LOCATION FAWNSPRING OREstablished Series
TAXONOMIC CLASS: Fine, smectitic, mesic Vitrandic Palexerolls
TYPICAL PEDON: Fawnspring very gravelly ashy silt loam - on a 15 percent northwest facing slope, forested. (Colors are for moist soil unless otherwise noted.)
Oi--0 to 2 inches; organic layer of needles and twigs.
A--2 to 5 inches; very dark gray (10YR 3/1) very gravelly ashy silt loam, dark grayish brown (10YR 4/2) dry; moderate fine subangular blocky parting to moderate fine granular structure; slightly hard, friable, nonsticky and nonplastic; many very fine, fine, and few medium and coarse roots; many very fine, fine, and few medium tubular pores; 40 percent gravel; neutral (pH 7.0); clear smooth boundary. (3 to 7 inches thick)
Bw--5 to 10 inches; very dark grayish brown (10YR 3/2) very gravelly ashy silty clay loam, dark gray (10YR 4/1) dry; moderate fine and medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; many very fine, fine, and few medium and coarse roots; many very fine, fine, and few medium and coarse tubular pores; many organic coatings on faces of peds and lining pores; 40 percent gravel; slightly acid (pH 6.4); abrupt smooth boundary. (5 to 8 inches thick)
2Bt1--10 to 18 inches; dark brown (7.5YR 3/3) clay, brown (7.5YR 4/2) dry, strong very coarse subangular blocky structure, very hard, very firm, very sticky and very plastic; common very fine, fine, medium, and few coarse roots; common very fine, fine, and few medium tubular pores; many prominent clay films on faces of peds and lining pores; 10 percent gravel; slightly acid (pH 6.2); clear smooth boundary. (6 to 14 inches thick)
2Bt2--18 to 28 inches; dark brown (7.5YR 3/3) clay, brown (7.5YR 4/2) dry; strong very coarse subangular blocky structure; extremely hard, extremely firm, very sticky and very plastic; few very fine, fine, and medium roots; few very fine and fine tubular pores; continuous prominent clay films on faces of peds and lining pores; 5 percent gravel; slightly acid (pH 6.2); clear smooth boundary. (6 to 10 inches thick)
3C1--28 to 36 inches; weak red (10R 4/3) clay, red (2.5YR 4/6) dry; massive; extremely hard, extremely firm, very sticky and very plastic; few very fine and fine roots; few very fine and fine tubular pores; slightly acid (pH 6.2); clear smooth boundary. (7 to 11 inches thick)
3C2--36 to 45 inches; weak red (10R 4/4) clay, red (2.5YR 4/6) dry; massive; hard, firm, sticky and plastic; few very fine and fine roots; few very fine and fine tubular pores; slightly acid (pH 6.2); clear smooth boundary. (8 to 12 inches thick)
3Cr--45 inches; sedimentary rock.
TYPE LOCATION: Wasco County, Oregon: 700 feet north and 400 feet east of the SW corner of section 19, T.7 S., R.13 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 60 to 90 consecutive days within the four months following the summer solstice. The mean annual soil temperature is 47 to 51 degrees F. Depth to bedrock is 40 to 60 inches. Depth to the 2Bt horizon is 8 to 15 inches. There is an absolute increase in clay of 15 to 30 percent between the Bw and the 2Bt horizons. The mollic epipedon is 20 to 35 inches thick and includes the upper part of the 2Bt horizon. The upper 7 to 14 inches of the solum is estimated to have 20 to 40 percent volcanic glass and 0.4 to 1.0 percent acid oxalate extractable aluminum plus one-half iron.
The A horizon has value of 2 or 3 moist, 4 or 5 dry, and chroma of 1 or 2 moist and dry. It has 10 to 20 percent clay and contains 25 to 40 percent gravel and 0 to 10 percent cobbles. Organic matter is 4 to 6 percent.
The Bw horizon has value of 2 or 3 moist, 4 or 5 dry, and chroma of 1 through 3 moist and dry. It is ashy silt loam or ashy silty clay loam and has 25 to 35 percent clay. It contains 25 to 40 percent gravel and 0 to 10 percent cobbles. Organic matter is 2 to 4 percent.
The 2Bt horizon has value of 3 or 4 moist, 4 or 5 dry, and chroma of 1 through 3 moist and dry. It is clay or silty clay and has 50 to 60 percent clay. It contains 0 to 10 percent gravel. Organic matter is 1 to 2 percent.
The 3C horizon has hue of 2.5YR or 10R, value of 4 or 5 moist, 4 through 6 dry, and chroma of 4 through 6 moist and dry. It is clay or silty clay and has 50 to 60 percent clay. It contains 0 to 10 percent gravel.
COMPETING SERIES: These are the Patron (T), Prill, and Ridley series. Patron soils are greater than 60 inches to bedrock and has 35 to 40 percent clay in the particle-size control section. Prill soils are 20 to 40 inches to bedrock. Ridley soils are greater than 60 inches to bedrock, are mildly alkaline in the 2Bt horizon, and have a 3Bk horizon.
GEOGRAPHIC SETTING: Fawnspring soils are on gently sloping to steep north-facing side slopes of mountains. Elevation ranges from 2200 to 3800 feet. Slopes are 2 to 30 percent. The soil formed in residuum and colluvium derived dominantly from sedimentary rock with an influence of volcanic ash. The climate is characterized by cool and wet winters and hot and dry summers. The mean annual precipitation is 16 to 20 inches, the mean annual temperature is 45 to 49 degrees F., and the frost-free period is 90 to 120 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Kaskela, Littlefawn, Mowako, Mutton, and Wakamo soils. Kaskela soils are very fine, montmorillonitic, and are on adjacent rangeland. Littlefawn soils are moderately deep to bedrock, and are on adjacent north-facing side slopes. Mowako soils are loamy-skeletal, moderately deep to bedrock, and are on south-facing side slopes. Mutton soils are ashy-skeletal and are on adjacent north-facing side slopes. Wakamo soils are clayey-skeletal, shallow to bedrock, and are on south-facing side slopes of mountains.
DRAINAGE AND PERMEABILITY: Well drained. Permeability is slow.
USE AND VEGETATION: These soils are used for timber production, livestock grazing, watershed and wildlife habitat. The native vegetation is ponderosa pine and Douglas fir with an understory of common snowberry, heartleaf arnica, Pacific serviceberry, Oregon white oak, and rose.
DISTRIBUTION AND EXTENT: Mutton Mountains of 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 - the zone from 2 to 28 inches (A, Bw, 2Bt1, 2Bt2).
Argillic horizon - the zone from 18 to 28 inches (2Bt1, 2Bt2).
Pale feature - argillic horizon with a clayey particle size class and abrupt upper boundary ( 2Bt2 horizon) with an increase of 15 percent absolute.
Vitrandic feature - from 2 to 10 inches (A and Bw horizon)
Ultic feature - base saturation is assumed to be 75 percent or less within the 2Bt horizon.
All depths to diagnostic horizons or other features are measured from the top of the first mineral horizon.