LOCATION GIBBS                   WA

Established Series
Rev. SMM/EMM/RWL
06/2016

GIBBS SERIES

Landscape--Columbia basalt plateau
Landform--plateaus
Slope--0 to 15 percent
Parent material--colluvium and residuum derived from basalt with minor amounts of glaciofluvial deposits, loess, and volcanic ash in upper part
Mean annual precipitation--about 560 mm
Mean annual air temperature--about 8 degrees C
Depth class--moderately deep
Drainage class--well drained
Soil moisture regime--xeric
Soil temperature regime--mesic
Soil moisture subclass--typic

TAXONOMIC CLASS: Fine-loamy, isotic, mesic Vitrandic Argixerolls

TYPICAL PEDON: Gibbs ashy silt loam in an area with a canopy of ponderosa pine, on an east-facing, 4-percent slope at an elevation of 760 m (When described on October 4, 2000, the soil was dry throughout. All textures are apparent field textures.)

Oi--0 to 1 cm; slightly decomposed needles, twigs, and leaves

Oe--1 to 3 cm; moderately decomposed organic matter mixed with 1980 Mount St. Helens ash

A--3 to 13 cm; ashy silt loam, brown (10YR 4/3) dry, very dark grayish brown (10YR 3/2) moist; weak fine and medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; common very fine and fine and few medium roots; many very fine and fine tubular pores and many fine irregular pores; neutral (pH 6.8); clear wavy boundary

AB--13 to 33 cm; ashy silt loam, dark grayish brown (10YR 4/2) dry, very dark grayish brown (10YR 3/2) moist; moderate coarse subangular blocky structure; hard, firm, slightly sticky and slightly plastic; common very fine and fine and few medium roots; common very fine and fine tubular pores; neutral (pH 7.0); clear wavy boundary

Bt1--33 to 51 cm; silty clay loam, brown (10YR 5/3) dry, dark brown (10YR 3/3) moist; moderate coarse subangular blocky structure; very hard, firm, slightly sticky and moderately plastic; common very fine, fine, and medium roots; common very fine and few fine tubular pores; 10 percent faint clay films on all faces of peds; 2 percent subrounded basalt gravel; slightly acid (pH 6.2); gradual wavy boundary

Bt2--51 to 79 cm; silty clay loam, yellowish brown (10YR 5/4) dry, dark yellowish brown (10YR 3/4) moist; moderate medium and coarse subangular blocky structure; very hard, firm, slightly sticky and moderately plastic; few very fine, fine, and medium roots throughout; common very fine and few fine tubular pores; 25 percent faint clay films on all faces of peds; 5 percent subrounded basalt gravel; neutral (pH 6.6); clear wavy boundary

BCt--79 to 89 cm; very gravelly silt loam, yellowish brown (10YR 5/4) dry, dark yellowish brown (10YR 3/4) moist; weak medium subangular blocky structure; very hard, very firm, slightly sticky and moderately plastic; few very fine, fine, and medium roots; few very fine and fine tubular pores; 20 percent faint clay films on all faces of peds; 30 percent subangular basalt gravel and 20 percent angular basalt cobbles; neutral (pH 6.7); abrupt wavy boundary

2R--89 cm; indurated basalt; fractures at intervals of 10 to 45 cm; weathering rinds about 3 cm thick in fractures

TYPE LOCATION: Spokane County, Washington, about 2 km southwest of Mica; about 235 m west and 600 m south of the northeast corner of section 28, T. 24 N., R. 44 E.; Freeman, Washington, U.S. Geological Survey topographic quadrangle; latitude 47.5456944, longitude -117.2417500, datum WGS 84 (coordinates measured with GPS)

RANGE IN CHARACTERISTICS:
The depth to diagnostic horizons and other features are measured from the top of the first mineral layer.

