128 Classification of the Soils – Umak Series

Classification of the Soils
 Umak Series

Depth class: Very deep

Drainage class: Excessively drained

Permeability: Very rapid

Position on landscape: Pumice flows

Parent material: Pumice and ash

Slope range: 0 to 10 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-pumiceous, amorphic Typic Vitricryands

 Typical Pedon

 Oi—0 to 1 inch; slightly decomposed organic material; 20 percent pumice paragravel and 10 percent pumice paracobbles; abrupt wavy boundary.

A—1 inch to 5 inches; very dark grayish brown (10YR 3/2) paragravelly ashy fine sandy loam, brown (10YR 5/3) dry; weak fine granular structure; soft, very friable, nonsticky and nonplastic; common very fine and fine roots and few medium roots; many very fine interstitial pores; 20 percent pumice paragravel and 5 percent pumice paracobbles; moderately acid (pH 6.0); clear wavy boundary.

Bw1—5 to 21 inches; brown (10YR 4/3) very paracobbly ashy coarse sandy loam, very pale brown (10YR 7/4) dry; weak fine subangular blocky structure; soft, very friable, nonsticky and nonplastic; common very fine and fine roots and few medium roots; common very fine interstitial pores; 20 percent pumice paragravel and 30 percent pumice paracobbles; slightly acid (pH 6.2); clear wavy boundary.

Bw2—21 to 43 inches; brown (7.5YR 4/4) extremely paracobbly ashy loamy sand, light brown (7.5YR 6/4) dry; weak fine subangular blocky structure; slightly hard, very friable, nonsticky and nonplastic; few fine and medium roots; few very fine interstitial pores; 30 percent pumice paragravel, 30 percent pumice paracobbles, and 10 percent pumice parastones; slightly acid (pH 6.4); clear wavy boundary.

Bw3—43 to 62 inches; brown (7.5YR 4/4) extremely paracobbly ashy loamy sand, pinkish gray (7.5YR 6/2) dry; weak medium subangular blocky structure; soft, very friable, nonsticky and nonplastic; 40 percent pumice paragravel, 20 percent pumice paracobbles, 10 percent cinder cobbles, and 10 percent pumice parastones; neutral (pH 6.6).

 Typical Pedon Location

 Map unit in which located: Umak paragravelly ashy fine sandy loam, 0 to 7 percent slopes

Location in park: About 2.5 miles east of the western boundary of Crater Lake National Park, on State Highway 62 and about 100 feet north of the road; 562044 meters easting and 4748433 meters northing, UTM Zone 10T, NAD 27; lat. 42o53’15.94″ N., long. 122o14’28.85″ W.

 Range in Characteristics

 Profile:

Depth to bedrock—more than 60 inches

Average content of pumice (more than 2-millimeter fraction)—more than 35 percent

A horizon:

Value—2 or 3 moist, 4 or 5 dry

Chroma—2 or 3 moist or dry

Content of pumice paragravel—10 to 30 percent

Content of cinder gravel—0 to 10 percent

Content of andesite gravel—0 to 5 percent

Content of pumice paracobbles—0 to 10 percent Bw horizon:

Value—3 or 4 moist, 5 to 7 dry

Chroma—3 or 4 moist or dry

Texture—ashy loamy sand or ashy sandy loam

Content of pumice paragravel—10 to 45 percent

Content of cinder gravel—0 to 10 percent

Content of andesite gravel—0 to 5 percent

Content of pumice paracobbles—5 to 30 percent

Content of pumice parastones—0 to 10 percent

C horizon (where present):

Hue—7.5YR or 10YR

Value—3 or 4 moist, 4 or 5 dry

Chroma—2 to 4 moist or dry

Content of pumice paragravel—10 to 50 percent

Content of cinder gravel—0 to 15 percent

Content of andesite gravel—0 to 10 percent

Content of pumice paracobbles—15 to 50 percent

Content of pumice parastones—0 to 10 percent

 

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