LOCATION COCOLALLA               WA

Established Series
Rev. NCD/KMS/CSM/SHB
06/2016

COCOLALLA SERIES

Landscape--Columbia basalt plateau
Landform--drainageways, depressions
Slope--0 to 3 percent
Parent material--alluvium derived from volcanic ash mixed with minor amounts of loess in upper part
Mean annual precipitation--about 410 mm
Mean annual air temperature--about 8 degrees C
Depth class--deep, very deep
Drainage class--poorly drained
Soil moisture regime--aquic
Soil temperature regime--mesic
Soil moisture subclass--typic

TAXONOMIC CLASS: Ashy, glassy, mesic Aquandic Endoaquolls

TYPICAL PEDON: Cocolalla ashy silt loam in an area of native pasture, on a 0-percent, concave slope at an elevation of 710 m (When described on September 28, 1999, the soil was moist to a depth of about 140 cm and wet below.)

A1--0 to 28 cm; ashy silt loam, dark gray (10YR 4/1) dry, black (10YR 2/1) moist; moderate medium subangular blocky structure; friable, slightly hard, nonsticky and moderately plastic; common very fine and fine roots throughout; common very fine irregular pores; moderately acid (pH 5.8); abrupt smooth boundary

A2--28 to 71 cm; ashy silt loam, gray (2.5Y 6/1) dry, black (10YR 2/1) moist; moderate medium subangular blocky structure; friable, slightly hard, slightly sticky and slightly plastic; common very fine and fine roots throughout; common very fine irregular pores; 4 percent fine masses of oxidized iron-manganese that are dark yellowish brown (10YR 3/4) moist; neutral (pH 6.9); abrupt wavy boundary

Cg1--71 to 94 cm; ashy silt loam, white (10YR 8/1) dry, light brownish gray (10YR 6/2) moist; massive; very friable, soft, nonsticky and nonplastic; common very fine and fine roots throughout; common very fine irregular pores; neutral (pH 7.2); clear wavy boundary

Cg2--94 to 109 cm; ashy silt loam, white (10YR 8/1) dry, dark grayish brown (2.5Y 4/2) moist; massive; very friable, soft, nonsticky and nonplastic; common very fine and fine roots throughout; common very fine irregular pores; 5 percent fine masses of oxidized iron-manganese that are light olive brown (2.5Y 5/6) moist; neutral (pH 7.1); clear wavy boundary

Ab--109 to 137 cm; ashy silt loam, light gray (10YR 7/1) dry, very dark grayish brown (10YR 3/2) moist; weak medium subangular blocky structure; friable, slightly hard, slightly sticky and slightly plastic; common very fine and fine roots throughout; common very fine irregular pores; 5 percent medium masses of oxidized iron-manganese that are dark yellowish brown (10YR 3/6) moist; neutral (pH 7.0); clear wavy boundary

Cgb--137 to 150 cm; ashy silt loam, pale yellow (2.5Y 8/2) dry, light brownish gray (2.5Y 6/2) moist; massive; friable, slightly hard, slightly sticky and slightly plastic; common very fine and fine roots throughout; common very fine irregular pores; 5 percent medium masses of oxidized iron-manganese that are light yellowish brown (2.5Y 6/4) moist and 5 percent iron depletions that are greenish gray (10G 6/1) moist; neutral (pH 6.8)

TYPE LOCATION: Spokane County, Washington, about 470 m north and 190 m east of the southwest corner of section 1, T. 26 N., R. 40 E.; Four Mound Prairie
U.S. Geological Survey topographic quadrangle; latitude 47.7779732, longitude
-117.7096405, datum WGS 84 (coordinates measured with GPS)

RANGE IN CHARACTERISTICS:
Mean annual soil temperature--8 to 10 degrees C
Thickness of mollic epipedon--25 to 50 cm
Depth to apparent water table--uppermost limit in January through December
Depth to redoximorphic concentrations--more than 2 percent at a depth of 25 to 50 cm; not visible in all pedons
Depth to aquic conditions--25 to 50 cm
Depth to bedrock--more than 100 cm, but commonly more than 150 cm
Content of volcanic glass in particle-size control section--more than 60 percent
Thickness of volcanic ash influence--100 to 150 cm