Mean annual soil temperature--9 to 11 degrees C
Moisture control section--dry 60 to 90 days after summer solstice (July through September); moist in October through June
Depth to basalt--50 to 100 cm
Thickness of mollic epipedon--25 to 50 cm
Content of clay in particle-size control section--18 to 30 percent
Reaction--6.1 to 7.3
Estimated base saturation--less than 75 percent, by sum of cations, in one horizon or more between depths of 25 and 75 cm
Thickness of volcanic ash influence--20 to 35 cm

Estimated properties of layers influenced by volcanic ash
*Content of volcanic glass in 0.02- to 2-mm fraction--5 to 20 percent
*Acid oxalate Al plus 1/2 Fe--0.4 to 1.0 percent
*Moist bulk density--1.15 to 1.35 g/cm3

A horizon
*Value--4 or 5 dry, 2 or 3 moist
*Chroma--2 or 3 dry or moist
*Content of gravel--0 to 5 percent
*Thickness--5 to 15 cm

AB horizon
*Value--4 or 5 dry, 2 or 3 moist
*Chroma--2 or 3 dry or moist
*Texture--ashy silt loam, ashy loam
*Content of gravel--0 to 5 percent
*Thickness--13 to 20 cm

Bt horizon
*Value--5 or 6 dry, 3 or 4 moist
*Chroma--3 to 6 dry or moist
*Texture--silt loam, loam, silty clay loam
*Content of clay--18 to 30 percent
*Content of gravel--0 to 10 percent
*Combined thickness--40 to 60 cm

BCt horizon, or C horizon (where present)
Hue--10YR, 7.5YR
Value--5 or 6 dry, 3 or 4 moist
Chroma--4 to 6 dry or moist
Texture--silt loam, loam, silty clay loam
Total content of rock fragments--35 to 75 percent
Content of gravel--30 to 60 percent
Content of cobbles--0 to 25 percent
Thickness--5 to 10 cm

COMPETING SERIES:
Dragoon--50 to 100 cm deep to paralithic contact
Glenrose--100 to 150 cm to paralithic contact

GEOGRAPHIC SETTING:
Elevation--580 to 790 m
Climate--warm, relatively dry summers; cool, moist winters
Mean annual precipitation--460 to 635 mm
Mean annual air temperature--8 to 10 degrees C
Frost-free season--100 to 130 days

GEOGRAPHICALLY ASSOCIATED SOILS:
Bobbitt--loamy-skeletal; on basalt plains
Driscoll--fine; on loess hills
Lacy--shallow to basalt; loamy-skeletal; on basalt ridges and terraces
Uhlig--coarse-loamy; on basalt plateaus

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
Drainage class--well drained
Saturated hydraulic conductivity (Ksat)--moderately high

USE AND VEGETATION:
Use--dominantly homesite development, livestock grazing, and crop production; some areas of wildlife habitat and watershed
Common crops--small grain, hay, pasture
Potential natural vegetation--ponderosa pine, Saskatoon serviceberry, common snowberry, Idaho fescue, arrowleaf balsamroot, common yarrow, lupine

DISTRIBUTION AND EXTENT: Eastern Washington; MLRA 9; small extent

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon

SERIES ESTABLISHED: Spokane County, Washington; 2012

REMARKS:
Diagnostic horizons and other features in this pedon
*Mollic epipedon--zone from 3 to 50 cm
*Argillic horizon--zone from 33 to 79 cm
*Vitrandic feature--zone from 3 to 33 cm
*Ultic feature--zone from 28 to 79 cm; less than 75 percent base saturation, by sum of cations, in one horizon or more
*Particle-size control section--zone from 33 to 79 cm

This series is correlated to the PIPO/SYAL habitat type.

The Gibbs series should be further investigated to determine typical mineralogy (isotic versus mixed).

6/2016--This official series description (OSD) was updated as part of the final correlation of the Spokane County, Washington, soil survey. The formatting was updated according to SSR1 Technical Note 11--Content and Format of Official Series Descriptions (revised 12/2015).

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National Cooperative Soil Survey
U.S.A.