LOCATION MILLERFLAT OREstablished Series
TAXONOMIC CLASS: Loamy-skeletal, isotic, frigid Vitrandic Argixerolls
TYPICAL PEDON: Millerflat loam - on a 1 percent slope. (Colors are for moist soil unless otherwise noted.)
Oi--2 inches to 0; organic layer of needles and twigs.
A1--0 to 6 inches; very dark brown (7.5YR 2/2) loam, dark brown (7.5YR 4/2) dry; weak medium platy structure; soft, friable, nonsticky and nonplastic; many very fine, fine, and few medium and coarse roots; many very fine, fine, and few medium and coarse irregular pores; 10 percent gravel; moderately acid (pH 5.8); clear smooth boundary. (6 to 9 inches thick)
A2--6 to 14 inches; dark brown (7.5YR 3/3) loam, brown (7.5YR 5/3) dry; weak fine and medium subangular blocky structure; slightly hard, friable, nonsticky and nonplastic; many very fine, fine, and few medium and coarse roots; many very fine, fine, and few medium and coarse irregular pores; 5 percent gravel; moderately acid (pH 5.8); clear smooth boundary. (6 to 9 inches thick)
A3--14 to 22 inches; dark brown (7.5YR 3/3) loam, brown (7.5YR 5/3) dry; weak medium subangular blocky structure; slightly hard, friable, nonsticky and nonplastic; common very fine, fine, and few medium roots; common very fine, fine, and few medium tubular pores; 5 percent gravel; moderately acid (pH 5.6); clear smooth boundary. (8 to 12 inches thick)
Bw1--22 to 29 inches; dark brown (7.5YR 4/3) loam, light brown (7.5YR 6/3) dry; few fine distinct strong brown (7.5YR 4/6) mottles; moderate medium subangular blocky structure; hard, firm, nonsticky and nonplastic; common very fine, fine, and few medium roots; common very fine, fine, and few medium tubular pores; moderately acid (pH 5.6); clear smooth boundary. (5 to 8 inches thick)
Bw2--29 to 35 inches; brown (7.5YR 4/3) loam, light brown (7.5YR 6/3) dry; common fine distinct dark brown (7.5YR 3/2) and strong brown (7.5YR 4/6) mottles; moderate medium and coarse subangular blocky structure; hard, firm, nonsticky and nonplastic; few very fine and fine roots; few very fine and fine tubular pores; 5 percent gravel; moderately acid (pH 5.6); clear smooth boundary. (5 to 10 inches thick)
2Bt1--35 to 48 inches; brown (7.5YR 4/4) extremely gravelly sandy clay loam, light brown (7.5YR 6/3) dry; many fine distinct dark brown (7.5YR 3/2) and strong brown (7.5YR 4/6) mottles; weak medium subangular blocky structure; hard, firm, slightly sticky and slightly plastic; few very fine and fine tubular pores; few faint clay films on rock fragments and on ped faces; 55 percent gravel and 10 percent cobbles; moderately acid (pH 5.6); clear wavy boundary. (12 to 15 inches thick)
2Bt2--48 to 60 inches; brown (7.5YR 4/4) extremely gravelly sandy clay loam, light brown (7.5YR 6/3) dry; many fine distinct dark brown (7.5YR 4/2) mottles; weak medium subangular blocky structure; very hard, very firm, sticky and plastic; few very fine and fine tubular pores; many distinct clay films on rock fragments and on ped faces; 60 percent gravel and 15 percent cobbles; moderately acid (pH 5.6).
TYPE LOCATION: Wasco County, Oregon: 1500 feet west and 2000 feet north of the SE corner of section 14, T.6 S., R.10 E. (Warm Springs Indian Reservation).
