LOCATION TOLO OR+WAEstablished Series
TAXONOMIC CLASS: Ashy over loamy, amorphic over isotic, frigid Alfic Vitrixerands
TYPICAL PEDON: Tolo ashy silt loam, forested, on a 10 percent northeast-facing slope at an elevation of 3,400 feet. (Colors are for moist soil unless otherwise noted.)
Oi--0 to 2 inches; mainly a loose layer of pine and fir needles; slightly decomposed needles 1/2 inch thick at the lower part.
A--2 to 3 inches; black (10YR 2/1) ashy silt loam, dark gray (10YR 4/1) dry; weak fine granular structure matted together with fine fibrous roots; soft, very friable, nonsticky and nonplastic; many very fine roots; many very fine interstitial pores; many white fungal mycelia; common small charcoal fragments; neutral (pH 6.6); abrupt smooth boundary. (1 to 3 inches thick)
Bw1--3 to 6 inches; brown (10YR 4/3) ashy silt loam, light brownish gray (10YR 6/2) dry; massive; soft, very friable, nonsticky and nonplastic; many fine roots; common very fine pores; common small charcoal fragments; slightly acid (pH 6.2); abrupt smooth boundary.
Bw2--6 to 20 inches; brown (10YR 4/3) ashy silt loam, pale brown (10YR 6/3) dry; massive; soft, very friable, nonsticky and nonplastic; many fine roots; common very fine pores; few small charcoal fragments; slightly acid (pH 6.2); gradual smooth boundary.
Bw3--20 to 35 inches; brown (10YR 4/3) ashy silt loam, pale brown (10YR 6/3) dry; massive; slightly hard, very friable, nonsticky and nonplastic; common roots; many very fine pores; 2 to 3 mm thick band having clay films at the lower boundary; moderately acid (pH 6.0); abrupt wavy boundary. (Combined thickness of the Bw horizon is 12 to 36 inches)
2Btb1--35 to 39 inches; dark yellowish brown (10YR 4/4) silt loam, brown (10YR 5/3) dry; weak medium and coarse prismatic and moderate medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; common roots; many very fine tubular pores; few faint clay films on peds and in pores; common white mycelia fungus on faces of peds; moderately acid (pH 6.0); clear wavy boundary. (0 to 11 inches thick)
2Btb2--39 to 43 inches; dark yellowish brown (10YR 4/4) silty clay loam, brown (10YR 5/3) dry; weak medium and coarse prismatic and moderate medium and fine subangular blocky structure; hard, firm, moderately sticky and moderately plastic; common roots; many very fine tubular pores; continuous faint clay films; common white mycelial fungus on faces of peds; slightly acid (pH 6.2); gradual smooth boundary. (2 to 6 inches thick)
2Btb3--43 to 52 inches; dark yellowish brown (10YR 4/4) silty clay loam, pale brown (10YR 6/3) dry; weak medium and coarse prismatic and moderate fine subangular blocky structure; hard, firm, moderately sticky and moderately plastic; common roots; many very fine and common fine tubular pores; continuous faint clay films on peds and in pores; slightly acid (pH 6.2); gradual smooth boundary. (4 to 18 inches thick)
2Btb4--52 to 67 inches; brown (10YR 4/3) silt loam, brown (10YR 5/3) dry; weak fine subangular blocky structure; hard, firm, slightly sticky and slightly plastic; few roots; many very fine and common medium tubular pores; few faint clay films; slightly acid (pH 6.2).
TYPE LOCATION: Union County, Oregon; about 14 miles northeast of Elgin, Oregon, 450 feet east and 400 feet north of the SW corner of section 3, T. 2 N., R. 40 E.; 50 feet west of center of road; 950 feet south of road intersection on N-S section line; and 600 feet along road north of the east-west section line fence. (Latitude 45 degrees, 40 minutes, 36 seconds N, Longitude 117 degrees, 48 minutes, 19 seconds W)
RANGE IN CHARACTERISTICS: Tolo soils have a moist bulk density of 0.70 to 0.85 g/cubic centimeter, contain 60 to 70 percent glass in the ashy overlay, and have an estimated 5 to 15 percent clay . The mean annual soil temperature ranges from 43 to 47 degrees F. The soils are usually moist but are dry in all parts between depths of 8 and 24 inches for 45 to 75 consecutive days during the summer. Thickness of ashy materials and depth to contrasting materials range from 20 to 36 inches. Bedrock commonly is deeper than 60 inches to basalt bedrock but ranges to 40 inches in some areas. The soil reaction is moderately acid to neutral.
The A horizon has hue of 10YR or 7.5YR, value of 2 or 3 moist and 4 through 6 dry and chroma of 1 through 3 moist and dry.
The Bw horizon has hue of 10YR or 7.5YR, value of 3 to 5 moist, 5 to 7 dry and chroma of 2 through 4 moist and dry.
