LOCATION POTHOLE OR

Tentative Series
IRD. SCW/KMS
04/2013

POTHOLE SERIES

The Pothole series consists of very deep, poorly drained soils formed in glaciofluvial material with an influence of ash in the surface horizons. They are found in kettles surrounded by glaciofluvial deposits on fan remnants and outwash plains. Slopes are 0 to 2 percent. The mean annual precipitation is 17 inches (430 millimeters), and the mean annual temperature is 6 degrees C.

TAXONOMIC CLASS: Fine, smectitic Aquic Palecryolls

TYPICAL PEDON: Pothole ashy silty clay - livestock grazing, on a 1 percent slope at an elevation of 1,435.0 meters. (When described on October 12, 2010, the surface was dry to 64 centimeters, but moist within the clay layer. Colors are for moist soils unless otherwise noted.)

A1--0 to 10 inches (0 to 25 cm); very dark brown (10YR 2/2) ashy silty clay, dark grayish brown (10YR 4/2) dry; moderate fine and medium subangular blocky structure; hard, firm, moderately sticky and moderately plastic; few fine and many very fine roots; few fine and common very fine tubular pores; slightly acid (pH 6.1); abrupt smooth boundary.

A2--10 to 20 inches (25 to 51 cm); brown (10YR 4/3) ashy silty clay loam, pale brown (10YR 6/3) dry; moderate medium subangular blocky structure; slightly hard, friable, moderately sticky and slightly plastic; few fine and common very fine roots; few fine and very fine tubular pores; few fine iron depletions along root channels; slightly acid (pH 6.5); abrupt smooth boundary. (Combined thickness of the A horizon is 45 to 64 centimeters.)

E--20 to 25 inches (51 to 64 cm); light gray (10YR 7/1) ashy silty clay loam, white (10YR 8/1) dry; moderate medium subangular blocky structure; hard, firm, moderately sticky and moderately sticky; few very fine roots; few very fine tubular pores; neutral (pH 6.7); abrupt smooth boundary. (1 to 15 centimeters thick)

2Bt1--25 to 40 inches (64 to 102 cm); very dark grayish brown (10YR 3/2) clay, dark grayish brown (10YR 4/2) dry; moderate medium and coarse prismatic structure; very hard, very firm, very sticky and very plastic; continuous prominent clay films on ped faces; few very fine tubular pores; neutral (pH 6.8); gradual wavy boundary.

2Bt2--40 to 48 inches (102 to 122 cm); dark brown (10YR 3/3) clay, brown (10YR 4/3) dry; moderate medium and coarse prismatic structure; very hard, very firm, very sticky and very plastic; continuous distinct clay films on ped faces; neutral (pH 6.9).

TYPE LOCATION: Grant County, Oregon, located in Bear Valley about 3.5 miles northwest of the town of Seneca.
Longitude: -119.00530
Latitude: 44.191814
Datum: WGS84

RANGE IN CHARACTERISTICS:

Mean annual soil temperature: 6 to 8 degrees C
Mean annual summer soil temperature: less than 13 degrees C
Depth to redoximorphic depletions: 25 cm
Thickness of mollic epipedon: 25 to 50 cm

Volcanic ash influenced layers:
Thickness: 18 to 71 cm
Volcanic glass content in the 0.02 to 2.0 mm fraction: 20 to 40 percent
Ammonium oxalate extractable Al plus 1/2 Fe: less than 0.40

Particle Size Control Section:
Clay Content: 50 to 60 percent

A horizons
Value: 2 or 3 moist, 4 or 5 dry
Chroma: 2 or 3, moist or dry
Fine-earth texture: ashy silty clay loam or ashy silty clay
Clay content: 27 to 45 percent

E horizon
Value: 6 or 7 moist, 7 or 8 dry
Chroma: 1 or 2, moist or dry
Fine-earth texture: ashy silty clay loam or ashy silt loam
Clay content: 20 to 30 percent

2Bt horizons
Value: 3 or 4 moist, 4 or 5 dry
Chroma: 2 or 3, moist or dry
Clay content: 50 to 60 percent

COMPETING SERIES: There are no competing series.

GEOGRAPHIC SETTING: Pothole soils occur in kettles on fan remnants and outwash plains and have slopes of 0 to 2 percent. They formed in glaciofluvial material with an influence of ash in the surface. Elevations are 1,370 to 1,490 meters. The climate is characterized by cold, wet winters and cool, dry summers. The mean annual precipitation is 355 to 510 millimeters and the mean temperature is 6 to 8 degrees C. The frost free period is 30 to 80 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Choptie, Daxty, Herberger (T), Keerins (T), Luckycreek, Silvies, and Sylvaille (T) series. Choptie soils are shallow to tuffaceous sandstone bedrock and are on isolated fan remnants. Daxty soils are loamy-skeletal, are moderately deep to tuffaceous sandstone, and are on low hills. Herberger soils are in the fine family, are moderately deep to a densic layer, and are found on fan remnants. Keerins soils are loamy-skeletal, shallow to shale bedrock, and are on rolling hills. Luckycreek soils are fine-loamy and are on terraces. Silvies soils are in the fine family and are on floodplains. Sylvaille soils are loamy, shallow to densic layer, and are found on fan remnants with Pothole soils.

DRAINAGE AND PERMEABILITY: Poorly drained with epi-saturation; very slow permeability.

USE AND VEGETATION: The soils are used for livestock grazing and wildlife habitat. The potential native vegetation is tufted hairgrass, sedges, and rushes. Ecological site is Cold Meadow (R010XY002OR). Wherever silver sage occurs is considered a different ecological site (Cold Moist Meadow R010XY032OR) and there will also be areas where Cold Wet Meadow (10XY001) occurs but the non-wet meadow ecosite will predominant.

DISTRIBUTION AND EXTENT: Mountain valley of east-central Oregon, MLRA B-10. This series is of small extent.

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

SERIES PROPOSED: Grant County, Oregon, 2011.

REMARKS: Diagnostic horizons and features recognized in this pedon are

Mollic epipedon - 0 to 25 cm (A1 horizon)

Albic horizon - 51 to 64 cm (E horizon)

Argillic horizon - 64 to 122 cm - (2Bt1 and 2Bt2 horizons)

Aquic conditions - perched water from 25 to 64 cm, April through June (A2 and E horizons)

Horizons containing enough volcanic ash to meet the vitrandic criteria - 0 to 64 cm (A1, A2, and E horizons)

Particle size control section: 64 to 114 cm (2Bt1 horizon and part of the 2Bt2 horizon)

Cryic soil temperature regime

Xeric soil moisture regime, bordering on aquic

ADDITIONAL DATA: The upper four horizons of this pedon were sampled in fall of 2010. The soil series name used at the time of sampling was Railway.

Lap Pedon Number: 11NO358
User Pedon ID: S10OR023001

National Cooperative Soil Survey
U.S.A.