Classification of the Soils

Dyarock Series

 Depth class: Very deep

Drainage class: Moderately well drained

Permeability: Rapid

Position on landscape: Swales and drainageways on mountains

Parent material: Ash, pumice, cinders, and andesite fragments

Slope range: 2 to 20 percent

Elevation: 6,000 to 7,500 feet

Average annual precipitation: 60 to 80 inches

Average annual air temperature: 38 to 42 degrees F

Frost-free period: 0 to 30 days

 Taxonomic class: Ashy, amorphic Oxyaquic Vitricryands

 Typical Pedon

 A1—0 to 1 inch; very dark brown (10YR 2/2) very gravelly ashy loamy sand, grayish brown (10YR 5/2) dry; single grain; loose, nonsticky and nonplastic; few very fine and fine roots; many very fine interstitial pores; 25 percent andesite gravel, 5 percent andesite cobbles, 5 percent andesite stones, and 15 percent pumice paragravel; moderately acid (pH 6.0); clear wavy boundary.

A2—1 inch to 7 inches; very dark brown (10YR 2/2) ashy sandy loam, brown (10YR 5/3) dry; weak very fine granular structure; soft, very friable, nonsticky and nonplastic; many very fine and fine roots; many very fine and common fine interstitial pores; 5 percent andesite gravel and 5 percent andesite cobbles; slightly acid (pH 6.2); clear wavy boundary.

AB—7 to 17 inches; very dark brown (10YR 2/2) ashy sandy loam, brown (10YR 5/3) dry; weak very fine subangular blocky structure; soft, very friable, nonsticky and nonplastic; common very fine and fine roots; many very fine and common fine interstitial pores; 2 percent andesite gravel; slightly acid (pH 6.2); clear wavy boundary.

Bw—17 to 30 inches; very dark grayish brown (10YR 3/2) ashy loamy sand, grayish brown (10YR 5/2) dry; weak fine subangular blocky structure; soft, very friable, nonsticky and nonplastic; many very fine and fine interstitial pores; 2 percent andesite gravel; slightly acid (pH 6.2); clear wavy boundary.

C1—30 to 44 inches; dark brown (7.5YR 3/3) gravelly ashy loamy coarse sand, brown (7.5YR 5/2) dry; massive; slightly hard, very friable, nonsticky and nonplastic; many very fine and common fine interstitial pores; 15 percent andesite gravel; slightly acid (pH 6.2); clear wavy boundary.

C2—44 to 62 inches; dark grayish brown (10YR 4/2) ashy coarse sand, light brownish gray (10YR 6/2) dry; single grain; loose, nonsticky and nonplastic; many fine and medium interstitial pores; 3 percent andesite gravel and 7 percent pumice paragravel; slightly acid (pH 6.2).

 Typical Pedon Location

 Map unit in which located: Cleetwood-Sunnotch-Castlecrest complex, high elevation, 15 to 30 percent slopes

Location in park: About 1 mile north of Watchman Lookout and just west of the caldera rim; 567758 meters easting and 4755351 meters northing, UTM Zone 10T, NAD 27

 Range in Characteristics

 Profile:

Depth to bedrock—more than 60 inches

Thickness of solum—14 to 30 inches

Content of pumice—0 to 15 percent

Content of clay—0 to 5 percent

Depth to perched water table (from spring runoff)—within 36 inches of the surface for 20 consecutive days or more

A1 horizon:

Value—2 or 3 moist, 3 to 5 dry

Chroma—2 or 3 moist or dry

Texture—very gravelly ashy loamy sand or very gravelly ashy sandy loam

Content of rock fragments—35 to 55 percent

Content of organic matter—1 to 2 percent

A2 horizon:

Value—2 or 3 moist, 4 or 5 dry

Chroma—2 or 3 moist or dry

Texture—ashy sandy loam or ashy loamy sand

Content of rock fragments—0 to 30 percent

Content of organic matter—less than 1 percent

AB and Bw horizons:

Hue—10YR or 7.5YR

Value—2 to 4 moist, 3 to 5 dry

Chroma—2 to 4 moist or dry

Texture—ashy loamy sand or ashy sandy loam

Content of rock fragments—0 to 25 percent

Content of organic matter—less than 1 percent

C horizon:

Hue—10YR, 7.5YR, or 5YR

Value—3 or 4 moist, 4 to 6 dry

Chroma—2 to 4 moist or dry

Texture—ashy loamy sand, ashy coarse sand, or ashy loamy coarse sand

Content of rock fragments—0 to 25 percent

 

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