38—Llaorock-Rubble land-Rock outcrop complex, 60 to 90 percent north slopes
Map Unit Setting
General location: Steep side slopes, mainly of the caldera rim
Major land resource area (MLRA): 3
Elevation: 6,000 to 8,000 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
Llaorock and similar soils: 50 percent
Rubble land: 30 percent
Rock outcrop: 15 percent
Minor components: 5 percent
Characteristics of the Llaorock and Similar Soils
Setting
Landform: Stratovolcano
Geomorphic position: Steep side slopes of mountains, ridges, and the caldera rim
Parent material: Ash mixed with residuum and colluvium derived from andesite
Properties and qualities
Slope: 60 to 80 percent; northwest to northeast aspects
Percentage of surface covered with stones and boulders: 7 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 Rubble Land
Landform: Talus slope
Geomorphic position: Talus on side slopes of mountains, ridges, and the caldera rim
Parent material: Colluvium derived from andesite
Slope: 60 to 90 percent
Characteristics of the Rock Outcrop
Landform: Stratovolcano
Geomorphic position: Rock outcroppings on side slopes of mountains, ridges, and the caldera rim
Parent material: Andesite
Slope: 60 to 90 percent
Characteristics of the Minor Components
Timbercrater soils
Percentage of map unit: 5 percent
Landform: Ashfall
Geomorphic position: Pumice and ashfall deposits on side slopes of mountains, ridges, and the caldera rim
Major Features and Properties Affecting Management
Llaorock soil
• Rock fragments on surface
• Steep and unstable slopes
• Rock fragments in soil profile
• Water erosion
Rubble land
• Steep and unstable slopes
• Rock fragments
• Lack of soil material
Rock outcrop
• Lack of soil material
