brown (10YR 3/2) moist; moderate coarse prismatic structure; slightly hard, firm, moderately sticky and slightly plastic; common very fine roots; common very fine and common fine tubular pores; strongly effervescent; secondary carbonates segregated as few fine irregularly shaped coats on faces of peds and in filaments; strongly alkaline (pH 9.0); clear smooth boundary. (8 to 15 cm thick)

Bk2--20 to 28 cm; grayish brown (2.5Y 5/2) ashy sandy loam, very dark grayish brown (10YR 3/2) moist; weak fine subangular blocky structure; soft, very friable, slightly sticky and nonplastic; many very fine and common fine roots; common very fine and common fine tubular pores; 20 percent krotovinas; strongly effervescent; secondary carbonates segregated as few fine irregularly shaped coats on faces of peds; strongly alkaline (pH 8.8); clear smooth boundary. (5 to 13 cm thick)

Bk3--28 to 46 cm; grayish brown (2.5Y 5/2) ashy sandy loam, dark grayish brown (2.5Y 4/2) moist; weak medium platy structure; slightly hard, friable, slightly sticky and nonplastic; common very fine and common fine roots, common very fine through medium tubular pores; strongly effervescent; secondary carbonates segregated as few fine irregularly shaped coats on faces of peds; strongly alkaline (pH 8.6); gradual smooth boundary.

Bk4--46 to 71 cm; light brownish gray (2.5Y 6/2) ashy sandy loam, dark grayish brown (2.5Y 4/2) moist; weak very thick platy structure parting to moderate coarse subangular blocky; slightly hard, friable, slightly sticky and nonplastic; common very fine and common fine roots, common very fine through medium tubular pores; strongly effervescent; secondary carbonates segregated as few fine irregularly shaped coats on faces of peds; strongly alkaline (pH 8.6); gradual smooth boundary.

Bk5--71 to 84 cm; light brownish gray (2.5Y 6/2) ashy loam, dark grayish brown (2.5Y 4/2) moist; weak medium prismatic structure; hard, firm, moderately sticky and slightly plastic; common very fine and common fine roots, common very fine through medium tubular pores; strongly effervescent; secondary carbonates segregated as few fine irregularly shaped coats on faces of peds; strongly alkaline (pH 8.6); gradual smooth boundary. (Combined thickness of lower Bk horizons is 25 to 76 cm)

2Ck1--84 to 122 cm; brown (10YR 5/3) very paragravelly ashy loam, brown (10YR 4/3) and brown (10YR 5/3) moist; strong very fine angular rock structure; very hard, very firm, slightly sticky and slightly plastic; common very fine and few fine roots; many very fine interstitial pores; few krotovinas; about 50 percent paragravel; strongly effervescent; secondary carbonates segregated as common white filaments on pararock fragments and within the matrix; few fine faint pink (7.5YR 7/4) relict masses of iron accumulation; strongly alkaline (pH 8.6),gradual smooth boundary. (25 to 76 cm thick)

2Ck2--122 to 152 cm; grayish brown (2.5Y 5/2) very paragravelly ashy sandy clay loam, brown (10YR 4/3) and brown (10YR 5/3) moist; strong very fine angular rock structure; hard, very firm, slightly sticky and slightly plastic; common very fine roots; many very fine interstitial pores; about 50 percent paragravel; strongly effervescent; secondary carbonates segregated as common white filaments on pararock fragments and within the matrix; strongly alkaline (pH 8.6).

TYPE LOCATION: Lake County, Oregon; between Silver Lake and State Highway 31; approximately 1,000 feet north and 1,400 feet west of the southeast corner of section 32, T. 28 S., R. 16 E.; USGS Egli Rim 7.5 minute topographic quadrangle; latitude 43 degrees 5 minutes 45.9 seconds N and longitude 120 degrees 50 minutes 38.6 seconds W; NAD 83.

RANGE IN CHARACTERISTICS:
Soil moisture: Usually moist in the moisture control section 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.
Mollic epipedon thickness: 18 to 28 cm; includes the Bk1 and Bk2 horizons in some pedons.
Depth to base of cambic horizon: 64 to 90 cm.
Reaction: Moderately alkaline or strongly alkaline.

Particle-size control section - Clay content: 18 to 27 percent;
Volcanic glass content: 75 to 100 percent in coarse silt through fine sand fractions.

