Detailed Soil Map Units
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63—Umak paragravelly ashy fine sandy loam, dry, 0 to 10 percent slopes
Map Unit Setting
General location: Pumice flows in valleys in the southeastern part of the park
Major land resource area (MLRA): 3
Elevation: 5,000 to 5,500 feet
Average annual precipitation: 40 to 60 inches
Average annual air temperature: 38 to 42 degrees F
Frost-free period: 0 to 50 days
Map Unit Composition
Umak and similar soils:
85 percent
Minor components: 15 percent
Characteristics of the Umak and Similar Soils
Setting
Landform: Ashflow
Geomorphic position: Valleys
Parent material: Pumice and ash
Properties and qualities
Slope: 0 to 10 percent
Percentage of surface covered with stones and boulders: None
Restrictive features: None within a depth of 60 inches
Drainage class: Excessively drained
Permeability: Very rapid
Flooding: Not present
Water table: Not present
Ponding: Not present
Available water capacity: About 7.8 inches
Interpretive groups
Ecological site: Forestland—(003XY708OR) Abies-Pinus monticola/Arctostaphylos nevadensis
Typical profile
Oi—0 to 1 inch; slightly decomposed plant material
A—1 inch to 5 inches; paragravelly ashy fine sandy loam
Bw1—5 to 21 inches; very paracobbly ashy coarse sandy loam
Bw2—21 to 43 inches; extremely paracobbly ashy loamy coarse sand
Bw3—43 to 62 inches; extremely paracobbly ashy loamy coarse sand
Characteristics of the Minor Components
Timbercrater soils
Percentage of map unit: 10 percent
Landform: Ashflow
Geomorphic position: Ashfall and ashflow deposits with gravel-sized pumice in valleys
Castlecrest soils
Percentage of map unit: 5 percent
Landform: Ashflow
Geomorphic position: Ash deposits in valleys
Major Soil Features and Properties Affecting Management
Umak soil
• High pumice content
• Paracobbles on surface and in profile
• Very rapid permeability
