Detailed Soil Map Units
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51—Sunnotch-Unionpeak complex, 15 to 35 percent slopes
Map Unit Setting
General location: Ash and cinder flows on side slopes of Mount Mazama
Major land resource area (MLRA): 3
Elevation: 5,000 to 7,000 feet
Average annual precipitation: 50 to 70 inches
Average annual air temperature: 38 to 42 degrees F
Frost-free period: 0 to 50 days
Map Unit Composition
Sunnotch and similar soils:
50 percent
Unionpeak and similar soils: 40 percent
Minor components: 10 percent
Characteristics of the Sunnotch and Similar Soils
Setting
Landform: Debris flow
Geomorphic position: Side slopes of Mount Mazama
Parent material: Cinders and ash
Properties and qualities
Slope: 15 to 35 percent
Percentage of surface covered with stones and boulders: None
Restrictive features: None within a depth of 60 inches
Drainage class: Somewhat excessively drained
Permeability: Rapid
Flooding: Not present
Water table: Not present
Ponding: Not present
Available water capacity: About 6.6 inches
Interpretive groups
Ecological site: Forestland—(003XY706OR) Tsuga mertensiana/Luzula glabrata var. hitchcockii
Typical profile
Oi—0 to 1 inch; slightly decomposed plant material
A1—1 inch to 3 inches; gravelly ashy sandy loam
A2—3 to 11 inches; ashy loamy sand
Bw—11 to 25 inches; very gravelly ashy loamy sand
2C—25 to 61 inches; very gravelly ashy sand
Characteristics of the Unionpeak and Similar Soils
Setting
Landform: Ashflow
Geomorphic position: Ashflow material on side slopes of Mount Mazama
Parent material: Pumice, ash, and dacite and andesite fragments
Properties and qualities
Slope: 15 to 35 percent
Percentage of surface covered with stones and boulders: None
Restrictive feature: Duripan at a depth of 20 to 40 inches
Drainage class: Somewhat excessively drained
Permeability: Moderately rapid or rapid
Flooding: Not present
Water table: Not present
Ponding: Not present
Available water capacity: About 4.3 inches
Interpretive groups
Ecological site: Forestland—(003XY706OR) Tsuga mertensiana/Luzula glabrata var. hitchcockii
Typical profile
Oi—0 to 1 inch; slightly decomposed plant material
A1—1 inch to 4 inches; ashy sandy loam
A2—4 to 8 inches; ashy loamy sand
Bw—8 to 30 inches; gravelly ashy loamy sand
Bqm—30 to 45 inches; cemented ashy loamy sand
C—45 to 65 inches; gravelly ashy loamy sand
Characteristics of the Minor Components
Castlecrest soils
Percentage of map unit: 5 percent
Landform: Ashflow
Geomorphic position: Ashflow material on side slopes of Mount Mazama
Timbercrater soils
Percentage of map unit: 5 percent
Landform: Ashflow
Geomorphic position: Ashfall and ashflow material on side slopes of Mount Mazama
Major Soil Features and Properties Affecting Management
Sunnotch soil
• Rock fragments in soil profile
• Sandy textures
Unionpeak soil
• Depth to hardpan
• Dustiness if vegetation is removed
• Low water-holding capacity