Ak horizon
Hue: 10YR or 2.5Y.
Value: 4 or 5 dry, 2 or 3 moist.
Chroma: 1 through 3, dry or moist.
Organic matter content: 1 to 3 percent.
Effervescence: Slightly effervescent or strongly effervescent.
Identifiable secondary carbonates: Occurs as few fine filaments or coats on faces of peds.
Calcium carbonate equivalent: 1 to 3 percent.

Bk horizons
Hue: 10YR or 2.5Y.
Value: 5 through 7 dry, 3 or 4 moist.
Chroma: 1 through 3, dry or moist.
Texture: Ashy sandy loam, ashy loam, or ashy sandy clay loam.
Clay content: 12 to 30 percent.
Organic matter content: 1 to 3 percent in horizons within the mollic epipedon.
Effervescence: Slightly effervescent or strongly effervescent.
Identifiable secondary carbonates: Occurs as few fine filaments or coats on faces of peds.
Calcium carbonate equivalent: 1 to 3 percent.

2Ck horizons
Value: 5 or 6 dry, 4 or 5 moist.
Chroma: 2 through 4, dry or moist.
Texture: Very paragravelly loam or very paragravelly sandy clay loam.
Clay content: 18 to 27 percent.
Pararock fragments: 35 to 60 percent paragravel which are soft, consolidated lacustrine deposits.
Effervescence: Slightly effervescent or strongly effervescent.
Identifiable secondary carbonates: Occurs as few filaments in the matrix and coats on pararock fragments.
Calcium carbonate equivalent: 1 to 3 percent.

COMPETING SERIES: These are the Boltz, Bonnick, Borobey, Emamount, Embal, Frentera, Gardone, Oatmanflat, Stookmoor, Tuffcabin, and Wegert series.

Boltz soils are moderately deep to paralithic contacts. Bonnick and Gardone soils do not have cambic horizons or horizons with identifiable secondary carbonates and have ashy sandy textures in the particle-size control section. Borobey soils have firm, brittle horizons within 100 cm and do not have horizons with identifiable secondary carbonates. Emamount soils do not have cambic horizons or horizons with identifiable secondary carbonates. Embal soils have mollic epipedons 50 to 90 cm thick and have irregular decrease in organic carbon with depth. Frentera, Stookmoor, and Wegert soils are moderately deep to lithic contacts. Oatmanflat and Tuffcabin soils have buried argillic horizons within 100 cm and buried duripans within 150 cm of the soil surface.

GEOGRAPHIC SETTING: Picturerock soils are on lake terraces. These soils formed in lacustrine deposits derived from pumiceous volcanic ash. Slopes are 1 to 3 percent. Elevations range from 1,310 to 1,345 meters. The climate is semiarid and characterized by cold, moist winters and warm, dry summers. The mean annual precipitation is 200 to 250 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 Bridgewell and Bunyard soils. Bridgewell soils have endosaturation within 75 cm of the soil surface. Bunyard soils have ochric epipedons and natric horizons.

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Moderately well drained; negligible surface runoff; moderately high saturated hydraulic conductivity. These soils are susceptible to rare ponding for very long duration from January through June with water up to 30 cm deep.

USE AND VEGETATION: Picturerock soils are used for livestock grazing and wildlife habitat. The vegetation is mainly creeping wildrye and annuals.

DISTRIBUTION AND EXTENT: South-central Oregon. These soils are not extensive with about 1,400 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:
Mollic epipedon - The zone from the soil surface to 28 cm (Ak, Bk1, and Bk2 horizons).
Cambic horizon - The zone from 28 to 84 cm (Bk3, Bk4, and Bk5 horizons).
Vitrandic intergrade feature - The zone from the soil surface to 76 cm (Ak, Bk1, Bk2, Bk3, and Bk4 horizons and part of the Bk5 horizon).
Identifiable secondary carbonates - The zone from the soil surface to 152 cm (all horizons).
Particle-size control section and ashy substitute class with glassy mineralogy - The zone from 25 to 100 cm (Bk3, Bk4, and Bk5 horizons and parts of the Bk2 and 2Ck1 horizons).

ADDITIONAL DATA: Volcanic glass in the Bk4 and 2Ck1 horizons determined locally by optical grain counts using a polarizing petrographic microscope.

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National Cooperative Soil Survey
U.S.A.