RANGE IN CHARACTERISTICS: These soils are usually moist but are dry in all parts of the moisture control section for 45 to 60 consecutive days within the four months that follow the summer solstice. The mean annual soil temperature is 43 to 45 degrees F. Depth to stratified gravelly and sandy alluvium is greater than 60 inches. The particle-size control section has 45 to 80 percent rock fragments and 25 to 35 percent field estimated clay. The mollic epipedon is 20 to 30 inches thick and may include the upper part of the Bw horizon. Depth to mottles with chroma of 2 (redox depletions) is 20 to 30 inches. Depth to the 2Bt horizon is 30 to 40 inches. Base saturation is assumed to be 50 to 70 percent within some part of the upper 30 inches of the solum. The upper part of the solum is estimated to have a phosphate-retention of 25 to 35 percent, acid oxalate extractable aluminum plus one-half iron of 0.4 to 1.0 percent, and volcanic glass and glass coated aggregate of 5 to 20 percent.
The A horizon has value of 2 or 3 moist, 4 or 5 dry, and chroma of 2 or 3 moist and dry. It has 0 to 10 percent gravel.
The Bw horizon has value of 3 or 4 moist, 5 or 6 dry, and chroma of 2 or 3 moist and dry. It is loam or silt loam with 15 to 20 percent clay. Rock fragments range from 0 to 10 percent gravel.
The 2Bt horizon has hue of 7.5YR or 10YR, value of of 4 or 5 moist, 5 or 6 dry, and chroma of 2 through 4 moist and dry. It is sandy clay loam or clay loam. Rock fragments range from 45 to 80 percent gravel and 5 to 20 percent cobbles.
COMPETING SERIES: These are the Roundbarn (T), Saturday (T), Stemilt, and Wilt series. Roundbarn soils are 40 to 60 inches to bedrock and are dry for 90 to 100 consecutive days. Saturday soils are 40 to 60 inches to bedrock and lack a cambic horizon above a 2Bt. Stemilt soils are 40 to 60 inches to bedrock and are dry for 60 to 75 consecutive days. Wilt soils are 20 to 40 inches to bedrock and are dry for 90 to 110 consecutive days.
GEOGRAPHIC SETTING: Millerflat soils are on nearly level slopes on stream terraces. Elevation ranges from 2600 to 3200 feet. Slopes are 0 to 3 percent. The soil formed in alluvium derived from mixed sources with an influence of volcanic ash. The climate is characterized by cold and wet winters and hot and dry summers. The mean annual precipitation is 30 to 40 inches. The mean annual temperature is 41 to 43 degrees F. The frost-free period is 60 to 90 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Kutcher, Mackatie, and Pipp soils. All of these soils are over andesite on adjacent uplands. Kutcher soils are ashy-skeletal, well drained, and are moderately deep to bedrock at higher elevations. Mackatie soils are ashy over loamy, well drained, and are deep to bedrock at higher elevations. Pipp soils are ashy-skeletal, somewhat excessively drained, deep to bedrock, and are on south-facing slopes.
DRAINAGE AND PERMEABILITY: Moderately well drained. Permeability is moderately slow. An apparent water table is at a depth of 1.5 to 2.5 feet from March to June.
USE AND VEGETATION: These soils are used for timber production, livestock grazing, watershed, and wildlife habitat. The native vegetation is ponderosa pine, Douglas fir, and western larch with an understory of common snowberry, golden chinkapin, starflower, and willow.
DISTRIBUTION AND EXTENT: North-central Oregon; MLRA 6. The soils of this series are not extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Wasco County (Warm Springs Indian Reservation), Oregon, 1993.
REMARKS: Diagnostic horizons and features in this pedon include:
Mollic epipedon - from the surface to 22 inches (A1, A2, and A3 horizons).
Mottles with chroma of 2 - from 29 inches (Bw2 horizon).
Argillic horizon - from 35 to 60 inches (2Bt1 and 2Bt2 horizons).
Vitrandic feature - from 0 to 35 inches (A1, A2, A3, Bw1, and Bw2 horizons)
Aquic feature - from 29 to 35 inches (Bw2 horizon) having chroma of 2 (redox depletions) and aquic conditions for some time in most years within upper 30 inches.
Particle-size control section - from 35 to 40 inches (upper 2Bt1 horizon).