LOCATION LOGANVALLEY ORTentative Series
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, frigid Vitrandic Argixerolls
TYPICAL PEDON: Loganvalley gravelly ashy loam - rangeland. (When described on September 9, 2001, the upper 7 inches was slightly moist and was dry below. Colors are for moist soil unless otherwise noted.)
A1--0 to 2 inches; very dark grayish brown (10YR 3/2) gravelly ashy loam, brown (10YR 5/3) dry; weak fine and very fine granular structure; soft, very friable, slightly sticky and nonplastic; many very fine and fine roots; many very fine interstitial pores; 15 percent gravel; neutral (pH 7.0); clear smooth boundary.
A2--2 to 8 inches; very dark grayish brown (10YR 3/2) gravelly ashy loam, brown (10YR 5/3) dry; moderate fine subangular blocky structure; soft, very friable, slightly sticky and slightly plastic; many very fine and fine roots; few very fine tubular pores; 20 percent gravel; neutral (pH 7.2); clear smooth boundary. (The combined thickness of the A horizon is 7 to 20 inches thick)
2Bt1--8 to 13 inches; dark brown (10YR 3/3) very cobbly clay loam, yellowish brown (10YR 5/4) dry; weak fine subangular blocky structure; hard, friable, moderately sticky and moderately plastic; common very fine and common fine roots; roots form mats around rock fragments; common very fine tubular pores; common discontinuous clay films on faces of peds; 25 percent gravel and 25 percent cobbles; slightly alkaline (pH 7.5); clear wavy boundary.
2Bt2--13 to 23 inches; dark grayish brown (10YR 4/2) extremely gravelly clay loam, yellowish brown (10YR 5/4) dry; massive; hard, very friable, very sticky and very plastic; common very fine and fine roots; roots form mats around rock fragments; many very fine interstitial pores; common thin discontinuous clay films on faces of peds; 60 percent gravel and 10 percent cobbles; slightly alkaline (pH 7.5); clear wavy boundary. (The combined thickness of Bt horizons is 10 to 20 inches thick)
2Bq--23 to 60 inches; variegated colors but dominantly brown (10YR 4/3) extremely gravelly sandy clay loam, pale brown (10YR 6/3) dry; massive; loose, moderately sticky and moderately plastic; few fine roots; many very fine interstitial pores; silica coatings on the bottom of rock fragments; 50 percent gravel and 20 percent cobbles; slightly alkaline (pH 7.5).
TYPE LOCATION: Grant County, Oregon; in Logan Valley, 21 miles east of Seneca and 24 miles southeast of John Day, 600 feet west and 2800 feet north of the southeast corner Section 23, T. 16 S., R. 33 E. (Logan Valley East, Oregon USGS 7.5 minute quadrangle, 44 degrees 10 minutes 10 seconds north latitude, 118 degrees 36 minutes 5 seconds west longitude)
RANGE IN CHARACTERISTICS: These soils are usually moist, but are dry in the moisture control section for 60 to 90 days following the summer solstice. The mean annual soil temperature is 43 to 47 degrees F. Depth to bedrock is more than 60 inches. The mollic epipedon is 10 to 20 inches thick and typically includes part of the 2Bt horizon. The soil is neutral or slightly alkaline throughout.
The A horizon has value of 2 or 3 moist, 4 or 5 dry, and chroma of 2 or 3 moist and dry. It is loam with 15 to 27 percent clay. It contains 5 to 20 percent gravel and 0 to 10 percent cobbles. It is estimated to have 10 to 30 percent glass, acid oxalate extractable aluminum plus one-half the iron is 0.2 to 0.4.
The 2Bt horizon has hue of 10YR or 7.5 YR, value of 3 or 4 moist, 4 or 5 dry, and chroma of 2 to 4 moist and dry. It is clay loam or loam with 20 to 35 percent clay. It averages 35 to 70 percent rock fragments with 30 to 60 percent gravel, 5 to 30 percent cobbles, and 0 to 5 percent stones.
The 2Bq horizon has dominant value of 3 or 4 moist, 4 to 6 dry, and chroma of 3 or 4 moist and dry. It may be variegated. It is sandy clay loam, clay loam, sandy clay, or clay with 20 to 45 percent clay. It averages 40 to 75 percent rock fragments with 30 to 60 percent gravel, 15 to 30 percent cobbles, and 0 to 10 percent stones. It has silica coatings on the undersides of rock fragments.
COMPETING SERIES: These are the Conwayridge (T), Ginserly (T), Imnaha, Needhill, Roundbarn, Saturday, Skullhollow (T), and Wilt series. Conwayridge soils have 10 to 18 percent clay in the control section and the thickness of the argillic horizon is 7 to 9 inches thick. Ginserly, Needhill, and Saturday soils are deep to lithic contacts. Imnaha, Skullhollow, and Wilt soils are moderately deep to lithic contacts. Roundbarn soils are deep to a paralithic contact.
GEOGRAPHIC SETTING: Loganvalley soils are on long, narrow, convex, fan remnants of glacio fluvial deposits in mountain valleys. Slopes are 1 to 20 percent. Elevations range from 5,000 to 5,800 feet. The climate is characterized by cold, wet winters and hot, dry summers. The mean annual precipitation is 20 to 30 inches, mean annual temperature is 41 to 45 degrees F., and the frost-free period is 30 to 80 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Frenchcabin, Magill, Stanbro, Starglade, and Weberg soils. Frenchcabin soils are fine-silty over sandy or sandy-skeletal, somewhat poorly drained, and are on stream terraces within mountain meadows. Magill and Starglade soils are well drained, loamy-skeletal, and are on hills. Furthermore, Magill soils are moderately deep to igneous bedrock whereas Starglade soils are very shallow to the same bedrock. Stanbro soils are very poorly drained, very deep, have a histic epipedon, and are on fens. Weberg soils are loamy-skeletal, moderately well drained, and are on glacial outwash plains.
DRAINAGE AND PERMEABILITY: Well drained; low or medium surface runoff; moderately slow permeability.
USE AND VEGETATION: Loganvalley soils are used for livestock grazing. The native vegetation is mainly mountain big sagebrush, low sagebrush, antelope bitterbrush, Idaho fescue; ecological sites are thick surface phase Shrubby Mountain Clayey 12-16PX R010XB028OR and thin suface phase Mountain Claypan 12-16PZ R010XB080OR.
DISTRIBUTION AND EXTENT: East central Oregon, MLRA 10. These soils are not extensive.
MLRA OFFICE RESPONSIBLE: Portland, Oregon
SERIES PROPOSED: Grant County Area, Oregon, 2003.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - The zone from the soil surface to 13 inches (A1, A2, and the 2Bt1 horizon).
Argillic horizon - The zone from 8 to 23 inches (Bt1 and Bt2 horizons).
Vitrandic intergrade properties - The zone from the soil surface to 8 inches (A1 and A2 horizons).
Particle-size control section - The zone from 8 to 23 inches (2Bt1 and 2Bt2 horizons).