LOCATION CHOCHOCO ORTentative Series
TAXONOMIC CLASS: Ashy over loamy-skeletal, glassy over isotic Humic Xeric Vitricryands
TYPICAL PEDON: Chochoco ashy sandy loam, rangeland at an elevation of 2048 meters (6720 feet) on a 2 percent south slope. (Colors are for moist soil unless otherwise noted.)
A1--0 to 8 centimeters (0 to 3 inches); dark brown (10YR 3/3) gravely ashy sandy loam, brown (10YR 4/3) dry; single grain; loose, slightly sticky and slightly plastic; many very fine roots; many very fine interstitial pores; 30 percent gravel; moderately acid (pH 6.0); clear wavy boundary. (5 to 10 centimeters thick)
A2--8 to 25 centimeters (3 to 10 inches); dark brown (10YR 3/3) ashy sandy loam, brown (10YR 4/3) dry; weak very fine and fine granular structure; soft, very friable, slightly sticky and slightly plastic; many very fine, common fine and medium roots; many very fine interstitial pores; 10 percent gravel; moderately acid (pH 6.0); clear wavy boundary. (15 to 25 centimeters thick)
AB--25 to 54 centimeters (10 to 21 inches); dark brown (10YR 3/3) ashy loam, brown (10YR 4/3) dry; moderate medium subangular blocky structure; slightly hard, friable, moderately sticky and moderately plastic; many very fine, common fine, few medium, and common course roots; many very fine interstitial, and common dendritic tubular pores; 10 percent gravel; moderately acid (pH 6.0); clear wavy boundary. (15 to 35 centimeters thick)
2Bw--54 to 71 centimeters (21 to 28 inches); dark yellowish brown (10YR 3/4) extremely cobbly ashy loam, brown (10YR 5/3) dry; moderate medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; common very fine, few fine, medium, and course roots; many very fine interstitial, and common dendritic tubular pores; 25 percent gravel, 40 percent cobbles; moderately acid (pH 6.0); clear wavy boundary. (10 to 25 centimeters thick)
2Bt--71 to 86 centimeters (28 to 34 inches); dark yellowish brown (10YR 3/4) extremely cobbly loam, pale brown (10YR 6/3) dry; moderate medium subangular blocky structure; moderately hard, firm, moderately sticky and moderately plastic; few very fine roots throughout; common very fine dendritic tubular pores; few faint clay films on faces of peds; 10 percent gravel and 70 percent cobbles; moderately acid (pH 6.0); abrupt irregular boundary. (0 to 20 centimeters thick)
2R--86 centimeters (34 inches); basalt.
TYPE LOCATION: Wheeler, Oregon; Ochoco National Forest; 1550 feet east of Mount Pisgah Fire Lookout; 1600 feet north and 1300 feet west of the south east corner of section 8, T.13 S., R.21 E.
Datum: NAD 83
Latitude: 44 degrees, 27 minutes, 23.2 seconds North
Longitude: 120 degrees, 13 minutes, 48.8 seconds South
UTM Coordinates: Zone: 10, Northing: 4926303, Easting: 720358
RANGE IN CHARACTERISTICS: Chochoco soils are usually moist and are dry for 45 to 60 consecutive days. The mean annual soil temperature is 4 to 6 degrees C (40 to 43 degrees F). The mean summer soil temperature without an O horizon is 12 to 15 degrees C (54 to 59 degrees F).
Depth to bedrock is 50 to 100 centimeters. (20 to 40 inches).
Thickness of andic soil properties, the mollic epipedon and depth to contrasting loamy-skeletal material is 35 to 60 centimeters. (14 to 24 inches).
The A and AB horizons has chroma of 2 or 3 moist and dry. It has 10 to 30 percent gravel. It has 30 to 50 percent glass, 25 to 50 percent phosphate retention, acid oxalate aluminum plus one-half the iron is 0.4 to 1.0 and 15bar water dry is 10 to 12 percent.
The 2Bw horizon has chroma of 2 or 3 moist and 3 or 4 dry. It is ashy loam or ashy clay loam with 15 to 30 percent clay. It is 35 to 70 percent total rock fragments with 10 to 50 percent gravel and 20 to 60 percent cobbles. It has 5 to 30 percent glass, 10 to 30 percent phosphate retention, acid oxalate aluminum plus one-half the iron is 0.2 to 0.6.
The 2Bt horizon has chroma of 3 or 4 moist and 3 or 4 dry. It is loam and clay loam with 15 to 30 percent clay. It has 50 to 90 percent total rock fragments with 10 to 50 percent gravel and 40 to 70 percent cobbles.
COMPETING SERIES: These are the Leonardo, and Toroda series. These soils are greater than 150 centimeters deep.
GEOGRAPHIC SETTING: Chochoco soils formed in volcanic ash over colluvium and residuum from basalt. Slopes are 0 to 30 percent. The climate is characterized by cool moist winters and cool dry summers. Elevation is 1950 to 2073 meters (6400 to 6800 feet). The mean annual precipitation is 610 to 914 millimeters (24 to 36 inches). The mean annual air temperature is 1.7 to 3.3 degrees C (33 to 38 degrees F). The frost-free period is 25 to 70 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Mountemily and the Troutmeadows soils. Mountemily and Troutmeadows soils are forested and have a udic soil moisture regime.
DRAINAGE AND PERMEABILITY: Well drained; moderately rapid over moderate permeability.
USE AND VEGETATION: These soils are used for wildlife habitat. Vegetation consists of mountain big sagebrush, mountain snowberry, Feather Solomonplume.
DISTRIBUTION AND EXTENT: Central Oregon; MLRA 10 and 43C. This series is not extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES PROPOSED: Wheeler, Oregon, 2007. Chochoco was a Shoshone chief in the Prineville area in the 1800s.
REMARKS: Diagnostic horizons and features recognized in this pedon:
Mollic epipedon - 0 to 54 centimeters (A1, A2, AB horizons)
Andic properties - 0 to 54 centimeters (A1, A2, AB horizons)
Particle-size control section - 0 to 86 centimeters (A1, A2, AB, 2Bw, 2Bt horizons); 0 to 54 cm is ashy and 54 to 86 cm is loamy-skeletal.