LOCATION CIRCLE OREstablished Series
TAXONOMIC CLASS: Ashy, glassy, frigid Alfic Vitrixerands
TYPICAL PEDON: Circle ashy sandy loam - woodland, on a 4 percent convex south-facing slope at 3000 feet elevation. (When described (8-7-84), soil was moist below 3 inches. Colors are for moist soil unless otherwise noted.)
Oi--0 to 1 inch; slightly decomposed litter of ponderosa pine needles and antelope bitterbrush leaves and twigs.
A1--1 to 4 inches; dark brown (10YR 3/3) ashy sandy loam, dark yellowish brown (10YR 4/4) dry; moderate fine granular structure; slightly hard, friable, nonsticky and nonplastic; many very fine and few fine roots; many very fine interstitial pores; 2 percent rounded gravel; neutral (pH 7.2); gradual wavy boundary.
A2--4 to 17 inches; dark brown (10YR 3/3) ashy sandy loam, dark yellowish brown (10YR 4/4) dry; weak fine granular structure; slightly hard, friable, nonsticky and nonplastic; common very fine and few fine, medium, and coarse roots; many very fine interstitial pores; 2 percent rounded gravel; neutral (pH 7.2); gradual wavy boundary. (Combined thickness of the A horizon is 14 to 18 inches)
2Bwb1--17 to 29 inches; dark brown (7.5YR 3/4) ashy loam, dark yellowish brown (10YR 4/4) dry; weak fine and medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; few very fine, fine medium, and coarse roots; common very fine interstitial and vesicular and few fine tubular pores; 5 percent rounded gravel; neutral (pH 7.0); clear irregular boundary.
2Bwb2--29 to 43 inches; dark yellowish brown (10YR 3/4) gravelly ashy loam, brown (10YR 4/3) dry; moderate medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; few fine, medium and coarse roots; common fine vesicular and common medium tubular pores; 25 percent rounded gravel; neutral (pH 7.0); gradual wavy boundary. (Combined thickness of the 2Bwb is 20 to 35 inches)
3Btb3--43 to 66 inches; dark yellowish brown (10YR 3/4) very gravelly medial clay loam, brown (10YR 4/3) dry; moderate medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; few fine medium and coarse roots; common fine vesicular and common medium tubular pores; few faint clay films on peds; 40 percent rounded gravel; 10 percent rounded cobbles, 8-13 centimeters; neutral (pH 7.0).
TYPE LOCATION: Jefferson County, Oregon; 1.2 miles on USFS road 200 from road 1230; northwest quarter of the southeast quarter of sec. 29, T. 12 S., R. 9 E. (Latitude 44 degrees, 30 minutes, 1 second N, Longitude 121 degrees, 41 minutes, 00 seconds W)
RANGE IN CHARACTERISTICS: The depth to the buried glacial outwash material (3Btb) is 40 to 50 inches. Depth to bedrock s greater than 60 inches. The soil is usually moist, but is dry in all parts for 60 to 90 consecutive days after the summer solstice. The mean annual soil temperature is 42 to 47 degrees F. The mean summer soil temperature is 47 to 54 degrees F. The umbric epipedon is 14 to 18 inches thick. The ash mantle (A and 2B horizons 1 to 43 inches) contains 50 to 70 percent glass and glass-coated aggregate, phosphate retention of 75 to 85 percent, acid oxalate aluminum plus one-half the acid oxalate iron is 1.5 to 2.5 percent, and the 15-bar water content on dried and undried samples is 8 to 12 percent. The soil is slightly acid or neutral.
The Oi horizon is 1 to 3 inches thick except where disturbed.
The A horizon has hue of 10YR moist and dry with value of 2 or 3 moist and 4 or 5 dry and chroma of 2 or 3 moist and 2 to 4 dry. It is 5 to 15 percent estimated clay. It has 0 to 10 percent rounded gravel. Base saturation is 40 to 50 percent by ammonium acetate.
The 2Bwb horizon has 15 to 27 percent estimated clay. It has 0 to 25 percent rounded gravel. It is loam and gravelly loam.
The 3Btb horizon has 27 to 35 percent estimated clay. It has 30 to 50 percent rounded gravel and 5 to 15 percent rounded cobbles. Total rock fragments range from 35 to 60 percent. It contains 30 to 60 percent glass and glass-coated aggregate, phosphate retention of 65 to 85 percent, acid oxalate aluminum plus one-half the acid oxalate iron of 2.0 to 3.0 percent, and the 15-bar water content is 12 to 18 percent on dried samples and 20 to 30 percent on undried samples.
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING: The Circle soils are on glacial outwash plains at elevations of 2,500 to 3,500 feet. Slopes are 0 to 30 percent. The soils formed in ash deposits overlying glacial outwash. The climate is characterized by cold, wet winters and hot, dry summers. The mean annual precipitation is 20 to 40 inches. The mean annual temperature is 40 to 47 degrees F. The frost-free period is 50 to 90 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Allingham, Suilotem, Suttle, and Wizard soils. Allingham and Wizard soils are on glacial outwash plains and have very gravelly glacial outwash between 20 to 40 inches. Suttle soils are on glacial outwash plains have a cindery surface mantle and are ashy-skeletal. Suilotem soils are on glacial outwash plains and are somewhat poorly drained.
DRAINAGE AND PERMEABILITY: Well drained; permeability is moderate.
USE AND VEGETATION: These soils are used for timber production, wildlife habitat, recreation and watershed. Potential native vegetation is ponderosa pine, Douglas fir, grand fir, antelope bitterbrush, snowberry, greenleaf manzanita, and Idaho fescue.
DISTRIBUTION AND EXTENT: East slope of the Cascades in Central Oregon; MLRA 6. The series is not extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Jefferson County (Upper Deschutes River Area), Oregon, 1992.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
umbric epipedon - the zone from the mineral soil surface to a depth of 16 inches (A1, A2 horizons).
cambic horizon - the zone from 17 to 43 inches (2Bw horizon).
argillic horizon - from 43 to 66 inches (3Btb horizon)
Andic soil properties - based on laboratory data from the associated Allingham Series.
The soil material in the A and 2B horizons is weathered in Blue Lake and Sand Mountain tephra (3,440 years). The 3B horizon is weathered in "Jack Creek" glacial outwash (70,000 to 80,000 years).