A 2Bwb horizon is present in some pedons, with color similar to the 2Btb horizon.
The 2Btb horizon has hue of 7.5YR or 10YR, value of 3 or 4 moist, 4 through 6 dry and chroma of 2 through 4 moist and dry. The upper part is silt loam, silty clay loam, or cobbly silty clay loam, averages 18 to 35 percent clay, and has 0 to 35 percent rock fragments; the lower part below 40 inches may range from sandy loam to silty clay loam and contains up to 50 percent subangular basalt cobbles and gravel.
COMPETING SERIES: These are the Dohert (T) and Torchsprings (T) series. The Brusher and Smiling series have a similar classification with glassy mineralogy.
Dohert soils - 20 to 40 inches deep to fractured lithic bedrock (argillite or metasedimentary); the ashy part of the pscs has 2 to 5 percent clay; the loamy part of the pscs has 5 to 20 percent subangular rock fragments of argillite or metasedimentary origin.
Torchsprings soils - the ashy part of the pscs has 5 to 8 percent clay; the loamy part of the pscs has 5 to 30 percent rounded and subrounded rock fragments of mixed glacial till origin.
Brusher soils - ashy part of pscs ranges to Ashy-L and Ashy-FSL with 30 to 60 percent glass and glassy mineralogy; loamy part of pscs has 0 to 25 percent subangular rock fragments of granitic or porphyritic origin; has 2E/B and 2B/E horizons below ash mantle.
Smiling soils - ashy part of pscs is Ashy-SL and glassy mineralogy; loamy part of pscs has 5 to 35 percent subangular rock fragments of basalt or andesite origin.
GEOGRAPHIC SETTING: The Tolo soils are on nearly level upland plateaus and steep north and east-facing mountain side slopes at elevations of 2,800 to 5,400 feet. Slopes are 2 to 65 percent. They formed in silty volcanic ash over older loamy mixed loess and colluvial materials of basalt origin. The climate is characterized by cold and wet winters and hot and dry summers. The mean annual temperature is 42 to 45 degrees F, the mean January temperature is 27 degrees F, and the mean July temperature is 61 degrees F. The mean annual precipitation ranges from 15 to 45 inches with about 80 percent falling between October and June. The frost-free period ranges from 30 to 110 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Anatone, Couse, Cowsly, Klicker, Olot, and Snell soils. All of these soils except Olot have less than 60 percent ash in any part of the profile. Anatone soils are less than 20 inches deep to bedrock. Couse and Cowsly soils have a mollic epipedon. Olot soils are 20 to 40 inches to bedrock and have a skeletal subsoil. Klicker and Snell soils have an argillic horizon and more than 35 percent rock fragments.
DRAINAGE AND PERMEABILITY: Well drained; moderately rapid permeability in the ashy surface layers and moderately slow permeability in the buried subsoil.
USE AND VEGETATION: These soils are used for timber production and live stock grazing with small areas at lower elevations cleared for cultivation. Principal trees include Douglas fir, grand fir, larch, ponderosa pine, and lodgepole pine.
DISTRIBUTION AND EXTENT: Northeastern Oregon, southeastern Washington and north-central Idaho; MLRA 43c. The series is extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Medford Area, Oregon, 1911.
REMARKS: Diagnostic horizons and features in this pedon include:
Ochric epipedon - from 2 to 2 inchs (A horizon)
Cambic horizon - from 3 to 36 inches (Bw1, Bw2, and Bw3 horizons)
Argillic horizon - from 36 to 67 inches (2Btb1, 2Btb2, and 2Btb3 horizons)
Andic soil properties - from mineral surface to 33 inches (A, Bw1, Bw2, and Bw3 horizons) having more than 60 percent volcanic glass and glass aggregate, more than 1.0 percent ammonium oxalate Al + 1/2Fe, and 5 to 12 percent 15-bar moisture content (air-dry).
Particle-size control section - 1 to 41 inches
This series has been reclassified 7/04 from ashy over loamy, mixed, frigid Typic Vitrandepts to ashy over loamy, amorphic over isotic, frigid Alfic Vitrixerands based on Keys to Taxonomy, 8th edition and supporting laboratory data from associated soils within the Blue Mountains.
[Vegetation spans dry day concepts: Grand fir/Douglas fir are typically in the 45 to 60 day zone; Douglas fir in the 60 to 75 dry day zone; and ponderosa pine in the 60 to 90 dry day zone. More investigation in the vegetation correlated to this series is needed.]
This series concept represents an example of the best undisturbed ash mantle in xeric moisture regime in Blue Mountains.
ADDITIONAL DATA: Characterization data on 2 profiles (S60-Oreg-31-1 and 60-Oreg-31-2) reported in Lincoln Soil Survey Laboratory Report for soils sampled in Union County, Oregon, 1960. Reference samples from NSSL for glass count 86T7089 and 86T7090.