LOCATION PEKA WAEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, mesic Vitrandic Haploxerolls
TYPICAL PEDON: Peka stony ashy sandy loam on a southeast facing 22 percent slope at 4,350 feet elevation in a grazed ponderosa pine, Douglas-fir, bluebunch wheatgrass forest. (Colors are for moist soil unless otherwise stated. All textures are apparent field textures.)
Oi--0 to 1 inch; slightly decomposed forest litter; abrupt smooth boundary. (1 to 3 inches thick)
A1--1 to 7 inches; very dark brown (10YR 2/2) stony ashy sandy loam, grayish brown (10YR 5/2) dry; weak fine granular structure; soft, very friable, nonsticky and nonplastic; common very fine, fine, medium and few coarse roots; common very fine and fine pores; 10 percent gravel, 5 percent cobbles, and 5 percent stones; neutral (pH 7.2); clear smooth boundary.
A2--7 to 16 inches; very dark grayish brown (10YR 3/2) gravelly ashy sandy loam, brown (10YR 5/3) dry; weak fine subangular blocky structure parting to weak fine granular; soft, very friable, nonsticky and nonplastic; common very fine, fine, medium and few coarse roots; common very fine and fine pores; 10 percent gravel and 5 percent cobbles; neutral (pH 7.2); clear smooth boundary. (combined thickness of the A horizon is 10 to 18 inches)
2Bw--16 to 25 inches; brown (10YR 4/3) very cobbly sandy loam, pale brown (10YR 6/3) dry; weak fine subangular blocky structure; soft, very friable, nonsticky and nonplastic; common very fine and fine and few medium and coarse roots; common very fine and fine pores; 25 percent gravel, 20 percent cobbles, and 5 percent stones; neutral (pH 7.0); clear wavy boundary. (9 to 19 inches thick)
2C--25 to 50 inches; brown (10YR 5/3) very cobbly sandy loam, pale brown (10YR 6/3) dry; massive; soft, very friable, nonsticky and nonplastic; common very fine and fine and few medium roots; few very fine and fine pores; 30 percent gravel, 20 percent cobbles, and 5 percent stones; slightly acid (pH 6.2); clear wavy boundary. (15 to 30 inches thick)
2Cd--50 to 61 inches; pale brown (10YR 6/3) very gravelly sandy loam, very pale brown (10YR 7/3) dry; massive; hard, firm, nonsticky and nonplastic; few very fine roots; few very fine and fine pores; 30 percent gravel and 10 percent cobbles; neutral (pH 7.0).
TYPE LOCATION: Okanogan County, Washington; Cayuse Mountain Quadrangle; about 1400 feet east and 200 feet north of the southeast corner of section 11, T. 37 N., R. 29 E. (Latitude 48 degrees, 42 minutes, 43 seconds North., Longitude 119 degrees, 08 minutes, 12 seconds West.)
RANGE IN CHARACTERISTICS: The mean annual soil temperature is 47 to 50 degrees F. These soils are usually moist but are dry between depths of 8 and 24 inches for 75 to 90 consecutive days following the summer solstice. The mollic epipedon is 10 to 18 inches thick. The particle-size control section is 3 to 8 percent clay and 35 to 60 percent granitic rock fragments. Base saturation (by sum) is 50 to 75 percent. Reaction is slightly acid to moderately alkaline throughout. Depth to densic horizon is 40 to 60 inches.
A horizon
Value: 2 or 3 moist, 4 or 5 dry.
Chroma: 2 or 3 dry or moist.
Fine-earth texture: ashy sandy loam.
It has an estimated moist bulk density of 1.10 to 1.30 g/cc, volcanic glass content of 5 to 20 percent, acid-oxalate extractable aluminum plus one-half of the acid-oxalate extractable iron of 0.4 to 1.0 percent, and 15-bar water retention of 5 to 10 percent for air dried samples.
Gravel: 10 to 25 percent gravel.
Cobbles: 0 to 10 percent cobbles.
Stones: 0 to 15 percent surface stones and boulders.
2Bw horizon
Value: 4 or 5 moist, 5 or 6 dry.
Chroma: 3 or 4 dry or moist.
Fine-earth texture: sandy loam.
Gravel: 20 to 40 percent gravel
Cobbles: 0 to 25 percent.
Stones: 0 to 10 percent.
2C horizon
Value: 4 or 5 moist, 6 or 7 dry.
Chroma: 2 to 4 dry or moist.
Fine-earth texture: sandy loam, coarse sandy loam, or loamy sand.
Gravel: 25 to 50 percent gravel.
Cobbles: 5 to 30 percent cobbles
Stones: 0 to 10 percent.
2Cd horizon
Moist bulk density - 1.70 to 2.00 g/cc
COMPETING SERIES: These are the Borgeau, Emily, Lenz, Louiecreek, Raiso, Speigle, Vanbrunt, and Whitestone series. All of these series lack a densic contact. Borgeau soils have a particle-size control section that averages 10 to 18 percent clay. Emily soils have a mollic epipedon that is 20 to 36 inches thick. Lenz, Raisio, and Vanbrunt soils are moderately deep to a lithic contact. Louiccreek soils have 8 to 15 percent clay in the particle-size control section and the base saturation (by sum) 75 to 100 percent except in the upper part of the A horizon. Speigle soils have 10 to 20 percent clay in the particle-size control section.
GEOGRAPHIC SETTING: Peka soils are on backslopes, footslopes, and toe-slopes of glaciated mountains. These soils formed in colluvium from glacial till with an influence of volcanic ash in the surface. Slopes are 15 to 65 percent and are mainly south or west-facing. Elevations range from 2,800 to 4,500 feet. The climate is characterized by warm, dry summers and cold, moist winters. The mean annual precipitation is 15 to 18 inches. The mean January temperature is about 25 degrees F.; mean July temperature is about 68 degrees F.; and the mean annual air temperature is about 47 degrees F. The frost-free period is 100 to 130 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Donavan, Swakane, and the competing Vanbrunt soils. Donavan soils are coarse-loamy. Swakane soils are 10 to 20 inches deep to a lithic contact.
DRAINAGE AND PERMEABILITY: Well drained, rapid runoff; moderately rapid permeability.
USE AND VEGETATION: Grazing, limited timber production, wildlife habitat, and watersheds are the principal uses. The native vegetation is ponderosa pine, Douglas-fir, arrowleaf balsamroot, bluebunch wheatgrass, Idaho fescue, and pinegrass.
DISTRIBUTION AND EXTENT: North-central Washington. The series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Okanogan County, Washington, 2005.
REMARKS: Diagnostic horizons and features recognized in this pedon:
Vitrandic soil properties: 1 to 16 inches.
Mollic epipedon: 1 to 16 inches.
Cambic horizon: 16 to 25 inches.
Particle-size control section: 11 to 41 inches.
Rock fragments: 35 to 60 percent rock fragments in the particle-size control section.