57—Timbercrater-Llaorock complex, 10 to 30 percent north slopes
Map Unit Setting
General location: Side slopes of mountains and buttes
Major land resource area (MLRA): 3
Elevation: 5,500 to 6,500 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
Timbercrater and similar soils: 55 percent
Llaorock and similar soils: 40 percent
Minor components: 5 percent
Characteristics of the Timbercrater and Similar Soils
Setting
Landform: Ashfall
Geomorphic position: Side slopes of mountains and buttes
Parent material: Ash and pumice
Properties and qualities
Slope: 10 to 30 percent; northwest to northeast aspects
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 8.1 inches
Interpretive groups
Ecological site: Forestland—(003XY706OR) Tsuga mertensiana/Luzula glabrata var. hitchcockii
Typical profile
Oi—0 to 2 inches; slightly decomposed plant material
A—2 to 5 inches; paragravelly ashy loamy sand
Bw—5 to 16 inches; very paragravelly ashy loamy sand
C1—16 to 20 inches; extremely paragravelly ashy sand
C2—20 to 62 inches; extremely paragravelly ashy sand
Characteristics of the Llaorock and Similar Soils
Setting
Landform: Stratovolcano
Geomorphic position: Side slopes of mountains and buttes
Parent material: Ash mixed with residuum and colluvium derived from andesite
Properties and qualities
Slope: 10 to 30 percent; northwest to northeast aspects
Percentage of surface covered with stones and boulders: 3 percent
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 9 inches
Interpretive groups
Ecological site: Forestland—(003XY706OR) Tsuga mertensiana/Luzula glabrata var. hitchcockii
Typical profile
Oi—0 to 1 inch; slightly decomposed plant material
A—1 inch to 7 inches; gravelly ashy sandy loam
AB—7 to 14 inches; very stony ashy sandy loam
Bw1—14 to 24 inches; extremely stony medial sandy loam
Bw2—24 to 61 inches; extremely stony medial sandy loam
Characteristics of the Minor Components
Rock outcrop
Percentage of map unit: 5 percent
Landform: Stratovolcano
Geomorphic position: Andesitic lava flows on side slopes of mountains and buttes
Major Soil Features and Properties Affecting Management
Timbercrater soil
• High pumice content
• Very rapid permeability
Llaorock soil
• Rock fragments on surface
• Rock fragments in soil profile
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