Estimated properties of layers influenced by volcanic ash
*Content of volcanic glass in 0.02- to 2-mm fraction--more than 60 percent
*Acid oxalate Al plus 1/2 Fe--less than 0.4 percent
*Moist bulk density--0.90 to 1.25 g/cm3

A horizon
*Hue--10YR, 2.5Y
*Value--3 to 6 dry, 2 or 3 moist
*Chroma--1 or 2 dry or moist
*Texture--ashy silty clay loam, ashy silt loam
*Reaction--5.6 to 7.3

Cg horizon
*Hue--10YR, 5Y, 2.5Y
*Value--5 to 8 dry, 3 to 6 moist
*Chroma--1 or 2 moist or dry
*Texture--ashy silt, ashy silt loam, ashy very fine sandy loam; silty clay loam or clay loam in lower part of some pedons in areas where buried horizons are not present
*Content of gravel--0 to 10 percent
*Thickness of pumicite or diatomite layers--0 to 40 cm
*Reaction--6.6 to 7.8

Ab horizon (where present)
*Hue--10YR, 2.5Y
*Value--5 to 7 dry, 2 to 4 moist
*Chroma--1 to 3 moist or dry
*Texture--ashy silt, ashy silt loam, ashy very fine sandy loam
*Content of gravel--0 to 10 percent
*Reaction--6.6 to 7.8

Cgb horizon (where present)
*Hue--10YR, 2.5Y
*Value-- 6 to 8 dry, 4 to 6 moist
*Chroma--1 or 2 moist or dry
*Texture--ashy silt, ashy silt loam, ashy very fine sandy loam, silty clay loam
*Content of gravel--0 to 10 percent
*Reaction--6.6 to 7.8

AB and BA horizons are in some pedons.

COMPETING SERIES:
Waterflat-- stratified loam to coarse sand 2BCk horizon; Bk horizon with secondary carbonates at a depth of 75 cm
Wetvit--gravelly 2C horizon

GEOGRAPHIC SETTING:
Elevation--520 to 690 m
Climate--relatively dry summers; moist, cold winters
Mean annual precipitation--360 to 510 mm
Mean January air temperature--about -2 degrees C
Mean July air temperature--19 degrees C
Mean annual air temperature--7 to 10 degrees C
Frost-free period--90 to 140 days

GEOGRAPHICALLY ASSOCIATED SOILS:
Hardesty--on low terraces; contemporary redoximorphic concentrations between depths of 50 and 100 cm
Northstar--on basalt plateaus; moderately deep to lithic contact
Rockly--on basalt plateaus; lithic contact within a depth of 50 cm

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
Drainage class--poorly drained
Saturated hydraulic conductivity (Ksat)--moderately high
Ponding--occasional or frequent periods
Flooding--long or very long duration

USE AND VEGETATION:
Use--crop production, livestock grazing, wildlife habitat
Common crops--small grain, grasses, legumes
Native vegetation--tufted hairgrass, redtop sedge, rushes, buttercup, cowparsnip

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

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

SERIES ESTABLISHED: Bonner County, Idaho; 1935

REMARKS:
Diagnostic horizons and other features in this pedon
*Mollic epipedon--zone from surface to a depth of 28 cm
*Aquic feature--zone from 28 to 150 cm
*Particle-size control section--zone from 25 to 100 cm

6/2008--The type location was moved to present location to better reflect the modal concept.

6/2016--This official series description (OSD) was updated as part of the final correlation of the Spokane County, Washington, soil survey. The ash in the Cocolalla soils is from the eruption of Mount Mazama. The content of ash is very high, but because of the sustained water table it has not weathered enough to meet the acid oxalate Al plus one-half Fe criteria for andic soil properties. Diatomaceous earth may be in some pedons. The formatting of the OSD was updated according to SSR1 Technical Note 11--Content and Format of Official Series Descriptions (revised 12/2015).

ADDITIONAL DATA:
Laboratory data--Kellogg Soil Survey Laboratory, Lincoln, Nebraska, pedon numbers S57 Wash-32-3 (1-8) and S57 Wash-32-4 (1-7)

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National Cooperative Soil Survey
U.S.A.