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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