129 Classification of the Soils – Unionpeak Series

Classification of the Soils
 Unionpeak Series

 Depth class: Moderately deep to a duripan

Drainage class: Somewhat excessively drained

Permeability: Rapid throughout the solum and moderately rapid in the Bqm horizon

Position on landscape: Ashflows

Parent material: Pumice, ash, and andesite and dacite fragments

Slope range: 0 to 35 percent

Elevation: 4,500 to 7,000 feet

Average annual precipitation: 40 to 70 inches

Average annual air temperature: 38 to 42 degrees F

Frost-free period: 0 to 50 days

 Taxonomic class: Ashy, amorphic Typic Duricryands

 Typical Pedon

 Oi—0 to 1 inch; slightly decomposed needle litter; abrupt wavy boundary.

A1—1 inch to 4 inches; very dark grayish brown (10YR 3/2) ashy sandy loam, brown (10YR 5/3) dry; weak fine granular structure; soft, very friable, nonsticky and nonplastic; common very fine roots and few fine and medium roots; many very fine interstitial pores; 2 percent andesite gravel, 3 percent cinder gravel, and 5 percent pumice paragravel; moderately acid (pH 6.0); clear wavy boundary.

A2—4 to 8 inches; brown (10YR 4/3) ashy loamy sand, dark yellowish brown (10YR 4/4) dry; weak very fine subangular blocky structure; slightly hard, very friable, nonsticky and nonplastic; common very fine and fine roots and few medium roots; common very fine interstitial pores and common fine dendritic tubular pores; 2 percent andesite gravel, 3 percent cinder gravel, and 5 percent pumice paragravel; moderately acid (pH 6.0); clear wavy boundary.

Bw—8 to 30 inches; brown (10YR 4/3) gravelly ashy loamy sand, light brownish gray (10YR 6/2) dry; weak very fine subangular blocky structure; slightly hard, very friable, nonsticky and nonplastic; common very fine roots and few fine, medium, and coarse roots; common very fine interstitial pores; 15 percent andesite gravel, 10 percent cinder gravel, and 7 percent pumice paragravel; neutral (pH 6.6); gradual wavy boundary.

Bqm—30 to 45 inches; dark grayish brown (10YR 4/2) weakly cemented ashy loamy sand, light brownish gray (10YR 6/2) dry; massive parting to thick platy rocklike structure; hard, very friable, nonsticky and nonplastic; few very fine and fine roots; many very fine interstitial pores; common distinct relict redoximorphic concentrations on surface of plates; 5 percent andesite gravel and 5 percent cinder gravel; slightly acid (pH 6.4); clear wavy boundary.

C—45 to 65 inches; dark reddish brown (5YR 3/3) gravelly ashy loamy sand, reddish brown (5YR 5/3) dry; single grain; loose, nonsticky and nonplastic; many fine interstitial pores; 25 percent cinder gravel and 1 percent cinder cobbles; moderately acid (pH 6.4).

 Typical Pedon Location

 Map unit in which located: Unionpeak-Castlecrest-Sunnotch complex 0 to 15 percent slopes Location in park: About 1.5 miles southeast of Rim Drive junction, on the old east entrance road, and 700 feet north of road; 577216 meters easting and 4750353 meters northing, UTM Zone 10T, NAD 27; lat. 42o54’13.21″ N., long. 122o03’19.10″ W.

 Range in Characteristics

 Profile:

Depth to weakly cemented duripan—20 to 40 inches

Depth to bedrock—more than 60 inches

A horizon:

Value—2 or 3 moist, 3 to 5 dry

Chroma—2 or 3 moist or dry

Texture—ashy sandy loam or ashy loamy sand

Content of pumice paragravel—0 to 15 percent

Content of cinder gravel—0 to 10 percent

Content of andesite gravel—0 to 5 percent

Bw horizon:

Value—3 or 4 moist, 4 to 6 dry

Chroma—2 or 3 moist or dry

Texture—ashy loamy sand or ashy sandy loam

Content of pumice paragravel—0 to 10 percent

Content of cinder gravel—0 to 10 percent

Content of andesite gravel—0 to 5 percent

Bqm horizon:

Hue—5YR, 7.5YR, or 10YR

Value—3 or 4 moist, 4 or 5 dry

Chroma—2 or 3 moist or dry

Texture—ashy loamy sand or ashy sand

Dry consistence—hard in the upper part and slightly hard or soft in the lower part

Content of pumice paragravel—0 to 30 percent

Content of cinder gravel—0 to 25 percent

Content of andesite gravel—0 to 15 percent

Content of cinder cobbles—0 to 5 percent

Cementation—very weakly cemented or weakly cemented

C horizon:

Hue—5YR, 7.5YR, or 10YR

Value—3 or 4 moist, 4 or 5 dry

Chroma—2 or 3 moist or dry

Texture—ashy loamy sand or ashy sand

Content of pumice paragravel—0 to 30 percent

Content of cinder gravel—0 to 25 percent

Content of andesite gravel—0 to 15 percent

Content of cinder cobbles—0 to 5 percent

 

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